Canine Study Finds Implant-Abutment Interface Configuration May Influence Crestal Bone Changes

Posted on October 28, 2014

This study was published in the September/October issue of The International Journal of Oral and Maxillofacial Implants (JOMI), the official journal of the Academy of Osseointegration (AO).

Background: Current implant protocols require not only osseointegration, but also high levels of soft tissue stability and esthetics. Crestal bone changes and their impact on soft tissue architecture are the most unpredictable and undesirable consequences of implant therapy, especially in the anterior maxilla. Hypotheses about the etiology of crestal bone remodeling around dental implants can be categorized into three main proposals: (1) mechanical factor that will disturb the surrounding tissues when occlusal forces are transmitted through the prosthetic component to the implant; (2) peri-implant inflammatory cell infiltrate caused by bacteria located at the implant/abutment microgap that will trigger crestal bone changes; (3) adaptive response of the biologic width to the local condition not related to stress factors or inflammatory factors.

Key Point: In this study, prototype test implants were fabricated to combine all current microgap and abutment profile variables. All implants integrated and there were no biologic or technical complications. The one-piece nonsubmerged implant design with a straight profile demonstrated the least crestal bone remodeling. Implant-abutment connections with a concave profile established crestal bone levels immediately apical to the concavity, regardless of the microgap variable.

Author: Dr. Santiago J. Caram, Department of Prosthodontics, Dental School, National University of Cuyo, Mendoza, Argentina, and Colleagues

Purpose: Scientists aimed to evaluate the peri-implant tissue response around different implant-abutment interface configurations when compared side-by-side. Two different soft tissue adaptation variables and three different microgap interface variables were analyzed.

Materials and Methods: Six different experimental implant abutment design groups – A to F – were evaluated in six mixed-breed dogs: (A) straight/matching; (B) straight/nonmatching; (C) straight/one-piece; (D) concave/matching; (E) concave/nonmatching; and (F) concave one-piece. At month 0, implant placement was performed and baseline standardized radiographs were taken. After three months of healing, standardized radiographs were taken and preformed titanium crowns were screw-retained to the top part of the abutments. Radiographs were taken every month for a period of six months. Dogs were fed a soft diet and implants were cleaned once each week with chemical and mechanical plaque control. 

Results: All implants (72) integrated successfully and remained stable during the entire study period. When comparing radiographs of groups with straight profiles, crestal bone remodeling in Group C (one-piece design), was significantly less than in Group A (matching diameters) and Group B (nonmatching diameter). Implant Group C (one-piece design) showed the least crestal bone remodeling of all groups. When comparing radiographs of groups with a concave profile but different microgap configurations, all three designs demonstrated bone loss with no significant differences among the three groups.  

For a complete copy of the study and the JOMI September/October “Table of Contents,” visit: http://www.osseo.org/NEWIJOMI.html. To join AO and begin receiving JOMI (bi-monthly) or obtain online access to JOMI, visit: http://www.osseo.org/NEWmembershipApply.html.

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