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

OBJECTIVES: The aim was to evaluate peri-implant tissue levels over a 3-year period for implants connected to either convex or concave final abutments at the time of implant placement. MATERIALS AND METHODS: In this randomized, double-masked, controlled clinical study, 28 patients with one missing maxillary premolar were assigned to receive one single implant with a permanent abutment of either convex (CONVEX Group) or concave (CONCAVE Group) emergence shape at the time of implant placement. Clinical and radiographic data were collected at the time of implant placement (IP), final prosthesis delivery (PR), 12 months (FU-1), and 36 months (FU-3) following implant placement. RESULTS: At the FU-3 13 patients were available from the CONCAVE Group (n = 13) and eleven from the CONVEX Group (n = 11). The mean change in buccal peri-implant mucosa position (MP) from IP to FU-3 was -0.54 ± 0.93 mm for the CONVEX Group and - 0.53 ± 0.87 mm for CONCAVE Group (p = .98). The amount of bone remodeling above the implant platform from IP to FU-3 was -0.69 ± 0.48 mm for the CONVEX Group and -0.16 ± 0.22 mm for the CONCAVE Group (p = .005). CONCLUSION: The study failed to support the hypothesis that abutment macro-design has an effect on buccal peri-implant mucosa margin position over time

THE EFFECT OF ABUTMENT RECONNECTION AND DISCONNECTION ON PERI-IMPLANT MARGINAL BONE: A SYSTEMATIC REVIEW AND META-ANALYSIS

Objective. The aim of the present systematic review and meta-analysis was to evaluate the effect of abutment disconnection and reconnection on peri-implant marginal bone. Background. It has been reported that multiple abutment disconnections and reconnections following implant placement may compromise the peri-implant mucosal seal and may lead to increased marginal bone loss. Methods. This review was conducted according to the PRISMA guidelines for systematic reviews. An electronic search was conducted in databases including Ovid Medline, Elsevier EMBASE, and EBSCO CINAHL from January 1937 up to Oct 2015 to find clinical studies to evaluate the effect of abutment reconnection and disconnection on peri-implant marginal bone. Two reviewers independently screened titles and abstracts for potential inclusion. Meta-analyses were conducted for the primary outcome: peri-implant marginal bone level change. The mean differences of peri-implant marginal bone loss between implants received final abutments at the time of implant placement and implants submitted to multiple abutment reconnections and disconnections were estimated as the effect-size measures. Results. A total of 392 titles and abstracts were identified after de-duplicating the electronic search. 383 articles were excluded as irrelevant to the PICO question. Scrutiny of the full-text articles from the remaining 9 articles led to the exclusion of 2 studies after application of the pre-specified exclusion criteria. In total, 7 clinical studies were included in this review. All studies reported changes in periimplant marginal bone level as an outcome. Meta- analysis of seven studies showed an increased in mean (95% confidence interval) marginal bone loss of 0.19 (0.06- 0.32) mm. Conclusion. Multiple abutment reconnections and disconnections are associated with statistically significant increased marginal bone loss, when compared to final abutment placement at the time of implant surgery (one abutment one time). Grants. N/

Abutment Disconnection/Reconnection Affects Peri-implant Marginal Bone Levels: A Meta-Analysis

Purpose: Preclinical and clinical studies have shown that marginal bone loss can be secondary to repeated disconnection and reconnection of abutments that affect the peri-implant mucosal seal. The aim of this systematic review and meta-analysis was to evaluate the impact of abutment disconnections/reconnections on peri-implant marginal bone level changes. Materials and Methods: To address this question, two reviewers independently performed an electronic search of three major databases up to October 2015 complemented by manual searches. Eligible articles were selected on the basis of prespecified inclusion and exclusion criteria after a two-phase search strategy and assessed for risk of bias. A random-effects meta-analysis was performed for marginal bone loss.Results: The authors initially identified 392 titles and abstracts. After evaluation, seven controlled clinical studies were included. Qualitative assessment of the articles revealed a trend toward protective marginal bone level preservation for implants with final abutment placement (FAP) at the time of implant placement compared with implants for which there were multiple abutment placements (MAP). The FAP group exhibited a marginal bone level change ranging from 0.08 to 0.34 mm, whereas the MAP group exhibited a marginal bone level change ranging from 0.09 to 0.55 mm. Meta-analysis of the seven studies reporting on 396 implants showed significantly greater bone loss in cases of multiple abutment disconnections/reconnections. The weighted mean difference in marginal bone loss was 0.19 mm (95% confidence interval, 0.06–0.32 mm), favoring bone preservation in the FAP group. Conclusion: Within the limitations of this meta-analysis, abutment disconnection and reconnection significantly affected peri-implant marginal bone levels. These findings pave the way for revisiting current restorative protocols at the restorative treatment planning stage to prevent incipient marginal bone loss.</p