Computerized infrared thermographic imaging and pulpal blood flow: Part 1.A protocol for thermal imaging of human teeth

Aim To observe the thermographic appearance of teeth and to develop a suita ble protocol for imaging teeth in human subjects using modern thermographic imaging (TI) equipment in a thermologically controlled environment, Methodology The emissivity of enamel was investigated using an extracted in cisor tooth. A total of 12 unrestored maxillary lateral incisors in six hea lthy patients were then imaged under rubber dam after a 20-min equilibratio n period and the thermographic data analysed using a dedicated software pac kage. Recordings were made from standardized gingival and incisal sites on each tooth and the temperature gradient established for each tooth. Subsequ ently, a sequence of images of both maxillary central incisors in one patie nt was stored every 30 s during a 20-min equilibration period with and with out an air-conditioning unit in operation. Results For the lateral incisors there was a consistent temperature gradien t (mean 1.28 degrees C) from gingival area to incisal area and there were n o statistically significant differences between right and left sides for th e gingival site (t = 0.34, NS) or the incisal site (t = 0.62, NS). The air- conditioning unit had a rapid and profound cooling effect. With the air-con ditioning disabled there was a mean tooth surface temperature increase of 1 .1 degrees C from 0 to 5 min of the equilibration period and 0.3 degrees C from 15 to 20 min. Conclusions There was no significant difference in gingival or incisal temp eratures between pairs of contralateral maxillary lateral incisors and a co nsistent temperature gradient existed from gingival to incisal areas of hea lthy maxillary lateral incisor teeth. The protocol described is suitable fo r TI of vital teeth. However, TI measured tooth surface temperature only wh ich was extremely sensitive to air currents. A 15-min acclimatization perio d under rubber dam was adequate to allow stable tooth surface temperature m easurement.