Patients with orofacial pain lasting at least 3 months. The patients will be randomly assigned to one of the two groups according to the treatment method: group I (intraoral injection) and group II (transcutaneous injection) where each patient injected Botox at each trigger point according to the treatment group by the same operator. Patients will be examined by a blinded investigator at pre- and post-injections at the following intervals: during diagnosis, 1 week, 4, and 6 weeks post-injection. The patients will be assessed using a pain score measured on a 10-point visual analog scale (VAS). The secondary outcome assessed will be measuring the quality of life in an Oral Health Impact Profile questionnaire (OHIP-14).

Inclusion Criteria:

• Definite diagnosis of myofascial pain with a referral
• the presence of one or more trigger points in the unilateral or bilateral masseter muscle -
• no history of any invasive procedures in the related masseter muscle

Exclusion Criteria:

• Factors that can cause pain in the orofacial region other than trigger points (decayed tooth, temporomandibular joint internal disorder).
• Any systemic disease that possibly affects the masticatory system such as rheumatoid arthritis and epilepsy
• pregnancy and lactation.