Color stability and wear behavior of polished and glazed lithium aluminium disilicate hybrid abutment crowns : a 3-year clinical pilot study

Abstract

Objectives: To evaluate the influence of two surface finishing procedures—mechanical polishing and glaze firing—on the color stability and wear behavior of lithium aluminium disilicate (LAD) hybrid abutment crowns over a three-year clinical observation period. Methods: Twenty-four patients requiring 34 implant-supported single crowns were included in this prospective clinical study. LAD abutment crowns were fabricated using n!ce ceramic and a CAD/CAM workflow and finished either by mechanical polishing (P, n = 17) or glaze firing (G, n = 17). After insertion as well as after one and three years (P: n = 9, G: n = 9) of clinical use color measurements were performed using spectrophotometry, and color differences (ΔE00) were calculated. Wear was assessed by digital surface comparison of baseline and the two follow-up scans using three-dimensional analysis software. Reference teeth (R) were defined and evaluated comparable to the P and F groups. Biological and technical complications were recorded throughout the observation period. Results: Color deviations increased over time in all groups (P, G, R). After three years, G showed lower mean color differences (ΔE00 ≈ 2.77) compared with F (ΔE00 ≈ 5.40), although the difference was not statistically significant. No significant differences in vertical height loss were observed between P and G. One adhesive fracture occurred both in the P and G group, five crowns (P: n = 3, G: n = 2) developed periimplantitis. Conclusions: Both polishing and glazing resulted in comparable clinical outcomes regarding color stability, wear behavior, and complication rates. Clinical significance: Both finishing protocols might be a reliable option for LAD hybrid abutment crowns.