Effectiveness of intra-oral botulinum toxin injection in comparison to the extra-oral approach on pain and quality of life in patients with myofascial pain: a randomized clinical trial.

Objective: To evaluate and compare the effectiveness of the ultrasound-guided intra-oral and extra-oral transcutaneous injection techniques on the clinical outcome variables in patients with myofascial trigger points within the masseter muscle.

Materials and methods: This prospective randomized trial included 42 patients diagnosed with myofascial pain. Patients were randomly allocated into one of two groups based on the technique of trigger point injection: intraoral and extraoral injection technique groups. Each trigger point was injected with 0.1 ml of botulinum-A toxin guided by ultrasound. Pain intensity, mouth opening, and patient quality of life were monitored six months post-injection.

Results: The pain scores were significantly higher in the extraoral group during all follow-up assessments, whereas the MMO was considerably greater in the intraoral group up to three months of follow-up (p < 0.008). However, the difference in MMO ceased to be statistically non-significant after six months of follow-up (p = 0.927). Additionally, the patient's quality of life score was significantly higher in the intraoral group compared to the extraoral group (p < 0.001) at both the three- and six-month follow-ups.

Conclusion: The intraoral injection technique might be an effective treatment modality for myofascial trigger points in the masseter muscle. It produces pain relief, increases mouth opening, and enhances the overall quality of life compared to the extraoral injection technique.

Clinical significance: The intraoral injection technique for myofascial trigger points is more effective than the extraoral technique; it reduces the need for additional injections, saves money, and enhances patients' quality of life.

Trial registration: Clinicaltrials.gov (NCT05673655).