Temporomandibular Disorders in India: Prevalence, Burden, and Treatment with Full-Mouth Rehabilitation, Dental Implants, and Occlusal Splints

A Thesis Write-Up with References and Citations

1. Introduction

2. Global Epidemiology of TMDs

• Myalgia to be the most prevalent subtype (37.2%), followed by clicking/joint sounds (29.8%) and arthralgia (16.8%)
• Female predilection: Women were affected at a rate of 36.7% versus 26.7% in men, representing a 1.75-fold greater likelihood in females
• Age pattern: Subjects under 18 years showed a prevalence of 38.5%, comparable to adults (34.1%)
• Continental variation: Asia demonstrated a TMD prevalence of 27.9%, lower than Europe (33.8%) but higher than North America (19.4%)

3. Prevalence and Burden of TMDs in India

3.1 Epidemiological Data from Indian Studies

• Overall prevalence of TMJ pain: 10.5%
• Difficulty in jaw opening: 11.2%
• TMJ sounds: 14%
• Bruxism: 17%
• TMD symptoms were more prevalent in females than males
• Bruxism carried the highest odds ratio (OR = 8 for age 60–70 years; OR = 15.1 for 70–80 years) for TMD association

3.2 Gaps in Indian National Data

4. Full-Mouth Rehabilitation in TMD: Rationale and Scope

4.1 Pathophysiological Basis

4.2 Treatment Protocol

1. Diagnostic phase: DC/TMD-based examination, CBCT/MRI of the TMJ, facebow transfer, and articulator-mounted diagnostic casts
2. Phase I (occlusal splint therapy): Stabilization splint worn for 3–6 months to establish a reproducible, muscle-relaxed centric relation and confirm VDO
3. Phase II (provisional restorations): Full-arch provisionals to test and refine the new occlusal scheme
4. Phase III (definitive restorations): Combination of fixed prostheses, implant-supported crowns/bridges, and removable partial dentures based on the missing tooth map

5. Occlusal Splints in TMD Management

5.1 Mechanism of Action

• Disengaging proprioceptive occlusal feedback, reducing masticatory muscle hyperactivity
• Allowing the mandible to seat in a physiological centric relation
• Providing a reversible "test" occlusion before irreversible restorative intervention
• Protecting teeth and restorations from bruxism-induced wear

5.2 Evidence for Efficacy

• Full hard stabilization splint (FHSS) may reduce muscle pain when chewing compared to no treatment (MD −1.97, 95% CI −2.37 to −1.57; 1 study, 84 participants)
• Overall certainty of evidence was very low for all comparisons due to study heterogeneity and risk of bias
• The review calls for standardized, large RCTs with DC/TMD-based enrollment to resolve current uncertainty

• Occlusal splints had a positive effect on mandibular movements in all 11 included studies
• Seven studies demonstrated significant chronic pain reduction and reduced pain intensity
• Improvements in mouth opening, depression, and anxiety were reported in 4 studies
• Male-to-female ratio was 0–25%, reinforcing the female-predominant demographic

5.3 Splint Use in the Indian Context

6. Dental Implants in TMD Patients

6.1 Indications

• Structural: Restoring posterior support and distributing occlusal forces away from the TMJ
• Functional: Re-establishing a stable occlusal stop that forms the cornerstone of any FMR plan

6.2 Special Considerations in TMD Patients

• Bruxism management is mandatory prior to implant loading, as parafunctional forces can exceed 600–900 N and jeopardize osseointegration
• VDO correction must be confirmed before implant-level impressions, to avoid fabricating implant prostheses at an incorrect occlusal vertical dimension
• Occlusal splint therapy precedes implant placement in patients with active myofascial pain to establish muscular equilibrium
• CBCT-guided implant placement ensures adequate bone volume, particularly in long-edentulous cases with bone atrophy

6.3 Evidence

7. Integrated Treatment Model: A Proposed Protocol for Indian Patients

8. Summary and Key Observations for Thesis

1. TMDs affect approximately 27.9% of the Asian population (Alqutaibi et al., 2025), translating to an estimated 265+ million Indians with TMD signs or symptoms — one of the largest disease burdens globally, yet minimally studied in an Indian-specific large-scale context.
2. Indian epidemiological data (Prakash et al., 2022; Shetty et al., 2025) confirm TMD symptom prevalence in 10–17% of elderly and clinical populations studied, with female predominance and strong association with bruxism and postural deviations.
3. Occlusal splints remain the first-line, evidence-based intervention for TMD (Singh et al., 2024; Zhang et al., 2020), though evidence certainty remains low due to study heterogeneity.
4. Full-mouth rehabilitation with dental implants is indicated in the subgroup of TMD patients with advanced occlusal breakdown, and must be preceded by splint therapy to establish neuromuscular equilibrium.
5. A critical gap exists: India has no national registry or systematic tracking of TMD treatment outcomes, including splint prescriptions, implant placements for TMD-related edentulism, or FMR case loads. This thesis recommends the establishment of a national TMD registry as a public oral health priority.

References

1. Alqutaibi AY, Alhammadi MS, Hamadallah HH, Altarjami AA, Malosh OT, Aloufi AM. Global prevalence of temporomandibular disorders: a systematic review and meta-analysis. J Oral Facial Pain Headache. 2025;Jun. doi:10.22514/jofph.2025.025. PMID: 41070533.
2. Bueno CH, Pereira DD, Pattussi MP, Grossi PK, Grossi ML. Gender differences in temporomandibular disorders in adult populational studies: A systematic review and meta-analysis. J Oral Rehabil. 2018;45(9):720–729. doi:10.1111/joor.12661. PMID: 29851110.
3. Minervini G, Franco R, Marrapodi MM, Fiorillo L, Cervino G, Cicciù M. Economic inequalities and temporomandibular disorders: A systematic review with meta-analysis. J Oral Rehabil. 2023;50(8):765–773. doi:10.1111/joor.13491. PMID: 37162279.
4. Prakash J, Kumar R, Devi LS, Shenoy M, Abdul NS, Shivakumar GC. Assessment of symptoms associated with temporomandibular dysfunction and bruxism among elderly population: An epidemiological survey. J Contemp Dent Pract. 2022;23(4):397–402. PMID: 35945831.
5. Shetty SK, Katageri AI, Shetty R, Ragher M, Prabhu UM. Evaluation of the effect of temporomandibular joint disorders on craniocervical posture: A cross-sectional study. J Indian Prosthodont Soc. 2025;Oct 1. doi:10.4103/jips.jips_273_25. PMID: 41111218.
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. doi:10.1002/14651858.CD012850.pub2. PMID: 39282765.
7. Zhang SH, He KX, Lin CJ, Liu XD, Wu L, Chen J. Efficacy of occlusal splints in the treatment of temporomandibular disorders: a systematic review of randomized controlled trials. Acta Odontol Scand. 2020;78(8):559–567. doi:10.1080/00016357.2020.1759818. PMID: 32421379.
8. Ahmad SA, Hasan S, Saeed S. Low-level laser therapy in temporomandibular joint disorders: a systematic review. J Med Life. 2021;14(2):148–164. PMID: 34104237.
9. Okeson JP. Management of Temporomandibular Disorders and Occlusion. 8th ed. St. Louis: Elsevier; 2019.
10. Schiffman E, Ohrbach R, Truelove E, 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. PMID: 24482784.

Important Caveat for Your Thesis

There is no published national-level data specifically quantifying the number of Indian patients with TMD receiving full-mouth rehabilitation, dental implants, or occlusal splints as a combined treatment modality. This is a documented evidence gap. Your thesis should acknowledge this explicitly, frame it as a research gap justifying your study, and use the available regional, institutional, and global extrapolation data as described above to contextualize the burden. Recommending a national TMD registry is a strong and original policy recommendation that strengthens any thesis in this area.

Occlusal Splints in Temporomandibular Disorders: Types, Duration of Wear, and Evidence-Based Guidelines

1. Introduction

• Disengaging tooth proprioceptive signals that drive masticatory muscle hyperactivity
• Allowing the mandibular condyle to seat in a reproducible, muscle-relaxed centric relation (CR)
• Protecting enamel and restorations from bruxism-induced attrition
• Redistributing occlusal forces across the arch and away from the TMJ
• Providing a reversible test for a new vertical dimension of occlusion (VDO) before definitive prosthetic reconstruction

2. Classification of Occlusal Splints

2.1 Stabilization Splint (Michigan Splint / Centric Relation Splint / Full Hard Stabilization Splint – FHSS)

Description

Design Characteristics

• Material: Hard heat-cured or pressure-formed acrylic resin (2–3 mm thickness)
• Coverage: Full arch — covers all maxillary (or mandibular) teeth
• Occlusal contacts: Bilateral, simultaneous, even occlusal contacts on the flat occlusal plane; anterior guidance provided by canine rise during lateral excursions; mutually protected occlusion
• Position: Mandible guided to centric relation (CR), the most orthopedically stable joint position
• No tooth movement: Purely reversible

Mechanism of Action

• Provides a flat, stable occlusal platform that eliminates tooth-guided excentric movements
• Disengages posterior tooth contact in excursions, reducing lateral pterygoid and masseter hyperactivity
• Allows the condyle to seat in the glenoid fossa in a bilaterally simultaneous, strain-free position
• Reduces EMG activity of masticatory muscles by 30–60% (Okeson, 2019)

Indications

• Myofascial pain (masticatory muscle disorders) — primary indication
• Bruxism (nocturnal and diurnal)
• Disc displacement (as a precursor before repositioning)
• Preparatory phase before full-mouth rehabilitation (FMR)
• Diagnosis of the jaw's CR position prior to irreversible prosthodontic work
• Post-orthodontic retention in patients with TMD risk

Duration of Wear

• Short-term: 3–6 months minimum for myofascial pain (Singh et al., 2024)
• Long-term maintenance: May be used indefinitely as a night guard for bruxism protection, since no adverse occlusal changes occur with a properly adjusted FHSS
• The ElMohandes Protocol (El-Mohandes et al., 2025; PMID: 40837932) recommends wearing 10–12 hours/day over 6 months with a structured "weaning in" and "weaning out" phase, showing VAS pain reduction from 7.57 to 3.38 (p < 0.001) and mouth opening improvement from 31.87 mm to 35.61 mm
• The Cochrane review (Singh et al., 2024) reports study durations ranging from 5 weeks to 84 months, with primary outcomes assessed between 4.4 weeks and 4 months

Evidence

• The stabilization splint (FHSS) was the appliance evaluated in the majority of the 57 RCTs in the Singh et al. (2024) Cochrane review
• Zhang et al. (2020) confirmed positive effects in 11 RCTs across mandibular movement, pain intensity, and depression/anxiety outcomes
• Chafii et al. (2026; PMID: 41646618) in a prospective study (n = 70) reported a 95.5% recovery rate in the splint group versus 65.4% in the physiotherapy group (p = 0.001), with superior long-term outcomes

2.2 Anterior Repositioning Splint (ARS / Mandibular Repositioning Appliance)

Description

Design Characteristics

• Material: Hard acrylic, full arch or partial coverage (anterior ramp)
• Coverage: Full mandibular arch with an anterior inclined ramp that guides the mandible forward on closure
• Occlusal contacts: Bilateral contact at a protruded (anterior) mandibular position where clicking is eliminated
• Position: Mandible held in a protruded position (typically 2–5 mm anterior to CR)

Mechanism of Action

• On ARS insertion: condyle moves forward and downward, disc moves backward and upward, achieving normal disc-condyle relationship in 100% of treated TMJs
• However, at 6-month follow-up (without ARS): only 40.6% of joints maintained the corrected disc-condyle relationship, with most condyles returning to pre-treatment positions
• This confirms the good short-term clinical efficacy of ARS and explains its relatively lower long-term durability — an important clinical caveat

Indications

• Anterior disc displacement with reduction (clicking TMJ)
• Painful TMJ internal derangement with joint noise
• Initial reduction of joint loading before prosthetic phase

Duration of Wear

• 4 months wearing approximately 20 hours/day as used by Pihut et al. (2018; PMID: 29682131) — demonstrated significantly lower pain (VNRS) in ARS group vs laser therapy control (p = 0.0004)
• After pain resolution, the appliance is typically transitioned to a stabilization splint to avoid permanent mandibular repositioning and associated posterior open bite
• Maximum recommended duration: 3–6 months, followed by re-evaluation and transition
• Critical warning: Prolonged unrestricted use beyond 6 months WITHOUT transition can cause posterior open bite and permanent alterations in vertical dimension — the most feared complication of ARS misuse (Okeson, 2019)

Evidence

• Pihut et al. (2018; PMID: 29682131) — 112 patients (RCT): ARS for 4 months (20 hrs/day) produced significantly superior pain reduction compared to laser therapy
• Chen et al. (2017; PMID: 28600884) — 22 subjects, MRI analysis: 100% short-term disc recapture; 40.6% long-term maintenance
• Liu et al. (2017; PMID: 29069145) — Metrical analysis confirming different splint positions produce variable disc-condyle relationships, supporting position-specific splint fabrication

2.3 Soft Resilient Splint (Soft Splint / Relaxation Splint)

Description

Design Characteristics

• Material: Soft thermoplastic polyvinyl acetate-polyethylene (EVA) or polyurethane, 2–4 mm thickness
• Coverage: Full arch, either arch
• Occlusal contacts: Cusps indent into the soft material — contact is diffuse and non-specific
• No flat occlusal plane; no defined centric relation contacts

Mechanism of Action

• Provides a cushioning effect that absorbs impact forces during bruxism
• Interocclusal separation reduces mechanical loading on the TMJ
• May act as a placebo in many clinical scenarios due to lack of defined occlusal scheme

Indications

• Mild bruxism without significant TMD signs
• Tooth wear protection in low-risk patients
• Short-term pain relief
• Patients unable to afford or tolerate hard acrylic fabrication

Duration of Wear

• Generally used as a nighttime appliance only (8–10 hours during sleep)
• Short-term use: 1–3 months for acute pain relief
• Not recommended for long-term TMD management or as a pre-prosthetic splint, because:
  • Soft material does not provide stable CR contact
  • May increase masticatory muscle activity in some patients by acting as a chewing stimulus (Okeson, 2019)
  • Cannot accurately reproduce centric relation for diagnostic or prosthetic planning

Comparative Evidence

2.4 Anterior Bite Plane Splint (Anterior Deprogrammer / Lucia Jig / B-Splint)

Description

Design Characteristics

• Coverage: Anterior teeth only (typically 4–6 teeth)
• Material: Hard acrylic
• Posterior teeth: Have no occlusal contact while the device is in place — a critical design feature
• Contact: Single anterior stop, often a flat ramp

Mechanism of Action

• Proprioceptive deafferentation of posterior teeth eliminates tooth-guided deflective contacts that shift the condyle from CR
• The absence of posterior contact allows condylar seating in the most superior, anterior position of the fossa (true CR) within minutes to hours
• Used primarily as a diagnostic tool or short-term preparatory appliance, not long-term therapy

Indications

• Determination of centric relation before occlusal equilibration or FMR
• Short-term muscle deprogramming (hours to days)
• Diagnosing CO-CR discrepancy

Duration of Wear

• Maximum: 20–30 minutes per session for CR determination purposes (Lucia jig)
• As a short-term appliance: up to 2–4 weeks
• NOT recommended for overnight or extended wear: posterior open bite can develop from tooth extrusion into the opened posterior spaces within weeks of unmonitored use
• The B-splint/anterior bite plane can be worn nightly for 6–8 weeks as part of muscle deprogramming, followed by transition to full-coverage stabilization splint

Evidence

2.5 NTI-tss (Nociceptive Trigeminal Inhibition Tension Suppression System)

Description

Design Characteristics

• Coverage: Maxillary central incisors only (very small footprint)
• Material: Hard acrylic
• Contact: Single contact point for lower incisors — prevents posterior tooth contact and masseter/temporalis contraction above ~20% of maximum

Mechanism of Action

• By contacting only the mandibular incisor edge, the NTI-tss inhibits trigeminal nerve activation, suppressing the masseteric muscle contraction reflex
• Claimed to reduce masseter muscle activity by up to 68% (Shankland, 2004)
• Reduces morning headache from nocturnal bruxism

Indications

• Bruxism-associated headache and myofascial pain
• Tension-type headache
• Short-term adjunct in TMD with predominant muscle pain component

Duration of Wear

• Nighttime wear only during the active treatment phase
• Typically used for 3–6 months as a therapeutic trial
• NOT recommended for long-term unsupervised use due to risks of:
  • Anterior tooth extrusion (supraeruption of molars)
  • Posterior open bite
  • Risk of aspiration in elderly patients (small device)

Evidence Caution

2.6 Posterior Bite Plane / Pivoting Splint

Description

Design Characteristics

• Contacts only on posterior teeth bilaterally
• Anterior teeth are in open bite
• Creates a fulcrum effect that distracts the condyle inferiorly from the glenoid fossa

Indications

• TMJ inflammatory conditions (synovitis, retrodiscitis) where condylar distraction is beneficial
• Selected cases of osteoarthritis with condylar compression pain

Duration of Wear

• Very limited: 2–4 weeks for acute inflammatory phases
• Not suitable for long-term use due to anterior open bite risk and limited evidence base

2.7 Mandibular Advancement Device (MAD) / Mandibular Repositioning Appliance for OSA

Description

Duration of Wear

• Nightly, long-term use (years to indefinite) when prescribed for OSA
• Annual review for occlusal changes recommended as long-term mandibular advancement can cause posterior open bite and anterior crossbite (shift of occlusion)
• For TMD purposes specifically, used short-term (3–6 months) with re-evaluation

3. Duration of Splint Wear: A Comprehensive Summary

Key Principles Governing Duration

1. Splint therapy is not indefinitely curative. It is a reversible, temporizing, or preparatory intervention. The underlying occlusal or structural pathology must be addressed through definitive means (occlusal equilibration, prosthodontic rehabilitation, orthodontics, or surgery).
2. Re-evaluation at 4–6 weeks is mandatory to assess pain response, confirm CR reproducibility, and adjust the splint. Absence of improvement at 3 months should prompt reassessment of the diagnosis.
3. Transition from ARS to FHSS is mandatory at 3–6 months to prevent permanent positional changes.
4. Indefinite nightguard use with a well-adjusted FHSS is safe and appropriate for bruxism protection, particularly in patients with reconstructed dentitions, implants, or veneers.
5. The ElMohandes Protocol (2025; PMID: 40837932) supports a graduated wear schedule — not full-time use — combining 10–12 hours/day with physiotherapy and patient education, achieving significant VAS reduction (p < 0.001) without any occlusal adverse events over 6 months.
6. Cochrane evidence (Singh et al., 2024): Study durations in included RCTs ranged from 5 weeks to 84 months (7 years), indicating that long-term splint use is both practiced and clinically investigated — but must be monitored.

4. Contraindications and Complications of Prolonged Splint Use

5. Monitoring Protocol During Splint Therapy

• Week 1: Confirm seating, check for sharp edges, verify bilateral occlusal contact
• Week 4–6: First clinical review — assess pain (VAS/NRS), mouth opening, joint sounds, occlusal changes
• Month 3: Major milestone review — CR reproducibility, decision on continuation or transition
• Month 6: Final assessment for primary therapy; decision on definitive prosthodontic intervention or discharge to maintenance

6. Conclusion

References

1. 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. doi:10.1002/14651858.CD012850.pub2. PMID: 39282765.
2. Zhang SH, He KX, Lin CJ, Liu XD, Wu L, Chen J. Efficacy of occlusal splints in the treatment of temporomandibular disorders: a systematic review of randomized controlled trials. Acta Odontol Scand. 2020;78(8):559–567. doi:10.1080/00016357.2020.1759818. PMID: 32421379.
3. El-Mohandes WA, Elariby MS, Bahaa A. Optimizing occlusal splint therapy: ElMohandes Protocol for minimizing musculoskeletal alterations with reduced wear time. Cureus. 2025;Jul. doi:10.7759/cureus.88370. PMID: 40837932.
4. Pihut M, Gorecka M, Ceranowicz P, Wieckiewicz M. The efficiency of anterior repositioning splints in the management of pain related to temporomandibular joint disc displacement with reduction. Pain Res Manag. 2018;2018:9089286. doi:10.1155/2018/9089286. PMID: 29682131.
5. Chen HM, Liu MQ, Yap AUJ, Fu KY. Physiological effects of anterior repositioning splint on temporomandibular joint disc displacement: a quantitative analysis. J Oral Rehabil. 2017;44(9):664–672. doi:10.1111/joor.12532. PMID: 28600884.
6. Liu MQ, Lei J, Han JH, et al. Metrical analysis of disc-condyle relation with different splint treatment positions in patients with TMJ disc displacement. J Appl Oral Sci. 2017;25(5):483–489. PMID: 29069145.
7. Chafii A, El Bassity I, Ben El Hammi N, et al. The effectiveness of occlusal splint therapy vs physiotherapy in the management of temporomandibular disorders: a prospective comparative study. Cureus. 2026;Jan. doi:10.7759/cureus.100851. PMID: 41646618.
8. Conti PC, Corrêa AS, Lauris JR, et al. Management of painful temporomandibular joint clicking with different intraoral devices and counseling: a controlled study. J Appl Oral Sci. 2015;23(5):529–535. PMID: 26200526.
9. Okeson JP. Management of Temporomandibular Disorders and Occlusion. 8th ed. St. Louis: Elsevier; 2019.
10. Ramfjord SP, Ash MM. Occlusion. 3rd ed. Philadelphia: WB Saunders; 1983.
11. Schiffman E, Ohrbach R, Truelove E, et al. Diagnostic criteria for temporomandibular disorders (DC/TMD) for clinical and research applications. J Oral Facial Pain Headache. 2014;28(1):6–27. PMID: 24482784.

For your thesis: This write-up covers all clinically recognized splint types with their mechanisms, indications, evidence levels, recommended wear durations, and transition protocols. You may use individual sections as chapters or subsections. If you need a specific section formatted as an introduction, review of literature, or discussion chapter, or need APA/Vancouver citation reformatting, let me know.

Impact of Fabrication Technique on Occlusal Splints: Conventional Heat-Cured, CAD/CAM Milled, and SLA 3D-Printed — A Comparative Analysis

1. Introduction

1. Conventional heat-cured PMMA — the traditional gold standard
2. CAD/CAM subtractive milling — a digital-subtractive method
3. SLA (Stereolithography) 3D printing — a digital-additive method

2. Conventional Heat-Cured PMMA Splint

2.1 Fabrication Workflow

2.2 Material

• Polymethylmethacrylate (PMMA), heat-polymerized
• Cross-linked acrylic resin — most studied dental material
• ISO 20795-1 compliant for denture base polymers

2.3 Mechanical Properties

2.4 Advantages

• Proven clinical track record spanning 60+ years
• Highest absolute flexural strength (100–130 MPa) — suitable for severe bruxism
• Low material cost; equipment widely available in dental labs
• Repairability: chairside or lab relining and repairs are straightforward
• Familiar to all dental technicians; no digital infrastructure required

2.5 Disadvantages

• Labour-intensive: requires multiple clinical appointments (impressions, try-in, delivery, adjustment)
• Longer turnaround time: 3–7 working days for lab fabrication
• Dimensional inaccuracy from polymerization shrinkage: PMMA undergoes volumetric shrinkage of ~7% during heat processing, causing internal fit discrepancies
• Flask distortion: plaster investing and deflasking introduce dimensional errors
• Porosity: salt-and-pepper mixing technique can trap air, creating surface and internal porosity — a site for bacterial accumulation and reduced strength
• Residual monomer: poorly mixed or under-cured batches contain residual MMA monomer which is cytotoxic and may cause mucosal sensitivity
• Manual trimming variability: final surface and thickness depend heavily on technician skill
• Not ideal for digital integration: cannot be designed or modified digitally after fabrication

3. CAD/CAM Subtractive Milling (Milled PMMA Splint)

3.1 Fabrication Workflow

3.2 Material

• Pre-polymerized PMMA CAD/CAM discs (e.g., Candulor PhysioStar, Vita CAD-Temp, Ivocryl CAD)
• Industrially polymerized under high pressure and temperature — far more homogeneous than hand-mixed PMMA
• Near-zero residual monomer
• Predictable, standardized mechanical properties batch-to-batch

3.3 Mechanical Properties and Accuracy

• Milled PMMA discs demonstrate higher density and lower porosity than hand-mixed PMMA because they are factory-polymerized under controlled conditions
• Highest dimensional accuracy among all three techniques:
  • Mean RMS deviation: 0.11 ± 0.02 mm (Lee et al., 2025; PMID: 39260569) — significantly better than SLA (0.16 ± 0.02 mm) and DLP (0.14 ± 0.02 mm)
  • Post-hoc analysis confirmed milled splints had statistically superior accuracy (p < 0.01) over 3D-printed variants
• Surface roughness: milled PMMA has smooth, well-adapted surfaces after polishing, comparable or superior to heat-cured PMMA
• Flexural strength approaches or exceeds heat-cured PMMA due to industrial pre-polymerization

3.4 Impact on Clinical Fit

• Scan accuracy: IOS scan quality (especially in posterior regions)
• Virtual articulation: accuracy of jaw registration
• Mill type: 5-axis mills produce superior fit to 3-axis
• Bur wear: worn milling burs increase surface roughness and reduce accuracy

3.5 Advantages

• Highest dimensional accuracy (lowest RMS deviation) among the three techniques
• Industrially polymerized PMMA: superior mechanical properties, near-zero porosity, no residual monomer
• Fully digital workflow: no physical impressions if using IOS; reproducible, archivable, remotely modifiable
• Faster chairside time: fewer adjustments needed due to digital precision
• Batch consistency: standardized material properties every time
• Chairside or lab-based: available on tabletop mills (Roland DWX-4W, Ceramill Motion) or large lab mills
• Integration with full-mouth digital rehabilitation planning — same digital models used for splint, provisionals, and definitive restorations

3.6 Disadvantages

• High equipment cost: 5-axis milling unit + IOS = significant capital investment (₹20–50 lakh range)
• Material waste: subtractive process discards 70–80% of the PMMA puck as swarf — not eco-friendly
• Geometry limitations: deep undercuts, thin flanges, and complex internal geometries are difficult to mill
• Bur replacement cost: carbide burs wear with use and must be regularly replaced
• Lab dependency: requires digital dental lab or in-house CAD/CAM system
• Occlusal adjustments still needed: virtual articulation does not perfectly replicate dynamic occlusion in all patients

4. SLA 3D-Printed Occlusal Splint

4.1 Fabrication Workflow

4.2 Material

• Photopolymer resins: urethane dimethacrylate (UDMA), bis-GMA, or hybrid methacrylate-based resins
• Splint-specific resins: e.g., Formlabs Splint Resin, Cosmos Splint (Yller), SprintRay Night Guard
• Biocompatibility: must meet ISO 10993 for intraoral Class IIa medical device use

4.3 Mechanical Properties — Detailed Analysis

• Flexural strength: 50–100 MPa (SLA) vs 100–130 MPa (PMMA) — SLA is 15–30% lower
• This difference is material-specific and resin brand-dependent; some resins approach PMMA values under optimal conditions

• SLA photopolymer baseline flexural strength: 67.67 ± 1.54 MPa
• After thermocycling (10,000 cycles): 59.37 ± 8.80 MPa — significant reduction (p < 0.05)
• UDMA-based light-cured resin: 45.5 MPa baseline — significantly lower than both PMMA and SLA (p < 0.0001); however, showed better aging resistance (no significant change after thermocycling)
• Clinical implication: For severe bruxism with high occlusal forces, SLA splints may have shorter service life due to aging-related strength reduction

• Horizontal printing → significantly higher biaxial flexural strength and lower deformation vs vertical printing
• This is a critical fabrication variable often overlooked clinically
• Graphene nanoplatelet (GNP) addition did NOT improve strength
• With optimal horizontal orientation, SLA resins can reach comparable or even improved biaxial strength vs PMMA
• All specimens were non-cytotoxic to L929 and gingival stromal cells — confirming biocompatibility

• UV oven post-polymerization: best mechanical properties + least dimensional change
• Microwave post-polymerization with SLA: 40.2% shrinkage in occlusal splint resin — clinically unacceptable
• Recommendation: always use UV light oven for SLA splint post-curing, never microwave
• LCD (liquid crystal display) printing + UV post-polymerization showed highest flexural strength

• SLA mean RMS: 0.16 ± 0.02 mm — slightly less accurate than milled (0.11 ± 0.02 mm) and DLP (0.14 ± 0.02 mm)
• Clinical fit was poorest among SLA splints in this study, though differences may not be clinically significant for occlusal splints (vs surgical wafers where precision is critical)

4.4 Comparison with Conventional PMMA (Barbur et al., 2023; PMID: 37626652)

4.5 Advantages

• Fastest production time: printing can be completed in 2–6 hours including post-processing
• Lower cost per unit: resin cost and machine amortization are lower than milling
• No material waste: additive process — only resin that forms the splint is used
• Complex geometries possible: undercuts, thin walls, and intricate designs achievable
• Scalability: multiple splints can be printed simultaneously on one build platform
• Digital archiving: STL file stored; reprints possible if splint is lost or fractured
• Integration with intraoral scanning: fully digital workflow from scan to delivery
• Active area of research: flexible resins, multi-material printing, AI-driven occlusal design in development (Šimunović et al., 2025)

4.6 Disadvantages

• Lower mechanical properties: 15–30% lower flexural strength than heat-cured PMMA (Šimunović et al., 2025)
• Material heterogeneity: wide variation in properties between resin brands; no universal standard equivalent to ISO 20795-1 for PMMA
• Print orientation sensitivity: incorrect orientation drastically reduces strength (Janjić et al., 2024)
• Post-processing complexity: washing, support removal, and UV curing require specific equipment and protocols; errors cause poor fit or mechanical failure
• Aging concerns: thermocycling significantly reduces SLA flexural strength (Smardz et al., 2026)
• Surface roughness: as-printed surfaces are rougher than polished heat-cured PMMA; may harbour biofilm and require finishing
• Residual photopolymer / cytotoxicity: inadequately cured resins may leach residual monomers — though studies confirm biocompatibility of properly cured specimens (Janjić et al., 2024)
• Regulatory variability: not all 3D-printed resins are CE-marked or FDA-approved for intraoral use; clinicians must verify device classification (Rabel et al., 2024)

5. Ongoing Clinical Evidence: The Rabel et al. (2024) RCT Protocol

• Design: Prospective, randomized, single-blinded, crossover; monocentric
• Population: 40 participants — 20 bruxism, 20 pain-related TMD (DC/TMD diagnosed)
• Comparison: Michigan-type milled vs 3D-printed stabilization splints; both from CE-marked materials
• Wear protocol: Each splint worn for 3 months in random order; follow-up at 2 weeks and 3 months
• Outcomes:
  • Primary: Oral health-related quality of life (OHIP-G14)
  • Secondary: Patient satisfaction (VAS), therapeutic efficacy, antagonist wear, pain/disability (GCPS v2.0), splint fit, wear rate, fracture rate
• Status: Active — results awaited but will provide the first head-to-head RCT clinical outcome data

6. Comprehensive Head-to-Head Comparison

7. Clinical Recommendations for Thesis

1. Conventional heat-cured PMMA remains the gold standard for mechanical strength and remains the first-choice fabrication method in practices without digital infrastructure, and for severe bruxism cases demanding maximum splint durability.
2. CAD/CAM milled PMMA is the current best-practice digital method — superior dimensional accuracy (Lee et al., 2025), industrial-grade material properties, fully digital workflow, and archivability. Recommended for any practice with CAD/CAM capability, especially as part of a full-mouth digital rehabilitation workflow.
3. SLA 3D printing is clinically viable and rapidly advancing, with key advantages in speed, cost, and design flexibility. Print orientation (horizontal preferred) and UV post-curing are non-negotiable for acceptable mechanical properties (Janjić et al., 2024; de Gois Moreira et al., 2024). Not yet recommended as first-line for severe bruxism until RCT evidence from Rabel et al. (2024) is published.
4. All three methods produce clinically acceptable splints when fabrication protocols are strictly followed. The critical variables are not just technique but: post-processing protocol, material brand, print/processing parameters, and chairside occlusal adjustment.

References

1. Šimunović L, Čimić S, Meštrović S. Three-dimensionally printed splints in dentistry: a comprehensive review. Dent J (Basel). 2025;13(7):312. doi:10.3390/dj13070312. PMID: 40710156.
2. Smardz J, Kresse-Walczak K, Meißner H, Böning K, Weżgowiec J, Małysa A. The influence of thermal and mechanical aging on the flexural properties of conventional and 3D-printed materials used in occlusal splints manufacturing. Materials (Basel). 2026;19(2):421. doi:10.3390/ma19020421. PMID: 41598136.
3. Janjić K, Valentova A, Arellano S, Unterhuber A, Krause A, Oberoi G. The impact of print orientation and graphene nanoplatelets on biaxial flexural strength and cytotoxicity of a 3D-printable resin for occlusal splints. Dent Mater. 2024;40(11):1780–1789. doi:10.1016/j.dental.2024.07.031. PMID: 39117501.
4. de Gois Moreira FG, da Silva NR, Bezerra MGPG, et al. Influence of 3D printing system, postpolymerization and aging protocols on resin flexural strength and dimensional stability for printing occlusal splints, models and temporary restorations. Clin Oral Investig. 2024;28:589. doi:10.1007/s00784-024-05998-4. PMID: 39425803.
5. Barbur I, Opris H, Crisan B, et al. Statistical comparison of the mechanical properties of 3D-printed resin through triple-jetting technology and conventional PMMA in orthodontic occlusal splint manufacturing. Biomedicines. 2023;11(8):2155. doi:10.3390/biomedicines11082155. PMID: 37626652.
6. Lee CKJ, Yong CW, Tan SL, Seah JA, Chew MT, Ren Y. Accuracy and clinical fit of milled versus rapid prototyped orthognathic surgical splints. J Stomatol Oral Maxillofac Surg. 2025;126(2):102069. doi:10.1016/j.jormas.2024.102069. PMID: 39260569.
7. Rabel K, Lüchtenborg J, Linke M, 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;25(1):593. doi:10.1186/s13063-024-08437-7. PMID: 39238023.
8. Okeson JP. Management of Temporomandibular Disorders and Occlusion. 8th ed. St. Louis: Elsevier; 2019.
9. Schiffman E, Ohrbach R, Truelove E, et al. Diagnostic criteria for temporomandibular disorders (DC/TMD). J Oral Facial Pain Headache. 2014;28(1):6–27. PMID: 24482784.

For your thesis: This section fits best as a "Review of Literature" or "Materials and Methods — Background" chapter, particularly if your study involves fabricating and comparing splints using two or more of these techniques. If you are conducting an in-vitro study, the mechanical property data tables above can serve directly as reference benchmarks for your results discussion. Let me know if you need a specific comparison table, a statistical analysis framework, or a study design section.