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.

Background: The aim of this study was to characterize the efficacy of nano-hydroxyapatite-coated silk fibroin constructs as a scaffold for bone tissue engineering and to determine the osteogenic effect of human dental pulp and periodontal ligament derived cells at an early stage of healing in rabbits. 3D silk fibroin constructs were developed and coated using nano-hydroxyapatite crystals. Dental pulp and periodontal ligament cells from extracted human third molars were cultured and seeded onto the silk scaffolds prior to in vivo implantation into 8 male New Zealand White rabbits. Four circular windows 8 mm in diameter were created in the calvarium of each animal. The defects were randomly allocated to the groups; (1) silk scaffold with dental pulp cells (DPSS), (2) silk scaffold with PDL cells (PDLSS), (3) normal saline-soaked silk scaffold (SS), and (4) empty control. The animals were sacrificed 2 (n = 4) or 4 weeks (n = 4) postoperatively. The characteristics of the silk scaffolds before and after cell seeding were analyzed using SEM. Samples were collected for histologic and histomorphometic analysis. ANOVA was used for statistical analysis. Result: Histologic view of the experimental sites showed well-maintained structure of the silk scaffolds mostly unresorbed at 4 weeks. The SEM observations after cell-seeding revealed attachment of the cells onto silk fibroin with production of extracellular matrix. New bone formation was observed in the 4 week groups occurring from the periphery of the defects and the silk fibers were closely integrated with the new bone. There was no significant difference in the amount of bone formation between the SS group and the DPSS and PDLSS groups. Conclusion: Within the limitations of this study, silk scaffold is a biocompatible material with potential expediency as an osteoconductive scaffold in bone tissue engineering. However, there was no evidence to suggest that the addition of hDPCs and hPDLCs to the current rabbit calvarial defect model can produce an early effect in augmenting osteogenesis.

Background: In-vitro and animal studies using EDC cross-linked membranes have shown great resistance to enzymatic digestion as well as low cytotoxicity, and indicated its potential expediency as a barrier membrane for guided bone regeneration (GBR). The purpose of this study was to evaluate the efficacy, biocompatibility and degradation kinetics of a novel 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-cross-linked type I collagen membrane for regeneration of rabbit calvarial defects. EDC cross-linked type I collagen membrane and macroporous biphasic calcium phosphate (MBCP) consisting of 60 % hydroxyapatite and 40 % β-tricalcium phosphate were used in this study. Four circular defects (ø = 8 mm) were created in each calvarium of 12 male white rabbits. The experimental groups randomly allocated to the defects were as follows – (1) sham control, (2) EDC-cross-linked collagen membrane (EDC membrane), (3) bone graft (BG), and (4) bone graft with collagen membrane (B-EDC membrane). Specimens were harvested at 2 weeks ( n = 6) and 8 weeks ( n = 6) postoperatively for observational histology and histometrical analysis. Result: The histologic observation showed close adaptation of the EDC membrane to the defect perimeters along with vascularization of the membrane at 2 weeks. Direct apposition of new bone on to the collagen matrix could be observed displaying adequate tissue integration. Collapsing of the central portion of the membrane could be seen in the EDC membrane group, and both BG and B-EDC membrane groups showed greater total augmented area and new bone area than the EDC membrane group. The membrane was largely unresorbed at 2 weeks; and at 8 weeks the overall shape of the membrane was still maintained suggesting sustained barrier function at 8 weeks. Conclusion: Within the limits of this study, it may be concluded that EDC-cross-linked collagen membrane is a safe biomaterial with adequate tissue integration and resorption kinetics to support bone regeneration when used in conjunction with bone filler.