Acellular dermal matrix and hydroxyapatite in prevention of ridge deformities after tooth extraction

Simultaneous Implant and Guided Bone Regeneration Using Bovine-Derived Xenograft and Acellular Dermal Matrix in Aesthetic Zone

INTRODUCTION

Implant placement in the maxillary anterior area requires sufficient quantity and quality of both soft and hard tissue. In cases where soft and hard tissues are insufficient, additional regeneration using biomaterials is recommended. Treatment using bovine-derived xenograft and acellular dermal matrix (ADM) may increase bone volume and soft tissue thickness. Case and management: A 65-year-old woman sought help for discomfort and aesthetic issues with her denture, reporting missing teeth (11, 12, 13, 14, and 21) and bone volume shrinkage due to disuse atrophy. Intraoral examination revealed 1 mm gingival thickness. CBCT showed labio-palatal bone thickness of 6.0 mm, 5.8 mm, and 4.7 mm for teeth 21, 12 and 14, respectively. Implant planning and surgical guide fabrication were carried out before the surgery. Surgery included the placement of implants 3.3 mm in diameter and 12 mm in length, with the use of xenograft and ADM. Three months post-op, improvements in soft and hard tissues were observed, with a final prosthesis being a long-span implant-supported bridge.

CONCLUSIONS

Disuse alveolar atrophy causes soft and hard tissue deficiency. The use of xenograft and ADM show favourable results even on a geriatric patient.

Bone Grafts and Substitutes in Dentistry: A Review of Current Trends and Developments

After tooth loss, bone resorption is irreversible, leaving the area without adequate bone volume for successful implant treatment. Bone grafting is the only solution to reverse dental bone loss and is a well-accepted procedure required in one in every four dental implants. Research and development in materials, design and fabrication technologies have expanded over the years to achieve successful and long-lasting dental implants for tooth substitution. This review will critically present the various dental bone graft and substitute materials that have been used to achieve a successful dental implant. The article also reviews the properties of dental bone grafts and various dental bone substitutes that have been studied or are currently available commercially. The various classifications of bone grafts and substitutes, including natural and synthetic materials, are critically presented, and available commercial products in each category are discussed. Different bone substitute materials, including metals, ceramics, polymers, or their combinations, and their chemical, physical, and biocompatibility properties are explored. Limitations of the available materials are presented, and areas which require further research and development are highlighted. Tissue engineering hybrid constructions with enhanced bone regeneration ability, such as cell-based or growth factor-based bone substitutes, are discussed as an emerging area of development.

The Impact of Double Layer Membrane Technique on Bone Regeneration in Postextraction Alveoli – A Pathohistological Experimental Study in Dogs

Post extraction alveolar ridge preservation is a preventive oral surgical procedure aimed to preserve the dimensions of the alveolar ridge after removal of the teeth. According to literature data, the utilization of guided bone regeneration for this purpose is absolutely justified. The aim of this study was to examine the effect of resorbable collagen membranes placed in two layers in respect to the application of membranes placed in one layer to the degree of bone regeneration after a tooth extraction. This experimental study was conducted on six adult dogs. In the first phase all four premolars were extracted on both sides in the lower jaw. After the volume-standardisation with bone drill, three post extraction alveoli were filled with bone substitute of equine origin and then covered with: collagen bioresor bable membrane of porcine origin; collagen bioresorbable membrane of equine origin; pericardial bioresorbable membrane of equine origin. The membranes on the left side were placed in single-layer and on the right side in double-layer manner. After different monitoring periods, histopathological analysis of the samples taken from the experimental regions was performed. A different degree of bone regeneration was achieved between experimental regions in which membranes were placed in one layer and those where membranes were placed in two layers. There was no difference between regions where membranes of different origin were placed in the same manner. The procedure of covering the post extraction alveoli, filled with bone substitute and with resorbable membranes placed in two layers resulted in a higher degree of bone regeneration compared to those where resorbable membranes were placed in one layer.

Extraction socket preservation

Extraction socket preservation (ESP) is widely performed after tooth extraction for future implant placement. For successful outcome of implants after extractions, clinicians should be acquainted with the principles and indications of ESP. It is recommended that ESP be actively implemented in cases of esthetic areas, severe bone defects, and delayed implant placement. Dental implant placement is recommended at least 4 months after ESP.

Barrier membranes: More than the barrier effect?

AIM

To review the knowledge on the mechanisms controlling membrane-host interactions in guided bone regeneration (GBR) and investigate the possible role of GBR membranes as bioactive compartments in addition to their established role as barriers.

MATERIALS AND METHODS

A narrative review was utilized based on in vitro, in vivo and available clinical studies on the cellular and molecular mechanisms underlying GBR and the possible bioactive role of membranes.

RESULTS

Emerging data demonstrate that the membrane contributes bioactively to the regeneration of underlying defects. The cellular and molecular activities in the membrane are intimately linked to the promoted bone regeneration in the underlying defect. Along with the native bioactivity of GBR membranes, incorporating growth factors and cells in membranes or with graft materials may augment the regenerative processes in underlying defects.

CONCLUSION

In parallel with its barrier function, the membrane plays an active role in hosting and modulating the molecular activities of the membrane-associated cells during GBR. The biological events in the membrane are linked to the bone regenerative and remodelling processes in the underlying defect. Furthermore, the bone-promoting environments in the two compartments can likely be boosted by strategies targeting both material aspects of the membrane and host tissue responses.

Composite Alloplastic Biomaterial vs. Autologous Platelet-Rich Fibrin in Ridge Preservation

AIM

The aim of this study was to examine the clinical and histological differences of using a combination of alloplastic beta triphasic calcium phosphate (β-TCP) and a cross-linked collagen membrane versus autologous platelet-rich fibrin (PRF-L) in ridge preservation after dental extraction.

MATERIAL AND METHODS

Fifty-one patients were included in this observational case-series study. Dental extractions were performed, after which 25 patients were grafted with β-TCP and 26 with PRF-L. After four months of healing, clinical, radiological, histomorphometric and histological evaluations were performed.

RESULTS

A significantly higher percentage of mineralized tissue was observed in samples from the PRF-L grafted areas. Cellularity was higher in PRF-L grafted areas (osteocytes in newly formed bone per mm² = 123.25 (5.12) vs. 84.02 (26.53) for PRF-L and β-TCP, respectively, p = 0.01). However, sockets grafted with PRF-L showed a higher reduction in the bucco-lingual dimension after four months of healing (2.19 (0.80) vs. 1.16 (0.55) mm, p < 0.001), as well as a higher alteration in the final position of the mid muco-gingival junction (1.73 (1.34) vs. 0.88 (0.88) mm, p < 0.01).

CONCLUSION

PRF-L concentrate accelerates wound healing in post-extraction sockets in terms of new mineralized tissue component. However, the use of β-TCP biomaterial appears to be superior to maintain bucco-lingual volume and the final position of the muco-gingival junction.

Synthetic polymeric barrier membrane associated with blood coagulum, human allograft, or bovine bone substitute for ridge preservation: a randomized, controlled, clinical and histological trial

During the normal healing process, an extraction site may lose significant bone volume, making implant placement problematic. Quantitative evaluations of the amount of bone maintained by socket preservation with various materials are limited. The objective of this study was to evaluate, both clinically and histologically, the extent of alveolar bone preservation by blood coagulum (BC) and the potential additional benefits of bone allograft material (AL) versus the state-of-the-art bovine bone mineral (BB), covered by a polyethylene glycol (PEG) barrier, in extraction socket grafting procedures. Adult patients (n=32) with single-rooted teeth indicated for extraction were treated (45 sites). After atraumatic extraction, the sockets were filled with BC, AL, or BB and covered with a synthetic PEG barrier membrane. Changes in bone height and width were measured clinically and the amount of bone formed and residual graft particles were measured histologically after 6 months. Changes in ridge width at 6 months were -1.5mm for AL versus -2.5mm for BB and -2.3mm for BC. New bone formation amounted to 47.8%, 33.3%, and 28.2% at BC-, AL-, and BB-treated sites, respectively. Using AL with the PEG barrier preserved the ridge width at 6 months better than BB or BC and resulted in similar amounts of bone histologically to BB.

The use of hydroxyapatite bone substitute grafting for alveolar ridge preservation, sinus augmentation, and periodontal bone defect: A systematic review

OBJECTIVES

We determined and structurally analyzed the reported effect of hydroxyapatite (HA) bone substitute on alveolar bone regeneration. To the best of our knowledge, no systematic reviews have previously reported the bone regenerative effect of the HA bone substitute.

MATERIALS AND METHODS

A literature search was performed for articles published up to August 2015 using MEDLINE with the search terms "hydroxyapatite," "bone regeneration," and "alveolar bone" as well as their known synonyms. The inclusion criteria were set up for human trials with at least five patients. The literature search, eligible article selection, and data extraction were independently performed by two readers, and their agreement was reported by κ value.

RESULTS

Of the 504 studies found using the MEDLINE literature search, 241 were included for further steps (inter-reader agreement, κ = 0.968). Abstract screening yielded 74 studies (κ = 0.910), with 42 completely fulfilling the inclusion criteria (κ = 0.864). In a final step, 42 studies were further analyzed, with 17 and 25 studies with and without statistical analysis, respectively. The 17 studies reporting similar outcome measures were compared using the calculated 95% confidence intervals. The effect of HA on ridge preservation could not be evaluated.

CONCLUSIONS

The use of the HA bone substitute interfered with the normal healing process, with significant differences found for sinus augmentation but not for periodontal bone defects. Thus, a bone substitute with optimal bone regenerative properties for alveolar ridge or socket preservation, sinus augmentation, and periodontal bony defect should be developed.

Pure type-1 collagen application to third molar extraction socket reduces postoperative pain score and duration and promotes socket bone healing

BACKGROUND/PURPOSE

Extraction of the third molar may cause post-operative complications. This study assessed whether application of pure type-1 collagen to the third molar extraction socket can reduce post-operative pain score and duration and promote socket bone healing.

METHODS

Fourteen patients who underwent 20 bilateral and symmetric third molar extractions were included in this study. After two tooth extractions at two different occasions in the same patient, one socket was filled with pure type-1 collagen (experimental group, n = 20) and the other socket received nothing but the blood clot (control group, n = 20). The post-operative pain score and duration, mouth-opening limitation, and the bone density at the socket site were assessed at weeks 1, 2, 4, and 8 after tooth extraction.

RESULTS

Patients in the experimental group had a significantly lower mean post-operative pain score (2.6 ± 1.2) than patients in the control group (4.7 ± 2.0), and had a significantly shorter post-operative pain duration (2.7 ± 1.4 days) than patients in the control group (3.7 ± 1.8 days). We also observed a significantly lower frequency of mouth-opening limitation in 20 experimental-group patients (45%) than in 20 control-group patients (90%, P = 0.007). Moreover, a significantly higher mineralization ratio (10.2%) was found in the experimental socket site than in the control socket site.

CONCLUSION

Application of pure type-1 collagen to the third molar extraction socket can reduce post-operative pain score and duration, decrease the frequency of mouth-opening limitation, and increase mineralization ratio at the extraction socket site.

Application of an acellular dermal matrix to a rabbit model of oral mucosal defects

Acellular dermal matrices (ADMs) are increasingly used for the restoration of soft-tissue defects of the oral cavity due to their ability to facilitate faster healing and reduce scar formation without rejection. However, few studies have focused on the histopathology and biological mechanisms involved in their use. The aim of the present study was to observe tissue growth, histopathologic changes and altered biomolecular signatures that occur during the repair of oral defects in rabbit models over time, either with or without the employment of ADM. Animals were sacrificed 1, 2 and 4 weeks following surgery and histological changes were evaluated using hematoxylin and eosin staining. Reverse transcription-polymerase chain reaction and western blot analysis were used to determine changes in the expression of vascular endothelial growth factor (VEGF) and glucose transporter 1 (GLUT1). It was demonstrated that wounds treated with ADM exhibited a weak inflammatory reaction and faster epithelialization and revascularization compared with untreated wounds. This may have been caused by the elevated levels of VEGF and GLUT1 protein detected in the ADM-treated defects. Thus, treating wounds of the oral mucosa with an ADM improves pathological responses compared with those with an untreated wound. The current study demonstrates the underlying mechanisms by which ADM promotes wound healing in defects of the oral mucosa and the results provide further evidence for the use of ADM in clinical settings for the repair of mucosal defects.

Guided bone regeneration: materials and biological mechanisms revisited

Guided bone regeneration (GBR) is commonly used in combination with the installment of titanium implants. The application of a membrane to exclude non‐osteogenic tissues from interfering with bone regeneration is a key principle of GBR. Membrane materials possess a number of properties which are amenable to modification. A large number of membranes have been introduced for experimental and clinical verification. This prompts the need for an update on membrane properties and the biological outcomes, as well as a critical assessment of the biological mechanisms governing bone regeneration in defects covered by membranes. The relevant literature for this narrative review was assessed after a MEDLINE/PubMed database search. Experimental data suggest that different modifications of the physicochemical and mechanical properties of membranes may promote bone regeneration. Nevertheless, the precise role of membrane porosities for the barrier function of GBR membranes still awaits elucidation. Novel experimental findings also suggest an active role of the membrane compartment per se in promoting the regenerative processes in the underlying defect during GBR, instead of being purely a passive barrier. The optimization of membrane materials by systematically addressing both the barrier and the bioactive properties is an important strategy in this field of research.

Alveolar socket healing: what can we learn?

Tooth extraction induces a series of complex and integrated local changes within the investing hard and soft tissues. These local alterations arise in order to close the socket wound and to restore tissue homeostasis, and are referred to as '"socket healing". The aims of the present report were twofold: first, to describe the socket-healing process; and, second, to discuss what can be learned from the temporal sequence of healing events, in order to improve treatment outcomes. The socket-healing process may be divided into three sequential, and frequently overlapping, phases: inflammatory; proliferative; and modeling/remodeling. Several clinical and experimental studies have demonstrated that the socket-healing process promotes up to 50% reduction of the original ridge width, greater bone resorption at the buccal aspect than at the lingual/palatal counterpart and a larger amount of alveolar bone reduction in the molar region. In conclusion, tooth extraction, once a simple and straightforward surgical procedure, should be performed in the knowledge that ridge reduction will follow and that further clinical steps should be considered to compensate for this, when considering future options for tooth replacement.

Histomorphometric results in ridge preservation procedures comparing various graft materials in extraction sockets with nongrafted sockets in humans: a systematic review

INTRODUCTION

The aim of this systematic review was to evaluate, from a histological point of view, the amount of newly formed bone in ridge preservation procedures using various graft materials in comparison with natural healing (NH) and to determine which is the ideal type of graft to be used.

MATERIALS AND METHODS

A search strategy was developed to find articles in a human model published between 1990 and January 2013 in English language using MEDLINE database.

RESULTS

Thirty-four articles were included in this systematic review. When comparing the percentage of newly formed bone using various grafting materials with NH, calcium sulfate, magnesium enriched hydroxyapatite, and porcine-derived bone grafts offered the best outcomes. However, due to the heterogeneity of the included studies, the search was extended to determine which type of graft resulted in greatest bone formation.

CONCLUSION

When comparing ridge preservation with NH, only 3 studies encountered a greater amount of newly formed bone in the ridge preservation group, whereas the rest did not find statistically significant differences or even observed a greater percentage of newly formed bone in the control group. Therefore, more studies are needed to determine whether the use of graft materials enhances new bone formation in contrast to NH alone and to determine the most effective bone grafting material.

Test in canine extraction site preservations by using mineralized collagen plug with or without membrane

The aim of this study was to discuss the feasibility of porous mineralized collagen plug and bilayer mineralized collagen-guided bone regeneration membrane in site preservation in extraction sockets. The third mandibular premolars on both sides were extracted from four dogs, thus there were 16 alveolar sockets in all dogs and were randomly assigned into three groups. Group A had six alveolar sockets, and groups B and C had five alveolar sockets, respectively. Each alveolar socket of group A was immediately implanted with a porous mineralized collagen plug and covered with a bilayer mineralized collagen-guided bone regeneration membrane after tooth extraction. Alveolar sockets of group B were implanted with porous mineralized collagen plug only, and group C was set as blank control without any implantation. The healing effects of the extraction sockets were evaluated by gross observation, morphological measurements, and X-ray micro-computed tomography after twelve weeks. Twelve weeks after operation, both groups A and B had more amount of new bone formation compared with group C; in terms of the degree of alveolar bone height, group A was lower than groups B and C with significant differences; the bone mineral density in the region of interest and bone remodeling degree in group A were higher than those of groups B and C. As a result, porous mineralized collagen plug could induce the regeneration of new bone in extraction socket, and combined use of porous mineralized collagen plug and bilayer mineralized collagen guided bone regeneration membrane could further reduce the absorption of alveolar ridge and preserve the socket site.

Evaluation of the zone of keratinized tissue using exposed acellular dermal matrix over tooth extraction sites: a randomized controlled clinical trial

BACKGROUND

The presence of an adequate zone of keratinized tissue has been associated with implant health. This study evaluated the zone of keratinized tissue using exposed acellular dermal matrix (ADM) over extraction sites.

MATERIAL AND METHODS

Fifteen sites received ADM, and fifteen control sites received no biomaterial. All sites were sutured with no attempt to achieve primary closure. Initial measurements of buccal and lingual keratinized tissue were taken from the mucogingival line (MGL) to the most coronal gingival margins. Final measurements were taken from the buccal MGL to the lingual MGL 90 days after surgery. Gingival biopsies were taken before implant placement.

RESULTS

Test and control groups exhibited a mean value of 4.40 ± 1.45 mm and 1.40 ± 1.40 mm, respectively. The newly formed tissue revealed similar histological aspect of normal keratinized tissue.

CONCLUSION

Exposed ADM used over tooth extraction sockets can predictably be used to increase the zone of keratinized tissue.

Alveolar ridge preservation of an extraction socket using autogenous tooth bone graft material for implant site development: prospective case series

This case series evaluated the clinical efficacy of autogenous tooth bone graft material (AutoBT) in alveolar ridge preservation of an extraction socket. Thirteen patients who received extraction socket graft using AutoBT followed by delayed implant placements from Nov. 2008 to Aug. 2010 were evaluated. A total of fifteen implants were placed. The primary and secondary stability of the placed implants were an average of 58 ISQ and 77.9 ISQ, respectively. The average amount of crestal bone loss around the implant was 0.05 mm during an average of 22.5 months (from 12 to 34 months) of functional loading. Newly formed tissues were evident from the 3-month specimen. Within the limitations of this case, autogenous tooth bone graft material can be a favorable bone substitute for extraction socket graft due to its good bone remodeling and osteoconductivity.

Comparison of ADM and Connective Tissue Graft as the Membrane in Class II Furcation Defect Regeneration: A Randomized Clinical Trial

Background and aims. Furcally-involved teeth present unique challenges to the success of periodontal therapy and influence treatment outcomes. This study aimed to assess to compare use of ADM and connective tissue membrane in class II furcation defect regeneration.

Materials and methods. 10 patient with 2 bilaterally class II furcation defects in first and/or second maxilla or man-dibular molar without interproximal furcation involvement, were selected. Four weeks after initial phase of treatment, before and thorough the surgery pocket depth (PD), clinical attachment level to stent (CAL-S), free gingival margin to stent(FGM-S) , crestal bone to stent (Crest-S), horizontal defect depth to stent (HDD-S) and vertical defect depth to stent (VDD-S) and crestal bone to defect depth measured from stent margin. Thereafter, one side randomly treated using connective tissue and DFDBA (study group) and opposite side received ADM and DFDBA (control group). After 6 months, soft and hard tissue parameters measured again in re-entry.

Results. Both groups presented improvements after therapies (P & 0.05). No inter-group differences were seen in PD re-duction (P = 0.275), CAL gain (P = 0.156), free gingival margin (P = 0.146), crest of the bone (P = 0.248), reduction in horizontal defects depth (P = 0.139) and reduction in vertical defects depth (P = 0.149).

Conclusion. Both treatments modalities have potential of regeneration without any adverse effect on healing process. Connective tissue grafts did not have significant higher bone fill compared to that of ADM.

Ridge preservation for implant therapy: a review of the literature

Healing of the extraction socket after tooth removal involves retention of the blood clot followed by a sequence of events that lead to changes in the alveolar process in a three dimensional fashion. This normal healing event results in a minimal loss of vertical height (around 1 mm), but a substantial loss of width in the buccal-lingual plane (4-6 mm). During the first three months following extraction that loss has been shown to be significant and may result in both a hard tissue and soft tissue deformity affecting the ability to restore the site with acceptable esthetics. Procedures that reduce the resorptive process have been shown to be predictable and potentially capable of eliminating secondary surgery for site preparation when implant therapy is planned. The key element is prior planning by the dental therapist to act at the time of extraction to prevent the collapse of the ridge due to the loss of the alveolus. Several techniques have been employed as ridge preservation procedures involving the use of bone grafts, barrier membranes and biologics to provide a better restorative outcome. This review will explore the evidence behind each technique and their efficacy in accomplishing site preparation. The literature does not identify a single technique as superior to others; however, all accepted therapeutic procedures for ridge preservation have been shown to be more effective than blood clot alone in randomized controlled studies.

Parathyroid hormone related to bone regeneration in grafted and nongrafted tooth extraction sockets in rats

OBJECTIVE

The quality and quantity of bone formed in tooth extraction sockets impact implant therapy. Therefore, the establishment of a new approach to enhance bone formation and to minimize bone resorption is important for the success of implant therapy. In this study, we investigated whether intermittent parathyroid hormone (PTH) therapy enhanced bone formation in grafted sockets.

METHODS

Tooth extractions of the maxillary first molars were performed in rats, and the sockets were grafted with xenograft. Intermittent PTH was administered either for 7 days before extractions, for 14 days after extractions, or both. The effect of PTH therapy on bone formation in the grafted sockets was assessed using microcomputed tomography at 14 days after extractions.

RESULTS

PTH therapy for 7 days before extractions was not effective to augment bone fill, whereas PTH therapy for 14 days after operation significantly augmented bone formation in the grafted sockets.

CONCLUSIONS

Intermittent PTH therapy starting right after tooth extractions significantly enhanced bone fill in the grafted sockets, suggesting that PTH therapy can be a strong asset for the success of the ridge preservation procedure.

Alveolar ridge preservation techniques: a systematic review and meta-analysis of histological and histomorphometrical data

AIM

The aim of this article was to systematically review histological and histomorphometrical data from literature that provide information regarding the effect of alveolar ridge preservation procedures on healing after tooth extraction in humans.

MATERIALS AND METHODS

The MEDLINE-PubMed and the Cochrane CENTRAL databases were searched up to September 2012; 38 papers were selected from 646 founded. A meta-analysis was performed regarding the variations in the mean percentage of Bone, Connective Tissue and Residual Graft Material between three different types of Procedures.

RESULTS

The highest value regarding bone percentages is produced at 3 months by Procedures with Allografts (54.4%), while the lowest is obtained, at 5 months, by those using Xenografts (23.6%). Referring to connective tissue, the highest and lowest values are shown at 7 months, with Allografts (67%) and Alloplasts (27.1%), respectively. Regarding residual graft material, the lowest rates are displayed by Procedures with Allografts (12.4-21.11%), while those using Xenografts and Alloplasts showed the best results at 7 months (37.14 and 37.23%). No statistical difference was found.

CONCLUSIONS

With the limitations due to the features of the selected papers, no major histological and histomorphometrical differences arose among different procedures or when compared to spontaneous healing. Thus, it might be argued that in preserved sites it is unnecessary to wait over 3 to 4 months prior to implant insertion.

Postextraction alveolar ridge preservation: biological basis and treatments

Following tooth extraction, the alveolar ridge undergoes an inevitable remodeling process that influences implant therapy of the edentulous area. Socket grafting is a commonly adopted therapy for the preservation of alveolar bone structures in combination or not with immediate implant placement although the biological bases lying behind this treatment modality are not fully understood and often misinterpreted. This review is intended to clarify the literature support to socket grafting in order to provide practitioners with valid tools to make a conscious decision of when and why to recommend this therapy.

Ridge preservation of the molar extraction socket using collagen sponge and xenogeneic bone grafts

OBJECTIVE

The purpose of this study was to evaluate the efficacy of the alveolar ridge preservation technique using collagen sponge and xenograft after extraction.

STUDY DESIGN

Twenty patients were divided into the control group and the experimental group, which contained about 10 patients each. The control group patients were planned 3-unit bridge without performing implant and without special treatments for the extraction socket, and prosthetic treatments were performed after 3 months. In the experimental group, using collagen sponge and xenogeneic bone graft, alveolar ridge preservation was performed simultaneously with tooth extraction; implants were placed after 3 months. Clinical and histological evaluations and statistical analysis were performed.

RESULTS

The resorption rate of the width of alveolar bone 3 mm below the alveolar ridge of the control group was shown to be 20.74% and of the experimental group was an average of 14.26%, approximately a difference of 6% was observed, and it was statistically significant. New bone formation in the vicinity of bone graft materials was achieved well, and inflammation findings were not observed.

CONCLUSION

The results indicated that in the ridge preservation using collagen sponge and xenograft, xenograft prevents the horizontal resorption of the alveolar ridge, and the upper collagen sponge blocks the infiltration of soft tissues to the lower area, and thus it has the advantage of the enhancement of bone fill.

Mucogingival surgery: where we stand today

Mucogingival problems are developmental and acquired aberrations in the morphology, position, and/or the amount of gingiva surrounding teeth. According to an academic report by American Academy of Periodontology, mucogingival therapy should be advocated for gingival augmentation and to create adequate vestibular depth in areas with insufficient attached gingiva. This paper provides an overview on mucogingival surgical procedures from its inception to the current time.

Healing of extraction sockets filled with BoneCeramic® prior to implant placement: preliminary histological findings

BACKGROUND

Various grafting materials have been designed to minimize edentulous ridge volume loss following tooth extraction by encouraging new bone formation in healing sockets. BoneCeramic® is a composite of hydroxyapatite and bèta-tricalcium phosphate with pores of 100-500 microns.

PURPOSES

The aim of this study was to evaluate bone regeneration in healing sockets substituted with BoneCeramic® prior to implant procedures.

MATERIALS AND METHODS

Fifteen extraction sockets were substituted with BoneCeramic® and 14 sockets were left to heal naturally in 10 patients (mean age 59.6 years). Biopsies were collected only from the implant recipient sites during surgery after healing periods ranging from 6-74 weeks (mean 22). In total, 24 biopsies were available; 10 from substituted and 14 from naturally healed sites. In one site, the implant was not placed intentionally and, in four substituted sites, implant placement had to be postponed due to inappropriate healing, hence from five sites biopsies were not available. Histological sections were examined by transmitted light microscope.

RESULTS

At the time of implant surgery, bone at substituted sites was softer than in controls, compromising initial implant stability. New bone formation at substituted sites was consistently poorer than in controls, presenting predominantly loose connective tissue and less woven bone.

CONCLUSION

The use of BoneCeramic® as a grafting material in fresh extraction sockets appears to interfere with normal healing processes of the alveolar bone. On the basis of the present preliminary findings, its indication as a material for bone augmentation, when implant placement is considered within 6-38 weeks after extraction, should be revised.

Ridge preservation with acellular dermal matrix and anorganic bone matrix cell-binding peptide P-15 after tooth extraction in humans

BACKGROUND

Preventing ridge collapse with the extraction of maxillary anterior teeth is vital to an esthetic restorative result. Several regenerative techniques are available and are used for socket preservation. The aim of this study is to analyze by clinical parameters the use of acellular dermal matrix (ADM) and anorganic bovine bone matrix (ABM) with synthetic cell-binding peptide P-15 to preserve alveolar bone after tooth extraction.

METHODS

Eighteen patients in need of extraction of maxillary anterior teeth were selected and randomly assigned to the test group (ADM plus ABM/P-15) or the control group (ADM only). Clinical measurements were recorded initially and at 6 months after ridge-preservation procedures.

RESULTS

In the clinical measurements (external vertical palatal measurement [EVPM], external vertical buccal measurement [EVBM], and alveolar horizontal measurement [AHM]) the statistical analysis showed no difference between test and control groups initially and at 6 months. The intragroup analysis, after 6 months, showed a statistically significant reduction in the measurements for both groups. In the comparison between the two groups, the differences in the test group were as follows: EVPM = 0.83 ± 1.53 mm; EVBM = 1.20 ± 2.02 mm; and AHM = 2.53 ± 1.81 mm. The differences in the control group were as follows: EVPM = 0.87 ± 1.13 mm; EVBM = 1.50 ± 1.15 mm; and AHM = 3.40 ± 1.39 mm. The differences in EVPM and EVBM were not statistically significant; however, in horizontal measurement (AHM), there was a statistically significant difference (P<0.05).

CONCLUSION

The results of this study show that ADM used as membrane associated with ABM/P-15 can be used to reduce buccal-palatal dimensions compared to ADM alone for preservation of the alveolar ridge after extraction of anterior maxillary teeth.

Comparison of dermal matrix and polytetrafluoroethylene membrane for socket bone augmentation: a clinical and histologic study

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Effect of absorbable membranes on sandwich bone augmentation

OBJECTIVES

This study was conducted to evaluate the effect of barrier membranes on sandwich bone augmentation (SBA) for the treatment of implant dehiscence defects.

MATERIAL AND METHODS

Twenty-six implant-associated buccal dehiscence defects in 22 patients were treated according to the SBA concept - mineralized human cancellous allograft (inner layer), mineralized human cortical allograft (outer layer) and coverage with barrier membrane. The defects were randomly assigned to the bovine collagen membrane (BME) group; acellular dermal matrix (ADM) group; and no membrane group. Measurements at baseline and 6 months re-entry included defect height (DH: from smooth-rough junction to the most apical part of the defect), defect width (DW: at the widest part of the defect), and horizontal defect depth (HDD: at three locations - smooth-rough junction, middle, and most apical portion of the defect). All measurements were taken from a reference stent. Statistical analyses were performed for comparison of intra- and inter-group comparisons.

RESULTS

All implants placed were successfully osseointegrated. DH at baseline for three groups were not significantly different (P=0.858). Mean % DH reductions for ADM, BME, and control groups at 6 months were 73.9+/-17.6%, 68.1+/-30.1%, and 63.6+/-23.9%, respectively, with no significant difference among the groups (P=0.686). Mean horizontal bone gain, however, was significantly greater for membrane groups (1.7 mm for ADM, 1.6 mm for BME) compared with control group (1 mm) (P=0.044). Implant exposure resulted in significant reduction in total height gain (79.1+/-14.3% vs. 57+/-23.5%, P=0.021).

CONCLUSIONS

Within the limit of this study, it is concluded that SBA technique achieved predictable clinical outcomes. The addition of absorbable membranes enhanced bone gain in thickness compared with membrane-treated sites.

The effect of simvastatin on remodelling of the alveolar bone following tooth extraction

Suppression of residual ridge resorption after tooth extraction is a hot spot in dental research. Recently, simvastatin was reported to influence bone turnover by stimulating bone formation. In this study, the effect of simvastatin application on residual ridge resorption following tooth extraction was investigated. Sixty male Wistar rats were randomly divided into experimental and control groups (n=30). Polylactic acid/polyglycolic acid copolymer carriers, with or without simvastatin, were implanted into extraction sockets of right mandibular incisors. The rats were killed at 1, 2, 4, 8 or 12 weeks after implantation. The relative height of the residual alveolar ridge was significantly greater in the experimental compared to the control group at 2, 4, 8 and 12 weeks. The bone mineral density in the experimental group was significantly higher than that in the control group at 4, 8 and 12 weeks. A larger newly formed bone island was observed in the experimental group at 4 weeks, and higher bone formation rate and quality were found than in the control group at different time points except 1 week. The findings indicate that local application of simvastatin would effectively preserve the residual alveolar bone by promoting bone formation in the extraction socket.

Ridge Expansion With Acellular Dermal Matrix and Deproteinized Bovine Bone: A Case Report

Reduction of the original height and width of the alveolar bone of an edentulous site precludes optimal positioning of implant fixtures and may esthetically compromise the prosthesis. Ridge expansion at the time of extraction can prevent the need for ridge reduction and reduces the number of surgical interventions.A patient with a narrow ridge with buccal deformity was treated for the staged placement of an implant. The tooth was extracted. The socket was expanded with an osteotome and an acellular dermal matrix graft was applied as a barrier membrane. The underlying bone showed good healing with maturity and the acellular dermal matrix had the potential to increase the keratinized tissue in the extraction area.

Acellular Dermal Matrix as a Membrane for Guided Tissue Regeneration in the Treatment of Class II Furcation Lesions: A Histometric and Clinical Study in Dogs

BACKGROUND

The purpose of this study was to evaluate acellular dermal matrix (ADM) as a membrane for guided tissue regeneration (GTR) in the treatment of mandibular Class II furcation lesions and to compare it to a bioabsorbable membrane.

METHODS

Class II furcation lesions were created surgically and chronified in six mongrel dogs on the buccal surfaces of mandibular third and fourth premolars, bilaterally. After 1 month, GTR was performed. Each side was assigned randomly to the control group (CGr: bioabsorbable membrane made of polyglycolic acid: trimethylene carbonate) or the test group (TGr: ADM as a membrane). Clinical measurements of the width and thickness of the keratinized tissue (WKT and TKT, respectively) were made before GTR. The dogs were sacrificed 12 weeks following GTR, and histomorphometric analysis was performed. Area measurements were taken of new tissue, epithelium, connective tissue, and new bone; bone height and new cementum were measured.

RESULTS

The formation of new bone, cementum, and periodontal ligament were similar in both groups. There were no statistically significant differences between the groups for any histomorphometric measurement. The TGr had a statistically significant increase in WKT and TKT after 3 months. The mean TKT gain was 1.03 mm for the TGr and 0.26 mm for the CGr (P <0.05).

CONCLUSION

The ADM demonstrated histomorphometric results similar to the bioabsorbable membrane and resulted in a greater increase in the thickness of the keratinized tissue.

Effect of In Vitro Gingival Fibroblast Seeding on the In Vivo Incorporation of Acellular Dermal Matrix Allografts in Dogs

BACKGROUND

Acellular dermal matrix allograft (ADMA) has been used in various periodontal procedures with successful results. Because ADMA has no blood vessels or cells, slower healing and incorporation are observed compared to a subepithelial connective tissue graft. Fibroblasts accelerate the healing process by regulation of matrix deposition and synthesis of a variety of growth factors. Thus, the objective of this study was to evaluate histologically if gingival fibroblasts affect healing and incorporation of ADMA in dogs when used as a subepithelial allograft.

METHODS

Gingival fibroblasts were established from explant culture from the connective tissue of keratinized gingiva collected from the maxilla of seven mongrel dogs. ADMA was seeded with gingival fibroblasts and transferred to dogs. Surgery was performed bilaterally, and the regions were divided into two groups: ADMA+F (ADMA containing fibroblasts) and ADMA (ADMA only). Biopsies were performed after 2, 4, and 8 weeks of healing.

RESULTS

The quantity of blood vessels was significantly higher in the ADMA+F group at 2 weeks of healing (Kruskal-Wallis; P <0.05). There was no statistical difference (P >0.05) in the number of cell layers, epithelial area, or inflammatory infiltrate between the two groups at any stage of healing.

CONCLUSION

The enhanced vascularization in vivo in early stages supports the important role of fibroblasts in improving graft performance and wound healing of cultured graft substitutes.