Which cephalometric analysis for maxillo-mandibular surgery in patients with obstructive sleep apnoea syndrome?

Maxillo-mandibular advancement MMA is considered an efficacious treatment for patients affected by severe obstructive sleep apnoea syndrome (OSAS). Even though OSAS improvement is the main goal of MMA, excessive maxillo-mandibular protrusion should be avoided to guarantee pleasant postoperative facial aesthetics. In order to attain such a result, the amount of MMA should be planned preoperatively by both aesthetic and cephalometric analyses. Steiner and Delaire cephalometric analyses are commonly used in the preoperative planning of orthognatic surgery for dentofacial deformities, however controversies still exist about the basis and postoperative aesthetic results of such cephalometric analyses in OSAS patients candidate for MMA. Forty-eight patients affected by severe OSAS were submitted to MMA. Pre- and post-operative Steiner and Delaire cephalometric tracings were assessed in each subject. For Steiner analysis, the variation in the SNA and SNB angles was measured, while for Delaire tracings the variation in the C3/FM-CPA and C3/FM-Me angles was assessed. Mean MMA was 6.9 + 3.8 mm for the maxilla and 13.6 + 5 mm for the mandible. After surgery, an improvement of the apnoea-hypopnoea index was recorded (40.47 + 7.64 preoperative vs. 12.56 + 5.78 postoperative). In all patients, both cephalometric analyses showed presurgical bimaxillary retrusion. After surgery, the mean value of Steiner's SNA angle increased from 78.18° to 85.58° (p < 0.001), while mean Delaire's C3/FM-CPA angle increased from 81.19° to 89.71° (p < 0.001). The mean value of Steiner's SNB angle increased from 74.33° to 80.73° (p < 0.001), while Delaire's C3/FM-Me angle increased from 80.10° to 87.29° (p < 0.001). Postoperatively, both the maxilla and mandible were in a more protrusive position (p < 0.001) according to Steiner analysis compared with Delaire tracing. Basing MMA on Delaire cephalometric analysis leads to an increased advancement of the maxillo-mandibular complex than Steiner tracing. The consequences of this aspect on facial aesthetics should be considered during surgical planning and preoperative informed consent in OSAS patients candidate for MMA.