The use of intraoral appliances in the treatment of obstructive upper airway (VAS) problems is not a new concept. As early as 1902, Pierre Robin advocated the use of an apparatus of these same characteristics (monobloc) to perform a functional overhang of mandibular, leading the latter to a more advanced position. This resulted in an additional tongue drag and avoided backward lingual glossoptosis that appeared during supine decubitus in children with mandibular hypoplasia1. The first publications of intraoral parasitology about SAHS emerge in the decade of the eighties of the last century2-5, as an attempt to seek alternative treatments, both surgical procedures and continuous positive pressure in the upper respiratory tract (CPAP).
Although more than 50 types of appliances have described in the market, 7.7 useful for the treatment of snoring, mandibular advancement devices (DAM) in both versions (fixed feed and adjustable feed) are the most effective in the management of snoring. Obstructive VAS problems.
Modify the position of the jaw
The American Sleep Disorders Association (ASDA) defines DAM8 as devices that are introduced into the mouth and modify the location of the mandible, tongue and other supporting structures of the VAS for the treatment of snoring and SAHS. It considered as a valid first choice alternative for simple snorers, mild SAHS patients, mild-moderate SAHS with low body mass index. Patients with increased resistance syndrome of the upper respiratory tract (SERVERS) and as a second choice in patients who do not respond or reject positive pressure devices, patients with high surgical risk and inadequate response to surgical treatment.
The AMD perform an anterior and inferior movement of the mandible generating anatomical variations in the VAS that manage to increase the pharyngeal sectional area. This action stabilizes and fixes the jaw and the hyoid bone, which prevents the postorrotación of these structures during the decubitus and avoids the occupation of the airway.
It has shown that in SAHS individuals the total percentage of time that patients sleep with an open mouth more than 5 mm (posterior rotation and retrusion), is significantly higher (69.3%) than in healthy individuals (11.1 %). Therefore, the movement of rotation and fixation of the jaw during sleep may be one of the essential elements during treatment with AMD. This concept may also explain why some patients get a good response with small advances even though no changes in VAS have observed during the studies of the pharyngeal light in wakefulness. Although its greater effect appears in the velopharyngeal zone, they have repercussions in all the pharyngeal segments. Initially, there seems an increase in stiffness and a widening of the space between the anterior and posterior pillars of the pharynx.
The clockwise rotation of the mandible and the massive increase in the vertical dimension activate the genioglossus muscle, which will be partly the cause of the changes occurring in the tongue16. Lowe et al17 have shown electromyographically how the tone of the lingual musculature (especially the genioglossus) increases after insertion of the AMD and how it descends again after removing the device. The tongue moves forward and occupies a superior position, making it difficult to fall backward during sleep18.
The mandibular functional advancement induces changes in the position of the hyoid bone to a more advanced position. A new equilibrium situation of the suprahyoid musculature appears that would favor the increase of volume and the permeability of the VAS23. This rise in VAS has documented by numerous authors with different scanning systems and imaging techniques.
Although the response is not the same in all patients, some authors admit that there is a dose-dependent effect. As the increase in the degree of mandibular advancement improves the clinical status of the patient.
Effectiveness of DAMs
Initially, case reports published, and an increasing number of cases appeared and, after several well-controlled clinical trials, we can say that, despite the considerable variability of designs found among AMD, there are sufficient endorsements in the scientific literature that demonstrate its effectiveness. All these published studies polysomnographically document the validity of the method.
Although initially, the design of the apparatus did not seem to be related to its effectiveness67, it has recently described that even the percentage of success can improved with the use of ADM with adjustable advance, which concludes that the more aggressive the results are protocols, the higher the success ratio. In the same order of things, some studies have appeared in which, as with CPAP (single-night titration), the titration of the ADM of adjustable advance during the night of the survey has tested. This would achieve the optimal therapeutic dose and would significantly shorten the advanced protocol. These trials, although promising, are trying to standardize given the high variability of tolerance and individual response to treatment.
There are also patients in whom good results not obtained: we refer to some severe SAHS. Since although there are evidence and positive data in this respect, the success rate is inferior about the mild and moderate, patients with protrusive deficiency mandibular advancement), massive overbite, cases with dental and periodontal problems and patients with temporomandibular joint (TMJ) pathology.
DAMs are very useful in the treatment of snoring (elimination in 50% of cases) and achieve a significant reduction of the same in 90% -100% of patients, as well as an improvement in sleep quality. Snoring also associated with an intermediate entity, such as SARVAS, in which drowsiness occurs along with an abnormal increase in esophageal pressure, but without measurable apneas/hypopneas. The remission or reduction of snoring in these cases suggests that AMD may be the treatment of choice.
In the polysomnographic registers, the benefits perceived by the patient are confirmed, with the reduction in the frequency and intensity of snoring, apneas, number of arousals and a significant increase of the sleep of slow waves and REM.
DAM vs. CPAP
CPAP can control most cases, while AMD does not have this efficacy. This fundamental advantage of CPAP partly offset by the better acceptance of AMD by patients. Even individuals with good response to both therapies tend to opt for AMD in a very significant percentage. Ferguson et al. compared efficacy, side effects, treatment follow-up, and individual preferences in a prospective randomized study. AHI was lower with CPAP (3.5 ± 1.6) than with AMD (9.7 ± 7.3). Other studies show similar figures for oxygen saturation, which is also higher with CPAP. But when analyzing personal satisfaction, follow-up and side effects, AMD’s were superior to CPAP. The preference of AMD over other therapies explained by different reasons, among which comfort, noise, electrical supply, claustrophobia, and irritation both cutaneous and VAS. It has reported that the use of AMD is less efficient than CPAP in patients with severe SAHS and should be limited to mild and moderate cases. Other studies, however, find no reason to exclude some of these patients and advocate their use even in severe cases, with excellent results but with significant individual variability.
Uvulopalatopharyngoplasty versus AMD
About some surgical procedures, such as uvulopalatopharyngoplasty, there are studies where AMD confirmed superior regarding individual preference and treatment efficacy. In addition, even in situations of surgical failure, AMD has been successfully used as a “rescue treatment” and has improved symptomatology in more than 50% of patients. Some intraoral appliances, such as palatal elevators (Palatal Lifting Devices), although they little used because of their poor results and poor patient tolerance, can be used as stent factors after a uvulopalatopharyngoplasty, since they make it difficult to retraction cicatrizant generated by it.
Qualified dental training
Management of AMD requires skilled dental practice, both for design and for adjustment and maintenance. The manufacture of the apparatus is only the first link in the treatment. DAMs must be accommodated according to protocols to achieve optimum results, both in efficiency and comfort for users. This process will take weeks or months and should evaluate along with sleep units. The European Dental Sleep Medicine Academy103 has made a detailed protocol for the use of these devices. This same body recommends that before placing an AMD in a SAHS patient. Two things should do the first: a diagnosis and a prescription of the device in the order sent to the dentist for specialized training; in this type of apparatus, by the doctors responsible for dental and medical history; soft tissue assessment, periodontal assessment, occlusal and temporomandibular examination. Evaluation of habits and parafunctions, testing, and the second, an adequate oral analysis by the professional in charge of the design and placement of DAM detail of the teeth and restorations present, as well as relevant x-rays and plaster models). It is the experienced clinician who selects and designs the most appropriate device for each particular case. Once the apparatus has been performed and adjusted, the patient trained for insertion and maintenance care. After getting the patient accustomed to the device, the progression gradually began (usually requiring weeks or months of adjustment) until a comfortable and adequate position is obtained to relieve snoring and sleep apnea. After this the patient must be re-evaluated in the unit of the dream. Before any adverse changes, a new visit to the sleep laboratory must be carried out, and the diagnosis must be re-performed. In these circumstances, a possible redesign or even change of apparatus may become mandatory. Patients receiving AMI require an average of regular visits during the first 12 months to ensure adequate well-being, retention, and outcomes for the disease.