Influence of Abutment Color and Mucosal Thickness on Soft Tissue Color

Zirconia (ZrO₂) and titanium nitride (TiN) implant abutments were introduced mainly for esthetic purposes, as titanium's gray color can be visible through mucosal tissues. This study was aimed at assessing whether ZrO₂ and TiN abutments could achieve better esthetics in comparison with titanium (Ti) abutments, regarding the appearance of soft tissues.

Ninety patients were included in the study. Each patient was provided with an implant (OsseoSpeed, Dentsply Implant System). A two-stage surgical technique was performed. Six months later, surgical reentry was performed. After 1 week, provisional restorations were screwed onto the implants. After 8 weeks, implant-level impressions were taken and soft tissue thickness was recorded, ranking thin (≤ 2 mm) or thick (≥ 2 mm). Patients were randomly allocated to three experimental groups, based on abutment type: (1) Ti, (2) TiN, and (3) ZrO₂. After 15 weeks, the final restorations were delivered. The mucosal area referring to each abutment was measured for color using a clinical spectrophotometer (Easyshade, VITA); color measurements of the contralateral areas referring to natural teeth were performed at the same time. The data were collected using the Commission Internationale de l'Eclairage (CIE) L*a*b* color system, and ΔE was calculated between peri-implant and contralateral soft tissues. A critical threshold of ΔE = 3.7 was selected. The chi-square test was used to identify statistically significant differences in ΔE between thin and thick mucosal tissues and among the abutment types.

Three patients were lost at follow-up. No statistically significant differences were noticed as to the abutment type (P = .966). Statistically significant differences in ΔE were recorded between thick and thin peri-implant soft tissues (P < .001). Only 2 out of 64 patients with thick soft tissues showed a ΔE higher than 3.7: 1 in the TiN group and 1 in the ZrO₂ group. All the patients with thin soft tissues reported color changes that exceeded the critical threshold.

The different abutment materials showed comparable results in terms of influence on soft tissue color. Regarding peri-implant soft tissue thickness, the influence of the tested abutments on soft tissue color became clinically relevant for values ≤ 2 mm.