[Three dimensional reconstruction measurement study of palatal contour changes in different bone ages after rapid maxillary expansion].

Objective: To compare dental and skeletal changes after rapid maxillary expansion in patients with different bone ages. Methods: Thirty-seven patients in different growth period were divided into three groups according to cervical vertebral maturation (CVM). There were 13 patients in the growth acceleration group, 13 patients in growth peak group, and 11 patients in growth deceleration group. Cone-beam computed tomography (CBCT) images were segmented and reconstructed using Mimics image processing software to assess the change of palatal morphology before and after treatment. Statistical analysis was carried out using SPSS 17.0 software. Results: After the expansion the posterior teeth and alveolar bone were tilted and the mid-palatal suture was opened in all three groups. The first molar angle in the three groups decreased by 2.66°±1.04°, 3.53°±0.81° and 12.32°±1.64°, respectively and no significant difference was found between the acceleration group and the peak group (P >0.05), but the changes in the acceleration group and the peak groups were significantly less than that in the deceleration group (P<0.05). The palatal angle in the three groups increased by 6.01° ± 2.06°, 4.79° ± 1.31° and 6.73° ± 1.71°, respectively and no significant difference was found between the acceleration group and the deceleration group (P>0.05), but the changes in the acceleration group and the deceleration group were significantly greater than that in the peak group (P<0.05). The palatal cemento-enamel junction (CEJ) width, the middle palate width and the mid-palatal suture width in the three groups increased by (7.37 ± 1.31), (6.68 ± 0.72) and (5.13 ± 1.42) mm; (5.72±1.68), (4.82±1.66) and (3.42±1.15) mm; (3.14±0.45), (2.98±0.51) and (0.96±0.83) mm, respectively and no significant difference was found between the acceleration group and the peak group (P >0.05), but the changes in the acceleration group and the peak group were significantly greater than that in the deceleration group (P <0.05). Conclusions: The mid-palatal suture could be opened in patients in different CVM period. More skeletal and less dental effects were found in patients in the growth acceleration and peek group than in those in the growth deceleration group and the inclination of the alveolar bone could be avoided to a greater degree in patients in the growth peek group.

Quantitation of the pressing force required for feeling peripheral pulses.

A simple method has been developed for the quantitation of the pressing force, which is required to feel arterial pulse optimally by using finger tips on the radial artery. This force was measured by our transducer, which replaces the touch force generated by finger tips on the artery. This force, called the dead load, was traced 18 times in 8 hours on a volunteer, and the coefficient of variation of this load was 0.12. We selected 15 volunteers who had moderate touching force for plethysmography, and their dead loads were measured repeatedly 68 times over a week, where the mean and the standard deviation was 60 +/- 15 grams. The problems related to these research methodologies, which can bridge between traditional Chinese medicine and western medicine, were also discussed briefly.