The topic of sleep-related breathing disorders (SRBD) has received significant attention in dentistry over the past decade with bourgeoning literature in multiple disciplines such as pediatric dentistry, prosthodontics, orofacial pain, and of course orthodontics and dentofacial orthopedics. What do you as a practitioner need to know about the current state of orthodontic research in this ever-important field?
Sleep-related breathing disorders (SRBD) is one of eight subcategories of sleep disorders that were published in 1990 as the International Classification of Sleep Disorders (ICSD). Snoring, obstructive sleep apnea (OSA), and upper airway resistance syndrome are only few examples of SRBD conditions. The consequences of SRBD on the affected individual, the society, and the health care system are immense. Examples of general health morbidities include heart disease and dementia, while oral health morbidities include dry mouth and periodontal disease.
The diagnosis of SRBD can only be made by a physician with the use of objective sleep tests such as overnight polysomnographic sleep studies, multiple sleep latency tests, in addition to other diagnostic modalities. Overnight sleep studies are now being conducted for little over 40 years, which is not a long time. The presence and severity of SRBD can be described using several indices, the most common of which is the Apnea-Hypopnea Index (AHI), developed by Dr. Christian Guilleminault in 1976. An AHI from 1 to 5 episodes per hour indicates OSA in children, where the prevalence of this condition in both genders is around 10%. The consequences of SRBD on the pediatric population include impaired school performance and behavioral problems such as Attention-Deficit/Hyperactivity Disorder (ADHD).
Although orthodontists cannot diagnose SRBD, they are encouraged to screen and refer to medical care as needed. There are multiple tools that are available for orthodontist to screen for pediatric SRBDs. One example is the BEARS questionnaire, which asks about bedtime, excessive daytime sleepiness, awakening during the night, and snoring.
Snoring is a hypopnea causing only partial airway obstruction. In adults, only habitual snoring (with frequency over 4 times per week) is related to SRBD. However, in the pediatric population, snoring of any frequency is problematic and requires further attention.
Multiple factors contribute to the etiology of Pediatric SRBD. The most common etiologies are adeno-tonsillar hypertrophy and craniofacial abnormalities, including mandibular retrognathism, maxillary constriction, and dolichocephalic growth pattern. Earlier observations related to these etiologies were made by Edward H Angle in 1907, who noticed that Class II children had narrower upper airways than children with normal skeletal patterns.
The first line of management is adenotonsillectomy surgery, which has been found to have success rates as high as 75%. The next is nasal positive airway pressure. Both interventions have been shown to improve the child’s behavior and quality of life. However, with predisposing factors such as obesity and family history of OSA, some children continue to have residual OSA.
Orthodontists have been involved in treating craniofacial abnormalities in children and adolescents for over a century. There is abundant evidence on the short- and long-term dentoskeletal and soft tissue effects of the different orthodontic interventions on the craniofacial structures. Nonetheless, more recently, new evidence now suggests that orthodontic interventions may improve or protect against pediatric SRBD.
With the burgeoning research in this area, the question still remains to be answered, do orthodontic interventions using devices such as rapid maxillary expansion (RME), Class II functional correctors by mandibular advancement, and maxillary protraction devices have anything to do with SRBD? Most of the studies addressing this topic were conducted on healthy children/adolescents by assessing pre- and post- airway dimensions and hyoid bone position as well as other variables. Few studies focused on children with an established diagnosis of SRBD.
Can treatment with RPE improve pediatric SRBD? In SRBD-affected subjects, there is some evidence that RPE reduces nasal airway obstruction. There is also low-quality evidence of a short-term (less than 3years post-RPE) improvement in AHI and lowered oxygen saturation rate but no clear evidence for a long-term effect. Also, evidence related to the changes in the upper airway dimensions in healthy subjects is conflicting.
What about functional appliances for Class II correction? Limited evidence suggests that mandibular advancement devices may improve the AHI in children with OSA, but no evidence exists to support them as a cure for OSA. More recent evidence comes from a systematic review that we conducted at the University at Buffalo in which we evaluated the effects of mandibular functional appliances on the upper airway dimensions in non-OSA children and adolescents. Using evidence from CBCT studies only, we found limited increase in the upper airway dimensions and volume in the short-term (end of orthodontic treatment) but no evidence was found for a long-term effect.
What about maxillary protraction appliance for Class III correction? evidence on these appliances indicates an increase in the superior component of the upper airway and is mostly focused on children with craniofacial abnormalities/syndromes.
An increasing number of orthodontic practices are now advertising that orthodontic braces and RPEs can improve or even “cure” SRBD. With the limitations in the orthodontic literature, we need to be cautious in terms of our marketing to the public related to what our interventions can and cannot do. Some of these limitations, as well challenges, are highlighted below.
There is significant variability in the definitions of habitual snoring (is it 5-7 days per week? 2-4 days? Or other?). Most studies assessed the airway in its static state using 3D cone beam CT or 2D lateral cephalograms. As we all know, airway is a dynamic structure and thus dynamic examinations such as drug-induced sleep endoscopy (DISE), dynamic 3D or sleep cine magnetic resonance imaging (MRI) need to be considered. There is significant variability among studies with regards to the cone beam CT image settings, such as exposure times and projection geometry.
Most orthodontic studies used images taken with the subjects seated in an upright position which does not mimic the airway during sleep. There are differences in the airway between the sleep state supine position, where there is less muscle tone, and the upright awake position with teeth in maximum intercuspation.
Most studies were limited by small sample sizes, absence of control groups, and high risks of bias (low methodological quality). There is lack of evidence on the long-term effects of the different orthodontic interventions. Additionally, improvement in the airway dimensions does not necessarily imply an improvement in SRBD.
With the limitations in evidence comes the challenges in practice. Are we preparing our students to manage SRBD? Despite the significant negative impact of sleep disorders on the society, there are limitations in the training of pre-doctoral dental students on sleep disorders. Simmons and Pullinger in their 2012 cross-sectional survey reported that around 76% of dental schools in the country teach about sleep disorders. The mean class hours were 3.92 and the range was from 0-15hrs with most of the teaching being didactic and only few schools incorporated clinical exposure in the form of clinical management or observation. The topics that the dental schools covered were mostly on SRBD (in 32 schools) and sleep bruxism (in 31 schools).
The question remains, however, is 3.92 hrs enough to achieve competency in this area? Are graduates able to screen, refer, and perhaps co-treat individuals affected by sleep disorders? When we look at the advanced education orthodontic programs, there is also significant variability with regards to teaching sleep disorders. How much are we teaching our advanced education orthodontic residents and the adequacy of that teaching are questions that need further elucidation. The orthodontics and dentofacial orthopedics Commission on Dental Accreditation (CODA) standards do not encompass competencies related to sleep disorders, but luckily the profession has started to take formal steps towards adding the management of patients with sleep related breathing disorders as competency into the CODA standards. Other disciplines such as prosthodontics and orofacial pain already have in their standards requirements of formal instruction in sleep disorders and sleep medicine.
In conclusion, sleep disorders are multidisciplinary in nature and all disciplines in dentistry and in medicine need to come together to organize the practice of managing patients with sleep disorders. An educational model is also needed to provide adequate training and prepare our students for practice.
It is essential that we advance our scientific methods to clarify the effects of our orthodontic interventions on sleep disorders including SRBD, then market accordingly.
Given the epidemic nature of sleep disorders (affecting over 28 million in the United Stated), the needs to manage this condition far exceed the supply of health care providers. The onus is on us to organize our efforts to address SRBD among children.
- Camacho, Macario et al. “Rapid maxillary expansion for pediatric obstructive sleep apnea: A systematic review and meta-analysis.” The Laryngoscope127 7 (2017): 1712-1719.
- Simmons, M. & Pullinger, A. Sleep Breath (2012) 16: 383. https://doi.org/10.1007/s11325-011-0507-z
Thikriat Al-Jewair, Assistant Professor, University at Buffalo Director, Advanced Education Program in Orthodontics