Platelet-rich fibrin and bovine porous bone mineral vs. platelet-rich fibrin in the treatment of intrabony periodontal defects.

BACKGROUND AND OBJECTIVE: Bovine porous bone mineral (BPBM) is a xenograft that has been successfully utilized in periodontal regeneration. Platelet-rich fibrin (PRF) is a leukocyte and platelet preparation that concentrates various polypeptide growth factors and therefore has the potential to be used as regenerative treatment for periodontal defects. The purpose of this study was to examine the suitability of autologous PRF as regenerative treatment for periodontal intrabony defects in humans and to examine the ability of BPBM to augment the regenerative effects exerted by PRF. MATERIAL AND METHODS: Using a split-mouth design, 17 paired intrabony defects were randomly treated either with PRF or with PRF-BPBM combination. Re-entry surgeries were performed at 6 mo. Primary study outcomes were changes in pocket depth, attachment level and defect fill. RESULTS: Preoperative pocket depths, attachment levels and transoperative bone measurements were similar for the PRF and PRF-BPBM groups. Postsurgical measurements revealed a significantly greater reduction in pocket depth in the PRF-BPBM group (4.47±0.78 mm on buccal and 4.29±0.82 mm on lingual sites) when compared with the PRF group (3.35±0.68 mm on buccal and 3.24±0.73 mm on lingual sites). The PRF-BPBM group presented with significantly greater attachment gain (3.82±0.78 mm on buccal and 3.71±0.75 mm on lingual sites) than the PRF group (2.24±0.73 mm on buccal and 2.12±0.68 mm on lingual sites). Defect fill was also greater in the PRF-BPBM group (4.06±0.87 mm on buccal and 3.94±0.73 mm on lingual sites) than in the PRF group (2.21±0.68 mm on buccal and 2.06±0.64 mm on lingual sites). CONCLUSION: The results of this study indicate that PRF can improve clinical parameters associated with human intrabony periodontal defects, and BPBM has the ability to augment the effects of PRF in reducing pocket depth, improving clinical attachment levels and promoting defect fill.

The effectiveness of enamel matrix proteins used in combination with bovine porous bone mineral in the treatment of intrabony defects in humans.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of enamel matrix proteins (EMPs) used in combination with bovine porous bone mineral (BPBM), compared to open flap debridement (OFD) in the treatment of intrabony defects in humans. MATERIAL AND METHODS: Using a split-mouth design, 24 paired intrabony defects were surgically treated and re-entered 6 months later. Experimental sites were treated with EMPs and grafted with BPBM. Control sites were treated with an OFD. The primary outcomes evaluated in the study were changes in pocket depth, clinical attachment level and defect bone fill. RESULTS: Preoperative pocket depths, attachment levels and intra-operative bone measurements were similar for control and experimental sites. 6-month post surgical measurements revealed a significantly greater reduction in pocket depth (differences of 2.35+/-0.86 mm on buccal and 2.28+/-0.90 mm on lingual measurements) and more gain in clinical attachment (differences of 2.04+/-0.28 mm on buccal and 1.99+/-0.26 mm on lingual measurements) in the experimental sites. Surgical reentry of the defects revealed a significantly greater amount of defect fill in favor of the experimental sites (differences of 2.85+/-0.28 mm on buccal and 2.67+/-0.33 mm on lingual measurements). CONCLUSIONS: The results of this study suggest that combining EMPs and BPBM as a regenerative technique for intraosseous defects results in statistically and clinically significant more favorable results than OFD. The nature of the attachment between the newly regenerated tissue and the root surfaces needs to be evaluated histologically to confirm the presence of new attachment.

The use of bovine porous bone mineral in combination with enamel matrix proteins or with an autologous fibrinogen/fibronectin system in the treatment of intrabony periodontal defects in humans.

BACKGROUND: Enamel matrix derivative (EMD) and autologous fibrinogen/fibronectin system (AFFS) are agents that have been shown to be effective in periodontal regeneration. Their use in combination with graft materials, however, has not been extensively examined. The purpose of this study was to compare the clinical effectiveness of bovine porous bone mineral (BPBM) used in combination with an EMD or in combination with AFFS as regenerative treatments for periodontal intrabony defects in humans. METHODS: Twenty-three paired intrabony defects were surgically treated using a split mouth design. Defects were treated with BPBM either combined with EMD (BPBM/EMD) or with AFFS (BPBM/AFFS). The clinical parameters evaluated included changes in attachment level, probing depth, and defect fill as revealed by re-entry surgeries at 6 months. RESULTS: Preoperative probing depths, attachment levels, and transoperative bone measurements were similar for the 2 treatment groups. Postsurgical measurements taken at 6 months revealed that both treatment modalities resulted in clinically and statistically significant improvements in probing depth resolution, clinical attachment gain, and defect fill as compared to baseline. Both therapy modalities improved clinical parameters as compared to baseline, but the differences found between the groups were not statistically significant. CONCLUSIONS: The results of this study indicate that EMD and AFFS used in combination with BPBM have similar effects in promoting probing depth reduction, clinical attachment gain, and defect fill when employed as regenerative therapy for intraosseous lesions in humans. A study involving a larger sample size is necessary to statistically confirm the equivalence between the 2 treatment modalities.

Combination use of bovine porous bone mineral, enamel matrix proteins, and a bioabsorbable membrane in intrabony periodontal defects in humans.

BACKGROUND: The purpose of this study was to evaluate the effectiveness of a combination of enamel matrix proteins (EMP), bovine porous bone mineral (BPBM), and a bioabsorbable membrane for guided tissue regeneration (GTR) as regenerative therapy for intrabony defects in humans and compare it to an open flap debridement (OFD) technique. METHODS: Using a split-mouth design, 18 pairs of intrabony defects were treated and surgically reentered 6 months after the initial surgery. Experimental sites were treated with EMP, grafted with BPBM, and received a collagen/polylactic acid membrane for GTR. Control sites were treated with OFD. The primary outcomes evaluated in the study included probing depth resolution, clinical attachment gain, and bony defect fill. RESULTS: Preoperative probing depths, attachment levels, and intraoperative bone measurements were similar for the experimental and control groups. Postsurgical measurements taken at 6 months revealed a significantly greater reduction in probing depth in the experimental group (4.95+/-1.52 mm on buccal sites and 4.74+/-1.47 mm on lingual sites) when compared to the control group (2.83+/-0.83 mm on buccal sites and 2.90+/-0.91 mm on lingual sites). The experimental sites also presented with significantly more attachment gain (3.89+/-1.16 mm on buccal sites and 3.78+/-1.14 mm on lingual sites) than the control sites (1.52+/-0.83 mm on buccal sites and 1.48+/-0.78 mm on lingual sites). Surgical reentry of the treated defects revealed a significantly greater amount of defect fill in favor of the experimental group (4.76+/-1.36 mm on buccal sites and 4.81+/-1.37 mm on lingual sites) as compared to the control group (1.78+/-0.92 mm on buccal sites and 1.67+/-0.90 mm on lingual sites). CONCLUSIONS: The results of this study indicate that a combination technique including BPBM, EMP, and GTR results in better clinical resolution of intrabony defects than treatment with OFD. Differences observed were both statistically and clinically significant. The exact role of each of the 3 technique components in achieving the clinical improvement observed in this study remains to be determined.

Influence of bioactive glass on changes in alveolar process dimensions after exodontia.

BACKGROUND: Preservation of the alveolar process after tooth extraction is desirable because it facilitates placement of endosseous implants and minimizes adverse esthetic results associated with fixed partial dentures. The purpose of this study was to evaluate the clinical effectiveness of bioactive glass used as a graft material combined with calcium sulfate used in the form of a mechanical barrier in preserving alveolar ridges after tooth extraction. METHODS: Sixteen patients who required extraction of 2 anterior teeth or bicuspids participated in the study (split mouth design). After tooth extraction and elevation of a buccal full-thickness flap, experimental sockets were filled with bioactive glass, which in turn was covered with a layer of calcium sulfate. Control sites did not receive any graft or calcium sulfate. Titanium pins served as fixed reference points for measurements. No attempt was made to advance the flap to cover the socket areas on control or experimental sites (open socket approach). Reentry surgeries were performed at 6 months. RESULTS: Reentry surgeries showed that experimental sites presented with (1) significantly more internal socket bone fill (6.43 +/- 2.78 mm vs 4.00 +/- 2.33 mm on control sites), (2) less (although not statistically significantly less) resorption of alveolar bone height (0.38 +/- 3.18 mm vs 1.00 +/- 2. 25 mm on control sites), and (3) similar degree of horizontal resorption of the alveolar bony ridge as compared with controls (3. 48 +/- 2.68 mm vs 3.06 +/- 2.41 mm on control sites). CONCLUSIONS: This study suggests that treatment of extraction sockets with a combination of bioactive glass and calcium sulfate is of some benefit in preserving alveolar ridge dimensions after tooth extraction.

A comparison between enamel matrix proteins used alone or in combination with bovine porous bone mineral in the treatment of intrabony periodontal defects in humans.

BACKGROUND: It has been shown that clinical improvement of intrabony periodontal defects can be achieved with the use of enamel matrix proteins (EMPs) or by grafting with bovine porous bone mineral (BPBM). There is no report on the potential synergistic effect of EMPs and BPBM in periodontal regenerative therapy. The purpose of this study was to compare the clinical effectiveness of EMPs used alone or in combination with BPBM in the treatment of periodontal intrabony defects in humans. METHODS: Twenty-one paired intrabony defects were surgically treated using a split-mouth design. Intrabony defects were treated either with enamel matrix proteins (EMP group) or with enamel matrix proteins combined with bovine porous bone mineral (EMP/BPBM group). Re-entry surgeries were performed at 6 months. RESULTS: Preoperative probing depths, attachment levels, and transoperative bone measurements were similar for the EMP and EMP/BPBM groups. Postsurgical measurements taken at 6 months revealed a significantly greater reduction in probing depth in the EMP/BPBM group (3.43 +/- 1.32 mm on buccal sites and 3.36 +/- 1.35 mm on lingual sites) when compared to the EMP group (1.91 +/- 1.42 mm on buccal sites and 1.85 +/- 1.38 mm on lingual sites). The EMP/BPBM group also presented with significantly more attachment gain (3.13 +/- 1.41 mm on buccal sites and 3.11 +/- 1.39 mm on lingual sites) than the EMP group (1.72 +/- 1.33 mm on buccal sites and 1.75 +/- 1.37 mm on lingual sites). Surgical re-entry of the treated defects revealed a significantly greater amount of defect fill in favor of the EMP/BPBM group (3.82 +/- 1.43 mm on buccal sites and 3.74 +/- 1.38 mm on lingual sites) as compared to the EMP group (1.33 +/1.17 mm on buccal sites and 1.41 +/- 1.19 mm on lingual sites). CONCLUSIONS: The results of this study indicate that BPBM has the ability to augment the effects of EMPs in reducing probing depth, improving clinical attachment levels, and promoting defect fill when compared to presurgical levels.

A controlled re-entry study on the effectiveness of bovine porous bone mineral used in combination with a collagen membrane of porcine origin in the treatment of intrabony defects in humans.

AIM: The purpose of this study was to evaluate the clinical effectiveness of a bovine porous bone mineral used in combination with a porcine derived collagen membrane as a barrier in promoting periodontal regeneration in intrabony defects in humans. MATERIAL AND METHODS: The study employed a split-mouth design. 22 paired intrabony defects were treated and surgically re-entered 6 months after treatment. Experimental sites were grafted with bovine porous bone mineral and received a collagen membrane for guided tissue regeneration. Control sites were treated with an open flap debridement. RESULTS: Preoperative pocket depths, attachment levels and trans-operative bone measurements were similar for control and experimental sites. Post surgical measurements revealed a significantly greater reduction in pocket depth (differences of 1.89 +/- 0.31 mm on buccal 0.88 +/- 0.27 mm on lingual measurements) and more gain in clinical attachment (differences of 1.51 +/- 0.33 mm on buccal and 1.50 +/- 0.35 mm on lingual measurements) in experimental sites. Surgical reentry of the treated defects revealed a significantly greater amount of defect fill in favor of experimental sites (differences of 2.67 +/- 0.91 mm on buccal and 2.54 +/- 0.87 mm on lingual measurements). CONCLUSIONS: The results of this study indicate that clinical resolution of intrabony defects can be achieved using a combination of bovine porous bone mineral and an absorbable, porcine derived collagen membrane when employing a technique based on the principles of guided tissue regeneration. The nature of the attachment between the newly regenerated tissue and the root surfaces needs to be evaluated histologically to confirm the presence of new attachment.

The use of autogenous periosteal grafts as barriers for the treatment of intrabony defects in humans.

The purpose of this study was to evaluate the clinical effectiveness of a connective tissue graft including periosteum used as a barrier for guided periodontal tissue regeneration in interproximal bony defects. An open flap debridement of a comparable interproximal bony defect in the same patient was used as a control. This study was performed at 2 different clinical centers. Six paired defects were treated at one center, and 16 paired defects at the other. Reentry surgeries were performed at 6 months. Preoperative comparisons of control and experimental sites with respect to clinical parameters and osseous measurements were similar. Post-surgical experimental sites produced more gain in clinical attachment (1.25 mm on buccal and 1.25 mm on lingual sites at center A and 1.26 mm on buccal and 1.18 mm on lingual sites at center B) and osseous defect fill (1.84 mm on buccal and 2.00 mm on lingual sites at center A and 1.66 mm on buccal and 2.04 mm on lingual sites at center B) when compared to control sites. The results of this trial indicate that clinical resolution of interproximal periodontal defects can be obtained with periosteal grafts used as barriers.

Guided tissue regeneration in Class II furcation involved maxillary molars: a controlled study of 8 split-mouth cases.

The purpose of this study was to clinically evaluate the effectiveness of polytetrafluoroethylene membranes in the healing of interproximal Class II furcation defects in maxillary molars using a surgical treatment technique based on the principles of guided tissue regeneration. Eight subjects with similar bilateral Class II furcation lesions on the mesial aspect of maxillary first molars participated in this study. Patients received initial therapy consisting of oral hygiene instructions, scaling and root planing, and occlusal adjustment if necessary. Clinical parameters evaluated included plaque index, sulcular bleeding index, probing depth, attachment level, gingival recession, and open horizontal and vertical furcation fill. An acrylic occlusal stent was used to assure reproducibility of measurements. Experimental sites received a polytetrafluoroethylene membrane following surgical exposure of the furcation. Control sites were treated in the exact same manner but without a membrane. Membranes were removed at 6 weeks after the first surgery. Reentry surgeries were performed at 9 months. Postsurgical results showed a significant improvement in probing depth, attachment level, and open horizontal furcation fill for both groups when compared to baseline values, with experimental sites performing significantly better than controls. Control sites showed a slight loss in open vertical furcation fill while experimental sites remained unchanged. This study suggests that guided tissue regeneration using polytetrafluoroethylene membranes is of some but limited value in the treatment of maxillary molar interpoximal Class II furcation lesions.

Preservation of alveolar bone in extraction sockets using bioabsorbable membranes.

The purpose of this study was to evaluate the clinical effectiveness of a bioabsorbable membrane made of glycolide and lactide polymers in preserving alveolar ridges following tooth extraction using a surgical technique based on the principles of guided bone regeneration. Sixteen patients requiring extractions of 2 anterior teeth or bicuspids participated in the study (split-mouth design). Following elevation of buccal and lingual full-thickness flaps and extraction of teeth, experimental sites were covered with bioabsorbable membranes; control sites did not receive any membrane. Titanium pins served as fixed reference points for measurements. Flaps were advanced in order to achieve primary closure of the surgical wound. No membrane became exposed in the course of healing. Reentry surgeries were performed at 6 months. Results showed that experimental sites presented with significantly less loss of alveolar bone height, more internal socket bone fill, and less horizontal resorption of the alveolar bone ridge. This study suggests that treatment of extraction sockets with membranes made of glycolide and lactide polymers is valuable in preserving alveolar bone in extraction sockets and preventing alveolar ridge defects.

Evaluation of periosteal membranes and coronally positioned flaps in the treatment of Class II furcation defects: a comparative clinical study in humans.

The purpose of this study was to compare the clinical effectiveness of connective tissue grafts including periosteum used as a mechanical barrier for guided periodontal tissue regeneration and coronally positioned flaps in the treatment of Class II furcation defects. A total of 28 furcation defects were treated; 14 received a periosteal barrier and 14 received a coronally positioned flap. Reentry surgeries were performed at 6 months. No statistically significant differences were found preoperatively between the two treatment groups with respect to clinical parameters and osseous measurements. Postsurgically, both treatment modalities resulted in a significant decrease in probing depth and a significant gain in clinical attachment, but the differences observed were not statistically significant. The periosteal barrier group presented with a significantly better gain in vertical components of the alveolar bone (1.93 +/- 0.15 mm and 0.20 +/- 0.26 mm for periosteal barrier and coronally positioned flap groups, respectively; P < or = 0.001) and horizontal components of the alveolar bone (1.60 +/- 0.21 mm and 0.13 +/- 0.90 mm for periosteal barrier and coronally positioned flap groups, respectively; P < or = 0.001). The results of this trial indicate that similar clinical resolution of Class II furcation defects can be obtained with periosteal barriers and coronally positioned flaps. Periosteal barriers, however, are a better treatment alternative in achieving bone fill of the furcation area.

Histologic evaluation of guided tissue regeneration using 4 barrier membranes: a comparative furcation study in dogs.

This study evaluated and compared four different barrier membrane materials used to treat class II mandibular premolar and molar furcations in seven dogs with naturally occurring periodontitis. Five class II furcation defects in each animal were randomly assigned to one of four experimental groups or to a control group. Each defect was treated by surgical debridement, root planing, and barrier membrane coverage with one of the four test materials or no barrier membrane (control). Thus, each animal served as its own control. Following 6 months of healing, block sections were used to histologically measure the amount of regenerated tissue and stereometrically enumerate the inflammatory cell infiltration observed with each of the treatment modalities. The four barrier membrane materials (polycarbonate filter, silicone rubber, expanded polytetrafluoroethylene, and polycaprolactone) all provided a wound healing environment that promoted new cementum formation, with mean values ranging from 1.96 +/- 0.031 mm to 2.18 +/- 0.015 mm, and facilitated alveolar bone regeneration, with mean values ranging from 1.18 +/- 0.019 mm to 1.44 +/- 0.014 mm. Control-treated sites showed mean values of only 0.24 +/- 0.007 mm new cementum formation and 0.32 +/- 0.017 mm bone fill. Polycarbonate filter and polycaprolactone membrane barriers elicited a significantly greater chronic inflammatory cell response of lymphocyte and plasma cell infiltrates as compared to expanded polytetrafluoroethylene and silicone rubber, which were comparable to control-treated sites.

A bone regenerative approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases.

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.

Osteogenesis enhanced by chitosan (poly-N-acetyl glucosaminoglycan) in vitro.

Chitosan, with a chemical structure similar to hyaluronic acid, has been implicated as a wound healing agent. The purpose of this research was to evaluate the effect of chitosan on osteoblast differentiation and bone formation in vitro. Mesenchymal stem cells were harvested from fetal Swiss Webster mice calvariae prior to osteoblast differentiation and calcification (12 to 13 days in utero). Stem cells were seeded into 6-well culture plates at a density of 350,000 cells per well. Using this model, it was possible to quantify the influence of chitosan on osteoprogenitor differentiation and osteogenesis. Experimental wells were pretreated with 200 microliters chitosan (2 mg/ml in 0.2% acetic acid vehicle). Control wells were pretreated with 200 microliters vehicle (0.2% acetic acid) or remained untreated. Cells were allowed to grow under optimal conditions for 14 days. Cell cultures were fixed with glutaraldehyde and stained with Von Kossa stain to identify bone forming colonies. Positive staining colonies were identified and counted under light microscopy. Histologic cross-sections of representative positively stained colonies identified osteoblasts and confirmed bone formation. Examination of control wells revealed 3.6 +/- 0.6 colonies per well while experimental wells revealed a significantly greater average of 6.2 +/- 1.2 colonies per well (P < or = 0.01). Computer-assisted image analysis of the average area of bone formed by control colonies was 0.34 +/- 0.09 (relative units) while that of experimental colonies was 0.39 +/- 0.06 (relative units) per average bone forming colony. The difference in mean size (control versus chitosan bone forming colony) was not statistically significant (P = 0.4691). The results of this in vitro experiment suggest that chitosan potentiates the differentiation of osteoprogenitor cells and may facilitate the formation of bone.

In vitro comparison of aged and young osteogenic and hemopoietic bone marrow stem cells and their derivative colonies.

The purpose of this in vitro study was to determine whether there were differences in the number and size of osteogenic and hemopoietic colonies derived from bone marrow stem cells of aged and young adult male Sprague-Dawley rats. Using a Ficoll-Paque gradient, stem cells were harvested from aged male rats 18 to 22 months old and young adult males 55 days of age. Single cell suspensions from the red marrow of the long bones were cultured 14 days in vitro and subsequent colonies were assessed by light microscopy for number and size. A computerized histomorphometric linear measuring system was utilized to assess colony area in square millimeters. The results clearly show that young animals have a statistically significant increased cellular potential for osteogenic and hemopoietic colony formation. Cultures from aged animals showed an average formation of 0.45 +/- 0.6863 osteogenic colonies while those from younger animals had an average of 3.6 +/- 2.3523 osteogenic colonies per 3 million cells plated. Hemopoietic colonies from aged animal cell cultures numbered 5.25 +/- 2.2449 while those from the young animals averaged 8.23 +/- 3.3601 per 3 million cells plated. The difference in size of the osteogenic and hemopoietic colonies between age groups was not statistically significant. The area of osteogenic colonies derived from aged animals measured 0.1244 +/- 0.0891 mm2, while those derived from the young animals averaged 0.1276 +/- 0.0518 mm2. Hemopoietic colonies from the aged cells measured 0.0759 +/- 0.0514 mm2, while hemopoietic colonies from the young animal cells measured 0.06010 +/- 0.0180 mm2. The results of this study may have implications for consideration in the cellular healing aspects of aged versus young individuals.

Supracrestal bone formation around dental implants: an experimental dog study.

To test the osteopromotive activity in large non-spacemaking alveolar bone sites, a total of 20 titanium dental implants were placed superior to a previously modified mandibular alveolar process in five adult beagle dogs. The supracrestal implant position resulted in a mean buccal dehiscence of 5.1 +/- 1.03 mm and a mean supracrestal bone deficit of 2.69 +/- 0.45 mm. Three treatment groups were randomly assigned: group I, ten implants treated with a titanium-reinforced expanded polytetrafluoroethylene (ePTFE) membrane (TR); group II, six implants treated with a standard ePTFE membrane (ST); and group III, four implants that received no membrane (control). Before mucoperiosteal flap closure, the bone surface was perforated and peripheral blood was injected around the implants and underneath the membranes. Clinical evaluation of submerged implant sites showed evidence of complete regeneration of the peri-implant bone defects in groups I and II, minimal bone formation in control group III, and a widening of the ridge in group I. Corresponding histologic examination of undecalcified sections demonstrated large amounts of newly formed bone beneath both types of membranes with a superficial layer of loose connective tissue. Mean gain of supracrestal regenerated bone amounted to 1.82 +/- 1.04 mm (TR group), 1.90 +/- 0.30 mm (ST group), and 0.53 +/- 1.34 mm (control group). Mean bone regeneration at the buccal dehiscences was 3.33 +/- 1.44 mm (TR group), 2.46 +/- 0.51 mm (ST group), and 2.76 +/- 0.84 mm (control group). The TR membranes showed evidence of increased alveolar bone width compared to ST membranes and control sites. These results suggest that supracrestal bone regeneration can successfully be enhanced by a submerged membrane technique in the dog model and that the titanium-reinforced membranes were able to maintain a large, protected space for blood clot stabilization without the addition of bone grafts and produced a larger bone quantity when compared to standard membranes.

Guided tissue regeneration using calcium phosphate implants together with 4 different membranes. A study on furcations in dogs.

Four different membranes were used in conjunction with porous calcium phosphate granules to treat grade II furcations in lower molars of 6 dogs. Six months later block sections were used to measure the amount of regeneration and inflammation. The 4 membranes (polycarbonate, silicone rubber, polytetrafluoroethylene, and polycaprolactone) all gave similar improvements in bone fill ranging from 1.74 +/- 0.44 mm to 2.02 +/- 0.38 mm while control areas had only 0.34 +/- 0.12 mm. The amount of new attachment ranged from 2.32 +/- 0.62 mm to 2.58 +/- 0.62 mm for the membranes and was 0.26 +/- 0.11 mm for controls. There were increased numbers of chronic inflammatory cells seen with the polycarbonate and polycaprolactone group compared to controls and the other 2 membranes.

Osteopromotion as an adjunct to osseointegration.

Osteopromotion to enhance the formation of bone approximating implant surfaces can be obtained using bone regeneration techniques with polytetrafluoroethylene membranes. Treatment of dehiscences and other deficiencies of bone volume allows implants to be successfully placed in regions previously thought to be unsuitable. Bone regeneration is possible in peri-implant osteitis defects if appropriate surgical techniques are used.

The regenerative potential of plaque-induced peri-implant bone defects treated by a submerged membrane technique: an experimental study.

The aim of the present study was to experimentally induce peri-implant bone defects around three different types of implants by plaque accumulation and to determine whether new bone formation can occur on previously contaminated dental implants. Dental implants were placed into the mandibles of beagle dogs. Gross plaque accumulation around the implants was undisturbed for 3 months, which resulted in circumferential peri-implant bone defects. Bony defects surrounding the hydroxyapatite implants were significantly greater than those around the titanium implants. Surgical treatment consisted of granulation tissue removal, preparation of the implant surface, and the placement of an e-PTFE membrane over each test implant. Before the flap was closed to cover the implants, perforations were made into the cancellous bone. Each control implant received identical treatment, but without placement of a membrane. Surgical exposure after an uneventful submerged healing period showed evidence of closure of the peri-implant bone defects. Corresponding histologic examination of 2-month sections demonstrated large amounts of rapidly formed lamellar bone beneath the membrane. Some areas of the previously contaminated implant surface showed evidence of "re-osseointegration." These preliminary results support the hypothesis that plaque-induced peri-implant bone defects can be successfully treated by a submerged membrane technique in the dog model.