The aim of the present study was to identify the risk factors for aggressive condylar resorption (ACR) after orthognathic surgery.
A total of 25 female patients with osteoarthritis (OA) scheduled for orthognathic surgery were divided into two groups: those who exhibited ACR (ACR (+), n = 8) and those who did not exhibit ACR (ACR (-), n = 17) after surgery. Clinical indices were used to determine the extent of mandibular advancement, the presence of temporomandibular disorder (TMD), and relevant medical treatment histories (including the use of oral contraceptive (OC) medication. TMJ dysfunction was clinically evaluated in terms of pain, the presence of sounds (clicks or crepitus), and disc displacement, joint effusion (JE), and synovial hyperplasia (SH); these were further investigated with the aid of magnetic resonance imaging (MRI). The cephalographic findings were compared with the normal profiles of Japanese subjects.
The mean (with SD) extent of mandibular advancement was 11.4 mm (2.4) in ACR (+) and 4.1 mm (1.8) in ACR (-). The TMD medical history of ACR (+) was much more extensive than that of ACR (-); all patients in ACR (+) had a history of OC use. More patients in ACR (+) than in ACR (-) had TMJ dysfunction and disc displacement, JE, and SH on MRI. Preoperative cephalograms showed that ACR (+) patients exhibited counterclockwise rotation of the mandible and retrognathism that was attributable to a small sella-nasion-B (SNB) angle, a wide mandibular plane angle, and a negative inclination of the ramus.
The present findings suggest that the development of ACR after orthognathic surgery to treat mandibular retrognathism may be associated with coexisting TMJ pathologic abnormality.