Effects of STAMP Techniques and Conventional Carving on Marginal Adaptation of Class I Composite Resin Restorations: An In Vitro Study.

Background: Accurate reproduction of occlusal anatomy is a critical determinant of the clinical performance of posterior composite restorations. The present study compares marginal adaptation in Class I composite restorations completed using a Kool-Dam STAMP, a flowable-composite STAMP, or conventional hand-carving techniques. Methods: Sixty extracted caries-free molars were randomly allocated to three experimental groups (n = 20). Two fixed marginal sites per tooth (mesial and distal) were measured at four measurement time points: immediately after restoration, before thermocycling, and after 10,000, 30,000, and 50,000 cumulative thermal cycles (5 °C/55 °C; 20 s dwell time). The two site-level values were averaged within each tooth for the primary analysis. A linear mixed-effects model included technique, measurement time point, and the technique-by-time-point interaction, with a random intercept for tooth. Results: No significant interaction was observed between restorative technique and measurement time point, indicating that changes in marginal gap over time were not statistically significant among the three techniques (likelihood-ratio χ2(6) = 1.43, p = 0.964). The overall effect of the technique was also not significant (χ2(2) = 1.26, p = 0.532). In contrast, marginal-gap measurements increased considerably across the four measurement time points (χ2(3) = 218.52, p < 0.001), indicating progressive increases in marginal gaps with thermal ageing. Following the Holm adjustment, no pairwise comparisons between techniques at any individual time point achieved statistical significance. Conclusions: In the present in vitro study, no statistically significant differences in marginal-gap values were detected among the Kool-Dam STAMP, flowable-composite STAMP, and conventional hand-carving techniques. The study was not designed to demonstrate equivalence or noninferiority; therefore, the absence of a statistically significant difference should not be interpreted as evidence that the techniques are equivalent. These findings suggest that the STAMP approach may be a useful technique for reproducing occlusal morphology while maintaining marginal fit. However, further clinical studies are needed to confirm its long-term performance in vivo.