Assessment of Masseter Muscle With Ultrasonography

Inclusion Criteria: Systemically healthy adults aged 18-65 years (American Society of Anesthesiologists Class I) Diagnosis of acute apical periodontitis Presence of at least four posterior occlusal units (one premolar pair counted as one unit; one molar pair counted as two units) Age ≥18 years Absence of maxillofacial pathology or systemic disease No history of temporomandibular joint or masticatory muscle disorders No complaints of dysphoni No diagnosed muscular disorders Exclusion Criteria: Presence of systemic disease Current use of any medication Fewer than 20 natural teeth Presence of prosthetic restorations (single crowns, fixed dental prostheses, or removable prostheses) Dental implant restorations History of periodontal treatment within the previous year Diagnosis of symptomatic pulpitis Pregnancy Smoking Unilateral edentulism