Use of Thermal Imaging for Detection of Early Pulpal Inflammation After Deep Caries

Abstract

Background: Early diagnosis of pulpal involvement in deep carious teeth remains challenging because conventional pulp sensibility tests primarily assess neural response rather than vascular or inflammatory change. Dynamic infrared thermal imaging may provide a non-invasive adjunct by recording post-stimulation temperature recovery patterns that reflect altered tooth thermal behavior.  Objective: To evaluate whether thermal imaging demonstrates altered recovery patterns in permanent teeth with deep caries and whether these findings correspond with routine cold test and electric pulp test responses.  Methods: This hospital-based diagnostic technology study included 46 patients with one deeply carious permanent tooth each. After clinical and radiographic assessment, baseline thermal images were recorded under standardized conditions, followed by controlled cold stimulation and serial thermal imaging to assess post-stimulation recovery. Where available, corresponding control teeth were compared. Cold testing and electric pulp testing were performed after thermal recording. Main variables included recovery time, temperature difference, cold-test response, and electric pulp test pattern.  Results: Deep carious teeth showed longer mean thermal recovery time than control teeth, with recovery increasing from 11.2 seconds to 18.4 seconds. Mean temperature difference increased progressively across cold-test categories: 0.6°C in normal response, 1.1°C in exaggerated but non-lingering response, 1.8°C in lingering response, and 2.2°C in no response. Longer recovery time also showed a positive clinical pattern with higher electric pulp test readings.  Conclusion: Dynamic thermal imaging demonstrated delayed recovery and greater thermal alteration in deep carious teeth, with changes increasing across abnormal pulp sensibility responses. Thermal imaging may serve as a rapid, painless, and non-invasive adjunct for early pulpal assessment in clinically uncertain deep caries cases