THE EFFECTS OF EXOGENOUS PROSTAGLANDINS ON ORTHODONTIC TOOTH MOVEMENTIN RATS

The long-term effects of varying concentrations and frequencies of inj ectable, exogenous prostaglandin E(2) (PGE(2)) on the rate of tooth mo vement and the amount of root resorption were evaluated. There were 13 2 male Sprague-Dawley rats 8 weeks old that initially weighed 225 to 2 50 gm. Five animals were in a pilot study, while seven were baseline c ontrols and eight were appliance controls. The remaining 112 animals w ere divided into two experimental time periods of 2 and 4 weeks. Then, each experimental time period was divided into four subgroups of 14 a nimals based on concentration levels of PGE(2) injections, i.e., 0.1, 1.0, 5.0 and 10.0 mu g. Half of these animals in the dosage subgroup r eceived a single injection at appliance placement and the other half r eceived weekly injections. A fixed orthodontic appliance consisting of closed-coil nickel-titanium springs were ligated between the maxillar y incisors and maxillary first molars. The initial activating force wa s 60 gm. The results showed that injections of exogenous PGE(2) over a n extended period of time in rats did enhance the amount of orthodonti c tooth movement. However, there was no statistically significant diff erence in tooth movement between the single and multiple injection gro ups or among the four concentration levels of PGE(2) used in either th e 2- or 4-week time periods. The amount of root resorption as seen fro m scanning electron micrographs did increase with the use of prostagla ndin injections, specifically with increased numbers of injections and with increased concentrations of PGE(2).