Influence of Transmucosal Designs of Three One- Piece Implant Systems on Early Tissue Responses: A Histometric Study in Beagle Dogs

Purpose: The purpose of this study was to investigate the early tissue response around three one-piece implant systems with different transmucosal designs. Materials and Methods: Three one-piece dental implant systems with different profiles and surface roughnesses on the transmucosal portion were examined in the current study. The transmucosal portions were flared and machined (FM), concave and machined with microgrooves (CMG), or straight and anodic oxidized (SA). A total of 30 implants (10 of each type) were placed in computer-generated randomized order in the mandibular residual ridges of five beagle dogs. Six months later, all animals were sacrificed and histologic sections were prepared to measure epithelial tissue height, connective tissue contact, and the amount of bone resorption. One-way analysis of variance and the Bonferroni post hoc test were used for statistical evaluation (alpha = 95%). Results: After a 6-month nonfunctional loading period, all 30 implants were clinically immobile. Slight swelling and redness of the peri-implant soft tissue were noticed around most of the implant abutments. Histometric analysis showed that the FM implants had a longer epithelial tissue height than the CMG implants. The CMG implants showed the greatest amount of connective tissue attachment among the three groups and the least amount of marginal bone resorption. The CMG and SA implants showed bone growth above the initial reference point at 10 and 7 measurement sites, respectively, whereas no bone overgrowth was noted around the FM implants. Conclusion: Based on this study conducted in five beagle dogs, a concave transmucosal profile with a microgrooved surface was associated with longer connective tissue attachments and less bone resorption versus implants that were flared with a machined surface or straight with an anodic oxidized surface in the early healing phase. Keywords: connective tissue contact, dental implants, one-piece implant, transmucosal design