Evaluation of the peri-implant tissues in the esthetic zone with prefabricated titanium or zirconia abutments: A randomized controlled clinical trial with a minimum follow-up of 7 years

Statement of problem. Long-term clinical studies are lacking on the influence of the type of abutment, titanium or zirconia, on peri-implant tissues. Purpose. The purpose of this randomized clinical trial was to evaluate peri-implant tissues with titanium or zirconia abutments. Material and methods. A total of 26 single-tooth implant-supported prostheses in 14 participants were analyzed. They received either a titanium abutment with a metal-ceramic crown (TAG) or a zirconia abutment with a ceramic crown (ZAG). Data were collected immediately, at 5 months, and at a minimum of 7 years after crown delivery. The success rate, plaque and bleeding indexes, bleeding on probing, white and pink esthetic scores, and the relationships of the gingival phenotype with the pink esthetic score were analyzed. Statistical analyses were conducted with the t test for paired and independent data (a=.05). Results. The mean follow-up time was 95.2 +/- 2.6 months, showing an implant success rate of 96.7%. No statistically significant differences were found between TAG and ZAG among the time intervals evaluated for plaque or bleeding indexes (P>.05). A statistically significant difference was found for peri-implant probing depths in the mid-buccal sites between the groups at all the time intervals evaluated (TAG, P=.008; ZAG, P=.021): TAG showed an increase between 5 months (3.65 +/- 0.93 mm) and over 7 years (4.47 +/- 1.32 mm); and ZAG showed a reduction (5 months=5.22 +/- 1.71 mm; over 7 years=4.25 +/- 1.28 mm) in values. For the pink (PES) and white esthetic score (WES), ZAG (PES: immediately=6.33 +/- 1.41; 5 months=7.44 +/- 1.81; over 7 years=8.25 +/- 1.03; WES: immediately=7.67 +/- 1.50; over 7 years=8.38 +/- 0.74) showed higher mean values than TAG (PES: immediately=5.94 +/- 2.35; 5 months=6.53 +/- 2.15; over 7 years=7.44 +/- 1.81; WES: immediately=7.00 +/- 1.17; over 7 years=8.35 +/- 1.27) (P<.05). Statistically significant differences were found for gingival phenotype and for PES in TAG (P=.031), and the participants with thick phenotype showed higher PES in the 3 time intervals studied. Conclusions. Zirconia abutments exhibited better results than titanium abutments in terms of the peri-implant tissues. Moreover, in those with a thin phenotype, zirconia provided improved gingival esthetics. (J Prosthet Dent 2023;129:573-81)