Comparative Evaluation of the Adaptation Accuracy of Two Commercially-Available Denture Base Resins: An In Vitro Study.

Introduction This in vitro study aimed to evaluate and compare the adaptation accuracy of two commercially available denture base polymers: visible light-cured (VLC) resin and thermoplastic resin. The specific objectives were to assess the adaptation accuracy of each material at different anatomical sites and to determine which material offered a superior fit across the denture-bearing maxillary arch. Materials and methods This cross-sectional study was conducted at the Department of Prosthodontics, Sibar Institute of Dental Sciences, Guntur, India, between June and December 2024. Forty standardized edentulous maxillary casts were fabricated using a silicone mold (Zhermack S.p.A., Badia Polesine, Italy) and Type III dental stone (Kalabhai Karson Pvt. Ltd., Mumbai, India). The samples were randomly divided into two groups of 20. Group A (n=20) used VLC resin sheets (Delta VLC, Delta Dental Solutions, Chennai, India), which were adapted to the casts using finger pressure and cured in a light-curing unit (Triad 2000, Dentsply Sirona, Charlotte, North Carolina, USA). Group B (n=20) consisted of thermoplastic denture base sheets (3A Medes, Seoul, South Korea) adapted using a vacuum-forming machine (Biostar; Scheu-Dental GmbH, Iserlohn, Germany) under consistent heat and pressure. All samples were transversely sectioned at the canine, molar, and posterior mid-palatal regions. Adaptation accuracy at nine specific points was measured using a stereomicroscope (Leica M205 C; Leica Microsystems, Wetzlar, Germany) at 20x magnification. Results Statistically significant differences were observed both within and between the groups. VLC resins demonstrated the best adaptation in the canine region (mean: 370.37 µm), whereas thermoplastic resins showed superior adaptation in the posterior mid-palatal region (mean: 310.79 µm). Overall, the thermoplastic resins exhibited significantly lower mean discrepancies (430.32 µm) than VLC resins (570.05 µm), with the greatest difference observed in the posterior mid-palatal region (p<0.001). Conclusion Thermoplastic denture base materials provided better adaptation accuracy than VLC resins, particularly in the anatomically challenging posterior regions. These findings suggest that thermoplastic resins may offer improved clinical outcomes in cases where a precision fit is essential.