Infrared thermographic emissivity of heat generated during enamel versus dentin preparation: a linear regression...

The preparation of dental cavities generates heat through friction that can affect the internal structure of the tooth, especially the dentin. This study explores the infrared thermal emissivity in enamel and dentin, with and without irrigation, using different types of rotary burs to identify safer practices during dental procedures. An in vitro experimental study was developed following the CRIS Guidelines in the Orthodontics Laboratory at UNFV. Human premolars extracted for orthodontic reasons (n = 20 per group) were used and randomly assigned to conditions with or without irrigation in the enamel and dentin. The cavities were prepared with round and cylindrical burs using a KaVo high-speed turbine. The surface temperatures were recorded with a Fluke TiS55 + thermal imaging camera, calibrated and focused at 1 m. Statistical analysis included Student's t-tests and multiple linear regression models in Stata 17.0. Dentin without the use of irrigation had a higher thermal emissivity than enamel (up to 39.5 °C compared to enamel 32.05 °C), indicating that dentin has greater sensitivity to friction. Irrigation was able to reduce the temperature to approximately 22 °C in both tissues with no significant difference between bur types. The statistical model demonstrated that for every 1 °C increase in enamel temperature, dentin temperature rose by an additional 0.40 °C (p < 0.05). In contrast, variations in bur geometry did not exert a significant influence on dentin heat generation, underscoring that tissue response was primarily driven by thermal transfer rather than instrument design. Irrigation demonstrated strong efficacy as a thermal regulator, significantly reducing dentin temperature during cavity preparation. These results underscore the critical role of irrigation in preserving the integrity of internal dental tissues-particularly in clinical scenarios where direct cooling is not applied.