Tactile trigeminal region acuity in temporomandibular disorders: A reliability and cross-sectional study

Two-point discrimination (2-PD) is a valuable test for measuring tactile acuity that provides relevant information about cortical reorganisation and somatosensory function.

The main objectives of the present study were to assess intra- and interexaminer reliability of the 2-PD test in the trigeminal region in asymptomatic individuals and only intra-examiner reliability in patients with temporomandibular disorders (TMD). The secondary objective was to observe the correlations of the 2-PD test with regard to pain intensity and psychological and disability variables.

Intra- and interexaminer reliability of 2-PD in the trigeminal region was assessed in 40 asymptomatic individuals and 54 patients with TMD. Each clinician received training in the assessment of 2-PD using an esthesiometer and following a standardised protocol for the three branches of trigeminal nerve.

In the asymptomatic participants, interexaminer (intra-class correlation coefficient (ICC .64-.88) and test-retest (ICC .70-.87) values were obtained. Given similar test-retest values were shown in the group of patients with TMD (ICC .72-.86), the reliability were considered good-moderate. Statistically significant differences (P < .001) were obtained between the asymptomatic participants and the patients with TMD regarding the mean values from trials of the three trigeminal branch measurements, with a large effect size.

Reliability of the 2-PD test was considered good-moderate. Patients with TMD showed greater distances in the 2-PD test, suggesting that tactile acuity in the trigeminal region is impaired in patients with TMD. Assessment of tactile acuity with 2-PD test in patients with TMD should be considered clinically.