Laypeople's perceptions of frontal smile esthetics: A systematic review.

INTRODUCTION: The emphasis on dental esthetics has increased in recent years. There are, however, differences in esthetic perceptions among professional and lay groups. The aim of this comprehensive review was to update previous reviews and answer the following research question: Can lay thresholds for acceptance of smile esthetic anomalies be defined? METHODS: A systematic search in the medical literature (PubMed, PMC, NLM, Embase, Cochrane Central Register of Controlled Clinical trials, Web of Knowledge, Scopus, Google Scholar, and LILACs) was performed to identify all peer-reviewed articles reporting data regarding evaluations of laypeople's perceptions of dental esthetic factors. RESULTS: Of the 6032 analyzed articles, 66 studies were selected for the final review process. Among the selected articles investigated perceptions of diastema, 15 analyzed modifications in tooth size and shape, 8 considered incisor positions, 15 evaluated midline discrepancies, 16 investigated buccal corridors, 26 analyzed gingival display and design, 3 considered lip height, and 20 investigated miscellaneous factors. Threshold values were identified for the following features: diastema (0-2 mm), tooth size and shape of incisor position, midline discrepancy (0-3 mm), buccal corridors (5-16 mm), gingival exposure (1.5-4 mm), occlusal canting (0°-4°), and overbite (2-5 mm). Furthermore, few other smile characteristics were found to be significantly associated with perception of smile aesthetics, even though any threshold could be detected. CONCLUSIONS: On the basis of the obtained results, threshold values for the main features of smile and dental esthetics could be identified. Limitations of the present study were the heterogeneity of data which made it impossible to perform a meta-analysis, and the lack of information about sample selection and selective outcome reporting.

Children's perceptions of smile esthetics and their influence on social judgment.

OBJECTIVE: To define a threshold of acceptance of smile esthetics for children and adolescents. MATERIALS AND METHODS: A systematic search in the medical literature (PubMed, PubMed Central, National Library of Medicine's Medline, Embase, Cochrane Central Register of Controlled Clinical Trials, Web of Knowledge, Scopus, Google Scholar, and LILACs) was performed to identify all peer-reviewed papers reporting data regarding the evaluation of children's and adolescents' perceptions of dental esthetic factors. The search was conducted using a research strategy based on keywords such as "children," "adolescents," "smile aesthetics perception," "smile aesthetics evaluation." Studies analyzing smile esthetics involving at least 10 observers younger than 18 years of age were selected. RESULTS: Among the 1667 analyzed articles, five studies were selected for the final review process. No study included in the review analyzed perception of smile anomalies in a quantitative or qualitative way, thus no threshold was identified for smile features. Among the analyzed samples, unaltered smiles were always significantly associated with better evaluation scores when compared with altered smiles. CONCLUSIONS: Smile esthetics influence social perception during childhood and adolescence. However, thresholds of smile esthetic acceptance in children and adolescents are still not available.

Effects of therapy on masseter activity and chewing kinematics in patients with unilateral posterior crossbite.

OBJECTIVE: To describe the effects of therapy on masseter activity and chewing kinematic in patients with unilateral posterior crossbite (UPC). DESIGN: Fifty children (age: mean ± SD: 9.1 ± 2.3 years) with UPC (34 on the right side, 16 on the left side) and twenty children (age: 9.5 ± 2.6 years) with normal occlusion were selected for the study. The mandibular motion and the muscular activity during chewing soft and hard boli were simultaneously recorded, before and after correction with function generating bite, after a mean treatment time of 7.3 ± 2.4 months plus the retention time of 5-6 months. The percentage of reverse cycles and the percent difference between ipsilateral and contralateral peaks of the masseter electromyography envelopes were computed. RESULTS: Before therapy, the percentage of reverse cycles during chewing on the crossbite side was greater in patients than in controls (P<0.001) and significantly reduced after therapy (P<0.001) towards the reference normal value (soft bolus; pre: 57 ± 30%, post:12 ± 17%; hard bolus; pre: 65 ± 34%, post: 12 ± 13%; reference value: soft bolus 4 ± 2%, hard bolus 5 ± 3%). Before therapy the percent difference between electromyography envelope peaks in patients was lower than in controls (P<0.01) and significantly increased after therapy (P<0.05) becoming similar to the reference normal value. CONCLUSIONS: The correction induced a normal-like coordination of masseter muscles activity together with a significant reduction of the reverse chewing patterns. The previous altered muscular activation corresponded to the altered kinematics of reverse chewing cycles that might be considered a useful indicator of the severity of the masticatory function involvement.

Diagnostic accuracy and measurement sensitivity of digital models for orthodontic purposes: A systematic review.

INTRODUCTION: Our objective was to assess the accuracy, validity, and reliability of measurements obtained from virtual dental study models compared with those obtained from plaster models. METHODS: PubMed, PubMed Central, National Library of Medicine Medline, Embase, Cochrane Central Register of Controlled Clinical trials, Web of Knowledge, Scopus, Google Scholar, and LILACs were searched from January 2000 to November 2014. A grading system described by the Swedish Council on Technology Assessment in Health Care and the Cochrane tool for risk of bias assessment were used to rate the methodologic quality of the articles. RESULTS: Thirty-five relevant articles were selected. The methodologic quality was high. No significant differences were observed for most of the studies in all the measured parameters, with the exception of the American Board of Orthodontics Objective Grading System. CONCLUSIONS: Digital models are as reliable as traditional plaster models, with high accuracy, reliability, and reproducibility. Landmark identification, rather than the measuring device or the software, appears to be the greatest limitation. Furthermore, with their advantages in terms of cost, time, and space required, digital models could be considered the new gold standard in current practice.

Psycho-Neurological Status in Children with Malocclusions and Muscle Pressure Habits.

Non-nutritive sucking behaviors such as finger- and tongue-sucking, tongue thrust, lips- or cheek-sucking, nail-, lip- or tongue-biting and other pressure habits represent risk factors for malocclusion. The association between psycho-neurological disorders and different types of malocclusion in children with sucking habits was long studied. During neurological examination, many children with sucking habits are diagnosed as Minimal Cerebral Dysfunction or Attention Deficit Hyperactivity Disorder (ADHD) bearers. The aim of this study is to assess the psycho-neurological status and motor disorders in children with malocclusion and normal occlusion. 135 children, aged between 8 and 12 years old, were examined, 42 children with normal occlusion and 93 children with different types of malocclusion. Besides clinical examination, all children were studied by the following psychoneurological methods: 1) Parent's Questionnaire, 2) Diagnostic interview Kiddie-Sads 3) Physical and Neurological Exam for Subtle Signs and 4) stabilometric tests. This study shows as in presence of dentofacial anomalies, pressure habits, ADHD reports significant effects on the functional state of the motor system: increases are noted in all basic parameters of statokinesiograms (crossed distance, sway area and ellipse surface), which lead to increased physiologic energy costs to maintain the vertical position of the body.

Efficacy of surgical and non-surgical interventions on accelerating orthodontic tooth movement: a systematic review.

PURPOSE: To conduct a systematic review of randomised controlled trials (RCTs) evaluating the effect of surgical and non-surgical procedures on the acceleration of orthodontic tooth movement (OTM) as an adjunct to orthodontic therapy (OT) in order to estimate the efficacy of these procedures and the benefit of their use in everyday orthodontic practice. MATERIALS AND METHODS: Literature search was performed on PubMed, Scopus, Web of Science and Cochrane databases up to July 2014. Inclusion criteria were: (1) RCTs; (2) orthodontic therapy on permanent dentition; (3) application of adjunctive surgical or non-surgical procedures for accelerating OTM; (4) measurement of tooth movement. The primary outcome measure was tooth movement expressed as cumulative tooth movement (CTM), rate of tooth movement (RTM) or time of tooth movement (TTM). Pain and discomfort, periodontal health, anchorage loss, bone and root changes, and undesired tooth movement were evaluated as secondary outcomes. RESULTS: Literature research identified 184 studies. After screening of titles, abstracts and full-text studies, fifteen fulfilled the inclusion criteria and were included in this review. Six of the included studies investigated the effect of corticotomies, one of interseptal bone reduction, four of lowlevel laser therapy (LLLT), three of intraoral/extraoral devices releasing extracorporeal shock waves (ESWT), pulsed electromagnetic field (PEMF) and electrical current, respectively, and one of injected substances (relaxin) as an adjunct to OT. Three studies resulted of high methodological quality, six of medium, and six of low quality. Interseptal bone reduction was reported to increase RTM during the first 2 months (P = 0.002) and CTM at 3 months (P = 0.003). Studies investigating corticotomy reported significantly increased RTM (up to 2.3 times) during the first months after intervention, whereas results on TTM and CTM were quite controversial ranging from non-significant to highly significant (up to three times of TTM increase). The heterogeneity between studies investigating corticotomy could not allow for quantitative synthesis of the findings. Out of four studies investigating LLLT three reported positive effect on OT. Due to inadequate statistical analysis of data from original articles, results could not be summarised in meta-analyses. Effects of both electrical current devices and PEMF devices on CTM were reported to be larger on the experimental sides than on the control sides (P < 0.001). The other interventions were reported to be of no statistical or clinical relevance. CONCLUSIONS: In the short term, corticotomy can accelerate OTM whereas long-term effects are questionable, thus no firm conclusions can be made on its efficacy and benefit of clinical use. There is some evidence that LLLT can slightly accelerate OTM but this result is not significant and the effect estimated is not clinically relevant. The very limited research-based evidence suggesting beneficial effects of interseptal bone reduction, electrical current and PEMF on OTM does not allow for solid conclusions. More high quality clinical research is required in order to estimate the efficacy of adjunctive interventions on accelerating OTM and their potential clinical use.

Periodontal health during clear aligners treatment: a systematic review.

BACKGROUND: Clear aligner treatment (CAT) has been cited as a safe and comfortable orthodontic procedure for adult patients. However, the available evidence is scarce. OBJECTIVE: To perform a systematic review of the existing literature in order to assess periodontal health during CAT. SEARCH METHODS AND SELECTION CRITERIA: Pubmed, Pubmed Central, National Library of Medicine's Medline, Embase, Cochrane Central Register of Controlled Clinical trials, Web of Knowledge, Scopus, Google Scholar, and LILACS were searched from January 1945 to September 2014 to identify all peer-reviewed papers potentially relevant to the review. DATA COLLECTION AND ANALYSIS: After duplicate selection and extraction procedures, the risk of bias was assessed according to the Centre for Reviews and Dissemination criteria, and a 3-point grading system, as described by the Swedish Council on Technology Assessment in Health Care (SBU), was used to rate the methodological quality of the selected papers. A PICOS table was used for data extraction. RESULTS: Five relevant articles were selected from the 1247 identified articles. The level of evidence was moderate for all the studies. A significant improvement of the periodontal health indexes was revealed, in particular when CAT was compared to fixed appliances. No periodontal CAT adverse effects were observed in the selected studies. CONCLUSIONS: Periodontal health indexes were significantly improved during CAT. The results of this review should be interpreted with some caution because of the number, quality, and heterogeneity of the included studies.

Efficacy of clear aligners in controlling orthodontic tooth movement: a systematic review.

OBJECTIVE: To assess the scientific evidence related to the efficacy of clear aligner treatment (CAT) in controlling orthodontic tooth movement. MATERIALS AND METHODS: PubMed, PMC, NLM, Embase, Cochrane Central Register of Controlled Clinical Trials, Web of Knowledge, Scopus, Google Scholar, and LILACs were searched from January 2000 to June 2014 to identify all peer-reviewed articles potentially relevant to the review. Methodological shortcomings were highlighted and the quality of the studies was ranked using the Cochrane Tool for Risk of Bias Assessment. RESULTS: Eleven relevant articles were selected (two Randomized Clinical Trials (RCT), five prospective non-randomized, four retrospective non-randomized), and the risk of bias was moderate for six studies and unclear for the others. The amount of mean intrusion reported was 0.72 mm. Extrusion was the most difficult movement to control (30% of accuracy), followed by rotation. Upper molar distalization revealed the highest predictability (88%) when a bodily movement of at least 1.5 mm was prescribed. A decrease of the Little's Index (mandibular arch: 5 mm; maxillary arch: 4 mm) was observed in aligning arches. CONCLUSIONS: CAT aligns and levels the arches; it is effective in controlling anterior intrusion but not anterior extrusion; it is effective in controlling posterior buccolingual inclination but not anterior buccolingual inclination; it is effective in controlling upper molar bodily movements of about 1.5 mm; and it is not effective in controlling rotation of rounded teeth in particular. However, the results of this review should be interpreted with caution because of the number, quality, and heterogeneity of the studies.

Effectiveness of a fixed anterior bite plane in Class II deep-bite patients.

Orthodontic treatment of patients with distoclusion combined with dental deep bite and linguo version of the front upper teeth is one of the most difficult forms of malocclusion to treat to a functional and morphological optimum. Our objective was to analyze the efficacy of a fixed anterior bite plane appliance to disclude the teeth and correct this type of malocclusion. At the Department of Orthodontics MSUMD (Moscow State University of Medicine and Dentistry), we proposed the use of a fixed anterior bite plane for the effective treatment of patients with distoclusion combined to a dental deep bite. This appliance was used in 35 patients aged 11 to 15 years (13.2 +/- 1.2) with distoclusion combined with deep bite in a therapeutical approach that also involved an osteopathic correction. The appliance permitted the correction of the distoclusion by discluding the posterior teeth, allowing eruption of the molars and premolars which improved the occlusal plane line (Curve of Spee) and changed the inclination of the upper incisors which liberated the mandible from its retruded position. We also noted an effect on the postural status of the patient.

Reliability of a portable device for the detection of sleep bruxism.

OBJECTIVES: The aim of the study was to assess the repeatability in detecting sleep bruxism (SB) episodes by combined surface electromyography and heart rate (HR) signals recorded by a compact portable device (Bruxoff®). SB episodes are preceded by a sudden HR change. Thus, HR detection increases the precision of automatic detection of SB. MATERIALS AND METHODS: Ten healthy subjects (five women and five men; 30.2 ± 11.02 years) were selected for the study. Rhythmic masseter muscle activities, constituting the basic pattern of SB, were detected during three nights of recording during three different weeks with the Bruxoff device. RESULTS: The two-way ANOVA was not significant for SB episodes per night, SB episodes per hour, and heart frequency: no significant differences were observed during the three different nights of recording for each of the abovementioned variables (P > 0.05). The intraclass correlation coefficient showed a good reproducibility for SB episodes per night (69 %), SB per hour (74 %), and heart frequency (82 %). A poor reproducibility was revealed for the number of masseter contractions (53 %). The Pearson analysis showed the absence of a significant correlation between the number of masseter contractions per night and the number of SB episodes per night (r = -0.02, P = 0.91). CONCLUSIONS: The Bruxoff device showed a good reproducibility of measurements of sleep bruxism episodes over time. CLINICAL RELEVANCE: These findings are important in the light of the need for simple and reliable portable devices for the diagnosis of SB both in the clinical and research settings.

Alexithymia, anger and psychological distress in patients with myofascial pain: a case-control study.

AIMS: The aim of this study was to investigate psychological distress, anger and alexithymia in a group of patients affected by myofascial pain (MP) in the facial region. METHODS: 45 MP patients [mean (SD) age: 38.9 (11.6)] and 45 female healthy controls [mean (SD) age: 37.8 (13.7)] were assessed medically and psychologically. The medically evaluation consisted of muscle palpation of the pericranial and cervical muscles. The psychological evaluation included the assessment of depression (Beck Depression Inventory-short form), anxiety [State-Trait Anxiety Inventory Form Y (STAI-Y)], emotional distress [Distress Thermometer (DT)], anger [State-Trait Anger Expression Inventory-2 (STAXI-2)], and alexithymia [Toronto Alexithymia Scale (TAS)]. RESULTS: the MP patients showed significantly higher scores in the depression, anxiety and emotional distress inventories. With regard to anger, only the Anger Expression-In scale showed a significant difference between the groups, with higher scores for the MP patients. In addition, the MP patients showed significantly higher alexithymic scores, in particular in the Difficulty in identifying feelings (F1) subscale of the TAS-20. Alexithymia was positively correlated with the Anger Expression-In scale. Both anger and alexithymia showed significant positive correlations with anxiety scores, but only anger was positively correlated with depression. CONCLUSION: A higher prevalence of depressive and anxiety symptoms associated with a higher prevalence of alexithymia and expression-in modality to cope with anger was found in the MP patients. Because the presence of such psychological aspects could contribute to generate or exacerbate the suffering of these patients, our results highlight the need to include accurate investigation of psychological aspects in MP patients in normal clinical practice in order to allow clinicians to carry out more efficacious management and treatment strategies.

Assessment of the reliability and repeatability of landmarks using 3-D cephalometric software.

The aim of this study was to analyze the reliability and repeatability of identification landmarks using 3-D cephalometric software. Ten orthognathic patients were selected for this study and underwent the following protocol: 1. radiographic evaluation (CBCT technique); 2. stone casts; 3. photos; and 4. 3-D cephalometric evaluation. Twenty-one hard tissue landmarks and 14 cephalometric measurements were taken three times (T1, T2, and T3) on each patient, with an interval of one week by two experts in orthodontics (A, B). Standard deviation and Pearson's correlation coefficient were calculated to evaluate intra- and inter-observer repeatability. The results showed a strong correlation for both intra- and inter-observer Pearson's correlation coefficient (>0.7). The current preliminary study showed that the reliability and repeatability of the identification landmarks were very high if the 3-D cephalometric landmarks are defined correctly in the three planes of the space. Further evaluation is necessary to better define the 3-D cephalometric system.

Chewing pattern and muscular activation in open bite patients.

Different studies have indicated, in open bite patients, that masticatory muscles tend to generate a small maximum bite force and to show a reduced cross-sectional area with a lower EMG activity. The aim of this study was to evaluate the kinematics parameters of the chewing cycles and the activation of masseters and anterior temporalis muscles of patients with anterior dental open bite malocclusion. There have been no previous reports evaluating both kinematic values and EMG activity of patients with anterior open bite during chewing. Fifty-two young patients (23 boys and 29 girls; mean age±SD 11.5±1.2 and 10.2±1.6years, respectively) with anterior open bite malocclusion and 21 subjects with normal occlusion were selected for the study. Kinematics parameters and surface electromyography (EMG) were simultaneously recorded during chewing a hard bolus with a kinesiograph K7-I Myotronics-Usa. The results showed a statistically significant difference between the open bite patients and the control group for a narrower chewing pattern, a shorter total and closing duration of the chewing pattern, a lower peak of both the anterior temporalis and the masseter of the bolus side. In this study, it has been observed that open bite patients, lacking the inputs from the anterior guidance, that are considered important information for establishing the motor scheme of the chewing pattern, show narrower chewing pattern, shorter lasting chewing cycles and lower muscular activation with respect to the control group.

Clinical and instrumental evaluation of the temporomandibular joint before and after surgical correction of asymptomatic skeletal class III patients.

The purpose of this prospective study was to evaluate the temporomandibular joint (TMJ) morphology, the disk position, and the TMJ symptoms before and after surgical-orthodontic correction of skeletal class III malocclusion.Eleven adult patients were recruited to participate in this longitudinal study. Each patient received presurgical and postsurgical orthodontic treatment with fixed appliances. Six patients were corrected exclusively through mandibular setback, whereas 5 received combined mandibular setback and maxillary advancement. All patients were investigated before and 2 years after treatment through (1) clinical examination, (2) magnetic resonance imaging, and (3) Computerized axiography (CA).The incidence of clinical signs and symptoms was reduced 2 years after surgical-orthodontic treatment, the condyle-disk relationship and TMJ appearance at magnetic resonance imaging were unchanged, and CA showed a significant improvement of TMJ border movements.Mandibular setback surgery does not appear to alter the condyle-disk relationship, whereas correction of class III malocclusion seems to improve clinical and CA signs of TMJ function. Further controls and more long-term evaluation of these patients are necessary to assess the maintenance of these improvements in time.

Slow or rapid palatal expansion for early treatment of unilateral posterior crossbite? Evaluation of the reverse chewing cycles correction.

OBJECTIVES: It is well established that patients with a unilateral posterior crossbite, when chewing on the affected side, show an increased frequency of reverse chewing cycles. It was hypothesized that the correction of reverse cycles may be due to the characteristics of the therapy. The aim was to investigate the prevalence of reverse chewing patterns in children with unilateral posterior crossbite before and after treatment with Function Generating Bite (FGB). MATERIALS AND METHODS: Twenty children, (9 boys, 11 girls; age, mean ± SD, 7.5 ± 1.1), 10 with a right and 10 with a left posterior unilateral crossbite were selected. Mandibular movements during chewing soft and hard boluses were measured with a kinesiograph (K7 -I, Myotronics Inc. Tukwila, Washington, USA). RESULTS: The results showed a significant difference when comparing the percentage of reverse chewing patterns, before and after therapy with FGB, during chewing on the crossbite side both with soft and hard bolus (p<0.0001). No significant differences were observed during chewing on the non-crossbite side. DISCUSSION: The results of this study confirmed that FGB corrects both the dental and functional asymmetries. Knowing that the rapid palatal expansion does not correct the masticatory function, it is of clinical relevance, for the orthodontists, the knowledge and the understanding of the functional outcomes with different therapies. CONCLUSIONS: The type of treatment and the biomechanics of the appliance used are of great importance for the correction of the reverse chewing cycles and for rebalancing the functional asymmetry of children with unilateral posterior crossbite.

Evaluation of the stomatognathic system in patients with rheumatoid arthritis according to the research diagnostic criteria for temporomandibular disorders.

The aim of this study was to investigate the clinical features of stomatognathic dysfunction in patients with rheumatoid arthritis (RA). The study sample consisted of 40 patients with RA (34 female, 6 male), mean age 44 years, recruited at the Rheumatology Division of the Department of Internal Medicine, University of Pisa, Italy. The inclusion criteria were diagnosis of RA according to the criteria of the American Rheumatism Association (ARA). In the study, 82.5% (n=33) of patients affected by RA satisfied at least the criteria of one diagnosis of temporomandibular disorders (TMD), according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The results are in agreement with the literature and the prevalence of such involvement ranges between 53% and 94% of patients. Several studies reported an involvement of the stomatognathic system in RA. In fact, RA can affect the temporomandibular joint as much as any other synovial joint. A more thorough analysis is required for a multidisciplinary approach to gnathological patients, including assessment by a rheumatologist. This issue and its epidemiologic relevance need further scientific research. Dentistry has a fundamental role in this process since patients who present with a systemic disease such as RA can be recognized and intercepted and referred to medical specialists, i.e., rheumatologists, to provide a diagnosis and therapy.

Temporomandibular joint disorders during HIV infection: a case report.

Temporomandibular disorders (TMD) is a term reflecting chronic, painful, craniofacial conditions usually of unclear etiology with impaired jaw function. Human immunodeficiency virus (HIV)-infected patients often report chronic pain and pathologies targeting body joints during retroviral therapy. Although both conditions may share similar secondary disorders, no conclusive cause-effect relationship has been found linking the TMD to the HIV-antiviral treatment. This report describes a case of TMD associated with HIV infection during active retroviral therapy. Clinicians should be aware that treatment of an HIV-infected patient with TMD requires an interdisciplinary team approach.

Interleukin-1 gene cluster polymorphisms and gingival recessions after orthodontic treatment.

INTRODUCTION: Genetic polymorphisms in the interleukin-1 gene cluster have been associated with the severity of periodontal diseases featured by a variable degree of destruction of connective tissue and bone, such as periodontitis and periimplantitis. This study was aimed to investigate if a link exists between such interleukin-1 gene polymorphisms and the development of gingival recessions during orthodontic treatment in Italian children. METHODS: We evaluated, in 74 young Italian patients of both sexes, the -889 C/T polymorphism of the interleukin-1alpha gene and the -511 C/T and +3954 C/T polymorphisms of interleukin-1alpha gene by polymerase chain reactions-restriction fragment length polymorphism method using NcoI, AvaI and TaqI as restriction enzymes. RESULTS: No association of interleukin-1 genotypes investigated and gingival recession occurring during orthodontic treatment were identified. CONCLUSION: In the population studied specific interleukin-1 genotypes (linked to a higher susceptibility to bone resorption in periodontal disease) there does not appear to be any association with the development of gingival recessions during orthodontic treatment.

The orthodontic treatment of TMD patients: EMG effects of a functional appliance.

The aim of this work was to test the effects of the Function Generator Bite (FGB) on the masticatory muscles of temporomandibular joint dysfunction (TMD) subjects. Two groups were selected for the study. A group of 20 TMD patients (group F) requiring orthodontic treatment and treated with FGB and a group of 10 healthy subjects (group H) were considered. Both groups were evaluated before the therapy began (TO) and then after 18 months of therapy (T1). An electromyographic analysis of the masseter and temporalis anterior muscles and a clinical evaluation according to the Research Diagnostic Criteria for TMD (RDC/TMD) were performed. A statistical difference between the two groups was observed at TO with respect to the activity index. TMD subjects showed a lower value of the index. Further studies are necessary to fully understand the utility of this EMG index as a diagnostic indicator.