[Correlation of bone resorption induced by orthodontic tooth movement and expression of RANKL in rats]

ABSTRACT

The product of RANKL gene expression has a fundamental role in bone resorption and activates the chain of osteoclast differentiation from its predecessor cells. Reports of this gene participation and role in physiologic and pathologic bone resorption led to hypothesis that it may play a role in bone resorption induced by orthodontic tooth movement. A closed coil spring [Dentaurum Ispringen, Germany] was fixed by two pieces of ligature wires to mesial side of the maxillary right first molar and anteriorly to both incisors of fifteen 7 week old Wistar male rats to tip the first molars mesially. The maxillary left first molar of each animal used as an internal control group for the contralateral tooth. The animals were sacrificed on the 21St day of the experiment and the tissue from the mesial side of maxillary molars was used for PCR test. Wilcoxon Sign Rank test was used for densitometric analysis of RANKL mRNA on the electrophoresis gel. Statistical analysis showed a significant increase in expression of gene in the experimental group compared to the control one [P<0.002]. Genuineness of the PCR tests was verified by household gene of GAPDH. Based on the data obtained in controlled environment of the study, RANKL expression increased significantly following bone resorption induced by orthodontic tooth movement