Alveolar crest contour changes after guided bone regeneration using different biomaterials: an experimental in vivo investigation.

OBJECTIVE: To evaluate the changes in alveolar contour after guided bone regeneration (GBR) with two different combinations of biomaterials in dehiscence defects around implants. MATERIAL AND METHODS: Chronic alveolar ridge defects were created bilaterally in the mandible of eight Beagle dogs. Once implants were placed, three treatment groups were randomly allocated to each peri-implant dehiscence defect: (i) test group received a bone substitute composed of hydroxyapatite (HA) and ß-tricalcium phosphate (ß-TCP) covered by a cross-linked collagen membrane, (ii) positive control group with placement of deproteinized bovine bone mineral (DBBM) plus a porcine natural collagen membrane, and (iii) a negative control with no treatment. Two healing periods (8 and 16 weeks) were evaluated. Dental casts were optically scanned, the obtained files were uploaded into an image analysis software and superimposed to evaluate the linear changes. RESULTS: In both healing periods, the gains in linear contours were higher in the test group and at the intermediate level (3 mm below the gingival margin). While at 8 weeks, no significant differences were found between the groups; at 16 weeks, the test and positive control groups demonstrated significant gains in contour compared with negative control. CONCLUSIONS: GBR using different biomaterials significantly increased the buccal contours of the alveolar crest when used at dehiscence defects around dental implants. CLINICAL RELEVANCE: Particulate highly porous synthetic bone substitute and a cross-linked collagen membrane demonstrated similar outcomes in terms of contour augmentation when compared to bovine xenograft (DBBM) and a collagen membrane.

Structural and histological differences between connective tissue grafts harvested from the lateral palatal mucosa or from the tuberosity area.

Tuberosity grafts had a greater percentage of lamina propria and lower percentage of submucosa when compared to lateral palate grafts. OBJECTIVE: The study aims to understand the differences in the structural composition of soft tissue autografts harvested from the lateral palate or the tuberosity. MATERIAL AND METHODS: Patients were randomly allocated to receive autografts harvested either from palatal or tuberosity sites to augment horizontal volume deficiencies around single-tooth implants. Tissue biopsies were analyzed for histological and histo-morphometric analysis. Picro-sirius red stain was used to evaluate collagen 1 and 3. Also, immuno-histochemical analysis was performed against MMP1, MMP2, cytokeratin-10, cytokeratin-13, and lysine hydroxylase-2. RESULTS: Twenty specimens were harvested from 9 subjects in the lateral palate group (PG) and 11 subjects in the tuberosity group (TG). The percentage of lamina propria represented 51.08% in the PG group and 72.79% in the TG group, while the area of submucosa was minimal in the TG group representing 4.89% of the total sample vs 25.75% in the PG. The total area of COL-1 and 3 in the TG was 1.19 ± 0.57 and 0.72 ± 0.44 mm2, respectively, while in the PG, the corresponding values were 1.4 ± 0.7 and 1.04 ± 0.5 mm2. The immuno-histochemical analysis generally showed a higher expression of LLH-2, MMP2, CYT-10, and CYT-13 in the TG when compared with the PG. CONCLUSION: Tuberosity grafts had a greater percentage of lamina propria and lower percentage of submucosa. The collagen content in the lamina propria was similar for both groups while the immuno-histochemical profile showed differences in the antibody expression of the epithelial cells. CLINICAL RELEVANCE: Tuberosity grafts had more lamina propria and less submocusa, which may be beneficial for volume augmentation.

Contour changes after guided bone regeneration of large non-contained mandibular buccal bone defects using deproteinized bovine bone mineral and a porcine-derived collagen membrane: an experimental in vivo investigation.

OBJECTIVE: The objective of this study was to evaluate soft tissue contour changes after three different regenerative therapies in chronic ridge defects. MATERIAL AND METHODS: Buccal bone defects were created in the mandible of nine beagle dogs. Augmentation procedures were performed 3 months later using a bone replacement graft (BRG), resorbable collagen membrane (MBG), or a combination of both procedures (CBG). Silicone impressions were taken before tooth extraction (T1), before the augmentation procedure (T2), and 3 months after the regenerative surgeries (T3). Casts were optically scanned and stereolithography files were superimposed to analyze the horizontal changes in ridge contours. RESULTS: After defect creation, most part of the horizontal changes occurred 4 and 6 mm below the gingival margin. In the mesial defect (D1) at T3, the mean horizontal gain in MBG amounted to 0.47 ± 0.34 mm, 0.79 ± 0.67 mm in the BRG, and 0.87 ± 0.69 mm for the CBG. In the middle defect (D2), the mean changes for the MBG were 0.11 ± 0.31, 1.01 ± 0.91 for the BRG, and 0.98 ± 0.49 for the CBG. The mean changes in the distal defect (D3) amounted to 0.24 ± 0.72 for the MBG, 1.04 ± 0.92 for the BRG, and 0.86 ± 0.56 for the CBG. The differences reached significance in all defects for the comparison MBG-BRG and MBG-CBG, while similar parameters were observed for the comparison BRG-CBG. CONCLUSION: BRG and CBG were equally effective and superior to MBG in increasing the horizontal tissue contours. The augmentation seldom reached the values before extraction. CLINICAL RELEVANCE: Scaffolding materials are needed for contour augmentation when using resorbable collagen membranes.

Effectiveness of Lateral Bone Augmentation on the Alveolar Crest Dimension: A Systematic Review and Meta-analysis.

Lateral ridge augmentation procedures are aimed to reconstruct deficient alveolar ridges or to build up peri-implant dehiscence and fenestrations. The objective of this systematic review was to assess the efficacy of these interventions by analyzing data from 40 clinical studies evaluating bone augmentation through either the staged or the simultaneous approach. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guideline for systematic reviews was used. The primary outcomes were the changes at reentry, in the ridge width, and in the vertical and horizontal dimensions of the peri-implant defect, measured in millimeters, in the staged and simultaneous approaches, respectively. The results of the meta-analysis showed, for the simultaneous approach, a statistically significant defect height reduction when all treatments were analyzed together (weighted mean difference [WMD] = -4.28 mm; 95% confidence interval: [CI] -4.88, -3.69; P < 0.01). The intervention combining bone replacement grafts with barrier membranes was associated with superior outcomes The most frequently used intervention was the combination of xenograft and bioabsorbable membrane. Similarly, for the staged approach, there was a statistically significant horizontal gain when all treatment groups were combined (WMD = 3.90 mm; 95% CI: 3.52, 4.28; P < 0.001). The most frequently used intervention was the use of autogenous bone blocks. Both treatment strategies led to high survival and success rates (>95%) for the implants placed on the regenerated sites. Nonexposed sites gained significantly more in the simultaneous and staged approaches (WMD = 1.1 and 3.1 mm).