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There is no one mandibular advancement device design that fits all for the management of obstructive sleep apnea Ben Balevi JADA 2014;145(3):280-282 10.14219/jada.2013.36 The following resources related to this article are available online at (this information is current as of June 28, 2014): Updated information and services including high-resolution figures, can be found in the online version of this article at:

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There is no one mandibular advancement device design that fits all for the management of obstructive sleep apnea A critical summary of Ahrens A, McGrath C, Hägg U. A systematic review of the efficacy of oral appliance design in the management of obstructive sleep apnoea. Eur J Orthod 2011;33(3):318-324. Ben Balevi, BEng, DDS, Dip EBHC(Oxford), MSc

Clinical question. In adult patients with obstructive sleep apnea (OSA), how do mandibular advancement devices (MADs) of various designs compare with one another or with an inactive oral appliance with respect to measures of OSA severity? Review methods. Two independent reviewers screened the results of a literature search the authors conducted of four electronic databases. The authors included only randomized controlled trials (RCTs) limited to comparisons of MAD designs in their review. There was no language restriction. The primary outcomes were apnea-hypopnea index (AHI) and respiratory disturbance index (RDI) scores measured by means of polysomnography, although the methods of polysom-

nographic measurement used (in a laboratory setting or by means of portable monitoring devices) were not mentioned. The authors considered RDI or AHI scores greater than 10 to be diagnostic for sleep apnea. Main results. Fourteen RCTs (nine crossover and five parallel studies) that included 547 adult patients who had received a diagnosis of mild to severe OSA met the inclusion criteria. In six of the nine crossover RCTs, investigators reported washout periods ranging from one week to three months. Investigators in the other studies did not report a washout period. The dropout rate was 15 percent. Study durations ranged from two weeks to one year; nine studies lasted less than six weeks and one study lasted one year.

Owing to the heterogeneous definitions of treatment success across the studies, no meta-analysis was possible. MADs reduced participants’ polysomnographic index scores by 25 to 71 percent. The reported complete or partial success rates of MAD for OSA ranged from 25 to 100 percent. Conclusions. Regardless of the design, the use of MADs appears to improve patients’ polysomnographic index scores from baseline. The extent of their efficacy depends on a number of factors, including OSA severity, the materials and methods used to fabricate the device and the degree of mandibular protrusion. The source of funding for this systematic review was the General Research Fund, Hong Kong (project HGKU 772809M).

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COMMENTARY Importance and context. The prevalence of OSA in adults is approximately 3 percent.1 Untreated OSA is reported to be associated with many adverse health outcomes. Continuous positive airway pressure is the treatment of choice, especially in severe cases. For mild to moderate cases of OSA and in severe cases in which the patient cannot tolerate using a continuous positive airway pressure machine, an oral appliance fitted by a dentist such as a MAD is a recommended alternative.2,3 However, the dentist must select from many different MAD designs that may have varying degrees of effectiveness. Strengths and weaknesses of the systematic review. The authors asked a focused question when searching several databases without any language limitations. However, they may have missed some relevant articles by not hand searching specialized journals such as Sleep Medicine and Journal of Clinical Sleep Medicine. The authors included the appropriate study design (that is, RCT) with clearly defined outcomes (that is, polysomnographic index scores). They did not report their review’s search dates, but when I conducted an updated search on June 22, 2013, I did not find additional RCTs that met their inclusion criteria. The authors did not conduct an analysis of bias, a heterogeneity analysis or an assessment of publication bias, all of which may have threatened the validity of the review’s results and overestimated the favorable outcomes of MADs. The authors stated that a meta-analysis comparing the success among MAD designs or among all MADs and a control device was not feasible because of the variation in the definitions of treatment success. However, investigators in seven of the studies included a control group in which the device was nonactive for which a meta-analysis could have been conducted to compare the reduction in polysomnographic index scores between the test and control groups. Although such a meta-analysis would not necessarily have addressed the original clinical question, it at least would have given the clinician an idea of the extent of the clinical efficacy of MADs for managing OSA. Strengths and weaknesses of the evidence. The results of all 14 studies show that MADs are effective in reducing RDI scores (range, 43-66 percent) and AHI scores (range, 25-71 percent) for patients with OSA. The extent of the reduction was a function of the OSA’s severity at baseline. The results of one study showed that an MAD and an inactive control device were equally effective at reducing AHI scores by as much as 70 percent.4 However, the study had a small sample size and its investigators did not report the severity of the participants’ OSA. Washout periods

varied among or were not even described in some of the crossover studies included in the review. A washout period is necessary to avoid the influence of previous treatment on the outcome of the alternative treatment in the same patient. What constitutes a reasonable period to avoid contamination between treatments depends on how quickly the patient returns to baseline levels after stopping the first intervention (in this case, using the device).5 This threshold washout period was not discussed in any of the included studies, which could have contributed to selection bias. Furthermore, whether operators and outcomes assessors were masked was not clear in all of the studies. Lack of masking introduces the risk of overestimating the effect of the intervention, which could lead to operator bias. The cumulative dropout rate of 15 percent is relatively high, given that the study durations were generally short, with 13 studies lasting less than three months. This high attrition rate may be due to a lack of patient compliance or comfort with the device. If either is the case, MADs may not be as effective as the study results imply. Not accounting for dropouts can bias the result in favor of the desired outcome, leading to attrition bias. The definition of treatment success varied among studies and included reported improvement in symptoms by the patients, reduction of the polysomnographic index scores to an absolute threshold level (that is, AHI score of five per hour) and a 50 percent reduction of polysomnographic index scores from baseline. Because there was a lack of common success criteria, the authors argued that a metaanalysis comparing MAD designs was not feasible. Finally, no patient-oriented outcomes were reviewed. Doing so is important, as temporomandibular joint pain has been reported with patients’ use of MADs and the presence of pain would have affected their compliance and treatment prognosis.6 Implications for dental practice. There is evidence suggesting that MADs, regardless of design, may be generally effective at reducing patients’ polysomnographic index scores in cases of mild to moderate OSA. How this improvement translates to an improvement in the patient’s overall quality of health, including quality of life, is not clear. Therefore, the dentist’s choice of MAD design should be made on the basis of the patient’s acceptance of the device and on the results of a cost-benefit analysis. Once an MAD has been selected, the dentist should monitor the patient regularly to assess the MAD’s effectiveness and the patient’s compliance with using the MAD in terms of OSA status. n


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Dr. Balevi maintains a private practice in general dentistry in Vancouver, British Columbia, Canada, and is an associate with the faculty of medicine, University of British Columbia, Vancouver. He also is an evidence reviewer for the American Dental Association. Address correspondence to Dr. Balevi, 805 W. Broadway, No. 306, Vancouver, British Columbia, Canada V5Z 1K1, e-mail [email protected]. Disclosure. Dr. Balevi did not report any disclosures. These summaries, published under the auspices of the American Dental Association Center for Evidence-Based Dentistry, are prepared by practitioners trained in critical appraisal of published systematic reviews who work under the mentorship of experts. The summaries are not intended to, and do not, express, imply or summarize standards of care, but rather provide a concise reference for dentists to aid in understanding and applying evidence from the referenced systematic review in making clinically sound decisions as guided by their clinical judgment and by patient needs. For more information on the evidence quality rating provided above and additional critical summaries, please visit http://ebd.

1. Epstein LJ, Kristo D, Strollo PJ Jr, et al; Adult Obstructive Sleep Apnea Task Force of the American Academy of Sleep Medicine. Clinical guidelines for the evaluation, management and long-term care of obstructive sleep apnea in adults. J Clin Sleep Med 2009;5(3):263-276. 2. Lim J, Lasserson TJ, Fleetham J, Wright J. Oral appliances for obstructive sleep apnea. Cochrane Database Syst Rev2006;(1): CD004435. 3. Health Quality Ontario. Oral appliances for obstructive sleep apnea: an evidence-based analysis. Ont Health Technol Assess Ser 2009;9(5):1-51. 4. Blanco J, Zamarron C, Abeleira Pazos MT, Lamela C, Suarez Quintanilla D. Prospective evaluation of an oral appliance in the treatment of obstructive sleep apnea syndrome. Sleep Breath 2005;9(1):20-25. 5. Mills EJ, Chan AW, Wu P, Vail A, Guyatt GH, Altman DG. Design, analysis, and presentation of crossover trials (published online ahead of print April 30, 2009). Trials 2009;10:27. doi:10.1186/1745-621510-27. 6. Ahrens A, McGrath C, Hägg U. Subjective efficacy of oral appliance design features in the management of obstructive sleep apnea: a systematic review. Am J Orthod Dentofacial Orthop 2010;138(5): 559-576.

282  JADA 145(3)  March 2014 Copyright © 2014 American Dental Association. All Rights Reserved.

There is no one mandibular advancement device design that fits all for the management of obstructive sleep apnea.

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