Mapping the horizontal thermal distribution profile of composite resins during polymerization using real-time infrared thermography

Purpose: This study aimed to establish a technical protocol using real-time infrared thermography to visualize and analyze the horizontal thermal distribution profiles and spatial thermal gradients of composite resins during photopolymerization.The study evaluated and compared the polymerization heat of conventional and bulk-fill resins across various thicknesses from the perspective of spatial thermal gradients.Materials and Methods: Specimens of a flowable resin (G-aenial Flo) and a bulk-fill resin (SDR) were prepared in thicknesses from 0.5 to 5.0 mm.During light-curing with a high-intensity light-emitting diode curing light unit, thermal data were collected in real-time along a linear axis extending from the center of maximum temperature rise to the periphery.Due to the use of a single specimen per condition, the results were interpreted descriptively.Results: In all specimens, the peak temperature decreased as the distance from the center increased.SDR exhibited faster thermal response and superior spatial thermal homogeneity than G-aenial Flo across all thicknesses.Notably, SDR exhibited sustained thermal activity up to 5.0 mm, whereas the conventional flowable resin showed significantly reduced lateral thermal response at thicknesses beyond 2.5 mm. Conclusion:Real-time infrared thermography is an effective tool for analyzing the spatiotemporal dynamics and horizontal thermal profiles of composite resins.The spatial thermal analysis in this study provides critical technical insights for clinicians in selecting appropriate materials and layering techniques for deep cavity restorations.These thermographic findings represent an indirect assessment of polymerization behavior and do not directly indicate the degree of conversion.(