Purpose: There is little information available regarding swallowing tongue dynamics in cases that show remarkable discordance in the relationship between the upper and lower jaws. In this study, we measured the tongue motion during swallowing by ultrasonography in patients with mandibular prognathism and compared them with volunteers with normal occlusion.
Methods: The subject group comprised 10 patients with mandibular prognathism （6 males, 4 females）. Ten volunteers with normal occlusion （2 males, 8 females） served as controls. The subjects were instructed to swallow about 4ml of tasteless jelly, and the tongue movement during swallowing was measured by ultrasonography. We measured the following times on the M-mode waveform in the center of the tongue, “Duration of grooving formation （T1）”, “Duration of grooving disappearance （T2）”, “Duration from grooving disappearance until tongue-palate contact （T3）”, “Duration of tongue-palate contact （T4）”, “Duration of return to rest （T5）” and “Total swallowing duration （T6）”. In the periphery of the tongue, we measured “Total swallowing duration （T7）” and qualitatively assessed the tongue waveform as well.
Results: In the center of the tongue, T3, T5 and T6 were significantly longer in the subject group than in the control group. In the periphery of the tongue, T7 was also significantly longer in the subject group than in the control group. The tongue position of patients with mandibular prognathism tends to be low, so a longer time was necessary to lift the tongue to the palate and the anchoring effect of the contact between the tip of the tongue and the anterior palate became weak. Due to this, a longer swallowing time at the periphery of the tongue was possibly needed in the subject group. Further, the type of tongue movement seems to have been specialized because of frequent up-and-down movement of the tongue during swallowing.
Conclusions: The present findings suggest that patients with mandibular prognathism, due to their morphological disharmony, need excessive time to lift the tongue surface to the palate, resulting in a longer swallowing time at the periphery of the tongue as well as a specialized tongue movement.

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Purpose: Previous studies on masticatory function in patients with mandibular prognathism have examined various aspects such as occlusal contact area, mandibular movement, and masticatory muscle activity. However, there have been few reports on the relationship between objective masticatory performance and craniofacial morphology in patients with mandibular prognathism due to the lack of a quick and simple method. This study aimed to clarify the relationship between masticatory performance and craniofacial morphology for patients with mandibular prognathism by using a fully automatic system.
Subjects and Methods: Ten patients with mandibular prognathism （age: 16.6±1.3 years） and 10 volunteers with individual normal occlusion （age: 24.1±2.6 years） as controls were enrolled in this study. At the initial examination, lateral cephalograms were taken and analyzed. Masticatory performance was assessed by a fully automatic measuring system （Tokyo-koden, Tokyo, Japan） using a testing gummy jelly （UHA-Mikakuto, Osaka, Japan）. Chewing time was measured with a stopwatch. Occlusal contact area was measured using a silicone testing material and analyzing device （BiteEye, GC, Tokyo, Japan）. Maximum bite force was also measured by using an occlusal force meter （Morita, Osaka, Japan）. Wilcoxon’s rank sum test was used for comparing the masticatory performance, occlusal contact area and maximum bite force between the two groups. Spearman’s rank correlation coefficient was used to evaluate the relationship between masticatory performance and craniofacial morphology.
Results: Masticatory performance, occlusal contact area and maximum bite force were significantly lower in the patient group than in the control group. These results suggest that remarkable skeletal discrepancy and lack of tooth contact in the anterior regions and lateral segments may yield a decrease in occlusal contact area, maximum bite force and masticatory performance. A negative correlation was found between masticatory performance and gonial angle and ANS-Me, whereas a positive correlation was found between masticatory performance and chewing time. These findings suggest that the load on the masticatory muscles was reduced in patients with mandibular prognathism due to a decrease in masticatory performance, resulting in the opening of the gonial angle which is the attachment area of the masseter muscle, and in the enlargement of anterior lower facial height.
Conclusions: A close relationship between masticatory performance and craniofacial morphology was found in the patient group with mandibular prognathism. The fully automatic measuring system is considered to be useful for evaluating masticatory performance in patients objectively and quantitatively in a short time.

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Beckwith-Wiedemann syndrome （BWS） is characterized by exomphalos, macroglossia, and gigantism. Macroglossia is observed in 97.5％ of BWS cases. Here we report the case of a patient with BWS who needed respiratory management following tongue reduction. An 18-year-old man with macroglossia was referred to our department due to concerns of relapse after orthodontic treatment. He had a history of tongue reduction in infancy, and recurrent macroglossia was observed with growth. The patient underwent a tongue reduction following diagnosis of macroglossia. However, immediately after surgery, obstruction of the upper airway due to swelling of the tongue was noted and it was decided to re-intubate the patient. As swelling improved on the second day of surgery, extubation was performed and a nasal airway was inserted. The nasal airway was extubated on the third day of surgery. No particular respiratory problems were observed. Oral ingestion was initiated on the fourth day. In cases of tongue reduction, perioperative management is important considering the possibility of re-intubation for upper airway obstruction.

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In patients with severe mandibular prognathism, maxillary deficiency is commonly seen. We report the successful surgical orthodontic treatment of a patient with severe mandibular prognathism and narrow maxilla. A male aged 26 years and 8 months with a chief complaint of anterior crossbite was diagnosed with severe skeletal ClassⅢ and Angle ClassⅢ malocclusion with a narrow maxilla. We aligned the lower dental arch, followed by surgically assisted rapid palatal expansion （SARPE） for the maxilla using two distractors placed on premolars and molars to expand the posterior area more widely than the anterior area of the maxillary dental arch; as a result, the arch form of the maxilla was well corrected and coordinated with the mandible. Following maxillary advancement and impaction by Le FortⅠ osteotomy and mandibular set-back, sagittal split ramus osteotomy （SSRO） improved the patient’s occlusion and facial profile. The resultant occlusion and satisfactory facial profile were maintained during the 2-year retention period.

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