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Alveolar bone regeneration in post-extraction socket: A review of materials to postpone dental implant
Abstract
Tooth extraction usually involves alveolar bone loss and reduction in height and width of the remaining alveolar socket, owing to the physiological bone resorption. This occurrence may perform an inadequate bone profile, that make difficult orthodontic applications, compromising the functional and aesthetic restoration of dental implants. The present review will provide an update on the biological and clinical profile of materials currently in use and those under investigation, in the recovering of bone margins of edentulous sockets.
... Autogenous bone is transferred from one position to another within the same individual. Autografts are biocompatible and have the potential to form new bone through osteogenesis, osteoinduction, and osteoconduction [24][25][26][27][28] However, autogenous bone grafts present several disadvantages, such as a limited amount of material, donor site morbidity, unpredictable bone quality, and post-operative discomfort [26]. Autogenous grafts can be cortical, cancellous, or cortico-cancellous. ...
... Autogenous grafts can be cortical, cancellous, or cortico-cancellous. Cancellous autogenous bone is generally preferred, as it is rapidly re-vascularized and integrated into the acceptor site [27]. ...
... Cortical bone autografts are associated with a greater rate of apposition replacement and bone matrix resorption that can form foci of necrotic tissue [27]. Autogenous bone can be obtained from intra-oral or extra-oral sites and can be used in block or particulate forms [28]. ...
Alveolar ridge bone resorption is a biologic phenomenon that occurs following tooth extraction and cannot be prevented. This paper reviews the vertical and horizontal ridge dimensional changes that are associated with tooth extraction. It also provides an overview of the advantages of ridge preservation as well as grafting materials. A Medline search among English language papers was performed in March 2015 using alveolar ridge preservation, ridge augmentation, and various graft types as search terms. Additional papers were considered following the preliminary review of the initial search that were relevant to alveolar ridge preservation. The literature suggests that ridge preservation methods and augmentation techniques are available to minimize and restore available bone. Numerous grafting materials, such as autografts, allografts, xenografts, and alloplasts, currently are used for ridge preservation. Other materials, such as growth factors, also can be used to enhance biologic outcome.
... Additionally, the target position of anterior teeth is constrained by the craniofacial hard tissues. Therefore, understanding the anatomical factors limiting tooth movement is crucial to mitigate potential harm to roots and alveolar bone during orthodontic treatment [6][7][8]. ...
Objective
To explore the horizontal impact of extensive incisor retraction on alveolar bone and to investigate the relationship of changes in alveolar bone thickness (ΔBT) with horizontal retraction distance of the incisal edge (HRD) and horizontal retraction distance of alveolar ridge crest (HRD’) in orthodontic treatment.
Materials and methods
This retrospective study included 84 patients who underwent orthodontic extraction treatment, involving extensive incisor retraction (≥ 3 mm). Pre-treatment (T0) and post-treatment (T1) cone-beam computed tomography (CBCT) data were collected. The samples were divided into adult (> 18 years) and adolescent (≤ 18 years) groups. Changes in the horizontal alveolar bone thickness in the incisor region, as well as changes in HRD and HRD’, were measured at T0 and T1. Data were statistically analyzed using SPSS 27.0, utilizing paired and independent samples t-tests.
Results
After extensive retraction, both upper and lower central incisors exhibited increased buccal alveolar bone thickness, while lingual and total alveolar bone thicknesses decreased. The horizontal plane near the root apice exhibited overall thickening of the alveolar bone. The tooth roots consistently remained upright within the alveolar bone, maintaining a stable relative position. The magnitude of ΔBT was smaller compared to the changes in HRD and HRD’.
Conclusion
Alveolar bone thickness decreased during extensive retraction, especially near the alveolar crest, with less noticeable variations closer to the tooth root apices. The stable positioning of incisors within the alveolar bone indicates that the alveolar bone changes were primarily morphological, and suggests that partial tooth movement resulted from bone deformation. (Registration Number: ChiCTR2000034288; Approval Date: 01/07/2020)
... Although PRP has been used extensively in various fields of dentistry, showing vast advantages and applications [15,16], the efficacy of PRP on OTM acceleration remains controversial based on the current limited evidence. Therefore, more well-designed randomized controlled trials involving humans are called for to obtain more clinically significant conclusions. ...
Background
The use of platelet-rich plasma (PRP) in dentistry was entered several decades ago, yet its clinical use in orthodontics still requires further investigation. The aim of this study was to evaluate the possible effects of local injection of PRP on the rate and type of mandibular second molar protraction movement compared with the comparator (no PRP) group.
Material and methods
Eighteen patients aged between 17 and 25 years were randomly allocated in a split-mouth study design to receive PRP injections on one side immediately before the start of molar protraction (PRP group), while the other side received only saline solution (comparator group). Eligibility criteria included bilaterally extracted mandibular first molars cases and indicated mandibular second molars protraction. The primary outcome of the study consisted of measuring the rate of molar protraction from the beginning of protraction (T0) to the end of the seventh month (TF), using a digital gauge. The secondary outcome included measuring the type of second molar protraction movement between T0 and TF by lateral cephalometric images. Randomization of the intervention side was performed by picking out opaque sealed envelopes. The blinding of the principal investigator was impossible but blinding of the patient was achieved by injection of saline. Analyses were done using paired samples T-test to compare the changes in all variables between T0 and TF. The level of significance was taken at a P-value < 0.05.
Results
No significant difference was detected between the PRP and comparator groups in the rate of second lower molar protraction during seven months (0.56±0.07 mm per month in the comparator group, whereas, was 0.6±0.11 mm per month in the PRP group). Molar protraction parameters in both groups showed second lower molars moving by controlled tipping closer to bodily movement (Root Movement:Crown Movement≈0.8).
Conclusions
Platelet-rich plasma (PRP) is ineffective in accelerating the rate of orthodontic tooth movement (OTM) during molar protraction, and it has no effect on the type of tooth movement. In addition, the mechanics that we used (6 mm power arm in combination with miniscrews) are effective in mandibular second molar protraction by controlled tipping closer to bodily movement.
... Tooth extraction may also lead to alveolar bone loss, conditioning the need for restoration of bone and soft tissues [90]. In the study on alveolar bone regeneration in a tooth extraction model in rats by Jin et al., absorbable gelatin sponge enriched with PEI-alginate/pBMP-2 was implanted into post-extraction sockets [17]. ...
Treatment of a wide variety of defects in the oral and maxillofacial regions requires the use of innovative approaches to achieve best outcomes. One of the promising directions is the use of gene-activated materials (GAMs) that represent a combination of tissue engineering and gene therapy. This approach implies that biocompatible materials will be enriched with gene-carrying vectors and implanted into the defect site resulting in transfection of the recipient’s cells and secretion of encoded therapeutic protein in situ. GAMs may be presented in various designs depending on the type of material, encoded protein, vector, and way of connecting the vector and the material. Thus, it is possible to choose the most suitable GAM design for the treatment of a particular pathology. The use of plasmids for delivery of therapeutic genes is of particular interest. In the present review, we aimed to delineate the principle of work and various designs of plasmid-based GAMs and to highlight results of experimental and clinical studies devoted to the treatment of periodontitis, jaw bone defects, teeth avulsion, and other pathologies in the oral and maxillofacial regions.
... For an objective evaluation of bone tissue defects, the area of the bone defect sections was measured ( Figure 6G,H). Tooth extraction usually involves alveolar bone loss and reduction in height and width of the remaining alveolar socket, owing to the physiological bone resorption [34]. Therefore, a value of the total bone volume is an important parameter characterizing bone repair. ...
A technology to create a cell-seeded fibrin-based implant matching the size and shape of bone defect is required to create an anatomical implant. The aim of the study was to develop a technology of cell-seeded fibrin gel implant creation that has the same shape and size as the bone defect at the site of implantation. Using computed tomography (CT) images, molds representing bone defects were created by 3D printing. The form was filled with fibrin glue and human dental pulp stem cells (DPSC). The viability, set of surface markers and osteogenic differentiation of DPSC grown in fibrin gel along with the clot retraction time were evaluated. In mice, an alveolar bone defect was created. The defect was filled with fibrin gel seeded with mouse DPSC. After 28 days, the bone repair was analyzed with cone beam CT and by histological examination. The proliferation rate, set of surface antigens and osteogenic potential of cells grown inside the scaffold and in 2D conditions did not differ. In mice, both cell-free and mouse DPSC-seeded implants increased the bone tissue volume and vascularization. In mice with cell-seeded gel implants, the bone remodeling process was more prominent than in animals with a cell-free implant. The technology of 3D-printed forms for molding implants can be used to prepare implants using components that are not suitable for 3D printing.
... An ideal bone-grafting material should not only have a good biocompatibility and biodegradability but also be able to produce bone by osteogenesis, osteoinduction and osteoconduction [23]. Besides, their mechanical properties should be equivalent to or better than those of natural bone [24]. ...
The purpose of this study was to explore the different effects between biomimetic mineralized collagen (MC) and ordinary physically blended hydroxyapatite/collagen (HA/Col) composite in evaluating new bone formation and regenerated bone height in human extraction sockets. Thirty-four patients who cannot retain teeth caused by trauma or decay were randomly selected from Department of Stomatology of Dongzhimen Hospital from December 2013 to December 2014. The patients were randomly divided into two groups. After the operation of tooth extraction, 17 patients were implanted with biomimetic MC (MC group), and other 17 patients were implanted with ordinary physically blended nHA/Col composite (nHA/Col group). X-ray positioning projection by auto-photographing was taken to test the distance between the lowest position and the neighboring CEJm-CEJd immediately, 1 month and 3 months after the operation. The height of new bone formation of the MC group was significantly higher than the nHA/Col group. Biomimetic MC showed better clinical outcomes in the bone formation for extraction site preservation and would have broad application prospect in the field of oral and maxillofacial surgeries.
... DBM is considered as a good osteoinductor in bone grafting biomaterials (Giannoudis et al.; Zimmermann & Moghaddam). Osteoinductivity occurs when the graft material has properties to induce pluripotent mesenchymal cells, derived from the recipient site or from the circulation, to differentiate into osteoblasts, stimulating bone neogenesis (Porrini et al., 2011;Umulis et al., 2009). ...
Autogenous bone grafts are considered to be the gold standard in bone regeneration because of their osteogenic activity; however, due to limited availability of intraoral donor sites and the need to resolve the demands of patients requires an alternative to these. Two male patients were submitted to implant surgery in two stages with 6 months intervals between each of them: the first was exodontia and placement of DBM graft into the socket; the second stage was the drill with a 2 mm internal diameter trephine in center of the alveolar ridge previously grafted with DBM and subsequent implant placement. The samples were analyzed under histological techniques. A very mature bone was observed at 6 months after DBM graft placement in the sockets, showing it to be a good alternative as bone graft.
... DBM is considered as a good osteoinductor in bone grafting biomaterials (Giannoudis et al.; Zimmermann & Moghaddam). Osteoinductivity occurs when the graft material has properties to induce pluripotent mesenchymal cells, derived from the recipient site or from the circulation, to differentiate into osteoblasts, stimulating bone neogenesis (Porrini et al., 2011;Umulis et al., 2009). ...
Autogenous bone grafts are considered to be the gold standard in bone regeneration because of their osteogenic activity; however, due to limited availability of intraoral donor sites and the need to resolve the demands of patients requires an alternative to these. Two male patients were submitted to implant surgery in two stages with 6 months intervals between each of them: the first was exodontia and placement of DBM graft into the socket; the second stage was the drill with a 2 mm internal diameter trephine in center of the alveolar ridge previously grafted with DBM and subsequent implant placement. The samples were analyzed under histological techniques. A very mature bone was observed at 6 months after DBM graft placement in the sockets, showing it to be a good alternative as bone graft.
Background
Alveolar ridge preservation (ARP) is a technique that aims to maintain bone volume and minimize resorption after tooth extraction.
Objective
This study aimed to compare the effectiveness of injectable platelet‐rich fibrin (I‐PRF) versus hyaluronic acid (HA) in combination with xenografts for ARP.
Methods
This randomized controlled trial included 36 patients (20 females and 16 males) who required implant placement in the upper arch. The patients were randomly allocated to one of three groups ( n = 12 each): I‐PRF with xenografts, HA with xenografts, or xenografts alone. All patients underwent ARP, and the extraction sockets were sealed with a free gingival graft harvested from the palate, a total of 36 implants were inserted. Cone‐beam CT scans were performed before and 4 months postoperatively to measure radiographic bone gain as the primary outcome. Clinical parameters, including soft tissue thickness and clinical bone width, were evaluated preoperatively, and at 4 months and 1 year postoperatively. Additionally, histological assessment of core bone biopsies was performed 4 months postoperatively using histomorphometric analysis to determine the percentages of newly formed bone, mature bone, and residual grafts.
Results
Regarding the radiographic bone gain 4 months postoperative the HA group exhibited the highest value (9.78 ± 0.87), which was significantly greater than the values observed in the I‐PRF and control groups (8.60 ± 1.27 and 7.99 ± 0.89, respectively) (one‐way ANOVA, p = 0.007). Crestal bone loss was significantly higher in the control group (−0.98 ± 0.18) than in the I‐PRF group (−0.53 ± 0.11) and HA group (−0.33 ± 0.15) groups (one‐way ANOVA, p < 0.001). In the histomorphometric analysis, the mean area fraction of newly formed bone trabeculae was significantly higher in the HA group (56.66 ± 7.35) than in the I‐PRF group (28.74 ± 5.15) and the control group (24.05 ± 3.64) (repeated measures ANOVA, p < 0.001). Additionally, the mean area fraction of residual graft material was higher in the I‐PRF group (6.76 ± 2.59), followed by the control group (2.71 ± 1.24), while the HA group had the lowest value (2.63 ± 1.27) (Repeated measures ANOVA, p < 0.001).
Conclusion
The combination of HA with xenografts yielded better radiographic and histological outcomes in terms of new bone formation and degree of bone maturation than the I‐PRF and control groups. Furthermore, I‐PRF improved soft tissue thickness.
Please note that clinical trial registration was not completed prior to participant recruitment and randomization. The registration link for this trial is https://clinicaltrials.gov/ct2/show/NCT05781529 .
Objective:
The present randomized controlled trial compares for the first time the vestibular socket therapy (VST) to the contour augmentation technique in the management of compromised fresh extraction sockets in the maxillary esthetic zone, regarding mid-facial soft tissue changes (primary outcome), mesial and distal papillae dimensions, horizontal soft tissue changes and labial bone plate thickness at apical, middle and coronal levels (secondary outcomes) over 1-year.
Materials and methods:
Forty participants with single nonrestorable maxillary teeth in the esthetic zone were randomized into two groups; VST (test; n = 20) utilizing vestibular access for guided bone regeneration (GBR) with immediate implant placement, or contour augmentation (control; n = 20) undergoing an initial healing period followed by implant placement with GBR through a conventional access flap.
Results:
All implants were successfully osseo-integrated, except for one implant in the test group. VST showed significantly less mid-facial soft tissue changes of -0.53 ± 1.17 mm versus -1.87 ± 0.69 mm in the control group (p < 0.001). Similarly, changes in mesial papilla (test = -0.64 ± 0.95 mm, control = -1.20 ± 0.81 mm), distal papilla (test = -0.56 ± 1.17 mm, control = -1.26 ± 0.63 mm), horizontal soft-tissue (test = -0.82 ± 0.95 mm, control = -1.84 ± 0.88 mm; p < 0.05) were significantly less in VST. Intra-group comparisons demonstrated a significant increase in labial bone thickness, with no differences between groups. Regression analysis revealed a significant correlation between VST as well as increased coronal bone thickness with the reduction in mid-facial soft-tissue changes.
Conclusion:
The VST showed less soft-tissue changes and could represent an innovative technique for implant placement in the maxillary esthetic zone. Both techniques showed a high implant survival rate and increased bone thickness after 12 months.
Xenograft versus PRF alone or mixed with metformin in horizontal ridge augmentation with split-crest technique for implant installation
We examined alveolar bone samples in the area of on-bone fixation of a free gingival graft performed during surgery in patients aged 37-55 years with a diagnosis of secondary partial adentia of the upper and lower jaws. Six months after fixation of the graft in the alveolar bone, foci of neoosteogenesis were found in the contact zone. They were characterized by the appearance of appositional lines, cords of basophilic osteoblasts, and growing osteons. An immunohistochemical study revealed an increase in the number of CD44+, CD29+, and osteocalcin+ cells in the layer of the outer circumferential lamellae, primary osteons, and the lining of the Haversian canals. TGF-β1+ cells were located in the intertrabecular reticular tissue and wall of microvessels. The results indicate activation of mesenchymal stem cells in the area of localization of the graft and differentiating osteoblasts. The observed osteoinductive effect of free gingival graft is associated with its participation in reorganization in MSC and induction of morphogenetic molecules.
Background/aimsWhen facial trauma involves elderly patients, the possible presence of frailty and comorbidities in victims of trauma may worsen the posttraumatic symptoms and decrease quality of life. The aim of this multicenter study was to assess the quality of life following surgical or non-operative management of maxillofacial trauma in elderly patients.Materials and methodsThis cohort study was based on the administration of validated self-administered questionnaires to all the geriatric patients (70 years or more) with facial fractures from the involved maxillofacial surgical units across Europe, since 1st January 2019 to 31st June 2019. The following questionnaires were administered: SF36 questionnaire; the VFQ-25 questionnaire; the Oral Health Impact Profile – 14 (OHIP14). Outcome variables were VFQ-25 and OHIP-14 results.ResultsA total of 37 patients (14 male and 23 female patients) met the inclusion criteria and were included in the study. Elderly patients had an improvement in almost all the categories examined by the SF-36 questionnaire 6 months after trauma, with the only exception of a worsening as for role limitations due to physical health. An improvement was observed in almost all the categories at SF-36 test. A worsening of scores of OHIP-14 for all the considered dimensions in the whole study population was observed too.Conclusions
Elderly patients following facial trauma experience significant emotional, social, and functional disturbances. We observed that emotional problems, energy/fatigue, social functioning, and generally social limitations played a great role in the decrease of QoL in elderly patients following maxillofacial trauma.
Introduction
The objective of this research was to study the factors associated with the alveolar bone depth mesial to the mandibular third molars (M8) after the mandibular second (M7) and third molars were protracted into the space of the mandibular first molars (M6), which were newly extracted for orthodontic treatment or extracted more than 1 year before treatment.
Methods
This retrospective study included 57 adult patients (mean age 23.40 ± 4.40 years) in whom M6 were newly extracted for orthodontic treatment or extracted more than 1 year before treatment. The alveolar bone depth mesial to M8 was measured on posttreatment panoramic radiographs. The vertical, horizontal, and angular changes of M8 were measured on both pre- and posttreatment panoramic radiographs. Linear correlation and regression analyses were conducted to explore the factors associated with the alveolar bone depth mesial to M8.
Results
The alveolar bone conditions of M6 (R= −0.391, P <0.001) and the vertical movement directions of M8 (R= −0.433, P <0.001) were significant factors associated with the alveolar bone depth mesial to M8 after orthodontic protraction.
Conclusions
Without considering the pretreatment periodontal status of M8, patients with M6 extracted exceeding 1 year before treatment and with M8 extruded after orthodontic protraction may exhibit deeper alveolar bone depth mesial to M8.
Features of rapid loss and inadequate bone mass of alveolar bone after teeth extraction are still great obstacles for a successful subsequential dental implantation. MicroRNA-based therapy, though an advantageous strategy in tissue regeneration, is still not available for alveolar bone due to the unique complicated oral environment which is full of enzymes and electrolytes. In this paper, a microRNA-activated scaffold constituted of microRNA-21 nanoparticles combined with porous Bio-Oss particles was designed for the use of accelerating the early stage healing of the alveolar bone. It was noteworthy that the regeneration of alveolar bone was rapidly promoted to be shortened from the ordinary 3 months to 2 weeks. The nanoparticles designed by us according to the oral environment could protect microRNA from various enzymes and electrolytes attack, leading to a steady, continuous, and efficient delivery of gene. With the aid of porous Bio-Oss, microRNA-21 released in situ and its effects on highly reducing the recovery time and improving the quality of newly formed bone at the alveolar site were confirmed for the first time. Great potential could be seen for the microRNA-mediated biofunctionalized scaffold on the future dental application.
Background:
The authors conducted a retrospective cohort study to investigate external apical root resorption (EARR) and alveolar bone loss (ABL) after protraction of the mandibular molars by using miniscrews.
Methods:
The authors protracted 51 mandibular molars in 37 adults into an edentulous area by using sliding mechanics with a lever arm or a miniscrew-supported root spring. The authors measured root length and alveolar bone height on panoramic radiographs and corrected according to the crown length registration method. The authors measured the amounts of crown movement (CM) and root movement (RM) on the superimposed lateral cephalometric radiographs along the mandibular occlusal plane. The authors used a linear mixed model to determine the risk factors for EARR and ABL.
Results:
All edentulous spaces closed successfully in an average of 31.7 months, and the average CM and RM were 4.97 and 8.64 millimeters, respectively, with an RM:CM ratio of 2.81. The root length decreased significantly by 0.80 mm (5.53%), but EARR of more than 2 mm occurred in only 4.0% of molars. The alveolar bone height was reduced significantly by 0.56 mm, but ABL of more than 2 mm occurred in only 2.0% of molars. Linear mixed model results revealed that EARR and ABL correlated only with RM and age, respectively.
Conclusions:
Protraction of the mandibular molars into an edentulous area by using miniscrews was effective and safe, especially in younger adults.
Practical implications:
Protraction of the mandibular molars can be considered as an alternative treatment to conventional prosthetic treatment in the restoration of edentulous space, especially in young adults, if patients accept longer treatment duration.
Purpose
To evaluate the potential of two bone substitute materials and the influence of different healing periods in guided bone regeneration therapy of osseous defects around implants.
Materials and Methods
Twenty-four edentulous patients received implants in the region of the lost lower incisors. Around two standardized osseous defects were created, treated either with a 50:50 mixture of PepGen P-15® and OsteoGraf®/N-700 (test group) or with BioOss® (control group), and covered with titanium membranes. After healing periods of 2, 4, 6, or 9 months, the implants were removed together with the surrounding bone and subsequently prepared for histological evaluations.
Results
Defect depths in both groups showed a clinical reduction after intervention. The histologically measured distance from the implant shoulder to the first point of bone-implant contact (BIC) after treatment did not differ between the two groups. The healing time influenced the level of the first point of BIC, with a longer healing period producing a more coronal first point of BIC. A greater percentage BIC and a higher fraction of mineralized bone were found in the pristine bone area compared with the augmented defect area.
Conclusion
It can be concluded that in the treatment of osseous defects around oral implants, both materials were equally effective bone substitute materials when used in combination with guided bone regeneration.
The authors conducted a study to assess the quality of systematic reviews (SRs) published on the topic of alveolar ridge preservation (ARP).
The authors conducted a search for SRs on ARP on the basis of a set of eligibility criteria (only SRs involving ARP, with or without meta-analyses, written in English). The authors assessed the quality of the SRs independently of one another by using two established checklists.
The authors selected eight SRs. The results of all of the SRs indicated that ARP was effective in preserving the ridge volume as compared with extraction alone, but it did not fully prevent bone-resorptive events. None of the SRs, however, received the highest possible score in either of the checklists. One SR that had a score of 5 (of a possible 11) using one checklist and 5 (of a possible 14) using the other checklist had the lowest overall score. The results of this assessment revealed that a significant proportion of the investigators in the SRs did not include non-English language articles, perform hand searching of published literature or evaluate the gray literature. Assessment of publication bias and reporting of conflicts of interest also was lacking in some studies. Practical Implications. Although ARP appears to be an effective approach to preventing resorption after tooth extraction, significant structural and methodological variability exists among SRs on this topic. Future SRs on ARP should consider the use of quality assessment checklists to minimize methodological shortcomings for better dissemination of scientific evidence.
In this study we used a biocomplex constructed from dental pulp stem/progenitor cells (DPCs) and a collagen sponge scaffold for oro-maxillo-facial (OMF) bone tissue repair in patients requiring extraction of their third molars. The experiments were carried out according to our Internal Ethical Committee Guidelines and written informed consent was obtained from the patients. The patients presented with bilateral bone reabsorption of the alveolar ridge distal to the second molar secondary to impaction of the third molar on the cortical alveolar lamina, producing a defect without walls, of at least 1.5 cm in height. This clinical condition does not permit spontaneous bone repair after extraction of the third molar, and eventually leads to loss also of the adjacent second molar. Maxillary third molars were extracted first for DPC isolation and expansion. The cells were then seeded onto a collagen sponge scaffold and the obtained biocomplex was used to fill in the injury site left by extraction of the mandibular third molars. Three months after autologous DPC grafting, alveolar bone of patients had optimal vertical repair and complete restoration of periodontal tissue back to the second molars, as assessed by clinical probing and X-rays. Histological observations clearly demonstrated the complete regeneration of bone at the injury site. Optimal bone regeneration was evident one year after grafting. This clinical study demonstrates that a DPC/collagen sponge biocomplex can completely restore human mandible bone defects and indicates that this cell population could be used for the repair and/or regeneration of tissues and organs.
In many cases, the level, positioning and timing of signaling through the bone morphogenetic protein (BMP) pathway are regulated by molecules that bind BMP ligands in the extracellular space. Whereas many BMP-binding proteins inhibit signaling by sequestering BMPs from their receptors, other BMP-binding proteins cause remarkably context-specific gains or losses in signaling. Here, we review recent findings and hypotheses on the complex mechanisms that lead to these effects, with data from developing systems, biochemical analyses and mathematical modeling.
The aims of the current study were to: (1) evaluate the results of vertical guided bone regeneration (GBR) with particulate autogenous bone grafts, (2) determine clinically and radiographically the success and survival rates of 82 implants placed in such surgical sites after prosthetic loading for 12 to 72 months, and (3) compare defects that were treated simultaneously with sinus augmentation and vertical GBR to other areas of the jaw treated with vertical GBR only.
Eighty-two implants were inserted in 35 patients with 36 three-dimensional vertical bone defects. The patients were divided into three groups: single missing teeth (group A), multiple missing teeth (group B), and vertical defects in the posterior maxilla only (group C). All group C subjects were treated simultaneously with sinus and vertical augmentations. All patients were treated with vertical ridge augmentation utilizing titanium-reinforced polytetrafluoroethylene (e-PTFE) membranes and particulated autografts. After removal of the e-PTFE membrane, all sites received a collagen membrane.
At membrane removal, mean vertical augmentation was 5.5 mm (+/-2.29 mm). Mean combined crestal remodeling was 1.01 mm (+/-0.57 mm) at 12 months, which remained stable through the 6-year follow-up period. There were no statistically significant differences between the three groups in mean marginal bone remodeling. One defect had a bone graft complication (2.78%, 95% CI: 0.00%, 8.15%). The overall implant survival rate was 100% with a cumulative success rate of 94.7%.
(1) Vertical augmentation with e-PTFE membranes and particulated autografts is a safe and predictable treatment; (2) success and survival rates of implants placed in vertically augmented bone with the GBR technique appear similar to implants placed in native bone under loading conditions; (3) success and failure rates of implants placed into bone regenerated simultaneously with sinus and vertical augmentation techniques compare favorably to those requiring only vertical augmentation.
Remodeling and resorption of the alveolar crest, specifically at the buccal aspect, characterize the healing extraction socket. These result in narrowing and shortening of the alveolar ridge, which compromise esthetics and complicate restoration. Alveolar ridge augmentation has been proposed to facilitate future site restoration by minimizing ridge resorption. Therefore, the purpose of this study was to compare extraction socket healing and alveolar ridge alteration after socket augmentation using bone allograft covered with an acellular dermal matrix (ADM) or polytetrafluoroethylene (PTFE) membrane.
Twenty non-smoking healthy subjects were selected. Each subject required maxillary premolar, canine, or central incisor tooth extraction. The extraction sites were debrided and grafted with a mineralized bone allograft that was covered with an ADM or PTFE membrane. Postoperative appointments were scheduled at 2, 4, and 8 weeks. After 16 weeks of healing, final measurements were performed, and trephine core biopsies were obtained for histomorphometric analysis. Implants were placed immediately after biopsy harvesting.
Eighteen subjects completed the study. All sites healed without adverse events and allowed for implant placement. PTFE membranes exfoliated prematurely, with an average retention time of 16.6 days, whereas the ADM membranes appeared to be incorporated into the tissues. Buccal plate thickness loss was 0.44 and 0.3 mm, with a vertical loss of 1.1 and 0.25 mm, for ADM and PTFE, respectively. Bone quality assessment indicated D3 to be the most prevalent (61%). Histomorphometric analysis revealed 41.81% versus 47.36% bone, 58.19% versus 52.64% marrow/fibrous tissue, and 13.93% versus 14.73% particulate graft remaining for ADM and PTFE, respectively. No statistical difference was found between the two treatment groups for any of the parameters.
All sites evaluated showed minimal ridge alterations, with no statistical difference between the two treatment modalities with respect to bone composition and horizontal and vertical bone loss, indicating that both membranes are suitable for alveolar ridge augmentation.
It has been close to a century since calcium phosphate materials were first used as bone graft substitutes. Numerous studies conducted in the last two decades have produced a wealth of information on the chemistry, in vitro properties, and biological characteristics of granular calcium phosphates and calcium phosphate cement biomaterials. An in depth analysis of several key areas of calcium phosphate cement properties is presented with the aim of developing strategies that could lead to break-through improvements in the functional efficacies of these materials.
To compare clinically and histologically an allogeneic bone matrix to autogenous bone chips in the vertical ridge augmentation technique using titanium-reinforced e-PTFE membranes.
The study protocol was designed to include patients with bilateral posterior mandibular partial edentulism. Patients were treated with a split-mouth design approach: each side was randomly assigned to the test group (titanium-reinforced e-PTFE membrane and allogeneic bone matrix) or to the control group (titanium-reinforced e-PTFE membrane and autogenous bone chips). Different clinical parameters including the amount of vertically regenerated bone (DSB) and biologic complications were recorded. Histomorphometric analysis and the bone-implant contact percentage were performed.
Five female patients were enrolled in the study. Ten edentulous sites were vertically augmented and 25 implants were inserted (13 test group, 12 control group) with a staged approach. In the test group no membrane was exposed. The mean bone regeneration was 4.70 mm (SD 0.48 mm). All 13 implants appeared clinically stable. In the control group, 1 membrane was exposed after 2 months. The mean crestal bone regeneration was 4.10 mm (SD 0.88 mm). All 12 implants were stable at the abutment connection. Nine biopsy specimens from the regenerated areas were evaluated. Vertical bone regeneration was evident in both groups since all the samples demonstrated trabecular bone with different degrees of maturation and mineralization in the regenerated area.
Within the limits of this study based on 5 patients, it appears that the behavior of the allogeneic bone matrix is similar to that of autogenous bone chips when used for vertical ridge augmentation by means of guided bone regeneration techniques. Both grafts demonstrated analogous histologic characteristics. Nevertheless, long-term clinical studies are needed to confirm these preliminary results.
Three biphasic calcium phosphate (BCP) bone substitute materials with hydroxyapatite (HA)/tricalcium phosphate (TCP) ratios of 20/80, 60/40, and 80/20 were compared to coagulum, particulated autogenous bone, and deproteinized bovine bone mineral (DBBM) in membrane-protected bone defects. The defects were prepared in the mandibles of 24 minipigs that were divided into four groups of six with healing times of 4, 13, 26, and 52 weeks, respectively. The histologic and histomorphometric evaluation focused on differences in amount and pattern of bone formation, filler degradation, and the interface between bone and filler. Collapse of the expanded polytetrafluoroethylene barrier membrane into the coagulum defects underlined the necessity of a filler material to maintain the augmented volume. Quantitatively, BCP 20/80 showed bone formation and degradation of the filler material similar to autografts, whereas BCP 60/40 and BCP 80/20 rather equaled DBBM. Among the three BCP's, the amount of bone formation and degradation of filler material seemed to be inversely proportional to the HA/TCP ratio. The fraction of filler surface covered with bone was highest for autografts at all time points and was higher for DBBM than BCP 80/20 and 60/40 at the early healing phase. TRAP-positive multinucleated cells were identified on BCP and DBBM surfaces without showing typical signs of resorption lacunae.
The preservation of bone volume immediately after tooth removal might be necessary to optimize the success of implant placement in terms of esthetics and function. The objectives of this randomized clinical trial were two-fold: 1) to compare the bone dimensional changes following tooth extraction with extraction plus ridge preservation using corticocancellous porcine bone and a collagen membrane; and 2) to analyze and compare histologic and histomorphometric aspects of the extraction-alone sites to the grafted sites.
Forty subjects who required tooth extraction and implant placement were enrolled in this study. Using a computer-generated randomization list, the subjects were randomly assigned to the control group (EXT; extraction alone) or to the test group (RP; ridge-preservation procedure with corticocancellous porcine bone and collagen membrane). The following parameters were assessed immediately after extraction and 7 months prior to implant placement: plaque index, gingival index, bleeding on probing, horizontal ridge width, and vertical ridge changes. A bone biopsy was taken from the control and test sites 7 months after the surgical treatment. Histologic and histomorphometric analyses were also performed.
A significantly greater horizontal reabsorption was observed at EXT sites (4.3+/-0.8 mm) compared to RP sites (2.5+/-1.2 mm). The ridge height reduction at the buccal side was 3.6+/-1.5 mm for the extraction-alone group, whereas it was 0.7+/-1.4 mm for the ridge-preservation group. Moreover, the vertical change at the lingual sites was 0.4 mm in the ridge-preservation group and 3 mm in the extraction-alone group. Forty biopsies were harvested from the experimental sites (test and control sites). The biopsies harvested from the grafted sites revealed the presence of trabecular bone, which was highly mineralized and well structured. Particles of the grafted material could be identified in all samples. The bone formed in the control sites was also well structured with a minor percentage of mineralized bone. The amount of connective tissue was significantly higher in the extraction-alone group than in the ridge-preservation group.
The ridge-preservation approach using porcine bone in combination with collagen membrane significantly limited the resorption of hard tissue ridge after tooth extraction compared to extraction alone. Furthermore, the histologic analysis showed a significantly higher percentage of trabecular bone and total mineralized tissue in ridge-preservation sites compared to extraction-alone sites 7 months after tooth removal.
The aim of the present study was to qualitatively and quantitatively compare the tissue reactions around four different bone substitutes used in orthopedic and craniofacial surgery. Cylinders of two bovine bone substitutes (Endobon and Bio-Oss) and two coral-derived bone substitutes (Pro Osteon 500 and Interpore 500 HA/CC) were implanted into 5-mm bur holes in rabbit tibiae. There was no difference in the amount of newly formed bone around the four biomaterials. Interpore 500 HA/CC resorbed completely, whereas the other three biomaterials did not undergo any detectable biodegradation. Bio-Oss was osseointegrated to a higher degree than the other biomaterials. Material characteristics obtained by diffuse reflectance infrared Fourier transform spectrometry analysis and energy-dispersive spectrometry did not explain the differences in biologic behavior.
TEN PATIENTS WHO REQUIRED two or more anterior teeth extractions were utilized in this study. Extraction procedures were carried out with a full thickness surgical flap approach. After flap reflection, teeth were removed with a minimum of trauma to the surrounding bone. Following extraction silicone-based impression techniques were used to produce a model of the alveolar process and small metal pins were placed in the alveolus to be used as fixed points to make measurements of ridge dimensions. One socket was covered with an expanded polytetrafluoroethylene (ePTFE) barrier membrane (experimental site); the other socket was a conventional control. The soft tissue flaps were then mobilized using periosteal releasing incision and the wound closed with ePTFE mattress sutures. Six months following extraction, patients were treated with flap surgery to expose both extractions sites to remove the ePTFE membranes and to measure ridge dimensions using the pins as fixed points. Clinical and model measurements have shown statistically significant better ridge dimensions at experimental sites than at control (P < or = 0.05). Three patients with exposed membranes had similar dimensional changes as controls. Results from this study suggested that this improved technique offers a predictable alveolar ridge maintenance enhancing the bone quality for dental implant procedures and esthetic restorative dentistry.
It has been recently observed that in implants with screw-retained abutments, in in vitro as well as in vivo conditions, bacteria can penetrate inside the internal cavity of the implant as a consequence of leakage at the implant-abutment interface. An alternative to screw-retained abutments is represented by implants that can receive cemented abutments. In this case, the abutment goes through a transmucosal friction implant extension (collar) and is cemented inside the internal hexagonal portion of the implant. The aim of the present research was to compare fluids and bacterial penetration in 2 different implant systems, one with cement-retained abutments (CRA) and the other with screw-retained abutments (SRA).
Twelve CRA dental implants and 12 SRA implants were used in this study. The research was done in 3 steps: scanning electron microscopic (SEM) analysis, fluid penetration analysis, and bacterial penetration analysis.
1) Under SEM it was possible to observe in the SRA implants a mean 2 to 7 micron gap between implant and abutment, while in the CRA implants, the gap was 7 micron. In the latter group, however, the gap was always completely filled by the fixation cement. All the spaces between abutment and implant were filled by the cement. 2) With SRA implants, it was possible to observe the presence of toluidine blue at the level of the fixture-abutment interface and the internal threads; the absorbent paper was stained in all cases. With CRA implants, the absorbent paper inside the hollow portion of the implants was never stained by toluidine blue. No penetration of toluidine blue was observed at the implant-abutment interface and inside the hollow portion of the implants. 3) In all the SRA implant assemblies, bacterial penetration was observed at the implant-abutment interface. No bacteria were detected in the hollow portion of the CRA implants.
On the basis of the results obtained in the present study using 2 different implant systems, we conclude that CRA implants offer better results relating to fluid and bacterial permeability compared to SRA implants.
To evaluate the clinical outcome of implants placed into sites grafted with bioactive glass.
Seventeen consecutively treated patients were referred to a private specialist surgical practice for the repair of dentoalveolar defects, and/or ridge maintenance at the site of extraction sockets, prior to implantation. Bioactive glass available in 1 of 2 forms was utilized as an alloplastic grafting material. Bone cores were trephined out at the time of implantation and processed and examined to evaluate the tissue response under the light microscope. Implant mobility, marginal bone levels, and soft tissue health were all evaluated over a 2- to 3-year follow-up period to determine treatment success.
A total of 40 Astra Tech dental implants were placed. The overall success rate at the end of the study was 88.6% for implants that were in function for a mean period of 29.2 months (22 to 24 months). One patient with 5 successful implants died at 18 months after functional loading. At that time the cumulative success rate was 90%. Another patient who was diagnosed with cancer of the large bowel lost 3 implants. If this patient were excluded from the data, the cumulative success rate increases to 96.8%. Mean marginal bone loss measured 0.5 mm mesially and 0.4 mm distally over a maximum follow-up of 36 months. Human histology demonstrated that connective tissue was seen to exist without any inflammatory response, for up to 6 months. Increasing evidence of bone formation was seen in direct relation to the bioactive glass material beyond this time frame.
The need to repair and augment dentoalveolar defects necessitates the use of autogenous bone or a substitute that may be seen to avoid the additional morbidity of a donor site procedure and without risk of cross infection. The use of bioactive glass has been proposed as a viable bone substitute. The current study draws attention to the long healing time required to achieve even a small amount of new bone incorporation into the graft, as seen histologically. However, the high rate of osseointegration and continued medium-term function of implants placed into these grafted sites would indicate that the use of bioactive glass does not prohibit osseointegration. However, it is likely that the initial integration will have derived from those areas in contact with native bone.
Implants will survive for up to 3 years in sites grafted with bioactive glass, even when such grafts appear to only slowly conduct new bone growth.
Implants can be placed at the time of tooth extraction (immediate), after several weeks (delayed), or after complete healing (late). The purpose of this study was to evaluate clinical bone healing of buccal dehiscence-type defects around maxillary implants placed together with bioabsorbable collagen barrier membranes and bone graft at the 3 time points.
Three implant placement protocols were compared: immediate procedures primarily closed by a rotated split palatal flap (19 patients, 23 implants; group 1); delayed sites closed by a rotated (full-thickness) palatal flap at the time of tooth extraction (25 patients, 39 implants; group 2); and late implantation (22 patients, 40 implants; group 3). One to 3 proximal implants were simultaneously placed. Defect height and width were measured at the time of implant placement and at second-stage surgery. Surface area was calculated as half ellipses.
The best results were obtained with delayed implantation. The mean percentage of the reduced defect height for groups 1, 2, and 3 was 77.4%+/-16.92%, 88.8%+/-15.29%, and 75.2%+/-17.99%, respectively, and the mean percentage area of the reduced defect was 90.2%+/-9.15%, 95.6%+/-8.73%, and 87.6%+/-11.48%, respectively. Differences between groups were statistically significant. The mean percentage of the reduced defect height and area was significantly smaller when there was spontaneous implant cover screw exposure. Single rather than multiple implant placement led to significantly better results.
Timing of placement, number of simultaneously placed implants, and spontaneous implant exposure significantly influence clinical bone healing around maxillary implants placed together with augmentation procedures.
This prospective clinical analysis reports on the use of coral granules in alveolar ridge preservation procedures in a population of young, growing patients. The sample consisted of 21 patients, 12 females and 9 males, with a mean age of 13.6 years. These 21 patients had 48 dento-alveolar defects suitable for augmentation with coral granules, and were followed clinically and radiographically for 3-7 years after augmentation. There were two areas of augmentation: 17 defects in the anterior maxilla resulted from traumatic tooth loss, and 31 defects in the posterior maxilla and mandible resulted from the extraction of ankylosed retained primary molars with no permanent succedaneous teeth. Between 1-2 ml of coral granules were implanted into the alveolar bone defects left by the extraction of teeth in both the areas. This was in order to preserve the remaining edentulous ridge from further alveolar ridge resorption. The goal of the procedure was to preserve the alveolus so that in the future, a dental implant could be placed to replace the missing tooth, after jaw growth had stopped, without the need for a bone graft. The coral granules appeared to be totally replaced by the host bone on follow-up clinical and radiographic examinations. The two areas of the jaws behaved quite differently. In the anterior maxilla, where tooth loss was secondary to trauma, the coral granules restored the alveolar ridges temporarily. However, over the years of follow-up in this study, the coral granules failed to provide sufficient bone to support the placement of a dental implant without using a bone graft in 14 of the 17 defects or 82.4% of sites. In the posterior maxilla and mandible, where tooth loss was due to the elective removal of ankylosed primary molars, 29 of the 31 defects or 93.5% of sites were successful as they were able to support the placement of an osseo-integrated dental implant without the use of a bone graft. The alveolar sparing technique was more successful in maintaining an alveolar ridge sufficient for the placement of a dental implant without bone grafting in the posterior maxilla and mandible, where tooth loss was secondary to the elective removal of ankylosed deciduous molars than in the anterior maxilla, where tooth loss was secondary to trauma. Coral granules seem to be more suitable in the posterior maxilla and mandible where there were ankylosed deciduous teeth and congenitally absent permanent teeth than in the traumatized anterior maxilla. In successful sites, coral granules can spare the alveolus from residual ridge atrophy or resorption, obviating the need for a bone graft. This reduces patient morbidity, as a second surgical donor site is avoided because bone graft harvesting is made unnecessary.
Preservation of alveolar bone volume following tooth extraction facilitates subsequent placement of dental implants and leads to an improved esthetic and functional prosthodontic result. The aim of the present study was to assess bone formation in the alveolus and the contour changes of the alveolar process following tooth extraction. The tissue changes after removal of a premolar or molar in 46 patients were evaluated in a 12-month period by means of measurements on study casts, linear radiographic analyses, and subtraction radiography. The results demonstrated that major changes of an extraction site occurred during 1 year after tooth extraction.
Platelet-derived growth factor (PDGF) exerts potent effects on wound healing including the regeneration of tooth-supporting structures. Limitations of topical protein delivery to periodontal osseous defects include transient biological activity and the bioavailability of PDGF at the wound site. The objective of this investigation was to determine the feasibility of in vivo PDGF-B gene transfer to stimulate periodontal tissue regeneration in large tooth-associated alveolar bone defects in rats. Periodontal lesions (0.3 x 0.2 cm in size) were treated with a 2.6% collagen matrix alone or a matrix containing adenoviruses encoding luciferase (control), a dominant negative mutant of PDGF-A (PDGF-1308), or PDGF-B. Block biopsies were harvested at 3, 7, and 14 days post-gene delivery and descriptive histology and histomorphometric analyses were performed. The defects treated with Ad-PDGF-B demonstrated greater proliferating cell nuclear antigen positively stained cells and strong evidence of bone and cementum regeneration beyond that of Ad-luciferase and Ad-PDGF-1308 groups. Quantitative image analysis showed a nearly fourfold increase in bridging bone and sixfold increase in tooth-lining cemental repair in the Ad-PDGF-B-treated sites compared to lesions treated with Ad-luciferase or collagen matrix alone, which showed limited hard tissue neogenesis. In addition, the Xenogen In Vivo Imaging System revealed sustained and localized gene expression of the luciferase reporter at the periodontal lesions for up to 21 days after gene transfer. These results indicate that in vivo direct gene transfer of PDGF-B stimulates alveolar bone and cementum regeneration in large periodontal defects. Gene therapy utilizing PDGF-B may offer the potential for periodontal tissue engineering applications.
Guided bone regeneration using barrier membranes is useful in bone augmentation. Because the commonly used polytetrafluoroethylene (PTFE, Gore-Tex (R), WL Gore, Flagstaff, AZ, USA) membranes or resorbable membranes tend to collapse, more stable membranes are desirable. A titanium membrane (FRIOS(R) BoneShield, Friatec, Mannheim, Germany) was evaluated in a clinical study of 52 patients. Most of them had particulate bone grafts or phycogene hydroxyapatite (Algipore(R), Friatec, Mannheim, Germany) or both stabilized with titanium membranes. In 78 procedures, 23 membranes (29%) became exposed, but only seven of these (9%) led to failure of the graft with a considerable loss of augmented material. The time interval between operation and possibly exposure was responsible for the result. Early exposures (within a few weeks) led to poor formation of new bone within the grafts, whereas if exposure was later, results were as good as in procedures in which the membranes did not become exposed.
To evaluate (i) the effects of rhPDGF-BB on localized ridge augmentation using a natural bone mineral (NBM), and (ii) the influence of a collagen membrane (CM) on factor activity.
Chronic-type alveolar ridge defects (n = 4 dogs) were randomly allocated in a split-mouth design as follows: upper jaw: NBM + rhPDGF-BB + CM (test) vs. NBM + rhPDGF-BB (control), and lower jaw: NBM + rhPDGF-BB + CM (test) vs. NBM + CM (control). After 3 weeks, dissected blocks were prepared for immunohistochemical (angiogenesis - TG) and histomorphometrical analysis [e.g. augmented area (AA), mineralized - (MT), non-mineralized tissue (NMT) (mm(2))].
Lower jaw: TG and mineralization of AA mainly originated from the defect borders. Test sites revealed a pronounced TG antigen reactivity and higher AA and MT values (mean and median). Upper jaw: control sites revealed a dislocation of AA in caudal direction, but also an improved vascularization in the peripheral wound area. While MT values (median) appeared to be comparable in both groups, AA, NMT, and NBM values (mean and median) tended to be higher at test sites.
It was concluded that (i) rhPDGF-BB soak-loaded on NBM might have the potential to support bone formation at chronic-type lateral ridge defects, and (ii) the application of CM did not seem to interfere with the factor activity, but ensured a stabilization of the graft particles.
To review the literature to assess the amount of change in height and width of the residual ridge after tooth extraction.
MEDLINE-PubMed and the Cochrane Central register of controlled trials (CENTRAL) were searched through up to March 2009. Appropriate studies which data reported concerning the dimensional changes in alveolar height and width after tooth extraction were included. Approximal height change, mid-buccal change, mid-crestal change, mid-lingual change, Alveolar width change and socket fill were selected as outcome variables. Mean values and if available standard deviations were extracted. Weighted mean changes were calculated.
Independent screening of the titles and abstracts of 1244 MEDLINE-PubMed and 106 Cochrane papers resulted in 12 publications that met the eligibility criteria. The reduction in width of the alveolar ridges was 3.87 mm. The mean clinical mid-buccal height loss was 1.67 mm. The mean crestal height change as assessed on the radiographs was 1.53 mm. Socket fill in height as measured relative to the original socket floor was on an average 2.57 mm.
During the post-extraction healing period, the weighted mean changes as based on the data derived from the individual selected studies show the clinical loss in width to be greater than the loss in height, assessed both clinically as well as radiographically.
'Bone: Formation by autoinduction', initiates by invocation of soluble molecular signals which, when combined to insoluble signals or substrata trigger the ripple-like cascade of bone differentiation by induction. The osteogenic proteins of the transforming growth factor-beta (TGF-beta) superfamily, the bone morphogenetic/osteogenic proteins (BMPs/OPs), and uniquely in the non-human primate Papio ursinus also the three mammalian TGF-beta isoforms, induce endochondral bone formation as recapitulation of embryonic development. The pleiotropic activities of the BMPs/OPs are vast and include the induction of periodontal tissue regeneration. Implantation of naturally derived highly purified osteogenic fractions after sequential adsorption/affinity and gel filtration chromatography in mandibular Class II furcation defects of P. ursinus induces cementogenesis as highly cellular collagenic cementoid attached to the exposed dentine with foci of nascent mineralization with inserted de novo generated Sharpey's fibres. Recombinant human osteogenic protein-1 (hOP-1) when implanted in Class II furcation defects of P. ursinus with surgically exposed dentine matrix preferentially initiates the induction of cementogenesis; on the other hand, hBMP-2 preferentially induces alveolar bone regeneration with mineralized bone covered by prominent osteoid seams. Long-term studies with gamma-irradiated 0.5 and 2.5mg hOP-1 per gram of xenogeneic bovine collagenous matrix induce the restitutio ad integrum of the periodontal tissues in furcation defects exposed by chronic periodontitis in P. ursinus. A challenging question for tissue engineering and regenerative medicine is whether the presence of molecularly different osteogenic proteins of the TGF-beta superfamily has a therapeutic significance. Mechanistically, the specificity of hOP-1 primarily initiating cementogenesis in periodontal defects is regulated by both the dentine extracellular matrix upon which responding cells attach and differentiate, and the structure/activity profile of the implanted hOP-1; the limited induction of cementogenesis by hBMP-2 in furcation defects of non-human primate and canine models is consistent with the reported data that hBMP-2 inhibits differentiation and mineralization of cementoblasts in vitro aside the specific structure/activity profile of the implanted hBMP-2 protein. The induction of periodontal tissue regeneration develops as a mosaic structure in which the osteogenic proteins of the TGF-beta superfamily singly, synergistically and synchronously initiate and maintain tissue induction and morphogenesis as a recapitulation of embryonic development.
Authors – Wikesjö UME, Qahash M, Huang Y‐H, Xiropaidis A, Polimeni G, Susin C
Surgical placement of endosseous oral implants is governed by the prosthetic design and by the morphology and quality of the alveolar bone. Nevertheless, often implant placement may be complexed, if at all possible, by alveolar ridge irregularities resulting from periodontal disease, and chronic and acute trauma. In consequence, implant positioning commonly necessitates bone augmentation procedures. One objective of our laboratory is to evaluate the biologic potential of bone morphogenetic proteins (BMP) and other candidate biologics, bone biomaterials, and devices for alveolar ridge augmentation and implant fixation using discriminating large animal models. This focused review illustrates the unique biologic potential, the clinical relevance and perspectives of recombinant human BMP‐2 (rhBMP‐2) using a variety of carrier technologies to induce local bone formation and implant osseointegration for inlay and onlay indications. Our studies demonstrate a clinically relevant potential of a purpose‐designed titanium porous oxide implant surface as stand‐alone technology to deliver rhBMP‐2 for alveolar augmentation. In perspective, merits and shortcomings of current treatment protocol including bone biomaterials and guided bone regeneration are addressed and explained. We demonstrate that rhBMP‐2 has unparalleled potential to augment alveolar bone, and support implant osseointegration and long‐term functional loading. Inclusion of rhBMP‐2 for alveolar augmentation and osseointegration will not only enhance predictability of existing clinical protocol but also radically change current treatment paradigms.
The use of platelet-rich plasma (PRP) in bone reconstruction therapy was introduced in the late 1990s. Since then, many scientists and clinicians have employed it in orthopaedic and oral surgeries. Unfortunately, studies that analyze the use of PRP are somewhat controversial as some conclude that the use of PRP may favor bone regeneration and others conclude that the use of PRP is irrelevant. By listing and analyzing the biological effect that each factor released by the activated platelets can have in bone regeneration, the present review answers the question of why PRP may be useful in bone reconstruction therapy. Subsequently, by examining the studies that have both successfully and unsuccessfully utilized PRP, it suggests how PRP might be used in order to achieve successful results in orthopaedic and dental bone reconstruction surgeries.
This study aimed to evaluate clinical outcomes of titanium membrane and compare these findings with clinical outcomes of e-PTFE membrane, and to investigate the effect of bacterial contamination on both membranes with SEM during long-term healing.
Sixteen titanium and sixteen e-PTFE membranes were surgically placed adjacent to periodontally involved teeth. Seven titanium and 8 e-PTFE membranes were exposed between 4 and 6 weeks. There were no significant difference between groups for plaque and gingival index. Probing depth and clinical attachment level (CAL) were decreased in both groups when compared with baseline; however, these differences were not statistically significant. The CAL gains between the groups were statistically different in 3rd, 6th, 9th, 12th, and 24th months (p < 0.05), and the CAL gain was significantly higher in titanium membrane (p < 0.05). There was significant decrease in bleeding on probing from baseline in both groups (p < 0.05). Surfaces of 15 membranes were studied using SEM. The largest amount of bacteria was found on the external cervical surfaces of 15 exposed specimens. The entire surface showed the presence of slough epithelial cells, leukocytes, red blood cells, yeast, and microbial plaque. Thirteen external mid surfaces of the 15 specimens, external apical surfaces of three e-PTFE and 1 titanium membrane, internal collar surfaces of all specimens, internal mid surfaces of 5 e-PTFE and three titanium membranes and internal apical surface of only one e-PTFE membrane were infected.
This study demonstrated that titanium membrane is equivalent to e-PTFE membranes for GTR in the treatment of periodontal defects.
Unlabelled:
Autotransplantation is the surgical repositioning of a tooth within the same patient. It can be thought of as a controlled avulsion and re-implantation of a tooth in a new, surgically prepared socket. The indications for its use are discussed, as too are factors affecting the success and the clinical procedures. The preservation and regeneration of the periodontal ligament is the key to success of this treatment. A case involving the transplantation of a premolar tooth into the central incisor location in a child is presented to show the different stages of the process.
Clinical relevance:
Autotransplantation is an underutilized technique which, when used within a multidisciplinary team, can offer an ideal treatment option for child or adolescent patients with missing or failing anterior teeth.
Sixteen intrabony defects in 12 patients were treated by gingival flap surgery including root surface debridement and placement of an expanded polytetrafluoroethylene (ePTFE) membrane. The membranes were removed after 4 to 6 weeks and examined by scanning electron microscopy (SEM) for bacterial contamination and adherent connective tissue elements. Twelve months postsurgery, the defect sites were reexamined for changes in probing attachment level and probing bone level. Comparison of ultrastructural findings and clinical observations revealed that extent of bacterial contamination of the membrane correlated inversely with clinical assessment of attachment gain. The results indicate that the extent of oral exposure and bacterial contamination of the ePTFE membrane at the time of removal may be an indicator of the long-term success or failure of the regenerative procedure.
Since 1985, the authors have been using madreporic coral fragments (genera Porites) as a bone graft substitute. Of the 167 coral grafts implanted, 150 were coral "corks" used to obliterate burr holes (diameter 10 mm), five were large implants (length 20 to 40 mm) to repair skull defects, and 12 were coral blocks to reconstruct the floor of the anterior cranial fossa. Previous experimental studies suggested that coral grafts would be well tolerated and become partially reossified as the calcific skeleton was resorbed. The authors describe their experience and detail the main biological properties of these materials, which appear to be very promising for use in cranial reconstructive surgery.
Cancellous and cortical autografts histologically have three differences: (1) cancellous grafts are revascularized more rapidly and completely than cortical grafts; (2) creeping substitution of cancellous bone initially involves an appositional bone formation phase, followed by a resorptive phase, whereas cortical grafts undergo a reverse creeping substitution process; (3) cancellous grafts tend to repair completely with time, whereas cortical grafts remain as admixtures of necrotic and viable bone. Physiologic skeletal metabolic factors influence the rate, amount, and completeness of bone repair and graft incorporation. The mechanical strengths of cancellous and cortical grafts are correlated with their respective repair processes: cancellous grafts tend to be strengthened first, whereas cortical grafts are weakened. Bone allografts are influenced by the same immunologic factors as other tissue grafts. Fresh bone allografts may be rejected by the host's immune system. The histoincompatibility antigens of bone allografts are presumably the proteins or glycoproteins on cell surfaces. The matrix proteins may or may not elicit graft rejection. The rejection of a bone allograft is considered to be a cellular rather than a humoral response, although the humoral component may play a part. The degree of the host response to an allograft may be related to the antigen concentration and total dose. The rejection of a bone allograft is histologically expressed by the disruption of vessels, an inflammatory process including lymphocytes, fibrous encapsulation, peripheral graft resorption, callus bridging, nonunions, and fatigue fractures.
Cores of bone from healing extraction sites were studied at time intervals of 4, 6, 8, 10, 12 and 16 weeks. The results revealed that between 4 and 8 weeks proliferation of cellular and connective tissue elements occur within the healing socket. Islands of new bone with an osteoid seam surrounded by osteoblasts are present within the connective tissue. From 8 to 12 weeks the bone undergoes maturation and forms a trabecular pattern. Although less pronounced, and osteoid seam is still present and osteoblasts occur in fewer numbers. By 12 to 16 weeks the bony trabeculae are mature with very little osteoid and few osteoblasts. This bone resembles alveolar trabecular bone. Two phases of bony regeneration are apparent from the present study. From 4 to 8 weeks there is a progressive osteogenic phase with proliferation of osteogenic cells and immature bone formation. From 8 to 12 weeks the osteogenesis slows down and the trabeculae mature and increase in volume. From 12 to 16 weeks the bone appears to stabilize with an established alveolar trabecular bone being present. Very little osteogenesis occurs as evidenced by minimal or no osteoid seam with only occasional osteoblasts. It is apparent that in the period between 8 and 12 weeks a substantial quantity of relatively mature well formed bone is present which contains osteoblasts and an osteoid seam. This appears to be an optimal time period to secure bone from a healing extraction site for grafting purposes.
Abstract The present experiment was undertaken to test the hypothesis that new connective tissue attachment may form on a previously periodontitis involved root surface provided cells originating from the periodontal ligament are enabled to repopulate the root surface during healing.
A mandibular incisor with advanced periodontal disease of long standing (the distance between the cemento-enamel junction and the alveolar bone crest was 9 mm) was subjected to periodontal surgery using a technique which during healing prevented the dentogingival epithelium and the gingival connective tissue from reaching contact with the curetted root surface. Preference was hereby given to the periodontal ligament cells to repopulate the previously diseased root surface. After 3 months of healing a block biopsy containing the incisor and surrounding tissue was sampled. The histological analysis revealed that new cementum with inserting principal fibers had formed on the previously diseased root surface. This new attachment extended in coronal direction to a level 5 mm coronal to the alveolar bone crest. This finding suggests that new attachment can be achieved by cells originating from the periodontal ligament and demonstrates that the concept that the periodontitis affected root surface is a major preventive factor for new attachment is invalid.
This study determined the microbiota of the mucosa- and implant-facing parts of expanded polytetrafluoro ethylene augmentation material, and the influence of major periodontopathogens on the healing process associated with guided bone regeneration around dental implants. Seventeen patients with nine dehiscence and eight extraction defects were studied. Prior to surgery and at membrane removal, microbial morphotypes, total viable counts, and the occurrence of selected microbial species were examined by phase-contrast microscopy, nonselective and selective cultures, and DNA probes. Nine sites with submerged barrier membranes throughout the 9-month study were free of cultivable microorganisms and experienced significantly more osseous healing than eight sites with prematurely exposed membrane. Patients with few or no deep periodontal pockets demonstrated significantly fewer residual osseous defects than patients showing several pockets of increased depths. In addition, patients with prematurely exposed membranes revealed several deep periodontal pockets. Three patients with less than 1 mm of osseous gain yielded either Porphyromonas gingivalis or Actinobacillus actinomycetemcomitans. Peptostreptococcus micros occurred in high proportions in seven of the eight patients with premature membrane exposure and inadequate osseous healing. These findings associate putative periodontal pathogens with unsuccessful guided bone regeneration. The control of periodontal pathogens in the oral cavity prior to placement of barrier membranes around implants might increase the prognosis of osseous regeneration.
The research reviewed in this paper constitutes a series of investigations intended to develop and evaluate a new membrane technique, which provides improved conditions for osteogenesis during healing of bone defects and restitution of earlier existing bone. The technique has also been shown to aid in bone grafting as well as having the capacity to create new bone for reconstructive purposes. According to this methodology, membranes are utilized to create a space in the tissue in which osteogenesis can occur relatively unimpeded. The paper provides a review of our initial animal experimental work as well as some clinical studies with special emphasis on membrane use in conjunction with dental implants. Possible mechanisms behind the efficacy of the membrane technique are reviewed, and future perspectives of development are also discussed. The osteopromotive membrane technique represents a principally new and major advance in bone biology and reconstructive skeletal surgery. Based on the results obtained by us and by others, the technique is presently utilized clinically in some routine applications.
In 51 patients (21 males and 30 females) aged 16 to 72 years, a total of 109 Nobelpharma implants were placed into extraction sockets immediately following extraction. The follow-up period varied between 1 and 67 months with a mean of 30.5 months. Osseointegration was determined by clinical stability, lack of symptoms, and lack of peri-implant pathology based on radiographic examination. The implant survival rate was 93.6%. Six implants were mobile at the abutment connection stage, and one was lost when function commenced. The success rate was 92.0% for implants replacing teeth extracted because of periodontitis and 95.8% for implants replacing teeth extracted for other reasons. Two other complications occurred: 12 cover screws perforated the gingiva during healing; and infection developed in five cases. The incidence of infection was higher in the periodontitis group. It was found that immediate placement of implants into extraction sockets is a safe and predictable procedure if certain guidelines are followed.
Our goal in this study was to evaluate the effects of and the interaction between the hypothesized principal determinants of the incorporation of grafts: antigenicity and treatment of the graft. We implanted fresh and frozen cortical bone grafts that were matched for both major and non-major histocompatibility complex antigens (syngeneic grafts), matched for major but not for non-major histocompatibility complex antigens (minor mismatch), and mismatched for both major and non-major histocompatibility complex antigens (major mismatch). We used a rat model with an eight-millimeter segmental defect in the femur. The construct was stabilized with a plastic plate, threaded Kirschner wires, and cerclage wires. We evaluated the grafts at one, two, and four months after implantation. We measured the immune response; assessed the incorporation of the graft with use of histological examination, biomechanical testing, and quantitative isotopic kinetics; and statistically analyzed the effects of and the interactions among three independent variables: time, the degree of matching for major histocompatibility complex antigens, and the treatment of the graft (whether it was fresh or frozen). These three independent variables had profound effects on the pattern, rate, and quality of the incorporation of the graft. Two-way and three-way interactions among these variables were also noted. Serial changes in every dependent variable were observed with time. Systemic antibody specific for donor antigens was measurable only in the serum of animals that had a major mismatch, but freezing markedly attenuated the systemic antibody response. Revascularization was profoundly affected by histocompatibility-antigen matching; the syngeneic grafts were revascularized more quickly and to a greater degree than the grafts with either a minor or a major mismatch. Freezing significantly (p < 0.001) reduced the revascularization of the syngeneic grafts but had no discernible effect on the grafts with a minor mismatch.
This article reviews the current understanding of the biology of tooth extraction wound healing and residual ridge remodeling.
The review of the biology of tooth extraction wound healing involves a discussion of the different cells populating the tooth extraction wound, the matrix formation, and the control of the repair process in the short-term. Defects in socket matrix formation or cellular activity will lead to stalled healing. The review of residual ridge remodeling describes the long-term result of tooth extraction and formation of residual ridges, in which the quantity of bone tissue continuously decreases. This may suggest that any potential regulatory factors of residual ridge resorption should have an adverse effect either on the increased catabolic activity by osteoclasts or on the decreased anabolic activity by osteoblasts. Both short-term tooth extraction healing and long-term residual ridge remodeling processes are interdependent. Furthermore, any potential genetic and environmental regulatory factors can affect the quality and quantity of bone by altering the gene expression events taking place in bone cells.
The intent of this article was to review the current progresses of biologic research on residual ridge remodeling and to relate the changes at molecular, cellular, and tissue levels. The understanding of residual ridge remodeling may provide a sound scientific basis for improved restorative and therapeutic treatments of the edentulous population.
The uncertainties about the transmission of prion proteins from xenogenic grafts prepared from bovine bone has led to the reconsideration of allogenic bone as a grafting material. Allografting is a complementary technique to autografting nowadays when large bone volumes are necessary. Several preparation techniques have been proposed. Fresh-frozen, freeze-dried and gamma irradiation are the most common. However, a large amount of lipids is present in the medullary spaces (near 70% in weight for a human femoral head). They are known to strongly influence the biocompatibility of the bone graft. The exact changes of lipids upon the sterilization and storage processes are poorly known. The aims of the present study were to appreciate the effects of gamma irradiation on medullary lipids and to identify the cytotoxicity of gamma-irradiated bank bone with/without lipid on cultures of osteoblast-like cells. Bone cores from 8 femoral heads retrieved during prosthesis surgery for arthritis were prepared with a drilling trephine. Cores were either sterilized by gamma radiations (25000 gray) or kept frozen until lipid extraction and lipofuschine-like dosage by Folch's method and fluorometric study. Peroxidated lipids appeared 2 to 3-fold higher in the gamma-irradiated cores than in frozen ones. Slices were prepared from bone cores and were transferred on confluent osteoblast-like cell layers (Saos-2). The raw slices (containing lipids) did not induce cell death. On the other hand, cell death was dramatically increased around the gamma-irradiated slices. Defatted slices which had been sterilized by gamma radiations or UV did not induce cell death. Defatting procedures should be added when preparing bone allografts in human bone banks.
Different types of biodegradable membranes have become available for guided tissue regeneration. The purpose of this study was to evaluate histologically three different biodegradable membranes (Bio-Gide, Resolut and Vicryl) and one non-biodegradable membrane (expanded polytetrafluoroethylene/e-PTFE) implanted subcutaneously in rats. Five subcutaneous pouches were created in each of 24 rats. One of the four test membranes was randomly placed in each of the four pouches and one pouch was left empty to serve as a control. Histological evaluation was performed after 4, 10 and 21 days which demonstrated that e-PTFE was well tolerated and encapsulated by a fibrous connective tissue capsule. There was capsule formation around Resolut and Vicryl and around Bio-Gide in the early phase there was a wide inflammatory zone already. e-PTFE and Vicryl were stable materials while Resolut and Bio-Gide fragmented in the early phase. In the late phase Vicryl was surrounded by an increasing amount of multinucleated macrophages and a thin capsule, whilst around Resolut and Bio-Gide a strong foreign body reaction was observed. Also granuloma formation was noted around the fragmented Resolut material in its capsule and a mild inflammatory reaction surrounding Bio-Gide within its thin capsule.
Guided bone regeneration (GBR) is employed to encourage the formation of new bone in osseous defects by restricting the infiltration of soft tissues. While a variety of membranes have been evaluated for this surgical procedure, the non-resorbable material of choice is currently expanded polytetrafluoroethylene (e-PTFE). A new alkali-cellulose membrane produced by a biotechnological process has been developed as an alternative to e-PTFE for GBR. In this study, the biocompatibility of this novel alkali-cellulose membrane and e-PTFE was compared using tissue culture and an in vivo GBR model. In vitro both materials supported the attachment, migration and differentiation of osteoblast-like cells in culture for up to 3 weeks. The in vivo model was based upon full-thickness transcortical bone defects in the mandibular rami of Sprague-Dawley rats. The right rami were used as controls, contralateral defects being covered bucally and lingually with either e-PTFE or alkali-cellulose membranes. Pathological and histomorphometric analysis was undertaken at 4 and 10 weeks post-implantation. Bone regeneration associated with alkali-cellulose membranes was predominantly endochondral in type in contrast to e-PTFE which induced direct bone formation (intramembranous ossification). The amount of new bone formed in defects was similar for both types of membrane, but alkali-cellulose membranes induced significantly greater inflammatory response; characterized by lymphocytes, macrophages and multinucleated giant cells. Degradation and possible exposure of individual cellulose fibres may account for the poor performance of alkali-cellulose membranes in vivo. This animal and in vitro study indicates that when choosing a non-resorbable membrane for GBR, e-PTFE membranes are likely to perform better than those produced from alkali-cellulose.
Because of the limited observations of published studies, the condition of hydroxyapatite after a long period of intraoral function remains a concern. This clinical report describes the histologic evaluation of a 9 year-old hydroxyapatite specimen retrieved from a human subject. The residual hydroxyapatite particles showed no sign of resorption, and tight contact with the surrounding bone was observed.
Bone loss after tooth extraction may prevent dental implant placement. Human mineralized bone grafts can be used to restore bone volume and allow for tooth replacement with dental implants.
The authors grafted 22 sites in 18 patients with human mineralized bone after tooth extraction. They allowed molar sites 16 weeks for graft healing, placed the implants and restored them with a final crown after a four-month integration period. Single-rooted maxillary sites received implants and immediate placement of provisional crowns or underwent a delayed two-stage restoration approach. The authors used radiographs and clinical examinations to evaluate the results.
All of the sites were restored successfully with a single-tooth implant restoration. Periapical radiographs indicated that the crestal bone levels were limited to the first thread of the implants or slightly coronal to the first thread of the implant. Clinical evaluation indicated excellent gingival health around the provisional and final restorations, without obvious gingival migration.
The use of human mineralized bone may have significant potential to reconstruct missing bone resulting from tooth extraction and to preserve bone after tooth extraction. In addition, healed bone graft sites seem to be able to support immediate placement of a provisional crown and implant restorations.
Patients who are having teeth extracted may become candidates for implant restorations when the sites are appropriately grafted to preserve and reconstruct bone volume, thus allowing for more options for reconstructing the missing tooth site.
Successful bone augmentation requires predictable space maintenance and adequate exclusion of those cells that lack osteogenetic potential from the defect area. Natural bone mineral is considered to be osteoconductive and is used as space maker in combination with membrane barrier techniques. The aim of this study was to compare qualitative histological results achieved by using deproteinized bovine bone mineral (DBBM) as a space maintainer and a new collagen barrier (Ossix, test group) vs. the same bone substitute and the standard e-PTFE membrane (Gore-Tex), control group). Twenty-eight patients were randomly assigned to the test or the control group. Seven months after augmentation procedures, biopsies were obtained at reentry and were analysed histomorphometrically. In all, 14 specimens of group I (test group, Ossix) and 13 specimens of group II (controls, PTFE-membranes) showed close qualitative similarity of their histologies. Histomorphometrically, total mineralized bone area was 42% +/- 18% in group I vs. 39% +/- 15% in group II. The unmineralized tissue area was 44% +/- 15% vs. 46% +/- 12% and the area of DBBM remnants 14% +/- 9% and 15% +/- 12%, respectively. The differences were statistically nonsignificant (Mann-Whitney test). The occurrence of barrier exposure did not interfere with the histological outcome either in the test or in the control group. The new collagen barrier combined with the DBBM provided qualitative bone regeneration comparable to the standard e-PTFE material combined with the same mineral.
It has already been shown that occlusive titanium barriers have osteoconductive properties. These barriers, however, cover only a limited surface area and have only been used in animal experiments. The aim of this study was to evaluate bone neogenesis under a pre-shaped titanium barrier placed over the top of the rabbit skull and the top of highly resorbed edentulous upper-jaw bone in patients. Computed tomography (CT) scans made it possible to pre-shape the titanium barrier according to individual bone shape in human experiments. On the rabbit skull, tissue augmentation of up to 6 mm 1 year after barrier placement was observed, while the original thickness of skull bone was on average between 1.5 and 2.5 mm. The bone, which remained histologically immature for 1 year, grew systematically along the titanium surface, illustrating its osteoconductivity. Even after removal of the barrier, on average, 75.3 and 59.4% of the newly created tissue volume was maintained after 3 and 9 months, respectively. Clinical observations on 10 consecutive patients showed that, in those (5/10) in which the barrier remained unexposed for several months, an increase of the jawbone height and width of up to 16 mm could be observed when the barrier was removed after 12-18 months. As in the rabbits at barrier removal, the bone demonstrated a limited degree of mineralization as ascertained from biopsies. This newly formed osteoid tissue allowed the insertion of 33 screw-shaped titanium implants which in most cases (30/33) successfully osseointegrated to support a fixed prosthesis. The surrounding marginal bone level remained stable even up to 5 years after implant placement. Both animal and clinical data demonstrate that guided bone neogenesis under a subperiosteally placed titanium barrier can reach large volumes.
The purpose of this study was to evaluate the use of mineralized freeze-dried bone allograft (FDBA) in conjunction with a titanium-reinforced expanded polytetrafluoroethylene (TR e-PTFE) barrier in the treatment of localized alveolar ridge deficiencies prior to endosseous dental implant placement. Twelve patients (aged 23 to 65 years) requiring tooth replacement with ridge augmentation were recruited to participate in this study. During ridge augmentation surgery, measurements were made prior to grafting with FDBA plus a TR e-PTFE barrier. Six months later, ridge measurements were repeated, and suitability for implant placement was assessed. At each implant site, a biopsy was taken from the grafted site. The implants were placed and allowed to osseointegrate for 13 weeks prior to phase-two surgery. Clinical data analyzed were horizontal ridge width changes and vertical ridge height changes. Histologic evaluation revealed the formation of new bone and residual particles in each graft site at the time of implant placement Ten patients completed the study. The mean alveolar ridge width increased by 3.2 +/- 1.0 mm (P < .0005). Histomorphometric analysis revealed a range of new bone from 42.9% to 70.5%, with a mean of 47.6%. Graft particles remaining ranged from 29.5% to 57.1%, with a mean of 52.4%. The clinical and histologic findings of this study demonstrate that sites grafted with FDBA in conjunction with an e-PTFE barrier can provide a predictable way to augment deficient alveolar ridges prior to implant placement.
The placement of different graft materials and/or the use of occlusive membranes to cover the extraction socket entrance are techniques aimed at preserving/reducing alveolar ridge resorption. The use of grafting materials in fresh extraction sockets has, however, been questioned because particles of the grafted material have been found in alveolar sockets 6-9 months following their insertion.
The aims of the study were to (i). evaluate whether alveolar ridge resorption following tooth extraction could be prevented or reduced by the application of a bioabsorbable polylactide-polyglycolide sponge used as a space filler, compared to natural healing by clot formation, and (ii). evaluate histologically the amount and quality of bone tissue formed in the sockets, 6 months after the use of the bioabsorbable material.
Thirty-six patients, undergoing periodontal therapy, participated in this study. All patients were scheduled for extraction of one or more compromised teeth. Following elevation of full-thickness flaps and extraction of teeth, measurements were taken to evaluate the distance between three landmarks (mesio-buccal, mid-buccal, disto-buccal) on individually prefabricated stents, and the alveolar crest. Twenty-six alveolar sockets (test) were filled with a bioabsorbable polylactide-polyglycolide acid sponge (Fisiograft), while 13 sockets (controls) were allowed to heal without any filling material. The flaps were sutured with no attempt to achieve primary closure of the surgical wound. Re-entry for implant surgery was performed 6 months following the extractions. Thirteen biopsies (10 test and three control sites) were harvested from the sites scheduled for implant placement.
The clinical measurements at 6 months revealed, in the mesial-buccal site, a loss of bone height of 0.2 mm (1.4 SD) in the test and 0.6 mm (1.1 SD) in the controls; in the mid-buccal portion a gain of 1.3 mm (1.9 SD) in the test and a loss of 0.8 mm (1.6 SD) in the controls; and in the distal portion a loss of 0.1 mm (1.1 SD) in the test and of 0.8 (1.5 SD) mm in the controls. The biopsies harvested from the test sites revealed that the new bone formed at 6 months was mineralized, mature and well structured. Particles of the grafted material could not be identified in any of the 10 test biopsies. The bone formed in the control sites was also mature and well structured.
The results of this study indicate that alveolar bone resorption following tooth extraction may be prevented or reduced by the use of a bioabsorbable synthetic sponge of polylactide-polyglycolide acid. The quality of bone formed seemed to be optimal for dental implant insertion.
Premature exposure of membranes used in guided bone regeneration (GBR) results in decreased bone formation. The effect of an expanded polytetrafluoroethylene (e-PTFE) and two collagen membrane on bone healing of buccal dehiscence defects around implants in cases with and without premature membrane exposure was clinically evaluated.
Three groups were established: Group OS (Ossix, n=73 implants, 41 patients), Group BG (Bio-Gide, n=53 implants, 28 patients) and Group GT (e-PTFE, Gore-Tex, n=34 implants, 17 patients). Defect height and width were measured at the time of implant placement and at second stage surgery. Surface area was calculated as half ellipses. When several implants were placed simultaneously, a mean of their defect width and height was calculated.
Mean percentage reduction of defect area (92.2+/-13.78% Group OS, 94.6+/-6.69% Group BG, and 97.3+/-4.91% Group GT) and height (81.6+/-23.19%, 85.4+/-12.26%, and 93.4+/-9.39% respectively) did not show statistically significant differences between groups. Differences between groups were not statistically significant for all parameters when cases without spontaneous membrane exposure were compared. However, differences were significant when spontaneous membrane exposure occurred. Mean percentage reduction of defect area among cases where membrane exposure occurred was 91.5+/-10.86% Group OS, 71.5+/-8.61% Group BG, and 73.7+/-13.97% Group GT. Mean percentage reduction of defect height among cases with membrane exposure was 76.4+/-18.28%, 53.4+/-9.86%, and 49.4+/-11.05%, respectively.
Premature exposure of membranes and subsequent and consequent exposure of implants results in impaired bone healing. Certain barrier membranes, as used in group OS, are apparently capable of supporting gingival healing even when prematurely exposed that could be advantageous in GBR procedures.
The aim of the present study was to evaluate the clinical performance of a regenerative strategy for the treatment of deep intrabony defects.
This patient cohort study involved 40 patients with one deep interdental intrabony defect each. They were treated with periodontal regeneration using four different regenerative methods (expanded polytetrafluoroethylene [ePTFE] titanium reinforced membranes, bioabsorbable membranes alone, bioabsorbable membranes with a bone replacement graft [combination], or enamel matrix derivative), according to predefined criteria and decision-making algorithms. Defects were accessed with papilla preservation flaps performed with the aid of an operating microscope and microsurgical instruments. A stringent plaque control regimen was enforced in all the patients during the 1-year observation period. Outcomes included evaluation of the complete primary closure of the interdental space (CLOSURE), gains in clinical attachment (CAL), and reductions in probing depths (PD).
CLOSURE was achieved in all treated defects and was maintained in 90% of cases for the entire healing period. At 1 year the observed CAL gains were 6 +/- 1.8 mm on average, corresponding to a resolution of 92.1% +/- 12% of the initial intrabony (CAL%) component of the defect. Average PD reduction was 6.1 +/- 1.9 mm and was associated with minimal increase in gingival recession (-0.1 +/- 0.7 mm). The 12 sites treated with titanium reinforced ePTFE membranes resulted in a 1-year CAL gain of 6.8 +/- 2.2 mm (CAL%: 94.7 +/- 13.4); the 11 cases treated with combination therapy showed a 1-year CAL gain of 5.4 +/- 1.7 mm (CAL%: 88.2 +/- 9.6); the seven sites treated with bioabsorbable barriers resulted in 5.9 +/- 1.2 mm of CAL gain (CAL%: 88.9 +/- 11.5); and the 10 sites treated with enamel matrix gained on average 5.9 +/- 1.5 mm of CAL (CAL%: 88.9 +/- 11.5). No significant differences were observed among the four approaches.
The use of an evidence-based regenerative strategy resulted in clinically relevant amounts of CAL gains, shallow pockets, and minimal gingival recession with the four regenerative approaches.
The purpose of this study was to histologically analyze the influence of bioactive glass and/or a calcium sulfate barrier on bone healing in surgically created defects in rat tibias.
Sixty-four rats were divided into 4 groups: C (control), CS (calcium sulfate), BG (bioactive glass), and BG/CS (bioactive glass/calcium sulfate). A surgical defect was created in the tibia of each animal. In Group CS, a calcium sulfate barrier was placed to cover the defect. In Group BG the defect was filled with bioactive glass. In Group BG/CS, it was filled with bioactive glass and protected by a barrier of calcium sulfate. Animals were sacrificed at 10 or 30 days post-operative. The formation of new bone in the cortical area of the defect was evaluated histomorphometrically.
At 10 days post-operative, Group C presented significantly more bone formation than Groups CS, BG, or BG/CS. No statistically significant differences were found between the experimental groups. At 30 days post-operative, Group C demonstrated significantly more bone formation than the experimental groups. Groups CS and BG/CS showed significantly more bone formation than Group BG. No statistically significant differences were found between Group CS and BG/CS.
(a) the control groups had significantly more bone formation than the experimental groups; (b) at 10 days post-operative, no significant differences were found between any of the experimental groups; and (c) at 30 days post-operative, the groups with a calcium sulfate barrier had significantly more bone formation than the group that used bioactive glass only.
To determine clinical success when implants are placed in chronic periapical infected sites.
Fifty patients (25 females, 25 males, mean age 39.7 +/- 14.5 years) were included in this prospective controlled study. After randomization, 25 Frialit-2 Synchro implants were immediately placed (IP) after extraction, and 25 Frialit-2 Synchro implants were placed after a 3-month healing period (DP). Thirty-two implants were placed in the anterior maxilla and 18 implants were placed in the premolar region. Implant survival, mean Implant Stability Quotient (ISQ) values, gingival aesthetics, radiographic bone loss, and microbiologic characteristics of periapical lesions were evaluated for both groups.
Overall, 2 implants belonging to the IP group were lost, resulting in a survival rate of 92% for IP implants versus 100% for DP implants. Mean ISQ, gingival aesthetics and radiographic bone resorption, and periapical cultures were not significantly different with the IP and DP implants.
Immediate implant placement in chronic periapical lesions may be indicated.