Comparison of the temporomandibular joint-space volume after mandibular reconstruction using patient-specific plate-positioning guides and the conventional method: a randomized controlled trial.

objectivesThis study aimed to compare pre- to postoperative changes in temporomandibular joint-space (TMJ-space) volumes after mandibular reconstruction using patient-specific plate-positioning guides (PPG) versus the conventional method (CM). MATERIALS AND

methodsThis single-center, non-blinded, randomized clinical trial included 36 adults who underwent mandibular reconstruction using pre-bent plates, allocated 1:1 to the PPG or CM groups. Preoperative and 1-week postoperative computed tomography images obtained in maximum intercuspation (habitual intercuspal position) were three-dimensionally segmented and analyzed using predefined craniomaxillofacial reference planes to quantify TMJ-space volumes, including the total, anterior-, posterior-, medial-, and lateral-compartment volumes. The primary endpoint was the absolute volume change on the operated side, and the secondary endpoints were occlusion-standardized changes. Eligibility excluded Brown classes Ic, IIc, and IVc (disarticulation defects); there were no restrictions on defect size. Paired t/Wilcoxon tests were used for within-group comparisons and Welch/U tests for between-group comparisons, with 95% CIs.

resultsAt 1 week, for absolute changes, |Δ|TSV favored PPG (PPG–CM = − 205.59 mm³; 95% CI − 360.86 to − 50.33; p = 0.012) and |Δ|LSV likewise favored PPG (PPG–CM = − 92.38 mm³; 95% CI − 183.17 to − 1.59; p = 0.046). For occlusion-standardized changes on the operated side, all |Δ|TSV (PPG–CM = − 166.12 mm³; 95% CI − 230.39 to − 73.19; p = 0.002), |Δ|PSV (PPG–CM = − 123.37 mm³; 95% CI − 211.03 to − 63.02; p = 0.003), and |Δ|LSV (PPG–CM = -71.44 mm³; 95% CI -129.92 to -12.95; p = 0.019) favored PPG, whereas no between-group differences were significant on the non-operated side. Operative time was shorter with PPG (median 120.5 vs. 160.5 min; p = 0.001).

conclusionsPPG-assisted reconstruction resulted in smaller absolute and occlusion-standardized changes in TMJ-space volumes than CM, suggesting reduced variation in joint-space geometry and more stable early postoperative condyle–fossa relationships as inferred from joint-space measurements. CLINICAL RELEVANCE: Smaller alterations in TMJ-space volumes together with greater operative efficiency suggest that PPG may help maintain more consistent early postoperative TMJ-space geometry after mandibular reconstruction; future studies incorporating direct three-dimensional analyses of condylar position and rotation are warranted.