Relationship between the developmental variation in tongue function with open-bite and the articulatory disorder

本研究旨在通过了解前牙开咬舌位异常儿童的舌位和发音特点，发展其口腔功能。每名受试者被要求说出短句“Hana ga Saita”，并使用语音声学分析对开牙合和正常牙合儿童的所有录音进行比较。整个声音波形由声谱图和共振峰历史来表示。提取了无齿牙槽擦音/s/的共振峰频率（F1、F2、F4）。由于F4被认为反映了说话者声道的长度，因此将F1和F2除以F4，以便对它们进行相对评估。开牙合患者的F1和F2频率明显高于正常牙合患者。结果表明，开牙合患者的牙槽嵴变为牙间，擦音变为近音。首先，观察了口咽期舌背中央沟的正常发育过程。将20名女性按牙期分为4组，采用B+M模式观察饮水时舌在左右上颌第一磨牙连线上的运动。结果表明，中央沟形成成熟的时期为替牙期早期。此外，还对舌背B型矢状面图像进行了分析，以了解不同牙合组舌体在静止位时的舌位特征。探讨了舌背曲度与覆牙合的关系。结果表明，舌在静止位时的姿势影响前切牙的关系，开牙合儿童舌背相对平坦。

This study intended to develop the oral function of children who had the problem in tongue posture with anterior open bite by clarifying both their tongue positions and the articulation characteristics. Each examinee was asked to say the short sentence "Hana ga Saita", and all the recorded sound was compared between open bite and normal bite children using the acoustic analysis of speech. The whole sound-waveform was expressed by both the sound-spectrogram and the formant history. The formant frequencies (F1, F2, F4) of voiceless alveolar fricative sound /s/ were extracted. As F4 is supposed to reflect the length of a talker's vocal tract, both F1 and F2 were divided by F4 in order to evaluate them relatively. The frequencies of F1 and F2 in patients with open bite were significantly higher than those in patients with normal bite. It is suggested that in patients with open bite the alveolar became an interdental, the fricative became an approximant.Tongue postures were analyzed by the ultra-sonography. First, normal developmental process in the central groove formation on tongue dorsum was observed at oral swallowing stage. 20 females were divided into four groups according to their dental stages, their tongue movement at the line connecting the left and right upper first molars while drinking water was observed by B+M Mode. The results suggested that the time at when the central groove formation became mature was the early mixed dentition period. Furthermore, to find the characteristics of the tongue posture in rest position among different occlusal groups, B Mode sagittal images of the tongue dorsum were analyzed. The correlation between the curvature of tongue dorsum (CTD) and the over-bite was discussed. The results showed that the tongue posture in rest position influenced the anterior incisor relationship and the tongue dorsum of open bite children was relatively flat.