Accuracy and reliability of thermal threshold measurement in the chin using heat flux technique

BackgroundNeurosensory disturbance (NSD) occasionally develops in the chin following dental treatments, and evaluation of the involved nerve damage is important for treatment. The thermal-threshold test is a method of evaluating nerve sensations, but it is not widely used because its accuracy and reliability have not yet been determined.PurposeThis study aimed to determine the accuracy and reliability of thermal-threshold measurement of the chin by using the heat-flux technique.Materials and methodsThe subjects were 19 healthy volunteers (7 women, 12 men), aged 21 to 36 years (mean age ± SD, 27.2 ± 4.5 years). The thermal thresholds, including the warm and cold heat-flux thresholds (WHF and CHF, respectively) were measured on the chin, forehead, and neck by using a thermostimulator. To evaluate test-retest reliability, we measured the thermal thresholds on 3 different days (days 1, 3, and 7).ResultsThe WHF and CHF of the right chin were 460 ± 165 W/m2 (mean ± SD W/m2) and 589 ± 133 W/m2, respectively, and those of the left chin were 446 ± 112 W/m2 and 576 ± 147 W/m2, respectively. The thermal thresholds of the right and left chin were significantly correlated (R = 0.89, P < .001). Thermal-threshold measurement was more accurate in the case of the chin than in the case of the neck. The thermal thresholds measured over the 3 days varied very little (intraclass correlation coefficient, 0.80-0.81), indicating high test-retest reliability.ConclusionThe heat-flux technique is accurate and highly reliable. Therefore, it may be a useful method for determining the thermal threshold of the chin.