Monitoring of simulated occlusal tooth wear by objective outcome measures

Objectives: This in vitro study explored quantitative outcome measures as clinical indicators of simulated occlusal tooth wear progression. Methods: Ten sound, extracted human premolars were selected and submitted to occlusal tooth wear simulation in 0.5-mm steps (0/0.5/1.0/1.5 mm). At each step, enamel thickness on the buccal cusp tips was evaluated using cross-polarization optical coherence tomography (CP-OCT) and micro-computed tomography (mu-CT). The occlusal surface of each premolar was also scanned at each step using a 3D digital intraoral scanner, followed by morphological characterization using standard topography attributes (Slope, Relief, RFI, OPCr). Repeated measures ANOVA assessed differences in simulated wear levels for the mu-CT and CP-OCT data as well as the topography values. Correlations were also calculated between the mu-CT/CP-OCT and topography data. Results: Significant differences were observed for enamel thickness at each simulation wear stage, for both CP-OCT (p < 0.001) and mu-CT (p < 0.001), with good agreement between methods (intraclass correlation: 0.89). For topography analysis, as wear increased, the average Slope, RFI, and Relief values decreased, and average OPCr values increased, with more significant differences shown for Slope. Slope showed significant (p < 0.05) positive correlations with CP-OCT. OPCr showed significant negative correlations with mu-CT, and CP-OCT (p < 0.05). RFI and Relief were not correlated with either mu-CT or CP-OCT (p > 0.05). Conclusions: Our findings suggest the potential of PS-OCT for measuring enamel thickness changes in the cusp tips of the occlusal surface. Similarly, conventional intraoral scanners can serve effectively for monitoring overall tooth wear when combined with dental topographic analyses of resultant point clouds. Clinical significance: CP-OCT measures of enamel thickness and dental 3D topographic attributes showed potential as objective outcomes for the clinical monitoring of occlusal tooth wear. Their combination provided a comprehensive understanding of the tooth wear development process.