Effects of a mandibular repositioner on obstructive sleep apnea

The teaching and treatment of upper airway sleep disorders in North American dental schools

STATEMENT OF PROBLEM

Many dental patients suffer from upper airway sleep disorders (UASD) that affect the quantity and quality of their sleep. These disorders vary from minor annoyances to life-threatening conditions. Even though dentists can play a role in the successful treatment of these patients with oral devices, few do. This lack of participation, in part, may be due to lack of education.

PURPOSE

The purpose of this study was to determine which North American dental schools include the treatment of UASD in their curriculum. This information may prove helpful to other schools in determining whether, and to what degree, they should teach about UASD and its treatment options.

MATERIAL AND METHODS

A survey instrument (questionnaire) was mailed to all of the North American dental schools (n = 64) affiliated with the American Association of Dental Schools. The questionnaire consisted of 9 multipart questions. Major categories of questions included the following: (1) Is the subject of UASD a part of the school curriculum? If so, in what department is it taught? (2) Are oral devices fabricated for patients or is the experience only at the didactic level? (3) What diagnostic procedures are required? (4) What types of oral devices are fabricated and what is the success rate/recall frequency? (5) What is the patient source? (6) If this subject area is not covered either didactically or clinically, why not? The data were analyzed by use of descriptive statistics.

RESULTS

Forty-three of the 64 schools that received the survey responded. Forty-two percent of the schools that responded are teaching the treatment of UASD with oral devices. There is no apparent consensus with regard to whether to teach the subject, at what level, or to what degree.

CONCLUSION

Even though many dental patients suffer from potentially life-threatening sleep disorders, many of which could be treated with oral devices, fewer than half of the reporting dental schools currently include this area as part of their curriculum. This lack of inclusion is caused primarily by a lack of familiarity with the information available and a lack of available curriculum time.

The efficacy of a mandibular advancement splint in relation to cephalometric variables

The efficacy of a titratable mandibular advancement splint (MAS) for the management of obstructive sleep apnea (OSA) was investigated in relation to supine cephalometric variables. Fourteen adults with diagnosed OSA were recruited following an initial polysomnogram. Supine cephalographic radiographs were taken at baseline and subjects wore the MAS nightly for 6 to 8 weeks. The polysomnogram and cephalogram were repeated with the MAS at maximal titration. The MAS resulted in complete or partial treatment response in all subjects as measured by the improvement in mean apnea/hypopnea index (AHI) (baseline AHI 34 +/- 22/hr, with MAS 10 +/- 5/hr; p = 0.001). The perpendicular distance between the hyoid bone and the mandibular plane (HYML) measured in awake subjects decreased with the MAS (baseline HYML 25.3 +/- 7.8 mm, with MAS 16.5 +/- 9.6 mm; p = 0.002). Baseline HYML was the only cephalometric variable associated with a successful clinical outcome. It was strongly linked to improvements in AHI (adjusted R(2) = 0.37, p = 0.012) and arousals (adjusted R(2) = 0.455, p = 0.005). We conclude that the MAS is an effective therapy for OSA and baseline HYML is an important predictor of improvement. Improvements in AHI may be explained by the MAS maintaining the new or existing relationship of the hyoid and its surrounding structures, thus preventing obstruction in the upper airway during sleep.

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.

Therapeutic efficacy of an oral appliance in the treatment of obstructive sleep apnea: a 2-year follow-up

The purpose of this study was to investigate the long-term efficacy of an oral appliance, the Karwetzky activator, on respiratory and sleep parameters in patients with obstructive sleep apnea (OSA). Those selected for this study were 26 patients polysomnographically diagnosed with mild-to-moderate OSA. They were initially treated successfully with this appliance, as documented by a second polysomnographic study after 6 to 12 weeks. Further polysomnographic registrations 6 to 12 months and 18 to 24 months later were performed for each patient wearing the appliance. For 21 patients (81%), therapeutic efficacy was maintained; 5 patients (19%) showed a deterioration in respiratory parameters. We corrected this by adjusting the device in 2 patients. The mean apnea-hypopnea index decreased significantly from 17.8 events per hour at the baseline registration to 4.2 events per hour (P <.001) after 6 to 12 weeks of treatment. After 6 to 12 months, the apnea-hypopnea index was 8.2 events per hour. The index remained at this level 18 to 24 months later, with 8.3 events per hour. Mean oxygen saturation was not improved with the activator, but the number of desaturations had decreased at the 6-to-12 week review. Again, the improvement declined with time, but the number of oxygen desaturations was still significantly decreased at 18 to 24 months (P <.01). Although the respiratory parameters remained statistically improved throughout the study (P <.01), sleep architecture did not change statistically. In most patients, therapeutic efficacy was maintained at the 2-year follow-up, although there was a tendency for effectiveness to fall over time. We concluded that the Karwetzky activator may be an effective treatment alternative for patients with mild-to-moderate OSA, but therapy requires diligent and regular polysomnographic follow-ups. Further long-term studies are needed to assess the continued efficacy of this oral appliance in treating OSA.

Is adjustability advantageous in mandibular advancement appliances in the treatment of sleep-disordered breathing?

Mandibular advancement appliances (MAD) that can adjust the amount of mandibular protrusion in response to treatment results are becoming popular with dentists who treat sleep-disorder breathing. Clinicians commonly assume that they are more efficacious and more comfortable to wear than monoblock appliances. An adjustable MAD was compared with one that stabilized the mandible at 70% of the protrusive path. There was not a significant difference in their overall efficacy. The adjustable MAD appeared to be more effective in the more severe cases, presumably due to the greater mandibular advancement; the nonadjustable MAD appeared to be more effective in the less severe cases, presumably due to the greater mandibular stabilization. Existing research was examined and biomechanical principles were considered. Insufficient research exists to definitely evaluate the pros and cons of adjustability vs. stability. There does not appear to be sufficient evidence to support the assumption that adjustable MADs are more efficacious or more comfortable to wear than monoblock appliances.