OBJECTIVETo investigate the changes in electromyographic activities of the temporal and masseter muscles at different positions of the mandible.

METHODSTwenty orthodontic patients with Angle Class II malocclusion and mandibular retrusion (ANB<6°) aged 10-14 years were enrolled in this study. All the patients were treated with Forsus fixed functional appliance combined with MBT straight-wire appliance. The electromyographic activities of the temporal (T) and masseter (M) muscles before, during and after functional treatment were evaluated by assessing the average integrated electromyogram (EMG) and T/M ratio at clenching status in different mandibular positions.

RESULTSAfter functional forward positioning of the mandible, the electromyographic activities of the temporal and masseter muscles decreased and T/M ratio increased significance at the clenching status (P<0.05).

CONCLUSIONThe appliance insertion and activation is associated with a decreased EMG activity of the temporal and masseter muscles, and the T/M ratio is correlated to the position of the mandible.

Adolescent ; Child ; Electromyography ; Female ; Humans ; Male ; Malocclusion, Angle Class II ; physiopathology ; therapy ; Masseter Muscle ; physiopathology ; Orthodontic Appliances ; Retrognathia ; physiopathology ; Temporal Muscle ; physiopathology

Anterior disc displacement is a common subtype seen in temporomandibular disorders (TMD) patients. It may cause mandibular movement disorders, such as clicking of joint, intermittent closed lock, limitation of mouth opening, etc. These disorders may affect the life qualities of patients. Anterior disc displacement may also cause mandibular malformations, especially among adolescents, which may affect the growth of condyle, therefore may have a correlation with mandibular retrusion or mandibular deviation when grown up. This paper going to review the influences of anterior disc displacement on oral mandibular function and morphology and their biological mechanisms.
Adolescent ; Humans ; Mandible ; abnormalities ; pathology ; Mandibular Condyle ; growth & development ; Mandibular Diseases ; etiology ; Movement ; Retrognathia ; etiology ; Temporomandibular Joint Disorders ; etiology ; physiopathology

There are little information on prevalence of obstructive sleep apnea syndrome (OSAS) and clinical features in the young military population. The purpose of this study was to estimate the prevalence of snoring and high risk of OSAS in young male soldiers in Korea and to identify the risk factors of OSAS. A total of 665 participants (aged 20-23 yr) who visited the Armed Forces Ildong Hospital for regular physical examination were enrolled. All participants completed the Berlin Questionnaire and underwent a physical examination. The participants with high risk for OSAS completed portable sleep monitoring. The prevalence of snoring and high risk of OSAS in young male soldiers in Korea was 13.5% and 8.1%, respectively. The prevalence of high arched palate, tongue indentation, long uvula, large tonsil and retrognathia was significantly higher in the high risk OSAS group. High arched palate, long uvula or low lying soft palate, tonsil size III or IV, Epworth Sleepiness Scale score > 10 and obesity (BMI > 27 kg/m2) were found to independently predict OSAS. For early identification and treatment of young soldiers with OSAS in a military environment, a precise screening by questionnaire and physical examination is needed.
Asian Continental Ancestry Group ; Body Mass Index ; Humans ; Logistic Models ; Male ; *Military Personnel ; Odds Ratio ; Palate/anatomy & histology ; Palatine Tonsil/anatomy & histology ; Polysomnography ; Prevalence ; Questionnaires ; Republic of Korea ; Retrognathia/physiopathology ; Risk Factors ; Sleep Apnea, Obstructive/*epidemiology ; Snoring/epidemiology ; Uvula/anatomy & histology ; Young Adult