Thoma DS, et al. J Periodontal Implant Sci. 2017 Feb;47(1):2-12. https://doi.org/10.5051/jpis.2017.47.1.2

Aim: To assess the influence of the emergence angle on marginal bone loss (MBL) and supracrestal soft tissue around dental implants.Materials and Methods: In six mongrel dogs, the mandibular premolars and molars were extracted. After 3 months of healing, four dental implants were placed in each hemimandible. The implants were randomly allocated to receive one of four customized healing abutments, each with a different value of the restorative emergence angle: 20°, 40°, 60° or 80°. Intra‐oral radiographs were taken after placing the healing abutments and at 6, 9, 16 and 24 weeks of follow‐up. Then, micro‐CT and undecalcified histology and synchrotron were performed. MBL over time was analysed with generalized estimating equations (GEEs) and adjusted for baseline soft‐tissue thickness.Results: From implant placement to 24 weeks, GEE modelling showed that the MBL at mesial and distal sites consistently increased over time, indicating MBL in all groups (p < 0.001). The model indicated that MBL varied significantly across the different restorative angles (angle effect, p < 0.001), with 80° showing the greatest bone loss. Micro‐CT, histology and synchrotron confirmed the corresponding trends and showed that wide restorative angles (60° and 80°) impaired the integrity of the junctional epithelium of the supracrestal tissue.Conclusions: A wide restorative angle increases MBL and impairs the integrity of the junctional epithelium of the implant supracrestal complex.

Objectives: This study histologically analyzed biopsy samples obtained from sites of damaged extraction socket grafting using deproteinized bovine bone mineral (DBBM) or deproteinized porcine bone mineral (DPBM) with coverage by a collagen membrane.Material and methods: One hundred patients participated in this randomized controlled clinical trial of extraction socket grafts performed in cases of periodontally compromised teeth. All participants were blinded to their group allocations, and each material was grafted with coverage by collagen membranes after extraction of the tooth and removal of granulation tissue. At implant placement at 4 months, a biopsy was harvested at the implant site using a trephine was analyzed histologically.Results: Eighty‐five biopsy samples were acquired, of which 81 were finally included in the histologic analysis (42 in DBBM and 39 in DPBM group). Both DBBM and DPBM groups showed comparable proportions of residual biomaterial (12.37 ± 5.67% and 12.21 ± 5.75%, respectively), newly formed bone (15.07 ± 10.52% and 18.47 ± 11.47%, respectively), and nonmineralized tissue (72.56 ± 10.07% and 71.55 ± 15.47%, respectively). There were no significant differences in these histologic parameters between the two groups with different biomaterials.Conclusion: Comparable histologic bone formation was found in both socket grafted groups with DBBM or DPBM covered by collagen membranes in periodontally damaged extraction sockets. However, a wide variation in new bone formation was found after 4 months of postsurgical healing and a tendency of higher new bone formation was shown at damaged sockets that had an intact unilateral residual wall regardless of buccal or lingual side.

Aim: To assess the changes in peri‐implant soft tissue levels after the surgical treatment of peri‐implantitis.Methods: Randomized controlled trials, controlled clinical trials, cohort studies and case series, evaluating the changes in the position of the mucosal margin before and after surgical treatment of peri‐implantitis, were searched. Secondary outcomes were changes in keratinized mucosa (KM), radiographic bone levels, probing depths (PD), plaque indices, bleeding on probing and patient perception. Meta‐analyses were performed to determine weighted mean differences (WMD) or effects (WME).Results: Twenty‐six articles, reporting 20 investigations, were included. Reconstructive approaches yielded significantly less increase in mucosal recession, when compared to access flaps (n = 3, WMD = −1.35 mm, 95% confidence interval [CI] [−2.62; −0.07], p = .038). When comparing among reconstructive surgical interventions similar outcomes were observed irrespective of the use of a barrier membrane (n = 3, WMD = −0.01 mm, 95% CI [−0.15; 0.13], p = .917). When considering the effects over time, limited mucosal recession was observed after reconstructive procedures (n = 23, WME = 0.389 mm, 95% CI [0.204; 0.574]), p = .001), while increased recession was reported with either resective or access flap surgery (n = 6, WME = 1.21 mm, 95% CI [0.70; 1.72], p = <.001; and n = 3, WME = 0.95 mm, 95% CI [0.20; 2.10], p = .106; respectively). When resective and reconstructive approaches were combined the highest values on peri‐implant recession were reported (n = 2, WME = 1.97 mm, 95% CI [0.81; 3.14], p < .001). Reconstructive surgical interventions were associated with greater radiographic bone level gains, while similar values were reported for PD reduction when comparing reconstructive, access and resective procedures.Conclusions: Resective surgical procedures were associated with significant post‐surgical recession while minimal recession was observed in regenerative interventions.