Article

An overview of the dental pulp: Its functions and responses to injury

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The dental pulp is a unique tissue and its importance in the long-term prognosis of the tooth is often ignored by clinicians. It is unique in that it resides in a rigid chamber which provides strong mechanical support and protection from the microbial rich oral environment. If this rigid shell loses its structural integrity, the pulp is under the threat of the adverse stimuli from the mouth, such as caries, cracks, fractures and open restoration margins, all of which provide pathways for micro-organisms and their toxins to enter the pulp. The pulp initially responds to irritation by becoming inflamed and, if left untreated, this will progress to pulp necrosis and infection. The inflammation will also spread to the surrounding alveolar bone and cause periapical pathosis. The magnitude of pulp-related problems should not be underestimated since their most serious consequence is oral sepsis, which can be life threatening, and hence correct diagnosis and management are essential. Clinicians must have a thorough understanding of the physiological and pathological features of the dental pulp as well as the biological consequences of treatment interventions.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Dental pulp ( Figure 1) is located in a rigid chamber which offers mechanical support and protection from the oral environment rich in microorganisms. Pulp structure is based on collagen molecules, proteoglycans, fibronectin and different types of glycoproteins [1]. In the peripheral zone of the pulp exists a layer of highly specialized cells, the odontoblasts [2]. ...
... In the peripheral zone of the pulp exists a layer of highly specialized cells, the odontoblasts [2]. Alongside these cells exist undifferentiated mesenchymal cells which will become odontoblast-like cells forming dentine if stimulated [1]. Other cellular components of dental pulp are immune cells that participate in the initial recognition and the following processing of antigens triggering pulp defence. ...
... Dental pulp's rich microvasculature and sensory nerve innervation make it a unique tissue. Caries and fractures are the two main reasons that can affect the integrity of the pulp chamber, creating pathways for microorganisms and their metabolites to enter the pulp [1]. The response of the pulp to these afflictions is inflammation, which can spread to the surrounding tissues and alveolar bone [4]. ...
Article
Full-text available
A wide range of mediators are released from the pulp tissue because of bacterial invasion which causes inflammation. Interleukins (ILs) and matrix metalloproteinases (MMPs) have a leading role in initiating and spreading of inflammation because of their synergic action. Biomarkers such as ILs and MMPs can be identified via several methods, establishing the inflammatory response of the dental pulp. The aim of this systematic review is to evaluate the levels of ILs and/or MMPs in human dental pulp. PubMed, OVID, Cochrane, Scopus, Web of Science and Wiley online library databases were searched for original clinical studies. After applying inclusion and exclusion criteria, a quality assessment of studies was performed based on a modified Newcastle-Ottawa scale. In the review were included articles that evaluated the presence of ILs and/or MMPs in pulp tissue using enzyme-linked immunosorbent assay (ELISA) or western blot or multiplex assay. Six articles were included in the present synthesis. Although various diagnostic methods were used, statistically significant higher levels of ILs and/or MMPs were mostly found in the experimental groups compared to healthy pulp samples. The biomarkers studied can be a promising tool to evaluate pulp tissue health or even in pulpitis treatment.
... The increased pressure can also initiate the inflammatory process in periapical tissues. 12 The dental pulp contains nociceptive myelinated A-delta and A-beta nerve fibres and unmyelinated C nerve fibres, which form a plexus of nerves (plexus of Raschkow). 13 The A-delta and A-beta fibres traverse the predentine zone, with their terminal branches entering a short distance into the dentinal tubules. ...
... 16 In pulpitis, as the intra-pulpal pressure continues to rise, there can be complete compression of blood vessels at the apical foramen, resulting in total necrosis. 12 Additionally, the release of intra-cellular lysosomal enzymes by neutrophils are also responsible for the destruction of pulpal tissue and resulting tissue necrosis. 9 Ultimately, there can be a number of irritants other than dental caries, which can result in pulp inflammation and subsequent death such as restoration breakdown, iatrogenic injury, chemical irritation, non-carious tooth tissue loss and trauma. ...
... 9 Ultimately, there can be a number of irritants other than dental caries, which can result in pulp inflammation and subsequent death such as restoration breakdown, iatrogenic injury, chemical irritation, non-carious tooth tissue loss and trauma. 12 The delay in the diagnosis and management of dental caries (both clinically and radiographically) 17 will result in more advanced lesions at first presentation, including those involving the pulp. Lesions with substantial cavitation can adversely affect restorability and increase the requirement for extensive treatment. ...
Article
Full-text available
As routine care was suspended in most countries, one could anticipate progression of undiagnosed and managed oral disease. Patients are usually unaware of the development of oral disease as it is not visible to them and largely asymptomatic, especially in its early stages. The natural progression of conditions such as caries and periodontitis is inevitable without diagnosis and management. The full extent of patient harm because of the suspension of routine dental care can only be estimated when routine oral examinations are fully re-established, and even then, we will probably never know the number of individuals impacted or the extent of disease progression and harm. In first-world countries, there has always been a back-up emergency treatment system for dental problems. For example, in the UK, the safety net for life-threatening swellings and for acute pain relief is the accident and emergency services. This system remained in place during the COVID-19 pandemic. Courts could be expected to understand the coronavirus context and would take this into account should there be a complaint against the clinician about access to care. The suspension of routine dental care to save lives will lead to the closure of many dental practices due to substantial financial impact. The return to routine care will be slow, with prioritisation of non-aerosol generating procedures while we look to further understand methods to mitigate transmission risk via infected aerosol and spatter. Inevitably, the cost of personal protective equipment and the lower volume of patients pose a continued threat to businesses.
... Te ostatnie w przeważającej mierze są przyczyną zapaleń i martwicy miazgi, w tym głównie czynniki bakteryjne (rys. 3.4), termiczne, mechaniczne, chemiczne i elektryczne [4,5]. Istnieje również możliwość zakażenia drogą naczyń krwionośnych, które wnikają do miazgi przez otwór wierzchołkowy. ...
... Odsłonięcie kanalików zębinowych może być wywołane przez czynniki patologiczne, w tym ubytki pochodzenia próchnicowego i niepróchnicowego oraz przez czynniki jatrogenne, czyli wywołane w sposób niezamierzony podczas wykonywania przez lekarza procedur leczniczych. Najczęściej rozwój chorób miazgi powodują drobnoustroje, które penetrują drogą odsłoniętych kanalików zębinowych od strony korony zęba oraz drogą kanalików bocznych i otworu wierzchołkowego od strony zniszczonego przyczepu łącznotkankowego [4,6]. Bakterie przenikają do wnętrza zęba od strony komory wskutek głębokiego ubytku próchnicowego, mikroprzecieku brzeżnego na granicy wypełnienia i twardych tkanek zęba w wyniku próchnicy wtórnej oraz wskutek atrycji, abrazji lub erozji wywołujących ubytki pochodzenia niepróchnicowego. ...
... Ubytki próchnicowe zębiny są spowodowane przez beztlenowce, a także gatunki Gram¬ujemne i paciorkowce [13] penetrujące kanaliki zębinowe, które po dotarciu do miazgi wywołują w niej proces zapalny, a nieleczone -jej martwicę, w której występuje niski poziom tlenu i niski potencjał oksydoredukcyjny sprzyjający zasiedlaniu kolejnych szczepów bakterii bez¬tlenowych [14]. Próchnica zębów w większości krajów wysoko rozwiniętych obejmuje większość dorosłych i 60-90% dzieci szkolnych [10,15] [4,7]. Jedynie 0,1% osób dorosłych w wieku 35-44 lat oraz tylko 19,3% dzieci 12-letnich jest wolnych od próchnicy [8,10]. ...
... This plexus is known as the Plexus of Raschkow. The Plexus of Raschkow is composed of large myelinated nerve fibres (A-δ and A-β fibres, 2 -5 µm in diameter) and small unmyelinated nerve fibres (C fibres, 0.3 -1.2 µm in diameter) (Yu and Abbott, 2007). The myelinated nerve fibres lose their myelin and continue as free nerve endings through the cell-free zone and in-between the odontoblasts. ...
... The pain sensation elicited by the nerve fibres of the dental pulp helps in the early detection of problems, thus protecting the tooth from further damage (Paphangkorakit andOsborn, 1998, Yu andAbbott, 2007). ...
Thesis
Background: There is an unmet need for regenerating functional dental pulp, particularly in non-vital immature permanent teeth where dental pulp necrosis arrests further radicular maturation, putting young patients at risk of tooth loss. Despite the progress achieved over recent decades, dental pulp regeneration still faces challenges in promoting post-implantation vascularisation and inducing odontoblast-like cell differentiation. Aim: The overall aim of the research presented in this thesis was to investigate the potential of a decellularised dental pulp matrix (DDP) of bovine origin to facilitate vascularisation and support dental pulp regeneration. Methods: Bovine dental pulp tissues were retrieved and decellularised. The efficiency of the decellularisation method was evaluated using histological analysis, DNA quantification assay, immunohistochemical staining and scanning electron microscopy. Furthermore, the cytocompatibility of the developed DDPs were assessed using contact and extract cytotoxicity assays. DDPs were then recellularised with human dental pulp stem cells (hDPSCs) and analysed in vitro using scanning electron microscopy, fluorescent staining and confocal scanning laser microscopy, Live/Dead® cells assay, Quant-iT™ PicoGreen® dsDNA assay and histology. The effect of DDPs on gene expression of markers involved in angiogenesis and odontogenesis in hDPSCs was evaluated in vitro using reverse-transcription quantitative polymerase chain reaction (RT-qPCR). A preliminary in vivo study was then conducted in which hDPSCs-seeded and unseeded DDPs were inserted in debrided human premolar root slices and implanted subcutaneously into immunodeficient mice. Samples were retrieved after 30 days and analysed using histological and immunohistochemical staining. Results: Acellular dental pulp matrices retaining the native histoarchitecture, vasculature, essential extracellular matrix components and several growth factors were generated following bovine dental pulp decellularisation. The in vitro cytocompatibility evaluation of the developed DDPs revealed no apparent cytotoxic effect on the growth and morphology of the cells grown in direct contact with the DDPs, and on the viability of cells grown in an extract of DDPs. Upon recellularisation of the DDPs with hDPSCs, the in vitro analyses showed cell engraftment with progressive repopulation of the matrix and vasculature of the DDPs, and with enhanced gene expression of the markers involved in angiogenesis and odontogenesis. In vivo implantation of root slices with hDPSCs-seeded DDPs revealed apparent vascularisation enhancement, whilst those with unseeded DDPs showed host cell recruitment and infiltration. Conclusions: The developed decellularised dental pulp matrix is a cytocompatible, pro-angiogenic and pro-odontogenic scaffold characterised by the retention of native histoarchitecture, vasculature, essential extracellular matrix components and angiogenic and odontogenic growth factors in the matrix following decellularisation. Seeding of hDPSCs onto the DDP led to progressive cell repopulation of the matrix and vasculature, enhanced expression of the markers involved in angiogenesis and odontogenesis in hDPSCs and improved in vivo vascularisation capacity of the DDP. Moreover, the DDP has a chemotactic activity in vivo, enabling host cells mobilisation and recruitment. The findings of this research suggest that a combination of DDP and hDPSCs could provide a promising vascularisation promoting strategy for dental pulp regeneration via cell transplantation. Furthermore, the use of DDP, in its acellular form, could provide a strategy for dental pulp regeneration via cell homing.
... The progression of AP is the gradual spreading of infections from crown-part pulp tissue to root part of the apical papilla. 26 It was recognized that DPCs are the major cells of pulp tissue, which play important roles in selfdefense and repair functions during the progression of pulpitis, 26 while SCAPs reside in apical papilla of immature permanent teeth, which are critical for tooth root development. 4 To further explore the role of pulp inflammatory EVs in AP and tooth root development, we established the in vitro model using DPCs and SCAPs, and subsequently collected the EVs secreted from LPSstimulated DPCs and analyzed their effects on cell viability and odontoblastic differentiation of SCAPs. ...
... The progression of AP is the gradual spreading of infections from crown-part pulp tissue to root part of the apical papilla. 26 It was recognized that DPCs are the major cells of pulp tissue, which play important roles in selfdefense and repair functions during the progression of pulpitis, 26 while SCAPs reside in apical papilla of immature permanent teeth, which are critical for tooth root development. 4 To further explore the role of pulp inflammatory EVs in AP and tooth root development, we established the in vitro model using DPCs and SCAPs, and subsequently collected the EVs secreted from LPSstimulated DPCs and analyzed their effects on cell viability and odontoblastic differentiation of SCAPs. ...
Article
Full-text available
Apical periodontitis (AP) causes arrest of tooth root development, which is associated with impaired odontoblastic differentiation of stem cells from apical papilla (SCAPs), but the underlying mechanism remains unclear. Here, we investigated roles of extracellular vesicle (EV) in AP and odontoblastic differentiation of SCAPs, moreover, a novel nuclear factor I/C (NFIC)-encapsulated EV was developed to promote dentin regeneration. We detected a higher expression of EV marker CD63 in inflamed apical papilla, and found that EVs from LPS-stimulated dental pulp cells suppressed odontoblastic differentiation of SCAPs through downregulating NFIC. Furthermore, we successfully constructed the NFIC-encapsulated EV by overexpressing NFIC in HEK293FT cells, which could upregulate cellular NFIC level in SCAPs, promoting the proliferation and migration of SCAPs, as well as dentinogenesis both in vitro and in vivo. Collectively, based on pathological roles of EV in AP, our study provides a novel strategy for dentin regeneration by exploiting EV to deliver NFIC.
... The dental pulp resides in a highly calcified chamber with a rich neurovascular plexus that modulates several inflammatory chemical mediators [1,2]. Therefore, exposure of the pulp to external factors like microbial infection, mechanical and chemical irritants can cause inflammatory changes at various stages [2]. ...
... The dental pulp resides in a highly calcified chamber with a rich neurovascular plexus that modulates several inflammatory chemical mediators [1,2]. Therefore, exposure of the pulp to external factors like microbial infection, mechanical and chemical irritants can cause inflammatory changes at various stages [2]. Gram-negative bacteria contribute significantly to the clinical manifestations of pulpitis by triggering the expression of inflammatory cytokines [3]. ...
Article
Full-text available
The purpose of the study was to investigate the therapeutic effects of α-lipoic acid (ALA) on an induced-acute pulpitis model in rats. Twenty-four Wistar albino rats were randomly divided into three groups: control, induced-acute pulpitis (PULP) and PULP + ALA groups. In the PULP and PULP + ALA groups, the crowns of the maxillary left incisors were removed horizontally. All exposed pulp tissues were treated with 5 µL LPS solution. In the PULP + ALA group, the rats were treated intraperitoneally with a single dose of ALA (100 mg/kg). The rats were sacrificed 24 h after pulp injury, and the trunk blood and pulp samples were collected and then determined using ELISA assay kits. TNF-α, IL-1β, MMP-1 and MMP-2 levels in the serum and pulp tissues were considerably higher in the PULP group than the control group (p < 0.01–0.001). In the PULP + ALA group, TNF-α, IL-1β, MMP-1 and MMP-2 levels in the serum and pulp tissues decreased significantly compared to the PULP group (p < 0.05–0.001). ALA decreases pro-inflammatory mediators and proteolytic enzymes, which might relieve acute inflammation
... erefore, external stimuli should not generally enter the pulp chamber and cause pulp lesions. Pulpitis is most often caused by infection, which mainly comes from deep caries [4]. Etiologically, pulp disease and periapical disease are broadly similar, for example, severe caries can cause pulpitis, which in turn can cause periapical inflammation [5]. ...
Article
Full-text available
Objective. To evaluate the application of hydrogel scaffold materials and triple antibiotic paste in endodontic regeneration through literature review. Methods. An electronic search of the literature published on PubMed, Wangfang database, and CNKI database using the search terms “endodontic regeneration,” “pulp blood flow reconstruction,” “recanalization,” “triple antibiotic paste,” and “scaffold material” was conducted. The searched literature was used for analysis. Results and Conclusion. Hydrogels regulate stem cell fates, modulate growth factor release, and encapsulate antibacterial and anti-inflammatory drugs. The triple antibiotic paste is composed of metronidazole, ciprofloxacin, and minocycline, which exhibits promising antibacterial effects and duration at appropriate concentrations, with low cytotoxicity, and effectively promotes the preservation and regeneration of pulp tissues and the formation of dental hard tissues. However, issues such as tooth discoloration and bacterial drug resistance also exist. The present article reviews the progress of research on the application of hydrogel scaffold materials and triple antibiotic paste in endodontic revascularization.
... Pulp necrosis can arise mainly from the progression of the untreated inflamed dental pulp and dental trauma, such as luxation and avulsion [31]. Few experimental in vitro, studies have demonstrated that BPs provoke a cytotoxic response in pulp stem cells, decreasing their viability and proliferation, leading to apoptosis [32][33][34]. ...
Article
Full-text available
This systematic review aimed to estimate the prevalence and describe dentoalveolar lesions associated with bisphosphonates therapy. A systematic review of the literature was conducted using the following databases: PubMed, Embase, Cochrane, CINAHL, Scopus, Web of Science, Lilacs, SciElo, and Grey Literature. Quality of individual studies analysis was performed by using Newcastle–Ottawa Scale. Certainty of cumulative evidence was achieved by applying Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. The software R Statistics version 4.0.5 (The R Foundation) was used for proportion estimations per study and corresponding confidence intervals were estimated through the Clopper-Pearson method. Four articles were included for the qualitative synthesis. Two studies were considered of good quality, one of fair, and one of poor quality. A total of 231 patients were encompassed. Widening of the periodontal ligament space (22.2–39.7%), periradicular radiolucencies (20–22.9%), and pulp calcifications (33.3–69.2%) were the most frequent alterations. Certainty of evidence was rated as very low. Based on limited evidence, this systematic review reports a variety of dentoalveolar alterations in patients under bisphosphonate therapy. These features might impact on dental clinical practice. However, the level of evidence is considered very low due to important limitations.
... Pulpitis tissue is located in the dental pulp cavity composed of dentin, tooth enamel, and cementum, which can produce dentin, provide nutrition, and serve a supportive and protective role [1]. In most cases, pathogenic microorganism infection can cause pulpitis and treatments depend on disease severity. ...
Article
Full-text available
Inflammatory reaction of pulp tissue plays a role in the pathogen elimination and tissue repair. The evaluation of severity of pulpitis can serve an instructive function in therapeutic scheme. However, there are many limitations in the traditional evaluation methods for the severity of pulpitis. Based on the Gene Expression Omnibus (GEO) database, our study discovered 843 differentially expressed genes (DEGs) related to pulpitis. Afterwards, we constructed a protein-protein interaction (PPI) network of DEGs and used MCODE plugin to determine the key functional subset. Meanwhile, genes in the key functional subset were subjected to GO and KEGG enrichment analyses. The result showed that genes were mainly enriched in inflammatory reaction-related functions. Next, we screened out intersections of PPI network nodes and pulpitis-related genes. Then, 20 genes were obtained as seed genes. In the PPI network, 50 genes that had the highest correlation with seed genes were screened out using random walk with restart (RWR). Furthermore, 4 pulpitis-related hub genes were obtained from the intersection of the top 50 genes and genes in the key functional subset. Finally, GeneMANIA was utilized to predict genes coexpressed with hub genes, and expression levels of the 4 hub genes in normal and pulpitis groups were analyzed based on GEO data. The result demonstrated that the 4 hub genes were mainly coexpressed with chemokine-related genes and were remarkably upregulated in the pulpitis group. In short, we eventually determined 4 potential biomarkers of pulpitis.
... The primary cause of endodontic pain arises as a result of reactionary response of the pulp tissue to any causative agents like dental caries or other irritants. The pulp tissue is shown to respond to various external stimuli like dental caries, trauma or even conventional restorative procedures [30]. The progression of bacteria within the canal plays a pivotal role in pain progression. ...
... The dental pulp is a specialized loose connective tissue, densely innervated and vascularized, enclosed in a rigid environment comprising three mineralized tissues: dentin, enamel, and cementum, which provide it mechanical support and protection against the microbial environment of the oral cavity [1]. The main functions of the pulp are regeneration, repair, as well as defense, through specialized cells of the immune system that help to maintain homeostasis through the formation of dentin, caused by various factors [2], which can induce inflammation of the pulp tissue [3]. ...
Article
Full-text available
The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.
... The dogma that claims severe pulp inflammation is irreversible, is based on the assumption that the pulp has limited ability to recover from the infectious and inflammatory challenge due to the anatomical constraint of its low compliance environment and lack of collateral circulation (62). However, the dental pulp possesses anatomical and physiological properties that may help compensate for these limitations. ...
Article
Full-text available
Research over several decades has increased our understanding of the nature of reparative and regenerative processes in the dental pulp, at both the cellular and molecular level. However, advances in scientific knowledge have not translated into novel clinical treatment strategies for caries-induced pulpitis. This narrative review explores the evidence regarding the ability of inflamed pulp tissue to heal and how this knowledge may be used therapeutically. A literature search and evidence analysis covering basic, translational and clinical pulp biology research was performed. The review focuses on (1) the regenerative and defense capabilities of the pulp during caries-induced inflammation; (2) the potential of novel biomaterials to harness the reparative and regenerative functions of the inflamed pulp; and (3) future perspectives and opportunities for conservative management of the inflamed pulp. Current conservative management strategies for pulpitis are limited by a combination of unreliable diagnostic tools and an outdated understanding of pulpal pathophysiological responses. This approach leads to the often unnecessary removal of the entire pulp. Consequently, there is a need for better diagnostic approaches and a focus on minimally-invasive treatments utilizing biologically-based regenerative materials and technologies.
... Dental pulp, a highly organized soft tissue situated in a confined environment surrounded by dentin walls, plays a seminal role in maintaining tooth homeostasis. 1 However, the dental pulp is prone to irreversible pulpitis or necrosis resulting from dental traumas and infections. 2 The traditional therapeutic intervention, known as root canal therapy, is based on infected dental pulp extirpation and bioinert material root canal filling resulting in a devitalized tooth, which is more vulnerable to reinfections and fractures. 3 In recent years, the development of stem cell-based regenerative medicine has shown immense potential for tooth viability restoration and pulp regeneration. ...
Article
Full-text available
Objectives Pulp regeneration brings big challenges for clinicians, and vascularization is considered as its determining factor. We previously accomplished pulp regeneration with autologous stem cells from deciduous teeth (SHED) aggregates implantation in teenager patients, however, the underlying mechanism needs to be clarified for regenerating pulp in adults. Serving as an important effector of mesenchymal stem cells (MSCs), exosomes have been reported to promote angiogenesis and tissue regeneration effectively. Here, we aimed to investigate the role of SHED aggregate-derived exosomes (SA-Exo) in the angiogenesis of pulp regeneration. Materials and Methods We extracted exosomes from SHED aggregates and utilized them in the pulp regeneration animal model. The pro-angiogenetic effects of SA-Exo on SHED and human umbilical vein endothelial cells (HUVECs) were evaluated. The related mechanisms were further investigated. Results We firstly found that SA-Exo significantly improved pulp tissue regeneration and angiogenesis in vivo. Next, we found that SA-Exo promoted SHED endothelial differentiation and enhanced the angiogenic ability of HUVECs, as indicated by the in vitro tube formation assay. Mechanistically, miR-26a, which is enriched in SA-Exo, improved angiogenesis both in SHED and HUVECs via regulating TGF-β/SMAD2/3 signalling. Conclusions In summary, these data reveal that SA-Exo shuttled miR-26a promotes angiogenesis via TGF-β/SMAD2/3 signalling contributing to SHED aggregate-based pulp tissue regeneration. These novel insights into SA-Exo may facilitate the development of new strategies for pulp regeneration.
... The mechanism of inward or outward movement of tubular fluid leads to the direct mechanism of deformation. 8 These abrupt changes in the temperature between the teeth and restorative interface by any process of activation may cause vulnerable effects on the pulp tissue. A small rise in intrapulpal temperature-induced lead to histological evidence of pulpitis of differing severity irrespective of the method of heat stimuli. ...
... Many cellular functions of the tooth are concentrated in the dental pulp [1,2]. The proteome represents the current functional status of a tissue. ...
Article
Full-text available
Objectives The aim of this investigation was the detailed analysis of the human pulp proteome using the new picosecond infrared laser (PIRL)-based sampling technique, which is based on a completely different mechanism compared to mechanical sampling. Proteome analysis of healthy pulp can provide data to define changes in the proteome associated with dental disease. Material and methods Immediately after extraction of the entire, undamaged tooth, 15 wisdom teeth were deep frozen in liquid nitrogen and preserved at −80°C. Teeth were crushed, and the excised frozen pulps were conditioned for further analysis. The pulps were sampled using PIRL, and the aspirates digested with trypsin and analyzed with mass spectrometry. Pulp proteins were categorized according to their gene ontology terminus. Proteins identified exclusively in this study were searched in the Human Protein Atlas (HPA) for gaining information about the main known localization and function. Results A total of 1348 proteins were identified in this study. The comparison with prior studies showed a match of 72%. Twenty-eight percent of the proteins were identified exclusively in this study. Considering HPA, almost half of these proteins were assigned to tissues that could be pulp specific. Conclusion PIRL is releasing proteins from the dental pulp which are not dissolved by conventional sampling techniques. Clinical Relevance The presented data extend current knowledge on dental pulp proteomics in healthy teeth and can serve as a reference for studies on pulp proteomics in dental disease.
... Some of the hypotheses to explain the presence of these microorganisms in previously healthy tooth who suffered APN are: 1. they are caused by bacteria of the oral cavity via gingival sulcus; 2. by exposed dentinal tubules; 3. by cracks in enamel; or 4. they come from some distant site of infection in the body, reaching the pulp via a hematogenous route 21.22 . When bacteria find the necrotic pulp tissue, they multiply more easily, quickly developing a periapical infection 23 . Even though most studies that investigated bacterial colonization secondary to APN have occurred in teeth that have suffered trauma, they are still the basis for postulating the same mechanism in patients with SCD or SCT and who have suffered APN from specific vaso-occlusive phenomena. ...
... 36 Multiple microbial infections in the root canal system caused by disruption of enamel integrity or periapical contamination may lead to inflammation of the pulp and periradicular tissues. 37 Severe odontogenic pain and necrosis of the tissue are the main signs and symptoms of the disease. In general, immediate procedures to access the pulp chamber and debride the root canal system are necessary to mitigate pain and control the inflammation response. ...
Article
The coronavirus disease 2019 (Covid-19) is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that clinically affects multiple organs of the human body. Cells in the oral cavity express viral entry receptor angiotensin-converting enzyme 2 that allows viral replication and may cause tissue inflammation and destruction. Recent studies have reported that Covid-19 patients present oral manifestations with multiple clinical aspects. In this review, we aim to summarise main signs and symptoms of Covid-19 in the oral cavity, its possible association with oral diseases, and the plausible underlying mechanisms of hyperinflammation reflecting crosstalk between Covid-19 and oral diseases. Ulcers, blisters, necrotising gingivitis, opportunistic coinfections, salivary gland alterations, white and erythematous plaques and gustatory dysfunction were the most reported clinical oral manifestations in patients with Covid-19. In general, the lesions appear concomitant with the loss of smell and taste. Multiple reports show evidences of necrotic/ulcerative gingiva, oral blisters and hypergrowth of opportunistic oral pathogens. SARS-CoV-2 exhibits tropism for endothelial cells and Covid-19-mediated endotheliitis can not only promote inflammation in oral tissues but can also facilitate virus spread. In addition, elevated levels of proinflammatory mediators in patients with Covid-19 and oral infectious disease can impair tissue homeostasis and cause delayed disease resolution. This suggests potential crosstalk of immune-mediated pathways underlying pathogenesis. Interestingly, few reports suggest recurrent herpetic lesions and higher bacterial growth in Covid-19 subjects, indicating SARS-CoV-2 and oral virus/bacteria interaction. Larger cohort studies comparing SARS-CoV-2 negative and positive subjects will reveal oral manifestation of the virus on oral health and its role in exacerbating oral infection.
... Dental pulp is a soft tissue comprising nerves, blood vessels, lymphatic vessels, connective tissue, and various types of cells within a tooth [1]. Moreover, it includes several antibacterial substances, hormones, and immune cells that protect the teeth from external invasive bacteria or irritants and prevent the accumulation of extrinsic bacteria or substances inside the dental pulp [2,3]. ...
Article
Full-text available
FK866 possesses various functional properties, such as anti-angiogenic, anti-cancer, and anti-inflammatory activities. We previously demonstrated that premature senescence of human dental pulp cells (hDPCs) was induced by hydrogen peroxide (H2O2). The present study aimed to investigate whether H2O2-induced premature senescence of hDPCs is affected by treatment with FK866. We found that FK866 markedly inhibited the senescent characteristics of hDPCs after exposure to H2O2, as revealed by an increase in the number of senescence-associated β-galactosidase (SA-β-gal)-positive hDPCs and the upregulation of the p21 and p53 proteins, which acts as molecular indicators of cellular senescence. Moreover, the stimulatory effects of H2O2 on cellular senescence are associated with oxidative stress induction, such as excessive ROS production and NADPH consumption, telomere DNA damage induction, and upregulation of senescence-associated secretory phenotype factors (IL-1β, IL-6, IL-8, COX-2, and TNF-α) as well as NF-κB activation, which were all blocked by FK866. Thus, FK866 might antagonize H2O2-induced premature senescence of hDPCs, acting as a potential therapeutic antioxidant by attenuating oxidative stress-induced pathologies in dental pulp, including inflammation and cellular senescence.
... The blood flow to the injured tooth is affected due causing ischemic necrosis, followed by pulp necrosis. 6 The diagnosis of dental pulp necrosis requires an X-Ray to visualize the tooth. Ice-cold and hot tests are used to examine the nerve sensation. ...
Article
Full-text available
Dental pulp necrosis is referred to the situation in which the teeth biologically die due to bacterial infection or without bacterial infection. Dental pulp necrosis can be due to a chronic progression of pulpitis, in which the tissue of soft pulp in the tooth dies due to several causes such as trauma or severe bacterial infection. Untreated cavities, multiple invasive treatments for the tooth, and pathological ischemia for dental pulp are among the most common causes for the necrosis process. Usually, the first symptom of dental pulp necrosis is the irritant pain in the tooth only or the surrounding area because of the inflammation. The grade of pain ranges from mild, moderate, to severe pain according to the size of the damage, followed by swelling and discomfort in chewing due to the pressure on the nerve root at the base of the tooth. We aim to review the different etiologies, risk factors, correlations, and clinical outcomes associated with pulp necrosis. To our knowledge, this article is going to be the first comprehensive review of dental pulp necrosis.
... The particular maxillary artery leads into the dental artery, which is supply the tooth by the arterioles nourishing each distinct pulp microvasculature. The vessels of the pulp are organized in a hierarchical system (Yu and Abbott, 2007). ...
Thesis
Full-text available
Background: Dental bleaching represents most of the clinical procedures frequently demanded by patients. Although clinical studies have shown that inoffice bleaching can reach a pleasing degree of whitening, it showed an adverse effect on tooth structure and especially in the pulp tissue. It causes different degree of damage with release of neuropeptide that represents the major role in the development and maintenance of dental pain and inflammation. Aims of the study: To evaluate the inflammatory response and tissue organization of dental pulp chamber in rats after in-office bleaching procedure with two bleaching products different in concentration of hydrogen peroxide by histological and immunohistochemical assessment for Substance P. Materials and methods: Twenty four male rats (albino type) were divided randomly into two groups (n=12), in the first group the right maxillary molars were treated with single session of 40% of hydrogen peroxide (2×20 minute) while the second group the right maxillary molars were treated with single session of 30% of hydrogen peroxide (3×15 minute) and the left maxillary molars in both bleached groups were received no treatment (control group).Then each group was divided into two sub groups according to the time of scarification: 1day and 7days after bleaching treatment(n=6), and the jaw was processed for histological (hematoxylin and eosin stain) and immunohistochemical analysis for Substance P in pulp tissue. Results: Both bleached groups showed statistically significant differences regarding the pulp inflammation and tissue organization when compared with control group. At 1 day duration most specimens in 40% bleached group exhibited focal areas of necrosis and disorganized tissue within the pulp chamber while in 30% bleached group showed pulp tissue with mild and moderate inflammation and disorganized tissue with few of the specimensAbstract IV revealed necrosis. At 7 days duration most specimens of both bleached groups demonstrated a characteristic of tissue repair. The immunohistochemical results at 1day duration showed higher mean value of the number of dental pulp cells that positively expressed for Substance P antibody in both ble
... Histopathological results after 8 days of operation indicated a mild inflammatory reaction beneath the cavity site and this was resolved by day 30. Yu et al. suggested that although dilated vessels can indicate active dentinogenesis, this observation may also suggest an inflammatory reaction within the tissue that may affect pulp healing and regeneration as the intensity of the stimulus increases or decreases [54]. In the current study, S-PRG/Li-100 mM showed a transient increase in the number of blood vessels with no statistical difference when compared to other groups; in addition, the number of blood vessels declined gradually by the end of the trial. ...
Article
Full-text available
Objective Surface pre-reacted glass fillers (S-PRG) can release different types of ions and in our previous study, we modified these fillers with lithium chloride (S-PRG/Li-100 mM) to induce reparative dentin formation by activating the Wnt/β-catenin signaling pathway. Here, we assessed the biological performance of S-PRG/Li-100 mM and compared it with that of mineral trioxide aggregate (MTA) and S-PRG without additives. Methods In vivo studies were conducted on male Wistar rats using Masson’s trichrome staining in pulp-capped molars. The test materials were implanted subcutaneously to evaluate their capacity for vascularization and biocompatibility. The ability of the test materials to form apatite was tested by immersing them in simulated body fluid. Rhodamine-B staining was conducted to assess their sealing ability in bovine teeth, while their antibacterial activity was evaluated against Streptococcus mutans and Lactobacillus casei in terms of colony-forming units and by live/dead staining. Results Masson’s trichrome staining and tissue-implantation tests confirmed the biocompatibility of S-PRG/Li-100 mM and it was similar to that of MTA and S-PRG; inflammation regression was observed 14 days after operation in the subcutaneous tissues. S-PRG/Li-100 mM promoted the formation of apatite on its surface. Both the S-PRG groups showed higher sealing capability and bactericidal/bacteriostatic activity against oral bacterial biofilms than MTA. Significance Lithium-containing surface pre-reacted glass cements exhibit better antibacterial and sealing capabilities than MTA, suggesting their potential as high-performance direct pulp-capping materials.
... However, until now, only the pulp has been clinically regenerated, which may be due to the applied young SHED aggregates and the natural shape of the pulp cavity, while the results of a recent clinical trial using autologous healthy PDLSCs derived from the impacted tooth are not satisfactory (18,23). Of note, pulpitis is a localized disease that is rarely affected by persistent host factors, and the pulp cavity confers physical protection for pulp regeneration (64). Other than pulpitis, however, periodontal lesions lack protective space for stem cell function and are closely linked to systemic inflammation, which may partially explain the difficulty in their regeneration. ...
Article
Full-text available
The treatment of chronic periodontitis is undergoing a transition from simple plaque removal and replacement with substitute materials to regenerative therapy, in which stem cells play an important role. Although stem cell-based periodontal reconstruction has been widely explored, few clinical regeneration studies have been reported. The inflammatory lesions under the impact of host factors such as local microbial–host responses, may impede the regenerative properties of stem cells and destroy their living microenvironment. Furthermore, systemic diseases, in particular diabetes mellitus, synergistically shape the disordered host-bacterial responses and exacerbate the dysfunction of resident periodontal ligament stem cells (PDLSCs), which ultimately restrain the capacity of mesenchymal stromal cells (MSCs) to repair the damaged periodontal tissue. Accordingly, precise regulation of an instructive niche has become a promising approach to facilitate stem cell-based therapeutics for ameliorating periodontitis and for periodontal tissue regeneration. This review describes host limitations and coping strategies that influence resident or transplanted stem cell-mediated periodontal regeneration, such as the management of local microbial–host responses and rejuvenation of endogenous PDLSCs. More importantly, we recommend that active treatments for systemic diseases would also assist in recovering the limited stem cell function on the basis of amelioration of the inflammatory periodontal microenvironment.
... Dental pulp is a kind of vascularized and innervated tissue that could maintain homeostasis and physiological vitality of teeth by transporting oxygen and nutrients [1]. A series of serious consequences such as pulpitis, apical periodontitis, and tooth extraction could be caused by losing pulp viability after pulp exposure [2,3]. ...
Article
Full-text available
Background and Objectives: Human dental pulp cells (HDPCs) can be used for dentin regeneration due to its odontogenic differentiation property. Icariin can induce osteogenic differentiation of stem cells. However, its potential to induce odontogenic differentiation of HDPCs remains unclear. Thus, the aim of this study was to evaluate the capacity of icariin to induce odontogenic differentiation of HDPCs and investigate the underlying molecular mechanism. Materials and Methods: Cell viability assay was used to detect the cytotoxicity of icariin to HDPCs. Effect of icariin on HDPCs chemotaxis was measured by scratch migration assay. The mineralized and odontogenic differentiation of HDPCs was assessed by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, real-time PCR, and Western blot of dentin matrix protein 1 (DMP 1) and dentin sialophosphoprotein (DSPP). In addition, Mitogen-activated protein kinase (MAPK) signaling pathway of icariin-induced biomineralization was investigated by Western blot. Results: Cells treated with icariin at all concentrations tested maintained viability, indicating that icariin was biocompatible. Icariin accelerated HDPCs chemotaxis (p < 0.05). Expression levels of related odontogenic markers were increased in the presence of icariin (p < 0.05). Icariin-induced odontogenic differentiation occurred via activation of the MAPK signaling pathway. Furthermore, MAPK inhibitors suppressed expression levels of DSPP and DMP 1 protein, ALP activity, and mineralization of HDPCs. Conclusions: Icariin can upregulate odontogenic differentiation of HDPCs by triggering the MAPK signaling pathway.
... 47 The pulpdentin complex is a specialized neurovascular connective tissue encased within mineralized tissues that maintain the vitality of natural teeth and is susceptible to trauma, inflammation, and infections with limited regenerative capabilities. 48 A large number of patients present to dental offices with significant tooth decay, necessitating either direct or indirect placement of a pulp capping (protective) agent such as Calcium hydroxide, Mineral Trioxide Aggregate (MTA), and Biodentine, among others. 49 These agents induce the pulp-dentin complex to deposit a reparative mineralized tissue termed Osteodentin. ...
Article
Full-text available
The major difference between tissue healing and regeneration is the extent of instructional cues available to precisely direct the biological response. A classic example is reparative or osteodentin that is seen in response to physicochemical injury to the pulp-dentin complex. Dentin regeneration can direct the differentiation of dental stem cells using concerted actions of both soluble (biomolecules, agonists, and antagonists) and insoluble (matrix topology) cues. The major purpose of this study was to examine the synergistic combination of two discrete biomaterial approaches by utilizing nanofiber scaffolds in discrete configurations (aligned or random) with incorporated polymeric microspheres capable of controlled release of growth factors. Further, to ensure appropriate disinfection for clinical use, Radio-Frequency Glow Discharge (RFGD) treatments were utilized, followed by seeding with a mesenchymal stem cell (MSC) line. SEM analysis revealed electrospinning generated controlled architectural features that significantly improved MSC adhesion and proliferation on the aligned nanofiber scaffolds compared to randomly oriented scaffolds. These responses were further enhanced by RFGD pre-treatments. These enhanced cell adhesion and proliferative responses could be attributed to matrix-induced Wnt signaling that was abrogated by pre-treatments with anti-Wnt3a neutralizing antibodies. Next, we incorporated controlled-release microspheres within these electrospun scaffolds with either TGF-β1 or BMP4. We observed that these scaffolds could selectively induce dentinogenic or osteogenic markers (DSPP, Runx2, and BSP) and mineralization. This work demonstrates the utility of a novel, modular combinatorial scaffold system capable of lineage-restricted differentiation into bone or dentin. Future validation of this scaffold system in vivo as a pulp capping agent represents an innovative dentin regenerative approach capable of preserving tooth pulp vitality.
... In deep carious lesions, microorganisms and their metabolic by-products could pass through the dentinal tubules and irritate the dental pulp even without direct contact with dental pulp tissue. These toxins are one of the major factors that cause reversible or irreversible damage to the pulp [39]. These irritants in carious lesions invoke dental pulp's inflammatory response [40]. ...
Article
Full-text available
Objective This study aims to review systematically the dental pulp response to silver diamine fluoride (SDF) treatment, including the inflammatory response, pulp cells activity, dentinogenesis, silver penetration, and the presence of the bacteria in the dental pulp. Data In vitro studies, animal studies, clinical studies, and case reports on the use of SDF on vital dental pulp were included. Quality assessment of the included studies was conducted. A narrative synthesis of the collected data was performed. Sources A systematic search was performed in ProQuest, PubMed, SCOPUS, and Web of Science databases for articles published from inception to Nov 1, 2021. Study Selection The initial search identified 1,433 publications, of which five publications met the inclusion criteria. These five publications reported the effect of direct/ indirect SDF application on the vital pulp of a total of 30 teeth. Direct SDF application on vital pulp caused pulp necrosis. Indirect SDF application caused none or mild inflammatory response of dental pulp. The odontoblasts in the dental pulp showed increased cellular activity. Tertiary dentine was formed in the pulpal side of the cavity with indirect SDF application. Accentuated incremental lines of tertiary dentine reflected disturbances in mineralisation. Silver ions were found to penetrate along the dentinal tubules but were not detected inside the pulp. Conclusion According to the limited available literature, direct SDF application causes pulp necrosis. Indirect SDF application is generally biocompatible to dental pulp tissue with a mild inflammatory response, increased odontoblastic activity, and increased tertiary dentine formation. Future studies with precise quantitative and qualitative tests, larger sample size and longer follow-up time are imperative to understand the biological activity of dental pulp to SDF treatment.
... Caries includes interactions between the bacterial biofilm and the surface of teeth, saliva, and genes, dietary carbohydrates, including sugars and starches, and the interaction of behavioral, social, and psychological factors [11][12][13]. The overwhelming majority of the causes of pulp inflammation and necrosis are extrinsic factors, which include bacterial, thermal, mechanical, chemical, and electrical factors [14,15]. There is also a possibility of infection through the blood vessels that penetrate the pulp through the apical opening. ...
Article
Full-text available
A very extensive literature review presents the possibilities and needs of using, in endodontics, the alloys commonly known as nitinol. Nitinol, as the most modern group of engineering materials used to develop root canals, is equilibrium nickel and titanium alloys in terms of the elements’ atomic concentration, or very similar. The main audience of this paper is engineers, tool designers and manufacturers, PhD students, and students of materials and manufacturing engineering but this article can also certainly be used by dentists. The paper aims to present a full material science characterization of the structure and properties of nitinol alloys and to discuss all structural phenomena that determine the performance properties of these alloys, including those applied to manufacture the endodontic tools. The paper presents the selection of these alloys’ chemical composition and processing conditions and their importance in the endodontic treatment of teeth. The results of laboratory studies on the analysis of changes during the sterilization of endodontic instruments made of nitinol alloys are also included. The summary of all the literature analyses is an SWOT analysis of strengths, weaknesses, opportunities, and threats, and is a forecast of the development strategy of this material in a specific application such as endodontics.
... The rate of dentin deposition is a physiologic process that not only depends on tooth type, location and age (Arora et al., 2016;Marron et al., 2017;Philippas, 1961) but is also subject to individual variation and can be influenced by environmental effects or trauma. Comparing both sides can reveal different rates of dentine deposition caused by unilateral local stress or (minor) trauma (Hale, 2020;Kuttler, 1959;Yu & Abbott, 2007). As for all age estimation methods, individual variation should be accounted for and the margins of the estimated age range should therefore be wide enough. ...
Article
Full-text available
Age estimation in adult dogs can be performed by the radiographic measurement of the tooth pulp cavity, but the technique has hardly been described. In this study, the application of measuring pulp/tooth width ratios (P/T ratios) of the maxillary canine teeth was investigated. Pulp and tooth widths were measured at two locations on 166 maxillary canine teeth of the heads of 84 dog cadavers, using digital extraoral lateral oblique open mouth radiographs. The dogs belonged to different breeds and sexes and had a known age between 194 and 1907 days (approximately 6 months ‐ 5 years). Both at the cemento‐enamel junction (CE) and the half‐height of the tooth, a comparable non‐linear regression with age was demonstrated. Measuring at the CE location was less hindered by wear or superimposition. No statistically significant difference according to sex and breed size and no clinically significant difference according to skull type was found. The highest predictable capacity was found in the youngest dogs until the age of 448 days, of which 84.4% of the canine teeth had a P/T ratio above 0.39. Our results demonstrate that measuring P/T ratios of canine teeth can be used in practice to assign dogs to age categories, with the highest accuracy in young adult dogs.
... However, the intent of the paper is to present the investigation as an example of the many differing parameters for a clinician to consider; some discussion has been made to identify some of these issues, without necessarily attempting a direct consequence of the in vitro investigation. The extrapolation to in vivo conditions is to be handled with care, as too many factors apply by way of pulp blood flow, tooth condition, size, age, etc. [41,42]. ...
Article
Full-text available
Background: During in-office bleaching, appropriate light sources are applied in order to enhance the activity of the bleaching gels applied onto teeth. For this method to be effective, a high absorption of light within the gel is necessary. Variation in the light attenuation capability of the gel, the duration of application and light activation can contribute towards safety hazards associated with this procedure. Methods: In this study, seven different gels and hydrogen peroxide have been evaluated for their optical properties by means of spectrophotometry (440-1000 nm). The transmitted light spectrum was used to estimate the intensity loss for each gel. The mean intensity decreases observed were statistically analysed using an analysis of variance (ANOVA). Results: The five more-pigmented gels tested indicated a very similar intensity loss of around 80%, whereas the remaining two gels showed significantly less attenuation (predominantly, p < 10-6). Conclusions: Throughout the spectrum of wavelengths examined, and according to the underlying studies evaluated, five of the gels assessed demonstrated an attenuation high enough to possibly avoid overheating of the underlying enamel dentine and pulp. An evaluation of appropriate irradiation parameters is proposed.
Article
Dental pulp stem cells (DPSCs) from pulpitis patients showed defective osteogenic differentiation. However, as the most well-studied histone acetyltransferase, the impaired general control nonrepressed protein 5 (GCN5) plays essential roles in various developmental processes. The aim of this study was to investigate the effect of GCN5 on DPSCs odontogenic differentiation. The healthy dental pulp tissues were obtained from the extracted impacted third molar of patients with the informed consent. DPSCs were treated with a high concentration of tumor necrosis factor-alpha (TNF-α) (100 ng/mL) and odontogenic differentiation-related gene and GCN5 protein level by Western blot analysis. Proliferation of the DPSCs was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Immunofluorescence staining detected GCN5 and NF-κB signaling for p-p65. The mechanism of GCN5 regulating odontogenic differentiation of DPSCs was determined by small interfering RNA analysis. Our data suggested that TNF-α can significantly reduce mineralization and the expression of dentin matrix acidic phosphoprotein 1 and dentin sialophosphoprotein at higher concentration (100 ng/mL). Meanwhile, it showed that the inflammation in microenvironment resulted in a downregulation of GCN5 expression and GCN5 knockdown caused decreased odontogenic differentiation of DPSCs was also found. In addition, the knockdown of GCN5 increased the expression of phosphorylation of p65, thus activating NF-κB pathway of DPSCs. Meanwhile, NF-κB pathway inhibitor pyrrolidinedithiocarbamic acid reversed the siGCN5 decreased odontogenic differentiation of DPSCs. Altogether, our findings indicated that in inflammatory microenvironments GCN5 plays a protective role in pulpitis impaired odontogenic differentiation of DPSCs by activating NF-κB pathway, which may provide a potential approach to dentin regeneration.
Article
Full-text available
Capillary liver hemangioma is a frequent finding during routine ultrasound examination, while hemangioma with focal cirrhosis, in a form of isolated liver tumor is rather rare. The finding of pedunculated liver tumor morphologically defined as a combination of cirrhotic liver tissue surrounding capillary hemangioma, is a unique case in our clinical practice. A case of 44-years-old female patient, with left liver lobe tumor incidentally found by ultrasound, is presented. The unexpected microscopic finding of cirrhotic tissue in the tumor specimen obtained with fine needle biopsy under ultrasound control, was confirmed by second biopsy. Because etiological, clinical and biochemical findings supporting the diagnosis of cirrhosis were absent, another fine needle biopsy of the right liver lobe was performed, revealing a normal liver histology. Since contrast enhanced Computed Tomography (CT) confirmed the presence of pendulous tumor, the patient underwent abdominal surgery and tumor resection. Histological analysis of surgical specimen revealed the presence of capillary hemangioma surrounded by cirrhotic liver tissue. The presence of liver tumors can be easily detected by “imaging methods” such as ultrasound and contrast�enhanced CT, but only biopsy specimen can determine the real nature of the lesion. Microscopic finding obtained from operative specimen compared to histological finding of specimen obtained by percutaneous fine needle biopsy is superior in determining the diagnosis of focal liver lesions. Key words: liver tumor, focal cirrhosis, FNH, capillary hemangioma, histology
Article
Full-text available
Introduction Dental pulp fibroblasts (DPF) are the most abundant cell type in the dental pulp. They play pivotal roles; however, they are often mistaken to be involved only in the repair and maintenance of this connective tissue. Methods We used the search terms “pulp fibroblast,” “complement system proteins,” “pulp inflammation,” “angiogenesis,” and “dentin pulp regeneration” to identify articles from the PubMed and Scopus databases. Result These sentinel cells produce all complement system proteins participating in defense processes, control of inflammation, and dentin-pulp regeneration; produce several proinflammatory cytokines and chemokines and express pattern-recognition receptors, demonstrating their involvement in immunoregulatory mechanisms; express neuropeptides and their receptors, playing an important role in neurogenic inflammation and dental pulp wound healing; secrete angiogenic growth factors as well as neurotrophic proteins, essential for dentin-pulp regeneration; regulate neuronal plasticity processes; and can sense the external environment. Conclusion This review highlights that DPFs are more than mere passive cells in pulp biology and presents an integrative analysis of their roles and functions.
Article
As the fourth state of matter, plasma’s unique properties and interactions with other states of matter offer many promising opportunities for investigation and discovery. In particular, cold atmospheric plasma (CAP), operating at atmospheric pressure and room temperature, has remarkable potential for biomedical applications through various delivery methods. These biomedical applications include sterilization, wound healing, blood coagulation, oral/dental diseases treatment, cancer therapy, and immunotherapy. Effective delivery of plasma constituents is critical to its efficacy for these applications. Therefore, this review presents the key research activities related to CAP delivery (including direct CAP delivery, delivery of plasma-activated media, biomedical device-assisted plasma delivery, and CAP delivery with other therapeutics) and needs for future research. This review will be of great interest for understanding the current state-of-the-art of biomedical applications of plasma medicine while also giving researchers from a broad range of communities insight into research efforts that would benefit from their contributions. Such communities include biomedicine, physics, biochemistry, material science, nanotechnology, and medical device manufacturing.
Article
Thermal and electric pulp sensibility tests are commonly used by the majority of clinicians when diagnosing endodontic disease. These tests indirectly determine the state of pulpal health by assessing the response of the Aδ nerve fibres within the pulp-dentine complex. A positive response to sensibility testing indicates that the nerve fibres are functioning but does not give any quantitative information on nerve function, pulpal blood flow or histological status of the dental pulp. These tests have inherent limitations, including a reliance on a patient's subjective response to the test and the dentist's interpretation of the patient's response. This two-part series aims to help clinicians to reach an accurate endodontic diagnosis by providing an overview of how to undertake common pulpal sensibility tests correctly, how to interpret their results and understand their limitations. This section provides an overview of pulp testing, definitions of terminology relevant to pulp testing, the diagnostic uses of pulp testing and a summary of the diagnostic accuracy of different pulp tests. Provides a background overview of pulp testing and a summary of the 'jigsaw' of information a clinician may put together when making an endodontic diagnosis.Outlines terminology relevant to pulp testing and their definitions.Provides a summary of the diagnostic uses of pulp testing and the diagnostic accuracy of common pulp tests used in clinical practice. Provides a background overview of pulp testing and a summary of the 'jigsaw' of information a clinician may put together when making an endodontic diagnosis. Outlines terminology relevant to pulp testing and their definitions. Provides a summary of the diagnostic uses of pulp testing and the diagnostic accuracy of common pulp tests used in clinical practice.
Article
Full-text available
Dental pulp vitality is a desideratum for preserving the health and functionality of the tooth. In certain clinical situations that lead to pulp exposure, bioactive agents are used in direct pulp-capping procedures to stimulate the dentin-pulp complex and activate reparative dentinogenesis. Hydraulic calcium-silicate cements, derived from Portland cement, can induce the formation of a new dentin bridge at the interface between the biomaterial and the dental pulp. Odontoblasts are molecularly activated, and, if necessary, undifferentiated stem cells in the dental pulp can differentiate into odontoblasts. An extensive review of literature was conducted on MedLine/PubMed database to evaluate the histological outcomes of direct pulp capping with hydraulic calcium-silicate cements performed on animal models. Overall, irrespective of their physico-chemical properties and the molecular mechanisms involved in pulp healing, the effects of cements on tertiary dentin formation and pulp vitality preservation were positive. Histological examinations showed different degrees of dental pulp inflammatory response and complete/incomplete dentin bridge formation during the pulp healing process at different follow-up periods. Calcium silicate materials have the ability to induce reparative dentinogenesis when applied over exposed pulps, with different behaviors, as related to the animal model used, pulpal inflammatory responses, and quality of dentin bridges.
Article
Full-text available
Aim To create an irreversible pulpitis gene signature from microarray data of healthy and inflamed dental pulps, followed by a bioinformatics approach using connectivity mapping to identify therapeutic compounds that could potentially treat pulpitis. Methodology The Gene Expression Omnibus (GEO) database, an international public repository of genomics datasets, was searched for human microarray datasets assessing pulpitis. An irreversible pulpitis gene expression signature was generated by differential expression analysis. The statistically significant connectivity map (ssCMap) method was used to identify compounds with a highly correlating gene expression pattern. qPCR was used to validate novel pulpitis genes. An ex vivo pulpitis model was used to test the effects of the compounds identified, and the level of inflammatory cytokines was measured with qPCR, ELISA and multiplex array. Means were compared using the t‐test or ANOVA with the level of significance set at p≤0.05. Results Pulpitis gene signatures were created using differential gene expression analysis at cutoff points p=0.0001 and 0.000018. Top upregulated genes were selected as potential pulpitis biomarkers. Among these, IL8, IL6 and MMP9 were previously identified as pulpitis biomarkers. Novel up‐regulated genes; chemokine (C‐C motif) ligand 21 (CCL21), metallothionein 1H (MT1H) and aquaporin 9 (AQP9) were validated in the pulp tissue of teeth clinically diagnosed with irreversible pulpitis using qPCR. ssCMap analysis identified fluvastatin (Statin) and dequalinium chloride (Quaternary ammonium) as compounds with the strongest correlation to the gene signatures (p=0.0001). Fluvastatin reduced IL8, IL6, CCL21, AQP9 (p<0.001) and MMP9 (p<0.05) in the ex‐vivo pulpitis model, while dequalinium chloride reduced AQP9 (p<0.001) but had no significant effect on the other biomarkers. Conclusions AQP9, MT1H and CCL21 were identified and validated as novel biomarkers for pulpitis. Fluvastatin and dequalinium chloride identified by the ssCMap as potential therapeutics for pulpitis reduced selected pulpitis biomarkers in an ex vivo pulpitis model. In vivo testing of these licensed drugs is warranted.
Article
Introduction Many studies have investigated the transcriptome profiles of dental stem cells for regenerative medicine. However, such studies use bulk RNA and do not consider cell-level heterogeneity. Here, we investigated the characteristics and heterogeneity of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs) at the single-cell level and examined the differences between them. Methods HDPSCs and hPDLSCs were obtained from caries-free premolars (n = 2). scRNA-seq of hDPSCs and hPDLSCs was performed using a DOLOMITE droplet microfluidic device and the Illumina NextSeq550 system. Data alignment was performed using STAR v2.4.0, and further analysis was performed using ‘Seurat,’ ‘singleR,’ and ‘clusterProfiler,’ packages in R. Results HDPSCs and hPDLSCs were separated into three clusters. hDPSCs mainly exhibited osteogenic and neurogenic cell populations. The main populations of hPDLSCs comprised osteogenic and myofibroblastic populations. hPDLSCs showed high ‘scores’ for osteogenic gene expression whereas hDPSCs had high neurogenic and endogenic ‘scores’. Conclusions Single-cell RNA sequencing of hDPSCs and hPDLSCs revealed that the genes expressed in specific clusters. The results of these analyses can be used as reference databases and valuable resources for further research in dental therapeutics.
Article
Full-text available
Objective: Since the 1960s, there has been contradictory evidence regarding the association between periodontal pathology and the status of the pulp. The purpose of this study was to evaluate the histopathological changes of pulp tissue with severe periodontal disease, including vertical bone loss involving the major apical foramen, and compared them with the histological pulpal status of teeth with healthy periodontium. Methods: This case-controlled study included 35 intact teeth with severe periodontitis of hopeless prognosis (test group) and 35 teeth without periodontitis extracted for orthodontic reasons (control group). For each tooth, periodontal and endodontic parameters such as probing depth and pulpal vitality were recorded, and the pulp tissue was evaluated histologically. The data were analysed with a significance level of 0.05. Results: Vital pulp was observed in all specimens of both groups (P=1). Pulpal inflammation in the apical portion was observed in 81.71% of the severe periodontitis group, whereas all teeth in the control group demonstrated no signs of pulpal inflammation. Dystrophic calcification and pulp stones were observed in 7.5% of the periodontitis group and 5.7% of the healthy group (P>0.05). Pulp fibrosis was observed in 22.8% of the periodontitis group and 2.8% of the control group (P=0.012). Pulpal necrosis was not noted in either group. In the periodontitis group, internal resorption was present in 22.8% of cases (P=0.005) and external resorption was present in 80% of cases (P<0.001). In the control group, no internal or external resorption was observed in any of the specimens. No differences were noted in the study patients with regard to sex or age. Conclusion: Periodontal disease does not significantly affect pulp vitality and pulpal calcifications. However internal and/or external resorption was significantly different between the two groups as well as apical inflammation and pulp fibrosis.
Article
Pulpitis is the inflammatory response of the dental pulp to a tooth insult, whether it is microbial, chemical, or physical in origin. It is traditionally referred to as reversible or irreversible, a classification for therapeutic purposes that determines the capability of the pulp to heal. Recently, new knowledge about dental pulp physiopathology led to orientate therapeutics towards more frequent preservation of pulp vitality. However, full adoption of these vital pulp therapies by dental practitioners will be achieved only following better understanding of cell and tissue mechanisms involved in pulpitis. The current narrative review aimed to discuss the contribution of the most significant experimental models developed to study pulpitis. Traditionally, in vitro two(2D)- or three(3D)-dimensional cell cultures or in vivo animal models were used to analyse the pulp response to pulpitis inducers at cell, tissue or organ level. In vitro 2D cell cultures were mainly used to decipher the specific roles of key actors of pulp inflammation such as bacterial by-products, pro-inflammatory cytokines, odontoblasts or pulp stem cells. However, these simple models did not reproduce the 3D organisation of the pulp tissue and, with rare exceptions, did not consider interactions between resident cell types. In vitro tissue/organ-based models were developed to better reflect the complexity of the pulp structure. Their major disadvantage is that they did not allow the analysis of blood supply and innervation participation. On the contrary, in vivo models have allowed researchers to identify key immune, vascular and nervous actors of pulpitis and to understand their function and interplay in the inflamed pulp. However, inflammation was mainly induced by iatrogenic dentine drilling associated with simple pulp exposure to the oral environment or stimulation by individual bacterial by-products for short periods. Clearly, these models did not reflect the long and progressive development of dental caries. Lastly, the substantial diversity of the existing models makes experimental data extrapolation to the clinical situation complicated. Therefore, improvement in the design and standardization of future models, for example by using novel molecular biomarkers, databased models and artificial intelligence, will be an essential step in building an incremental knowledge of pulpitis in the future.
Article
The dentin-pulp complex is a unique structure in teeth that contains both hard and soft tissues. Generally, deep caries and trauma cause damage to the dentin-pulp complex, and if left untreated, this damage will progress to irreversible pulpitis. The aim of this study was to fabricate a layered cell sheet composed of rat dental pulp (DP) cells and odontogenic differentiation of pulp (OD) cells and to investigate the ability to regenerate the dentin-pulp complex in a scaffold tooth. We fabricated two single cell sheets composed of DP cells (DP cell sheet) or OD cells (OD cell sheet) and a layered cell sheet made by layering both cells. The characteristics of the fabricated cell sheets were analyzed using light microscopy, scanning electron microscopy (SEM), hematoxylin-eosin (HE) staining, and immunohistochemistry (IHC). Furthermore, the cell sheets were transplanted into the subrenal capsule of immunocompromised mice for 8 weeks. Following this, the regenerative capacity to form dentin-like tissue was evaluated using micro-computed tomography (Micro-CT), HE staining, and IHC. The findings of SEM and IHC confirmed that layered cell sheets fabricated by stacking OD cells and DP cells maintained their cytological characteristics. Micro-CT of layered cell sheet transplants revealed a mineralized capping of the access cavity in the crown area, similar to that of natural dentin. In contrast, the OD cell sheet group demonstrated the formation of irregular fragments of mineralized tissue in the pulp cavity, and the DP cell sheet did not develop any hard tissue. Moreover, bone volume/tissue volume (BV/TV) showed a significant increase in hard tissue formation in the layered cell sheet group compared to that in the single cell sheet group (p<0.05). HE staining also showed a combination of soft and hard tissue formation in the layered cell sheet group. Furthermore, IHC confirmed that the dentin-like tissue generated from the layered cell sheet expressed characteristic markers of dentin but not bone equivalent to that of a natural tooth. In conclusion, this study demonstrates the feasibility of regenerating dentin-pulp complex using a bioengineered tissue designed to simulate the anatomical structure.
Article
Introduction Transient receptor potential ankyrin-1 (TRPA1) and vanilloid-1 (TRPV1) are thermo-sensitive channels that play an important role in thermal sensation or tooth pain by regulating intracellular Ca²⁺ concentration that is essential for pulp tissue repair. The aim of this study was to evaluate the role of TRPA1 and TRPV1 channels in odontogenic differentiation of human dental pulp cells (HDPCs). Methods HDPCs were isolated from healthy human intact third molars and cultured in odontogenic differentiation medium. Gene and protein expression levels of TRPA1 and TRPV1 channels during the odontogenic differentiation of HDPCs were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. HDPCs were then treated with channel agonists or antagonists and expression levels of odontogenic markers dentine sialophosphoprotein (DSPP) and osteopontin (OPN) were examined. Alkaline phosphatase activity and alizarin red staining were also conducted to detect mineralization levels. Results Consistent with the mineralization degree and DSPP and OPN expression, mRNA and protein expression of TRPA1 and TRPV1 channels were upregulated during the odontogenic differentiation of HDPCs. The application of TRPA1 or TRPV1 agonists increased the mineralized nodules of alizarin red staining and alkaline phosphatase activity and upregulated the mRNA and protein expression of DSPP and OPN, respectively, with the highest values reached on the 7th day (P < 0.05). On the contrary, mineralization level and DSPP and OPN expression could be suppressed by using the antagonists of these two channels. Conclusions TRPA1 and TRPV1 channels not only showed upregulated expression along with the odontogenic differentiation of HDPCs, but could affect the odontogenic differentiation by regulating intracellular Ca²⁺ concentration.
Article
Introduction This study assessed the influence of voxel size and filter application in detecting second mesiobuccal (MB2) canals in cone-beam computed tomographic (CBCT) images. Methods Using the OP300 CBCT system (Instrumentarium, Tuusula, Finland) and 3 voxel size protocols (80 μm, 125 μm, and 200 μm), we scanned 40 first molars: 20 with an MB2 canal and 20 without. All molars received silver palladium pins on the palatal root, whereas the non-MB2 molars were also filled with gutta-percha. Five oral radiologists assessed the presence of an MB2 canal under 3 filter application conditions: without filter, with sharpen 1 × filter, and with sharpen 2 × filter. Intra- and interobserver reproducibility was evaluated using the weighted kappa index. We compared the area under the receiver operating characteristic curves with SPSS Statistics v.20.0 (IBM Corp, Armonk, NY) using 2-way analysis of variance and the Tukey post hoc test with 5% significance level. Results Our analysis found median intra- and interobserver agreement values of 0.70 and 0.56, respectively. The 80-μm voxel with sharpen 1 × filter image group had the highest sensitivity, accuracy, and negative predictive values. As for specificity and positive predictive, the 80-μm voxel group without filter application presented the highest values. The areas under the receiver operating characteristic curve were higher in the 80-μm groups than in the 125-μm and 200-μm voxel size groups (P < .05). We found no differences among the filters used (P = .22) or for the filter–voxel size interactions (P = .88). Conclusions A smaller voxel size increased the accuracy in detecting MB2 canals, whereas the enhancement filters did not.
Article
Introduction: Pulp stones are the discrete calcification, located in pulp tissue or attached to or embedded in dentin. It occurs in physiological and pathological conditions. The exact etiopathogenesis of various types of pulp calcifications is unknown and the prevalence varies from 8% to 90%. The histopathological identification of pulp stones is higher than the radiological identification. Objective: The aim of the study is to evaluate and correlate the clinical parameters and histopathological analysis of pulp stone with systemic hypertension and hyperlipidemia. Materials and methods: Seventy patients were selected for the study and a detailed case history was recorded. The radiological investigations were noted down and extirpated pulp tissues were sent for processing. The results were analyzed statistically using Chi-square test. Results: Out of 70 patients studied, pulp stones were observed radiologically in 14 patients and histopathologically in 30 patients. The presence of irregular and nonlaminated type of pulp stones histopathologically was significantly correlated with hypertension and hyperlipidemia. Conclusion: The patients with the histopathological presence of nonlaminated and irregular-shaped pulp should be evaluated for lipid profile and hypertension.
Article
Aim To evaluate if treatment with resiniferatoxin (RTX) is capable of lowering the plasma levels of PGE2 and TNF-α, as well as histopathological parameters in inflammation of pulp tissue in a mouse experimental model. Methodology Ten groups of six BALB/c mice were formed as follows: healthy group (HC), healthy group treated with RTX (HRTX), two groups with pulp inflammation at 14 and 18 hours (PI14/PI18); six groups with pulpal inflammation plus treatment with Ibuprofen (IBU14/IBU18), dexamethasone (DEX14/DEX18) and resiniferatoxin (RTX14/RTX18) at 14 and 18 hours, respectively. Pulpal inflammation was induced through occlusal exposure of the pulp of the maxillary first molar. The plasma levels of PGE2 and TNF-α and the histological parameters of the pulp tissue of the HC and HRTX groups were evaluated at the time of acquiring the animals. In the other groups, the plasma levels of PGE2 and TNF-α and the histopathological parameters were evaluated at 14 and 18 hours after pulp damage. Plasma levels of PGE2 and TNF-α were quantified by ELISA assay and the histopathological parameters were evaluated by H/E staining. Statistical significance was determined by one-way analysis of variance (ANOVA) to test for overall differences between group means. Results A significant increase (*p<0.05) in plasma levels of PGE2 and TNF-α occurred 14 and 18 hours after pulp damage. In addition, treatment with RTX significantly decreased (*p<0.05) the plasma levels of PGE2 and TNF-α at 14 and 18 hours after pulp damage, as well as the infiltrate of inflammatory cells at 18 hours after pulp damage, similarly to treatment with ibuprofen and dexamethasone. Conclusion It was possible to detect systemic levels of PGE2 and TNF-α at 14 and 18 hours after pulp damage. Likewise, treatment with RTX was associated with an anti-inflammatory effect similar to treatment with ibuprofen and dexamethasone. These findings place resiniferatoxin as a therapeutic alternative in the treatment of inflammatory diseases in Dentistry.
Chapter
Despite the self-healing capacity of the dental pulp complex, threatening circumstances, such as dental caries, trauma, and fracture, may considerably compromise tooth vitality, leading to inflammation of the pulp and ultimately pulp necrosis. Thus there are several biologically driven approaches, such as vital pulp therapy and pulp revascularization treatment, that may stimulate the damaged pulp tissue to recover its properties, although none of these approaches comprise a true regenerative process. Recently, numerous strategies have been introduced to regenerate artificial dental tissues, ranging from cell homing methods that use the resident stem cells that already exist in the periapical area of the host, to repopulating the damaged tissue to cell-laden (cell transplantation) methods that may only induce regenerative outcomes by enriching the root canal system with exogenous stem cells. More importantly, specialized three-dimensional engineered constructs that mimic the hierarchical structure of the dental-pulp complex have been demonstrated, bringing the field of regenerative endodontics for the first time to a closer level of clinical translation of tooth regeneration. The foregoing aspects are the focus of this chapter, which presents the current status of regenerative endodontics and the possible paths for future research in the field.
Article
Full-text available
The paper is an extensive monographic review of the literature, and also uses the results of the authors’ own experimental research illustrating the noticed developmental tendencies of the filling material based on gutta-percha. The whole body of literature proves the correctness of the research thesis that this material is the best currently that can be used in endodontics. Caries is one of the most common global infectious diseases. Since the dawn of humankind, the consequence of the disease has been the loss of dentition over time through dental extractions. Both tooth caries and tooth loss cause numerous complications and systemic diseases, which have a serious impact on insurance systems and on the well-being, quality, and length of human life. Endodontic treatment, which has been developing since 1836, is an alternative to tooth extraction. Based on an extensive literature review, the methodology of qualifying patients for endodontic treatment was analyzed. The importance of selecting filling material and techniques for the development and obturation of the root canal during endodontic treatment was described. Particular attention was paid to the materials science aspects and the sequence of phase transformations and precipitation processes, as well as the need to ensure the stoichiometric chemical composition of Ni–Ti alloys, and the vacuum metallurgical processes and material processing technologies for the effects of shape memory and superelasticity, which determine the suitability of tools made of this alloy for endodontic purposes. The phenomena accompanying the sterilization of such tools, limiting the relatively small number of times of their use, play an important role. The methods of root canal preparation and obturation methods through cold side condensation and thermoplastic methods, including the most modern of them, the thermo-hydraulic condensation (THC) technique, were analyzed. An important element of the research hypothesis was to prove the assumption that to optimize the technology of development and obturation of root canals, tests of filling effectiveness are identified by the density and size of the gaps between the root canal wall, and the filling methods used and devices appropriate for material research, using mainly microscopy such as light stereoscopic (LSM) and scanning electron (SEM). The most beneficial preparations were obtained by making a longitudinal breakthrough of 48 natural human teeth, extracted for medical reasons, different from caries, with compliance with all ethical principles in this field. The teeth were prepared using various methods and filled with multiple obturation techniques, using a virtual selection of experimental variants. The breakthroughs were made in liquid nitrogen after a one-sided incision with a narrow gap created by a diamond disc using a materialographic cutter. The best effectiveness of the root canal filling was ensured by the technology of preparing the root canals with K3 rotary nitinol tools and filling the teeth with the THC thermoplastic method using the System B and Obtura III devices with studs and pellets of filling material based on gutta-percha after covering the root canal walls with a thin layer of AH Plus sealant. In this way, the research thesis was confirmed.
Article
Introduction: Dental caries is a chronic infectious disease resultingfrom the penetration of oral bacteria into tooth hard tissues.Microorganisms subsequently trigger inflammatory responsesin the dental pulp and the stem cells provide a source of cells toreplace the damaged cells and facilitate repair. These events canlead to pulp healing if the infection is not too severe and treatedin a short time. Remaining pulpal pathosis in severe form withouttreatment induces permanent loss of normal tissue due to limitedrepair capacities in response to large damage. The importanceof the depth of inflammation has been underestimated in pulpalhealing. The purpose of this study is to investigate the pulp tissueresponse to dental caries and to find out the association of differentdistributions of the inflammatory characteristics among a differentdepth of dental caries. Materials and Methods: Pulp tissue sampleswere collected from 118 extracted teeth from the Privet dental clinicsand dental health centers in Duhok government, from April/ 2016 toAugust/ 2017 (16 months period). Each section prepared and stainedwith hematoxylin and Eosin (H&E). Inflammatory infiltration, fibrosis, calcification, and necrosis were the main features that have beenexamined histopathologically and assessed with the presence of dentalcaries at a different depth. Results and Discussion: Inflammatoryfeatures were identified in 88 of the samples examined. Inflammatory infiltration and fibrosis were the most frequent features amongthe deep caries teeth compared to the shallow caries teeth. Single andgroup of calcification were observed in 57 samples, most of them (48samples) were in deep caries sections. Conclusion: the histopathological observations of pulp tissue in response to caries process provideuseful information for the clinical aspect and how to decide and selectthe best strategy in the treatment of dental caries at a different depthto preserve the pulp tissue vitality for a longer time, and strength ofthe tooth hard tissue will maintain.
Chapter
Complete regeneration of dental pulp tissue is the main focus of procedures in regenerative endodontics. The two major strategies currently under exploration are tissue engineering-based pulp regeneration and pulp revascularization. The pulp regeneration strategies based on tissue engineering rely on three key elements: autologous/exogenous dental stem cells, bioactive scaffolds, and signaling molecules. In these approaches, either the exogenous stem cells are in vitro expanded and transplanted or signaling molecules and/or bioactive scaffolds are used as cues to recruit endogenous stem/progenitor cells into the root canal system. Through either of approaches, the differentiation of stem cells into odontoblast-like cells is expected in order to facilitate the pulp-like tissue formation. Rapid vascularization is of paramount importance in the survival and integration of engineered pulp tissue. Incorporation of pre-fabricated microvascular networks into the engineered tissue constructs could promote immediate connection with the host circulation following implantation. Additionally, endothelial cells derived from dental stem cells could be used in vasculature engineering that will greatly contribute to dental pulp regeneration. In parallel to the tissue engineering approaches, regenerative endodontic procedures (REPs), which focus on dental pulp revascularization, have become a part of routine endodontic clinical practice. REPs mainly include three steps: disinfection, evoking blood into the root canal, and achievement of a coronal seal. Several clinical trials have reported favorable outcomes with this technique in relation to necrotic immature teeth. However, histological studies have shown that tissues formed in the root canal space are cementum, periodontium, and bone-like tissues rather than pulp–dentin complex. Further studies, therefore, are required to optimize the conditions that could promote natural dentin/pulp-complex-like tissue regeneration.
Article
Full-text available
Mechanisms of blockade of tetrodotoxin-resistant (TTXr) Na+ channels by local anesthetics in comparison with the sensitivity of tetrodotoxin-sensitive (TTXs) Na+ channels were studied by means of the patch-clamp technique in neurons of dorsal root ganglions (DRG) of rat. Half-maximum inhibitory concentration (IC50) for the tonic block of TTXr Na+ currents by lidocaine was 210 micromol/l, whereas TTXs Na+ currents showed five times lower IC50 of 42 micromol/l. Bupivacaine blocked TTXr and TTXs Na+ currents more potently with IC50 of 32 and 13 micromol/l, respectively. In the inactivated state, TTXr Na+ channel block by lidocaine showed higher sensitivities (IC50 = 60 micromol/l) than in the resting state underlying tonic blockade. The time constant tau1 of recovery of TTXr Na+ channels from inactivation at -80 mV was slowed from 2 to 5 ms after addition of 10 micromol/l bupivacaine, whereas the tau2 value of approximately 500 ms remained unchanged. The use-dependent block of TTXr Na+ channels led to a progressive reduction of current amplitudes with increasing frequency of stimulation, which was </=53% block at 20 Hz in 10 micromol/l bupivacaine and 81% in 100 micromol lidocaine. The functional importance of the use-dependent block was confirmed in current-clamp experiments where 30 micromol/l of lidocaine or bupivacaine did not suppress the single action potential but clearly reduced the firing frequency of action potentials again with stronger potency of bupivacaine. Because it was found that TTXr Na+ channels predominantly occur in smaller sensory neurons, their blockade might underlie the suppression of the sensation of pain. Different sensitivities and varying proportions of TTXr and TTXs Na+ channels could explain the known differential block in spinal anesthesia. We suggest that the frequency reduction at low local anesthetic concentrations may explain the phenomenon of paresthesia where sensory information are suppressed gradually during spinal anesthesia.
Article
Full-text available
The ultrastructure of nerves containing immunoreactivity for calcitonin gene-related peptide (CGRP) was investigated in the dental pulp of rat molars. The immunoreactivity was recognized predominantly in unmyelinated nerve fibers, and sparsely in a few myelinated fibers. It was localized throughout the axoplasm, as well as in the large cored vesicles. Small clear vesicles and mitochondria were free of the immunoreaction. The CGRP-immunoreactive nerves were frequently observed to terminate, being devoid of Schwann cell investment, in the vicinity of blood vessels in the coronal pulp, suggesting that CGRP may be involved in the regulation of pulpal blood flow. Moreover, CGRP-immunoreactive axon terminals containing numerous small clear vesicles, a few large cored vesicles and mitochondria were recognized in contact with the cell bodies of odontoblasts and their processes in the dentinal tubules. Although specialized synaptic ultrastructures were not recognizable, a functional association of CGRP nerves and odontoblasts was suggested. Thus, CGRP in the dental pulp appears to have multiple functions, including vascular regulation and sensory transduction.
Article
Changes in systemic hemodynamic parameters have a profoundeffect on pulpal hemodynamics. The optimum Hct range for the transport rate of O2 to the pulp is between 35% and 55%. The pulpal circulation has relatively lower resistance and higher flow in comparison with the systemic circulation on a per unit weight basis. Pulpal blood flow is sensitive to sympathetic nerve activity which causes vasoconstriction.
Article
Incipient carious lesions were examined by the SEM technique with the purpose of demonstrating the invasion of microorganisms under lesions without cavitation on the enamel surface. Microorganisms were seen to penetrate fairly deeply into the lesions. In some cases, they reached the dentino-enamel (DE) junction before any cavitation of the surface had ocurred. A gap between the enamel and the dentin could be completely filled with microorganisms. In some advanced attacks there was not only lateral spread of infection along the DE junction, but also outward (retrograde caries) as well as pulpward destruction, even before cavitation on the surface. Microorganisms seemed to be capable of removing enamel structures by direct action in a way similar to that of osteoclasts dissolving bone.Copyright © 1980 S. Karger AG, Basel
Article
Invasive cervical resorption is an insidious and often aggressively destructive form of external root resorption which may occur as a late complication following dental trauma particularly where it involves damage to cementum and supporting tissues. While this resorption may be evident clinically as a pink coronal discolouration, later with cavitation of the enamel, often there are no obvious external signs and the condition is only detected radiographically. It is characterised by the invasion of the cervical region of the root by fibrovascular tissue which progressively resorbs dentine, enamel and cementum. The dental pulp remains protected by an intact layer of dentine and predentine until late in die process. Ectopic calcifications can be observed in advanced lesions both within the invading fibrous tissue and deposited directly onto the resorbed dentine surface.
Article
Gnotobiotic rats mono-infected with Streptococcus mutans (NCTC 10919) were maintained on a high sucrose diet in an isolator. When they were 8 weeks old the pulps of their maxillary first and second molars were mechanically exposed and left open to the oral environment. The rats were sacrificed in groups after 7 and 28 days. Thirty-seven teeth were available for study in the 7-day group, and 30 teeth in the 28-day group. The test S. mutans was non-cariogenic. After 7 days, necrosis of the superficial layers of the pulp was noted; however, after 28 days pulpal necrosis was much more extensive and calcific repair was observed in only one-third of the teeth examined. The microorganism did not provoke inflammation in the pulp or periapical tissues. This is the second strain of S. mutans tested in this manner. These results are very similar to those reported previously for S. mutans (NCTC 10449) and strengthens the view that organisms of the S. mutans group have a low pathogenicity for the pulp.
Article
Differentiation of odontoblasts involves cell-to-cell recognition, contact stabilization involving the formation of attachment specializations, cytoplasmic polarization, development of the protein synthetic and secretory apparatus, and the active transport of mineral ions. The secretory odontoblast is characterized by an extensive rough-surfaced endoplasmic reticulum, a highly developed Golgi complex, and the presence of specific secretion granules. Type I collagen, a major constituent of dentin matrix, appears to be secreted by the odontoblast into predentin at the proximal portion of the odontoblast process, the major cytoplasmic process extending from the odontoblast cell body into the dentin. The odontoblast process contains a rich network of microtubules and microfilaments. The proximal portion of the process is also a site of fluid-phase endocytosis. Adjacent odontoblasts are held together by numerous macula adherens junctions and a well-developed distal junctional complex adjacent to the predentin. Junctional strands of the occludens type have been observed to be a component of this junctional complex. Tracer studies employing horse-radish peroxidase indicate that this junctional complex does not form a tight barrier to the diffusion of tissue fluid from the interodontoblast spaces into the predentin. Many well-developed gap junctions are formed between adjacent odontoblasts and between odontoblasts and the fibroblasts that make up the subodontoblastic layer. Ca-ATPase activity is demonstrated in the Golgi complex and mitochondrial cristae and along the distal plasma membranes of odontoblasts. ALPase activity is also intense along the entire odontoblast cell surface. The osmium tetroxide-pyroantimonate technique for calcium localization demonstrates prominent reaction precipitates in mitochondria of odontoblasts. Energy-dispersive x-ray microanalysis of anhydrously fixed and processed odontoblasts detected Ca and P peaks throughout the cytoplasm. A sulfur peak is noted in the distal cytoplasm of odontoblasts and in matrix vesicles. Together, these results demonstrate the complexity and variety of cell functions involved in dentinogenesis. © 1996 Wiley-Liss, Inc.
Article
While endodontic (dentoalveolar) abscesses can cause significant morbidity, in susceptible individuals they can pose life-threatening problems. This paper provides an overview of the more serious sequelae of endodontic abscesses, and provides examples of ‘high risk’ situations in practice in which these serious complications are more likely to occur.
Article
Infection of the root canal system following dental trauma induces pulp and periapical disease and prevents healing of previously healthy pulp. A clinical goal in treating trauma is the maintenance of pulp vitality, and clinicians should be aware of factors that influence pulp healing. The learning objective of this article is to review the factors and techniques that influence pulp vitality and examine the influence pulp has on the healing of adjacent tissues. The potential routes for bacterial infection of the root canal system are discussed, with the clinical crown as the primary portal of entry. Uncomplicated and complicated crown fractures, as well as the crown-root and root fractures, are reviewed. Complications in pulp healing include canal obliteration, disturbed root development, apexogenesis, apexification, and the various forms of resorption.
Article
The effect of somatostatin on nerve-induced vasodilatation and the release of substance P (SP) was studied in the dental pulp of anesthetized cats. Changes in pulpal blood flow were determined by measuring the rate of disappearance of a local depot of radioactive tracer. The release of SP was studied indirectly by determining the residual amounts of substance P-like immunoreactivity (SPLI) in the pulps by radioimmunoassay. Electrical stimulation (3 min at 10 V, 15 Hz and 5 ms) of the distal end of the cut inferior alveolar nerve (IAN) increased pulpal blood flow. After pretreatment (10 min) with somatostatin (30 pmol/min) similar nerve stimulation was without effect on pulpal blood flow. Intra-arterial infusion of somatostatin (30 pmol/min) had no effect on pulpal blood flow and did not influence the vasodilator response to SP. Following IAN stimulation (3--45 min) and subsequent incubation (30 min, 37 degrees C) of the lower canine teeth, the SPLI levels in ipsilateral pulps were significantly lower (47.5% reduction) than those in contralateral, unstimulated controls. In cats pretreated with somatostatin (30 pmol/min for 10 min, i.a.) similar nerve stimulation (3 min) did not reduce the pulpal SPLI levels as compared to controls. The results show that nerve-induced vasodilatation and release of SPLI are inhibited by somatostatin. They are consistent with the hypothesis that vasodilatation in the cat dental pulp produced by stimulation of the IAN is mediated by substance P.
Article
Extirpated pulps showing a scarlet-red granular background with scattered pyknotic nuclei represent the early degenerative changes of an ischemic infarction. Occlusion of the apical vessels from sudden trauma leads to ischemia, the breakdown of capillary walls, the escape of erythrocytes, and the eventual conversion of hemoglobin to red granular debris which permeates the pulp tissue. One hundred fifty cases are presented with specific posttrauma time intervals ranging from 20 hours to ten years. Two cases presented similar findings after orthodontic therapy.
Article
Dental examples are given (e.g. referred pain, V neuralgia) which exemplify the multifactorial and puzzling nature of pain. Pain results from a noxious stimulus activating some of the small-diameter myelinated and unmyelinated afferent nerve fibres that innervate skin, mucosa, teeth etc. It is complex experience including the sensation experienced as well as the emotional, cognitive and motivational reactions evoked by the stimulus. Pain is not a simple function of the magnitude of damage caused by the stimulus, but also depends on factors such as the person's emotions, past experience of pain, and other concomitant sensory experiences (e.g. with acupuncture). Early postulates of pain failed to take all these factors into account. In the V system (Fig. 1), the specificity theory would maintain that there exists a 'private pain path' from oral-facial tissues to the cerebral cortex, with nerve fibres and brain cells in this path responsive only to stimulu of a noxious character (Fig. 2). But anatomical, physiological and psychological observations have failed to give full support to this theory and other postulates of pain. Although some details of the more recently proposed gate control theory have not been sustantiated, this theory has provided a good general framework for viewing pain and has stimulated much recent research. It emphasizes sensory interaction between large and small-diameter afferent nerve fibres in the gate control system, and regulation over central pain transmission through the gate by descending central controls (Fig. 3). In the V system, brain cells involved in central pain transmission have now been found (Fig. 4), and sensory interactions and descending controls on these brain cells noted (Fig. 5). Neural mechanisms such as these have been implicated in pain, and in its control by procedures such as acupuncture, suggestion, distraction and narcotic analgesia.
Article
Noncarious teeth obtained from individuals 15 to 50 years of age were used to study the lymphatic drainage of the human pulp. Thick sections (50 to 150 microns) were stained with iron hematoxylin for the demonstration of lymph and blood vessels. Lymph capillaries originated as blind sacs in the odontoblastic layer and in the pulp proper near the pulpo-odontoblastic border. They drained into small thin-walled collecting vessels that were irregular in shape and showed great variability in their drainage patterns. Communications between these vessels were very common. The larger conducting lymphatic vessels accompanied the blood vessels and nerves in their course through the pulp. They could be identified by their thin walls and small size. The large caliber lymphatic vessels contained valves, a structure not present in the veins of the same size. The conducting lymphatic vessels passed through the roots as individual units without draining into a large single vessel. The lymphatic vessels of the human pulp must be considered as a pathway for the removal of excessive tissue fluid in normal and diseased pulps.
The following case illustrates an unusual response by the dental pulp to caries in an immunodeficient patient. The patient, a 14-year-old boy, suffered from thymic dysplasia and IgA deficiency. Deep dentinal caries produced relatively little destruction of the pulp and only a mild inflammatory response, in spite of the presence of a large number of bacteria in the pulp chamber. The patient's immunologic disorder was diagnosed as hereditary combined immunodeficiency of unknown type. However, it may have been a variant of Nezelof's syndrome.
Article
Pulpal blood flow was determined in 32 dogs ranging in age from 6 weeks to 18 months by the isotope fractionation method incorporating diffusible and nondiffusible tracers. Dogs were placed into selected age groups by the developmental status of the canine teeth. For the teeth sampled, the maxillary first, second, and third incisors along with the canines and first molars, pulpal blood flow was determined to be not different in teeth at various developmental stages. For some dental pulps, alveolar mucosa, and bone, the tracers were not determining equivalent blood flows. Because of incomplete trapping of the 7- to 10 mu microspheres and the flow limitation of 86Rb, the 15 mu spheres would appear to be a reliable indicator of "total" blood flow to pulpal tissues. However, in alveolar mucosa and bone, and 15 mu microspheres may not be completely trapped and thus, may underestimate blood flow to these tissues. Within the age range of these dogs, tissue blood flow was not dependent upon the stages of oral development.
Article
Culture filtrates (extracellular components) and material obtained from disintegrated cells (intracellular components) of cultured plaque bacteria were studied for their capacity to induce inflammatory reactions in the dental pulp. Class V cavities were prepared on the buccal surface of 94 teeth: 42 test and 52 control teeth in six adult monkeys. lyophilized bacterial components were sealed into the test cavities either alone or following an 8-h topical application of a solution of the same components in phosphate-buffered saline (PBS). Culture medium and PBS were applied in two sets of control cavities. A third set was restored with zinc oxide-eugenol cement. The animals were killed 32 h after the initiation of the experiment and the pulps were examined histologically. Teeth treated trophil leukocytes in the area of the pulp subjacent to the cut dentin tubules. Abscess formation was frequently found. The severe reactions which developed were independent of differences between individual animals and differences in thickness of the remaining dentin. The controls showed damage to the odontoblasts but little or no neutrophil infiltration. The findings confirm that products of bacteria applied to exposed dentin initiate inflammatory reactions in the dental pulp.
The present investigation was undertaken to determine possible quantitative changes in porcine pulpal histamine levels following thermal and electrical insult. Quantitative spectrophotofluorometric assays revealed a fourfold increase in pulpal histamine levels within 30 minutes of thermal injury. These findings suggest that histamine may play a role in the initial stages of pulpal inflammation. Electrical insult was found to have no significant effect on pulpal histamine contents 30 minutes after insult. The possible implications of these findings are discussed.
Article
Nonerupted, young functional, and old noncarious teeth obtained from individuals who varied in age from 15 to 75 years were studied to determine the changes in the collagenous fibers and ground substance during the aging process. It was noted that in the aging process, there is a progressive reduction in the size of the pulpal chamber and a progressive deposition of calcified masses that originate in the root pulp and progress into the coronal pulp. As a result of the calcification of the blood vessels and nerves in the pulp, there is a decrease in the number of blood vessels and nerves in the coronal pulp. However, their connective tissue sheaths persist and give the pulp a fibrotic appearance. The stroma of the pulp, regardless of age, consists of fine collagenous fibers and an abundant amount of alcianophilic ground substance.
Article
Blood flow in the external cartoid artery (ECBF) and dental pulp (PBF) was measured during arterial infusion of vasodilators (isoprenaline, papaverine, acetylcholine and bradykinin). Systemic arterial pressure (AP) and local arterial pressure of the teeth (LAP) were recorded in a femoral and the lateral nasal artery respectively. All four vasodilators were found to increase ECBF and simultaneously reduce lateral nasal arterial pressure--or in other words-to STEAL" PERFUSION PRESSURE FROM THE TEETH. AP remained practically unchanged whereas PBF was variably affected. During infusion of isoprenaline PBF decreased on average by 19% of control. Papaverine nearly doubled PBG, while bradykinin caused no consistent change. Great pulpal flow variations were often recorded during constant acetylcholine infusion rate. The variable effect of the four vasodilators on PBF could partly be explained by the fall in LAP. Calculated pulpal resistance (LAP/PBF) showed no consistent change during isoprenaline infusion, bradykinin caused a slight fall and papaverine reduced LAP/PBF by 49%. The experiments demonstrate that due to the "stealing" of dental perfusion pressure caused by vasodilation in the neighbouring tissues, the effect of vasodilators on pulpal resistance vessels cannot be estimated without knowledge of the pressure in the small arteries directly feeding the teeth.
Article
The greatest cause of endodontic and periapical pathosis is microbial infection of the pulp. Most odontogenic infections are of a polymicrobial nature. With advances in anaerobic isolation and culturing techniques, much has been learned about the presence of pathogenic organisms such as Porphyromonas and Prevotella species (formerly classified as black-pigmented Bacteroides species) in infected root canals. This review provides a summary of recent developments in endodontic microbiology, virulence factors, and host defense systems as they relate to the pathogenesis of pulpal and periapical inflammatory lesions.
Article
Immunoglobulin molecules in the supernatant fluids (SF) from pulpal explant cultures have been observed to react with microorganisms implicated in infections of root canals. In this study, the reactivity of immunoglobulin molecules in the SF from normal and irreversible pulpitis pulps to six strains of predominant microorganisms isolated from the immediate layer of carious lesions above the pulps used for explant cultures was investigated using an enzyme-linked immunosorbent assay. Two ATCC strains of Eubacterium were also included in this assay. Specific antibodies to Lactobacillus casei subsp. casei, Lactobacillus casei subsp. rhamnosus, Lactobacillus acidophilus (I), (II), Streptococcus mutans, Bacteroides intermedius, Eubacterium brachy, and Eubacterium alactolyticum in the SF from the normal and irreversible pulpitis tissues were observed with a large variation of antibody levels in both groups. Immunodiffusion assays of the SF revealed that IgG was the major class of immunoglobulin in the normal as well as the irreversible groups. The presence of natural antibodies in the normal pulps suggested a possible protective role of antibodies during the invasive process of caries.
Article
The fraction of the volume of the coronal pulp of cat canines that is occupied by blood vessels was estimated by measurement of the cross-sectional areas of all the vessels in a complete transverse section of the pulp from each of four teeth. The sections were taken 0.5 mm from the pulp comu. Overall, 14.4% of the area of the pulp was occupied by vessels. In the core of the pulp, the average value was 42.9%, and superficially, near the odontoblast layer, it was between 5 and 10%. The average capillary density was 1402 /mm ² , which is higher than in most other tissues. Laser Doppler flow meters can be used for recording blood flow from the coronal pulp of intact teeth, but these instruments are linear only if the moving blood cells occupy no more than 1% of the tissue volume. The present results suggest that this figure is exceeded in pulp.
Article
Previous studies of the sympathetic nerve supply of the rat mandibular incisor pulp have shown conflicting results. Here, the neurovascular control of the rat lower incisor pulp was investigated by stimulating the tooth crown and the cervical sympathetic trunk electrically and monitoring blood-flow changes in the pulp by laser Doppler flowmetry. In addition the presence of noradrenaline (NA) in the pulp and gingiva was examined biochemically in untreated and sympathectomized animals by high-performance liquid chromatography. The tissue concentrations of NA in the pulp were 11-fold greater than those of gingiva. Surgical sympathectomy significantly reduced the NA content in the pulp by 76%. Monopolar electrical stimulation of teeth (25-50 microA) for 1 min resulted in a frequency-dependent reduction followed by an increase in pulpal blood flow. At 16 Hz the reduction in blood flow was 65% and the subsequent increase was 9%. After intravenous administration of the alpha-adrenoceptor antagonist phentolamine, the stimulation-induced reduction in pulpal blood flow was diminished by 94% while the increase was significantly enhanced (from 9 to 40%). Infusion of the beta-adrenoceptor antagonists propranolol and timolol significantly reduced this increase in blood flow by 53 and 55%, respectively. Preganglionic sympathetic nerve stimulation also induced a frequency-dependent reduction followed by a slight increase in pulpal blood flow. This reduction in blood flow was almost abolished after alpha-adrenergic blockade and there was no subsequent increase. These findings suggest that there are sympathetic nerve fibres in rat incisor pulp and that they are activated upon monopolar electrical stimulation of teeth resulting in alpha- and beta-adrenoceptor mediated blood-flow responses.
Article
In 15 subjects, laser-Doppler flowmetry (LDF) was used to investigate whether the nervous control of pulpal blood flow (PBF) is affected by three tests known to excite the sympathetic nervous system. For comparison, skin blood flow was similarly recorded. Dynamic exercise (bicycle ergometer, 5 min, 90-100 W) in eight subjects was accompanied by a rise in PBF. PBF was increased by the cold pressor test (2 min) in eight subjects, while in five the flow decreased or remained unaffected. The isometric hand grip (2 min, 30% MVC) and the subsequent muscle ischaemia (2 min) led to a rise in PBF in two subjects and a fall in four. Following unilateral anesthesia of the mandibular nerve, PBF in five subjects became unresponsive to dynamic exercise or the cold pressor test, indicating pressure autoregulation. All three tests triggered increases in mean arterial pressure (MAP) and heart rate (HR). Skin blood flow usually increased in response to the tests, but could also decrease, and often changed in a direction opposite to that of PBF. It is concluded that the circulation of blood in the human tooth is affected by evoked changes in autonomic nerve activity, involving activation of both vasodilator and vasoconstrictor nerves to vessels serving the tooth.
Article
The existence of commensal or antagonistic relationships between microorganisms in the root canals of teeth with apical periodontitis was investigated. Samples were taken from 65 infected human root canals and were analysed according to species, frequency of occurrence and proportion of the total isolated flora. The most frequent species were Fusobacterium nucleatum, Prevotella intermedia, Peptostreptococcus micros, Peptostreptococcus anaerobius, Eubacterium alactolyticum, Eubacterium lentum and Wolinella recta. An odds ratio system was used to calculate positive or negative associations between the isolated bacteria. Strong positive associations were found between F. nucleatum and P. micros, Porphyromonas endodontalis, Selenomonas sputigena and W. recta. There was also a positive association between P. intermedia and P. micros, P. anaerobius and the eubacteria. In general, species of streptococci, Propionibacterium propionica, Capnocytophaga ochracea and Veillonella parvula showed no or negative associations with the other bacteria. The results are consistent with the concept of a special and selective environment occurring in the root canal that is due, in part, to the cooperative as well as antagonistic nature of the relationships between bacteria in the root canal.
Article
The reactions of sensory nerves to restorative procedures can be classified as immediate, early and late. For each of these, the neural response depends upon the severity of pulpal injury and the stages of inflammation and healing. Immediate responses in the first few minutes include destruction of nerve fibers in the injured dentin and pulp, hypersensitivity of surviving fibers, release of neuropeptides into the pulp and neurogenic inflammation. Early responses occur during the first few days after cavity preparation, with nerve fibers sprouting in the surviving pulp and gaining increased axonal transport and neuropeptide contents. Sensory fibers containing calcitonin gene related peptide (CGRP) greatly outnumber those with substance P (SP); but both types grow toward the surviving odontoblasts and associated pulp tissue surrounding the lesion. Later during subsequent weeks the nerve fibers accompany granulation tissue as it replaces acute inflammation; and nerve sprouting subsides when inflammation is reduced and when reparative dentin covers the injury site. An important response to tooth injury that may regulate nerve sprouting reactions is the increased production of nerve growth factor (NGF) by pulpal fibroblasts near the lesion. The timing of the nerve sprouting reactions suggests that they may contribute to tooth hypersensitivity after restorative procedures.
Article
Using the quantitative 15 microns microsphere injection method, the effects of several restorative procedures on pulpal microcirculation in dog canine teeth were investigated. Pulpal blood flow (PBF) decreased steadily as the remaining dentin thickness (RD) became smaller with crown preparation without water spray. One hour after the preparation wit 1/3 RD (approximately 1 mm) PBF was reduced to 10% of the control, indicating that dry deep preparation has a deleterious effect on PBF. A careful preparation to an RD of 1 mm under copious water spray had a negligible effect on PBF. Dry preparation to an RD of more than 50%, on the other hand, caused a significant increase in blood flow through shunt vessels, AVAs and "U"-turn loops as determined with the 9 microns and 15 microns microspheres. These shunt vessel activities were especially prominent in the apical portion of the pulp, suggesting that the activation of the shunt vessels may be one of the compensatory mechanisms of the pulp in response to inflammation. In rat incisor teeth observed by intravital microscope, shunt vessels opened up as the incisor tips were drilled. Impression procedures after tooth preparation with water spray using the copper band with wax caused severe flow fluctuation as compared to rubber base material impression. In anesthetics, the use of epinephrine was found to be the single most important factor affecting pulp circulation. Whether it is by infiltration or mandibular block, the use of epinephrine containing anesthetic caused a severe reduction in PBF.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
During dental treatment temperatures can be reached which might possibly damage the tooth pulp. To determine the effect of both thermal stimulation on pulpal microcirculation and local anesthesia on thermoregulation we measured the pulpal blood flow by using laser Doppler flowmetry. Experiments were carried out on lower incisors of Wistar rats anaesthetized with thiopental. The rats were divided into three groups, with one remaining untreated, and the others being either desensitized with capsaicin or sympathectomized with guanethidine. In a range between 33 degrees C and 42 degrees C there was no substantial change in blood flow, which, however, was the case below 33 degrees C. Up to 49 degrees C an increase could be recorded in both untreated and guanethidine pretreated animals, whereas the capsaicin groups showed almost no reaction. This increase in blood flow can be blocked reversibly by local anaesthesia. For this purpose we tested articain 5% and mepivacain 3%, both without constrictor. Intravital microscopic studies show that the temperature related increase in blood flow is also associated with plasma extravasation. From these results we draw the conclusion that pulpal thermoregulation is linked to nociceptive sensory neurons and can be described as "neurogenic inflammation".
Article
Small diameter afferent nerves in the pulp contain vasoactive peptides (tachykinins and CGRP) which are released upon nerve stimulation causing long lasting vasodilation. The aim of the present experiments was to study the contribution of afferent nerves in vasodilator reactions in the cat dental pulp when clinical procedures were applied. For this purpose the inferior alveolar nerve (IAN) was cut unilaterally 10 days prior to study. Lower canines were then subjected to various stimuli and blood flow responses in the pulp were monitored by laser Doppler flowmetry. Bipolar electrical tooth stimulation (5 impulses, at 2 Hz, 50 microA) and application of capsaicin (10(-4) M) in a deep cavity instantaneously induced long lasting increases in pulpal blood flow in control teeth but not in denervated teeth. Bradykinin (10(-3) M) applied locally produced a more rapid and larger pulpal vasodilation in innervated than in denervated teeth. Intermittent grinding (3 times, 1 sec each) of surface dentin with a round diamond bur instantly increased flow in control teeth by 53%, whereas in denervated teeth the response was delayed and significantly smaller (16% increase). Deeper preparations produced long lasting responses of similar magnitude on both sides but the onset was much slower in denervated teeth. Percussion and low intensity ultrasonic stimulation (1 sec) instantly caused increased flow in control teeth but not in denervated teeth. The effect was abolished by local anesthetic (mepivacaine) injection apically. Sympathectomy and acute IAN denervation did not alter the responses. The results show that afferent (sensory) nerves contribute importantly to hemodynamic reactions in the pulp in response to clinical procedures.
Article
The initial vascular reactions during inflammation are vasodilation and increased vessel permeability. Both these basic reactions cause increased pulpal fluid volume. In the dental pulp the inflammatory vascular reactions take place in a rigid enclosed dentin chamber, which to some extent makes the pulp vulnerable. Due to this lack of distensibility any gain in pulpal volume will necessarily increase the pulpal tissue pressure. If the tissue pressure rises to the same level as the blood pressure it will compress the pulpal vessels, thus counteracting a beneficial blood flow increase during inflammation. Using the micropuncture technique and laser Doppler flowmetry we have performed simultaneous measurements of tissue pressure and blood flow in the cat dental pulp during neurogenic inflammation. Sensory nerve stimulation caused a rise both in blood flow and tissue pressure. Our findings thus strongly suggest that the increased pulpal tissue pressure promote fluid absorption back into the blood. If, in theory, plasma proteins and other macromolecules had leaked out during sensory nerve stimulation they must have been successfully removed by lymphatics, unless the tissue pressure would have risen to the same level as the capillary blood pressure causing a fall in PBF. This was not found. On the contrary, increased blood flow was measured, even in experiments lasting for more than 8 hours. It is therefore concluded that the pulp may have a beneficial blood flow increase during inflammation in spite of simultaneously increased tissue pressure.
Article
This communication focuses on the participation of accessory cells in the initial recognition and processing of antigenic substances in the dental pulp. Immunohistochemical analyses have demonstrated the presence of two types of accessory cells--one with a dendritic morphology located in the periphery of the pulp and one with a macrophage-like appearance located more centrally. Functional studies in vitro have provided evidence for the dendritic cells being the most significant of the two cells regarding their capacity to induce T-cell proliferation. Studies on ontogeny have revealed that the appearance of pulp accessory cells is delayed compared to other peripheral tissues. In experimentally induced pulp lesions a rapid increase of cells with morphologic and phenotypic features similar to normally occurring accessory cells was found. These data demonstrate that the dental pulp contains the necessary cellular constituents to mount an immunologic defense reaction. Future studies should focus on elucidating possible interactions between these immune cells and the neurovascular system of the pulp.
Article
Sickle-cell disease is characterized by the pathophysiological features of chronic hemolytic anemia, vaso-occlusion resulting in ischemic tissue injury and painful episodes. The organs at greatest risk are the spleen, kidney and bone marrow, where oxygen tension is low and blood flow is diminished. However, disease may also present in the mandible. The oral manifestations and radiographic findings of a sickle cell patient with a left mandibular neuropathy, along with dental management guidelines are presented in the context of interdisciplinary care.
Article
An outward flow of fluid through exposed dentine was demonstrated in anaesthetized cats. The flow was measured by observing the movement of the fat droplets of dilute milk in a glass capillary (i.d. 30 microns) with a microscope. The capillary was sealed to the dentine with a plastic cap. The resting flow rate through dentine exposed by fracturing off the tip of a cat's canine ranged from 2.8 to 50.9 pl.s-1.mm-2 (mean 18.1, SD 15.9, n = 12). Raising the pressure at the dentine surface to about 15 cmH2O stopped the flow. Immediately after cutting the pulp at the root apex, in 11 of 12 preparations, the flow reversed. The average flow rate was then 3.8 pl.s-1.mm-2 inward (range 8.4 outward to 15.9 inward, SD 5.4, n = 12). The inward flow after pulp section suggests that an osmotic effect may contribute to the net pressure causing flow. The average hydraulic conductance of the exposed dentine was 1.6 x 10(-8) m.s-1.kPa-1 (range 0.5-2.9, SD 0.8) before pulp section. After pulp section, it increased to an average of 2.5 x 10(-8) m.s-1.kPa-1 (range 0.8-5.2, SD 1.3).
Article
The apparent impermeability of dentinal tubules to chemicals applied to exposed dentine in vivo was investigated. It was shown that whereas Evans' blue diffused readily into dentine in extracted teeth, it did not do so in visible amounts when it was applied in vivo. In the in vitro experiments, decreasing the pressure of the Evans' blue solution to 20 cmH2O below atmospheric apparently prevented the dye entering the tubules, while increasing the pressure of the solution to 15 cmH2O or more above atmospheric in vivo resulted in the dye penetrating the dentine in high concentrations. It is concluded that, in cat dentine in vivo, there is an outward flow of fluid through exposed dentinal tubules, and that this flow is sufficient to substantially reduce diffusion into the tubules of chemicals such as Evans' blue.
Article
Oral microorganisms, either directly or indirectly, produce the majority of cases of pulpal and periapical disease. Because microorganisms play such an important role in the pathogenesis of pulpal and periapical disease, a fundamental understanding of the disease process is important. Culture studies have identified infections of endodontic origin as being polymicrobial and predominantly anaerobic. Although several species of bacteria have been associated with infections of endodontic origin, there is no absolute correlation with signs and symptoms. The use of immunologic studies in addition to traditional microbiologic studies provides a better understanding of the mechanisms involved in the pathogenesis of pulpal and periapical disease.
Article
The two key components in pulpal inflammation are microcirculation and sensory nerve activity. With advancement of techniques they can be measured simultaneously in the same tooth. Excitation of A-delta fibers seems to have an insignificant effect on pulpal blood flow (PBF), whereas C fiber activation causes an increase in PBF. This C fiber-induced PBF increase is caused by neurokinins, especially substance P, which is released from the C fiber nerve terminals. Manipulation of PBF has varying effects on sensory nerve activity. An increase in PBF causes excitation of both A-delta and C fibers via an increase in tissue pressure, whereas flow reduction has an inhibitory effect on A-delta fibers, but no discernible effect on C fiber activity. Understanding of this complex neurovascular relationship in the pulp, especially given the fact that the pulp is in a low compliance system, is prerequisite to more comprehensive characterization of pulpal inflammation.
Article
The potential danger of low oxygen tension to patients with sickle cell disease is widely known. However, less well known is the phenomenon of patients with sickle cell disease presenting with toothache in the absence of any dental pathology. This study investigated the experience of orofacial pain in three matched groups, comprising patients with sickle cell disease, sickle cell trait and patients with no known blood dyscrasia. There were no differences in pain experience between those groups with sickle cell trait and no known blood dyscrasia. The sickle cell disease patients experienced significantly more orofacial pain in the same 12-month period than the other groups. The pain was also more frequent and of longer duration. In two-thirds of those sickle cell disease patients who experienced toothache, no dental pathology was found, in direct contrast to patients with trait or no known blood dyscrasia. Sickling of blood cells within the dental pulp in a sickle cell crisis may result in pain within teeth. These patients may then present as experiencing toothache in the absence of any dental pathology. General dental practitioners should be aware of this phenomenon when providing care for these susceptible patients.
Article
Substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactivity (-IR) were localized by immunohistochemistry in the same nerve cell bodies in the trigeminal ganglia as well as in nerve terminals of the dental pulp. The distribution of SP- and CGRP-IR nerves were identical in the dental pulp and mainly associated with blood vessels. The level of CGRP-IR in the dental pulp, as measured by radio-immunoassay (RIA), was 1.4 +/- 0.2 pmol g-1 wet wt, which is in the same range as that found for substance P. Local intra-arterial infusion of synthetic CGRP and substance P produced vasodilatation in the dental pulp as measured by both laser Doppler flowmetry and an 125I clearance technique. The CGRP was effective as a vasodilator when infused in the femtomole per minute range, and SP in the picomole range. The effect of CGRP (50 fmol min-1) was 10 times larger when given after SP (15 pmol min-1) than before it. Since the two peptides coexist in the same neurons, it is suggested that they both contribute to the vasodilation seen upon antidromic stimulation of sensory nerves.