Anterior implant restorations with a convex emergence profile increase the frequency of recession: 12‐month results of a randomized controlled clinical trial

Abstract

Aim: To test whether the emergence profile (CONVEX or CONCAVE) of implantsupported crowns influences the mucosal margin stability up to 12 months after insertion of the final restoration.Materials and Methods: Forty-seven patients with a single implant in the anterior region were randomly allocated to one of three groups: (1) CONVEX (n = 15), implant provisional and an implant-supported crown both with a convex profile;(2) CONCAVE (n = 16), implant provisional and an implant-supported crown both with a concave profile; (3) CONTROL (n = 16), no provisional (healing abutment only) and an implant-supported crown. All patients were recalled at baseline, 6, and 12 months. The stability of mucosal margin along with clinical, aesthetic, and profilometric outcomes as well as time and costs were evaluated. To predict the presence of recession, multivariable logistic regressions were performed and linear models using generalized estimation equations were conducted for the different outcomes.Results: Forty-four patients were available at 12 months post-loading. The frequency of mucosal recession amounted to 64.3% in group CONVEX, 14.3% in group CONCAVE, and 31.4% in group CONTROL. Regression models revealed that a CONVEX profile was significantly associated with the presence of recessions (odds ratio: 12.6, 95% confidence interval: 1.82-88.48, p = .01) compared with the CONCAVE profile. Pink aesthetic scores amounted to 5.9 in group CONVEX, 6.2 in group CONCAVE, and 5.4 in group CONTROL, with no significant differences between the groups (p = .735). Groups CONVEX and CONCAVE increased the appointments and costs compared with the CONTROL group.Conclusions: The use of implant-supported provisionals with a CONCAVE emergence profile results in a greater stability of the mucosal margin compared with a CONVEX profile up to 12 months of loading. This is accompanied, however, by increased time and costs compared with the absence of a provisional and may not Marina Siegenthaler and Franz J. Strauss contributed equally to the manuscript and should be considered as joint first authors.

Clinical and radiographic peri‐implant tissue changes for implants restored with convex or concave abutment shapes: A 3‐year randomized controlled trial

“…In the present study, only maxillary premolars were included, and mucosa measurements were initiated at different time points (implant placement vs. crown placement). Thus, differences in the inclusion criteria and evaluation time points may in part explain differences in the observed outcomes with the previously mentioned study (Siegenthaler et al, 2022).…”

“…placement). Thus, differences in the inclusion criteria and evaluation time points may in part explain differences in the observed outcomes with the previously mentioned study (Siegenthaler et al, 2022).…”

“…In the present study, no significant differences in the facial peri‐implant mucosa position change over time were observed between the two groups. Recently, few clinical studies evaluated the influence of abutment emergence shape on peri‐implant mucosa changes for immediate implants (Seyssens et al, 2020) and implants placed with a delayed protocol (Siegenthaler et al, 2022). Seyseens et al identified a convex emergence profile as a putative risk factor for a facial mucosal recession for immediate implants over a period of 10 years.…”

“…Seyseens et al identified a convex emergence profile as a putative risk factor for a facial mucosal recession for immediate implants over a period of 10 years. Similarly, for implants placed in a delayed approach and received a provisional restoration following 3–4 months of healing, convex emergence profile was associated with a higher frequency of facial mucosal surfaces exhibiting apical displacement within a year of placing the final restoration protocol (Siegenthaler et al, 2022). In the present study, only maxillary premolars were included, and mucosa measurements were initiated at different time points (implant placement vs. crown placement).…”

Contour angle and peri‐implant tissue height: Two interrelated features of the implant supracrestal complex

“…At the same time, cross-sectional studies (Katafuchi et al, 2018;Majzoub et al, 2021;Yi et al, 2020) have suggested that overcontouring of the prosthesis more than 30°as it appears in peri-apical radiographs is correlated with an increased risk for peri-implantitis in bone-level implants. Finally, the convexity of the prosthesis profile has been correlated with increased recession (Siegenthaler et al, 2022), marginal bone loss (Valente et al, 2020), and when combined with overcontouring, peri-implantitis (Yi et al, 2020).…”