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Mandibular Advancement Splints, Obstructive Sleep Apnoea and Occlusal Derangement: A Case Report Brian M Quinn Giles McCracken Dental Update 2025 51:11, 793-795.
Authors
Brian MQuinn
BDS, MFDS RCPS(Glasg), Specialty Registrar in Restorative Dentistry, Dundee Dental Hospital and Research School
Obstructive sleep apnoea is a sleep-related respiratory condition. It can present to dentists through obtaining a patient's medical history. If left untreated, it is associated with several serious morbidities. Mandibular advancement splints can be used as a treatment modality; however, if fabricated incorrectly, detrimental occlusal effects can occur.
CPD/Clinical Relevance:
Awareness of occlusal changes that can occur with the use of partial coverage designs of mandibular advancement splints is of value.
Article
Obstructive sleep apnoea (OSA) is a common sleep disorder affecting an estimated 1.5 million adults in the UK. The British Lung Foundation describes it as a sleep-related respiratory condition. During sleep, it results in repeated temporary breathing cessations owing to the narrowing or closure of the upper airway.1
If left untreated, OSA is associated with serious morbidities, including metabolic disorders (for example, diabetes), cardiovascular disease (for example, hypertension or stroke), cognitive impairment and depression. It is also associated with decreased productivity and motor vehicle accidents, resulting in injury and fatality.2 Symptoms of OSA include hypopnea (described as a period of shallow breathing) or apnoea (the complete cessation of breathing).3 Patients commonly present with a history of nocturia, morning headaches, excessive daytime sleepiness and fatigue, increased irritability and memory loss.2 Often, OSA is diagnosed and treated in specialist sleep clinics, usually after a patient presents to their general medical practitioner (GMP) with any of the above symptoms. Once referred, they may undergo an assessment of breathing and heart rate while they are asleep. These investigations aid in the diagnosis of sleep apnoea and can also highlight its severity.4
OSA can have several causes, one being reductions in pharyngeal lumen size. This reduction is thought to increase the collapsibility of the airway, resulting in airway partial occlusion or full occlusion as seen in OSA.5
Obesity is thought to be the largest causative factor reported in patients with OSA, with the prevalence increasing from 70% to 95% with increasing body mass index from 40 kg/m2 to 60 kg/m2. Differences in craniofacial structure have also been suggested as causes of OSA in young, healthy-weighted people.5
Four physiological traits have been reported to cause OSA, which include Pcrit (air pressure at which the passive airway collapses), loop gain (stability of ventilatory chemoreflex feedback control), arousal threshold (negative intra-oesophageal pressure that triggers arousal) and upper airway recruitment threshold (level of stimuli required to activate upper airway dilator muscles).5
There are currently several treatment options available for patients with OSA. These include positive airway pressure, surgery, mandibular advancement splint (MAS), positional therapy, weight loss and hypoglossal nerve stimulation.5 Smoking cessation and reducing alcohol intake may help, as they are also cited to be causative factors.4
The treatment options outlined above have limitations. Regarding the use of a MAS, the side effects that are most reported are jaw discomfort, tooth tenderness, hypersalivation and xerostomia. These side effects are usually temporary or transient and are more likely to occur during the early stages of treatment with an oral appliance.6
MASs can also have dental and skeletal effects. There may be an increase in lower incisor proclination, decrease overjet, decrease overbite, rotation of the mandible downward and forward, and an increase in the SNA angle. Even though the current level of evidence is weak, and the actual values are not thought to be clinically significant, caution should still be exercised when providing oral appliances for the treatment of OSA.7
Background
In May 2022, a 62-year-old female patient presented at a general dental practice, concerned with her unusual ‘bite’ and ‘jaw problems’. The patient had received orthodontic treatment with aligners approximately 5-years previously, completed at a different practice. Following completion and onward referral, she was diagnosed with OSA and provided with a MAS for its management. Over the following years, the patient noticed a gradual change in the ‘overlapping’ of her anterior teeth. The description given suggested a progressive anterior open bite (AOB), which was also associated with increased difficulty during eating.
Presenting problem
The patient provided a detailed history and reported embarrassment when eating in public, especially sandwiches, and an inability to bite ‘sellotape’. Regarding her jaw, she recalled an episode approximately 2 years prior to presenting to the unit, where she yawned and heard a loud ‘crack’. From this point, she felt the situation with her occlusion changed dramatically.
Besides the patient's diagnosis of OSA, the patient was medically fit and well, with the only other diagnosis of note being anxiety managed by her GMP. At the time of presentation, her medications included citalopram and pantoprazole. The patient had a history of cigarette smoking, having quit 15 years previously and she consumed approximately 8 units of alcohol per week.
Previous clinical management
The patient's previous diagnosis of OSA was through the local NHS sleep medicine services. It was not deemed severe enough to have continuous positive airway pressure (CPAP) therapy prescribed. Hence, the reason for her sourcing a MAS privately from a local dental practitioner. The patient used this oral appliance with great success in reducing the effects of OSA.
Examination
On examination, extra-orally there was nothing of note regarding the patient's temporomandibular joints (TMJ). No clicks or pain was detected on palpation. There were no findings of note with the muscles of mastication, lymph nodes or salivary glands on palpation. The pathway of opening of the TMJ gave a right-hand side deviation of the mandible, with limited lateral excursive movements to the right-hand side.
Intra-orally, there was a significant AOB (Figure 1), with occlusal contact isolated to the right side maxillary and mandibular third permanent molars only (Figure 2). All other teeth were out of occlusal contact in both ICP and excursions (Figure 3).
Figure 1. The anterior open bite.Figure 2. The occlusion isolated to the right maxillary and mandibular third permanent molars.Figure 3. The disocclusion on the left-hand side is shown (a,b) in the natural dentition and (c) in the study model.
Examination of the MAS that was in use revealed no occlusal coverage to maxillary and mandibular third permanent molars on the right-hand side (Figure 4).
Figure 4.
(a) The mandibular advancement splint shows the lack of occlusal coverage over the lower right third molar; (b,c) lateral views; and (d) lack of occlusal coverage over the upper right third molar.
Clinical diagnosis
It was thought that owing to the absence of full occlusal coverage with the MAS, the maxillary and mandibular right third permanent molars had moved and/or overerupted, thus leading to a significant derangement of the occlusion and revised intercuspal position as shown in Figures 1–3.
The history and clinical examination suggested that there had probably been a repositioning of the right condyle, and possibly the left condyle, within the glenoid fossa(e), leading to the mandible pivoting around the change in the single occlusal contact on the right side. This movement is possibly similar to how the ‘last tooth in the arc’ syndrome occurs and potentially complicated through a reposition or displacement of the articular disc within the right TMJ.8
Further investigation through MRI or CT imaging would have been helpful to further confirm any intra-joint derangement, but was not likely to change the management of the case and, therefore, was not undertaken as a first line of conservative treatment.
Initial management involved the dental team engaging with sleep medicine and arranging for the patient to be transferred to CPAP for their OSA management, removing the necessity to use a MAS. Since halting split use, the patient has continued to function without orofacial pain or discomfort. There is slow but progressive resolution of the occlusal derangement and the patient is under regular review.
Discussion
This finding is not unprecedented, and while the literature is not in agreement, case reports and research studies of different designs regarding partial and full coverage occlusal appliances have reported a significant decrease in the number of occlusal contacts in the molar and premolar region.9 This lack of posterior contacts is observed in MASs, and more surprisingly, in CPAP patients.
In patients with more severe OSA, CPAP is the preferred alternative to a MAS.10 Both come with occlusal side effects; however, surprisingly, a lack of posterior contacts is also observed in CPAP patients. The decrease in overbite and overjet when using an oral appliance may explain this phenomenon in MAS groups. However, it does not explain why this phenomenon also occurs in patients using CPAP to treat their OSA. Therapy with CPAP does not inflect mandibular protrusion, and it has, therefore, been suggested that the use of a tight-fitting nasal mask may result in retroclination of the maxillary incisors. The proposed mechanism is through the exertion of increased pressure on the anterior maxilla and subsequent autorotation of the mandible, with resulting reduction in the number of occlusal contacts.11
Conclusion
The authors feel that it is important to raise this potential hazard in the management of OSA with MASs with the profession, prior to completing the management of this case to resolution of the derangement of the occlusion. The dentist's role in treating OSA is widespread in the UK and beyond, with patients seeking help directly rather than engaging with sleep medicine. In many instances, providers of occlusal appliances have become highly visible through the internet and promoted on social media as the first point of contact. Dentists are familiar with providing therapeutic nocturnal splints, for example, in patients with temporomandibular disorders and tooth surface loss to manage bruxism and/or other parafunctional habits. However, caution is advised when considering the provision of an oral appliance as part of the management plan, as unexpected dental-related consequences and occlusal disharmony can arise.
Patients provided with a MAS are likely to be unaware of the potential subtle changes to their occlusion over time and may only become aware and present back to dentists after changes are significant. As with the case outlined above, once these occlusal derangements occur, they can be difficult, protracted, and unpredictable to manage. As such, it is important that these patients have regular follow-ups with dental services, even when symptoms of their OSA have improved.
