| LinkExchange Member | Free Home Pages at GeoCities |
| LinkExchange Member | Free Home Pages at GeoCities |
To return to main page, CLICK HERE
Differences in craniofacial structure have been observed in association with sleep apnea, such as retrognathia (receding chin). Orthodontists, experienced in jaw adjustments, have made devices to make the lower jaw protrude and hopefully relieve airway obstruction by the tongue as a result of pulling it forward. The concept is similar to that underlying surgical approaches such as genioglossus advancement and maxillomandibular osteotomy/advancement--but the orthodontic approach is obviously less drastic and more reversible.
The authors describe three types of appliances: tongue-retaining devices (which directly connect with the tongue to pull it forward); mandibular repositioners, which move the lower jaw forward and thus the tongue, which is connected to it; and equalizers, designed to life the soft palate or reposition the uvula and thus reduce the snoring sounds caused by its vibrations, which resembles somewhat in concept the common surgical uvulopalatopharnygoplasty (UPPP). Initial clinical experiences with such devices have been encouragin. The authors see a role for them in milder sleep apneics and simple snorers who cannot tolerate CPAP, but so far studies of these devices have not used adequate control groups, such as patients randomly assigned to one or another treatment, which this study was designed to accomplish in short-term evaluation of a mandibular repositioning device.
The authors studied 24 volunteers aged 25-69 with a history of loud snoring and a Respiratory Distress Index below 30 (excluding moderate to severe sleep apneics). Also excluded were those who had already had surgical treatment.
By random assignment, half the subjects initially received a SnoreGuard, designed to reposition the jaw forward 6-8 mm and also increase the vertical dimension of occlusion 8 mm, while the other half received a modified device only minimally increasing the vertical dimension (about 1 mm) and not advancing the jaw, as a control treatment expected to be inadequate.
Subjects completed the Epworth Sleepiness Scale (ESS) and received unattended in-home 6-channel sleep studies that measured oxygenation, airflow, snoring, body position, chest wall movement, and heart rate, but apparently not electroencephalogram (EEG) or electromyogram (EMG). Nevertheless, respiratory distress indices were calculated. Subjects received this evaluation prior to treatment and after two weeks of treatment. Also, subjects who initially received the second, inactive device later received the SnoreGuard and were reevaluated after two weeks with this.
In the first group, 10/12 subjects completed the two week trial and 9/10 showed improvement in RDI ranging from -4 to -57 (despite the entry criteria, 5 subjects had initial RDIs above 30, up to 78, and the average initial RDI was 36, with 8/12 at or above the common threshold of 20 for diagnosing sleep apnea). After 2 weeks, RDIs ranged from 6 to 70, averaging 21, significantly reduced from pretreatment, only 2 still above 20. ESS scores decreased significantly but more modestly, from an initial average of 12 to a final average of 8 (6 is sometimes considered the upper limit of normal).
With initial use of the second device, 4/12 subjects dropped out, and 6/8 actually increased their RDIs, the group as a whole averaging 36 at pretreatment and 47 at two weeks. Though this change was not statistically significant, the difference in outcome between the two devices was. Average ESS scores didn't change with the second device. When 7 subjects initially tried on the second device were switched to the SnoreGuard, 3 showed reduction in RDI and 5 in ESS, but on average these changes were modest (47 to 42 and 13 to 12 respectively).
The authors acknowledged several limitations to their study, but suggested the evidence for the advantage of the first device was enough to make the use of placebo devices unethical. They also suggested that mandibular positioning devices might be best used for people with craniofacial abnormalities demonstrable with cephalometrics.
When a treatment such as this dental device first enters the arena of controlled clinical research, we should restrain ourselves from overly criticizing the obvious defects in study design, aside from suggesting improvements for later studies. For example, the authors admit that their study groups were too small. They targetted snoring as a major criterion but entry but didn't use snoring as an outcome variable. Their failure to include EEG as a measure of actual sleep leaves the validity of their RDIs in doubt. It's unclear how many--if any--of the subjects actually had sleep apnea. The follow-up interval of two weeks is far too short, actually falling within the interval of possible placebo effects. When the person administering a placebo treatment knows that to be the case, he or she can often subtly communicate that to the patient, perhaps contributing to the high drop-outs and overall worsening seen in the second group.
Nevertheless, we should not be too quick to casually dismiss the orthodontic approach, because it does represent a reversible alternative to some irreversible surgical approaches. If the patient eventually opts for surgery, their history of favorable or unfavorable response to different types of dental appliances might help clue the surgeon in to the most useful surgical approach. Furthermore, dentists share with primary care providers like general practitioners and internists, the role of "first line of defense" in detecting sleep apnea and directing patients towards treatment. There are few sleep specialists and few patients who see them without first having fairly clear indications of a sleep disorder, but almost everyone sees a GP or a dentist at some time, and these clinicians are in a position to detect possible sleep apnea even when the patient fails to recognize the presence of a sleep disorder. Thus, the role of dentists in this illness is potentially important and it is important that they become interested in and knowledgeable about its symptoms, diagnosis, and treatment.
WHAT DO YOU THINK ABOUT THIS ARTICLE AND MY COMMENTS?
CAN YOU RELATE THIS MATERIAL TO ANY PERSONAL EXPERIENCES?
Get your own Free Home Page