Classification of Occlusal Splints: A Comprehensive Review

Definition

I. Classification According to Okeson (Management of Temporomandibular Disorders and Occlusion, 6th/7th ed.)

A. Stabilization Appliance (Muscle Relaxation Appliance / Michigan Splint)

• Also known as the flat plane splint, centric relation splint, gnathologic splint, or Michigan splint
• Fabricated from hard acrylic resin, usually for the maxillary arch
• Provides bilateral, equal, simultaneous contacts of all opposing teeth in centric relation
• Creates canine or anterior guidance during lateral and protrusive movements
• Indication: Myofascial pain, bruxism, clenching, joint disorders with stable condylar position
• Most commonly used appliance; when properly fabricated, has the least potential for adverse effects
• Mechanism: Eliminates occlusal interferences and allows muscles to function at a physiologically comfortable vertical dimension

B. Anterior Repositioning Appliance (Orthopedic Repositioning Appliance / MORA)

• Guides the mandible into an anterior position on closure
• Used to capture anteriorly displaced disc in disc displacement with reduction
• Farrar (1971) first described the anterior repositioning concept
• Worn full-time initially, then gradually adjusted back toward centric relation
• Risk: Permanent bite changes if worn long-term

C. Other Types (Okeson)

II. Classification According to Dawson (Functional Occlusion: From TMJ to Smile Design, 2007)

1. Permissive Splints (Muscle Deprogrammers)

• Allow the mandible to seat freely into its own position (centric relation) without interference
• Flat, smooth occlusal surface with no cusp indentations
• Michigan splint is the classic example
• Goal: Allow muscles to "deprogram" — eliminate proprioceptive memory of acquired intercuspal position
• Used for: diagnosis, muscle relaxation, occlusal evaluation before irreversible treatment

2. Non-Permissive Splints (Directive Splints)

• Direct or guide the mandible to a specific position
• Contain indentations or ramps that hold the condyle/mandible in a predetermined position
• Anterior repositioning appliance (ARA) is the classic example
• Risk: Can cause permanent mandibular shift if used inappropriately or long-term

3. Pseudo-Permissive Splints

• Appear permissive but are not truly so
• Soft/resilient splints: The viscoelastic material conforms around cusps and actually guides occlusion; may increase EMG muscle activity
• Hydrostatic splint (Aqualizer®): Fluid-filled bilateral reservoirs that distribute force; classified here due to variable functional behavior

III. Classification According to Slavicek (JCO, 1989)

IV. Classification According to Clark (A Textbook of Occlusion, 1988)

1. Flat plane appliances — uniform, flat surface with no cusp guidance
2. Canine-guided appliances — anterior guidance on canines during lateral excursions
3. Balanced occlusion appliances — bilateral balanced occlusal contacts in all excursions
4. Anterior repositioning appliances — mandible held in protruded position

V. Classification According to Ramfjord and Ash (Occlusion, 3rd ed., 1983)

1. Full arch maxillary stabilization splint (Michigan Splint) — hard acrylic, full coverage, centric contacts with anterior guidance
2. Anterior bite plane / Sved splint — covers anterior teeth only; posterior teeth in free space
3. Mandibular full-arch splint — used in selected cases (Class III, deep curve of Spee)

• Freedom from interference in any mandibular movement
• Stable closure contact without deflection
• Appropriate vertical dimension
• Non-interference with phonetics, swallowing, and lip seal

VI. Classification According to Dylina (Journal of Prosthetic Dentistry, 2001)

1. Full coverage hard acrylic stabilization splint — primary workhorse; for bruxism, myofascial pain, TMD
2. Anterior repositioning appliance — for disc displacement with reduction
3. Anterior bite plane — for posterior muscle pain reduction
4. Posterior bite plane — controversial; risk of supraeruption of anterior teeth
5. Soft/resilient splint — short-term use, mild cases, compliance-difficult patients

VII. Classification According to Gray, Davies and Quayle / Dental Update (2018)

Group 1: Partial Occlusal Contact (Relaxation Splints)

• Some but not all teeth contact the splint
• In any mandibular closure position, only limited contacts occur
• Includes: Soft splints, anterior bite planes, Lucia jig, Nociceptive Trigeminal Inhibitor (NTI) device
• Risk: Prolonged use may cause posterior supraeruption (open bite)

Group 2: Full Occlusal Contact in Retruded Arc of Closure (Stabilizing Splints)

• All opposing teeth contact the splint in a stable, reproducible position (centric relation)
• Bilateral, equal, simultaneous contacts
• Includes: Michigan splint, Tanner appliance, centric relation appliance
• Most evidence-supported design for long-term TMD management

Group 3: Full Occlusal Contact in Protrusion (Anterior Repositioning Splints)

• Full occlusal contact but mandible held in a protruded position
• Includes: Anterior repositioning appliance (ARA), Farrar splint
• Used for disc displacement with reduction
• Should not be used long-term due to risk of permanent anterior open bite

VIII. Classification Based on Arch Coverage

IX. Classification Based on Material

X. Classification Based on Coverage (Partial vs Full Arch)

Summary Table of Classifications

References (Vancouver Style)

1. The Academy of Prosthodontics. The Glossary of Prosthodontic Terms: Ninth Edition. J Prosthet Dent. 2017;117(5S):e1-e105.
2. Okeson JP. Management of Temporomandibular Disorders and Occlusion. 7th ed. St Louis: Mosby Elsevier; 2013. p. 373-413.
3. Dawson PE. Functional Occlusion: From TMJ to Smile Design. St Louis: Mosby Elsevier; 2007. p. 379-92.
4. Slavicek R. Relationship between occlusion and temporomandibular disorders: implications for the gnathologist. J Clin Orthod. 1989 Feb;23(2):111-8.
5. Clark GT. Interocclusal appliance therapy. In: Mohl ND, Zarb GA, Carlsson GE, Rugh J, editors. A Textbook of Occlusion. Chicago: Quintessence Publishing; 1988. p. 285-302.
6. Ramfjord SP, Ash MM. Occlusion. 3rd ed. Philadelphia: WB Saunders; 1983. p. 26-28. [Also: Ramfjord SP, Ash MM. Reflections on the Michigan occlusal splint. J Oral Rehabil. 1994;21(5):491-500.]
7. Dylina TJ. A common-sense approach to splint therapy. J Prosthet Dent. 2001;86(5):539-45.
8. Gray RJM, Davies SJ, Quayle AA. Occlusal splints and temporomandibular disorders: why, when, how? Dent Update. 2001;28(4):194-9. [Expanded in: Davies SJ, Gray RJM. Occlusal splints for bruxing and TMD – a balanced approach? Dent Update. 2018;45(10):910-21.]
9. Alqutaibi AY, Aboalrejal AN. Types of occlusal splint in management of temporomandibular disorders (TMD). J Arthritis. 2015;4(4):1000161.
10. Crout DK. Anatomy of an occlusal splint. Gen Dent. 2017 Mar-Apr;65(2):52-9. [PMID: 28253183]
11. Greene CS, Menchel HF. The use of oral appliances in the management of temporomandibular disorders. Oral Maxillofac Surg Clin North Am. 2018;30(3):265-77. [PMID: 29866449]
12. Denardin ACS, do Nascimento LP, Valesan LF, Da Cas CD, Pauletto P, Garanhani RR. Disocclusion guides in occlusal splints on temporomandibular disorders and sleep bruxism: a systematic review. Oral Surg Oral Med Oral Pathol Oral Radiol. 2023;135(1):15-27. [PMID: 36241594]
13. Farrar WB. Characteristics of the condylar path in internal derangements of the TMJ. J Prosthet Dent. 1978;39(3):319-23.
14. Lerman MD. The hydrostatic appliance: a new approach to treatment of the TMJ pain-dysfunction syndrome. J Am Dent Assoc. 1974;89(6):1343-50.

• The hard stabilization (Michigan) splint has the strongest evidence base and is recommended as the first-line appliance for most TMD and bruxism cases
• Soft splints may paradoxically increase masseter/temporalis EMG activity in a subset of patients and are best reserved for short-term use
• Anterior repositioning splints should be used cautiously and for limited periods due to risk of irreversible occlusal changes
• Partial-coverage splints (NTI, Lucia jig) carry a risk of posterior tooth supraeruption with prolonged use
• No single splint type has been proven superior to others for TMD pain reduction, as confirmed by the 2023 systematic review (PMID: 36241594)

Lack of Clinical Consensus on Occlusal Splint Selection: A Systematic Review of the Evidence

Abstract

1. Introduction

2. Scope of the Problem

2.1 Heterogeneity of Splint Types

2.2 Diagnostic Heterogeneity in Available Trials

3. Systematic Review of Evidence by Clinical Condition

3.1 Myogenous TMD (Myalgia / Myofascial Pain)

3.2 Arthrogenous TMD (Disc Displacement with Reduction — DDwR)

• No evidence of difference between ARS and other splints for TMJ clicking in the short term (RR 1.25, 95% CI 0.91–1.72)
• A small difference favouring other splints over ARS in the long term for TMJ clicking (RR 2.40, 95% CI 1.04–5.55)
• No evidence of difference for TMJ pain or muscle pain in either short or long term
• The certainty of evidence was rated low to very low [11]

3.3 Disc Displacement without Reduction (Closed Lock) and Osteoarthritis

3.4 Mixed/Combined TMD

3.5 Sleep Bruxism (SB)

4. Sources of the Evidence Gap

4.1 Lack of Diagnostic Standardisation

4.2 Small Sample Sizes and Short Study Durations

4.3 Heterogeneity of Outcome Measures

4.4 Risk of Bias

4.5 Absence of a Universal Classification Framework

4.6 Mechanism of Action Remains Unclear

5. What Limited Evidence Does Suggest

6. Recommendations for Future Research

1. Standardised diagnosis: All future trials should use DC/TMD as the mandatory diagnostic framework to allow stratification by subdiagnosis [6].
2. Head-to-head comparative trials: High-quality RCTs directly comparing splint types within the same TMD subdiagnosis with adequate sample sizes (≥50 per arm) are urgently needed [8, 11].
3. Long-term follow-up: Studies must extend beyond 3 months to evaluate durability of outcomes and potential adverse effects (occlusal changes, condylar remodelling) [15].
4. Standardised outcome reporting: Adoption of core outcome sets (COS) for TMD trials — including pain intensity, jaw function, quality of life, and joint noise — would allow meaningful meta-analysis [7, 13].
5. Mechanistic research: Studies investigating the neurophysiological and biomechanical mechanisms of individual splint types are needed to rationalise selection [3, 16].
6. Adverse event reporting: Mandatory reporting of adverse effects (tooth movement, bite change, increased pain) is currently inconsistent and needs standardisation [12].

7. Conclusion

References

1. Schiffman E, Ohrbach R, Truelove E, Look J, Anderson G, Goulet JP, et al. Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for clinical and research applications: recommendations of the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group. J Oral Facial Pain Headache. 2014;28(1):6–27.
2. The Academy of Prosthodontics. The Glossary of Prosthodontic Terms: Ninth Edition (GPT-9). J Prosthet Dent. 2017;117(5S):e1–e105.
3. Bhargava D, Bhargava A, Mendenhall L, Mayr M, Robledo AR, Bhargava MK, et al. Recommendations on the use of oral orthotic occlusal appliance therapy for temporomandibular joint disorders: current evidence and clinical practice. J Maxillofac Oral Surg. 2023;22(4):797–807.
4. Okeson JP. Management of Temporomandibular Disorders and Occlusion. 7th ed. St Louis: Mosby Elsevier; 2013.
5. Alqutaibi AY, Aboalrejal AN. Types of occlusal splint in management of temporomandibular disorders (TMD). J Arthritis. 2015;4(4):1000161.
6. Singh BP, Singh N, Jayaraman S, Kirubakaran R, Joseph S, Muthu MS. Occlusal interventions for managing temporomandibular disorders. Cochrane Database Syst Rev. 2024;9:CD012850. [PMID: 39282765]
7. de Souza RF, Lovato da Silva CH, Nasser M, Fedorowicz Z, Al-Muharraqi MA. Interventions for the management of temporomandibular joint osteoarthritis. Cochrane Database Syst Rev. 2012;(4):CD007261. [PMID: 22513948]
8. Orzeszek S, Waliszewska-Prosol M, Ettlin D, Seweryn P, Straburzynski M, Martelletti P, et al. Efficiency of occlusal splint therapy on orofacial muscle pain reduction: a systematic review. BMC Oral Health. 2023;23(1):180. [PMID: 36978070]
9. Al-Moraissi EA, Farea R, Qasem KA, Al-Wadeai MS, Al-Sabahi ME, Al-Iryani GM. Effectiveness of occlusal splint therapy in the management of temporomandibular disorders: network meta-analysis of randomized controlled trials. Int J Oral Maxillofac Surg. 2020;49(8):1042–56. [PMID: 31982236]
10. Farrar WB. Characteristics of the condylar path in internal derangements of the TMJ. J Prosthet Dent. 1978;39(3):319–23.
11. Maheshwari K, Srinivasan R, Singh BP, Tiwari B, Kirubakaran R. Effectiveness of anterior repositioning splint versus other occlusal splints in the management of temporomandibular joint disc displacement with reduction: a meta-analysis. J Indian Prosthodont Soc. 2024;24(1):30–9. [PMID: 38263554]
12. Tyrrell HRF, Tyrrell W. Oral splints for temporomandibular disorder or bruxism: a systematic review. Br Dent J. 2021;230(9):581–6.
13. Tournavitis A, Sandris E, Theocharidou A, Slini T, Kokoti M, Koidis P. Effectiveness of conservative therapeutic modalities for temporomandibular disorders-related pain: a systematic review. Acta Odontol Scand. 2023;81(4):307–16. [PMID: 36354093]
14. Ainoosah S, Farghal AE, Alzemei MS, Saini RS, Gurumurthy V, Quadri SA. Comparative analysis of different types of occlusal splints for the management of sleep bruxism: a systematic review. BMC Oral Health. 2024;24(1):42. [PMID: 38182999]
15. Jokubauskas L, Baltrusaityte A, Pileickiene G. Oral appliances for managing sleep bruxism in adults: a systematic review from 2007 to 2017. J Oral Rehabil. 2018;45(1):59–74. [PMID: 28859236]
16. Ferreira GF, Carletti TM, Gama LT, Magno MB, Maia LC, Rodrigues Garcia RCM. Influence of occlusal appliances on the masticatory muscle function in individuals with sleep bruxism: a systematic review and meta-analysis. Eur J Oral Sci. 2024;132(2):e12979. [PMID: 38421263]
17. Melo G, Duarte J, Pauletto P, Porporatti AL, Stuginski-Barbosa J, Winocur E, et al. Bruxism: an umbrella review of systematic reviews. J Oral Rehabil. 2019;46(7):666–90. [PMID: 30993738]
18. Zhang Y, Zhang H, Liu R, Jin S, Huo T, Wei H. The efficacy of treatments for temporomandibular disorders with occlusal splints versus other conservative therapies: a meta-analysis of randomized controlled trials. Oral Surg Oral Med Oral Pathol Oral Radiol. 2025;139(5):e1–e12. [PMID: 39893122]
19. Denardin ACS, do Nascimento LP, Valesan LF, Da Cas CD, Pauletto P, Garanhani RR. Disocclusion guides in occlusal splints on temporomandibular disorders and sleep bruxism: a systematic review. Oral Surg Oral Med Oral Pathol Oral Radiol. 2023;135(1):15–27. [PMID: 36241594]
20. Chahrour M, Haddad C, Hanna P, Bejjani G, Haddad G. Assessment of using occlusal splints without other adjunctive treatment modules in the management of temporomandibular disorders: a systematic review of literature. Cureus. 2025;17(8):e89955. PMC12431960.

Fabrication Methods for Occlusal Splints: Which Technique Should Be Chosen? A Systematic Review

Abstract

1. Introduction

• Dimensional accuracy and fit — degree of polymerisation shrinkage and residual stress
• Mechanical properties — flexural strength, surface hardness, wear resistance, fracture toughness
• Surface characteristics — roughness, porosity, and susceptibility to bacterial colonisation
• Chair time — duration of intraoral adjustment required at delivery
• Laboratory time and cost
• Biocompatibility — cytotoxicity and water sorption

2. Methods

3. Overview of Fabrication Methods

3.1 Conventional Fabrication Techniques

3.1.1 Heat-Cured Polymethyl Methacrylate (HC-PMMA)

• The longstanding gold standard fabrication method
• Superior flexural strength (100–130 MPa) compared to cold-cured and 3D printed materials [4]
• Lower porosity than cold-cured (autopolymerised) acrylic due to controlled processing conditions
• Lower residual monomer content vs. cold-cured acrylic, improving biocompatibility
• Excellent polishability, long clinical track record

• Dimensional changes due to polymerisation shrinkage (typically 0.3–0.5%)
• Time-consuming laboratory process (minimum 4–5 hours)
• Susceptible to storage-related distortion in warm environments
• Requires secondary impression/remount if dimensional changes are significant

3.1.2 Cold-Cured (Autopolymerising / Self-Curing) PMMA

• Rapid fabrication — possible chairside in some protocols
• Less equipment required
• Used for provisional or short-term appliances

• Higher residual monomer content (up to 5%) compared to HC-PMMA — potential cytotoxicity risk [4, 5]
• Greater porosity and reduced flexural strength relative to HC-PMMA
• Higher water sorption and water solubility
• More susceptible to fracture and discolouration
• Not recommended for long-term splint use

3.1.3 Thermoforming / Vacuum Pressure Forming

• Rapid and low-cost fabrication (15–20 minutes laboratory time)
• Excellent initial fit and close adaptation to tooth anatomy
• Used for soft/resilient splints (2–3 mm EVA) or hard occlusal devices (3–4 mm PET-G/polycarbonate)
• No chairside adjustment typically needed
• Most accessible technique — can be performed in a basic dental office without a laboratory

• Thermoformed splints are susceptible to permanent deformation under intraoral temperature (≈37°C) and repeated occlusal loading [6]
• PET-G and EVA sheets show the highest wear of all fabrication materials [6]
• No provision for occlusal balance or cusp guidance — no flat occlusal table without additional resin
• Surface hardness lower than HC-PMMA
• Vacuum-formed splints showed highest wear in comparative studies by Grymak et al. [6]

4. Digital Fabrication Techniques

4.1 CAD-CAM Subtractive Milling

1. Intraoral digital impression (IDS) or scan of conventional stone cast (extraoral scanner)
2. Digital design using dedicated software (e.g., exocad Bite Occlusal Device Module, 3Shape)
3. CNC milling of a pre-polymerised disc or block (PMMA, PEEK, or hybrid resin)
4. Polishing and finishing

• Milled PMMA showed lower surface roughness than conventional PMMA (Hedge's g = −1.25, 95% CI −1.84 to −0.66)
• No significant difference in volume loss (wear) between milled and conventional groups (p>0.05)
• Surprisingly, flexural strength was higher in conventional (HC-PMMA) control group compared to milled (Hedge's g = 2.32, 95% CI 0.10–4.53) — an important counter-intuitive finding

• Milled PMMA splints demonstrated highest fracture resistance (mean 3,051 N)
• Conventional acrylic: 1,304 N
• 3D printed (rigid resin): 1,490 N
• Flexible thermoformed splint: 1,943 N

• All three groups showed significant improvement in TMD palpation and mandibular movement scores (p<0.001)
• PEEK and milled PMMA showed significantly less surface wear than conventional thermoformed controls (p<0.001)
• PEEK and PMMA groups also caused less antagonist tooth wear
• Fit: Control (thermoformed) group demonstrated the best initial fit (p<0.001)
• No significant difference in patient satisfaction among groups (p>0.05)
• Conclusion: "CAD-CAM materials exhibit clinically acceptable outcomes, and their performance is comparable with that of traditional materials" [9]

• Reduced polymerisation shrinkage (pre-polymerised blocks)
• Better dimensional stability than conventional methods
• Superior surface smoothness — lower roughness reduces plaque accumulation [7]
• Digital records stored — easy remakes without re-impression
• Reduced chair time for occlusal adjustment (more accurate fit from the outset)
• PEEK blocks offer exceptional wear resistance and elastic modulus (~4 GPa)

• High equipment investment (CAD-CAM unit, scanner, milling machine)
• Material disc/block cost
• Milling of PEEK requires specialised diamond tools due to material hardness
• Requires skilled operator for digital design software
• Some studies report CAD-CAM splints still require chairside occlusal equilibration [10]

4.2 Additive Manufacturing (3D Printing)

• Stereolithography (SLA): UV laser cures liquid photopolymer layer-by-layer; high resolution
• Digital Light Processing (DLP): Entire layer cured simultaneously by projected UV light; faster than SLA
• Material Jetting: Multiple materials can be deposited simultaneously; high accuracy but expensive
• Fused Deposition Modelling (FDM): Thermoplastic filament extruded; limited application for splints due to surface roughness

• 3D printed splints generally meet ISO standards for flexural strength and wear resistance
• However, their mechanical properties are 15–30% lower than heat-cured PMMA in head-to-head comparisons
  • Flexural strength: 3D printed resins 50–100 MPa vs. HC-PMMA 100–130 MPa
• Study-to-study variability is high depending on resin brand, printing orientation, and post-curing protocol
• Some resins show significantly reduced hardness and fatigue resistance

• 3D printed materials showed the highest water sorption and water solubility among fabrication groups
• Lowest degree of double bond conversion (DC%) — indicating incomplete polymerisation, potential cytotoxicity concern
• PMMA-based materials (both conventional and CAD-CAM) showed superior hardness, wear resistance, flexural strength, flexural modulus, and fracture toughness vs. 3D printed resins

• Both conventional techniques produced acceptable intraoral adaptation after chairside adjustment
• None of the 3D-printed splints seated completely on the maxillary arch, preventing accurate equilibration at delivery
• Digital workflows reduced total clinical chair time for adjustment
• Conventional methods were more reliable and consistent in initial fit
• Conclusion: "Refining digital printing protocols [is needed] before CAD-CAM printed splints can achieve consistent intraoral adaptation comparable with conventional methods" [10]

• Rapid prototyping and on-demand fabrication
• Minimal material waste
• Cost-effective once equipment is available
• High geometric customisation potential
• Enables complex designs (e.g., hollow structures, graduated hardness)
• AI-driven design integration emerging [11]

• Mechanical properties currently inferior to HC-PMMA and milled PMMA
• Post-processing complexity (washing, UV post-curing) introduces variability
• Higher water sorption — dimensional changes over time
• Resin-specific heterogeneity — results from one brand do not transfer to another
• Long-term durability and biocompatibility data remain limited
• Currently not suitable as primary long-term hard splint without further evidence [7, 11]

5. Materials Comparison

5.1 PEEK (Polyetheretherketone)

• Flexural strength: ~150–170 MPa (superior to PMMA)
• Excellent wear resistance — produces significantly less antagonist tooth wear than PMMA or thermoformed materials [9]
• High elastic modulus (~4 GPa), providing rigidity without brittleness
• Biocompatible, no leaching of residual monomers
• Radiolucent
• Chemical resistance to oral fluids

• PEEK and PMMA: comparable therapeutic efficacy (no significant difference in TMD symptom improvement)
• PEEK: significantly less surface wear and less antagonist wear than thermoformed controls
• Fit: PEEK/PMMA (CAD-CAM) showed inferior initial fit compared to thermoformed (p<0.001) — required more chairside adjustment

5.2 Thermoformed Soft Materials (EVA, PET-G, Silicone)

6. Comparison of Fabrication Methods: Summary of Evidence

6.1 Mechanical Properties

6.2 Clinical and Practical Parameters

7. Specific Clinical Recommendations by Scenario

7.1 Long-Term Hard Stabilisation Splint (Michigan/Flat-Plane Type)

• HC-PMMA has the longest evidence base and the most predictable clinical outcomes
• CAD-CAM PMMA offers superior surface smoothness, digital record-keeping, and comparable clinical outcomes with less polymerisation shrinkage [7, 9]
• PEEK via CAD-CAM is an excellent choice when maximum wear resistance is needed (severe bruxism, history of splint fracture) [9]

7.2 Short-Term Splint / Muscle Deprogrammer / Provisional Appliance

• Thermoformed appliances offer rapid, low-cost fabrication
• Acceptable for short-duration use (≤3 months); deformation and wear limit long-term viability [6, 10]
• Cold-cure PMMA is suitable for temporary chairside splints, with caution regarding residual monomer

7.3 Soft / Resilient Splint

• Only viable method for producing truly soft/resilient splints
• Silicone splints can be laboratory-processed but show higher wear
• Intended for short-term use only; evidence suggests soft splints may increase masticatory muscle EMG activity in a subset of patients [12]

7.4 Anterior Repositioning Splint (ARS)

• Precise condylar positioning requires a stable, dimensionally accurate base
• HC-PMMA base with chairside cold-cure ramp additions is the traditional method
• CAD-CAM design of ARS is feasible but requires accurate dynamic jaw registration

7.5 Resource-Limited Settings / Single-Visit Fabrication

• Accessible without laboratory investment
• Accepted clinical compromise when full conventional fabrication is not available

8. Discussion

8.1 The Role of Intraoral Scanning

8.2 Gaps in Evidence

1. Long-term clinical RCTs (>12 months) comparing fabrication methods head-to-head for therapeutic outcomes are absent
2. Biocompatibility data (cytotoxicity, water sorption effects, mucosal response) for 3D printed resins over extended wear periods remain limited [7]
3. Cost-effectiveness analyses comparing fabrication workflows are lacking
4. Standardised protocols for 3D printing orientation, post-curing time/intensity, and polishing for splint resins are not yet established [11]
5. PEEK-based splints, while mechanically superior, lack long-term clinical trials and post-market surveillance data for this specific indication [9]

9. Conclusion

• Heat-cured PMMA (conventional heat-processing) remains the most evidence-supported fabrication method for long-term hard occlusal stabilisation splints, given its superior mechanical properties, long clinical track record, low residual monomer, and excellent polishability.
• CAD-CAM milled PMMA is a strong, evidence-supported alternative offering reduced surface roughness, digital record storage, reduced polymerisation shrinkage, and comparable therapeutic efficacy. It is recommended where digital infrastructure is available.
• CAD-CAM milled PEEK offers best-in-class wear resistance and is indicated for patients with severe bruxism, high occlusal forces, or history of splint fracture, with the caveat of higher cost.
• Thermoforming is appropriate for soft/resilient splints, short-term deprogrammers, and resource-limited settings — not for long-term hard stabilisation.
• 3D printed splints are promising but currently show inferior mechanical properties (15–30% lower flexural strength than HC-PMMA), higher water sorption, inconsistent intraoral fit, and limited long-term clinical data. They are currently best reserved for short-term provisional appliances or as an adjunct to other methods.
• Cold-cured PMMA is a chairside-viable option for temporary or short-duration appliances only, due to higher residual monomer and lower mechanical properties.

References (Vancouver Style)

1. The Academy of Prosthodontics. The Glossary of Prosthodontic Terms: Ninth Edition (GPT-9). J Prosthet Dent. 2017;117(5S):e1–e105.
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4. Berli C, Thieringer FM, Sharma N, Müller JA, Msallem B, Fischer J, et al. Comparing the mechanical properties of pressed, milled, and 3D-printed resins for occlusal devices. J Prosthet Dent. 2020;124(6):780–6.
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8. Abad-Coronel C, Ruano Espinosa C, Ordóñez Palacios S, Paltán CA, Fajardo JI. Comparative analysis between conventional acrylic, CAD/CAM milled, and 3D CAD/CAM printed occlusal splints. Materials (Basel). 2023;16(18):6269.
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Awareness Amongst Dentists in Choosing Fabrication Technique for Occlusal Splints: Conventional, CAD-CAM Milled, and 3D Printed — A Systematic Review

Abstract

1. Introduction

1. Conventional fabrication — encompasses heat-cured polymethyl methacrylate (HC-PMMA), cold-cured (autopolymerising) PMMA, and vacuum/thermoforming with thermoplastic sheets
2. CAD-CAM subtractive milling — computer-aided design and manufacturing by CNC milling from pre-polymerised PMMA, PEEK (polyetheretherketone), or hybrid resin discs/blocks
3. Additive manufacturing (3D printing) — layer-by-layer photopolymer deposition using stereolithography (SLA), digital light processing (DLP), or material jetting technologies

2. Methods

• Studies reporting data on dentist/dental professional knowledge, awareness, attitudes, or practice patterns related to digital or conventional occlusal splint/dental appliance fabrication
• Survey-based, cross-sectional, observational, or experimental studies with quantitative outcomes
• Studies published in English (or with English abstracts)
• Studies that indirectly characterise the knowledge base required for informed fabrication selection (i.e., comparative technical studies assessing mechanical and clinical properties of the three fabrication methods)

• Animal studies or case reports
• Studies exclusively addressing implant prosthetics, fixed prosthetics, or orthodontic appliances without applicability to splint fabrication
• Studies with no quantitative outcomes

3. Results

3.1 Dentist Awareness of TMD and Occlusal Splint Therapy

• Only 58.1% of general dentists were confident in managing TMD patients
• Only 46.8% of specialists were confident — a counterintuitive finding indicating training gaps even among advanced practitioners
• Splint therapy was the preferred management modality for general dentists, yet only surface-level fabrication knowledge was documented
• Conclusion: "Indian dentists lack sufficient training in dental schools on all three sections" [10]

• 77.7% reported receiving TMD patients frequently
• The majority managed TMD patients with occlusal splints as the primary intervention
• However, the survey did not assess which fabrication method dentists selected, or whether they possessed criteria for technique selection — highlighting a critical absence of fabrication-specific awareness data in the broader TMD management literature [11]

• Interocclusal appliances (splints) were the treatment with which the highest proportion of GPDs felt confident and reported good clinical routines
• However, confidence in TMD diagnostics and therapy decisions was significantly lower than confidence in splint prescribing
• A majority of GPDs expressed desire for continuing education from TMD/orofacial pain specialists
• Critically, the survey did not distinguish between fabrication methods, reflecting the period when digital options were not yet widely available — but establishing the pattern of comfort with splint prescription alongside lack of deeper technical understanding [12]

• 88.2% of dental practitioners reported managing TMD/OFP patients with bite splints/occlusal guards — the highest-used intervention
• Yet significant diversity existed in management approaches, and no data were collected on fabrication awareness
• Conclusion: "The study enables the identification of gaps in knowledge and management approaches" [13]

3.2 Dentist Awareness of Digital Fabrication Technologies

3.2.1 3D Printing Awareness

• 75% of dentists had never used a 3D printer in their clinical practice
• Only 12% used 3D printers several times per month; 8% several times per week; 4% daily
• Dentists with ≤5 years of experience demonstrated significantly higher knowledge of 3D printing than those with more experience (p<0.05)
• The primary limiting factor was identified as high equipment cost
• Conclusion: "Primary obstacles include equipment cost, lack of structured practical education, and uncertainty about workflow integration" [14]

3.2.2 CAD-CAM and Digital Workflow Adoption

• Among dentists, 76% used digital tools overall (χ² = 10.00, p = 0.002)
• Intraoral scanner usage was high (90.3% of dentists; χ² = 25.60, p < 0.001)
• Design software usage: 83.3% of dentists (χ² = 16.90, p < 0.001)
• But milling and 3D printing were significantly underutilised — primary reasons: cost (61.5%) and limited in-house expertise
• 43.3% of dentists had received no predoctoral digital dentistry training
• Private clinics had significantly higher digital adoption (73.3%) vs. public clinics (53.3% reporting no adoption; χ² = 12.91, p < 0.001)
• Dental technicians showed substantially higher 3D printing adoption (LCD printer usage: 78%; χ² = 25.36, p < 0.001) than dentists — suggesting that fabrication decisions are often delegated to the laboratory without the prescribing dentist possessing informed selection criteria [6]

3.2.3 Awareness in India

• Digital radiography showed the highest adoption — familiar to most dentists
• Advanced digital tools (intraoral scanners, 3D printing) had significantly lower awareness and usage
• Overall awareness was rated as moderate
• Adoption was constrained by: cost, integration issues, and data security concerns
• The study specifically noted gaps in practical understanding of advanced digital tools
• Conclusion: "The need for enhanced training in CBCT and oral radiology [and other digital technologies]" was emphasised [7]

3.2.4 Dental School Integration

• CAD-CAM complete dentures were taught didactically in 54.2% of predoctoral programs and 65.2% of advanced programs
• CAD-CAM removable partial dentures were taught in only 37.5% of predoctoral programs — and data on CAD-CAM splint fabrication teaching were even less frequently reported
• Programs were limited by lack of funds, resources, time, and qualified faculty
• Conclusion: "While digital technologies have become more prevalent in dental education, many institutions face barriers to implementation" [15]

3.2.5 German Dentists

• Expected increase in digital technology impact anticipated across all technologies by 2030
• Age and clinic size were major factors influencing technology uptake — older dentists and smaller practices showed lower adoption
• A gap in digital technology education within current dental training was identified
• No significant gender-related differences in adoption [16]

3.3 Specific Awareness Regarding Occlusal Splint Fabrication

3.3.1 Educational Exposure to Splint Fabrication

• Clinicians demonstrated significantly higher mastery than students in both theoretical (p = 0.001) and practical training (p < 0.001)
• Both groups found fabrication technically challenging — students more so for foundational steps ("resin laying, framework fabrication, and occlusal surface shaping"; p = 0.012)
• Clinicians prioritised foundational occlusal knowledge as most critical; students prioritised meticulous adjustment — a difference reflecting how theoretical understanding evolves with experience
• Self-rated splint comfort: clinicians rated fabricated splints as comfortable significantly more often than students (p < 0.001)
• Critically: the course taught only conventional fabrication — no digital workflow components were included — illustrating how dental education continues to default to conventional technique even in 2026 [17]

3.3.2 Technology Delegation Pattern

• Dentists who lack fabrication knowledge cannot specify the optimal technique
• Laboratory adoption of digital tools does not translate to dentist awareness of technique implications
• Clinical outcomes may be influenced by fabrication decisions in which the clinician had no informed role

3.4 Barriers to Informed Fabrication Technique Selection

3.5 What Dentists Need to Know: The Evidence Base for Informed Selection

Therapeutic Equivalence

Mechanical Superiority of Milled PMMA

3D Printing Limitations

3.6 Regional Patterns of Awareness

4. Discussion

4.1 The Double Gap: TMD Knowledge + Fabrication Literacy

4.2 The Delegation Problem

• Patients with severe bruxism (who may benefit from PEEK or milled PMMA for superior wear resistance) may receive thermoformed or cold-cured appliances by default
• Patients in practices with access to intraoral scanners may benefit from fully digital workflows (faster delivery, digital record storage) but receive conventional appliances because the dentist did not request a digital pathway
• Cost-sensitive patients who could benefit from a thermoformed EVA splint for short-term use may receive more expensive milled devices unnecessarily

4.3 The Generational Inversion

4.4 Educational Interventions Required

• Didactic teaching on all three fabrication methods
• Hands-on preclinical and clinical training with digital workflows
• Decision-making frameworks based on patient clinical characteristics

4.5 Limitations of the Evidence

• Most surveys have regional focus (India, Jordan, Turkey, Sweden) with limited generalisability
• Self-reported surveys are subject to social desirability bias — actual knowledge may be lower than reported
• Rapidly evolving technology means survey data from 2016–2022 may not reflect the current awareness landscape

5. Conclusion

1. Dentists globally have moderate-to-low awareness of digital fabrication techniques (CAD-CAM milling, 3D printing) for occlusal splints, with the majority defaulting to conventional fabrication by habit, training, or lack of awareness of alternatives.
2. The primary barriers to informed fabrication technique selection are: high equipment cost, inadequate predoctoral training, lack of structured continuing education, the generational gap in digital literacy, and over-reliance on laboratory delegation.
3. Younger dentists (<5 years' experience) demonstrate consistently higher digital technology knowledge, reflecting improved contemporary curricula but creating a paradox in clinical settings where senior practitioners control decisions.
4. No existing survey directly and comprehensively evaluates dentists' ability to make evidence-based occlusal splint fabrication selections — representing a critical research gap that original questionnaire-based studies should address.
5. Emerging evidence (comparative RCTs, systematic reviews) supports the clinical equivalence of well-fabricated digital and conventional splints for therapeutic outcomes, which, once widely disseminated, may reduce the clinician's perceived risk in adopting digital workflows.
6. A structured, evidence-based decision framework — incorporating patient clinical needs, practice resources, fabrication evidence, and cost considerations — is urgently needed to standardise splint fabrication decision-making in clinical practice.

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