The purpose of this study was to determine whether botulinum toxin A (BTX-A) was efficacious for the treatment of chronic moderate to severe jaw muscle pain in females. This was a randomized double-blind, placebo-controlled crossover trial of BTX-A. Twenty five units injected into each temporalis muscle and 50U injected into each masseter muscle using three sites per muscle with 0.2cm3 per site. Data were collected at baseline, 8, 16, 24 weeks, with crossover occurring at 16 weeks. Primary outcome variables were pain intensity and unpleasantness, measured by horizontal visual analog scale (VAS). Secondary outcome variables were maximum interincisal opening without and irrespective of pain, muscle palpation tenderness (12 points), and four general questions. Fifteen female patients were enrolled (18-45 years), but only ten completed the trial. Of those who finished, no statistically significant difference was found in pain intensity (P=0.10), unpleasantness (P=0.40), palpation muscle tenderness (P=0.91), or the three general questions (P=0.64, P=0.66, P=0.67). Statistical significance was achieved for maximum opening without pain (P=0.02) and irrespective of pain (P=0.005) with the BTX-A arm having a relative decreased opening. No statistically significant difference was observed in any outcome measures except maximum opening, which showed BTX-A patient opening less wide than placebo. The results do not support the use of BTX-A in the treatment of moderate to severe jaw muscle pain in this patient population.
Bibliographical noteFunding Information:
Financial support for this research was received from the University of Alberta Fund for Dentistry (#2000-06), Allergan Canada (donated treatment drug and funds for pharmacy support) and McNeil Pharmaceutics (donated breakthrough analgesic). We would like to thank Dr Art Miller, Department of Growth and Development UCSF, for his insightful comments and assistance in the manuscript preparation.
- Botulinum toxins
- Facial pain
- Masticatory muscles
- Randomized controlled trials