Purpose
The objectives of this study were to investigate the effect of exogenous injected local receptor activator of nuclear factor-kappa ligand (RANKL) inducing osteoclastogenesis during the tooth germ eruption and alveolar bone development in mi...
Purpose
The objectives of this study were to investigate the effect of exogenous injected local receptor activator of nuclear factor-kappa ligand (RANKL) inducing osteoclastogenesis during the tooth germ eruption and alveolar bone development in mice.
Materials and Methods
On postnatal 3(PN3), 40 fetal mice were randomly divided into the control and experiment groups. In experiment groups, subcutaneous injection of RANKL (0.4 mg/kg) into inferior mandible areas of mice daily until PN11. On day 7, 9, 11 and 13 of 10 mice (control 5 animals and experiment 5 animals) were sacrificed, respectively. Micro-CT reconstructed images of the lower incisors and molars were used to survey the level of tooth eruption. Longitudinal sections of the mandibles were prepared for H & E and TRAP staining to perform the TRAP-positive cell counting. Statistical comparisons were carried out using Student’s t-tests (P < 0.01).
Results
The incisal tooth eruption of mice on day 11 and 13 in RANKL group appeared significantly greater than in PBS (phosphate buffered saline) group. The first molar tooth eruption in the RANKL group was slightly faster than in PBS group on day 9 and 11(P < 0.01). RANKL group showed the significantly large number of multinuclear TRAP-positive osteoclasts on day 7, 9 and 11 (P < 0.01).
Conclusions
The facilitation of tooth eruption probably is mediated by exogenous RANKL. However, this effect expressed transiently of tooth eruption process. Short-term local administration of RANKL may be a method by which to facilitate the tooth eruption in mice with a delayed tooth eruption.