The study hypothesizes that masticatory laterality caused by acute apical periodontitis pain result in muscle asymmetry. Furthermore, it posits that successful root canal treatment, by restoring normal bilateral chewing function, will reduce this asymmetry, as evidenced by ultrasonographic measurements of the masseter and anterior temporal muscles.The main question it aims to answer is:

Can bilateral chewing function be restored after root canal treatment procedures in patients with masticatory laterality due to painful teeth due to acute apical periodontitis?

Inclusion Criteria

• Patients with masticatory laterality due to tooth pain for at least 30 days
• First and second maxillary or mandibular molars with acute apical periodontitis due to deep caries
• Teeth with moderate or severe pain according to the VAS (no pain (0 mm), mild pain (1-3 mm), moderate pain (4-6 mm), and severe pain (7-10 mm))
• Teeth that responded positively to percussion test
• Teeth without periapical pathosis were included in the study. Exclusion Criteria
• Systemic conditions affecting muscle structure or function, such as neuromuscular or endocrine disorders.
• Non-endodontic odontogenic pain.
• Prior endodontic treatment of the relevant tooth within the last 30 days.
• History of trauma or surgery to the head, face, or teeth within the last six months.
• Severe communication disorders or psychological issues.
• Inability to complete treatment in a single visit due to exudation or bleeding
• Patients with masticatory laterality due to missing tooth on any side of the dental arch
• Patients who have painful teeth in opposite sides of the dental arch
• TMD patients were excluded from the study.

•. 20 systemically healthy patients (11 female, 9 male) aged 18-60 years

• Patients with masticatory laterality due to tooth pain for at least 30 days
• First and second maxillary or mandibular molars with acute apical periodontitis due to deep caries
• Teeth with moderate or severe pain according to the VAS (no pain (0 mm), mild pain (1-3 mm), moderate pain (4-6 mm), and severe pain (7-10 mm))
• Teeth that responded positively to percussion test
• Teeth without periapical pathosis