METHODS

Compared to the Control group, the TMD group showed:

ü Greater global severity of signs and symptoms and greater global chewing difficulty (Table 1);

ü  A tendency to a less accurate and more asymmetric muscular recruitment in static (POC) and dynamic (chewing) activities (SMI, Table 1);

ü  Worse orofacial myofunctional conditions, with lower scores for tongue posture, jaw mobility and deglution function, and a predominant unilateral masticatory pattern (Table 2).

These findings may be subclinical characteristics of TMD patients with mild and recent involvement. Orofacial impairments during jaw mobility and deglutition, greater difficulty to chew, and the tendency to lower indices of coordination of muscle recruitment (EMG) suggests that these characteristics could be taken as predictors for the development of a more severe problem. However, a longitudinal study is required.

SUBCLINICAL CHARACTERISTICS OF THE TEMPOROMANDIBULAR DISORDERS

Claudia L.P. Ferreira1; Cláudia M. de Felício2, Gislaine A. Folha2, Matteo Zago1, Isabella Annoni1, Chiarella Sforza1

1 Department of Biomedical Sciences for Health, School of Medicine, Università degli Studi di Milano, Milan, Italy 2 Department of Otorhinolaryngology, Ophthalmology, and Head and Neck Surgery. School of Medicine of Ribeirão Preto, University of São Paulo, Brazil

claudialpferreira@gmail.com

!

INTRODUCTION

Knowing the initial manifestations of the temporomandibular disorders (TMD) is important for establish preventive measures or early interventions that help to avoid worsening the problem. Aim: To investigate which parameters of clinical and surface electromyographic (EMG) examinations are useful to characterize patients with mild and recent TMD.

CONCLUSION

RESULTS AND DISCUSSION

supported by

Table 1. Clinical questionnaires and EMG indices for the Control and TMD groups

Control (N = 18) TMD (N = 22) T test

Mean SD Mean SD P value

Questionnaires Global Severity of Signs and Symptoms (ProTMDMulti) (scores) 4.06 5.67 25.23 37.17 0.0003* Chewing difficulty (scores) 14 6.526 18.364 7.644 0.029*

EMG static indices

POC Temporal % 88.041 2.402 86.44 4.407 0.176

POC Masseter % 87.036 2.539 82.783 10.04 0.088

TORQUE % -1.731 4.166 5.054 19.717 0.217

ATTIV % -2.881 7.612 -3.574 20.677 0.617

EMG chewing indices

Symmetry (SMI%) 55.03 18.11 67.08 20.86 0.0615

Right Amplitude % 191.24 95.21 202.67 157.05 0.7883

Right Phase (degree) 29.24 37.88 30.41 22.13 0.9042

Left Amplitude % 155.23 85.64 132.15 85.99 0.4027

Left Phase (degree) 183.59 54.41 199.75 40.87 0.2903

TMD Group (N = 22) disk displacement with reduction (2a) associated to muscular (1a) and/or

arthralgia (3a) disorders

Control Group (N = 18) healthy subjects without TMD

complaints

ü  Mild Severity and Recent Onset ü  16 women and 6 men ü  mean age 21 years, SD 2 years

ü  10 women and 8 men ü  mean age 21 years, SD 2 years

Statistical Analysis: Categorical variables were analyzed by Mann-Whitney test, and continuous data by Student’s t-test for unpaired samples. Significance was set at p<0.05.

Figure 2. EMG recordings of MVC.

-  EMG potentials were standardized as % of MVC on cotton rolls;

-  EMG indices were calculated for MVC on dental surfaces: muscular symmetry (percentage overlapping coefficient, POC%), potential lateral displacing components (unbalanced contractile activities of contralateral masseter and temporalis muscles, Torque %), relative activity (most prevalent pair of masticatory muscles, ATTIV %) [5].

-  Bivariate analysis of the EMG potentials recorded during each chewing test was used to describe muscular coordination (Lissajous Plot). We calculated: Amplitude (differential activity of the muscles on the working and balancing sides); phase angle (degree); chewing frequency (Hz). Symmetrical Mastication Index (SMI,%) was computed to assess whether the left- and the right-side chewing tests were performed with symmetrical muscular patterns [3] (Figure 3).

Research Diagnostic Criteria for TMD, Axis I for diagnosis and TMD classification [1];

Questionnaires with numerical scales to determine the severity of perception of TMD signs and symptoms (ProTMDmulti-part II) [2] and difficulty to chewing [3];

Clinical evaluations of the components and functions of the stomatognathic system by Orofacial Myofunctional Evaluation with Scores (OMES Protocol) [4]

EMG of the right and left masseter and temporalis muscles were recorded during: (1) Maximum voluntary dental clench (MVC) with cotton rolls (reference test); (2)  MVC without cotton rolls (on dental surfaces); (3)  Unilateral, left and right, chewing of pre-softened sugarless gum.

Figure 1. Placement of the surface electrodes

maximum scores of the protocol

Control (N=18) TMD (N=22) Mann-Whitney’

mean SD mean SD P value Appearance/posture Lips 3 2.67 0.49 2.73 0.46 0.687 Mandible 3 2.61 0.5 2.59 0.5 0.9 cheek 3 2.89 0.32 3 0 0.114 Face 3 1.94 0.64 1.77 0.43 0.317 Tongue 3 2.89 0.32 2.45 0.67 0.016* Mobility Lips 12 10.56 1.89 11.09 1.48 0.32 Tongue 18 14.39 2.83 13.95 2.7 0.623 Mandible 15 14.17 1.1 12.45 1.47 0.000* Cheek 12 11.44 0.86 11.59 0.85 0.888 Functions Breathing 3 2.94 0.24 2.95 0.21 0.665 Deglutition 15 13.89 1.49 13.68 1.49 0.010* Chewing 10 9.39 1.14 8.36 1.22 0.523 Total Score of Orofacial Myofunctional Disorder 100

93.39 5.73 89.82 6.71 0.082

REFERENCES 1.  Dworkin, LeResche. J Craniomandib Disord 1992;6:301–55. 2.  Felício et al. Cranio 2009;27:62–7. 3.  Ferreira et al. J Electromyogr Kinesiol 2014; in press. 4.  Felicio et al. J Oral Rehabili2012;39:744–53. 5.  Tartaglia et al. Manual Therapy. 2008;13: 434-440.

Figure 3. Lissajous plot of differential left–right masseter activity (x-coordinate = M) and differential left–right temporal activity (y-coordinate = T). Unit: % of MVC on cotton rolls. Each dot represents a single chewing cycle. The Hotelling’s 95% confidence and standard ellipses are also drawn (left side: green; right side: red). Data from a control healthy subject, with good coordination and symmetry index (SMI) = 93.76%.

•  There were no differences between groups for the palpation pain scores, measures of jaw movements, chewing time and frequency, and EMG indices.

Table 2. Orofacial myofunctional conditions for Control and TMD groups