Oral splints for patients with temporomandibular disorders or bruxism: a systematic review and economic evaluation

Synthesis of temporomandibular disorders management intervention outcomes for development of core outcome sets: A systematic review

INTRODUCTION

The selection of appropriate outcomes in clinical trials and systematic reviews is a crucial factor in determining the results that are useful, reliable, and relevant for both patients and healthcare professionals. Clinicians and researchers have been encouraged to develop and apply core outcome sets (COS) to minimise the discrepancy between studies.

AIM

This systematic review is the first phase of the COS development project for clinical trials in temporomandibular disorders (COS-TMD). It aims to identify and synthesise the outcomes used in the randomised controlled trials (RCT) that evaluated the effectiveness of interventions used in TMD management.

MATERIALS AND METHODS

An electronic search was performed in several databases: MEDLINE (via PubMed), Scopus, Web of Science, Cochrane Library and EMBASE. The eligibility criteria comprised RCT that applied any intervention to treat temporomandibular joint disorders or masticatory muscle disorders. The identified outcomes were categorised according to domains of the Initiative on Methods, Measurement and Pain Assessment in Clinical Trials (IMMPACT).

RESULTS

The electronic search resulted in 1606 studies. After removing duplicates and applying the eligibility criteria, 106 RCT were included. A total of 43 studies evaluated masticatory muscle disorders, 27 evaluated temporomandibular joint disorders, and 36 analysed mixed TMD.

CONCLUSIONS

The evaluation showed significant variability in the types of outcomes and their measurement instruments. In addition, some domains such as physical and emotional functioning, participant ratings of global improvement and adverse events have been neglected when determining the effectiveness of treatments for TMD.

Effects of different interventions on bruxism: an overview of systematic reviews

OBJECTIVE

This study aimed to evaluate, qualify, and summarize evidence presented in systematic reviews (SR) on treatments for bruxism.

METHODS

The overview was conducted using the PICO strategy: children, adolescents, and adults with bruxism (P) were submitted to different treatments (I) compared to other treatments, placebo, or no treatment (C) in order to evaluate incidence, prevalence, and number of episodes of bruxism (O). The search was carried out in six databases and gray literature up to July 2023. Data were extracted, and the ROBS tool was used, followed by a descriptive synthesis of the results.

RESULTS

A total of 31 SR were included. Sixteen showed a positive effect on episodes of bruxism (BE), while two had negative, one had neutral, and nine had inconclusive effects. Using the risk of bias in systematic reviews tool (ROBIS), risk of bias varied from low (n = 23) to high (n = 5) among the SR. Pharmacological treatment, oral rehabilitation, and other therapeutic approaches presented inconclusive or negative effects on BE, while oral appliances showed controversial effects. Biofeedback, physical therapy, laser therapy, and botulinum toxin showed positive effects on the reduction of BE.

CONCLUSION

Biofeedback, physical therapy, laser therapy, and botulinum toxin showed positive effects on the reduction of BE; there is still a lack of studies to support the safe and long-term use of these therapies.

REGISTRATION NUMBER

PROSPERO CRD42021273905.

Temporomandibular Disorders Management-What's New? A Scoping Review

Temporomandibular disorders include various conditions that impact the masticatory system, affecting its structure, function, or physiology. Clinicians face a complex array of therapeutic options when treating this group of diseases, emphasizing the importance of evaluating the current evidence to guide decisions in patient care. The main objective of this article is to conduct a scoping review on the available treatment approaches to manage temporomandibular disorders (TMDs). An extensive search of the literature was performed on Scopus, Pubmed, Embase, and Web of Science. Systematic reviews published in the last 5 years were considered. Out of the 2183 publications identified, 109 studies were included in this review. Among them, 39 articles focused on the non-invasive approach, while 120 delved into the minimally invasive approach, and 15 explored the surgical approach. Non-invasive or conservative approaches like cognitive-behavioral therapy, physical therapy, and acupuncture offer effective pain management and functional improvements in TMDs. Emerging treatments offer promising alternatives for treating these disorders. Surgery should be reserved for severe cases, with conservative therapies used in conjunction with invasive procedures for optimal patient outcomes.

Literature Review of an Anterior Deprogrammer to Determine the Centric Relation and Presentation of Cases

The increasing demand for dental aesthetics, articulation corrections, and solutions for pain and frequent bruxism demands quick and effective restorative dental management. The biomedical research aimed to create a beneficial, ecological, and readily available anterior deprogrammer to determine the centric relation (CR) of cases. This medical device is additively manufactured from a biocompatible material. Size is customizable based on the width of the patient's anterior central incisors. This is a pilot study with two subjects. The task was to develop a complete data protocol for the production process, computer-aided design (CAD), and three-dimensional (3D) printing of the anterior deprogrammers. The research focused on creating simple and practically applicable tools for the dentist's prescription (anterior deprogrammer in three sizes), and secondly for the communication between the dentist and the patient (computer application). The tested hypothesis was whether, according to these novel tools, it is possible to produce functional occlusal splints, which could be manufactured using current technologies. This study compared a traditional splint with a digitally designed and 3D-printed one. The tested hypothesis was whether manufactured occlusal splints differ in patients' subjective perception of comfort. Each conservative treatment was monitored for ten weeks. Initial results are promising; no statistically significant difference was found between the productive technologies.

Effects of Polishing and Artificial Aging on Mechanical Properties of Dental LT Clear® Resin

Three-dimensional printing has become incorporated into various aspects of everyday life, including dentistry. Novel materials are being introduced rapidly. One such material is Dental LT Clear by Formlabs, a resin used for manufacturing occlusal splints, aligners, and orthodontic retainers. In this study, a total of 240 specimens, comprising two shapes (dumbbell and rectangular), were evaluated through compression and tensile tests. The compression tests revealed that the specimens were neither polished nor aged. However, after polishing, the compression modulus values decreased significantly. Specifically, the unpolished and nonaged specimens measured 0.87 ± 0.02, whereas the polished group measured 0.086 ± 0.03. The results were significantly affected by artificial aging. The polished group measured 0.73 ± 0.05, while the unpolished group measured 0.73 ± 0.03. In contrast, the tensile test proved that the specimens showed the highest resistance when the polishing was applied. The artificial aging influenced the tensile test and reduced the force needed to damage the specimens. The tensile modulus had the highest value when polishing was applied (3.00 ± 0.11). The conclusions drawn from these findings are as follows: 1. Polishing does not change the properties of the examined resin. 2. Artificial aging reduces resistance in both compression and tensile tests. 3. Polishing reduces the damage to the specimens in the aging process.

Efficiency of occlusal splint therapy on orofacial muscle pain reduction: a systematic review

BACKGROUND

This systematic review aims to examine the existing original studies to determine the effectiveness of occlusal splints (OSs) in the management of orofacial myalgia and myofascial pain (MP) in comparison with no treatment or other interventions.

MATERIALS AND METHODS

Based on the inclusion and exclusion criteria of this systematic review, randomized controlled trials were qualified, in which the effectiveness of occlusal splint therapy in the management of muscle pain was examined in comparison with no treatment or other interventions. This systematic review was conducted according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020. The authors searched three databases (PubMed, CINAHL (The Cumulative Index to Nursing and Allied Health Literature) and Scopus) for English publications published between January 1, 2010, and June 1, 2022. The last database search was carried out on June 4, 2022. Data were extracted from the included studies and assessed for risk of bias using the revised Cochrane risk-of-bias tool for randomized trials.

RESULTS

Thirteen studies were identified for inclusion in this review. In total, 589 patients were diagnosed with orofacial muscle pain who underwent education and various forms of therapy including different types of OSs, light emitting diode therapy, acupuncture, low-level laser therapy, device-supported sensorimotor training, Kinesio Taping, myofunctional therapy, and physical therapy. All studies included demonstrated a high risk of bias.

CONCLUSIONS

There is insufficient evidence regarding whether OS therapy in the treatment of orofacial myalgia and MP offers an advantage over other forms of interventions or no treatment. Further reliable clinical studies in this area are needed to improve the quality of research, which should be performed with larger groups of blinded respondents and controls.

CLINICAL RELEVANCE

Due to the large-scale nature of orofacial muscle pain, it is assumed that each dental clinician will meet patients with orofacial muscle pain repeatedly in daily practice; hence, the review of the effectiveness of OSs in the management of orofacial myalgia and MP is necessary.

Influence of Soft Stabilization Splint on Electromyographic Patterns in Masticatory and Neck Muscles in Healthy Women

This study investigates the influence of soft stabilization splints on electromyographic patterns in masticatory and neck muscles in healthy women. A total of 70 healthy women were qualified for the research. The resting and clenching electromyographic patterns of the temporalis (TA), masseter (MM), digastric (DA), and sternocleidomastoid (SCM) muscles were measured using the BioEMG III™ apparatus. The interaction between splint application and resting muscle activity affected the results in all examined muscles except the temporalis muscle. A large effect size was observed in masseter (2.19 µV vs. 5.18 µV; p = 0.00; ES = 1.00) and digastric (1.89 µV vs. 3.17 µV; p = 0.00; ES = 1.00) both-sided RMS activity. Significant differences between the two conditions were observed in all Functional Clenching Indices (FCI) for MM, SDM, and DA muscles. All FCI values for the MM and DA muscles were significantly lower with than without the splint. We observed an increase in all activity indices due to splint application, which suggests a masseter muscle advantage during measurement. The soft stabilization splint influenced resting and functional activity in the MM, SDM, and DA muscles. During tooth clenching, a soft stabilization splint changed the involvement proportions of the temporalis and masseter muscles, transferring the main activity to the masseter muscles. Using a soft stabilization splint did not affect the symmetry of the electromyographic activity of the masticatory and neck muscles.

The Efficacy of Manual Therapy Approaches on Pain, Maximum Mouth Opening and Disability in Temporomandibular Disorders: A Systematic Review of Randomised Controlled Trials

Temporomandibular disorder (TMD) is a common condition disabling people and bringing up costs. The aim of this study was to investigate the effects of manual therapy on pain intensity, maximum mouth opening (MMO) and disability. Searches were conducted in six databases for randomised controlled trials (RCTs). Selection of trials, data extraction and methodological quality assessment were conducted by two reviewers with discrepancies resolved by a third reviewer. Estimates were presented as mean differences (MDs) or standardized mean differences (SMDs) with 95% confidence intervals (CIs). Quality of the evidence was assessed using the GRADE approach. Twenty trials met the eligibility criteria and were included. For pain intensity, high and moderate quality evidence demonstrated the additional effects of manual therapy at short- (95% CI -2.12 to -0.82 points) and long-term (95% CI -2.17 to -0.40 points) on the 0-10 points scale. For MMO, moderate to high quality evidence was found in favour of manual therapy alone (95% CI 0.01 to 7.30 mm) and its additional effects (95% CI 1.58 to 3.58 mm) at short- and long-term (95% CI 1.22 to 8.40 mm). Moderate quality evidence demonstrated an additional effect of manual therapy for disability (95% CI = -0.87 to -0.14). Evidence supports manual therapy as effective for TMD.

Oral splints in the management of nociceptive pain and migraines: A scoping review

Temporomandibular disorders (TMDs) are characterized by numerous pain manifestations. Their treatment often involves the use of an oral splint. Recent research has found a relationship between migraines, nociceptive pain and TMDs. The aim of the present study was to perform a scoping review of studies in order to evaluate the effectiveness of the various types of oral splint in the treatment of migraine or nociceptive pain. Publications were retrieved from seven databases (PubMed, Web of Science, EMBASE, Scopus, ProQuest, SpringerLink and Ovid). Out of the 15 included publications, three studies were before and after studies, with no control group, whereas the other twelve studies were clinical trials, among which two publications were crossover studies. A clear, single distinction of pain was difficult to describe. Therefore, numerous publications focused on a combination of various types of pains, including myofascial, temporomandibular joint, headaches and migraine-like symptoms, all of which mimicked TMD pain. Overall, six studies used the stabilization splint (SS), three explored the comparison between the SS and the nociceptive trigeminal inhibition splint (NTIS) and two the NTIS. The majority of publications reported a positive outcome of splint therapy. Regarding the type of oral splint usage, the most commonly used one was the SS, followed by the NTIS. The definition and assessment of pain were heterogenous in the identified articles. The findings of the current study showed that occlusal splints may help with pain management, and that effective treatment of TMD-related pain at an early stage can enhance the quality of life of patients.

High Pain Intensity is a Risk Factor of Non-Resolving TMD: A Three-Year Follow-Up of a Patient Group in a Norwegian Interdisciplinary Evaluation Program

Purpose

To investigate the outcome of patients with long-term refractory temporomandibular disorders (TMD) three years after a Norwegian interdisciplinary evaluation program with attention to patient satisfaction, function, pain, and psychosocial variables.

Patients and Methods

The study population consisted of 60 long-term refractory TMD patients who were investigated by a Norwegian interdisciplinary team. A questionnaire that covered medical history, function, pain, lifestyle factors, TMD-status and follow-up from their general medical practitioner (GMP) was sent to the patients three years after the evaluation. Questionnaires that assessed function (Mandibular Functional Index Questionnaire [MFIQ] and Roland Morrison Scale [RMS]), pain intensity (General Pain Intensity questionnaire [GPI]) and psychosocial factors (Hospital Anxiety and Depression scale [HADS]); a 2-item version of the Coping Strategies Questionnaire [CSQ]) were included in the package.

Results

Thirty-nine out of 60 TMD patients completed the questionnaires. Improvements in TMD symptoms were reported in 10 patients (26%), were unchanged in 16 patients (41%) and worsened in 13 patients (33%). Only 8 patients (21%) were satisfied with the follow-up of the suggested treatments from their GMP. Significant improvements of symptoms were noted in MFIQ (jaw function), GPI (including pain intensity at maximum and suffering from pain), and CSQ (pain related catastrophizing), in all 39 TMD patients as one group. However, a subgroup analysis showed that the significant improvements were mostly within patients who reported improvement of TMD symptoms. A high pain intensity at baseline was a significant risk factor (OR = 5.79, 95% CI: 1.34, 24.96) for patients who reported worsening of TMD symptoms at follow-up.

Conclusion

High pain intensity at baseline was a significant risk factor for poorer recovery three years after an interdisciplinary evaluation. Our data support the notion that improved coping with TMD pain includes both decreased pain intensity, CSQ and MFIQ scores.

Development of core outcome sets for clinical trials in temporomandibular disorders: A study protocol

Background

Temporomandibular Disorder (TMD) is a generic term applied to describe musculoskeletal disorders that affect the temporomandibular joint (TMJ), the masticatory muscles and the related structures. TMD comprises two groups of disorders, namely intra-articular TMD and masticatory muscle disorders. There is still difficulty in establishing the effectiveness of different therapeutic modalities for TMD with robust evidence, despite the large volume of publications in the area. The lack of outcomes standardization may represent a limiting factor in the search for scientific evidence.

Objective

This study aims to develop a core outcome sets (COS) for clinical trials in intra-articular TMD and masticatory muscle disorders.

Methods

The protocol for determining the COS-TMD will consist of three phases: 1. Synthesis of TMD Management Intervention Outcomes. The identification of outcomes will be carried out through a systematic review, which will include randomized clinical trials that evaluated the effectiveness of interventions used in TMD management. 2. Through a two-round international Delphi survey, the list of outcomes will be scored by three panels of stakeholders. 3. A representative sample of key stakeholders will be invited to participate in a face-to-face meeting where they can discuss the results of the Delphi survey and determine the final core set.

Conclusions

The implementation of this protocol will determine the COS-TMD, which will be made available for use in all TMD clinical studies. The use of COS when planning and reporting TMD clinical trials will reduce the risk of publication bias and enable proper comparison of results found by different studies.

Management of temporomandibular disorders: a rapid review of systematic reviews and guidelines

Temporomandibular disorders (TMD) impact a significant proportion of the population. Given the range of management strategies, contemporary care should be evidence-informed for different TMD types. A knowledge-to-action rapid review of systematic reviews published in the past 5 years and guidelines published in the past 10 years concerning the management of TMD was conducted. The Cochrane, Embase, MEDLINE, PEDro, and PubMed databases were searched. A qualitative data analysis was undertaken, with quality assessment completed using the AMSTAR 2 checklist. In total, 62 systematic reviews and nine guidelines considering a range of treatment modalities were included. In concordance with current guidelines, moderate evidence supports a multi-modal conservative approach towards initial management. Contrary to existing guidelines, occlusal splint therapy is not recommended due to a lack of supporting evidence. The evidence surrounding oral and topical pharmacotherapeutics for chronic TMD is low, whilst the evidence supporting injected pharmacotherapeutics is low to moderate. In concordance with current guidelines, moderate quality evidence supports the use of arthrocentesis or arthroscopy for arthrogenous TMD insufficiently managed by conservative measures, and open joint surgery for severe arthrogenous disease. Based on this, a management pathway showing escalation of treatment from conservative to invasive is proposed.

Cytotoxicity of printed resin-based splint materials

OBJECTIVES

Printed splints may be an alternative as a treatment of functional disorders in addition to physical, manual and physiological therapeutics. The objective is to investigate whether different 3D printed splint materials, which are fabricated with different fabrication orientation and post-processing (washing and post polymerisation) exhibit different in vitro cytotoxicity.

MATERIAL AND METHODS

600 discs (n = 25 per group, 5mmx1mm) were printed (P30+ DLP-printer, Straumann, CH; 100 µm layer) from splint materials (M1: Luxaprint OrthoPlus, DMG, G; M2: V-Print Splint, Voco, G). Printing was performed under 90° (A1), 45° (A2) or 0° (A3) alignment to the building platform. Specimens were either automatically washed (W1) (Straumann P Wash, Straumann, CH) or manually cleaned (W2) (Voco Pre-/Main-Clean protocol, Voco, G), and post polymerization was performed (P1: Cure, Straumann, CH; P2: Otoflash N171, Ernst Hinrichs Dental, G). RAW264.7 mouse macrophages were exposed to extracts of the specimens and cytotoxicity was determined as cell survival using a crystal violet assay. Optical density values obtained from exposed cell cultures were normalized to untreated controls (100%), summarized as means and statistically analyzed (ANOVA, α=0.05).

RESULTS

Cell survival varied between 9.1+/-1.3% (alignment A2/post cure P2/material M2/wash system W2) and 58.5+/-5.9% (alignment A1/post cure P1/material M1/wash system W1). Univariate analysis of variance revealed significant differences between mean values for post cure (p = 0.000), wash system (p = 0.002) and materials (p = 0.000), but not for the alignment (p = 0.406). With standardised washing and adapted post cure, both tested materials provided lowest cytotoxicity even in all three printing alignments.

CONCLUSIONS

The selection of the material as well as the post-processing (post-polymerization, washing procedure) show influence on the in vitro cytotoxicity. Alignment during manufacturing does not affect toxicity.

CLINICAL RELEVANCE

Materials, washing and post-polymerization should be matched to reduce cytotoxic effects during additive manufacturing.

Do the Mandibular Condyles Change Their Positions within Glenoid Fossae after Occlusal Splint Therapy Combined with Physiotherapy in Patients Diagnosed with Temporomandibular Joint Disorders? A Prospective Case Control Study

The research question was: do the mandibular condyles change their position within glenoid fossae after treatment combining occlusal splint therapy and physiotherapy in patients diagnosed with temporomandibular disorders (TMD)? Forty patients with TMD were included into the study. They underwent initial physiotherapy, and a six-month treatment of occlusal splint therapy with physiotherapy. Cone-beam computed tomography images of temporomandibular joints (TMJs) were taken before and after the treatment. The control group consisted of 15 asymptomatic patients, who did not receive any type of occlusal treatment. The changes in the dimension of anterior, superior, posterior, and medial joint spaces after the end of the treatment in patients with TMD were statistically insignificant. The average value of condylar ratio was significantly higher after the end of the treatment (p = 0.025). The changes in the condylar sagittal position were statistically insignificant. Occlusal splint therapy with physiotherapy did not change significantly the dimension of joint spaces, nor placed the mandibular condyles into the centric relation. Treatment of patients with TMD should not aim at gnathological concept of placing the mandibular condyles into centric relation, because centric relation appears not to be mandatory to achieve successful results of treatment in patients with TMD.

What conservative interventions improve bite function in those with temporomandibular disorders? A systematic review using self-reported and physical measures

BACKGROUND

Bite is an important function of the human stomatognathic system. Despite this, it is commonly impaired in temporomandibular disorder (TMD) populations. The aim of this review is to evaluate the effectiveness of conservative interventions on self-reported and physical measures of bite function in individuals with TMD.

METHODS

This review was performed in compliance with PRISMA guidelines. An electronic search was performed on databases including Pubmed, CINAHL, Embase, and Cochrane Central. Inclusion criteria were journal articles evaluating the effect of any non-pharmacological conservative interventions on bite function in participants diagnosed with TMD. Risk of bias for individual studies was assessed using the Cochrane risk-of-bias v2 tool, and the NIH NHLBI pre-post tool. Data was synthesised based on outcome measures of bite function, and the quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Eleven studies were eligible for this review. Interventions included splinting, photobiomodulation, needling, exercise, manual therapy, and patient education; which were evaluated using mastication-related pain, self-reported chewing difficulty, and bite force/endurance outcome measures. Findings suggested manual therapy, needling, oral splinting, exercise and PBM interventions may improve bite function in TMD, although confidence in cumulative evidence ranged from moderate to very low. There was no evidence that patient education improved bite function.

CONCLUSION

Conservative interventions may be helpful to address bite-related impairments associated with TMD, although further research is needed to improve the quality of evidence and direct clinical guidelines.

Dynamic fatigue of 3D-printed splint materials

OBJECTIVES

Printed splints may be an alternative treatment for functional disorders. In addition to the selection of materials, the influence of cleaning or polymerisation can affect the dynamic behaviour and fatigue limit of printed materials.

MATERIAL AND METHODS

96 discs (n = 6 per group, 16mmx2mm) were printed (P30+ DLP-printer, Straumann, CH; 100 μm layer) from splint materials (M1: Luxaprint OrthoPlus, DMG, G; M2: V-Print Splint, Voco, G). Specimens were either automatically cleaned (C1: Straumann P Wash, Straumann, CH) or manually cleaned (C2: Voco Pre-/Main-Clean protocol, Voco, G). Post polymerisation was performed with LED (P1: Cure, Straumann, CH) or Xenon light (P2: Otoflash N171, Ernst Hinrichs Dental, G). The flexural fatigue limit was determined under cyclic loading in terms of a staircase approach with a piston-on-3-ball-test according to ISO 6872 after 24 h or 60 days water storage (37 °C). Specimens were preloaded with 50N and dynamic force was applied for 10⁵ loadings per step (f = 3Hz; steps 1: 50N-100N, 2: 50N-150N, 3: 50N-200N, 4: 50N-250N; F1000, Prematec, G; water at 37 °C).

STATISTICS

Kaplan Maier Log Rank (Mantel-Cox) test, ANOVA, Pearson correlations, Levene-test (α = 0.05, SPSS 26.0, IBM, Armonk, NY, USA)).

RESULTS

Mean survival cycles after 24 h of storage varied between 40388 (M1C2P2) and 195140 (M2C2P1) cycles and after 60 d decreased to 14022 (M1C2P2) and 173237 (M2C1P1). Kaplan Maier Log Rank test revealed significant differences between the material combinations. For M1 cleaning (Pearson: 0.346, p = 0.016) and for M2 polymerisation (Pearson: 0.616, p = 0.000) significantly influenced the number of loading cycles. Intermediate effects were found for material (p = 0.026), cleaning (p = 0.024) and polymerisation (p = 0.000) as well as the combination of material and polymerisation (p = 0.008).

CONCLUSIONS

The results show that the number of possible loading cycles of additively manufactured splint specimens depends on the type of material, their cleaning and post-polymerisation.

CLINICAL SIGNIFICANCE

Materials, cleaning and post-polymerisation of additive manufacturing processes should be matched to improve dynamic loading performance of splint materials.

Effects of low-level laser therapy versus soft occlusive splints on mouth opening and surface electromyography in females with temporomandibular dysfunction: A randomized-controlled study

Background

Low level lasers have been used as an alternative pain relief therapy for muscle and joint pain, since it induces analgesic, anti-inflammatory, and biomodulation effects of the physiological cell functions. The effectiveness of low-level laser therapy in temporomandibular joint dysfunction (TMD) treatment, however, is not well established. Although Surface electromyography (sEMG) has been suggested as a complementary means in TMD diagnosis, the effect of conservative treatments on muscle activity has not yet been thoroughly correlated with (sEMG) findings.

Purpose

To assess the efficacy of low-level laser therapy (LLLT) as compared to occlusive splint therapy (OST) on the TMJ opening index (TOI) and sEMG of masticatory muscles.

Materials and methods

112 female subjects suffering from unilateral myogenous TMD, aged 21–30 years-old, were recruited and divided into three groups: LLLT; soft occlusive splint therapy OST and a waitlist group as controls.

Outcome measures

TMJ opening index (TOI), Visual analogue scale (VAS), surface electromyography (sEMG).

Results

A significant reduction was reported in TOI, VAS and the sEMG within the LLLT and OST groups as well as significant decrease in all outcomes between groups in favor of the LLLT group (P< 0.0001). Meanwhile, there was a weak significant difference within the control group probably attributed to the analgesic. Post-hoc pairwise comparisons between groups [control vs occlusive splints, control vs low-level laser and low-level laser vs occlusive splints] revealed significant differences in the VAS and TOI [P = 0.0001; 95% CI: 0.9–2.2, 1.61–4.01, 0.65–1.96].

Conclusions

Findings support an evident short term therapeutic effect of the LLLT on improving VAS, TOI and sEMG in females suffering from myogenous TMD.

Pilot in-vitro study on insertion/removal performance of hand-cast, milled and 3D printed splints

OBJECTIVES

The aim of this in-vitro pilot study was to establish a splint testing method and compare insertion/removal performance of dental splints.

MATERIALS AND METHODS

56 identical lower jaw splints (n = 8 per group) were manufactured from 2x methacrylate (MA) hand-cast (reference material), deep-drawn Polyethyleneterephthalate, combined deep-draw MA hand-cast, 2x CAD/CAM-milled MA and 3D-printed MA systems. After 10 days water storage (37 °C), cyclic pull-off and insertion performance on a metal jaw was investigated. Statistics; Shapiro-Wilk-test, one-way-ANOVA; post-hoc-Bonferroni, Kaplan-Meier-survival, α = 0.05.

RESULTS

Mean insertion/pull-off cycles varied significantly (p = 0.000) between 864 cycles (MA) and 202640 cycles (Deep Draw MA). Fracture of the splints was characterized by brittle individual fractures in the 31-34 region and most fractures in region 35 (44 of 56 splints). Finite element analysis confirmed the type and location of failure.

CONCLUSIONS

Deep-draw, cast methacrylate and combined systems showed longer insertion/pull-off system cycles in comparison to printed or milled splints. Insertion/pull-off performance showed differences between the tested splint systems and indicates the influence of the processing.

CLINICAL RELEVANCE

The presented in-vitro test allowed for estimating the clinical insertion/pull-off performance of dental splints.

Personalized Biomechanical Analysis of the Mandible Teeth Behavior in the Treatment of Masticatory Muscles Parafunction

A 3D finite element model of the mandible dentition was developed, including 14 teeth, a periodontal ligament (PDL), and a splint made of polymethylmethacrylate (PMMA). The study considered three design options: 1—the case of splint absence; 2—the case of the splint presence installed after manufacture; and 3—the case of splint presence installed after correction (grinding) performed to ensure a uniform distribution of occlusal force between the teeth. For cases of absence and presence of splint, three measurements of the functional load were performed using the T-Scan III software and hardware complex (TekScan, Boston, MA, USA). It was found that the presence of a splint led to a decrease in the total value of the occlusive load and to a uniform distribution between all the mandible teeth. The occlusal force was considered as a static vertical force evenly distributed between the nodes belonging to the occlusive surface of the corresponding tooth for the first design option and the occlusal surface of the splint for the second and third ones, respectively. As a result of the study, it was concluded that the splint usage was effective in order to change the distribution of the functional load during the treatment of proved masticatory muscles’ parafunction; the safety of using a splint for teeth and surrounding tissues under the influence of the considered functional load was shown; the potential applicability of PMMA as a structural material of a splint that had been used for the treatment of masticatory muscles’ parafunction was established.