BMC Oral Health (Apr 2025)
Marginal and internal adaptation and absolute marginal discrepancy of 3D-printed, milled, and prefabricated crowns for primary molar teeth: an in vitro comparative study
Abstract
Abstract Background The quality of marginal and internal adaptation plays a crucial role in the clinical longevity of pediatric crowns. This study aimed to evaluate the effect of restoration type (3D-printed, milled, and prefabricated) on the marginal and internal adaptation and absolute marginal discrepancy (AMD) values of crowns for primary molar teeth. Methods Three restoration groups were created: 3D-printed resin, milled resin-matrix ceramic, and prefabricated zirconia crowns (n = 10 per group). A typodont tooth was prepared according to the guidelines for prefabricated zirconia crowns and scanned to design restorations. 3D-printed and milled crowns were fabricated from the same design. All crowns were cemented on standardized 3D-printed resin dies with self-adhesive resin cement. Marginal and internal adaptation and AMD values were evaluated using micro-computed tomography (micro-CT) at multiple measurement points. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey HSD tests, with statistical significance set at P < 0.05. Results The restoration type significantly influenced the marginal and internal gap and AMD values (P < 0.05). The prefabricated crown group exhibited the highest marginal gap (233.5 ± 33.4 μm) and internal gap (538.6 ± 47.4 μm). The 3D-printed group showed the highest AMD value (299.5 ± 70.2 μm). The milled group demonstrated the lowest gap values, which remained within clinically acceptable limits. Conclusions Prefabricated zirconia crowns displayed the highest marginal and internal gaps, whereas milled crowns exhibited the most favorable adaptation values within clinically acceptable limits. Given their superior adaptation, CAD-CAM-produced restorations may be a recommendable alternative for pediatric patients.
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