Effect of prosthetic emergence profile on labial transmucosal tissue in anterior implants: a retrospective cohort study.

Abstract

Purpose: There are no clear quantitative criteria for the prosthetic labial emergence profile in maxillary anterior implant treatment. We evaluated the impact of the prosthetic labial emergence profile on labial tissue alterations.

Materials and methods: We retrospectively analyzed 49 patients with 75 implants in the maxillary anterior region. Cone-beam computed tomography images were obtained at superstructure placement and 1 year later. Two parameters quantified the prosthetic labial emergence profile: (1) emergence angle (EA), defined as the angle between the tangent line from the implant-abutment junction to the superstructure and the implant axis; and (2) subgingival contour distance (SCD), the distance from the deepest concavity of the profile to the tangent line. Labial transmucosal tissue was evaluated by changes in gingival height (ΔGH) and bone height (BH) from the platform. Associations were analyzed using nonlinear least squares regression with robust estimators.

Results: A larger EA (≥ 30°) was associated with smaller ΔGH (overall Wald test p = .025). However, the pointwise 95% CI for the contrast between 21.2° and 30.95° included zero (- 0.57 to 0.08). A larger SCD (≥ 0.5 mm) was associated with significantly smaller ΔGH (p = .026; 95% CI, - 0.64 to - 0.10). Neither EA nor SCD showed significant associations with ΔBH.

Conclusions: EA ≥ 30° and SCD ≥ 0.5 mm may help suppress labial soft tissue recession within an esthetically acceptable range. These quantitative indicators provide guidance for prosthetic design in maxillary anterior implants and may contribute to improving esthetic outcomes.