Cephalometric predictors for orthopaedic mandibular advancement in obstructive sleep apnoea.

The cephalometric analysis of two groups: 30 sleep apnoea patients, and 30 age- and sex-matched control patients, established predictors for the orthopaedic mandibular advancement by means of the Esmarch device (ED) in treating obstructive sleep apnoea (OSA). Polysomnographic sleep and ventilation data gathered for each patient with and without mandibular advancement by means of the ED were compared. Cephalometric data and treatment efficacy for each patient were submitted to a regression analysis. Maximal efficacy is predicted by: 1. The combination of an orthognathic to prognathic maxilla (SNA larger than or equal to 83 degrees) with an orthognatic to retrognathic mandible (SNB less than or equal to 77 degrees) 2. An anterior superior displacement of the mandible, with the supramentale situated at a distance from the anterior part of second cervical vertebra (B-HWK 2 longer than or equal to 95.5 mm) and a narrow angle between the skull and the mandibular ramus (SN/B-Go equal to or less than 1.5 degrees) 3. Short oral height (TB-PNS equal to or less than 35.5 mm), with the uvula not extending beyond the tongue base (UT-PNS, equal to or less than 30 mm). 4. A narrow oropharynx (PAS equal to or less than 3.4 mm). The narrower the SNB-angle, the wider the SNA-angle, and the shorter the uvula, the more effective the device.