Periodontal mechanosensitive thresholds of adult subjects with natural dentition and chronological change of the threshold with uncomfortable occlusion after orthodontic treatment

Purpose: The number of patients complaining of uncomfortable occlusion has recently increased. However, methods for differentiating dysesthesia from disorder of aesthesia causing uncomfortable occlusion have not been established. The purposes of this study were to set the normal range of periodontal mechanosensitive threshold in adult dentulous persons and to utilize clinically.<br> Methods: 32 adult dentulous subjects (20 males and 12 females, mean age: 26.1 ± 3.7 years) with normal dentition evaluated by add picture regulated bite force were selected. The subject teeth were 28 teeth between the bilateral second molar on maxillary and mandibular. Measurement was performed with their eyes closed, sitting on a chair. In measuring periodontal mechanosensitive threshold, von Frey's hair came into contact with the subject teeth from the labio-buccal surface side, and stimulation was applied in the lingual direction. Measurement was performed by a dentist with sufficient knowledge and training, and thresholds were determined applying the up-down method of the method of limits of psycho-physical measurement methods. The interquartile range of periodontal mechanosensitive threshold of the normal subjects was calculated.<br> Periodontal mechanosensitive threshold of the man complained uncomfortable occlusion after orthodontic treatment were measured from one month after the removal of the device every the 14^th.<br> Results: There were no abnormal occlusal contact both normal subjects and clinical case. It was shown that periodontal mechanosensitive threshold gradually increased from the anterior tooth to molar area. The interquartile range of periodontal mechanosensitive threshold was 0.5-1.7g in the maxillary anterior tooth area, 1.5-3.0g in the canine teeth, 1.5-4.0g in the premolar area, and 3.7-8.8g in the molar area. The interquartile range of periodontal mechanosensitive threshold was 0.3-1.0g in the mandibular anterior tooth area, 0.7-3.0g in the canine teeth, 0.8-5.0g in the premolar area, and 3.0-11.6g in the molar area.<br> Periodontal mechanosensitive threshold when one month passed was 190.0g or less in molar teeth and was 7.0g or less in anterior teeth. Afterwards, the value of periodontal mechanosensitive threshold was decreased. The value of periodontal mechanosensitive threshold when three months passed after removal device was decreased until the interquartile range, and uncomfortable occlusion was disappeared. The change was not shown in periodontal mechanosensitive threshold and uncomfortable occlusion when seven months passed after removal device.<br> Conclusion: These results revealed that periodontal mechanosensitive threshold become objective index of sensitive of teeth.