--- title: Mandibular Advancement Splints Explained: How They Work, Who They're For, and What to Expect canonical_url: https://directory.smilesolutions.com.au/dental-sleep-health/tmd-bruxism-sleep-disordered-breathing-treatment/mandibular-advancement-splints-explained-how-they-work-who-theyre-for-and-what-to-expect/ category: description: geography: city: state: country: metadata: phone: email: website: publishedAt: --- # Mandibular Advancement Splints Explained: How They Work, Who They're For, and What to Expect ## Mandibular Advancement Splints Explained: How They Work, Who They're For, and What to Expect For millions of Australians living with obstructive sleep apnoea (OSA), habitual snoring, or bruxism-related jaw pain, the path to effective treatment often leads to a single, deceptively simple-looking device: the mandibular advancement splint (MAS). Yet simplicity of appearance belies considerable clinical sophistication. A well-fabricated, properly titrated MAS is a precision medical appliance - one that works by exploiting the biomechanical relationship between jaw position and upper airway patency, and whose outcomes are directly shaped by the quality of diagnosis, the accuracy of fabrication, and the rigour of the titration process. This article provides a definitive, evidence-grounded explanation of MAS therapy: how it works at a physiological level, who is - and is not - a good candidate, how modern devices are fabricated using CAD/CAM and 3D-printing technology, what the titration process involves, and what realistic outcomes patients should expect for snoring, OSA, and bruxism. It is intended as the authoritative clinical reference for anyone considering this treatment in Melbourne. --- ## What Exactly Is a Mandibular Advancement Splint? A mandibular advancement splint is a prescription custom-made medical device worn in the mouth used to treat sleep-related breathing disorders including obstructive sleep apnoea, snoring, and TMJ disorders. Commonly used terms include mandibular advancement device (MAD), mandibular repositioning device (MRD), mandibular advancement splint (MAS), and mandibular advancement appliance (MAA). Oral appliances are devices intended to protrude and stabilise the mandible to maintain a patent airway during sleep. A custom oral appliance is "fabricated using digital or physical impressions and models of an individual patient's oral structures" - it is not a prefabricated item that is trimmed, bent, or relined. It is made of biocompatible materials and engages both the maxillary and mandibular arches. This definitional distinction matters enormously. Pre-fabricated, off-the-shelf appliances are less effective and less accepted by patients and therefore should not be used either as a therapeutic option or as a screening tool to predict MAS responders. The clinical evidence consistently favours custom-made devices: custom-made MADs showed marginally greater AHI reduction than ready-made MADs, have longer wearing times and higher adherence rates, and generally have fewer side effects than ready-made MADs. --- ## How a Mandibular Advancement Splint Works: The Mechanism of Action ### The Airway Physics of Jaw Position MAS is an oral appliance which protrudes the mandible in relation to the maxilla, causing movement of soft tissues - the tongue and soft palate - to increase the calibre of the upper airway. This is the core mechanism: by holding the lower jaw in a forward (protruded) position during sleep, the MAS physically tethers the tongue and associated soft tissues away from the posterior pharyngeal wall, preventing the airway collapse that characterises OSA and produces the vibration of snoring. In awake patients, imaging studies have shown that MAS enlarges the upper airway dimensions by specifically increasing the lateral dimensions of the velopharynx. This lateral widening of the throat is the critical structural change - and it explains why the degree of mandibular protrusion matters so much. Further protrusion brings more lateral expansion of the velopharynx, and the dose-dependent effect of mandibular protrusion on reduction of AHI is nonlinear and becomes more pronounced with increased severity of OSA. In addition to mechanical airway widening, MAS is thought to primarily act by advancing the mandible during sleep, though other potential mechanisms such as stimulation of neuromuscular reflex pathways in the oral cavity and alteration of the bite relationship have also been proposed. ### Monobloc vs. Bibloc (Dual-Arch) Designs MAS devices come in two fundamental configurations: - **Monobloc (single-piece):** The upper and lower arches are fused into one fixed unit at a predetermined jaw position. - **Bibloc (dual-piece/duo-bloc):** The upper and lower arch components are separate but connected by an adjustable mechanism, allowing incremental advancement. A bibloc appliance could be preferred over monobloc devices due to the possibility of arranging the mandibular advancement according to the patient's clinical condition and orofacial symptoms. However, bibloc systems necessitate firm control of the anterior mandibular opening via elastics or an anterior screw design. The ongoing debate does not clarify which appliance is superior, and further research is needed to reach consensus. From a practical standpoint, titratable or adjustable appliances allow progressive protrusion of the mandible, and the amount of anteroposterior mandibular movement varies considerably between patients. MAS efficacy is related to the amount of mandibular advancement, and determining the optimal degree of mandibular advancement is the most important step when using MAS therapy successfully. --- ## Who Is a Good Candidate for MAS Therapy? ### Confirmed Indications The American Academy of Sleep Medicine (AASM) and the American Academy of Dental Sleep Medicine (AADSM) recommend that sleep physicians should prescribe sleep apnoea oral appliances for adult patients who need treatment for their primary snoring (without obstructive sleep apnoea) rather than no treatment, and for patients who have obstructive sleep apnoea but are intolerant to CPAP therapy or otherwise prefer alternate therapy. The success of MAD therapy for OSA primarily depends on appropriate patient selection and a comprehensive clinical evaluation. Ideal candidates for MAD treatment include patients with mild to moderate OSA, those who cannot tolerate CPAP, and individuals with favourable anatomical profiles. Pre-treatment evaluations, such as polysomnography and upper airway examinations, are essential to establish an accurate diagnosis and guide therapeutic decisions. MADs are considered the first-line treatment for patients with mild to moderate OSA and those severe patients who cannot tolerate CPAP or surgical treatment. ### Candidacy Assessment: What Clinicians Evaluate Before a MAS is prescribed, a qualified dental sleep medicine practitioner must assess: | Assessment Factor | Clinical Significance | |---|---| | Confirmed OSA diagnosis (AHI from sleep study) | Determines OSA severity and treatment urgency | | Dental health (tooth number, periodontal status) | Device requires adequate dentition for retention | | Jaw range of motion | Sufficient protrusive capacity is needed for effective advancement | | TMJ health | Active TMJ pathology may contraindicate or complicate MAS | | BMI and craniofacial anatomy | Predicts likelihood of treatment response | | Nasal airway patency | High nasal resistance may reduce MAS efficacy | Regarding the dental requirements: patients are typically excluded if there is evidence of periodontal disease, edentulism, or an exaggerated gag reflex. Patients who are edentulous, have severe periodontal disease, or have active, painful TMJ disorders may require alternative treatment pathways or preliminary management before MAS fabrication. For patients presenting with bruxism, the treatment calculus is more nuanced. A standard flat-plane occlusal splint - the traditional bruxism device - does not advance the mandible and therefore cannot address any co-existing airway component. This is clinically significant because research has shown that standard occlusal splints can actually worsen airway obstruction in patients with undiagnosed OSA. (For a detailed comparison of occlusal splints and MAS for bruxism management, see our guide on *Occlusal Splints vs. Mandibular Advancement Splints for Bruxism: Choosing the Right Device*.) --- ## The Fabrication Process: From Impression to Device ### Why Modern Fabrication Technology Matters The accuracy of a MAS is directly tied to how precisely it replicates the patient's dental anatomy and the prescribed jaw relationship. Contemporary practice has shifted significantly toward digital workflows. The combination of 3D printing with digital healthcare workflows, such as CAD/CAM and intraoral or facial scanning, is improving the clinical efficiency of sleep apnoea device manufacture, providing the ability to rapidly prototype and modify designs in response to patient input. 3D printing has emerged as a transformative technology in dental splint fabrication, offering significant advancements in customisation, production speed, material efficiency, and patient comfort. At Smile Solutions Melbourne, the MAS fabrication workflow integrates intraoral digital scanning, CAD/CAM design, and 3D-printed nylon construction - a combination that delivers superior fit accuracy and device durability compared to traditional stone-cast and thermoforming methods. ### The Step-by-Step Fabrication Process 1. **Digital impressions:** Intraoral scanning captures precise three-dimensional models of both dental arches, eliminating the discomfort of traditional alginate impressions and reducing dimensional inaccuracy. 2. **Bite registration:** A construction bite is recorded at the prescribed degree of mandibular protrusion - typically 50–75% of the patient's maximum protrusive capacity as a starting position - and at an appropriate vertical dimension. 3. **CAD design:** Dental software designs the upper and lower splint components in three dimensions, allowing virtual verification of fit, occlusal coverage, and connector positioning before any material is committed. 4. **CAM fabrication:** The device is either milled from a puck of biocompatible material (subtractive manufacturing) or printed layer-by-layer in nylon (PA12) or medical-grade resin (additive manufacturing). Nylon (PA12) and PEEK polymers are established materials in the 3D-printed sleep apnoea device category. 5. **Finishing and quality check:** The device is polished, connectors are fitted, and fit is verified on the digital model before delivery. The digital workflow - intraoral scanning, virtual jaw relation recording, and CAD - eliminates many manual steps and errors, resulting in more accurate splint fit and presumably better therapeutic outcomes. --- ## Titration: The Critical Step Most Patients Don't Know About ### What Is Titration and Why Does It Matter? Titration is the process of incrementally advancing the mandibular position of the MAS until the therapeutic optimum is reached - the point at which airway obstruction is controlled while side effects (jaw soreness, tooth discomfort) remain acceptable. It is arguably the most important phase of MAS therapy, and it is where under-resourced or non-specialist providers most commonly fall short. MAS efficacy is related to the amount of mandibular advancement, and determining the optimal degree of mandibular advancement is the most important step when using MAS therapy successfully. As an analogy, titration of MAS is very similar to CPAP - the amount of pressure required for each patient cannot be pre-determined based on OSA severity or craniofacial characteristics. Research quantifies the target protrusion ranges: the target protrusion for patients with mild, moderate, and severe OSA was 3.5 ± 1.8 mm (38.6% of maximal mandibular protrusion), 5.8 ± 1.9 mm (62.9% of maximal mandibular protrusion), and 5.9 ± 2.2 mm (68.8% of maximal mandibular protrusion), respectively. These figures illustrate that optimal advancement is highly individual and cannot be set arbitrarily. ### The Acclimatisation Period Most patients require a structured acclimatisation period of 4–8 weeks during which they adapt to wearing the device nightly while incremental titration adjustments are made. During this period: - **Jaw soreness** and morning stiffness are common and typically resolve within the first 2–4 weeks - **Excess salivation** is frequently reported in the first 2–3 weeks - **Transient tooth sensitivity** may occur as occlusal forces redistribute - **Morning occlusal changes** - where the bite feels different for 15–30 minutes after waking - are normal and expected The titration process is crucial for ensuring the best device function and minimising side effects such as temporomandibular joint (TMJ) pain, occlusal changes, and increased salivation. Following the titration and acclimatisation period, a follow-up sleep study (either polysomnography or validated home sleep testing) is performed with the device in situ to objectively confirm therapeutic efficacy. This is a non-negotiable step in responsible MAS care - subjective improvement alone is insufficient to confirm that OSA has been adequately controlled. --- ## What Outcomes Can Patients Realistically Expect? ### For Obstructive Sleep Apnoea Mandibular advancement splint therapy emerged as an effective therapy for obstructive sleep apnoea in the mid-1990s and is now the leading treatment alternative for OSA. The evidence for AHI reduction is robust. In a landmark randomised controlled trial published in the *American Journal of Respiratory and Critical Care Medicine*, subjective improvements with the MAS were reported by the majority of patients (96%), with significant improvements in AHI (30 ± 2/h versus 14 ± 2/h, p < 0.0001), minimum oxygen saturation, and arousal index. A 2024 meta-analysis published in *Otolaryngology–Head and Neck Surgery* found that oral devices could be effective in mitigating severe sleep apnoea, with an estimated 66% reduction in AHI associated with the use of a mandibular advancement device. Long-term data from the ORCADES study (5-year follow-up, *Journal of Clinical Sleep Medicine*) show that MAD treatment remained effective over 5-year follow-up in patients with mild to severe OSA who were intolerant of or refused CPAP. Efficacy in terms of AHI reduction did decline over time, but despite the slight worsening of respiratory parameters, sleepiness and symptoms such as fatigue and morning headache remained well controlled, and sleep quality showed marked and sustained improvements during long-term MAD therapy. Critically, while CPAP produces greater raw AHI reduction, MAS therapy improves blood pressure, daytime somnolence, driving risk, and quality of life to the same extent as CPAP, including in patients with severe OSA. It is hypothesised that the reduced efficacy of MAS when compared to CPAP may be offset by improved patient tolerance and adherence, leading to similar benefits in neurobehavioural and cardiovascular outcomes. (For a head-to-head evidence comparison of MAS and CPAP, see our guide on *Mandibular Advancement Splint vs. CPAP: Which Sleep Apnoea Treatment Is Right for You?*) ### For Snoring MAS is highly effective for primary snoring. The AASM/AADSM guideline recommends oral appliance therapy as an effective treatment for primary snoring in adults; however, because snoring is a cardinal symptom of OSA, a diagnosis of primary snoring should be rendered by a sleep physician prior to treatment initiation. In clinical practice, snoring reduction is often the most immediately noticeable outcome - partners frequently report dramatic improvement within the first nights of device use. (See also: *Does Snoring Always Mean Sleep Apnoea? Understanding Primary Snoring vs. OSA*.) ### For Bruxism A MAS worn by a bruxer provides a protective occlusal surface between the upper and lower teeth, preventing direct tooth-to-tooth grinding contact. However, the evidence on whether MAS *reduces* bruxism activity - as opposed to simply protecting the teeth - is more nuanced. The key advantage of MAS over a standard flat-plane occlusal splint in a bruxing patient is that the MAS simultaneously manages any co-existing airway component. Because sleep bruxism is strongly associated with sleep-disordered breathing, an appliance that addresses both the airway and tooth protection represents the more complete treatment solution for the majority of bruxism patients. (See our guide on *The TMD–Bruxism–Sleep Apnoea Connection* for the clinical rationale.) ### Realistic Response Rates Up to 70% of patients will experience a partial or complete treatment response. Complete response - defined as AHI reduced to under 5 events/hour - is more common in mild-to-moderate OSA. The proportion of patients with a response at the AHI < 10 events/h threshold was significantly higher in patients with mild or moderate versus severe OSA (67% and 52% vs 28%, respectively). Patients who are less likely to achieve complete response with MAS alone include those with severe OSA, significant obesity, or predominantly supine-independent apnoea. These patients may still benefit substantially from MAS - particularly given the adherence advantage over CPAP - or may be candidates for combination therapy. --- ## Key Takeaways - **MAS works by mechanically advancing the mandible**, which moves the tongue and soft palate forward, increasing the lateral dimensions of the upper airway and preventing the collapse that causes OSA and snoring. - **Custom-fabricated, titratable MAS devices consistently outperform off-the-shelf alternatives** in efficacy, adherence, and side-effect profile - making specialist fabrication essential, not optional. - **Titration is the most critical phase of MAS therapy.** The optimal degree of mandibular advancement is individual and cannot be pre-set; it must be determined through incremental adjustment and confirmed by objective sleep testing. - **MAS produces equivalent improvements in quality of life, blood pressure, and daytime functioning compared to CPAP**, despite lower raw AHI reduction - largely because patients wear MAS more consistently. - **Accurate diagnosis before device fabrication is non-negotiable.** Prescribing a standard occlusal splint to a patient with undiagnosed OSA, or fitting a MAS without a confirmed diagnosis, risks both under-treatment and avoidable complications. --- ## Conclusion A mandibular advancement splint is far more than a mouthguard. When correctly indicated, precisely fabricated, and carefully titrated, it represents one of the most evidence-supported, patient-tolerated, and clinically versatile tools in the management of sleep-disordered breathing and bruxism. The difference between a device that transforms a patient's sleep and one that sits in a drawer lies almost entirely in the quality of the clinical process surrounding it - from accurate diagnosis to digital fabrication to structured follow-up. At Smile Solutions Melbourne, MAS therapy is delivered within an integrated diagnostic and treatment framework that combines clinical jaw and airway assessment, CAD/CAM and 3D-printed device fabrication, structured titration, and post-treatment sleep study confirmation. This is the standard of care that the evidence supports - and the standard that patients deserve. To understand the full patient journey at Smile Solutions, see *Getting Your Mandibular Advancement Splint at Smile Solutions Melbourne: A Step-by-Step Patient Guide*. For long-term considerations including side effects and device maintenance, see *Long-Term Care and Side Effects of Mandibular Advancement Splints: What Every Patient Should Know*. --- 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 - Ramar, K., Dort, L.C., Katz, S.G., et al. "Clinical Practice Guideline for the Treatment of Obstructive Sleep Apnea and Snoring with Oral Appliance Therapy: An Update for 2015." *Journal of Clinical Sleep Medicine*, 2015. https://doi.org/10.5664/jcsm.4858 - Mohammadieh, A., Tong, B., De Chazal, P., and Cistulli, P.A. "Innovations in Mandibular Advancement Splint Therapy for Obstructive Sleep Apnoea." *Frontiers in Sleep*, 2023. https://doi.org/10.3389/frsle.2023.1144327 - Cistulli, P.A., Gotsopoulos, H., Marklund, M., and Lowe, A.A. "Treatment of Snoring and Obstructive Sleep Apnea with Mandibular Repositioning Appliances." *Sleep Medicine Reviews*, 2004. - Gotsopoulos, H., Chen, C., Qian, J., and Cistulli, P.A. "A Randomized, Controlled Study of a Mandibular Advancement Splint for Obstructive Sleep Apnea." *American Journal of Respiratory and Critical Care Medicine*, 2002. https://doi.org/10.1164/ajrccm.163.6.2004213 - Lo Giudice, A., La Rosa, S., Palazzo, G., and Federico, C. "Diagnostic and Therapeutic Indications of Different Types of Mandibular Advancement Design for Patients with Obstructive Sleep Apnea Syndrome." *Diagnostics*, 2024. https://doi.org/10.3390/diagnostics14171915 - Sutherland, K., and Cistulli, P.A. "Mandibular Advancement Splints for the Treatment of Sleep Apnea Syndrome." *Swiss Medical Weekly*, 2011. - Almeida, F.R., Mulgrew, A., Ayas, N., et al. "Mandibular Advancement Splint as Short-Term Alternative Treatment in Patients with Obstructive Sleep Apnea Already Effectively Treated with Continuous Positive Airway Pressure." *Journal of Clinical Sleep Medicine*, 2013. https://doi.org/10.5664/jcsm.2576 - Sutherland, K., Vanderveken, O.M., Tsuda, H., et al. "Mandibular Advancement Device Use in Obstructive Sleep Apnea: ORCADES Study 5-Year Follow-Up Data." *Journal of Clinical Sleep Medicine*, 2021. https://doi.org/10.5664/jcsm.9308 - Aarab, G., Lobbezoo, F., Hamburger, H.L., and Naeije, M. "The Effect of Gradually Increased Mandibular Advancement on the Efficacy of an Oral Appliance in the Treatment of Obstructive Sleep Apnea." *Journal of Clinical Sleep Medicine*, 2010. https://doi.org/10.5664/jcsm.8556 - Abdelwahab, M., Patel, P., Okland, T., et al. "Efficacy and Adherence of Different Mandibular Advancement Devices Designs in Treatment of Obstructive Sleep Apnea: A Systematic Review and Meta-analysis." *Journal of Oral and Maxillofacial Surgery*, 2025. https://doi.org/10.1016/j.joms.2025.01.005 - Villanueva, J.M.A., et al. "Efficacy of Mandibular Advancement Devices in the Treatment of Mild to Moderate Obstructive Sleep Apnea: A Systematic Review." *MDPI Dentistry Journal*, 2025. https://www.mdpi.com/2673-8937/5/4/49 - American Academy of Sleep Medicine (AASM). "AASM and AADSM Issue New Joint Clinical Practice Guideline for Oral Appliance Therapy." *AASM Press Release*, 2015. https://aasm.org/aasm-and-aadsm-issue-new-joint-clinical-practice-guideline-for-oral-appliance-therapy/