EFFECT OF TMJ ARTHROCENTESIS ON ARTICULAR CAPSULAR WIDTH: AN ULTRASONOGRAPHIC STUDY

Plain-language summary

This study is designed as a prospective cohort study evaluating the effect of temporomandibular joint arthrocentesis on articular capsular width using ultrasonography. The study is being conducted at the Faculty of Dentistry, Van Yuzuncu Yil University, Turkey, in accordance with the principles of the Declaration of Helsinki. Ethical approval has been obtained from the Van Yuzuncu Yil University Clinical Research Ethics Committee (approval no. 2025/02-07, dated February 28, 2025). The study includes systemically healthy adult participants with unilateral intra-articular temporomandibular disorder who have not responded adequately to at least six months of conservative management, including medication, occlusal splint therapy, or physiotherapy. Exclusion criteria are systemic rheumatologic diseases, bony or fibrous ankylosis of the temporomandibular joint, previous open temporomandibular joint surgery, pregnancy or breastfeeding, and active infection. All participants undergo unilateral temporomandibular joint arthrocentesis performed under local anesthesia by a single experienced oral and maxillofacial surgeon. A standard two-needle technique is used, and the upper joint compartment is irrigated with 150-200 mL of sterile Ringer's lactate solution. No pharmacological agents are injected after the lavage. The contralateral, asymptomatic joint serves as an untreated control. Ultrasonographic and clinical assessments are performed at three time points: baseline before the procedure (T0), three months post-arthrocentesis (T1), and six months post-arthrocentesis (T2). The primary outcome is capsular width measured by ultrasonography. Secondary outcomes include pain intensity assessed using the visual analog scale, maximum incisal opening measured in millimeters, and lateral and protrusive mandibular movements. All ultrasonographic evaluations and clinical measurements are performed by a single oral and maxillofacial radiologist who is independent of the surgical procedure and postoperative patient management, ensuring blinding and minimizing bias. Pain scores are self-reported by patients without investigator interpretation. The sample size was calculated a priori using G\*Power software. Based on previous morphometric data, a minimum of 26 participants was required, and 27 participants were enrolled to account for potential dropouts. Statistical analyses include the Wilcoxon signed-rank test, Friedman test, and Mann-Whitney U test, with a significance level set at p \< 0.05. This study is one of the first prospective clinical trials to evaluate longitudinal changes in temporomandibular joint capsular width using ultrasonography following arthrocentesis. The study has received no external funding, and the authors declare no competing interests.

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