Thermal Observation of Tooth Transfer Heat

Objectives: All tissue with a temperature above absolute zero emits infrared radiation - the wavelength and quantity of which depends on tissue characteristics and environmental conditions.
The primary objective was to visually characterise the internal surfaces of human enamel and dentine tooth sections, following the transfer of heat with a thermal camera.
The secondary objective was to assess the diagnostic potential of heat-transfer for demineralisation and future vitality-testing of teeth.

Methods: Two ethically-sourced human third-molars, one sound and one demineralised, were sliced bucco-lingually into 1mm-thick sections (Accutom-5), polished, measured with a digital micrometer and stored in distilled water. Pre- and post-slice photographs and radiographs were taken. A thermally-stable environment (22^oC±0.1^oC) was achieved with macro- and micro-controlled thermal sensors. Tooth-slices were placed on a copper baseplate (0.5mm) with a thermal pad, and cooled on an ice-block. Activation of the thermal camera (FLIR SC305) recorded a heat transfer sequence at nine frames per second with ThermaCAM Researcher Professional 2.10 Software when moved to a hotplate (37^oC), to reach thermal equilibrium.
Heat-transfer data was processed in Microsoft Excel and a unique MatLab Programme, to produce original images according to frame-number and characteristic time of the heating curve.

Results: Thermal equilibrium was reached within three minutes for all tooth-slices. Heat-transfer images characterise enamel and dentine within 1 frame, with the best contrast and resolution seen at 9 frames (1 second). Demineralised enamel and dentine was differentiated within the same time-line.
The characteristic time-curve successfully distinguished tissue-type and demineralisation.
Conclusions: This innovative imagery of heat-transfer data has enabled visualisation of enamel and dentine of the tooth-slices and shows diagnostic capability for demineralisation. This methodology will be translated for tooth vitality in-vivo.