Comparison of Two Different Abutment Designs on Marginal Bone Loss and Soft Tissue Development

Purpose: To assess the response of soft tissues around two different abutment designs in healed sites in the esthetic zone. Materials and Methods: Twenty-six subjects received two endosseous implants in healed, bilateral implant sites in the esthetic zone in the maxilla or the mandible. After 17 to 19 weeks and left/ right randomization, the implants were restored with either a conventional (control) or curved (experimental) titanium abutment and a provisional crown. Eight weeks after abutment placement, definitive crowns were cemented (T0). Soft tissue development was assessed based on peri-implant bone loss, Pink Esthetic Score (PES), and probing depths immediately after placement of the definitive crown and after 1 year (T12) and compared between sites. Possible confounding variables (abutment angle, plaque presence, gingival bleeding, width of attached mucosa) were also documented at T0 and T12. Results: The mean peri-implant marginal bone loss from T0 to T12 was 0.00 ± 0.37 mm in the experimental group and 0.12 ± 0.27 mm in the control group. Differences were not statistically significant (P = .25). At T12, the curved abutment scored a mean PES of 10 ± 2.3 and the straight abutment scored 9.7 ± 2.3. The difference was not significant (P = .46). Probing depths were also not significantly different between the two groups (P = .85). Correlation and regression analysis showed no hints of predictive behavior for the possible confounding variables. Conclusion: A titanium abutment with a circumferential curved design is of no additional benefit to soft tissue development and preservation of marginal bone compared to a conventional straight abutment design for the restoration of single-tooth implants in the esthetic zone. Keywords: abutment design, clinical study, esthetic zone, peri-implant bone loss, randomized clinical trial, soft tissue response