Effects of stamp material and restoration depth on the accuracy of direct composite resin restorations using stamp technique.

Abstract

To evaluate the effects of different stamp materials and restoration depths on the accuracy of direct composite resin restorations using stamp technique. Eighty standard resin teeth were divided into four groups based on different stamp materials: flowable composite resin (FR), vinyl polydimethyl siloxane (VPS) for bite registration (VB), VPS for impression (VI) and transparent VPS (TV). Each material group was further divided into two subgroups based on restoration depth (1 and 2 mm; n=10). Standardized Class I cavities were prepared and restored with the corresponding stamps. Pre- and post-treatment scans of each tooth were fitted using Geomagic Control X software, generating deviation distribution maps of the occlusal surface. The accuracy indicators, including mean height variation (MHV), root mean square (RMS), and proportions of height variation with different ranges (PHVrange), were recorded to evaluate the accuracy of restorations. Analysis of variance (ANOVA) were used for statistical analysis (α=0.05). The type of stamp material significantly affected all accuracy indicators, while restoration depth did not show a significant effect on any of the indicators. MHV values ranged from 29.70±5.88 μm to 63.52±9.58 μm, and RMS values ranged from 62.78±8.76 μm to 101.79±13.17 μm, displaying a trend of FR<VB<VI<TV. The FR groups had the highest PHV<0.05 mm values (72.24±3.40% for 1 mm, 71.47±8.54% for 2 mm) and the lowest PHV>0.2 mm values (0.70±0.50% for 1 mm, 0.94±0.47% for 2 mm). In contrast, the TV groups exhibited the lowest PHV<0.05 mm values (59.69±10.23% for 1 mm, 59.67±5.70% for 2 mm), while the VI groups showed the highest PHV>0.2 mm values (7.34±1.58% for 1 mm, 8.20±3.16% for 2 mm). The accuracy of direct composite resin restorations using stamp made of flowable composite resin was higher than that of all tested VPS materials, thereby reducing the need for occlusal adjustment and improving clinical efficiency. Besides, restoration depth had no significant impact on the accuracy of stamp technique, regardless of the stamp material used. The accuracy of direct composite resin restorations using stamp technique with different stamp materials varies. The flowable composite resin stamp exhibits higher accuracy compared with VPS stamps, reducing the need for occlusal adjustments.