Influence of titanium base, lithium disilicate restoration and vertical soft tissue thickness on bone stability around triangular-shaped implants: A prospective clinical trial

Abstract

Objective: To evaluate how vertical mucosal tissue thickness affects crestal bone stability around triangular-shaped bone-level implants, restored with low profile titanium bases and monolithic lithium disilicate restorations. Material and methods: Fifty-five bone-level implants of 4.3 mm diameter were evaluated in 55 patients (22 males and 34 females, mean age 48.3 ± 3.4 years) in prospective cohort study. According to vertical mucosal thickness, patients were assigned into three groups: 1 (thin, 2 mm or less), 2 (medium, 2.5 mm) and 3 (thick, 3 mm and more). Implants were placed in posterior mandible and maxilla in one-stage approach and, after integration, were restored with single screw-retained monolithic lithium disilicate crowns, using low gingival profile titanium bases. Radiographic examination was performed after implant placement and after 1-year follow-up. Crestal bone loss was registered mesially and distally, and mean value was calculated. One-way ANOVA and Tukey's HSD tests were applied; significance was set to 0.05. Results: Mean vertical tissue thickness in 1 group was 1.76 ± 0.26 mm, 2 group–2.5 mm and 3.91 ± 0.59 mm in group 3, with statistically significant difference between all groups (p < 0.001). After 1-year follow-up, implants in group 1 (thin) had 1.25 ± 0.8 mm bone loss. Implants in group 2 (medium) had 0.98 ± 0.06, while implants in group 3 (thick) lost 0.43 ± 0.37 mm of crestal bone. Tukey's HSD test showed that differences between 1/3 and 2/3 were statistically significant (p < 0.001 and p = 0.0014, respectively), while between 1 and 2 was not significant (p = 0.310). Conclusions: Significantly less bone loss occurs around triangular-shaped bone-level implants in thick mucosal tissues (≥3 mm), compared to medium or thin tissue biotype. Crestal bone loss did not differ between medium and thin tissues.