CPT code 21116 denotes injection of contrast material into the temporomandibular joint for TMJ arthrography, a targeted diagnostic procedure used to evaluate joint anatomy and pathology. Nationally, this code matters because it identifies a specialized imaging technique often used when noninvasive imaging is inconclusive, with implications for care pathways in dental, oral maxillofacial, and otolaryngology practices. Key payers in the national landscape include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context for TMJ arthrography, the typical sites of service, and the payer mix relevant to coverage discussions. The publication also summarizes benchmark information where available, highlights recent policy and coding considerations affecting claims submission, and clarifies clinical scenarios that commonly prompt use of this code. Data not available in the input is noted where relevant. This summary equips billing managers, clinicians, and policy analysts with a clear description of the procedure and the payer landscape to inform coding, billing, and utilization review activities.