Principles of oral appliance therapy for the management of sleep disordered breathing

Abstract

Dentists have recently become one of the team players in the field of sleep medicine. Oral appliances for the treatment of snoring and obstructive sleep apnea (OSA) fall into two main categories: those that hold the tongue forward and those that reposition the mandible (and the attached tongue) forward during sleep. Before treating either snoring or OSAwith any oral appliance, a complete assessment by a knowledgeable physician or sleep disorder specialist is important. Having concluded that treatment with an oral appliance is indicated, the physician provides the dentist/orthodontist/oral surgeon who has skill and experience in oral appliance therapy with a written referral or prescription and a copy of the diagnostic report. Because of the obvious life threatening implications of a number of sleep disorders, it is imperative that oral appliance therapy commences only after a complete medical assessment. The American Academy of Sleep Medicine reviewed the available literature in 1995 and recommended that oral appliances be used in patients with primary snoring or mild OSA and in patients with moderate to severe OSA who are intolerant of or refuse treatment with nasal continuous positive airway pressure (nCPAP) [1,2]. For some patients, combination therapy with other treatments such as weight loss, surgery and nCPAP may be indicated, and this must be coordinated by the attending sleep physician. Current evidence suggests that the pathogenesis of OSA involves a combination of reduced upper airway size and altered upper airway muscle activity. Features and size of the upper airway have been characterized by cephalometry [3], CT [4,5], and MRI [6]. A high apnea index (AI) was seen in association with a large tongue and soft palate volume, a retrognathic mandible, an anteroposterior discrepancy between the maxilla and mandible and an open bite tendency between the incisors, and obesity [6]. Cephalograms may be useful to estimate the volume of the tongue, nasopharynx, and soft palate but not the oropharynx or hypopharynx [7]. Tongue posture appears to have a substantial effect on upper airway morphology [8]. Tongue cross-sectional area increases and oropharyngeal cross-sectional area decreases when OSA patients change their body position from upright to supine [6]. Oral appliances are believed to have a direct effect on mandibular posture and consequently affect airway size. Three-dimensional analyses have increased our understanding of the mechanisms of different forms of treatment including oral appliances [9,10] and nCPAP [6] and have helped predict the response to upper airway surgery [11]. Tongue and soft palate