[Dentofacial morphology of obstructive sleep apnea syndrome patients]

Sleep apnea syndrome is a condition characterized by recurrent interruption of breathing during sleep. Triad of symptoms for the disease are insomnia, daytime sleepiness and snoring. Recently, the patients complained of these symptoms have progressively increased. And so serious attention has been given to investigate the entity of this new clinical syndrome in medical and dental aspects. Three types of sleep apnea are classified; central, obstructive and mixed type. Most of patients identified this syndrome include obstructive or mixed types of sleep apnea. Obstructive sleep apnea has been presumed to have close relationships with obesity, micrognathia, retrognathia, tonsillary hypertrophy, tongue hypertrophy and so on. This study was designed to evaluate the characteristics of the dentofacial morphology in the obstructive, included mixed, sleep apnea syndrome (OSA) patients. The samples consisted of 25 adult male patients (average age of 48 years 2 months) with OSA as diagnosed by the division of respiratory disease, department of internal medicine, Kanazawa Medical University Hospital. One lateral radiographic cephalogram with the teeth in occlusion and the recording of somatic measurements, body weight and height, were obtained for each patient at visiting our orthodontic clinic. On the lateral cephalograms of whole samples, 10 angular and 6 linear measurements were carried out. Simultaneously, the body mass index (BMI) was assessed for each patient. Based on the cephalometric and somatometric measurements, the pathogenesis of obstructive sleep apnea was discussed in association with the obesity and dentofacial morphology. Results were summarized as follows: 1. The body mass index (kg/m2) ranged between 21.0 to 45.7, with a mean value of 31.0 for OSA patients. Of whom, 3 patients were mildly obese (25 or more of BMI) and 12 patients severely obese (exceeding 30 of BMI). 2. Compared with normal control samples, the means of cephalometric variables of whole samples showed the tendency of micrognathia, large gonial angle, protruded maxilla and large cranial base. 3. By principal component analysis, it was revealed that the components for the shape and position of the mandible were of more importance in OSA patients than controls. 4. Discriminatory analysis clarified significant differences in dentofacial morphology between 12 obese and 13 non-obese patients. 5. The dentofacial morphology in non-obese patients were characterized by retrognathia, micrognathia, large gonial angle and small maxilla. In accordance with previous reports, the patients with OSA were presented the tendency of obesity and micrognathia. Furthermore it was revealed that particularly in non-obese OSA patients the morphological abnormalities might be the major contributor to the pathogenesis of sleep apnea.