This study to assessed the prevalence of signs and symptoms of temporomandibular disorders (TMD) by means of the frequency distribution of data for 218 dentistry students from a Brazilian public university using the Fonseca's questionnaire. The group consisted of 96 men and 122 women, with an average age of 20 years. Of the students, 53.21% showed some level of TMD: 35.78% mild TMD 11.93% moderate and 5.5% severe. Women were the most affected group, with 63.11% showing some level of TMD, against 40.62% of men. When considering only severe TMD, women are approximately 9 times more affected than men. Students with any level of TMD showed marked characteristics: 76.72% considered themselves tense people; 71.55% reported to clench or grind their teeth; 65.52% reported clicking of the temporomandibular joint; 64.66% reported frequent headache and 61.21% neck pain. In conclusion, clinical signs and symptoms of TMD can occur in young population and this information is of great importance for the early diagnosis of the dysfunction.

summary  The purpose of this study is to evaluate the interocclusal appliance efficiency in patients with temporomandibular disorder (TMD), by using computerized electromyographic (EMG) evaluation in the rest position of the mandible. Twenty‐two patients (male and female) with TMD symptoms, between 18 and 53 years of age, were examined. EMG evaluations were performed before the treatment and during the 90th, 120th and 150th day of using the interocclusal appliance therapy. In the 90th and 120th day, inserting canine guidance and group function disclusion, respectively, changed interocclusal appliance. The results showed that group function disclusion caused shorter EMG activity in the mandible rest position for the anterior temporalis muscle.

It could be concluded that the elderly show hyperactivity of masticatory musculature during posture maintenance and a slight hypoactivity of this musculature during chewing when analysed side by side with young individuals.

No abstract

The function and the level of activity of the orbicularis oris (upper and lower), and of the mentalis muscles were verified electromyographically in resting position and in several movements and carried out in 18 children aged 8-12 years, divided into three groups: one with normal occlusion, and two with Class II division 1, with atypical swallowing and/or incompetent lips, who had received no orthodontic treatment. It was observed that, in a resting position with the lips separated, there was no activity in any of the muscles. When there was a contact of the lips, action potentials were recorded in the muscles studied, in those individuals with incompetent lips. In the movements of sucking either through a straw or a pacifier and the thumb, there were no differences among the groups. The incompetent lips group presented very marked muscle activity of the lower orbicularis oris and mentalis in the movement of sucking a lollipop. In deglutition of saliva, the orbicularis oris presented slight activity, and the mentalis, moderate. In deglutition of water, the mentalis presented very marked activity, whereas, the upper and lower orbicularis oris presented moderate and marked activities, respectively.

The electromyographic (EMG) examination of 11 normal individuals in whom bipolar fine-wire indwelling electrodes were placed showed no EMG activity during rest periods and only very slight to slight activity during normal oral functionsmduring aberrant oral activity, such as thumb-sucking, the orbicularis oris and genioglossus muscles gave a marked EMG response and the buccinator muscles were slightly active. These findings may help explain the classical malocclusions seen in tongue-thrusters and thumb-suckers.

Using bipolar fine-wire electrodes, we examined the right and left longus colli (LC ) and sternocleidomastoideus ( StM) muscles electromyographically in ten healthy young adults. Action potentials were recorded on FM magnetic tape and each experiment was also videotaped. The head-neck motions were recorded using a special neck goniometer. The muscles were studied in sitting, supine, prone and lateral positions, both during free movements and against resistance. There was complete inactivity in both muscles in relaxed sitting, normal breathing, deep expiration, and wet and dry swallowing. There was very marked synchronous EMG activity of the LC and StM muscles during resisted forward flexion, marked activity during neck flexion against head weight in the supine position, and during resisted right and left side-bending. Variable activity was found in both muscles during deep breathing, coughing, forceful blowing, loading on top of the head, resisted backward extension, neck holding against head weight in the prone position and in twisting movements downwards and upwards. During free flexion-extension movements, LC and StM act synchronously. During free lateral bending they work homolaterally, but during free rotation to the right, the right LC works with the left StM and vice versa.

The functions of the normal semispinalis capitis and splenius capitis muscles of fifteen subjects were evaluated electromyographically with bipolar fine-wire electrodes. The voltage-output data were integrated and analyzed by computer and showed that the main function of semispinalis capitis is limited to extension of the head. However, splenius capitis both extends the head and rotates it to its own side.The posterior cervical muscles can be divided into four layers. The first layer is formed by the trapezius muscle which is concerned with the movements of the upper limb and the shoulder. The second and the third layers are mainly formed by splenius and semispinalis muscles respectively, and the fourth layer is formed by small muscles which are seen between the occipital bone and the first two cervical vertebrae. Among these muscles the semispinalis capitis and the splenius capitis are considered to have an important role in the movements of the head and neck because of their anatomical situation and their dimensions. But only one early report is available on the role of the muscles studied electromyographically (Tournay and Paillard, '52). Modern fine-wire electrode techniques and computer analysis of the myopotentials permitted us to analyze their exact functions in a series of normal volunteers. MATERIALS AND METHODSUsing bipolar fine-wire electrodes (Basmajian and Stecko, '62) we recorded the electromyographic activity of both right and left semispinalis capitis and splenius capitis muscles simultaneously in fifteen healthy adults (ten males and five females) who have no history of neck injury. Their ages ranged from twenty-one to fifty. We determined the exact ideal location and depth for the electrodes by means of preliminary tests in the dissecting room. Thus the electrodes were inserted into the semispinalis capitis 2 cm below the occipital bone and 2 cm lateral from the midline, and into the splenius capitis about 3 cm below the mastoid process and 3 cm lateral from the mid-line.Action potentials were amplified and recorded on FM magnetic tape and both movements and muscle activity were videotaped simultaneously for later validation of results, The EMG data were analyzed by a PDP-8 Computer programmed to integrate the voltage output and to normalize (or compare it on a percentage basis) with standards of maximum (100% ) activity for the muscles individually over the total time of a movement. The muscles were studied according to a set protocol in the resting position and in a variety of movements of the neck and head, each lasting five seconds.Final grading of the EMG for the purpose of making the numerical data meaningful to readers is on the basis of: 0, inactive (less than 1% ); -, negligible (1-5% ); -t, slight (6-1596 ); 2 +, moderate (16-50% ); 3 +,marked (51-100% ).