Is nonsurgical management effective in temporomandibular joint disorders? - A systematic review and meta-analysis.

BACKGROUND: Various nonsurgical interventions have been used for the management of patients with temporomandibular joint (TMJ) disorders, but their clinical effectiveness remains unclear. Hence, the purpose of this systematic review and meta-analyses was to assess the evidence of the effectiveness of nonsurgical interventions in the management of TMJ disorders.
MATERIALS AND METHODS: A literature search on five databases such as PubMed, PubMed Central Cochrane, TRIP, NGCH databases and hand searching was conducted for a period from October 1995 to 2015. Randomized control trials (RCTs) on the nonsurgical management of TMJ disorders were included and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The quality of the articles was assessed by JADAD scoring. Finally, out of 23 RCTs, 11 articles having any of the primary outcomes (pain pressure threshold [PPT], pain, maximal pain-free mouth opening, and level of dysfunction) were selected. The extracted data were analyzed using NCSS software.
RESULTS: The results showed the evidence of pain reduction (P = 0.00), maximal pain-free mouth opening (P = 0.0138), and decrease in level of dysfunction (P = 0.0007) but no improvement in PPT to a significant level (P = 0.6600).
CONCLUSION: Our results suggest that the simplest, cost-effective nonsurgical treatments have a positive therapeutic effect on the initial management of TMJ disorders. However, a consistent methodology recording both the objective and subjective outcomes would be a better choice for added reliability.

INTRODUCTION

The phrase “temporomandibular disorders (TMDs)” is a collective term embracing a number of clinical problems that involve the masticatory musculature, the temporomandibular joint (TMJ) and associated structures, or both.[1] Symptoms of TMDs occur in approximately 6%–12% of the adult population.[2] The epidemiologic predilection of TMDs in women is striking. In the general population, TMDs are two times more prevalent in women than in men, whereas in patient population, these diseases have a female-to-male preponderance as high as 10:1.6.[3] A large proportion of women with TMDs are between 18 and 45 years of age.[4]

Due to a poor understanding of the etiology or pathogenesis of TMDs and the lack of definitive diagnostic or therapeutic approaches, patients often have to tolerate the symptoms, including debilitating pain, which substantially impact their quality of life over extended periods of time.[5] The treatment of TMD can be divided into two main groups. The first one being the nonsurgical therapy that includes treatments such as counseling, physiotherapy, pharmacotherapy, and occlusal splint therapy.[6] The other is the surgical therapy, and it ranges from TMJ arthrocentesis and arthroscopy to more complex open joint surgical procedures, referred as arthrotomy.[7] Narrative reviews indicate that the success rate of nonsurgical treatment is approximately 70%,[6] and the surgical treatment success is approximately 83%,[7] whereas other studies report approximately 40%–70% self-improvement without any treatments.[8] Systematic reviews, however, paint a different picture indicating that there is a lack of high-quality evidence to make informed clinical decisions. Yet, some systematic reviews do offer treatment guidance amidst some controversies about the most effective treatments.[9]

Various interventions have been suggested for TMDs, but to date, the most efficacious/effective approach is still unclear, which may result in a management based more on experience than evidence. The purpose of the current study, therefore, is to investigate the effectiveness of various nonsurgical interventions used in the management of TMDs.

MATERIALS AND METHODS

QUORUM guidelines [Appendix 1] were used to design, conduct, and analyze this systematic review and meta-analysis.

Aim

The aim of the study was to investigate the effectiveness of various nonsurgical interventions used in the management of TMJ disorders.

Objectives

The objectives of the study were to investigate different nonsurgical therapeutic options for the management of TMDs in terms of pain pressure threshold (PPT), pain, pain-free maximal mouth opening, and level of dysfunction by randomized controlled trials (RCTs).

Search strategy

PubMed, PubMed Central, Cochrane, TRIP, National Guideline Clearing House (NGCH) databases and hand searching of the reference lists of the included studies.

Inclusion criteria

This systematic review and meta-analysis were limited to RCTs for evaluating the efficacy of nonsurgical management of TMDs. All full-text RCTs that evaluated any type of nonsurgical management of TMDs against a placebo or sham or no treatment that were published in any language between October 1990 and 2015 with no previous surgery done in TMJ region.

Exclusion criteria

All other types of studies such as observational, non-RCTs, reviews, articles not indicating the treatment of TMDs, and interventions post-TMJ surgery were excluded from the study.

Data extraction

Full-text copies of all relevant and potentially relevant studies were obtained and assessed independently. All irrelevant records were excluded, and the reasons for their exclusion were noted.

Data analysis

The data analysis was performed using NCSS software (Kaysville, USA) to compare the effects of different interventions.

Outcomes assessed

Main symptoms and the reason for seeking treatment are pain, difficulty in maximum mouth opening, dysfunction in daily activity and reduced pain tolerance. For this reason, these outcomes were selected for determining the relative benefit of the study interventions.

Quality assessment

Each study was evaluated using 5-point JADAD scale[10] to assess the completeness and quality of reporting of RCTs as well as to assess potential bias in the trial. A trial scoring at least 3 out of 5 is considered to be of strong quality, whereas a score below 3 is considered to be methodologically weak.

RESULTS

Search

The search strategy identified a total of 7476 records from all databases ([435 – PubMed, 5732 – PubMed Central, 10 – Cochrane, 1217 – TRIP, 60 – NGCH, and hand searching – 22]). Of these, the full texts of 23 potentially eligible papers were retrieved and examined [Table 1]. Figure 1 presents the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format on how the trials were excluded from the meta-analysis.

Table 1

Characteristics of included studies

Figure 1

PRISMA flow diagram.

The systematic review and meta-analysis reviewed 23 full-text RCTs involving 1486 participants. Eleven RCTs in Table 1 had data and methods that allowed meta-analysis of the results comparing nonsurgical management with no treatment, placebo, or sham treatment which served as control. The results varied considerably in terms of PPT, pain, maximal mouth opening, and level of dysfunction.

Assessment of heterogeneity

The clinical and statistical heterogeneities were assessed across the studies before pooling. Clinical heterogeneity was determined by examination of each study's clinical characteristics for any diversity/variation in, for example, technique/delivery of interventions, severity/chronicity of condition, and treatment outcomes. Statistical heterogeneity was assessed by Chi-square test. A significant P < 0.05 for Chi-square test were considered substantial heterogeneity. A test for funnel plot asymmetry to assess publication bias was planned but was not performed because of insufficient numbers of studies pooled in the meta-analyses.

DISCUSSION

Meta-analysis of studies comparing two means – Pain pressure threshold

Figure 2 had data that allowed meta-analysis of the results comparing the nonsurgical methods such as acupuncture therapy, occlusal splint therapy, anterior repositioning splint (ARS), and NTI-tss with counseling and measured PPT for right and left TMJ. The results varied considerably.

Figure 2

Meta-analysis of studies comparing two means - pain pressure threshold.

The studies had proved that PPT can be slightly increased by the use of acupuncture therapy and occlusal splint therapy in 6-month duration for craniomandibular disorder patients,[13] whereas wearing splint alone for 3 months had no significant difference for TMJ disc displacement with reduction (DDWR) and arthralgia patients.[33]

In the forest plot associated with meta-analysis of combined studies, the mean difference between treatment and control group was found to be 0.074 which was statistically insignificant at P = 0.6600. This confirmed that there was no significant increase of PPT in patients treated with nonsurgical procedures.

Meta-analysis of studies comparing two means – Pain

Five studies compared the various nonsurgical treatment modalities such as acupuncture therapy and occlusal splint therapy, self-relaxation exercises, glucosamine sulfate therapy, gallium-aluminum-arsenide (Ga-Al-As) diode laser therapy, and diclofenac sodium, along with the use of cold/hot packs, soft food diet, and gentle mouth-opening exercise without flat occlusal appliance. Their effectiveness in reducing pain was shown in Figure 3.

Figure 3

Meta-analysis of studies comparing two means - pain.

A study has proved that craniomandibular disorder pain can be reduced by the use of acupuncture and occlusal splint therapy within 6 months.[13] Medication like diclofenac 25 mg and self-care protocol are required to treat the patients with anterior disc displacement without reduction (ADDWOR).[19] However, it is remarkable that, within 3-month duration, education alone led to a positive outcome impression and can be a good start in treatment of myofascial pain of the jaw muscles.[20] Patients with TMJ osteoarthritis had a greater relief from initial pain with glucosamine sulfate 400 mg and also for placebo capsules.[28] Recently, with the use of Ga-Al-As diode laser therapy, TMD pain was extremely reduced in just 2 weeks.[32]

However, on the contrary, ADDWOR reduction patients did not benefit from taking diclofenac sodium 25 mg along with a flat occlusal appliance during sleeping[19] and also other type of lasers such as helium–neon laser was also not found effective in reducing TMJ pain.[26]

The mean difference between treatment and control group using forest plot associated with meta-analysis of combined studies was 0.5098 which was statistically significant at P < 0.001. This implied that the successful outcome of pain reduction occurred in the intervention group than in control group.

Meta-analysis of studies comparing two means – Maximal pain and free mouth opening

Nonsurgical treatment methods such as soft splint, palliative treatment, posture training, glucosamine sulfate 400 mg, ARS with counseling, and diclofenac sodium 25 mg, along with the use of cold/hot packs, soft food diet, gentle mouth-opening exercises, flat occlusal splint, and self-relaxation exercises, are presented in Figure 4 with the meta-analysis which evaluated the efficacy of these methods in producing pain-free maximal mouth opening.

Figure 4

Meta-analysis of studies comparing two means - maximal pain-free mouth opening.

Soft splints,[14] posture training, and TMD self-management instructions[1720] aids in maximal pain-free mouth opening without producing occlusal changes in cases having masticatory muscle pain.[14] Patients with ADDWOR benefited from using the combination of diclofenac sodium, self-care protocol along with wearing a flat occlusal splint for 8 weeks.[19] Other study suggested that, irrespective of the medication given, pain-free mouth opening was improved with time in TMJ osteoarthritis.[28] TMJ DDWR and arthralgia patients required the use of ARS to ameliorate the pain during mouth opening.[33]

However, other nonsurgical treatments using diclofenac sodium 25 mg and instructions for a self-care protocol for ADDWOR,[19] NTI-tss along with counseling in patients having TMJ DDWR and arthralgia,[33] and the use of physical therapy program on ADDWOR[29] did not show significant improvement in maximal active and passive mouth opening in the treated group, thus not favoring the case group.

Forest plot associated with meta-analysis of the studies combined showed the mean difference between treatment and control group as 2.0356 which was statistically significant at P = 0.0138. This confirmed that the successful outcome of increased pain-free maximal mouth opening was in the intervention group than the control group.

Meta-analysis of studies comparing two means – Level of dysfunction

The studies which allowed meta-analysis and data synthesis are presented in Figure 5 showing the improvement of clinical dysfunction score (CDS) level using various nonsurgical managements such as acupuncture therapy, occlusal splint therapy, soft splint, and palliative treatment consisting of applying moist heat or ice, eating soft diet, decreasing parafunctional habits and caffeine consumption, modifying sleeping posture, and using over-the-counter medications, iontophoretic treatments, diclofenac sodium 25 mg along with the use of cold/hot packs, a soft food diet, gentle mouth-opening exercises without the use of flat occlusal splint.

Figure 5

Meta-analysis of studies comparing two means - level of dysfunction.

There is an evidence on the use of occlusal splint therapy to decrease the CDS in craniomandibular disorder patients.[13] The soft splint has the ability to decrease the Symptom Severity Index scores within 4–11 weeks in patients with masticatory muscle pain.[14]

TMJ DDWOR and TMJ capsulitis patients showed an improvement in the level of dysfunction within a week by the use of 0.5 ml of 0.4% dexamethasone sodium phosphate and 1 ml of 4% lidocaine hydrochloride.[15]

On the other hand, ADDWOR cases showed no improvement in dysfunction level on using diclofenac sodium 25 mg, self-care protocol along with a flat occlusal appliance when compared with control group, thus favoring the later.[19]

Using forest plot of meta-analysis of combined studies, the mean difference between treatment and control group was obtained as 0.3855 which was statistically significant at P = 0.007. This proved that the successful outcome of improving the level of dysfunction was in the intervention group than in control group.

Review of nonsurgical management that were not included in meta-analysis

Some of the studies in Table 1 could not be combined in meta-analysis due to differing study designs, interventions, and outcome assessed. However, the following nonsurgical treatments' modalities had its own benefits in TMD management.

While managing cases with TMJ disc displacement, balanced splint, canine-guided splint,[23] counseling,[11] adequate pain medication,[1118] and physical therapy[18] improved the participant's pain. There was also a reduction in muscle tenderness in most of the muscle spots evaluated. Joint sounds, mandibular movements,[23] and discomfort in daily life[18] all seemed to have improved. It was also proved in a study that mandibular condylar exercise had an increased success rate in maximal mouth opening and was as beneficial in the long term as any of the surgical interventions, which supports the importance of rehabilitation treatments before surgical intervention for disc displacement of TMJ.[27] Hence, more aggressive treatment modalities should not be used in the initial phase for such patients.[11]

Studies on TMD showed that a single intra-articular injection of sodium hyaluronate offered clear and consistent benefit of markedly lower incidence of relapse along with improvement in objective dysfunction scores for at least 6 months.[12] The low-cost therapies such as self-care strategies[22] and self-exercises are as effective as that of more expensive splint-based therapy in terms of pain reduction, increased mouth opening,[30] and overall improvement and hence are preferable than the later for TMDs.[22] However, pulsed electromagnetic fields had no specific treatment effects in those patients.[21]

A study on myofascial pain with Myofacial pain with limited opening (MLO) proved that, in addition to the natural course of time, brief cognitive behavior intervention promotes faster rate of improvement[16] and in whom first-line conservative treatment had failed have also been benefited by the use of neuroreflexotherapy.[24] Another study on myofascial pain, with or without functional disc displacement, showed that the patient can achieve a positive effect in pain and psychological status using botulinum toxin A injection within a month.[25]

Recently, it has been proved in a study that, starting a treatment with occlusal splint associated with an adjuvant nonsteroidal anti-inflammatory for a period of 10 days could be very adequate for a chronic masticatory muscle pain.[31]

Methodological limitations

There are several weaknesses in this review that need to be considered. With any systematic review, the validity of results is based on the ability to include all published reviews, the potential biases, and the quality of the RCTs reviewed.

Despite sincere attempt to include the majority of the published literature in both electronic and manual reviews, some relevant literature might have been missed

The recent articles that have got published after the commencement of this review might have been missed. Another factor is that the outcome selected was subjective experience such as pain, PPT, and level of dysfunction which are influenced by the patient's experience and relationship to treatment providers. Furthermore, the measurements and its conversion to a comparable measure may have introduced bias into the meta-analysis

Many other outcome measures including range of movements, deviation of jaw, joint noises, and adverse events were not included in many studies. Hence, the comparison of these outcomes was not possible.

CONCLUSION

From the results of meta-analysis, it can be concluded that nonsurgical treatment methods such as occlusal splints, pharmacological treatments, exercise, posture training, and low-level laser therapy showed evidence of pain improvement, maximal pain-free mouth opening, and a decrease in the level of dysfunction but failed to increase PPT level. Although this review and analysis points to using the simplest, least costly, nonsurgical treatments for the initial or concurrent management of TMDs to achieve a positive therapeutic effect, it is suggested that more studies with consistent methodology should be done for a definitive conclusion of the efficacy of different types of appliances and their comparative effectiveness relative to other common TMD treatments.

Future perspectives

Subgroup analysis and investigation of heterogeneity

If future studies record sufficient explicit data, a subgroup analysis according to age, gender, and the degree of severity of TMDs can be conducted along with the investigation of heterogeneity.

Sensitivity analysis

In future, if there are sufficient trials, following sensitivity analyses to assess the robustness of their review results, this analysis can be repeated after the exclusion of lower quality trials. In addition, sensitivity analyses to examine the effect of allocation concealment, blinded outcome assessment, and completeness of follow-up can be done.

Financial support and sponsorship

Nil.

Conflicts of interest

The authors of this manuscript declare that they have no conflicts of interest, real or perceived, financial or non-financial in this article.