[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.

[The accuracy of 3D-CT volume rendering for craniofacial linear measurements].

PURPOSE: This study was designed to determine the consistency of craniofacial measurements using spiral computed tomography volume rendering by computer systems and sliding caliper. METHODS: The study population consisted of 12 cadaver heads which were examined with spiral CT. The archived CT data were transferred to a workstation, and 3D-CT volume rendered images were generated using computer graphics tools. Linear measurements (n = 20), based upon conventional craniometric anatomical landmarks (n = 16) were made, by Display Tools and sliding caliper respectively. The consistency between the two measurements was analyzed by paired t test using SAS9.0 software package. RESULTS: The results demonstrated no statistically significant difference between imaging measurement and physical measurement, P > 0.05. CONCLUSIONS: There is significant consistency between spiral CT measurement and physical measurement for craniofacial linear distance. 3D-CT volume rendering images using craniometric measurements can be used for clinical and basic studies in stomatology.