An adolescent case of anterior open bite with masticatory muscle dysfunction.

In adolescence an open bite is likely to be induced by various causes, and most patients with open bite show masticatory muscle dysfunction. The orthodontic correction of an open bite may lead to the recovery of harmonious stomatognathic function. This article reports treatment for a 12-year and 10-month-old female patient with an anterior open bite. She complained of occlusal disturbances due to an anterior open bite. Before the eruption of the upper second molars, she recognized the presence of occlusal contacts between the upper and lower anterior teeth. Before treatment, the activity of the masticatory muscles was relatively low during clenching. An upper lingual arch with an accessory spring to eliminate the premature contact and to improve the anterior open bite plus conventional fixed appliances for tooth alignment was selected as the treatment plan. Immediately after improvement of the open bite, the muscle activity became slightly greater than that at the initial stage. The total treatment time was 13 months. After treatment, an acceptable occlusion was achieved, the masticatory muscles were working harmoniously, and their activity was much higher than that at the initial stage. After a 2-year retention period, an acceptable occlusion was maintained without recurrence of the open bite, indicating a long-term stability of occlusion. The result of this treatment indicated that correction of open bite is of great importance for prevention of skeletal impairment and recovery of harmonious stomatognathic function lost by an unstable occlusion.