Purpose: This study assessed the effectiveness of incobotulinum toxin type A (IBTx) for chronic myofascial pain affecting the masseter and temporal muscles.

Methods: Twenty two patients who received a diagnosis of chronic masseter and temporalis myofascial pain were evaluated by using a visual analog pain scale (VAS), digital pressure algometry, and the SF-36 Health Survey at baseline (T0), before IBTx injection. Patients were again evaluated at 2 months (T1) and 7 months (T2) after IBTx injection.

Results: VAS scores for pain significantly differed (P = 0.029, Friedman test). Post-hoc tests showed a significant reduction in pain at 2 months (T0–T1) and 7 months (T0–T2) (P = 0.011 and P = 0.028, respectively; Wilcoxon test) but not between 2 and 7 months (P = 0.676; Wilcoxon test). There was no significant difference in pressure algometry values (P = 0.385, Friedman test). Quality of life (QOL) assessment showed a significant difference (P = 0.002, Friedman test). Post-hoc tests showed a significant improvement in QOLat 2 months, but no significant difference at 7 months (P = 0.004 and P = 0.260, Wilcoxon test).

Conclusion: IBTx injection resulted in safe, effective short-term pain relief for patients with chronic facial pain affecting the masseter and temporalis muscles.