In Vivo Wear Analysis of Leucite-Reinforced Ceramic Inlays/Onlays After 14 Years

Abstract

Material wear significantly impacts the clinical success and longevity of dental ceramic restorations. This in vivo study aimed to assess the wear behavior of IPS Empress^® glass-ceramic inlays and onlays over 14 years, considering the influence of different antagonist materials. Fifty-four indirect restorations of 21 patients were available for comprehensive wear analysis, with complete follow-up data for up to 14 years. Three-dimensional measurements relied on digitized epoxy resin models produced immediately post-insertion (baseline) and subsequently at 2, 4, and 14 years. The occlusal region on the baseline model was delineated for comparative analysis. Three-dimensional superimpositions with models from subsequent time points were executed to assess wear in terms of average linear wear and volumetric loss. Statistical analyses were conducted in R (version 4.4.1), employing Mann-Whitney U tests (material comparisons) and Wilcoxon signed rank tests (time point comparisons), with a significance threshold of p ≤ 0.05. During the entire study period, an increase in wear was observed at each assessment interval, gradually stabilizing over time. Significant differences in substance loss were found between the follow-up time points, both for mean (-0.536 ± 0.249 mm after 14a) and integrated distance (-18,935 ± 11,711 mm³ after 14a). In addition, significantly higher wear was observed after 14 years with gold as antagonist compared to other materials (p ≤ 0.03). The wear behavior of IPS Empress^® ceramics demonstrates clinically acceptable long-term outcomes, with abrasion characteristics exhibiting stabilization over time.

Keywords: all-ceramic restorations; ceramic inlays/onlays; long-term clinical investigation; occlusal interactions; wear behavior; wear of glass-ceramic.

Figure 1

Pie chart of the antagonist distribution in percentage.

Figure 2

Clinical and virtual 3D visualization of occlusal wear over a 14-year period. Series (1a–1d): Clinical situations in an occlusal view. Series (2): Corresponding 3D surface models. (2a): Baseline model with defined region of interest (ROI). (2b–2d): Superimpositions of follow-up models with baseline. Color-coded distance maps illustrate material loss, with blue denoting wear and green indicating areas with no or almost no surface loss. Series (3): Color-coded scale bar to quantify surface changes.

Figure 3

Flowchart illustrating the study design.

Figure 4

Boxplot diagrams depicting the occlusal wear of the ceramic restoration in terms of average surface loss (mean distance) (A) and volume decrease (integrate distance) (B) after 2, 4, and 14 years. The black rhombus symbols indicate outliers.