Three-Dimensional Evaluation of Positional Changes in Single-Unit CAD/CAM Restorations Following Cementation -An Analysis of an On-going RCT Cohort.

OBJECTIVE: To compare the three-dimensional (3D) position of digitally designed single-unit restorations with their clinical intraoral position after cementation. MATERIAL AND METHOD: This study is part of an on-going randomized clinical trial evaluating the success of indirect restorations - onlays and crowns - fabricated from different machinable materials: aluminosilicate glass ceramics (N!ce, Straumann), hybrid ceramics (VITA ENAMIC, VITA Zahnfabrik), and lithium disilicate (IPS e.max CAD, Ivoclar Vivadent). A retrospective digital analysis was performed by comparing original CAD design files with intraoral scans obtained after definitive cementation. The sample included single-unit restorations from 52 patients, with 13 treated at the University and 39 treated in a specialized private practice. Following cementation and occlusal adjustments, quadrant scans were acquired using two intraoral scanners (CEREC Omnicam, Sirona; and TRIOS 3, 3Shape). Scan data were exported as STL files, superimposed with the corresponding digital designs, and analysed using GOM Inspect software. RESULTS: No significant differences in trueness were found among restoration types or materials. Mean deviations were 120µm ± 38µm for aluminosilicate glass ceramics, 129µm ± 28µm for hybrid ceramics, and 118µm ± 39µm for lithium disilicate. Crowns showed a tendency toward better trueness (113 µm ± 32µm) than onlays (132µm ± 36µm; p=0.056). Precision analysis also revealed no significant differences between groups. CONCLUSIONS: Within the study limitations, both restoration type and material demonstrated comparable and minimal 3D deviations, supporting satisfactory accuracy of a fully digital workflow for single-unit indirect restorations.