Usefulness of subtraction thermography in the evaluation of blood vessels and lymphatic vessels in the dental pulp.

Purpose: Caries or iatrogenic thermal trauma of the teeth have a significant impact on the dental pulp structure connected with stimulation of angiogenesis and lymphangiogenesis. Therefore, the aim of the study was to identify the difference in the rate of heat dissipation by vessels present in the dental pulp. Methods: Freshly extracted healthy (n = 10) and carious (n = 14) molars and premolars were cut on a diamond saw and subjected to active thermographic examination and then subjected to lymphoscintigraphy and X-ray examination. The tooth samples were heated uniformly to 40 ± 0.5 °C. A thermal imaging camera with a resolution of 640 × 320 pixels was used to record the sequence of thermograms during free cooling. Due to the different volume of teeth and different surface conditions of the examined teeth (color, roughness) and the related different radiation emissivity, the changes in the temperature (ΔT) of the tooth cross-section surface were analyzed using the subtractive method within 120 seconds from the switching off of the thermal impulse (heating). Results: Thermographic examination of healthy and cariously changed teeth revealed areas of increased tissue fluid flow combined with heat release, which may indirectly indicate the existence of vessels in these areas. On a thermal imaging camera, variations in the rate of heating or cooling across several cross-sectional sections of the same tooth indicate changes in the dental structure's density. Conclusions: In caries-affected teeth, intracanalicular fluid flows are different than those of healthy teeth. Therefore, it can be concluded that the pulp vessels enabling circulation of body fluids - blood and lymphatic - increases with the intensity of inflammation. Maintaining the homeostasis of the dental pulp depends heavily on the circulation of bodily fluids within the dental organ.