Introduction:
Pressure pain threshold has been quantified by using a gold standard algometer in patients with bruxism. However, the expense associated with quantifying pressure pain threshold to detect trigger points with a gold standard algometer precludes its use in the clinic. This study aimed to measure the reliability and validity of the more accessible Egyptian algometer for pressure pain threshold evaluation in patients with bruxism.

Methods:
A descriptive repeated-measures study was performed among 100 participants with bruxism. Pressure pain threshold values were collected from the left temporalis, right temporalis, left masseter, and right masseter muscles with the participants sitting. Pressure pain thresholds were assessed over 2 sessions separated by a 1-week interval.

Results:
Intraclass correlation coefficient (ICC) determined the intra-rater reliability and Pearson correlation analysis determined the validity of the Egyptian algometer. ICC equalled 0.878, 0.785, 0.896, and 0.903 for the right masseter, left masseter, right temporalis, and left temporalis muscles, respectively. The standard error of measurement ranged from 0.24 to 0.5, the minimal detectable difference ranged from 0.66 to 1.41, ICC ranged from 0.785 to 0.903. Pearson correlation values were 0.673, 0.670, 0.408, and 0.705 for the right masseter, left masseter, right temporalis, and left temporalis muscles, respectively.

Conclusions:
High ICCs indicated a strong agreement between the measurement systems, suggesting that the Egyptian algometer is a reliable and valid device for quantification of pressure pain threshold in patients with bruxism.