Objective This study was conducted to measure the mandibular incisive canal (MIC) by cone beam computed tomography(CBCT)and to assess 3?dimensional structure, course and adjacent structure of the MIC , in order to ensure safe region for surgery of the mandibular interforaminal area. Methods A total of the CBCT images from 83 patients were studied and measured. The detection rates of MIC were calculated The diameter of the MIC and the distances from MIC to the labial and lingual cortices and the inferior border of the mandible and tooth tips were measured at canines and lateral incisors. Results MIC was found in 67.8%of the patients. In the position of canine, the diameter of MIC, the mean distance of the MIC to the tips of the teeth, to the buccal border of the mandible , to the lingual border of the mandible and the inferior border of the mandible were (1.3±0.4), (8.9±2.9), (4.3±0.9), (5.2±1.1) and (8.6± 1.5) mm, respectively. In the position of the incisor, the distance of MIC, the mean distance of the MIC to the tips of the teeth, to the buccal border of the mandible , to the lingual border of the mandible and the inferior border of the mandible were (1.0 ± 0.3), (13.3 ± 4.0), (4.2 ± 0.9), (5.9 ± 0.9) and (8.9 ± 1.8) mm, respectively. Conclusion CBCT clearly show three dimensional structure, course and adjacent structure of the MIC. Preoperative CBCT can provide vital information for surgery of the mandibular interforaminal area.

Objective : To analyze the difference of urinary iodine level in Hashimoto thyroiditis ( HT) patients， and to explore the possible relationship between urinary iodine level and HT under different iodine nutritional sta- tus，so as to provide some references for reasonable iodine intake in HT patients． Methods : A total of 101 hospi- talized HT patients were selected as HT group and divided into 3 groups according to thyroid function : HT group with hyperthyroidism (41 cases) ．There were 25 cases in HT group with normal thyroid function．There were 35 cases in HT combined with hypothyroidism group．In addition，30 healthy subjects were selected as control group. Serum levels of thyroid stimulating hormone(TSH) ，triiodothyronine(T3 ) ，thyroxine (T4 ) ，thyroid peroxidase an- tibody (TPOAb) and thyroglobulin antibody (ATG) were detected by chemiluminescence assay．The size and mor- phological structure of thyroid organs were examined by ultrasonography．Urinary iodine was determined by catalytic spectrophotometry with arsenic and cerium．The nutritional status of iodine was classified into iodine deficiency ( < 100 μg/ L) ，iodine adequacy( 100 －199 μg/ L) ，iodine adequacy (200 －299 μg/ L) and iodine excess ( ≥ 300 μg/ L) ．Non-parametric test was used to compare urinary iodine level between HT group and control group，one- way ANOVA and t test were used to compare urinary iodine level between HT group and control group ，and Spearman correlation analysis was used to compare the correlation between urinary iodine level and T3 ，T4 ，TSH， ATG and TPOAb under different iodine nutrition status. Results : Compared with control group，ATG and TPOAb levels in HT group increased (P＜0. 001) ，and urinary iodine levels increased (P＜0. 05) ，with statistical signifi- cance．Compared with the control group in different thyroid function states，only the HT group with hypothyroidism increased the urinary iodine level (P＜0. 01) ，and the difference was statistically significant．Spearman correlation analysis showed that urine iodine level was positively correlated with ATG and TPOAb levels in iodine excess condi- tion (P＜0. 05) ，and urine iodine level was positively correlated with TSH level in iodine sufficient condition and iodine excess condition in HT patients (P＜0. 05) ． Conclusion The urinary iodine level of HT patients was high- er than that of normal people．When the urinary iodine level of residents is ≥ 300 μg/ L，iodine intake is prone to HT．When the urinary iodine level of HT patients is ≥ 200 μg/ L，iodine consumption is prone to hypothyroidism， and iodine intake should be limited.