Inhibitory effect of baicalin on orthodontically induced inflammatory root resorption in rats.

OBJECTIVE: This study investigated the inhibitory effect of baicalin on orthodontically induced inflammatory root resorption in rats. METHODS: Forty-five male Wistar rats were randomly divided into three groups of 15 rats each. Fifty grams of force was used to establish an orthodontic tooth movement model. Baicalin (40 mg/kg) was locally injected into rats in the baicalin group at 3-day intervals; concurrently, normal saline was injected into rats in the negative control group. On the 21st day after orthodontic treatment, the tooth movement distance and root resorption area ratio were measured. Histomorphology changes were observed by hematoxylin and eosin staining and immunohistochemistry. RESULTS: There was no significant difference in tooth movement distance between groups. The root resorption area ratio was significantly lower in the baicalin group than in the negative control group. Runx-2 expression was significantly higher in the baicalin group than in the negative control group, while tumor necrosis factor (TNF)-α expression was significantly lower in the baicalin group than in the negative control group. CONCLUSIONS: Baicalin inhibits orthodontically induced inflammatory root resorption by enhancing the expression of Runx-2 and reducing the expression of TNF-α, but does not affect tooth movement distance.

[Changes of aspartate aminotransferase and alkaline phosphatase activities in gingival crevicular fluid during rapid palatal expansion].

PURPOSE: This study was designed to examine the changes of aspartate aminotransferase (AST) and alkaline phosphatase(ALP) activities in gingival crevicular fluid (GCF) during rapid palatal expansion, and to explore the relationship between these changes and periodontal tissue remodeling. METHODS: Thirty-eight patients (aged 10.5 to 12.8years) who required opening of the palatal suture as the first stage of their orthodontic treatment were included and studied. The patients were divided into two groups: control group (18 cases) and experimental group (20 cases). GCF samples were collected at 6 observation periods with filter paper strips: before activation, 24 hours and 7 days after activation, 7 days, 14 days, and 28 days in retention. AST and ALP activities were determined by a full automatic biochemical analyzer, and the results were expressed as total AST and ALP activities. The data was analyzed with SAS (r) Proprietary Software Version 9.00 for paired t test and two-sample t test. RESULTS: AST activity was significantly elevated after 24-hour activation in the test group (P<0.05), but after 7-day activation in the control group (P<0.01). Both in the control and experimental group, AST activity remained high until 28-day in retention (P<0.01). AST activity in the test group was significantly greater compared to the control group from 24-hour activation to 28-day in retention (P<0.05). ALP activity increased significantly from 7-day activation to 28-day retention in the control and experimental group (P<0.01), and there was statistically significant difference between the control and the experimental group from 7-day to 28-day in retention (P<0.01). CONCLUSION: Our results suggest that AST and ALP levels in GCF may reflect the tissue remodeling which occurs in the periodontium during rapid palatal expansion to some degree.

[Effects of first premolar extractions on third molar angulations].

OBJECTIVE: To compare the inclinations of third molars of patients treated orthodontically with and without premolar extractions. METHODS: Records of 37 first premolar extraction patients and 32 nonextraction patients were examined. The pretreatment and posttreatment panoramic radiographs were analyzed. The angles were measured between the long axis of the third molar and the occlusal plane and between the long axis of the third molar and the long axis of the second molar. Changes in third molar angulations from pretreatment to posttreatment for two groups were compared by Mann-Whitney U-test. RESULTS: There were statistically significant difference between the extraction and nonextraction groups in the median angle formed by the long axis of third molar angulation relative to the occlusal plane (P<0.05) and the second molar (P<0.05) in mandible but not in maxillary. In the extraction group, at the end of the orthodontic treatment, the mandibular third molars showed more uprighting than did the maxillary third molars. CONCLUSION: Orthodontic treatment involving premolar extractions improves mandibular third molar angulations.

[Study of the incisive alveolar structure in different vertical facial types between osteal Class III malocclusion and normal occlusion].

PURPOSE: To investigate the relationship of the incisive alveolar structure and vertical facial type between osteal Class III malocclusion and normal occlusion. METHODS: Forty-seven lateral cephalometrics of patients with osteal Class III malocclusion and forty-three lateral cephalometrics of controls with normal occlusion were randomly selected before treatment. Then the incisive alveolar structure was measured and analyzed, the results were analyzed with Student's t test. RESULTS: (1) In osteal Class III malocclusion; the UP value in the group of high mandibular angle decreased significantly than that in the groups of middle and low mandibular angle (P<0.05); the LA and MxAD value in the group of high mandibular angle decreased significantly than that in the group of middle mandibular angle (P<0.05). (2) In normal occlusion, the MdAD and LA value in the group of high mandibular angle decreased significantly than that in the groups of middle and low mandibular angle(P<0.05). (3) In patients with the same mandibular angle,the LA and MdAD value in normal occlusion increased significantly than those in osteal Class III malocclusion (P<0.05);the UP value, in normal occlusion increased significantly than osteal Class III malocclusion within the groups of middle and low mandibular angle (P<0.01). CONCLUSIONS: The incisive alveolar structure was different in different vertical facial type and the same vertical facial types between osteal Class III malocclusion and normal occlusion.