Stability of physical therapy effects on temporomandibular disorder *

BACKGROUND AND OBJECTIVES: Physical therapy contributes to mitigate temporomandibular disorder symptoms because, in addition to stimulating proprioception and the production of joint synovial fluid, it improves adhered muscle fibers elasticity. This study aimed at evaluating the stability of therapeutic results in a follow-up period postphysical therapy in temporomandibular disorder patients. METHODS: Participated in the study 25 individuals of both genders, with temporomandibular disorder diagnosis. After a multimodal physical therapy program during 10 weeks, which included self-care guidance and home exercises, participants were re-evaluated by the Research Diagnostic Criteria for Temporomandibular Disorders and algometry. Results obtained immediately after treatment were compared to results of the evaluation carried out after two months of follow-up. RESULTS: From 25 participants, with mean age of 31.6 years, 76% had no temporomandibular disorder diagnosis immediately after treatment and from these, 68% have maintained this result in the two-month follow-up period. With regard to joint noises, 60% of participants have remained with no noises and pressure pain threshold values had no statistically significant differences between evaluations. CONCLUSION: Multimodal physical therapy intervention, combined with self-care guidance and home exercises has produced, in this study, positive and long-lasting effects on temporomandibular disorder symptoms, maintaining results for two months after treatment completion.


INTRODUCTION
Temporomandibular disorder (TMD) is characterized by functional or pathological change affecting the temporomandibular joint (TMJ), which may impair masticatory muscles and stomatognathic system.The number of TMD cases is continually increasing, probably due to current psychological stress, based on current etiologic factors, physical and systemic conditions, as well as psychological factors are ORIGINAL ARTICLE DOI 10.5935/1806-0013.20150002responsible for TMD orientation and maintenance 1,2 .TMD symptoms include persistent or recurrent pain in masticatory muscles or TMJ, jaw movement limitations or deviations, TMJ noises, joint discomfort and headache.In addition to impairing functionality, these factors considerably impact quality of life (QL) of these individuals [3][4][5] .To minimize TMD symptoms, manual therapy aims, by means of manipulation techniques, mobilization and specific exercises, at stimulating proprioception, producing adhered fibers elasticity, stimulating synovial fluid and promoting pain relief.So, when associated to other physical therapy techniques, it is very useful for treatment outcomes 6,7 .Guided home exercises and postural reeducation during daily life activities may help controlling TMD symptoms 8 .If combined with therapeutic exercises and manual therapy, they may be effective to treat disc displacement patients and those refractory to conventional treatments 9,10 .It is also worth stressing the effectiveness of the association of cervical therapy and orofacial treatment in patients with cervicogenig headache associated to TMD signs and symptoms 11 .Algometry is a widely used resource to study the effects of physical therapy on pain.It allows an objective measurement of pressure pain sensitivity, with high level of reliability, both to evaluate myofascial diseases and control group individuals 12,13 .In addition, algometry also contributes to infer the importance of the evaluation of other regions of the body of TMD patients, in addition to the craniofacial region 14 .More than evaluating results after physical therapy intervention, it is important to follow-up the maintenance of its therapeutic effects.So, this study aimed at evaluating therapeutic effects stability of a multimodal physical therapy program, by comparing TMD signs and symptoms, in addition to evaluating pressure pain threshold observed immediately after treatment and after a 2-month follow-up period.

METHODS
Participants were referred by the Orofacial Motility Laboratory where they were evaluated and treated with physical therapy for TMD.Participated in the study individuals of both genders, aged from 18 to 65 years and with diagnosis of TMD obtained by the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD).Patients were submitted to 10 weekly sessions lasting 45 minutes.All participants have signed the Free and Informed Consent Term.Data collected from participants' evaluation cards were: results of RDC/TMD evaluation, presence of joint noises, pain in muscle and joint regions, as well as pressure pain threshold in 16 muscles bilaterally evaluated: anterior, medial and posterior temporal, superior, medial and inferior masseter, sternocleidomastoid and superior trapezius.Pressure algometer -Force Dial Dynamometer ® FDK/FDN (Wagner Instruments) was used to evaluate pain threshold 9,12 .This tool may help diagnosis, in addition to checking the efficacy of myofascial pain treatments 13 .
Physical therapy program included a combination of therapeutic modalities, with focus on craniocervicomandibular system structures such as: therapeutic ultrasound, myofascial release, manual therapy, stretching and neuromuscular exercises, in addition to self-care and home exercises guidance 15 .This study has followed the application of modalities of the same protocol.This study has compared evaluation data immediately after treatment to the evaluation of the same variables in the follow-up period, to observe the maintenance of treatment effects.With regard to RDC/TMD diagnoses, 96% of patients have improved, not presenting any TMD diagnosis for the group without diagnosis, when evaluated immediately after treatment, and just one out of 25 evaluated individuals has maintained the same initial diagnosis.Shapiro-Wilk test was used to check data normality.Because data were not parametric, Wilcoxon test was used to compare algometry results between both evaluations, considering significant p<0.05 (95%).This study was approved by the institution's Ethics Committee under protocol 0281.0.243.000-08.

RESULTS
Participated in the study 25 individuals, being 20 females and 5 males, with mean age of 31.6±12.21years and 19 (76%) with good post-treatment evolution, that is, they had no TMD immediately after treatment.From these, 17 (68%) have maintained such result in the 2-month follow-up period, according to RDC/TMD evaluation.One patient (4%) has maintained the diagnosis of disc displacement with reduction, 4 (16%) who had some group II diagnosis (disc displacement) have evolved to no diagnosis, and 8% of those who after treatment had no TMD started to present some group I disorders (muscle disorders) (Figure 1), thus totaling 21 patients with no TMD diagnosis in this evaluation.There has been no significant difference in pressure pain threshold when comparing results immediately after treatment and two months after its completion (Table 1).Joint noises remained absent in 60% of patients.In 20% of pa-  With regard to pain at palpation, from 24 structures evaluated by RDC/TMD, 21 have maintained post-treatment results in the follow-up period, except to right inferior masseter, right lateral pterygoid and left temporal tendon.

DISCUSSION
In the evaluation of TMD diagnosis (RDC/TMD), 19 (76%) patients had no TMD diagnosis after treatment with a multimodal intervention protocol 15 and, according to results of this study, 17 (68%) patients had no TMD at 2-month follow-up evaluation.In 4 (16%) patients who still had the diagnosis after treatment, there has been disorder remission at 2-month follow-up evaluation.Through this intervention, authors have achieved a significant decrease in disorder severity, evaluated by the Temporomandibular index 15 , being that such therapeutic effects were maintained after a 2-month follow-up period.Results in line with our study may be attributed, in addition to the multimodal approach, to self-care and home exercises guidance also included in the intervention protocol, critical for the achievement of short and long-term results.
Based on pressure pain threshold results in the follow-up period, there have been no statistically significant changes in any muscle evaluated as compared to values obtained immediately after treatment.A different study, although not presenting statistically significant differences, has shown immediate pressure pain threshold increase of masseter and temporal muscles in patients with latent trigger points, immediately after treatment with manipulation or techniques for soft tissues, without observing the maintenance of such results 13 .With regard to noises, 60% have remained without them, 20% have decreased them and remaining patients had joint noises after 2-month follow-up.Statistically significant results show the positive effects of cervical manual therapy and of orofacial manual therapy associated to cervical manual therapy on TMD signs and cervical spine disorders 11 .
In agreement with our findings, authors have also observed that their results were maintained after a 6-month follow-up period.
Similar to our study, osteopathy and conventional treatment for TMD patients have shown that both were effective to relieve pain, increase maximum mouth opening amplitude and lateral head movement around its axis, being that such effects have remained after a 2-months follow-up period, considering the positive effects in the short and mediumterm.Values of visual analog scale, mouth movement amplitude and head rotation movements got worse for the osteopathy group during the 2-months follow-up period, as compared to re-evaluation immediately after treatment 16 .
A different study with 70 volunteers, has compared one group receiving just self-care guidance with TMD symptoms improvement in 57% of patients, to a group combining physical therapy (home exercises) and self-care guidance, with 77% improvement.The group practicing physical therapy and regular self-care has obtained masticatory muscles relaxation, pain relief and improvement in depression symptoms and sleep quality.Authors have indicated that self-care guidance, explanation of risk factors and training in home exercises provide physical and psychological gains, improving symptoms and patients' anxiety 17 .Some authors have investigated the effects of multimodal interventions on TMD signs and symptoms, which have been maintained even after physical therapy treatment completion, especially when this included passive and active mandibular and cervical exercises, relaxation techniques, postural correction and directed exercises 4,11,18 .With this, it is shown the importance of focusing on the craniocervicalmandibular system for the treatment of TMD patients, involving the spine and cervical muscles, since this system is one functional unit.In addition, this approach introduced in our study, may be an important contributing factor to maintain therapeutic results.Self-care exercises have proven benefits 19 and it is considered that, together with patients' education, they are relevant factors to maintain treatment and therapeutic continuity 20 .Also, they are not expensive and perpetuate physical therapy effects, the effect of which has durability, but its decrease is observed after two months 15,16 .
Our study had limitations, such as sample size and lack of investigators' blindness.Also, the scarcity and methodological heterogeneity of studies found on the subject, especially with regard to the maintenance of therapeutic effects, have limited our discussion.It is suggested that, to confirm the stability of therapeutic results, longer follow-up periods, above 6 months, should be evaluated.

CONCLUSION
Most patients have maintained the same results with regard to TMD diagnosis and presence of joint noises after two months of treatment.Treatment effects on pain have also remained, since there has been no difference in pressure pain threshold values evaluated immediately after and two months after treatment completion.So, physical therapy intervention was effective and with long-lasting effects for these patients.This result may be attributed to improved muscle balance and decreased joint overload obtained with the treatment, including the whole craniocervicomandibular system, as well as self-care and home exercises guidance, critical for the achievement and maintenance of therapeutic results.

Figure 1 .
Figure 1.Diagnosis of temporomandibular disorder after treatment and during follow-up

Table 1 .
Pressure pain threshold (kg/cm 2 ) immediately after treatment and follow-up R = righ; L = left.