[A comparative study of the upper airway changes of idiopathic condylar resorption and anterior open bite patients after bilateral temporomandibular joint prostheses surgery and bimaxillary orthognathic surgery].

Objective: To evaluate the 2-dimension and 3-dimension changes of upper airway of patients who were diagnosed with idiopathic condylar resorption (ICR) and anterior open bite as well as received bilateral temporomandibular joint (TMJ) prostheses replacement or bimaxillary orthognathic surgery. Methods: This study is a retrospective study. Seventeen patients diagnosed as ICR and anterior open bite in Department of Orthognathic and TMJ surgery, West China Hospital of Sichuan University were selected (January 2018 to December 2021) and divided into bilateral TMJ protheses replacement group (group R, n=8) and orthognathic group (group O, n=9), according to which surgery they have performed. In order to compare variation of upper airway before and after surgery in different dimensions and sections within the same group or between groups, Spiral computed tomography data were obtained before (1 month) and after operation (10 to 12 months) to measure the total volume of airway (VT), the maximum sagittal area (MSA), the maximum cross-sectional area (MACA), the minimum cross-sectional area (MICA), the area of the most posterior plane(PPA), the area of soft-palate plane (SPA), the area of the most posterior point of tongue base plane (PTA), the area of the root of epiglottis plane (EA), the oropharyngeal airway volume (VO), the glossopharyngeal airway volume (VG) and the laryngeal airway volume (VL). Wilcoxon signed-rank test were used to complete statistical analyses for VO (T2),SPA (T2),ΔMSA,ΔMACA in group R as well as PTA (T1),EA (T2) in group O. Statistical analyses of other items were performed with student's t test. Results: VT, VO, VG, VL, MSA, MACA, MIC, PPA, PTA and EA of group R (T2) were significantly increased after TMJ prosthesis with Lefort I osteotomy (P<0.05). Meanwhile the VT, VO, VG, MSA, MACA, MICA, PPA and SPA of group O (T2) were significantly increased (P<0.05). There were significant difference in ΔVT and ΔVL between group R [(6 854.80±3 197.82) mm3, (2 252.85±1 527.96) mm3] and group O [(3 367.91±3 124.62) mm3, (413.21±1 244.44) mm3](t=2.27, P=0.038; t=2.74, P=0.015). Conclusions: Bilateral temporomandibular joint (TMJ) prostheses replacement and bimaxillary orthognathic surgery can both enlarge the areas and volumes of upper airway in patients who suffer from ICR and anterior open bite. Compared with bimaxillary orthognathic surgery, bilateral temporomandibular joint prostheses replacement plays a more pronounced role in enlargement and reconstruction of middle-inferior section of upper airway.