Assessment of oral trigeminal sensitivity in humans

The aim of this prospective study was to establish a clinical test for the assessment of oral trigeminal sensitivity. Capsaicin-impregnated filter paper strips (five concentrations: 0.0001-1%) were used to measure trigeminal thresholds. The strips were placed on the anterior tongue for 10 s. Subjects were asked to report the onset of any sensory perception, quality and duration of sensory perception. Thresholds were estimated in two ways: (1) threshold (THR1) related to sensory perception and (2) intensity related threshold (THR2). The test was applied to 63 healthy subjects (mean age 40 years; 34 women, 29 men). For whole-mouth testing with capsaicin, a small but significant correlation was found between THR1 and THR2 (r (63) = 0.41). Coefficients of correlation between test and re-test were r (30) = 0.60 for THR1 and r (30) = 0.78 THR2. Neither THR1 nor THR2 indicated either side or sex-related differences. Age-related differences were only found in THR2 scores, which were lower in young subjects (<40 years). Reliable assessment of intraoral trigeminal sensitivity appears to be possible using the presently described technique.