Orthodontic treatment of a patient with hypoglossia.

OBJECTIVE: The aim of this case study was to provide a detailed report of the orthodontic approach used in treating a Japanese patient with congenital hypoglossia. PATIENT: The patient was a 6-year-old girl with hypoglossia, micrognathia, congenital absence of three incisors, and a telescopic occlusion accompanied by an extremely narrow lower arch. She had no limb anomalies, and her speech was normal. RESULTS: Bite opening and mandibular widening from the early mixed dentition dramatically improved the extremely constricted mandible and telescopic occlusion. Cephalometric tracings taken from the beginning to the end of active treatment revealed substantial forward and downward growth in the mandible over time, which may have contributed to correction of the intermaxillary relationship. CONCLUSIONS: Treatment of telescopic occlusion by bite opening and mandibular widening from the early mixed dentition may be effective in facilitating mandibular growth acceleration. An acceptable intermaxillary occlusal relationship and improvement of profile were achieved by an orthodontic approach in this case.

Effects of cortical activations on enhancement of handgrip force during teeth clenching: an fMRI study.

We assessed the effect of teeth clenching on handgrip force behaviorally, and investigated cortical activity during the occurrence of facilitatory effects using functional magnetic resonance imaging (fMRI). Twenty-three participants were assessed as to whether they had habitual teeth clenching during maximal voluntary contraction (MVC) exertion, and 21 of them were identified to have such a habit. For those participants, behavioral testing showed that MVC with clenching was greater compared with without clenching (approximately 108% greater on average). Next, cortical activity was measured under gripping with clenching (GwC), gripping without clenching (GwoC), and teeth clenching (C) conditions. We found that the activity of the hand region in primary motor cortex (M1), cingulate motor area/supplementary motor area (CMA/SMA) and anterior cerebellum (AC) was greater in contrast of GwC vs. (GwoC+C). Furthermore, significant correlation was observed between the increasing ratio of the handgrip force and the % signal change in the hand region of M1 and AC, but not in CMA/SMA. These results suggest that the activation in the hand region of M1 and AC may facilitate the spinal motoneurons, and the activation in the hand region in M1 by clenching may be due to a signal from CMA/SMA.