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.

OBJECTIVES: 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. MATERIALS AND METHODS: 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 3 months. Clinical and radiographic data were collected at the time of implant placement (IP), final prosthesis delivery (PR), and 12 months following implant placement (FU-1). RESULTS: 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 +/- 0.72 mm for CX Group and -0.69 +/- 0.89 mm for CV Group (p = 0.8). The amount of bone remodeling above the implant platform from IP to FU-1 was -0.66 +/- 0.46 mm for the CX Group and -0.24 +/- 0.25 mm 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). CONCLUSION: The study failed to support the hypothesis that abutment macro-design has an effect on peri-implant mucosa margin position changes over time.