Treatment of obstructive sleep apnea with the Karwetzky oral appliance.

The aims of this retrospective study were to assess the effect of a Karwetzky mandibular protrusion appliance for treating patients with mild, moderate, and severe obstructive sleep apnea. Eighty-one of 116 patients (69.8%) suffering from obstructive sleep apnea were treated with an activator model according to Karwetzky. After 4 months (SD 4.0 months) treatment outcome was controlled by polysomnography. Therapeutic outcome depended on the severity of obstructive sleep apnea. The median apnea-hypopnea index decreased from 10.6 events/h (range 2.0-14.9) to 5.8 events/h (range 0.2-17.3, P<0.01) in the mild group, from 21.7 events/h (range 17.3-28.4) to 7.7 events/h (range 1.0-30.1, P<0.001) in the moderate group, and from 42.1 events/h (range 33.2-64.9) to 18.1 events/h (range 2.4-48.8, P<0.001) in the severe group. Sleep variables did not show consistent improvement except for a trend towards more REM sleep and slow-wave sleep. The numbers of retentive teeth did not statistically influence treatment efficacy. Comparing the pre- and post-treatment polysomnographic variables, it was found that the respiratory events rather than sleep stages were significantly reduced by the Karwetzky appliance investigated.