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Identifying and Reducing Risks for Potential Fractures in Endodontically Treated Teeth
Abstract
Although long-term functional survival rates can be high for initial endodontically treated permanent teeth, they are generally more susceptible to fracture than teeth with vital pulps. Tooth extraction is often the consequence of an unfavorable prognosis after coronal and root fractures, but their occurrence in endodontically treated teeth might be reduced by identifying the risks for fracture associated with various operative procedures.
This article presents an overview of the risk factors for potential tooth fractures in endodontically treated teeth on the basis of literature retrieved from PubMed and selected journal searches.
Postendodontic tooth fractures might occur because of the loss of tooth structure and induced stresses caused by endodontic and restorative procedures such as access cavity preparation, instrumentation and irrigation of the root canal, obturation of the instrumented root canal, post-space preparation, post selection, and coronal restoration and from inappropriate selection of tooth abutments for prostheses.
Potential tooth fractures might be reduced by practitioners being aware during dental treatments of controllable and noncontrollable risks.
... Multiple studies, over several years, have explored most of these factors with impactful contributions to the field, which has helped in the current trends of evidence-based dental practices. However, with new clinical protocols and innovations in dental materials there are new associated challenges, which require continuous research studies to provide an adequate scientific basis for offering solutions and enhancing the durability of the restored tooth [8][9][10]. ...
... There is evidence that vital teeth are less susceptible to fractures than endodontically treated ones [6][7][8][9][10][11]. In the latter, changes in the chemical and physical properties of dentin after endodontic treatment [12][13][14] would result in crack formation and a weaking of the dental tissue that is now more prone tooth fracture [9,[14][15][16]. ...
... There is evidence that vital teeth are less susceptible to fractures than endodontically treated ones [6][7][8][9][10][11]. In the latter, changes in the chemical and physical properties of dentin after endodontic treatment [12][13][14] would result in crack formation and a weaking of the dental tissue that is now more prone tooth fracture [9,[14][15][16]. ...
Irrigating solutions play an important role in the eradication of intracanal microbes and debris dissolution during endodontic treatment. Different combinations of solutions and protocols have been advocated, with sodium hypochlorite (NaOCl), ethylenediamine tetra acetic acid (EDTA), and chlorhexidine (CHX) remaining the most widely used ones by many clinicians. Although these solutions provide efficient inorganic dissolution and antimicrobial capacity, their use has also been reported to cause undesired effects on root dentin composition and mechanical and biomechanical properties, such as microhardness, surface roughness, bond strength, and matrix metalloproteinase (MMP) activity. Several corroborating studies attribute these changes in mechanical properties of dentine to the use of irrigating solutions, and there are limited reports on how the solutions affect the expression of MMPs, which may be a correlating link to understanding the role of these enzymes in dentin collagen and changes in the mechanical properties of dentin. Hence, using the basis of several studies from the literature, the objective is to comprehensively review the influence of individual and combined irrigating solutions on root dentine structure and the activity of the MMPs.
... When the prime is unable to reach operating length in severely curved canals easily or when it is challenging to prepare the glide path, the yellow stopper small file is employed that confines to the "ISO 20 tip size and a 0.04 taper." [37][38][39] clInIcAl guIdelInes A n d Instrument desIgn ...
... "Orifice Modifier" is advised for use in all canal systems, regardless of the preparation. [34][35][36][37][38][39] ...
... Some authors suggest that cracked teeth, requiring endodontic treatment, will present a worse prognosis in long time [32,33]. This is predictable since there is loss of internal structure, due to the need for direct access along the canal. ...
... Therefore, it is believed that the importance of performing a treatment with onlays, in which the cusps are covered, or the use of a full crown despite doubtful prognosis is indisputable [16,17]. The preparation and placement of temporary crowns in acrylic resin or direct restoration with photo-activated composite resins with cusp coverage (Cases 1, 2, and 3) has been described as a predictable option of immediate splinting for CTS [33,35]. IMTRs are considered a necessary step, but only for short time, so as to assess whether or not the symptoms will subside. ...
Different restorative techniques have been proposed for the treatment of posterior teeth affected by cracked tooth syndrome (CTS). However, the literature is scarce in protocols of how to solve CTS using ceramic restorations made by computer aided design-computer aided manufacturing (CAD-CAM) system. CAD-CAM provides a fast and efficient restorative treatment usually in a single visit, reducing the risk of contamination and micro-infiltration of the cracked line. The objective of this work was to describe 3 clinical cases of cracked teeth, which presented vertical fracture lines in different directions and extension through the pulp, restored by CAD-CAM system, with 5-year follow-up. Patients with short-term spontaneous masticatory pain, cold sensibility and restored teeth without cuspal coverage were selected. Digital radiographs (DR) were taken to confirm the pulp and periapical status. Periodontal probing depth, sensitivity, percussion, and occlusion tests were performed. The fracture lines with their direction and extension were identified under dental optical microscope (DOM). The treatment plan was performed in two stages: immediate treatment to stabilize the tooth and minimize pain, and final restorative treatment by CAD-CAM system to stabilize the crack. Patients were between the ages of 37 and 45 years. Most of the studied teeth presented extensive restorations without cuspal coverage. The presence of occlusal interference, in lateral movement, was a constant finding. Endodontic treatment was performed in cases of irreversible pulpitis or pulpal necrosis. In all three cases, cavity preparation was performed for full coverage restorations, as the fracture lines extended in several directions, requiring a re-enforcement of the cervical region of the teeth in question. The survival rate of the reported cases was 100% with 5-year clinical and radiographic follow-up, suggesting that CAD-CAM system may be a promising alternative treatment in the management of CTS, improving tooth longevity.
... The present authors formed three experimental groups composed of teeth with different thicknesses. The selection considered the influence of dentine thickness in the development of VRF 21 and the knowledge that VRF is more prevalent in teeth with a reduced dental structure, such as mandibular molars and maxillary premolars [22][23][24] , often with endodontic treatment 25 and/ or with intraradicular retainers 26,27 . The remaining tooth thickness may vary according to the type of teeth, the endodontic instrumentation technique (manual, rotary, etc.) 25,28 and the type of preparation made to receive an intraradicular retainer 29 . ...
... The selection considered the influence of dentine thickness in the development of VRF 21 and the knowledge that VRF is more prevalent in teeth with a reduced dental structure, such as mandibular molars and maxillary premolars [22][23][24] , often with endodontic treatment 25 and/ or with intraradicular retainers 26,27 . The remaining tooth thickness may vary according to the type of teeth, the endodontic instrumentation technique (manual, rotary, etc.) 25,28 and the type of preparation made to receive an intraradicular retainer 29 . In this respect, reduced dental structure is associated with greater susceptibility to VRF 30 and greater radiographic sharpness. ...
Objective:
To undertake a joint analysis of the influence of fracture width, dental thickness and distance of the fracture from the cortical bone on the radiographic diagnosis of vertical root fractures.
Methods:
Thirty-six uniradicular bovine teeth were endodontically treated and distributed into three groups according to the remaining root dentine thickness: 1.2 mm, 1.5 mm and 1.8 mm. Each group comprised 12 teeth, six with vertical root fracture and six without. Scanning electron microscopy (SEM) images of the fractured tooth groups were obtained and the fracture lines were measured. All specimens were inserted into bone defects created in bovine ribs, at different distances from the external cortical bone. Digital periapical radiographs were randomly evaluated by three blinded examiners (presence or absence of fractures).
Results:
The specificity for periapical radiography was found to be 89% and the accuracy rate was 57.4%. The mixed-model regression using the generalised estimating equation (GEE) model showed that the width of the fracture line and the thickness of the dental remnant play an important role in radiographic detection of vertical root fractures. There is a lower chance of correct diagnosis with fracture line widths < 0.2 mm (odds ratio [OR] 0.294, 95% confidence interval [CI] 0.103 to 0.836; P = 0.022) and tooth thicknesses < 1.2 mm (OR 0.342, 95% CI 0.157 to 0.747; P = 0.007).
Conclusion:
Fracture line widths < 0.2 mm and smaller root thicknesses lead to a less accurate diagnosis of vertical root fractures on periapical radiographs.
... It has always been challenging to obturate the oval-shaped root canals compared to the root canals with a round crosssection (Ozawa et al., 2009). In recent years, especially with the understanding of the importance of irrigation and the effective use of irrigation activation systems, minimally invasive instrumentation has been recommended in endodontic treatment with the philosophy of improving resistance to tooth fracture by preserving the structural integrity of peri-cervical dentin (Tang et al., 2010). Therefore, the present study was conducted in oval-shaped root canals, which were instrumented with low-tapered Ni-Ti files. ...
... This was significantly different from 87.4% of undergraduate students who "sometimes" or "often" or "always" practiced preparing larger apical sizes to reduce the bacterial load inside the canal. Studies have shown that minimal sizes can accomplish this task of elimination of bacteria as adequately as larger diameters [82][83][84]. ...
Background: The philosophy of minimum interventional dentistry (MID) is to integrate prevention, remineralization, and minimal intervention for the placement and replacement of restorations. All branches of dentistry play an important role in practicing MID, and their primary goal is to realize that any restoration is of less biological significance than the healthy original tissue Objectives: The objective of this study was to assess the perception of MID among dental undergraduate students and interns in terms of knowledge, attitude, and practice at the College of Dentistry. Materials and Methods: This cross-sectional study was conducted among undergraduate students and interns at the College of Dentistry, Qassim University, Saudi Arabia. A self-administered questionnaire was distributed, which included basic demographic profiles and questions about the knowledge, attitude, and practices toward MID. The data were tabulated in MS Excel, and all statistical analyses were performed using SPSS version 21. Results: A total of 163 dental students were recruited, with senior students comprising 73% and interns comprising 27%. Male students were slightly more prevalent (50.9%) than female students (49.1%). About 37.6% of participants received training about MID during educational courses, while 10.3% received it during their internship. A statistical test revealed that the prevalence of interns who were trained in performing MID was significantly higher (p < 0.001). Conclusions: The majority of the participants demonstrated proper knowledge, attitude, and practice in different aspects of MID. Interns reported a higher rate of knowledge, attitude, and practice in MID compared to undergraduate students. However, more education and hands-on training about MID concepts during the college curriculum are necessary to attain better knowledge, attitude, and practices that could be useful for more conservative clinical practice.
... The vertical stresses created in preparing and seating vertical posts can lead to root fracture. 20,21 Post space preparation for a vertical post may, by removing dentin in the critical cervical area of the tooth, weaken the tooth even further and subject it to horizontal fracture along with strip perforation in the furcal area. 22 The placement of a horizontal post may provide a short-term benefit in increasing fracture resistance for the patients who cannot afford the immediate cost of a full coverage restoration after root canal therapy. ...
Current literature suggests that tooth fracture post endodontic treatment is a more common complication than an endodontic reinfection. The best way to treat such complication is rehabilitation with complete coverage restoration with or without a foundation restoration. Critical analysis of several in vitro studies suggest that a posterior glass fiber reinforced composite restoration, particularly with glass fiber posts placed horizontally in a bucco-lingual direction improves the fracture resistance significantly. These case reports describe in detail the method of placement of posts horizontally rather than the conventional vertical placement in endodontically treated teeth to strengthen the remaining coronal tooth structure.
... When evaluating longevity and retention of endodontically treated teeth, fracture and subsequent loss after endodontic treatment remains a major concern 1, 2 . Preserving structural integrity, and specifically pericervical dentin is a key factor influencing fracture resistance and longevity of these teeth 3,4 . Access cavity preparation and canal instrumentation are therefore aimed at preserving tooth structure as much as possible without compromising visibility and access. ...
... Cuspal coverage of posterior endodontically treated teeth is recommended to minimize tooth fracture and restore function [1][2][3]. However, the choice of appropriate restorative treatment modality in these situations is not simply reached. ...
This in vitro study aimed to evaluate the fracture resistance and mode of failure of en-docrowns with proximal extension design compared to the conventional design, and to assess the agreement of evaluators on the failure mode. Twenty mandibular third molars free of caries with approximately similar root lengths and crown dimensions were sectioned parallel to the occlusal plane 2 mm above the cementoenamel junction (CEJ). Then, pulp chambers and canals were accessed, cleaned, and smoothed for the path of insertion. To achieve a symmetrical pulp chamber with an average depth of 3 mm, chambers were filled with flowable resin composite. Then, teeth were randomly divided into two groups (n = 10). The control group has all the walls at the same level. The test group had a box extension on the proximal wall 2 mm apical to the buccal and lingual wall level. Endocrowns (n = 20) of two different designs (conventional and proximal extensions) were fabricated using lithium disilicate (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein). After cementation, specimens were loaded with a round-end vertical loading tip at a rate of 0.5 mm per minute until fracture (INSTRON, Norwood, MA, USA). Then, the fractured specimens were collected for evaluation and assessment. Statistical analyses were performed using the Mann-Whitney U-test (α = 0.05) for fracture test analysis and Cohen's Kappa for inter-rater reliability. The Mann-Whitney U-test showed a non-significant difference between the two groups (p = 0.142). However, the mode of failure of the endocrown with proximal extension showed more catastrophic failures than the conventional design. Adding proximal boxes to the endocrown design did not negatively impact the fracture resistance of the restoration. Visualization of the fracture line and tracing their apical end by direct vision or other diagnostic tools is an essential part of the evaluation of failures of endocrowns. Endodontically treated molar teeth with proximal caries extension might be restored with an endocrown with proximal extension. Clinicians should take extra care when visualizing the fracture lines and tracing their apical end as it might be very misleading.
... Compared with vital teeth, root canal treated roots have a higher risk of fracture [1]. Endodontic treatment procedures such as access cavity, root canal preparation, irrigation and obturation, may result in weakened dentinal walls and predispose roots to vertical fracture [2,3]. Applying mechanical forces during root canal instrumentation may increase strain and possibly create microcracks at the root surface [4,5]. ...
Background: This study aimed to develop a mathematically valid method of assessing fracture resistance of roots. The model developed used mesial roots of lower molars instrumented using stainless steel hand files (SS) and two rotary nickel-titanium (NiTi) systems.
Methods: Eighty human lower molars were selected and randomly divided into four groups (n=20). After instrumentation, the root canals were obturated using thermoplasticized gutta percha. The roots were covered with a simulated periodontal ligament and mounted vertically in autopolymerizing acrylic in PVC tubes. Using a universal testing machine, the force to fracture (N) was applied and the maximum load (FL) was recorded. Remaining dentin volume was calculated and the fracture resistance (FR) was recorded. The data were analyzed using SPSS version 22 with P < .05.
Results: There were no significant differences among the instrumentation methods for FL but in FR the roots instrumented using rotary NiTi showed significantly lower values than control groups and SS files (P <0.001).
Conclusions: Considering the effect of root length, volume of the root, and volume of the instrumented canal as well as the maximum failure load may be a more objective method of reporting fracture resistance of roots.
... The shaping, cleaning, and disinfection would allow for a three-dimensional obturation (3D) of the root canal system from a biomechanical standpoint [2]. Extreme tooth structure loss due to trauma or caries, access cavity preparation and design, dryness of dentin, instrumentation with rotary files, excessive pressure during filling procedures, detrimental effects of irrigation solutions, and preparation for intra-radicular post space are all factors that affect the strength of root canal treated teeth and has been shown in studies to increase root fracture susceptibility [3][4][5][6][7]. In terms of clinical outcomes, these fractures may result in a poor prognosis of endodontic treatment and lower the long-term survival rate of the tooth. ...
Aim:
To compare the effect of different tapers of the K3XF file system on the fracture resistance of endodontically treated mandibular premolars obturated with a three-dimensional (3-D) obturation system.
Methodology:
For the study, 80 freshly extracted human mandibular premolars with single well-developed roots without any curvatures were taken and the tooth roots were wrapped in a single layer of aluminum foil, and they were placed vertically in a plastic mold filled with self-curing acrylic resin. The access was opened, and working lengths were determined. The canals were instrumented keeping an apical size of #30 by different taper rotary files: Group 1: un-instrumented (control group), Group 2: 30/.04, Group 3: 30/.06, Group 4: 30/.08 K3XF file system, and teeth were obturated using a 3-D obturation system, and access cavities were filled using composite. Both experimental and control groups were subjected to fracture load using a conical steel tip (0.5mm) attached to a universal testing machine to record force applied in newton until root fracture.
Results:
Root canal instrumented groups showed lower fracture resistance than the uninstrumented group.
Conclusion:
Hence it could be concluded that endodontic instrumentation with increased taper rotary instruments caused a decrease in fracture resistance of the teeth, and biomechanical preparation of root canal system with rotary or reciprocating instruments caused a significant decrease in fracture resistance of endodontically treated teeth (ETT), thereby decreasing their prognosis and long-term survival.
... Another in vitro study hypothesized that the tooth type significantly increased the chances of a tooth fracture after root canal instrumentation 57 . Complete instrumentation of root canals with excessive removal of dentin, presence of irregular shaped canals and poor gutta-percha condensation increased the risk of root fracture [58][59][60] . The risk factors for the fracture of an endodontically treated tooth could be: (1) chemical: as result of endodontic irrigating solutions or dentinal medications 54 , (2) microbial: caused by bacteria-dentine interaction 6 , (3) dentinal: due to tooth structure loss, (4) restorative: ...
A Comparative Evaluation of Root Fracture Resistance of Endodontically Treated Teeth using Two Fiber Posts with Two Ferrule Heights
... The predisposing factors are actually uncontrollable. These are biochemical changes in the dentin at the root of root canal treated teeth, pre-existing cracks in untreated teeth, and the specific anatomy of vulnerable teeth with VRF (Tang et al., 2010). Contributing factors have been attributed to iatrogenic risk factors associated with various dental procedures performed on the teeth (Reeh et al., 1989). ...
Highlights Vertical root fracture is a complete or incomplete fracture initiated from the root mostly or can also initiate at any level above the CEJ. The signs, symptoms, and radiographic findings of VRF can be confused with those of advanced peri-odontal disease or endodontic treatment failure, thus complicating the diagnosis. Vertical root fractures have been reported to occur primarily in endodontically treated teeth due to compaction forces and/or with post placement. Vertical root fracture is one of the most frustrating conditions in dental office. In most cases, it leads to extraction-or at least root amputation. The aim of the present study was to assess the knowledge of Libyan dentists about vertical root fractures (VRF), causes, clinical signs and symptoms, diagnosis and treatment and to find out the relationship between the knowledge and sociodemographic data of the dentists. Materials and Methods: This was a descriptive cross-sectional study. The survey was carried out in Benghazi (Libya) in 2021. 375 dentists were invited. Data were collected using an electronic questionnaire. The questionnaire is designed to consist of two parts; the first part deals with the demographic characteristics of the participants and the second part is divided into four aspects to assess the knowledge of participants about VRF; (the definition and general information of VRF, the signs, symptoms, and diagnostic process of VRF, factors that contribute to VRFs and the preferred treatment of VRF in single-root and multi-rooted teeth). The survey data were statistically analyzed using Fisher's Exact test. Results: The survey response rate was 375/225(60%). Almost half of respondents 112 (49.8%) had moderate Knowledge score about (definition and general information of VRF) and (the signs, symptoms and diagnostic process of VRF). The relationship between the knowledge score of the Libyan dentists regarding the signs, symptoms and diagnostic process of VRF and (gender, Specialization) was statistically significant difference p value < 0.05. The male participants in this study had higher knowledge score than female regarding this section. The endodontists had a higher knowledge for diagnosis of VRF than others did. More than half (63.1%) and Almost half (46.2%) of respondents had high knowledge scores about contributing factors to the susceptibility of root to fracture and the preferred treatment for VRF in single and multi-rooted teeth, respectively. The relationship between the knowledge score of the Libyan Dentists regarding the preferred treatment for VRF in single and multi-rooted teeth and gender was a statistically significant difference p value <0.05. The male participants in this study had higher knowledge score than female participants regarding the preferred treatment for VRF. Conclusion: This study showed that around half of the participants had moderate to high knowledge regarding to different aspects of VRF.
... The endodontic treatment goal is to maintain natural tooth structure as much as possible. 1,2 Shaping root canals is one of the most important steps in root canal treatment. It is critical for proper treatment of root canal as it affects all following procedures, including chemical disinfection and filling of the root canal. ...
... However, these treatment procedures remove the pulp and some dentin tissues, which weaken the dentinal strength, immunological responses and proprioceptive functions, leading to a higher risk of reinfection and tooth fracture. 3,4 How to reconstruct vital pulp and restore the biological function of teeth becomes the goal of contemporary endodontics. ...
Regenerative endodontic procedures (REPs) is a biologic-based treatment modality for immature permanent teeth diagnosed with pulp necrosis. The ultimate objective of REPs is to regenerate the pulp-dentin complex, extend the tooth longevity and restore the normal function. Scientific evidence has demonstrated the efficacy of REPs in promotion of root development through case reports, case series, cohort studies, and randomized controlled studies. However, variations in clinical protocols for REPs exist due to the empirical nature of the original protocols and rapid advancements in the research field of regenerative endodontics. The heterogeneity in protocols may cause confusion among dental practitioners, thus guidelines and considerations of REPs should be explicated. This expert consensus mainly discusses the biological foundation, the available clinical protocols and current status of REPs in treating immature teeth with pulp necrosis, as well as the main complications of this treatment, aiming at refining the clinical management of REPs in accordance with the progress of basic researches and clinical studies, suggesting REPs may become a more consistently evidence-based option in dental treatment.
... A pulpotomy may substantially decrease the loss of tooth structure and the induced www.nature.com/scientificreports/ stresses caused by endodontic procedures, which would make the post-endodontically treated tooth more vulnerable to irreparable fracture 25 . Without the need for complex endodontic procedures, a pulpotomy is a more time-efficient and operator-friendly treatment. ...
This study aimed to investigate the factors affecting the success rate of full pulpotomy in permanent posterior teeth with pulpitis. The study included 105 permanent posterior teeth clinically diagnosed as reversible or irreversible pulpitis in 92 patients aged 18–82 years. All teeth underwent a full pulpotomy using mineral trioxide aggregate as a capping material and were recalled for clinical and radiographic evaluation at 3, 6, 12, and 24 months postoperatively. The overall success rate after the 12-month review was above 90%, and failed cases mainly occurred during the first 12 months after treatment. In this study, the treatment outcome of pulpotomy was not related to sex, or tooth position and the cause of pulpitis. To analyze the influence of age on the treatment outcome, all the teeth were allocated to three groups: group 1 (18–39 years); group 2 (40–59 years); and group 3 (≥ 60 years). A significant difference in success rate was found between groups 1 and 3 (P = 0.014). These results suggest that pulpotomy can be used as an alternative treatment for permanent mature teeth diagnosed with pulpitis and that aging is one factor affecting the treatment outcome.
... Preserving dentin to maintain structural integrity of tooth, while respecting the original root canal anatomy of tooth, must form an integral part of root canal preparation. Preservation of peri-cervical dentine is a key (8) factor in determining the long-term prognosis in these teeth . In addition to their superior fatigue resistance in curved canals and efficient shaping time, TruNatomy files are designed to shape root canal systems with maximum preservation of peri-cervical dentin. ...
... The concept of minimally invasive endodontic treatment involves preserving as much of the root dentin as possible [12]. The use of instruments with a small diameter and taper is advocated to limit the amount of dentin cutting and preserve the cervical dentin [13] to improve resistance to tooth fracture [14]. TruNatomy (TRN; Dentsply Sirona) is a recently launched NiTi rotary system with this concept incorporated into its design features. ...
Selection of an appropriate nickel–titanium (NiTi) rotary system is important for minimally invasive endodontic treatment, which aims to preserve as much root canal dentin as possible. This study aimed to evaluate selected mechanical properties and the root canal shaping ability of TruNatomy (TRN), a NiTi rotary system designed for minimally invasive endodontic shaping, in comparison with existing instruments: HyFlex EDM (HEDM), ProTaper Next (PTN), and WaveOne Gold (WOG). Load values measured with a cantilever bending test were ranked as TRN < HEDM < WOG < PTN (p < 0.05). A dynamic cyclic fatigue test revealed that the number of cycles to fracture was ranked as HEDM > WOG > TRN > PTN (p < 0.05). Torque and vertical force generated during instrumentation of J-shaped artificial resin canals were measured using an automated instrumentation device connected to a torque and vertical force measuring system; TRN exhibited smaller torque and vertical force values in most comparisons with the other instruments. The canal centering ratio for TRN was smaller than or comparable to that for the other instruments except for WOG at the apex level. Under the present experimental conditions, TRN showed higher flexibility and lower torque and vertical force values than the other instruments.
... However, in severe cases of dental pulp exposure or bacterial infection, endodontic treatment is needed to remove the inflamed and/or infected pulp tissue. It has been reported that endodontically-treated teeth are at greater risk of root fracture, compared with teeth with healthy dental pulp tissue [2]. Thus, the preservation of dental pulp tissue by direct pulp capping treatment is worthwhile to lengthen the lifespan of the teeth and could be a great contribution to improve public health [3]. ...
In cases in which dental pulp tissue is accidentally exposed, direct pulp capping is often performed to induce reparative dentin formation. Although macrophages are essential for the inflammatory response and tissue repair, the emergence pattern and the role of macrophages in dental pulp tissue have not been clarified. Here, we investigated the emergence of M1/M2 macrophages in dental pulp tissue after a direct pulp capping and the effects of M2 macrophages on odontoblastic differentiation of the dental pulp stem cell (DPSC) clones. The emergence of macrophages in dental pulp tissue was investigated using a rat direct pulp capping model. Alizarin Red S staining and quantitative RT-PCR was performed to examine the effect of M2 macrophages on the mineralization and odontoblastic differentiation of DPSC clones. Immunohistochemical staining revealed that M1 macrophages were detected in dental pulp tissue after treatment and increased in number at three days after treatment. However, M2 macrophages gradually increased in number in dental pulp tissue after treatment, with the highest level recorded at seven days post-operation. Additionally, conditioned medium from M2 macrophages induced odontoblast-like differentiation of DPSC clones. These results suggest that macrophages play a role in the inflammatory response and reparative dentin formation after dental pulp exposure.
... The retrieval of the separated instrument can result in excessive loss of root canal dentin and leads to vertical root fracture. (7) . ...
... The optimal restoration of endodontically treated teeth has always been very crucial because they are more subjected to failure than vital teeth. 1 This fact is most probably due to reduced amount of remaining sound tooth structure as well as restorative procedures. 2,3 Various approaches were used to restore lost tooth structure, protect and strengthen the remaining part. 4 Post and core supported restorations -through different types 5,6became the classical and traditional way to restore endodontically treated teeth. ...
... 14 Structural integrity of pericervical dentine specifically could be a key factor in determining the long-term prognosis with specific reference to fracture resistance of endodontically treated teeth. 15 The term pericervical dentine was first described by Clark and Khademi 16 and refers to an area roughly 4mm coronal to the crestal bone and 6mm apical to the crestal bone (Fig 1). It is considered to be critical dentine for tooth strength and should be conserved as much as possible to ensure long-term retention of the tooth. ...
Minimally invasive endodontics' specific focus on dentine preservation is gaining popularity. Before deciding on the appropriate endodontic access cavity design, clinicians should investigate the advantages and disadvantages associated with different treatment modalities. The purpose of this article is to provide a summary of possible advantages and disadvantages of different endodontic access cavity designs with the focus on traditional, conservative and ultra-conservative endodontic access cavities, specifically in molar teeth. No conclusive evidence is found in the literature favouring one access cavity design above another and clinicians are advised to evaluate each case individually when deciding on the appropriate access cavity design for that specific case. Fracture resistance, proper shaping in order to facilitate irrigation and disinfection, as well as canal location and orifice detection are some of the contributing factors in selecting an appropriate access cavity design that will be highlighted in this article.
... Fundamentally, the accurate endodontic mechanical preparation must respect the original anatomy without modifying it. Furthermore, shaping should avoid undue dentin reduction to reduce the hazard of microcracks or stripping [18][19][20][21]. It is well established that root canal shaping procedures and rotary instrumentation can generate micro-cracks. ...
Background:
Various irrigation techniques for cleansing the endodontic space have been proposed, and internal heating combined with ultrasonic activation (3D cleaning technique) is considered an effective technique. This prospective multicenter clinical study aims to evaluate healing rates for teeth after root canal treatment utilizing the 3D cleaning technique and to report predictive values for success.
Material and methods:
Ninety patients referred for a root canal treatment were included. All enrolled patients were treated with the 3D cleaning protocol. Four endodontists performed the clinical procedures and follow-up evaluations. Preoperative, postoperative and follow-up data were gathered from the consented patients. Each patient was assessed for any clinical signs or symptoms. Afterwards, two trained, blinded, and independent evaluators scored the subject's periapical radiographs. This score was made by checking for the presence or absence of apical periodontitis using the periapical index (PAI). Then, the teeth were classified as healing or healed and were considered a success based on a cumulative success rate of healing. Statistical analysis was performed using the Fisher's exact test, Pearson correlation, and logistic regression analyses of the preoperative prognostic factors at a 0.05 significance level.
Results:
90 patients were evaluated at two years with a follow-up rate of 97.7%. The cumulative success rate of healing was 95.4%. Eight predicting aspects were identified by employing bivariate analyses. Then, using logistic analyses, the two prognostic significant variables directly correlated to healing were the preoperative presence of periapical index (p value = 0.016).
Conclusions:
In this two-year clinical study, the cumulative success rate of healing was 95.4% when patients were treated with the 3D cleaning protocol.
... Nowadays, all operations in the medical field are aimed basically at the conservation of the human body [7]. In Endodontics, the integrity of the tooth structure is a crucial factor that influences the case prognosis as it is directly related to the functional requirements of the tooth after restoration [8,9]. ...
Objectives: Post-treatment apical periodontitis is an inflammatory disorder of peri-radicular tissues caused by either persistent or secondary intra-radicular infection . The present study compared the prognosis of cases treated with the “selective root retreatment” concept to the traditional retreatment approach. Material and Methods: Forty patients complaining of failed root canal treatment having a periapical lesion in one root were selected. The cases were randomly divided into two groups; group (S): selective root canal retreatment in which only the affected root was retreated and group (T): traditional root canal retreatment in which all canals were retreated. The peri-radicular condition was evaluated radiographically using the Periapical Index (PAI) for one year. The chi-square test statistical tests analyzed the outcome data. Results: At the baseline examination, There was no significant difference between the two groups regarding the patients’ baseline mean periapical indices . After one year, we found that the mean periapical index declined without a significant difference between the two groups. Conclusions: The present study points to selective root retreatment as a successful “minimally invasive alternative” in cases of an independently diseased root. The remaining treated roots can be retained without intervention provided that they are confirmed: “healthy”. Clinical Relevance: Selective root retreatment is a promising conservative option in the treatment of failed endodontic cases with periapical pathosis related to an individual root.
... Fracture of root filled teeth may occur because of the loss of tooth structure and induced stresses caused by endodontic and restorative procedures such as [92]: ...
The prognosis of root filled teeth depends not only on successful root canal treatment but also on having an adequate amount of remaining tooth structure. This chapter discusses the implications of numerous restorative factors on the prognosis of root filled teeth with special emphasis on evidence from clinical studies. Clinical studies assessing the prognosis of root filled teeth have evaluated two main outcomes: survival of the restoration defined as the absence of catastrophic failure; a failure leading to loss of the restoration or tooth, and success—defined as the absence of both catastrophic failure (restoration or tooth loss) and noncatastrophic failures. The chapter also presents detailed information to enable effective clinical decision making. Based on the summarised findings, restorative recommendations and good practice statements can be formulated to simplify clinical decision‐making. Successful root canal treatment and eliminating all the avenues of recontamination are essential for the restoration of the root filled teeth.
... The survival of endodontically treated and restored teeth depends on the amount of remaining coronal structure, restorative procedures, and material selection [26,27]. In particular, the preservation of at least one residual coronal wall or a circumferential 2-mm ferrule effect may contribute to overall tooth mechanical resistance [28]. ...
The aim of this systematic review is to summarize and conclude findings to reveal the stress ranges developed by various post materials by finite element analysis. This, in turn, aids in the selection of better post material clinically. The electronic databases PubMed and Google Scholar were searched in this review by using specific inclusion and exclusion criteria. Among 14586 articles, 22 articles were included in this systematic review, as they satisfied the eligibility criteria. The search covered all articles published from 1997 to December 2021. All records identified were retrieved and imported into the Rayyan bibliographic software, which is a systematic review screening software. Later, data extraction and analysis of 22 articles were done. Twenty-two articles, which were all finite element analysis studies, were included. Among these, 18 studies used maxillary central incisor scanned models, two studies used a maxillary canine model, and the remaining two used the mandibular premolar model for finite element analysis. All these tooth models are restored with post models made of different materials. This systematic review revealed a difference in stress distribution in endodontically treated teeth when using different post materials. Among 22 studies, 15 studies evaluated glass fiber posts and the results showed that they induce less stress on restored endodontically treated teeth when compared to other posts, with maximum stress concentration at the cervical third of the root. Prefabricated posts like stainless steel and Titanium showed more stress on the restored tooth structure with stress concentration at the cervical and apical third of the root. Prefabricated zirconia also showed more stress on the restored tooth with maximum stress concentration at the middle third of the root.
... Traditional access cavity designs for various tooth types have remained relatively unaltered for decades, with only slight changes addressing convenience form and extension for prevention (4). Consequent tooth structure reduction, coronal to the pulp chamber, along chamber walls, and around canal orifices, may compromise the tooth's resistance to fracture under functional loads (5). Also, a study has found that the remaining tooth structure has a significant association with the outcome of endodontic retreatment (6). ...
Background:
This study evaluated two endodontic access designs (Conservative (Cons) vs Traditional (Trad)) of class I and class II cavities on cusp deflection (CD) and fracture strength (FS) of root canal filled maxillary premolars.
Material and methods:
Seventy-two sound maxillary first premolars were included in this study; Teeth were randomly assigned into nine groups (n=8), a positive control group where teeth left sound and the other eight according to the access cavity designs (Cons class I, Trad class I, Cons class II and Trad class II). After access preparation, teeth were endodontically-treated. Four groups were restored with FiltekTM Bulk-Fill composite. While the other four groups were left without coronal restoration as negative controls for fracture strength. Following thermocycling (500 cycles), CD values were recorded for the restored teeth at the following intervals, after cavity preparation, 15 min after restoration and after thermocycling. The samples were then subjected to fracture using a universal testing machine. The data were analyzed using one-way ANOVA and Tukey Post-Hoc. Statistical significance was set at p<0.05.
Results:
There was a significant difference between groups at 15 min after restoration (p<0.000) and there were no differences after cavity preparation and after thermocycling (p>0.05). At 15 min after restoration, the CD value was significantly higher in Trad class II than in other types of cavities (p<0.05) and there was no difference between Cons and Trad class I (p>0.05). In each group, the CD value was significantly higher 15 min after restoration compared to that after cavity preparation and after thermocycling in all groups. The highest FS was recorded for the control group (1240 N), while the lowest was for the Trad class II not restored group (472.8 N). One-way ANOVA test showed a highly significant difference between groups (p<0.000) and there were no significant differences in FS between the Cons vs Trad access cavity designs in class I and class II cavities, respectively.
Conclusions:
Cusp deflection increased by the increase in the size of cavity preparation and stress relaxation tends to occur after thermocycling. Moreover, the conservation of the endodontic access cavity could improve the resistance of the tooth to fracture compared to its traditional counterpart but not to a statistically significant point. Key words:Conservative, traditional, endodontic access cavity, cusp deflection, fracture strength.
... Conventional endodontic access cavity: Different studies have shown that the long-term survival of root-canal-treated teeth is often associated with major restorations. 24,25 Therefore, saving tooth structure when performing conventional access cavities is critical. The DNS has been evaluated for conventional endodontic access cavities. ...
This scoping review (SCR) was conducted to map the existing literature on dynamic navigation system (DNS), to examine the extent, range, and nature of research activity. Additionally, this SCR disseminates research findings, determines the value of conducting a full systematic review with meta-analysis, and identifies gaps in the existing literature and future directions. This SCR followed Arksey and O'Malley's five stages framework. The electronic search was performed in PubMed (Medline), Scopus (Elsevier), and Web of Science (Clarivate Analytics) databases using a search strategy. Five themes emerged during the descriptive analysis that captured the DNS application in endodontics. The DNS has been explored for creating access cavities (8/18, 44.44%), locating calcified canals (4/18, 22.2%), microsurgery (3/18, 16.6%), post removal (2/18, 11.1%), and intraosseous anesthesia (1/18, 5.5%). Out of the 18 studies included, 12 are in vitro (66.6%), five are in vivo (case report) (27.7%), and one is ex vivo (5.5%). The DNS demonstrated accuracy and efficiency in performing minimally invasive access cavities, locating calcified canals, and performing endodontic microsurgery, and it helped target the site for intraosseous anesthesia.
... To get a rewarding result, there should be a balancing between preservation and removing of dentine during instrumentation . (2) Another important paraameter is a dissinfection of the root canal system. Ideal instrumentation and disinfection play a major rule in the healing of periradicular tissue and root canal tratment success (3). ...
... A number of publications have recommended full coverage crowns following endodontic therapy for posterior teeth so as to reduce the risk of fracture, provide a coronal seal when cemented with resin cement, avoid bacterial infection, and restore function. 12,13 Here, as compared to full coverage crowns where proximal reductions are done and subgingival margins are prepared here only occlusal surface is prepared without proximal reduction, once the customized restoration is prepared it will be easily seated to the patient's tooth after minimal preparation and sealed with digital workflow provides a highly precise and easy manufacturing process. 7 Studies by Bindl and Mormann and Schmitter et al. stated that this minimally invasive approach is easy to perform, and can decrease failures related to endodontically treated molars. ...
... Es habitual atribuir mayor debilidad y fragilidad a los dientes tratados endodónticamente frente a los dientes vitales (Schwartz and Robbins 2004). Existen varios factores que afectan a la fuerza de dichos dientes, incluyendo la excesiva pérdida de tejido dentario debido a caries, trauma dentoalveolar, deshidratación de la dentina, preparación del acceso endodóntico, la propia instrumentación e irrigación del conducto radicular, al igual que la preparación para la rehabilitación post endodóntica (Tang et al. 2010;Sedgley and Messer 1992). Haga clic o pulse aquí para escribir texto. ...
El propósito del presente estudio fue evaluar in vitro la resistencia a la fractura de incisivos centrales superiores, obturados con gutapercha y dos diferentes selladores endodónticos. Se analizaron 60 incisivos centrales superiores extraídos con los ápices completos e intactos, así como con ausencia de tratamiento de conducto. Se procedió a decoronar a las muestras obteniendo segmentos de raíces de 15mm y se las dividió en tres grupos (n=20) según el sellador utilizado en la obturación: sellador resinoso (AH Plus), sellador biocerámico (Endosequence), dientes sanos (grupo control). Los dientes fueron obturados con la técnica de cono único. Posteriormente se incubó a las muestras por 7 días y se las sometió a fuerzas controladas de compresión en una máquina de ensayo universal a un rango de 1mm/min hasta fracturarse la raíz. La resistencia a la fractura fue medida en Newtons. Se evidenció que el mayor valor de resistencia lo presentan los dientes sanos con 865,55N; seguido por los dientes obturados con sellador biocerámico con 617,35N y el menor valor de resistencia se observó en los dientes obturados con sellador resinoso con 543,20N (p < 0.05). Se observó que no hay diferencias estadísticamente significativas (ANOVA y prueba de Tuke) y en la resistencia a la fractura entre los selladores evaluados.
... Prosthetic restoration should be applied to posterior teeth with endodontic treatment and excessive crown destruction, for reasons such as reducing tooth breakage and bacterial contamination. 1 In these cases, post-core and crown restoration, which is a traditional treatment method, is generally applied. However, this treatment may reduce the fracture resistance of the tooth, cause root perforations and elongation of the chairside. ...
Aim: As a result of large coronal destruction in endodontically treated teeth, significant losses occur in the dentin tissue around the pulp and the need for prosthetic treatment occurs. In this case series, endocrown applications produced in a single session with CAD/CAM system are presented as an alternative to crown restoration traditionally applied to premolar and molar teeth with excessive crown destruction. Case Series: In first case, 38-years-old male patient number 25, 46-years-old female patient number 36 in our second case, 21-years-old female patient number 46 in our third case, 26-years-old male patient number 46 in our fourth case, and in the last case 52-years-old male patient tooth number 15 has been applied to root canal treatment. As a result of the clinical and radiological examinations of the patients, it was observed that there were no systemic diseases. Endocrown restoration was considered appropriate and recommended to patients with less dentin tissue. Firstly, teeth are prepared for endocrown restoration. Afterwards, the impressions were digitalized by scanning the jaws with an intraoral optical scanner (Cerec Omnicam, Dentsply Sirona, USA). The restorations were designed with the help of the CEREC 4.3 software (Dentsply Sirona, USA) and the milling process was carried out using the feldspathic ceramic block (Vita Mark II, Vita Zahnfabrik, Germany) in the same session by CEREC inLab MC XL (Dentsply Sirona, USA). Later, the restorations were glazed and cemented with dual polymerized resin cement (RelyX Ultimate, 3M ESPE, USA). Conclusion: Endocrown restorations are a minimally invasive, conservative treatment approach that provides mechanical adhesion to the pulp chamber and cavity walls with adhesive resin cement and allows the preservation of the remaining tooth structure. For this reason, it is a treatment option that can be preferred instead of post-core and crown application in teeth with root canal treatment.
... Only minimal changes have been made throughout time to the typical endodontic cavity preparation for different kinds of teeth [2]. The tooth's ability to break under helpful stresses may be weakened if the necessary tooth structure is expelled during the cavity preparation procedure [3,4]. Extraction is the most common consequence of cracks in teeth treated with endodontics [5][6][7]. ...
Introduction:
Endodontic access cavity preparation plays a vital role as preservation of enamel structure is of utmost importance for a tooth's strength to be maintained. As teeth become fragile after a root canal therapy, this study was designed to compare in vitro the fracture resistance of root-filled and restored teeth with traditional endodontic access cavity, conservative endodontic access cavity (CEC), ninja endodontic access cavity (NEC), and truss endodontic access cavity (TEC).
Materials and methods:
Control (intact teeth) and traditional endodontic access cavity as well as CEC, NEC, and TEC groups were each given a new human mandibular molar that was freshly removed. Cone beam computed tomography (CBCT) scans of the cone beam showed the values of CEC, NEC, and TEC. After that the teeth were endodontically treated and repaired. To test the specimens, universal testing equipment was used. In order to avoid tooth breakage, the maximum load was determined. Statistical analysis was used in the form of Kolmogorov-Smirnov and Levene tests, which were used to examine data for typical dispersion and consistency in change.
Results:
Intact teeth showed the highest resistance to fracture compared with other groups. TEC showed significantly higher resistance to fracture compared to the CEC design.
Conclusions:
It is possible, within the restrictions of this research, to infer that the TEC design enhanced tooth fracture strength in comparison with the CEC design.
... Root dentine treatment with various solutions may change the structural and chemical composition of the dentine, which may cause alteration in the dentine solubility and permeability [4]. Such alteration may influence the bonding capability of the adhesive agents to the dentine [5]. ...
Aim: The study aims to evaluate the effect of different irrigant and ultrasonic activation on the push-out bond strength of glass fiber post to the root dentine. Materials and Methods: Palatal roots of sixty-four maxillary first molar teeth were sectioned at 14 mm and instrumented with ProTaper Next rotary system up to X4 and obturated with AH Plus sealer and gutta-percha size X4. After post space preparation, the samples were divided into eight groups (n=8) according to the post space irrigation as follow; normal saline (control group), normal saline with ultrasonic activation, 5.25% NaOCl, 5.25% NaOCl with ultrasonic activation, 2% chlorhexidine, 2% chlorhexidine with ultrasonic activation, 17% EDTA and 17% EDTA with ultrasonic activation. RelyX fiber posts were cemented with RelyX U200 cement, the samples were sectioned horizontally, and two slices were obtained from each sample. A push-out test was performed using the Universal testing machine at a speed of 0.5mm/min. The statistical analysis involved One-way ANOVA with post hoc Bonferroni test and Student's t-test. Results: irrigation protocol significantly affected the bond strength (p < 0.001), EDTA showed the highest bond strength and NaOCl showed the lowest bond strength. Ultrasonic activation did not significantly improve the bond strength (P>0.05). The apical regions have significantly higher bond strength than coronal regions (p < 0.001). Conclusion: post space irrigation with 17% EDTA significantly improved the bond strength of fiber post to root dentine using self-adhesive cement, while the ultrasonic activation of the irrigant solutions had no effect on the bond strength.
... This unavoidable loss of dentine weakens the root and creates increased susceptibility to fracture [20]. There is evidence that these teeth have reduced levels of proprioception which could have impaired normal protective reflexes which leads to fracture [21]. ...
Aim: To evaluate the effect of different intra orifice barrier materials on fracture resistance of endodontically treated teeth and to determine which amongst them is best suitable. Materials and Method: 45 mandibular premolars were decoronated to a standardized length, prepared and obturated with gutta-percha and AH Plus sealer. Except for control group, the coronal 3-mm gutta-percha was removed and filled with RMGIC and Biodentine. Fracture resistance of the specimens was tested. Result: Fracture resistance of roots was affected significantly by the type of IOB used and the following pattern was observed: RMGIC > Biodentine > Control Group. Conclusion: Presence of IOB increases the fracture resistance of endodontically treated teeth as compared to teeth without IOB. RMGIC showed the maximum reinforcement.
... An ideal post that approximates the structure of physiological dental dentin would be easy to insert, would not require large sacrifices of dental hard substance in the preparation of the radicular canal, would make the stresses during masticatory functions evenly distributed, and would be as aesthetically pleasing as possible [54,55]. So far, the closest is the fiberglass post, which fulfils many of the characteristics of the ideal post and has a modulus of elasticity similar to that of the tooth [56]. ...
The purpose of this study was to show the improved outcomes of restoring endodontically treated teeth with fiberglass posts compared to restorations using metal posts. In our study, we used the Finite Element Method (FEM), which is based on the principle that a physical model that supports a given load distributes the stress throughout its volume. We sought to assess what stress results in a tooth when it is restored using a fiberglass post compared to restoration using a metal post. The finite element analysis showed that a system consisting of a tooth with a fiberglass post is more stable in terms of the maximum stress than a system consisting of a tooth with a metal post. The maximum displacements and deformations were obtained in the case of a canine restored with a fiberglass post, which showed that this system had a high elasticity, therefore, higher strength than a canine restored with a metal post, which had high rigidity.
... The reasons for cusp fracture have been extensively advocated as abrupt impact trauma taking place from epileptic fits and laryngoscope misapplication and fatigue failure of tooth structure caused by recurrent stress overloading. Usual functional stresses may cause cusp fractures in occasions of lower mechanical properties, from reduced tooth structure resulting from caries, tooth wear, and operative dentistry techniques, and from fluctuations in tooth structure due to aging, vital pulp tissue loss, and endodontic treatment [14,15]. ...
... However, endo-dontically Treated teeth's restoration of structure, aesthetics, and function is accompanied with various issues2, which may be attributed to the severe loss of the structure of tooth (dentin) while preparation of access cavity, which reduces their fracture toughness when in mastication. 3,4 To prevent endodontic complications, the structure of the tooth is eliminated in a restricted manner in traditional root canal access cavity design (TEC) preparation. 5 After post obturation restoration, however, dentine loss and anatomical tooth structures namely tooth cusps, marginal ridge, and floor of pulp chamber could result in fracture of tooth. ...
Aim of study is to evaluate the fracture resistance of the root canal treated Mandibular 1st and 2nd molar teeth with Conventional(TEC) access design and Truss(TREC) access design restored with composite resin and subjected to thermocycling. Method: 60 human 1st and 2nd molar (mandibular) teeth were randomly categorised into six (6) groups: CON (GroupI), TEC (GroupIII), TREC(GroupV) not subjected to thermocycling whereas CONTC (GroupII),TECTC(GroupIV) and TRECTC(GroupVI) subjected to thermocycling. Biomechanical preparation of the canals were done upto #F3 of Protaper gold rotary files (Dentsply) and obturated using gutta-percha points and restored using SDR bulk-fill composite(Dentsply). All samples were then subjected to thermo-cycling for 5000cycles between 15°C and 45°C for different time intervals and their fracture toughness tested under an Universal Tester with steel ball of diameter 5mm at a constant 1mm/min speed. Two-way and one-way ANOVA test employed for statistical analysis. Result: The fracture strength of teeth in TREC group had no notable variation with the control group (P>0.05) without thermocycling. Both TEC and TREC designs notably reduced the fracture toughness after thermocycling (P<0.05). The least fracture resistance was noted in TECTC group. Conclusion: TREC ought to increase the fracture resistance of root canal treated teeth after thermocycling.
Combined crown and post-and-core treatment often requires multiple intermittent appointments and takes a long time. This article describes a novel method for simultaneously fabricating a custom glass fiber post-and-core and the corresponding crown. The critical step, defined as a post-and-core virtual try-in, is to construct a virtual crown abutment that mimics the profile of a real one gained after post-cementation and tooth preparation. The fully digital workflow optimizes the treatment and saves time by accomplishing restorations on the first visit.
Introduction:
The purpose of this study was to determine the volume of dental tissue removed during endodontic access preparation with cone-beam computed tomography (CBCT) comparing two different software.
Methods and materials:
CBCT images of 20 teeth were obtained before and after endodontic access performed with spherical and conical diamond burs. The images were taken with i-CAT Precise system with 0.25 mm voxel size. Digital Imaging and Communications in Medicine (DICOM) images were loaded on two different software programs (Materialise® and InVersalius®), and a 3D reconstruction of the CBCT images was performed on both programs. The baseline volume (BV), and the final volume (FV) were obtained, and the lost tissue volume (LV) was calculated using the formula: LV=BV-FV. The t-test was used to compare initial and final volumes and also to compare the two programs, using a significance level of 5%.
Results:
The volumetric data calculated for the Materialise and the InVesalius programs were, respectively: BV-mean of 441.79±85.08 mm3 and 442.01±84.83 mm3; FV-mean of 426.75±83.88 mm3 and 426.94±83.75 mm3; LV-mean of 15.04±4.32 mm3 and 15.07±4.16 mm3. No statistically significant difference was found in the volumes calculated by either program for initial, final, or removed tissue (P>0.05). However, there was a significant difference between the BV and LV calculated on the same program (P<0.05).
Conclusion:
Our in vitro study showed that CBCT was able to determine the volume of dental tissue removed in the endodontic access preparation of extracted human teeth, regardless of the software program used.
Introduction: Tooth fracture is one of the most undesirable phenomena in Endodontically Treated Teeth (ETT) and usually leads to tooth extraction. Basically, removal of any hard tissue from the canal walls raises the chance of root fracture.
Aim: To evaluate the impact of root canal taper on fracture resistance of ETT prepared by two different file systems (Hero Shaper and RaCe file systems).
Materials and Methods: This in-vitro study was conducted in the Department of Conservative Dentistry and Endodontics at Bharati Vidyapeeth (Deemed to be University) Dental College and Hospital, Sangli and Praj Metallurgical Laboratory Pune, Maharashtra, India, frome February 2021 to November 2021. The study included 44 freshly extracted mandibular premolar teeth were randomly divided into four groups. Group 1a had Hero Shaper 4%, group 1b had 6% Hero Shaper, group 2a had RaCe 4% and group 2b had RaCe 6% file system. After cleaning and shaping the root canals, obturation was completed using cold lateral compaction and root canals were embedded in standardised autopolymerising acrylic resin blocks, subjected to a vertical load in universal testing machine to cause vertical root fracture. The forces required to induce fractures were measured in Newtons. Data was analysed by using independent t-test and two-way Analysis of Variance (ANOVA) test for intergroup comparison. A p-value≤0.05 was considered as statistically significant.
Results: Among instrumented groups, group 1a (Hero Shaper 4%) showed higher fracture resistance of 372.5 Newtons and group 2b (RaCe 6%) showed lowest fracture resistance of 314.56 Newtons as compared to other groups. Statistically significant difference (p-value=0.026) was seen in the mean fracture resistance among the group 1a and 1b, and group 2a and 2b. At pair wise comparison there was statistically significant difference in group 1a and group 2a (p-value=0.016).
Conclusion: Amongst the instrumented groups, Hero Shaper file system showed the higher fracture resistance, than RaCe file system. Marked reduction in fracture resistance of ETT was seen with the use of greater taper instruments.
The aim of the present study was to evaluate the fatigue to cyclic and static resistance of indirect restorations with different preparation designs made either of lithium disilicate (LS) or polymer-infiltrated ceramic network (PICN). Eighty-four (n = 84) molars were chosen, endodontically treated, and prepared with standardized MOD cavities. The molars were randomly divided into 6 study groups (n = 14) taking into account the “preparation design’’ (occlusal veneer with 1.2 mm occlusal thickness; overlay with 1.6 mm occlusal thickness; adhesive crown with 2 mm occlusal thickness) and the “CAD/CAM material’’ (E-max CAD, Ivoclar vivadent; Vita Enamic, Vita). A fatigue test was conducted with a chewing simulator set at 50 N for 1,500,000 cycles. Fracture resistance was assessed using a universal testing machine with a 6 mm diameter steel sphere applied to the specimens at a constant speed of 1 mm/min. A SEM analysis before the fracture test was performed to visually analyze the tooth-restoration margins. A statistical analysis was performed with a two-way ANOVA and a post-hoc pairwise comparison was performed using the Tukey test. The two-way ANOVA test showed that both the preparation design factor (p = 0.0429) and the CAD/CAM material factor (p = 0.0002) had a significant influence on the fracture resistance of the adhesive indirect restorations. The interaction between the two variables did not show any significance (p = 0.8218). The occlusal veneer had a lower fracture resistance than the adhesive crown (p = 0.042) but not lower than the overlay preparation (p = 0.095). LS was more resistant than PICN (p = 0.002). In conclusion, in the case of endodontically treated teeth, overlay preparation seems to be a valid alternative to the traditional full crown preparation, while occlusal veneers should be avoided in restoring non-vital molars with a high loss of residual tooth structure. LS material is more resistant compared to PICN.
Introduction
The purpose of this study was to evaluate and compare two different access cavity designs in combination with two popular single-file preparation systems to see which combination preserves dentin, and more specifically pericervical dentin, best. Minimum remaining dentin thickness and dentin volumes were evaluated pre- and post-instrumentation.
Methods
60 extracted, human mandibular molars were selected and randomly divided into two different access cavity design preparation groups: traditional access cavities (n=30) and conservative access cavities (n=30). Within each cavity preparation design group, the 30 teeth were divided into two instrumentation groups (WaveOne Gold Primary (n=15) and TruNatomy Prime (n=15)). Samples were scanned using micro-Computed Tomography imaging before and after access cavity preparation as well as after final endodontic instrumentation. Pericervical remaining dentin thickness and dentin volume changes were evaluated and compared.
Results
Conservative access cavity designs resulted in more favourable remaining dentin thickness. The least amount of mean dentin volume loss was also recorded in the conservative access cavity preparation groups regardless of the preparation instrumentation.
Conclusion
In terms of remaining pericervical dentin thickness and dentin volume reductions, the authors conclude that conservative access cavity designs preserve dentin best.
This chapter reviews the current evidence on minimally invasive endodontics, based on a solid foundation of the basic principles. The main goal of root canal treatment is the prevention or treatment of apical periodontitis for long‐term retention of a functional tooth. Minimum intervention dentistry always begins with detection, diagnosis, and then prevention/control strategies. Root filled teeth may fail either because of microbial or structural causes. A deep, cavitated carious lesion in dentine can cause pain, be a potential stagnation site for a dysbiotic plaque biofilm, and lead to structural/functional issues and ultimately poor aesthetics, all requiring restorative intervention. Root canal treatment is corelated with tissue removal during access cavity preparation and instrumentation. This tissue is irreplaceable and cannot be regenerated. Initial microsurgical techniques, however, address apical periodontitis through tissues that can be regenerated. In some cases, microsurgical treatment approaches are less invasive than nonsurgical techniques.
Purpose:
To evaluate the influence of the thickness and type of computer-aided design and computer-aided manufacturing (CAD-CAM) material on the fatigue resistance and failure mode of endodontically treated teeth (ETT) restored with occlusal veneers (OV).
Materials and methods:
Seventy-five (N = 75) ETT were restored with Herculite XRV in the endodontic access. Five experimental groups (n = 15) were tested. Four groups had two different thicknesses (0.6-0.7 mm or 1.4-1.6 mm) and two different CAD-CAM materials: zirconia-reinforced lithium-silicate (LS/Celtra Duo) and composite resin (RC/Cerasmart). The fifth group (control) did not have occlusal veneers. All the specimens were subjected to accelerated fatigue (5 Hz frequency) with an occlusal load increasing up to 1800 N and 131,000 cycles. The number of cycles was recorded when the machine stopped or at the completion of the test. Fatigue resistance was analyzed using the Kaplan-Meier survival test (95% significance level, log-rank post-hoc pairwise comparisons). The samples were categorized according to failure mode. The CAD-CAM materials were examined through scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).
Results:
No differences were found between the thicknesses, regardless of the type of the CAD-CAM material. The thick LS OV outperformed the RC and control groups. The thin RC OV and control groups showed a higher percentage of repairable and possibly repairable failures than the other groups. LS was more homogeneous under SEM, and the EDS analysis detected Si and Zr, but not Li.
Conclusions:
A larger thickness did not improve the resistance of the CAD-CAM materials. Thick LS showed a higher cumulative survival rate to fatigue than the RC and control groups. The direct composite alone (control) survived similarly to the experimental groups, except for the thick LS. This article is protected by copyright. All rights reserved.
maintaining optimal moisture control is a necessary component in the delivery of high quality restorative and endodontic treatment.
Introduction:
This study aimed to characterize the effectiveness of dentin-conditioning with bio-mineralizable chitosan-hydroxyapatite precursor (CS-HA) nanocomplexes alone or associated with tricalcium silicate sealer (TCS/CS-HA) on the mechanical property and antibiofilm efficacy in root dentin.
Methods:
Flow tests were performed following ISO6876:2012-specifications. Solubility was measured. Micromorphology was assessed using Scanning Electron Microscopy (SEM). Nanohardness/elastic modulus were also determined. Fracture resistance was determined on lower premolars that were prepared, and randomly distributed among 7-groups (n=8/group), including the control, CS-HA dentin-conditioning and root canal filled groups. Similar canal preparation/distribution procedure was followed to test the antibacterial effect on Enterococcus faecalis-infected roots. Descriptive statistic was used to report SEM findings. Flowability results were analyzed using Paired t-test. Multiple comparisons from solubility, fracture and antibacterial assays were assessed by one-way ANOVA-Tukey's tests.
Results:
TCS/CS-HA showed optimal flow and no effect on solubility after immersion for 4 weeks (p>.05). TCS/CS-HA significantly increased nanohardness and elastic modulus (210±11.3MPa, 7.9±0.9GPa) compared to TCS (44.5±7.8MPa, 2.1±0.3GPa,p<.05). SEM revealed needle-shaped mineralized structures resulting in fewer voids and a well-adapted sealer-dentin interface in the TCS/CS-HA groups. NaOCl-EDTA irrigation resulted in reduced fracture resistance (444.34N) while CS-HA dentin-conditioning alone (928.28N, p<.05) and CS-HA dentin-conditioning plus CS-HA/TCS resulted in higher fracture resistance (1134.06N, p<.05). CS-HA dentin-conditioning also reduced bacteria by 2.04 log (4.50±0.43) from the initial bacterial load (6.54±0.07, p<.05). There was further bacterial reduction when CS-HA-conditioned root canals were filled with TCS or TCS/CS-HA (0.00 to 0.98±0.57, p>.05).
Conclusion:
Dentin modification with CS-HA increased the fracture resistance of root dentin, and decreased the residual bacterial burden. TCS/CS-HA potentiated the nanomechanical and physical properties of TCS.
Background:
Vertical root fracture (VRF) is one of the most common reasons for tooth extraction, although various methods have been applied for saving teeth with VRF.
Case summary:
This case report describes a woman who had a sinus tract on the labial gingiva of the left maxillary central incisor for past two months. Periodontal probing revealed an 8-10 mm deep, narrow, isolated pocket on the palatal side of the tooth. Clinical and radiographic examination confirmed a longitudinal root fracture. A new approach using a combination of resin and iRoot BP Plus through intentional replantation was used for the treatment of the tooth. At one-year follow-up, the tooth remained asymptomatic with normal periodontal probing depth, and radiographic images showed almost normal bone and periodontal structures around the root.
Conclusion:
This new approach may be developed as an effective method for saving teeth with VRF.
This in vitro study evaluated the fracture resistance of weakened human premolars (MOD cavity preparation and pulp chamber roof removal) restored with condensable resin composite with and without cusp coverage.
Thirty human maxillary premolars were divided into three groups: Group A (control), sound teeth; Group B, wide MOD cavities prepared and the pulp chamber roof removed and restored with resin composite without cusp coverage; Group C, same as Group B with 2.0 mm of buccal and palatal cusps reduced and restored with the same resin. The teeth were included in metal rings with self-curing acrylic resin, stored in water for 24 h and thereafter subjected to a compressive axial load in a universal testing machine at 0.5 mm/min.
The mean fracture resistance values +/- standard deviation (kgf) were: group A: 151.40 +/- 55.32, group B: 60.54 +/- 12.61, group C: 141.90 +/- 30.82. Statistically significant differences were found only between Group B and the other groups (p<0.05). The condensable resin restoration of weakened human premolars with cusp coverage significantly increased the fracture resistance of the teeth as compared to teeth restored without cusp coverage.
The results showed that cusp coverage with condensable resin might be a safe option for restoring weakened endodontically treated teeth.
This study evaluated the fracture resistance of weakened roots restored with glass fiber posts, composite resin cores and complete metal crowns. Thirty maxillary canines were randomly divided into 3 groups of 10 teeth each: teeth without weakened roots (control); teeth with partially weakened roots (PWR) and teeth with and largely weakened roots (LWR). The control group was restored with glass fiber posts and a composite resin core. Teeth in the PWR and LWR groups were flared internally to standardized dimensions in order to simulate root weakness. Thereafter, the roots were partially filled with composite resin and restored in the same way as in the control group. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis of the tooth until failure. Data were analyzed by one-way ANOVA and Dunnett's test for multiple comparisons (p=0.05). There were statistically significant difference differences (p<0.01) among the groups (control group = 566.73 N; PWR = 409.64 N; and LWR = 410.91 N), with significantly higher fracture strength for the control group. There was no statistically significant difference (p>0.05) between the weakened groups. The results of this study showed that thicker root dentin walls significantly increase the fracture resistance of endodontically treated teeth.
The purpose of this study was to determine the elastic modulus of components at the resin-dentin interface with the use of an ultrasound device. Dentin slabs were obtained from freshly extracted bovine incisors shaped into a rectangular form. After demineralization, the dentin specimens were immersed in adhesives and polymerized. Adhesives were also polymerized and trimmed into the same shape as the dentin slabs. The specimens were then immersed in distilled water at 37 degrees C for up to one year. The ultrasound equipment employed in this study was a Pulser-Receiver, transducers and an oscilloscope. By measuring the longitudinal and shear wave sound velocities, the elastic modulus was determined. When the elastic modulus of adhesive resin-infiltrated demineralized dentin was compared with that of adhesives, slightly but significantly lower values were found for adhesives used in a self-etching primer system. On the other hand, a higher elastic modulus was observed for resin-infiltrated dentin than for an adhesive used in an etch and rinse system. The elastic modulus of the resin-infiltrated dentin prepared with the etch and rinse system was affected by long-term storage in distilled water.
The quality of apical seal with regard to the length of remaining gutta-percha following post-space preparation is still controversial. The purpose of this in vitro study was to compare three different lengths of remaining gutta-percha for apical seal after post-space preparation. A total of 126 single-rooted extracted maxillary human anterior teeth with intact apices, straight roots, and without resorption were used in this study. The root canals were prepared and filled with gutta-percha and AH26 sealer. The post-space preparation was accomplished. Ninety-six teeth were randomly divided into three groups (4, 5 and 6 mm of gutta-percha was retained in group 1, 2 and 3, respectively).Thirty teeth were considered for the control groups in which 5 teeth served as positive and 5 teeth served as negative controls. The specimens were placed in India ink for 48 hours and then divided into two halves. The amount of leakage was observed and measured with a stereomicroscope at x 16 magnification and 0.1 mm accuracy. The results showed that there were significant differences among the three experimental groups (P < 0.05). The best apical seal after post-space preparation was associated with the maximum length of remaining gutta-percha in the apical portion of the treated teeth.
Upper premolars restored with endodontic posts present a high incidence of vertical root fracture (VRF). Two hypotheses were tested: (1) the smaller mesiodistal diameter favors stress concentration in the root and (2) the lack of an effective bonding between root and post increases the risk of VRF. Using finite element analysis, maximum principal stress was analyzed in 3-dimensional intact upper second premolar models. From the intact models, new models were built including endodontic posts of different elastic modulus (E = 37 or E = 200 GPa) with circular or oval cross-section, either bonded or nonbonded to circular or oval cross-section root canals. The first hypothesis was partially confirmed because the conditions involving nonbonded, low-modulus posts showed lower tensile stress for oval canals compared to circular canals. Tensile stress peaks for the nonbonded models were approximately three times higher than for the bonded or intact models, therefore confirming the second hypothesis.
The purpose of this study was to compare endodontically versus nonendodontically treated teeth with respect to clinical features, including patient age and gender and tooth types of vertical root fractures.
A total of 315 consecutive cases of vertical root fracture occurring in 274 Chinese patients during a 1 3-year period were reviewed. Age and gender, as well as tooth type and root distribution of vertical root fractures, were presented and compared in endodontically versus nonendodontically treated teeth.
Most patients (87%) had 1 fractured tooth; the others had 2 or 3 fractured teeth. Of all vertical root fractures, 40% occurred in nonendodontically treated teeth. In comparison with those in endodontically treated teeth, vertical root fractures in nonendodontically treated teeth tended to occur in patients with a higher mean age (55 years vs. 51 years) and were more frequent in male patients (78% vs. 58%). Vertical root fractures occurred in nonendodontically treated teeth more often in molars (84% vs. 53%), less often in premolars (16% vs. 33%), and seldom in anteriors (1 tooth vs. 27 teeth).
Vertical root fractures in nonendodontically treated teeth are not uncommon and comprise a large proportion of such fractures in Chinese patients. Differences between endodontically and nonendodontically treated teeth in patient age and gender, as well as in tooth types of vertical root fractures, were demonstrated.
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Finucane D, Kinirons MJ. Non-vital immature permanent incisors: factors that may influence treatment outcome. Endod Dent Traumatol 1999; 15: 273–277. © Munksgaard, 1999.
Abstract — This study examines the treatment of non-vital immature permanent incisors using the calcium hydroxide apexification tecnique. The objectives of the present study were to determine the speed and location of bamer formation and those factors discernible at presentation and during treatment which may be related to it. Forty-four non-vital immature incisors undergoing calcium hydroxide apexification were reviewed in detail. All cases were reviewed every 8–12 weeks for up to 18 months, or until apexification occurred. Details of the time and nature of the injuries and treatment were recorded. The degree of apical development prior to treatment was assessed, and barrier formation, location and time were noted. Mean time to barrier formation was 34.2 weeks (range 13–67 weeks). The strongest predictor of rapid barrier formation was the rate of change of calcium hydroxide and a barrier also formed more rapidly in cases with narrower initial apical width. There was evidence of displacement and a higher mean time for barrier formation in half of the cases. The presence of an abscess was the weakest predictor of rapid barrier formation and the effect was not significant (P=0.280). The barrier was located at the apex in 28 cases (63.6%) and the distance from the barrier to the apex for the remaining 16 (36.4%) varied from 1 mm to 5 mm. The number of placements of calcium hydroxide varied from 1 to 4 with a mean of 1.9, and there was a higher mean number of calcium hydroxide placements in the cases where the barrier was located at the apex.
Cracked tooth syndrome (CTS) is a common occurrence in modern general practice. This article reviews the forces placed on the human dentition and the effect restorative dentistry has on the strength of tooth structure. The study reports on the incidence of CTS in a general practice, finding a far higher incidence in teeth which have not. marginal ridge restored than those which have had the marginal ridge restored those which have not. The various types of treatment modalities advocated and their relative merits are discussed.
The prognosis of root-filled teeth depends not only on the success of the endodontic treatment but also on the amount of remaining dentine tissue, and the nature of final restoration. Fractures of restored endodontically treated teeth are a common occurrence in clinical practice. This article outlines the mechanisms and risk factors for fracture predilection in endodontically treated teeth. Different mechanisms of fracture resistance in dentine and the biomechanical causes of fracture predilection in restored endodontically treated teeth are described. Furthermore, dentinal, restorative, chemical, microbial, and age-induced factors that predispose restored endodontically treated teeth to fracture are also reviewed.
The frequency of cusp fracture of endodontically treated premolars was investigated in a retrospective study. After endodontic therapy, the teeth were either restored with a MOD amalgam filling, or with an enamel-bonded MOD resin filling. A very high frequency of cusp fracture was found in premolars restored with amalgam: nearly one-third fractured within 3 years after endodontic treatment. The frequency of cusp fracture differed among the 4 amalgam-restored teeth; the lower first premolar had a 15-year survival rate of 74%, in contrast to an average of 32% for the other 3 premolars. No resinrestored premolar fractured during the first 3 years, and the difference between amalgam and resin-restored teeth was highly significant at the 0–3 year interval. However, fracture of resin-restored premolars did happen in the following 3–10 year interval. From a periodontal point of view, a low frequency of cusp fracture carries great weight, and it is therefore concluded that an enamelbonded resin filling may be a treatment option much preferred to amalgam in temporarily restoring endodontically treated premolars with MOD cavities.
The aim of this study was to evaluate the effect of cavity design and glass fiber posts on stress distributions and fracture resistance of endodontically treated premolars. Fifty extracted intact mandibular premolars were divided into 5 groups (n = 10): ST, sound teeth (control); MOD, mesio-occlusal-distal preparation + endodontic treatment (ET) + composite resin restoration (CR); MODP, mesio-occlusal-distal + ET + glass fiber post + CR; MOD2/3, mesio-occlusal-distal + two thirds occlusal-cervical cusp loss + ET + CR; and MODP2/3, mesio-occlusal-distal + two thirds cusp loss + ET + glass fiber post + CR. The specimens were loaded on a cusp slope until fracture. Fracture patterns were classified according to four failure types. Stress distributions were evaluated for each group in a two-dimensional finite element analysis. The fracture resistance of the MODP, MOD2/3, and MODP2/3 groups was significantly lower than the ST and MOD groups (p < 0.05). The loss of dental structure and the presence of fiber post restoration reduced fracture resistance and created higher stress concentrations in the tooth-restoration complex. However, when there was a large loss of dental structure (MODP2/3), the post reduced the incidence of catastrophic fracture types.
Recently, the appropriate, durable bond of adhesive systems and composite resin cements to retain endodontic posts was challenged. The question arises whether it would be possible to place glass fiber posts in a less technique sensitive conventional nonadhesive approach. The influence of nonadhesive, self-adhesive, and etch-and-rinse systems on load capability of postendodontic restorations was studied. Human maxillary central incisors were divided into 4 groups (n = 10). Teeth were endodontically treated and restored by using glass fiber posts luted with different cements/composite resin combinations: (1) RelyX Unicem (3M ESPE, Seefeld, Germany)/Clearfil Core (Kuraray Europe, Duesseldorf, Germany), (2) RelyX Unicem/LuxaCore, (3) zinc phosphate cement/Clearfil, and (4) LuxaCore (DMG, Hamburg, Germany)/Clearfil. A 2 mm-ferrule preparation was performed. All specimens received adhesively luted all-ceramic crowns and were exposed to thermal cycling and mechanical loading before subsequent static loading. Significant differences between the experimental groups regarding load capability and fracture patterns were observed. The conventional non-adhesive post cementation is less reliable to withstand simulated functional forces compared to adhesive approaches.
To investigate the optimum diameter for the tapered post of a cast alloy post-core system relative to the root diameter, when measured at the root face, that is required to minimize both post and root failures.
32 extracted maxillary central incisor teeth were each decoronated perpendicular to the long axis at a point 2.0 mm occlusal to the labial cemento-enamel junction. Following endodontic canal obturation, the teeth were assigned randomly to four equal groups for different diameter tapered post space preparations. Then 1.10, 1.50, 1.70, and 2.00 mm diameter cast Ni-Cr alloy post-cores and complete crowns without ferrules were fabricated. Each root was embedded in a large gypsum stone block and the crown loaded palatally at 135 degrees from the long axis in a universal testing machine at a crosshead speed of 1.0 mm/minute until failure. Results were analyzed using one-way ANOVA with Tukey-Kramer post hoc tests, and Fisher's exact test, with alpha = 0.05 for statistical significance.
Mean failure resistance loads were: 0.60, 0.91, 1.00, and 1.38 kN (P < 0.001). All of the 1.10 mm posts failed, without any root fractures. Conversely, none of the 2.00 mm posts failed, but all of the roots fractured. The optimum post to root diameter ratio to minimize failures was approximately 1:4.
There are different reinforcement methods in restoring root-filled teeth. The aim of this in vitro study was to evaluate the effect of fiber post and cusp coverage on fracture resistance of endodontically treated maxillary premolars directly restored with composite resin.
Seventy-five maxillary premolars were divided into 5 groups (n = 15). Except for the control group (intact teeth), in other groups mesio-occlusodistal (MOD) cavities were prepared after endodontic treatment. In the groups with cusp coverage, both buccal and lingual cusps were reduced up to 2 mm. Then specimens in the experimental groups were prepared as follows: composite resin restoration without post and cusp capping, composite resin restoration without post but with cusp capping, composite resin restoration with post but without cusp capping, and composite resin restoration with post and cusp capping. After finishing and polishing, the specimens were stored in distilled water at 37 degrees C for a week. Subsequent to thermocycling and exertion of compressive forces parallel to the long axes of the teeth at a strain rate of 2 mm/min, data were analyzed by using one-way analysis of variance and chi(2) test.
There were no significant differences in fracture resistance between the groups (P = .057). However, chi(2) test showed statistically significant differences between the groups in failure mode (P < .001). The highest number of favorable fractures was observed in the control group (intact teeth).
Root-filled maxillary premolars, restored with direct resin composite with or without fiber post and cusp capping, had similar fracture resistance under static loading.
To evaluate the effect of ferrule preparation length on the fracture resistance after simulated surgical crown lengthening and after forced tooth eruption of endodontically-treated teeth restored with a carbon fiber-reinforced post-and-core system.
40 extracted endodontically-treated mandibular first premolars were decoronated 1.0 mm coronal to the buccal cemento-enamel junction. The teeth were divided randomly into five equal groups. The control group had no ferrule preparation (Group A). Simulated crown lengthening provided ferrule preparations of 1.0 mm (Group B) and 2.0 mm (Group C). Simulated forced tooth eruption provided ferrule preparations of 1.0 mm (Group D) and 2.0 mm (Group E). After restoration with a carbon fiber post-and-core system, each root was embedded in an acrylic resin block from 2.0 mm apical to the margins of a cast Ni-Cr alloy crown, and loaded at 150 degrees from the long axis in a universal testing machine at a crosshead speed of 1.0 mm/minute until fracture. Data were analyzed using ANOVA with Tukey HSD tests, and Fisher's exact test, with alpha = 0.05.
Mean failure loads (kN) for Groups A, B, C, D and E were: 1.13 (SD = 0.15), 1.27 (0.18), 1.02 (0.11), 1.63 (0.14) and 1.92 (0.19), respectively. Significant differences were shown for the effects of treatment method and ferrule length, with significant interaction between these two sources of variation (P < 0.0001). Increased apical ferrule preparation lengths resulted in significantly increased fracture resistance for simulated forced tooth eruption (P < 0.0001), but not for simulated crown lengthening (P > or = 0.24).
Our aim was to compare the accuracy of cone beam computed tomography (CBCT) scans and periapical radiographs (PRs) in detecting vertical root fractures (VRFs) and to assess the influence of root canal filling (RCF) on fracture visibility. Eighty teeth were endodontically prepared and divided into four groups. The teeth in groups A and B were artificially fractured, and teeth in groups C and D were not. Groups A and C were root filled. Four observers evaluated the CBCT scans and PR images. Sensitivity and specificity for VRF detection of CBCT were 79.4% and 92.5% and for PR were 37.1% and 95%, respectively. The specificity of CBCT was reduced (p = 0.032) by the presence of RCF, but its overall accuracy was not influenced (p = 0.654). Both the sensitivity (p = 0.006) and overall accuracy (p = 0.008) of PRs were reduced by the presence of RCF. The results showed an overall higher accuracy for CBCT (0.86) scans than PRs (0.66) for detecting VRF.
Statement of problem:
Little information exists regarding the outcome of crown build-ups on endodontically treated teeth restored with metal-ceramic crowns or with only a direct-placed composite.
Purpose:
The aim of this study was to evaluate the clinical success rate of endodontically treated premolars restored with fiber posts and direct composite restorations and compare that treatment with a similar treatment of full-coverage with metal-ceramic crowns.
Material and methods:
Subjects included in this study had one maxillary or mandibular premolar for which endodontic treatment and crown build up was indicated and met specific inclusion/exclusion criteria. Only premolars with Class II carious lesions and preserved cusp structure were included. Subjects were randomly assigned to 1 of the following 2 experimental groups: (1) teeth endodontically treated and restored with adhesive techniques and composite or (2) teeth endodontically treated, restored with adhesive techniques and composite, and then restored with full-coverage metal-ceramic crowns. Sixty teeth were included in the first group and 57 in the second. All restorations were performed by one operator. Causes of failure were categorized as root fracture, post fracture, post decementation, clinical and/or radiographic evidence of marginal gap between tooth and restoration, and clinical and/or radiographic evidence of secondary caries contiguous with restoration margins. Subjects were examined for the listed clinical and radiographic causes of failure by 2 calibrated examiners at intervals of 1, 2, and 3 years. Exact 95% confidence intervals for the difference between the 2 experimental groups were calculated.
Results:
At the 1-year recall, no failures were reported. The only failure modes observed at 2 and 3 years were decementations of posts and clinical and/or radiographic evidence of marginal gap between tooth and restoration. There was no difference in the failure frequencies of the 2 groups (95% confidence interval, -17.5 to 12.6). There was no difference between the number of failures caused by post decementations and the presence of marginal gaps observed in the 2 groups (95% confidence intervals, -9.7 to 16.2 and -17.8 to 9.27).
Conclusion:
Within the limitations of this study, the results upheld the research hypothesis that the clinical success rates of endodontically treated premolars restored with fiber posts and direct composite restorations after 3 years of service were equivalent to a similar treatment of full coverage with metal-ceramic crowns.
The purpose of this study was to compare the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Forty extracted mandibular premolars with straight roots were randomly selected and mounted on resin blocks with simulated periodontal ligaments, and the apex was exposed. The teeth were divided into four groups of 10 teeth each for different canal preparation techniques and instrumentation lengths: group A: step-back preparation (SB) with stainless steel files (SF) using root canal length (RCL) to guide instrumentation length; group B: SB using RCL - 1 mm; group C: crown-down preparation (CD) with Profile using RCL; and group D: CD with PF using RCL - 1 mm. Digital images of the instrumentation sequence were compared for each tooth. Statistical analysis revealed a significant effect of instrumentation length (p < 0.05) but no significant effect of preparation technique (p > 0.05) on the development of apical cracks.
The purpose of this study was to compare the incidence of dentinal defects (fractures and craze lines) after canal preparation with different nickel-titanium rotary files. Two hundred sixty mandibular premolars were selected. Forty teeth were left unprepared (n = 40). The other teeth were prepared either with manual Flexofiles (n = 20) or with different rotary files systems: ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland), ProFile (Dentsply-Maillefer), SystemGT (Dentsply-Maillefer), or S-ApeX (FKG Dentaire, La Chaux-de-Fonds, Switzerland) (n = 50 each). Roots were then sectioned 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects was noted. There was a significant difference in the appearance of defects between the groups (p < 0.05). No defects were found in the unprepared roots and those prepared with hand files and S-ApeX. ProTaper, ProFile, and GT preparations resulted in dentinal defects in 16%, 8%, and 4% of teeth, respectively. Some endodontic preparation methods might damage the root and induce dentinal defects.
Endodontic therapy is a predictable treatment, resulting in up to 97% retention rate for the treated teeth. However, about 3% of endodontically treated teeth require further treatment, including extraction of the tooth.
This retrospective study analyzed all endodontically treated permanent teeth that were extracted in a multidisciplinary clinic in 2006-2007 (n = 547). Associations among the extractions' indications and the patients' gender, education, and smoking status, as well as tooth type and coronal restoration, were investigated.
Of the 547 endodontically treated teeth that were subjected to extraction, mandibular (44.6%) and maxillary (20.5%) first molars were the most common. Fifteen percent of the extracted teeth were restored with a crown, whereas 57.4% of the extracted teeth did not have a permanent coronal restoration. The reasons for extraction were nonrestorable caries (61.4%), endodontic failure (12.1%), vertical root fracture (8.8%), iatrogenic perforation (8.8%), periodontal disease (4.6%), unrestorable cusp fracture (2.4%), orthodontic (1.3%), and prosthetic (0.2%) considerations and dental trauma (0.5%). Periodontitis was more prevalent among current smokers than among nonsmokers (P < .05). Gender and education had no influence on the extraction of the tooth. Vertical root fracture was more prevalent in mandibular than in maxillary first molars (P < .05). Caries was more prevalent in unrestored teeth than coronally restored or crowned teeth (P = .001). Endodontic failure and VRF were more prevalent in restored than in unrestored teeth (P < .05).
The most common extracted tooth profile was the mandibular first molar without permanent coronal restoration, which was lost due to caries destruction. Endodontically treated teeth were prone to extraction mainly due to nonrestorable carious destruction and to a lesser extent to endodontic-related reasons such as endodontic failure, VRF, or iatrogenic perforation.
This study evaluated the fracture resistance of endodontically treated teeth restored with prefabricated carbon fiber posts and varying quantities of coronal dentin. Sixty freshly extracted upper canines were randomly divided into groups of 10 teeth each. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis. Data were analyzed by 1-way analysis of variance and Tukey test (alpha = .05). Significant differences (P < .001) were found among the mean fracture forces of the test groups (positive control, 0 mm,1 mm, 2 mm, 3 mm, and negative control groups: 1022.82 N, 1008.22 N, 1292.52 N, 1289.19 N, 1255.38 N, and 1582.11, respectively). These results suggested that the amount of coronal dentin did not significantly increase the fracture resistance of endodontically treated teeth restored with prefabricated carbon fiber post and composite resin core.
The results of this study add to the previous findings on the cracked tooth syndrome. Treatment to prevent further cracking is a must. Dentists should be aware of the syndrome and, after making the diagnosis, initiate necessary treatment.
Fabrication of posts and cores for fixed partial denture (FPD) and removable partial denture (RPD) abutment restorations is common in dentistry. The biocompatibility of various post and core techniques with the restorations was clinically evaluated according to location and function. In this study, 154 post and core constructions for 150 patients were observed for a 3-year period to determine if the function of the original restorations remained unsatisfactory. The following techniques were included: (1) screw post and light-curing composite resins, (2) cemented post with parallel sides and light-curing composite resins, and (3) a cast and core technique. Seventeen of the 154 restorations failed; four failures were attributed to root fractures, three to radicular caries, and five to crown dislodgement, while five failures were from detachment of the post and core from the root. The statistical analysis revealed that only the factor "type of abutment" (RPDs and FPDs) had some effect on the failure of the restorations.
The cumulative survival rate (retention of both cusps) and the fracture pattern of 1639 endodontically treated posterior teeth were assessed in a retrospective study. All teeth had an MO/DO or an MOD cavity restored with amalgam without cuspal overlays. The 20-year survival rate of teeth with an MO/DO cavity was markedly higher than that of teeth with an MOD cavity. The lowest survival rate was found for the upper premolars with an MOD cavity: 28% of these teeth fractured within 3 years after endodontic therapy, 57% were lost after 10 years, and 73% after 20 years. Generally, the cusp most prone to fracture was the lingual one, and lingual fractures caused significantly more damage to the periodontal tissues than did facial or total crown fractures. The severity of periodontal damage increased with posterior location of the tooth. By far the most serious failures, irrespective of the cavity type, were found for the upper second molar, as 10 of 29 fractures led to extraction. It is concluded that amalgam, especially in MOD cavities, is an unacceptable material for restoration of endodontically treated posterior teeth if used without cuspal overlays.
In this study, I review, clinically and radiographically, 303 patients with 460 single or multirooted endodontically treated teeth. In all teeth, the therapy was performed by me with the use of final restoration of the crown with or without post and full cast crown coverage after treatment. The teeth were functioning for at least 3 years, without having received any other type of dental work since then. I evaluated the existence of vertical root fracture, the function of the teeth, the type of root canal therapy, the type and length of the post, and the type of retention of the post used in all 460 teeth. After statistical evaluation of the results, I found that 3.69% of the teeth had had vertical root fracture. Computer analysis, simple correlation hypothesis, and distribution method with 1 degree of freedom revealed significant correlation between vertical root fracture and the technique of instrumentation and obturation of the canal (p = 0.025), the length of the post (p = 0.05), and the existence of the post (p = 0.05). On the contrary, I found no correlation between root fracture and type of retention of the prefabricated post used with respect to the method of obturation.
Endodontically-treated posterior teeth are susceptible to fracture; consequently, full-occlusal-coverage restorations are recommended. We designed this study to examine the potential for alternative restorative techniques for pulpless teeth, using strain gauges mounted on extracted maxillary second premolars to measure strains generated by nondestructive occlusal loading. Cuspal stiffness was evaluated on the following sequentially performed procedures: unaltered tooth, completion of all endodontic procedures, appropriate restorative preparation, and restoration. The restorative procedures evaluated were: (1) amalgam, (2) cast gold onlay, (3) composite restoration with enamel etch, and (4) composite restoration with enamel and dentin etch. Finally, all teeth were loaded to fracture. Cast gold was the strongest restorative material tested (2.11 relative stiffness, compared with that of the unaltered tooth at 1.00), and amalgam was the weakest (0.35 relative stiffness). Composite restoration and enamel plus dentin etch were almost as strong as the unaltered tooth (0.87 relative stiffness), while enamel-etch-only yielded lower stiffness (0.51).
The effect of calcium hydroxide treatments and apicaldiameter on the time of apexification and type of apical barrier was studied in 51 pulpless immature permanent incisors. The apical diameter ranged from 2 to 3.5 mm. The root canals were debrided before receiving a calcium hydroxide treatment (Calasept). Patients were recalled monthly for evaluation. The root canals were reinjected with Calasept whenever voids were evident radiographically.
An apical barrier developed in 96% of the teethwithin 3 to 10 months and the types were 65% cap, 25% bridge, and 10% ingrown wedge.
Many of the teeth, 78%, developed an apical barrierwithin the 5- to 6-month period. There were fewer Calasept treatments regardless of the apical diameter, when apexification was faster.
Apical leakage was analyzed quantitatively in extracted teeth with varied levels of remaining gutta-percha. The effect of the method of gutta-percha removal on the apical seal was also evaluated. Ninety teeth were prepared so that 30 teeth had 3 mm of gutta-percha, 30 teeth had 5 mm, and 30 teeth had 7 mm. An additional 75 teeth were divided into three groups of 25 each. A different method of gutta-percha removal was used for each group: hot instrument, mechanical rotary instrument, and chemical solvent. An electrochemical method was used to analyze apical microleakage. Measurements of leakage of each sample were obtained at 24-hour intervals for 30 days. The data suggest that the mechanical method is the most desirable for gutta-percha removal in post preparation. As the level of gutta-percha increased to 7 mm the degree of leakage decreased. At least 5 mm of gutta-percha is necessary for an adequate apical seal.
Twenty-five extracted human central incisors were divided into five groups and prepared for complete cast crowns. Test teeth had cast dowel cores fabricated with the ferrule height varying from 0.5 to 2.0 mm in 0.5-mm increments. The five control teeth did not have cast dowel cores. A 4.0-kg load was applied to each of the restored teeth at an angle of 135 degrees to the long axis of each tooth. This load was applied cyclically at a rate of 72 cycles per minute. The load application point was predetermined by a waxing jig that was used to wax all crowns. The primary variable was the ferrule length. The independent variable was the number of load cycles required to create preliminary failure. Preliminary failure was defined here as the loss of the sealing cement layer between crown and tooth. An electrical resistance strain gauge was used to provide evidence of preliminary failure. The results of this study showed that the 0.5 mm and 1.0 mm ferrule lengths failed at a significantly lower number of cycles than the 1.5 mm and 2.0 mm ferrule lengths and control teeth.
The dental records of 638 patients treated with 788 posts and cores were studied to analyze failure rate and failure characteristics for two post designs. Frequency of the technical failures, loss of retention, root fracture, and post fracture were recorded 4 to 5 years after post cementation. There were two types of posts: custom-cast tapered posts and parallel-sided serrated posts. The cumulative failure rate was 15% for 456 tapered posts and 8% for 332 Para-Post posts. Loss of retention was the most frequent reason for failure for both types of posts, whereas root fractures had the most serious consequences, and all resulted in extraction. A significantly higher success rate was recorded for parallel-sided serrated posts, compared with custom-cast posts, regarding the total failure rate and the severity of the failure (p < 0.05).
Vertical root fractures have been reported to occur primarily in endodontically treated teeth due to condensation forces and/or with post placement. This study describes 11 Chinese patients with 12 molars that developed vertical root fractures without endodontic or post procedures. These showed characteristics of a true vertical root fracture as confirmed after extraction. Fractured teeth showed a consistent pattern. The majority were severely attrited mandibular molars in males. All had clinically intact crowns with no or minimal restorations.