A patient with severely anterior cross bite during the growth period treated with a myofunctional training device

Although functional jaw orthopedic appliances have been used to treat anterior cross bite during the growth and development period, its functional effect for severely anterior cross bite has not been clarified. Cases treated with a myofunctional training device for deciduous tooth anterior cross bite have been reported, but normally, these devices are not used to improve occlusion of patients with severly anterior cross bite. The patient was an 8-year and 4-month-old boy with Skeletal 3 anterior cross bite, Terminal plane Mesial step type with -3 mm over jet and +6 mm over bite, and ANB of -3.0° and U1 to SN of 86°. We proposed the conventional treatment method, but active treatment was rejected due to various background factors, and consent could not be obtained. Thus, we proposed the use of a myofunctional training device and consent was obtained. The attached device guided the abnormal pressure of various muscles of the oral cavity in an appropriate direction and promoted forward development of the upper jaw. ANB improved to +1.0°, curvature of Spee was flattened, and labial inclination of the upper teeth and inferior backward growth of the mandible were observed, which improved coverage of the upper tooth region that the patient most strongly desired