Computerized infrared thermographic imaging and pulpal blood flow: Part 2.Rewarming of healthy human teeth following a controlled cold stimulus

Aim To investigate the rewarming pattern and rewarming rate of clinically h ealthy teeth following a controlled cold stimulus using TI techniques. Methodology A controlled cold stimulus was developed using an air stream at 20 degrees C, Gingival and incisal sites on 12 healthy maxillary lateral i ncisors in six patients were imaged under rubber dam following 20 s cooling . Images were captured at 10 s intervals during a 3-min rewarming period an d the data used to construct graphs of the rewarming rate. Log transformati on of the data was used to produce best fit' straight line graphs. Linear r egression analysis was used to examine three variables, viz. the side of th e mouth (right or left). the site of measurement (gingival or incisal) and the phase of rewarming (early 0-90 s, late 91-180 s). Results The mean temperature change (Delta t degrees C) during rewarming wa s 8.5 degrees C (SD 1.0 degrees C) fur gingival sites and 7.2 degrees C (SD 1.1 degrees C) for incisal sites, The slops of the 'best fit' straight lin e data enabled a rewarming index to be calculated for each site on each too th, Linear regression analysis showed that the phase of rewarming was highl y significant but the: other variables were not, A one-way ANOVA showed no significant differences between or within groups. Conclusions Three min is an appropriate time to record rewarming of teeth c ooled for 20 s with an airstream at 20 degrees C, The side or site used to record surface temperatures using this technique is not significant. Rewarm ing is exponential and log transformation of the data produces a well-fitti ng straight line graph. The slope of this line provides a rewarming index w hich should enable comparison of TI and laser Doppler flowmetry in determin ing pulpal blood now as a measure of tooth vitality.