Influence of Implant transmucosal design on early peri-implant tissue responses in beagle dogs

Objectives: This study was undertaken to evaluate the influences of concave, machined and concave-roughened profiles of transmucosal implant designs on early peri-implant tissue responses. Materials and Methods: Implants were used and classified by transmucosal profile and surface type as straight-machined implants (SM), concave-machined implants (CM), or concave-roughened implants (CR). A total of 30 implants (10 per each type) with matching transmucosal profiles were placed directly on alveolar crests in randomized order in the edentulous mandibular ridges of three beagle dogs. Healing abutments were connected 4 weeks after implant placement, and prostheses were connected 8 weeks after implant placement and functionally loaded. All animals were sacrificed at 16 weeks. Peri-apical radiographs were obtained and measured to evaluate peri-implant marginal bone levels. Histological specimens were prepared to measure bone resorption, connective tissue contact, epithelial tissue height, biological width, and length of implant-abutment junction to the apical portion of junctional epithelium. Results: Radiographic and histometric analysis showed that least bone resorption occurred around CM implants and greatest bone resorption around SM implants (P < 0.05). Histometric analysis showed that highest connective tissue attachment and shortest biological width had formed around CM implants. Conclusion: Concave-machined profiled implants with a transmucosal design may induce less bone resorption and better connective tissue attachment around implants than the straight-machined profiled implants during the early healing phase.