Comparative Evaluation of Surface Hardness of Bis-Acryl Composite and Polymethyl Methacrylate-Based Provisional Restorative Materials: An In Vitro Study.

INTRODUCTION

Provisional restorations are essential components of fixed prosthodontic treatment that provide protection, function, esthetics, and guidance during the transitional phase before definitive restorations are placed. The choice of materials for provisional restorations plays a critical role in determining their clinical effectiveness and durability. Among the numerous available materials, bis-acryl composite resins and polymethyl methacrylate (PMMA)-based acrylics are widely used. Surface hardness is a key mechanical property that directly affects a material's resistance to masticatory forces, wear, and deformation during function. This in vitro study was conducted to compare the surface hardness of three bis-acryl composite materials with that of one PMMA-based material to aid clinicians in selecting the most suitable material based on the performance characteristics.

MATERIALS AND METHODS

This in vitro study was conducted in the Department of Prosthodontics. Group 1 (n=40) used 3M Protemp 4 Temporization Material (St. Paul, MN: 3M ESPE AG), group 2 (n=40) used Dentsply Integrity Temporary Crown and Bridge Material (York, PA: Dentsply Sirona), group 3 (n=40) used Vericom Care C&B Dual-Cure Temporary Material (Anyang, South Korea: Vericom Co. Ltd.), and group 4 (n=40) used Pyrax High-Quality Cold Cure SC-10 (Roorkee, India: Pyrax Polymars). The specimens were prepared using stainless-steel molds. Each material was manipulated according to the manufacturer's instructions and cured according to recommended protocols. Vickers hardness testing was performed under a 25 g load for 15 s. Two indentations were made per specimen, and the Vickers Hardness Number (VHN) was calculated. The data were then subjected to statistical analysis.

RESULTS

Group 1 recorded the highest mean hardness (20.54±0.69 VHN), followed by group 2 with 19.80±0.47 VHN, group 3 with 18.55±1.36 VHN, and group 4 showing the lowest hardness (16.65±0.66 VHN). One-way Analysis of Variance (ANOVA) revealed statistically significant differences between all groups (p<0.01), with group 1 exhibiting the highest hardness across pairwise comparisons.

CONCLUSION

Bis-acryl composite materials demonstrated a significantly higher surface hardness than PMMA-based materials. 3M Protemp 4 showed the greatest hardness and may be best suited for long-term provisional restorations, whereas Pyrax SC-10 is more appropriate for short-term use owing to its lower mechanical strength.