Long-Term Care and Side Effects of Mandibular Advancement Splints: What Every Patient Should Know product guide

Long-Term Care and Side Effects of Mandibular Advancement Splints: What Every Patient Should Know

Mandibular advancement splints (MAS) are one of the most effective non-invasive treatments available for obstructive sleep apnoea (OSA), snoring, and bruxism. But because OSA is a chronic condition requiring lifelong management, MAS therapy is not a short-term intervention - it is a commitment that can span a decade or more. That clinical reality makes the long-term side effect profile of MAS therapy one of the most important, and most frequently under-discussed, aspects of oral appliance care.

Most competitor content describes MAS devices in terms of their benefits and fitting process. Far less is written about what happens to the jaw, the bite, and the device itself after years of nightly use. This article fills that gap directly. Whether you have just been fitted for your first splint or have been wearing one for several years, understanding the progressive nature of MAS side effects - and the monitoring and mitigation strategies that protect against them - is essential for safe, sustainable treatment.

(For a foundational explanation of how MAS devices work and who they are appropriate for, see our guide on [Mandibular Advancement Splints Explained: How They Work, Who They're For, and What to Expect].)

The Two Categories of MAS Side Effects: Transient vs. Progressive

Clinicians categorise MAS side effects into two distinct groups that differ fundamentally in their time course, mechanism, and clinical significance.

Short-term side effects include mouth dryness or hypersalivation, tooth discomfort or oral mucosa swelling, occlusal discomfort when waking up, or temporomandibular joint pain. These are common in the acclimatisation phase and, for most patients, resolve with time and device adjustment.

Long-term side effects include excessive lingual inclination of the mandibular teeth, labial inclination of maxillary teeth, and overjet and overbite reduction.

Understanding which category a symptom falls into determines the appropriate clinical response - from watchful waiting to device modification to escalated monitoring. The following sections address each in detail.

Transient Side Effects: What to Expect in the First Weeks and Months

Jaw Soreness and Muscle Tenderness

Jaw soreness is the most universally reported early side effect of MAS therapy. The most commonly reported side effects were jaw discomfort, tooth tenderness, excessive salivation, and dry mouth. These symptoms arise because the device holds the mandible in a protruded, vertically open position throughout the night, placing sustained mechanical load on the masticatory muscles, the temporomandibular joint (TMJ), and the periodontal ligaments.

MAS are anchored to dentition and hold the mandible in a forward, vertically open position, pulling forward the tongue base and stretching pharyngeal soft tissues; these devices hold the mandible in an advanced and vertically opened position, generating a continuously applied load to teeth and surrounding tissues by means of the traction forces exerted by the masticatory and mylohyoid muscles and soft tissue.

For most patients, muscle tenderness resolves within the first few weeks as the neuromuscular system adapts. Jaw soreness, tenderness in the temporomandibular joint (TMJ), and soreness in the chewing muscles are among the most frequently reported issues. These symptoms often resolve within days to weeks, especially with proper adjustment and monitoring from a qualified sleep dentist.

Excess Salivation and Dry Mouth

Hypersalivation and dry mouth appear paradoxical but both are common early complaints. Hypersalivation, dry mouth, and tooth discomfort were the most common subjective side effects of OA therapy. Excess salivation occurs because the oral appliance stimulates salivary gland reflexes; dry mouth typically affects mouth breathers whose lips part during sleep, allowing airflow to desiccate the oral mucosa. Both effects tend to diminish significantly within the first month of use.

Morning Bite Changes (Transient Malocclusion)

A particularly common and initially alarming complaint is waking with a bite that feels "off" - the upper and lower teeth do not meet as they normally would. An often-mentioned side effect of mandibular advancement is morning malocclusion. Some patients report, "My bite doesn't fit in the morning." It has been shown in an objective study that a greater amount of protrusion can lead to more side effects.

The mechanism involves the TMJ itself. By stabilising the lower jaw forward in one position for an extended period of time, the upper synovial compartment is not compressed flat by the condylar head of the joint. This allows for the potential space inside the upper compartment to balloon up with synovial fluids caused by blood pressure. Once the oral appliance is removed after a prolonged period of use, the joint cannot fall back into its usual place because of this ballooned upper compartment space. Therefore, the teeth cannot position themselves into the right bite as long as the joint is not in its proper place.

In most cases, this morning malocclusion is transient and self-resolving within minutes to an hour. However, if not actively managed, it can contribute to the progressive occlusal changes described in the next section.

Progressive Occlusal Changes: The Long-Term Clinical Evidence

This is the most clinically significant - and most commonly omitted - aspect of MAS therapy. The evidence is now unambiguous: with multi-year use, MAS devices produce measurable, progressive changes to the bite that do not plateau.

The Landmark Pliska et al. Study (2014)

The most cited long-term dataset comes from Pliska BT, Nam H, Chen H, Lowe AA, and Almeida FR, published in the Journal of Clinical Sleep Medicine in 2014. This retrospective study examined adults treated for primary snoring or mild to severe OSA with MAS for a minimum of 8 years.

A total of 77 patients (average age at start of treatment: 47.5 ± 10.2 years, 62 males) were included, with an average treatment length of 11.1 ± 2.8 years.

The findings were striking: over the total treatment interval there was a significant (p < 0.001) reduction in overbite (2.3 ± 1.6 mm), overjet (1.9 ± 1.9 mm), and mandibular crowding (1.3 ± 1.8 mm). Additionally, a corresponding significant (p < 0.001) increase of mandibular intercanine (0.7 ± 1.5 mm) and intermolar (1.1 ± 1.4 mm) width as well as incidence of anterior crossbite and posterior open bite was observed.

Critically, the changes did not stabilise. After an average observation period of over 11 years, clinically significant changes in occlusion were observed and were progressive in nature. Rather than reaching a discernible end-point, the dental side effects of MAS therapy continue with ongoing MAS use. This finding - that there is no apparent ceiling to occlusal change - is the single most important reason why structured long-term monitoring is non-negotiable.

Confirmation from Systematic Reviews and Meta-Analyses

The Pliska findings have been replicated and extended across multiple systematic reviews. A 2025 meta-analysis by Chen et al., published in the Journal of Prosthodontics and incorporating 42 studies, confirmed that long-term OA treatment was associated with a significant decrease in overbite (0.87 mm, 95% CI: 0.69–1.05) and overjet (0.86 mm, 95% CI: 0.69–1.03). The same analysis found a significant retroclination of the upper incisors (U1-SN, 2.58°, 95% CI: 1.07–4.08) and proclination of the lower incisors (L1-MP, −2.67°, 95% CI: −3.78–1.56).

A 2019 systematic review with meta-regression published in the European Journal of Orthodontics analysed 21 studies with follow-up between 2 and 11 years and found that the meta-regression analysis showed that the side effects were influenced by the therapy duration for all parameters (P < 0.05). The authors concluded that MAD therapy produces time-related dental and skeletal side effects. After a long period of treatment, the dental side effects are clinically relevant and therefore the clinician should inform the patients about this issue. Since the side effects are progressive, patients need to be continuously monitored over time.

A 2024 systematic review published in Sleep Medicine (Rao et al.) including 34 studies confirmed in meta-analysis that the meta-analysis showed a gradual decrease in overjet and overbite with treatment duration with long-term use of MADs for the treatment of OSA. Upper and lower incisors retroclined and proclined, respectively.

Why Occlusal Changes Occur: The Biomechanical Mechanism

One force is labially directed to the mandibular incisors and the other is palatally directed to the maxillary incisors. It has been hypothesised that this may change the inclination and position of teeth, affect the position of the mandible, and increase the loading to the craniomandibular complex.

An alternative (and not mutually exclusive) explanation has been proposed: it may not be the teeth moving with time but rather a persistent posturing forward of the mandible. It is recognised that mornings after wearing an MAD, patients may have a difficult time posturing the mandible back to the normal occlusion. If not addressed by the patient or dental sleep specialist, this could eventuate in an irreversible anterior mandibular position with altered occlusion.

Both mechanisms - tooth movement driven by sustained biomechanical forces, and persistent mandibular repositioning - likely operate simultaneously and cumulatively over years of nightly use.

Predictors of Greater Occlusal Change

Not all patients experience the same degree of change. Research published in the Journal of Clinical Sleep Medicine (Maruyama et al.) found that a larger reduction in overjet of ≥ 1 mm was associated with treatment duration, use frequency, and mandibular advancement of the OAs. In addition to these predictive factors, the number of teeth was correlated with the amount of overjet reduction. Patients with fewer maxillary teeth, longer treatment duration, higher nightly compliance, and greater degrees of mandibular advancement are at elevated risk for more pronounced occlusal change.

A 2025 study published in BMC Oral Health using 3D digital cast superimposition found that over the treatment period, overjet and overbite decreased, with increased maxillary palatal inclination, distal tooth translation in the anterior/posterior segments, and palatal movement of the anterior segment. Wing appliances demonstrated greater reductions in overjet and overbite, maxillary posterior segment extrusion, and mesio-buccal translation in mandibular segments. This suggests that device design itself is a modifiable risk factor.

Mitigation Strategies: Protecting the Bite During Long-Term MAS Use

The good news is that the evidence base supports several practical, clinician-guided strategies that meaningfully reduce the rate and severity of occlusal change.

1. Conservative Titration

Research has shown that, in most patients with mild to moderate OSA, advancement of 50% of the patient's range of motion is equally as effective as a 75% titration. This "less is more" principle - advancing the mandible only as far as required to achieve therapeutic efficacy - is the single most impactful way to reduce long-term occlusal side effects.

2. Morning Jaw Exercises

Effective strategies include jaw stretching exercises, adjustments to the MAD device, and palliative care. To reduce risks, it is recommended to perform stretching exercises for a total of one minute every morning after removing the MAD device.

The American Academy of Dental Sleep Medicine (AADSM) recommends structured morning jaw exercises as first-line management for bite changes. Isometric and passive jaw stretching exercises include instructing patients to move the mandible against resistance both vertically and laterally and to stretch the mandibular range of motion assisted by the fingers, targeting the masticatory muscles. These have been shown to decrease the level of discomfort and improve adherence to OAT.

3. Morning Occlusal Guide (AM Aligner)

For patients experiencing persistent morning malocclusion, a morning occlusal guide (MOG) - a small thermoplastic device worn for 5–10 minutes after removing the MAS - can guide the condyle back to its habitual position. Commonly, the dentist will suggest over-the-counter pain relief, jaw exercises to do each morning, or can make you a small device called a morning occlusal guide, which you use after you take your oral appliance out in the morning to guide your jaw back to its normal position.

Morning occlusal guides are considered first-line treatment for decreased overjet and overbite and are widely used.

4. Structured Dental Monitoring

Considering the chronic nature of obstructive sleep apnoea and that oral appliance use might be a lifelong treatment, a thorough customised follow-up should therefore be undertaken to detect possible side effects on craniofacial complex. It is also important to provide adequate information to patients regarding these possible changes, especially to those in whom larger occlusal changes are to be expected or in whom they are unfavourable.

At Smile Solutions Melbourne, regular dental review appointments include bite assessment, dental cast or digital scan comparison over time, TMJ palpation, and review of morning symptom diaries. These check-ins are not optional extras - they are the clinical mechanism by which progressive changes are detected early, before they become clinically irrelevant or irreversible.

(For a detailed explanation of the diagnostic tools used to monitor jaw and bite changes, see our guide on [How TMD, Bruxism, and Sleep Apnoea Are Diagnosed: From Clinical Exam to Sleep Study].)

Device Maintenance: Protecting Your Investment

Daily and Weekly Cleaning Protocol

Bacterial buildup represents the most significant risk of inadequate mouthguard hygiene. Your mouth naturally contains millions of bacteria, and during sleep, saliva production decreases, creating an ideal environment for bacterial growth on your device.

The recommended cleaning protocol is:

1. Daily: Rinse the device immediately upon removal each morning. Clean with a soft-bristled toothbrush and mild, non-abrasive soap or a dedicated oral appliance cleaner.

2. Weekly: Soak in a dental appliance cleaning solution (such as Retainer Brite®) or diluted white vinegar for 20–30 minutes to remove biofilm and mineral deposits.

3. Storage: When you're not using your oral sleep appliance, store it in a clean, dry container that is vented to allow air to circulate and prevent bacteria from growing. Avoid leaving your device in direct sunlight or heat, as this can warp or damage the material.

4. Avoid: Toothpaste (which is abrasive and scratches the device surface, creating bacterial harbourage sites), hot water (which can warp thermoplastic components), and bleach-based products.

Clean your teeth carefully before putting the MRA in your mouth. With good dental care, the MRA does not affect your teeth. Any gum problem or tooth decay could get worse because the MRA covers the teeth and gums, and saliva cannot reach them.

Device Lifespan and Replacement Cycles

Device longevity directly correlates with maintenance quality. Well-maintained sleep apnoea treatment devices can last 3–7 years, whilst poorly maintained appliances may require replacement within 12–18 months.

Several factors accelerate device wear:

• Bruxism: Patients who grind their teeth nightly place significantly greater mechanical stress on the device material. Bruxism-related wear can substantially shorten device lifespan, particularly for thermoformed dual-laminate appliances.
• Material type: 3D-printed nylon appliances (such as those fabricated at Smile Solutions Melbourne using CAD/CAM technology) generally demonstrate superior durability compared to soft thermoplastic devices, resisting deformation and surface degradation more effectively over time.
• Occlusal change: As the bite shifts over years of MAS use, the original fit of the device changes. A device that no longer accurately fits the dentition will be less effective therapeutically and may apply uneven forces, potentially accelerating further occlusal change.

Most sleep apnoea oral appliances are designed to last several years with proper care. However, if you notice significant wear or the appliance no longer fits as well as it used to, it may be time for a replacement.

(For a detailed comparison of device materials and designs, see our guide on [Occlusal Splints vs. Mandibular Advancement Splints for Bruxism: Choosing the Right Device].)

The Role of Regular Dental Monitoring in Long-Term MAS Therapy

What Should Monitoring Include?

A structured long-term monitoring programme for MAS patients should include the following at regular intervals (typically every 6–12 months):

When to Escalate

The present findings make it clear that many of the significant dental changes that occur will continue to progress over the duration of treatment, and as MAS treatment of OSA will continue indefinitely, the prudent clinician will be aware of these changes and discuss them openly with patients in their care.

Red flags that warrant urgent clinical review include:

• Persistent morning bite change that does not self-resolve within 30–60 minutes
• New or worsening TMJ pain, clicking, or locking (see our guide on [What Is TMD? Understanding Temporomandibular Joint Disorders])
• Visible tooth movement or spacing changes
• Device no longer seating correctly on the teeth
• Return of snoring or sleep apnoea symptoms, which may indicate the device has been rendered ineffective by occlusal drift

Over a long time, your lower jaw position can sometimes change and sit forward from its original position. If you have any concerns or notice any change in how the teeth meet (the bite), stop wearing the MRA and contact the dental sleep department about this matter.

Balancing Risk and Benefit: The Clinical Perspective

It is important to contextualise these side effects within the broader risk-benefit equation. Side effects of MAS use over long periods are common but mild and well tolerated by most patients, and dentofacial changes are negligible in shorter-term studies. The more significant changes documented by Pliska et al. and confirmed in subsequent systematic reviews emerge over the 5–11 year timeframe.

Crucially, the alternative - untreated obstructive sleep apnoea - carries far greater health risks: cardiovascular disease, stroke, cognitive impairment, and metabolic dysfunction. (See our guide on [Obstructive Sleep Apnoea: What It Is, Why It Happens, and Why Your Dentist Can Help] for a full discussion of OSA's systemic health consequences.)

The clinical consensus, reflected in guidelines from the American Academy of Sleep Medicine (AASM) and the American Academy of Dental Sleep Medicine (AADSM), is that the occlusal side effects of MAS therapy are manageable with appropriate monitoring and do not, in most patients, outweigh the substantial therapeutic benefits. The risk of developing pain and function impairment of the temporomandibular complex appeared limited with long-term mandibular advancement splint use.

What is not acceptable is uninformed consent - proceeding with MAS therapy without patients understanding that progressive bite changes are an expected feature of decade-long treatment, not an unexpected complication.

Key Takeaways

• Transient side effects (jaw soreness, excess salivation, dry mouth, morning bite changes) are common in the first weeks of MAS therapy and typically resolve with acclimatisation and device adjustment.
• Progressive occlusal changes - including measurable reductions in overbite and overjet - are an expected feature of long-term MAS use, confirmed across multiple systematic reviews and a landmark 11-year longitudinal study. These changes do not plateau and continue with ongoing device use.
• Conservative titration (advancing the mandible only as far as needed for therapeutic efficacy) and daily morning jaw exercises are evidence-based strategies that meaningfully reduce the rate of occlusal change.
• Morning occlusal guides (AM Aligners) are a first-line clinical tool for managing morning malocclusion and preventing cumulative bite drift.
• Regular dental monitoring - including dental cast comparison, TMJ assessment, and device inspection at 6–12 monthly intervals - is not optional; it is the primary mechanism by which side effects are detected early and managed before they become irreversible.
• Device maintenance (daily cleaning, weekly deep cleaning, proper storage, and timely replacement every 3–7 years) protects both oral health and therapeutic efficacy.

Conclusion

Mandibular advancement splint therapy is a highly effective, evidence-based treatment for OSA, snoring, and bruxism - but it is a lifelong commitment that requires an equally long-term approach to care. The science is clear: progressive occlusal changes accumulate over years of nightly use, device materials degrade, and the jaw and bite require active monitoring to preserve both oral health and therapeutic effectiveness.

What separates excellent MAS care from merely adequate care is the quality of the monitoring programme surrounding the device. At Smile Solutions Melbourne, long-term MAS management is built into the treatment model from the first appointment - not added as an afterthought when problems arise.

If you are currently wearing a mandibular advancement splint and have not had a formal bite assessment in the past 12 months, that review is overdue. If you are considering MAS therapy for the first time, understanding this long-term picture before you begin is part of making a genuinely informed treatment decision.

(For a complete overview of the patient journey at Smile Solutions Melbourne - from initial assessment through to long-term management - see our guide on [Getting Your Mandibular Advancement Splint at Smile Solutions Melbourne: A Step-by-Step Patient Guide].)

Smile Solutions has been providing dental care from Melbourne's CBD since 1993. Located at the Manchester Unity Building, Level 1 and 10, 220 Collins Street, Smile Solutions brings together 60+ clinicians - including 25+ board-registered specialists - who have cared for over 250,000 patients. No referral is required to book a specialist appointment. Call 13 13 96 or visit smilesolutions.com.au to arrange your TMD and sleep treatment consultation.

References

• Pliska BT, Nam H, Chen H, Lowe AA, Almeida FR. "Obstructive Sleep Apnea and Mandibular Advancement Splints: Occlusal Effects and Progression of Changes Associated with a Decade of Treatment." Journal of Clinical Sleep Medicine, 2014;10(12):1285–1291. https://doi.org/10.5664/jcsm.4278

• Chen Y et al. "Dentoskeletal Changes of Long-Term Oral Appliance Treatment in Patients with Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis." Journal of Prosthodontics, 2025. https://doi.org/10.1111/jopr.13946

• Rao S et al. "Dental and Skeletal Changes of Long-Term Use of Mandibular Advancement Devices for the Treatment of Adult Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis." Sleep Medicine, 2024. https://pubmed.ncbi.nlm.nih.gov/39174171/

• Alessandri-Bonetti G et al. "Dental and Skeletal Long-Term Side Effects of Mandibular Advancement Devices in Obstructive Sleep Apnea Patients: A Systematic Review with Meta-Regression Analysis." European Journal of Orthodontics, 2019;41(1):89–96. https://doi.org/10.1093/ejo/cjy043

• Takizawa C et al. "The Impact of Oral Appliance Therapy and Mandibular Advancement Devices on Jaw Function Symptoms in Sleep Apnea: A Narrative Review." Journal of Oral and Maxillofacial Anesthesia, 2024. https://joma.amegroups.org/article/view/6727/html

• Cunha TCA et al. "Side Effects of Mandibular Advancement Splints for the Treatment of Snoring and Obstructive Sleep Apnea: A Systematic Review." Dental Press Journal of Orthodontics, 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC6150709/

• Robertson C, Herbison P, Harkness M. "Dental and Occlusal Changes During Mandibular Advancement Splint Therapy in Sleep Disordered Patients." European Journal of Orthodontics, 2003;25(4):371–376. https://doi.org/10.1093/ejo/25.4.371

• Maruyama T et al. "Predictors of Side Effects with Long-Term Oral Appliance Therapy for Obstructive Sleep Apnea." Journal of Clinical Sleep Medicine, 2018. https://doi.org/10.5664/jcsm.6896

• American Academy of Dental Sleep Medicine (AADSM). "Management of Side Effects of Oral Appliance Therapy." Journal of Dental Sleep Medicine. https://aadsm.org/journal/special_article_issue_44.php

• Ford ML, Vorona RD, Ware JC. "An Alternative Cause for Long Term Changes with Mandibular Advancement Devices." Journal of Clinical Sleep Medicine, 2015;11(4):501. https://pmc.ncbi.nlm.nih.gov/articles/PMC4365467/

• Guy's and St Thomas' NHS Foundation Trust. "Mandibular Repositioning Appliance (MRA)." Patient Information, 2024. https://www.guysandstthomas.nhs.uk/health-information/mandibular-repositioning-appliance-mra