Occlusal Splints vs. Mandibular Advancement Splints for Bruxism: Choosing the Right Device product guide

Occlusal Splints vs. Mandibular Advancement Splints for Bruxism: Choosing the Right Device

Every year, thousands of Australians are fitted with an occlusal splint for teeth grinding - and a significant proportion of them have undiagnosed obstructive sleep apnoea (OSA). This is not a minor clinical oversight. The research evidence is unambiguous: prescribing the wrong splint to the wrong patient does not simply fail to help - it can actively make a serious sleep disorder worse. The decision between a flat-plane occlusal splint and a mandibular advancement splint (MAS) for bruxism management is therefore not merely a matter of device preference. It is a clinical decision that must be anchored in a thorough understanding of why a patient is grinding, what else may be happening while they sleep, and what the underlying cause demands in terms of treatment.

This article provides a definitive, evidence-based comparison of occlusal splints and MAS as bruxism management tools - covering mechanism of action, efficacy evidence, the critical airway safety issue, splint materials, and the diagnostic logic that determines which device is right for which patient.

What Each Device Does: Mechanism of Action

The Flat-Plane Occlusal Splint

An occlusal appliance - also referred to as a bite guard or bite splint - is a custom-fabricated hard or soft acrylic device that fits over the occlusal and incisal surfaces of either the maxillary or mandibular teeth.

Michigan-type stabilisation splints are characterised by being made from hard acrylic resin, covering all teeth in the splint-bearing jaw, with the posterior teeth of the opposing jaw having even and simultaneous contact with the splint on a flat surface. The therapeutic rationale for stabilisation splint use in individuals with bruxism is the prevention or limitation of dental damage. Wearing a stabilisation splint results in a change of functional muscular patterns due to an increase in vertical distance between the upper and lower jaw, leading to altered load distribution in the TMJ and jaw muscles.

Critically, the occlusal splint does not advance the mandible or engage the airway. Its mechanism is entirely passive and protective: it redistributes bite forces across a sacrificial acrylic surface rather than directly across tooth enamel, and may provide some degree of sensorimotor feedback that temporarily modulates grinding behaviour.

The Mandibular Advancement Splint (MAS)

Mandibular advancement splint (MAS) therapy is the leading alternative to continuous positive airway pressure (CPAP) therapy for the treatment of obstructive sleep apnoea. A MAS is an oral appliance which advances the mandible in relation to the maxilla, thus increasing airway calibre and reducing airway collapsibility.

Mandibular advancement devices induce mandibular advancement, increasing upper airway cross-sectional area and volume. In doing so, the MAS simultaneously provides a degree of occlusal separation - offering tooth protection - while also addressing the airway mechanics that may be driving sleep-related grinding in the first place.

The Efficacy Evidence: What the Research Actually Shows

Occlusal Splints and Bruxism: Protective, Not Curative

The clinical literature on occlusal splints for sleep bruxism is sobering. There is insufficient evidence to either support or refute the use of occlusal splints for treating patients with tooth grinding or clenching during sleep. There is not sufficient evidence to state that the occlusal splint is effective for treating sleep bruxism. Indication of its use is questionable with regard to sleep outcomes, but it may be that there is some benefit with regard to tooth wear. This finding, from the Cochrane systematic review by Macedo et al. (2007), has been consistently replicated.

Although many studies claim that splints reduce nocturnal bruxism, others have shown that this does not occur, and some patients show increased jaw muscle force while wearing a splint. Furthermore, hard acrylic-resin stabilisation splints are more effective compared to soft splints. Soft-resin splints are more difficult to adjust compared to hard acrylic-resin devices and may increase clenching behaviour in some patients. Studies reveal that some patients may have increased EMG activity when they wear an occlusal splint during sleep, particularly when the splints are soft or do not fit well.

The bottom line: occlusal splints provide clinically meaningful tooth protection and can reduce jaw muscle discomfort, but they do not reliably reduce the underlying bruxism behaviour itself.

MAS and Bruxism: A Greater Effect on Muscle Activity

When researchers directly compared the two devices using objective polysomnographic measurement, a clear pattern emerged. Self-reports for sleep quality and comfort showed a mild advantage of the occlusal splint when compared to the MAS. In the short term, the comfort of the oral device seemed to influence sleep quality in sleep bruxism individuals. However, despite the slightly higher degree of comfort offered by the occlusal splint, the MAS induced a greater effect on the RMMA index. (Abe et al., International Journal of Prosthodontics, 2022.)

The RMMA (rhythmic masticatory muscle activity) index is the electromyographic marker of sleep bruxism - a more objective measure than patient self-report. The finding that MAS produces greater RMMA reduction than an occlusal splint, despite being rated as slightly less comfortable initially, is clinically significant.

This is further supported by research into the OSA–bruxism connection. Some studies report that around half of individuals with OSA also have sleep bruxism, suggesting that SB is a common comorbidity of OSA, and that there is a close association between the two conditions. Although the underlying mechanism of the association between OSA and SB is still unclear, previous studies suggested that the occurrence of RMMA might be related to recurrent respiratory events and sleep arousals in OSA. When the MAS addresses airway obstruction, it may simultaneously reduce the arousal-driven grinding episodes that are secondary to those obstructive events. In a cohort study of 38 OSA patients, the RMMA index decreased significantly with both CPAP and mandibular advancement appliance therapies (p < 0.05). (Sleep and Breathing, 2023.)

The Critical Safety Issue: Why an Occlusal Splint Can Worsen OSA

This is the most clinically important distinction in this entire article, and the one most frequently overlooked in general dental practice.

Obstructive sleep apnoea is a contraindication to the use of an occlusal splint. Occlusal splints can worsen obstructive sleep apnoea. Patients with sleep bruxism and obstructive sleep apnoea who need protection for their teeth should use a mandibular advancement device. (StatPearls / NCBI Bookshelf, 2024.)

The mechanism by which a standard maxillary occlusal splint worsens OSA is well described. Occlusal splints, which are used for TMD or masticatory muscle problems, might cause worsening of OSA by moving the mandible backward, narrowing the airway. By increasing vertical dimension without advancing the mandible, the splint can posteriorly rotate the jaw and reduce the posterior airway space - the opposite of what is needed in a patient with OSA.

The quantitative evidence is alarming. A pilot study of 10 patients with OSAHS found that a maxillary occlusal splint increased the AHI by more than 50% in half of the patients, likely by reducing the intraoral space and changing the tongue position during sleep. Another group reproduced the direction taken by the pilot study - a risk for exacerbation of breathing in OSAHS patients, but with a milder effect due to different morphologic patient characteristics. Although there is a paucity of data, the potential adverse influence of maxillary occlusal splints on snoring and the respiratory disturbance index cannot be ignored, and clinicians should be cautious and consider the potential medical and dental complications of occlusal splints, especially when sleep bruxism and OSAHS occur in the same patient.

Confirming the clinical direction, Gagnon et al. (2004) found that the percentage of sleeping time with snoring also increased by 40% with the splint. This open study suggested that the use of an occlusal splint is associated with a risk of aggravation of respiratory disturbances.

The TMJ Association summarises the implication clearly: clinicians who want to make a stabilisation splint for their patients should at least inquire about whether obstructive sleep apnoea is a condition they may have.

This is why, at Smile Solutions Melbourne, every patient presenting with bruxism is screened for sleep-disordered breathing before any splint is fabricated. Fitting an occlusal splint without this step is not conservative management - it is incomplete management. (See our guide on How TMD, Bruxism, and Sleep Apnoea Are Diagnosed: From Clinical Exam to Sleep Study for the full diagnostic pathway.)

Choosing the Right Device: A Clinical Decision Framework

The following comparison table summarises the key decision criteria:

The management strategy (diagnostic tests and treatment) should be tailored to the patient's phenotype and comorbidities. In the presence of sleep-disordered breathing, a mandibular advancement appliance or CPAP treatment is preferred over single occlusal splint therapy on the upper jaw.

Patients with comorbid obstructive sleep apnoea and bruxism should utilise a mandibular advancement device to help reduce bruxism-related motor activity.

For patients with confirmed primary (isolated) bruxism - no OSA, no significant snoring, no airway risk factors - a well-adjusted, hard acrylic flat-plane splint remains a clinically appropriate, reversible, and cost-effective tooth protection strategy. For patients with any degree of sleep-disordered breathing, or for those in whom OSA has not yet been excluded, an MAS is the clinically safer and more therapeutically comprehensive choice.

Splint Materials: Matching Material to Clinical Need

The choice of device type is only the first decision. Within each category, material selection has meaningful clinical implications.

Hard Acrylic (PMMA)

The traditional Michigan-type stabilisation splint is fabricated from heat-cured polymethyl methacrylate (PMMA). Splints may be constructed in the dental office or a laboratory and fabricated from hard or soft materials. Hard acrylic-resin stabilisation splints are more effective compared to soft splints. Hard acrylic is highly adjustable, durable, and well-suited to the precise occlusal contacts required for a flat-plane design. Its limitations include bulk, potential brittleness in severe bruxers, and the rigidity that some patients find uncomfortable. Evidence indicates that while 3D-printed splints generally meet ISO standards for flexural strength and wear resistance, their mechanical properties are often 15–30% lower than those of heat-cured PMMA in head-to-head tests.

Thermoformed Dual-Laminate

Many dual laminate night guard styles are thermoformed from laminated sheets. In the dental literature, bilaminar splints are described as being composed of two distinct layers (often described as ethylene-vinyl acetate with soft and harder layers) and formed using vacuum/pressure forming techniques. The bilaminar guard literature specifically discusses protective use in cases of bruxism and attrition-based wear, including protecting restorations.

The dual-laminate design - a soft inner layer for retention and comfort bonded to a hard outer layer for durability - represents a practical middle ground for patients who cannot tolerate the rigidity of full hard acrylic. However, bench testing shows some dual-laminate materials can exhibit edge fracture and localised wear patterns under high simulated loads, emphasising that material choice and contact distribution matter for bruxism appliance longevity. For extreme bruxers, full hard acrylic or a 3D-printed high-strength resin is generally preferable.

3D-Printed Nylon and Photopolymer Resins

The emergence of CAD/CAM-designed, 3D-printed splints represents a significant advance in both precision and patient experience. Even under continuous use and mechanical stress, PA 12 (polyamide/nylon) isn't as susceptible to deformation as acrylic, and it also makes for a more ecologically friendly solution.

Nylon splints are made from medical-grade nylon, a durable, flexible thermoplastic material. Unlike conventional acrylic splints, which are rigid and prone to fractures, nylon splints are semi-flexible and lightweight, offering superior patient comfort and longevity. For MAS fabrication specifically, advanced 3D printing solutions enable the creation of custom-fitted, comfortable, and patient-specific medical devices, significantly improving patient adherence and outcomes in the treatment of OSA and bruxism.

Clinical findings suggest that 3D-printed occlusal splints are at least non-inferior to conventional ones in managing bruxism and TMD, with potential advantages in patient-reported comfort and faster adaptation.

For MAS devices in particular, 3D-printed nylon offers a compelling combination: precise fit from digital impressions, flexibility that reduces jaw soreness during acclimatisation, and durability that supports the long-term use that OSA management requires. At Smile Solutions Melbourne, CAD/CAM and 3D-printed nylon fabrication is used for MAS devices precisely because compliance is the single greatest predictor of treatment success - and comfort drives compliance. (See our guide on Mandibular Advancement Splints Explained: How They Work, Who They're For, and What to Expect for the full fabrication process.)

The Underlying Cause of Grinding Determines the Right Device

The core clinical insight that frames this entire comparison is this: bruxism is not a single disease with a single cause. Although the causes and mechanisms of idiopathic-primary sleep bruxism are unknown, putative candidates include psychological risk factors (e.g., anxiety, stress due to life events, hypervigilance) and sleep physiological reactivity (e.g., sleep arousals with autonomic activity and/or breathing events).

This matters enormously for device selection:

• Stress-driven primary bruxism with no airway involvement: A well-fitted hard acrylic flat-plane splint provides appropriate tooth protection. Adjunctive cognitive-behavioural therapy, physiotherapy, or botulinum toxin for masseter hypertrophy may also be warranted (see our guide on TMD Treatment Options in Melbourne: Splints, Physiotherapy, Botox, and Beyond).

• OSA-driven secondary bruxism: The occurrence of RMMA might be related to recurrent respiratory events and sleep arousals in OSA. Here, an occlusal splint treats the symptom while worsening the cause. An MAS addresses both simultaneously.

• Mixed presentation (bruxism with co-existing OSA or significant snoring): The management of co-occurring sleep-related bruxism and OSA is challenging to prevent compromising the oro-pharyngeal space and breathing efficiency. OSA treatment in the presence of sleep-related bruxism includes CPAP use alone or with an occlusal splint or mandibular advancement device.

• Awake bruxism: This is a distinct clinical entity from sleep bruxism (see our guide on Bruxism Explained: Causes, Types, and the Hidden Dangers of Teeth Grinding). Occlusal splints are not worn during waking hours; management focuses on behavioural strategies, biofeedback, and stress management.

The diagnostic imperative is therefore clear: before any splint is fabricated, the clinician must establish whether OSA is present or at risk. This requires at minimum a structured sleep questionnaire and clinical airway assessment, and in many cases a home sleep test or polysomnography. Skipping this step and defaulting to a standard occlusal splint is a pattern that the research literature explicitly cautions against.

Key Takeaways

• Occlusal splints protect teeth but do not reliably reduce sleep bruxism behaviour, and the Cochrane review (Macedo et al., 2007) found insufficient evidence to support their use for sleep outcomes.
• MAS produces greater reduction in RMMA (the objective electromyographic marker of bruxism) than flat-plane occlusal splints, despite being rated slightly less comfortable initially (Abe et al., International Journal of Prosthodontics, 2022).
• A standard maxillary occlusal splint can increase AHI by more than 50% in OSA patients - making it contraindicated in any patient with undiagnosed or known obstructive sleep apnoea (Gagnon et al., 2004; StatPearls, 2024).
• The right device depends on the underlying cause of grinding: stress-driven primary bruxism may be appropriately managed with a hard acrylic flat-plane splint; OSA-driven secondary bruxism requires an MAS that addresses both the airway and the teeth.
• Material matters: hard acrylic remains the gold standard for adjustability and durability; 3D-printed nylon MAS devices offer superior comfort and compliance for long-term airway management.

Conclusion

Choosing between an occlusal splint and a mandibular advancement splint for bruxism is not a question of which device is universally "better." It is a question of which device is right for a specific patient's clinical picture - one that can only be answered after a thorough assessment that includes airway screening. The evidence is clear that an occlusal splint fitted to a patient with undiagnosed OSA can worsen their sleep disorder significantly, while an MAS in the same patient can protect their teeth and their airway simultaneously.

At Smile Solutions Melbourne, the integrated diagnostic approach - combining clinical jaw and bite examination, airway risk assessment, and when indicated, sleep study referral - ensures that every patient receives the device their underlying condition actually requires, not simply the most commonly prescribed one. Whether you are grinding your teeth from stress, from sleep apnoea, or from a combination of both, the treatment logic must follow the diagnosis.

To explore the full diagnostic pathway before any device is prescribed, see our guide on How TMD, Bruxism, and Sleep Apnoea Are Diagnosed: From Clinical Exam to Sleep Study. For a detailed walkthrough of the MAS fabrication and fitting process at Smile Solutions, see 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

• Macedo CR, Silva AB, Machado MAC, Saconato H, Prado GF. "Occlusal splints for treating sleep bruxism (tooth grinding)." Cochrane Database of Systematic Reviews, 2007, Issue 4. Art. No.: CD005514. https://doi.org/10.1002/14651858.CD005514.pub2

• Abe S, Huynh NT, Rompré PH, de Grandmont P, Landry-Schönbeck A, Landry M-L, Kato T, Kawano F, Lavigne GJ. "Sleep Quality and Comfort Reported by Sleep Bruxism Individuals Wearing the Occlusal Splint and Mandibular Advancement Splint: Revisiting Two Crossover Studies." International Journal of Prosthodontics, 2022;36(2):138–147. https://doi.org/10.11607/ijp.7525

• Gagnon Y, Mayer P, Morisson F, Rompré PH, Lavigne GJ. "Aggravation of respiratory disturbances by the use of an occlusal splint in apneic patients: a pilot study." International Journal of Prosthodontics, 2004;17(4):447–453. PMID: 15382781

• Lavigne GJ, Khoury S, Abe S, Yamaguchi T, Raphael K. "Bruxism physiology and pathology: an overview for clinicians." Journal of Oral Rehabilitation, 2008;35(7):476–494. (Referenced via ScienceDirect Topics overview.)

• 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

• Dal Fabbro C, Lavigne GJ, et al. "Understanding the clinical management of co-occurring sleep-related bruxism and obstructive sleep apnea in adults: A narrative and critical review." Journal of Prosthodontics, 2025. https://doi.org/10.1111/jopr.13966

• Rabel A, et al. "3D printed versus milled stabilization splints for the management of bruxism and temporomandibular disorders: study protocol for a randomized prospective single-blinded crossover trial." Trials, 2024. https://doi.org/10.1186/s13063-024-08437-7

• Patel S, et al. "Three-Dimensionally Printed Splints in Dentistry: A Comprehensive Review." MDPI Dentistry Journal, 2025;13(7):312. https://doi.org/10.3390/dj13070312

• Tinastepe N, et al. "Effects of continuous positive airway pressure and mandibular advancement appliance therapy on sleep bruxism in adults with obstructive sleep apnea: a pilot study." Sleep and Breathing, 2023. https://doi.org/10.1007/s11325-023-02799-z

• Huynh N, Manzini C, Rompré PH, Lavigne GJ. "Weighing the potential effectiveness of various treatments for sleep bruxism." Journal of the Canadian Dental Association, 2007;73(8):727–730. (Referenced via StatPearls, NCBI Bookshelf.) https://www.ncbi.nlm.nih.gov/books/NBK482466/

• Nikolopoulou M, Ahlberg J, Visscher CM, et al. "Effects of Occlusal Stabilization Splints on Obstructive Sleep Apnea: A Randomized Controlled Trial." Journal of Orofacial Pain, 2013. (Summarised by The TMJ Association.) https://tmj.org/stabilization-splints-may-worsen-obstructive-sleep-apnea/