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.