Influence of Interimplant Distance on Gingival Papilla Formation and Bone Resorption: Clinical-Radiographic Study in Dogs

Purpose: The purpose of this study was to evaluate in dogs the area between implants after prosthetic restoration within 5 mm distance between the contact point (CP) between crowns and the bone crest (BC). Materials and Methods: The mandibular premolars of 6 dogs were extracted bilaterally. After 12 weeks of healing, each dog received 8 implants. On each side, 2 implants were separated by 2 mm (group 1) and 2 by 3 mm (group 2). After a healing period (3 months), the implants were restored with temporary acrylic resin prostheses and after 4 more weeks, with definitive metallic prostheses. After 8 weeks, the distance between the CP and the papilla (P) was measured. The distance between a line extending from the CP and the gingival height at the distal extension of the prosthesis (DE) was also measured. Digital radiographic images were obtained for evaluation of the CP-BC and BC-P distances and the analysis of bone resorption adjacent to the implant surfaces. Results: The median CP-P distances were 1.75 mm and 1.98 mm for groups 1 and 2, respectively; the median CP-DE distances were 2.60 and 2.69, respectively. The mean CP-BC distances were 5.64 mm and 6.45 mm, for groups 1 and 2, respectively; mean BC-P distances were 3.07 mm and 3.55 mm, respectively. Discussion and Conclusions: The differences in distances of 2 and 3 mm between implants did not present significant differences in the formation of papillae or in crestal resorption. The CP-BC distances for prostheses should be different from those of natural teeth because in natural teeth, the biologic width is already present, and in the case of implant-supported prostheses, it will develop following second-stage surgery. Keywords: bone crest, bone resorption, contact point, gingival papilla, interimplant distance