Editorial 1, Issue 3.4

When Is a Monobloc Not a Monobloc? Cautions for Clinical Practice

Leslie C. Dort, DDS, Diplomate, ABDSM, Editor-in-Chief Journal of Dental Sleep Medicine
Calgary, Alberta, Canada

The authors of the recently published Journal of Clinical Sleep Medicine manuscript that compared mandibular advancement device (MAD) and nasal continuous positive airway pressure (CPAP) treatment outcomes1 are to be commended for their contribution to the area of MAD therapy. Their findings strengthen the evidence for positional obstructive sleep apnea (P-OSA) as a clinical predictor for MAD therapy outcome. The finding that MADs are as efficacious as CPAP in those with P-OSA supports the expanding use of MADs in the treatment of obstructive sleep apnea (OSA). This is not the first study to report equivalent outcomes when comparing MAD treatment to CPAP for those with OSA. Hoekema2 previously reported the findings of a randomized controlled trial demonstrating equivalence of treatment outcome in mild-to-moderate OSA patients without controlling for position. Hopefully, given that compliance with CPAP is poor and likely to be abandoned by patients, more patients will be given the opportunity to receive MAD therapy: an equivalent alternative.

There are concerns with some of the terms used in the manuscript and how they may be interpreted. The authors repeatedly term the appliance used a “monobloc” appliance as opposed to an “adjustable or titratable” appliance. The methods used in this study may mislead readers as to the results likely to be achieved with monobloc appliances. Monobloc appliances are single piece devices fabricated in a fixed, non-adjustable lower jaw position (protrusion). Clinicians expect to fabricate a monobloc MAD at one protrusive position and leave it there for the entire course of treatment until the device is worn out years later.

Titratable or adjustable MADs allow for increases (or decreases) in protrusive position at any time in the course of treatment by incorporating expansion screws or other mechanisms.

The present study by Takaesu et al.1 effectively turned a monobloc into an adjustable MAD. The MADs in the study were sequentially remade after being cut apart and repositioned at increased protrusive positions as required to achieve optimal outcome.

Many previous MAD studies, supposedly using “monoblocs,” have used similar methodology.3-5 These methods can lead to the false conclusion that monobloc MADs are equivalent to adjustable MADs in treating OSA. This conclusion in turn may lead to inadequate treatment of patients when clinics cannot duplicate the research procedures. Monoblocs in clinical practice are not cut apart sequentially and repositioned. This practice would be prohibitive in terms of clinician time and laboratory expense. It is only feasible under research conditions.

The cost of a clinical process using monobloc MADs repeatedly remade at increasing protrusive position is likely to be more than that employing an adjustable device. Thus the suggestion that a monobloc is a cost-effective alternative is misleading. The conclusion that an effective appliance is custom-made and titratable (adjustable) remains.6

While the authors have contributed to the field demonstrating equivalent outcomes achieved comparing MAD to CPAP treatment, the findings do not contradict the clinical guideline recommendation that “When oral appliance therapy is prescribed by a sleep physician for an adult patient with obstructive sleep apnea, we suggest that a qualified dentist use a custom, titratable appliance…” 7


Dort LC. When is a monobloc not a monobloc? Cautions for clinical practice. Journal of Dental Sleep Medicine 2016;3(4):109..


1. Takaesu Y, Tsuiki S, Kobayashi M, Komada Y, Nakayama H, Inoue Y. Mandibular advancement device as a comparable treatment to nasal continuous positive airway pressure for positional obstructive sleep apnea. J Clin Sleep Med 2016;12:1113–9.

2. Hoekema A, Voors AA, Wijkstra PJ, et al. Effects of oral appliances and CPAP on the left ventricle and natriuretic peptides. Int J Cardiol 2008;128:232–9.

3. Marklund M, Legrell PE. An orthodontic oral appliance. Angle Orthod 2010;80:1116–21.

4. Zhou J, Liu YH. A randomised titrated crossover study comparing two oral appliances in the treatment for mild to moderate obstructive sleep apnoea/hypopnoea syndrome. J Oral Rehabil 2012;39:914–22.

5. Walker-Engstrom ML, Ringqvist I, Vestling O, Wilhelmsson B, Tegelberg A. A prospective randomized study comparing two different degrees of mandibular advancement with a dental appliance in treatment of severe obstructive sleep apnea. Sleep Breath 2003;7:119–30.

6. Scherr SC, Dort LC, Almeida FR, et al. Definition of an effective oral appliance for the treatment of obstructive sleep apnea and snoring: a report of the American Academy of Dental Sleep Medicine. Journal of Dental Sleep Medicine 2014;1:39–50.

7. Ramar K, Dort LC, Katz SG, et al. Clinical practice guideline for the treatment of obstructive sleep apnea and snoring with oral appliance therapy: an update for 2015. Journal of Dental Sleep Medicine 2015;2:71–125.


Submitted for publication September, 2016
Accepted for publication September, 2016

Address correspondence to: Leslie C. Dort, DDS, 1016-68th Ave SW, Suite 150, Calgary, AB T2V 4J2, Canada; Tel: (403) 202-4905; Fax: (403)202-0266; Email:


Dr. Dort is Editor-in-Chief of Journal of Dental Sleep Medicine.