The Effect of local injection of strontium on inhibition and repair of orthodontically induced root resorption in rats (An experimental study)

Abstract

Background: Strontium (Sr) is an alkaline earth trace metal cation that has a high
affinity for hydroxyapatite. This study aimed to examine the histological effect of
locally injected strontium (Sr) on prevention and repair of induced root resorption
of rat molar subjected to orthodontic tooth movement.
Materials and Methods: Eighteen ten-week- old male Wister rats were randomly
divided into two groups of nine animals for two experiments. In both experiments;
uniform standardized expansive springs were used to move maxillary first molars
buccally for three weeks and then removed. In experiment No.1, at the time of
spring placement, 0.25 ml of the strontium chloride solution at a concentration 240
mg/ml was injected at the sub-periosteum of the buccal side of the maxillary left
first molar which was the experimental side. On other hand, 0.25 ml of distilled
water was injected at the sub-periosteum of the buccal side of the right maxillary
first molar which was the control side. The injections repeated every other day for
three weeks whereas in experiment 2 it was begun at the day of spring removal and
repeated every other day for another three weeks. After that the animals were
scarified humanly and biopsies were taken for histological examination.
Results: In experiment 1 the side injected with strontium showed statistically
significant lesser root resorption than control side, while in experiment two the
strontium injected side showed significantly more repair.
Conclusion: Results of the study suggested that local injection of strontium can
inhibit root resorption process and enhance repair.