Predisposing conditions for condylar sag after intraoral vertical ramus osteotomy

Abstract

Intraoral vertical ramus osteotomy (IVRO) is used to treat mandibular prognathism and temporomandibular disorders. However, the improvement of temporomandibular disorders after IVRO is considered to be due to the anterior and downward movement of the mandibular condyle, which may lead to condylar sag, and in the worst case, condylar luxation. In this retrospective cohort study, we examined factors potentially associated with condylar sag. Univariate analysis indicated that condylar sag was significantly associated with the following factors: magnitude of setback (P = 0.001), less than 3 mm setback (P < 0.001), presence of temporomandibular joint (TMJ) symptoms (P = 0.002), Wilkes classification (P = 0.039), occlusal cant correction ≥ 2 mm (P = 0.018), and mandibular condyle deformation (P < 0.001). Setback magnitude (P = 0.032) and TMJ symptoms (P = 0.007) remained significant in the multivariate analysis. In the receiver operating characteristic curve, the setback magnitude cut-off value for condylar sag after IVRO was 3.25 mm. Thus, the incidence of condylar sag after IVRO is increased with a smaller setback magnitude (≤ 3.25 mm) and the presence of TMJ symptoms. These factors should be evaluated by surgeons during treatment planning for IVRO to estimate condylar sag, and it may be possible to predict the risk of condylar luxation.

Changes of Temporomandibular Joint Morphology and Symptoms in Class II Malocclusion Patients With Bilateral Sagittal Split Ramous Osteotomy

“…22,23 Studies suggest that posterior condyle displacement or posterior and inferior displacement increases condyle absorption rate, and anterior and inferior displacement or inferior displacement can improve joint symptoms. 24 In the operation to maintain condylar position is an effective method for the prevention of postoperative symptoms of joint. 24 This study evaluated through CBCT images condylar changes in the location of the before and after surgery.…”

“…24 In the operation to maintain condylar position is an effective method for the prevention of postoperative symptoms of joint. 24 This study evaluated through CBCT images condylar changes in the location of the before and after surgery. It is believed that there is no obvious significance to measure the joint space in the coronal direction, 20 sagittal upward is the best way to evaluate the condylar fossa relationship.…”

“…The condyle of patients with more severe TMD is generally in the posterior position 22,23 . Studies suggest that posterior condyle displacement or posterior and inferior displacement increases condyle absorption rate, and anterior and inferior displacement or inferior displacement can improve joint symptoms 24 . In the operation to maintain condylar position is an effective method for the prevention of postoperative symptoms of joint 24 .…”