Accuracy and fitness of digital light processing-fabricated resin-based permanent crowns after thermal aging

Resin-based materials fabricated using digital light processing (DLP) have received increasing attention for use in permanent dental restorations. This study investigated the accuracy and fit of DLP-fabricated resin-based permanent crowns before and after thermal aging.

A maxillary right first premolar resin tooth was scanned and digitally designed as a reference computer-aided design (CAD) model. Twenty DLP-fabricated permanent resin crowns were produced. Half of the specimens remained unaged, while the others underwent thermal aging through 10,000 cycles between 5 °C and 55 °C. To evaluate crown accuracy, trueness was assessed by comparing virtual models of the fabricated crowns to the design reference model. Precision was evaluated through inter-sample comparisons among the virtual models of the fabricated crowns. Color difference maps were generated for four distinct crown regions, and root mean square (RMS) values were calculated for each. Crown fitness was evaluated using the silicone replica method by measuring silicone thickness at four intaglio areas with a digital microscope. Data differences before and after thermal aging were analyzed using paired t-tests (α = 0.05).

Thermal aging significantly increased RMS values for external surface trueness (P < 0.001). Marginal and internal gaps remained within the clinically acceptable discrepancy threshold of 120 μm. Significant differences were observed in the marginal and occlusal gaps in both the coronal and sagittal planes after aging.

DLP-fabricated resin permanent crowns demonstrated acceptable trueness and clinically acceptable marginal and internal fitness. However, thermal aging reduced both the accuracy and fitness of these crowns.