Department of Orthodontics, Erciyes University, Kayseri, Turkey.
Eur J Orthod. 2010 Oct;32(5):496-504. doi: 10.1093/ejo/cjp124. Epub 2010 Jan 25.
The aim of this study was to histologically evaluate and compare the effects of the systemic administration of L-thyroxine (TX) and doxycycline (DX) on orthodontically induced root resorption, Twenty-eight male 50- to 60-day-old Wistar rats were used. Seven rats served as the baseline control. Seven animals received TX (20 μg/kg bodyweight/day) and seven DX (1.2 mg/kg bodyweight/day), by means of a mini-osmotic pump implanted subcutaneously. Seven rats were separated as a sham, in order to evaluate the pure effect of the surgical procedure on the animals' health. Tooth movement (TM) was achieved with a continuous force of 50 g by placing Elgiloy coil springs between the right maxillary first molar and incisors for 14 days. The animals were sacrificed and specimens containing the appliance and maxillary tooth-bearing segments were processed for light microscopy. The surface area of root resorption lacunae was measured histomorphometrically using digital photomicrographs. To evaluate the resorptive changes on the molar root surface of each group, scanning electron microscopy (SEM) examinations were also carried out. Statistical evaluation of root resorption percentages was performed using Kruskal-Wallis analysis of variance test. Multiple comparisons were determined by the Student-Newman-Keuls method. The level of significance was set at P < 0.05. Histomorphometric analysis of root resorption, expressed as a percentage, showed that the average relative root resorption affecting the maxillary molars on the TM side was 0.32 ± 0.25 in the TX and 0.26 ± 0.06 in the DX groups and 2.19 ± 0.86 in the control. Statistically significant inhibition of root resorption was determined both in the TX and DX groups (P < 0.001) on the TM side. There was no statistically significant difference in relative root resorption between the TX and DX groups. Systemic administration of TX and DX demonstrated similar effects on root resorption in rats and may have inhibitory effects on orthodontically induced resorptive activity.
本研究旨在通过组织学评估和比较左旋甲状腺素（TX）和强力霉素（DX）全身给药对正畸诱导的牙根吸收的作用。将 28 只 50-60 天大的雄性 Wistar 大鼠用于该研究。其中 7 只作为基线对照。7 只动物通过皮下植入的微型渗透泵给予 TX（20μg/kg 体重/天）和 DX（1.2mg/kg 体重/天）。7 只动物作为假手术组，以评估手术过程对动物健康的纯效应。通过在右侧上颌第一磨牙和切牙之间放置 Elgiloy 螺旋弹簧施加 50g 的持续力，实现牙齿移动（TM），持续 14 天。处死动物后，将包含矫治器和上颌带牙段的标本进行光镜处理。使用数字摄影显微镜对牙根吸收陷窝的表面积进行组织形态计量测量。为了评估每组磨牙根表面的吸收变化，还进行了扫描电子显微镜（SEM）检查。使用 Kruskal-Wallis 方差分析检验对牙根吸收百分比进行统计学评估。通过 Student-Newman-Keuls 法进行多重比较。显著性水平设为 P < 0.05。以百分比表示的牙根吸收的组织形态计量分析显示，在 TM 侧，TX 组和 DX 组中影响上颌磨牙的平均相对牙根吸收分别为 0.32 ± 0.25 和 0.26 ± 0.06，而对照组为 2.19 ± 0.86。在 TM 侧，TX 组和 DX 组均观察到牙根吸收的显著抑制（P < 0.001）。TX 组和 DX 组之间的相对牙根吸收没有统计学差异。TX 和 DX 的全身给药对大鼠的牙根吸收表现出相似的作用，可能对正畸诱导的吸收活性具有抑制作用。
