Objective: To investigate orthodontic tooth movement of local injections of recombinant human soluble receptors in rats, to understand the scope of minimum valid concentration and the effects to the receptor activator of nuclear factor-кB ligand (RANKL).
Methods: The first molars of fifty-two male Sprague-Dawley rats were moved mesially by using a coil spring. Forty-eight rats were divided into three groups and each group had four subgroups, four rats served as the control. From the 1st day , they received different concentration of sIL-1-RII, sTNF-RI and their combinations. On the 14th day, the amount of tooth movement was measured. Selected tissue sections were stained by haematoxylin-eosin(HE), tartrate-resistant acid phosphatase(TRAP) and strept sctividin-biotin complex(SABC) .
Results: Compared to the control group, tooth movement of the 4 ug/ml,0.8 ug/ml,0.16 ug/ml subgroups of each group was reduced by approximately 50% (P<0.01); the number of TRAP-positive cells and the expression of RANKL on the tension side of tooth was both reduced significantly as well( P<0.01). Whereas the data from the 0.032 ug/ml subgroups was meaningless from a statistical view of point ( P>0.05); and there were no significant difference among three receptor groups ( P>0.05).
Conclusion: Local injections of sIL-1-RII and sTNF-RI on orthodontic tooth could reduce the incidence of root resorption, the range of minimum valid concentration may be between 0.032ug/ml~0.16 ug/ml, and possibly osteoclast and odontoclast can be regulated by influencing the expression of RANKL.