The influence of abutment macro-design on clinical and radiographic peri-implant tissue changes for guided, placed, and restored implants: A 1-year randomized controlled trial.

Abstract

The aim was to evaluate the peri-implant tissue levels over a 1-year period for implants connected to either convex or concave final abutments at the time of implant placement. In this randomized, double masked, controlled clinical study, twenty-eight patients with one missing maxillary premolar were allocated to receive one single implant with abutment of either convex (CX Group) or concave (CV Group) emergence shape. A block randomization sequence was used to allocate treatments. Opaque sealed randomization envelopes were used for allocation concealment. All implants received final abutments and interim crowns at implant placement and permanent crowns following 3months. Clinical and radiographic data were collected at the time of implant placement (IP), final prosthesis delivery (PR), and 12months following implant placement (FU-1). One patient from the CX Group (n=13) dropped out from the study and for one patient from CV Group (n=13), the implant failed to integrate. The mean change in peri-implant buccal mucosa position (MP) from IP to FU-1 was -0.76±0.72mm for CX Group and -0.69±0.89mm for CV Group (p=0.8). The amount of bone remodeling above the implant platform from IP to FU-1 was -0.66±0.46mm for the CX Group and -0.24±0.25mm for the CV Group (p=0.007). Buccal bone thickness was significantly correlated with the amount of buccal MP change from IP to FU-1 (r=0.4, p=0.038). The study failed to support the hypothesis that abutment macro-design has an effect on peri-implant mucosa margin position changes over time.