THE EFFECTS OF EXOGENOUS PROSTAGLANDIN E(2) ON ROOT RESORPTION IN RATS

This study evaluated the amount and depth of root resorption associate d with varying concentrations and frequencies of injectable, exogenous prostaglandin E(2) (PGE(2)) in conjunction with orthodontic tooth mov ement in rats. The sample consisted of 155 maxillary right and left fi rst molars from 88, 8-week old, male Sprague-Dawley rats. The animals were divided into three control groups and two experimental groups. Th e control animals were divided into one nonappliance and two appliance groups. The experimental animals were divided into 2- and 4-week expe rimental time periods that were further subdivided based on single and weekly injection intervals of PGE(2) and four different injectable co ncentration levels, i.e., 0.1, 1.0, 5.0, and 10.0 mu g. A fixed orthod ontic appliance was ligated between the maxillary incisors and maxilla ry first molars with closed-coil nickel-titanium springs. The applianc e had an initial activating force of 60 gm. Serial histologic sections of the mesial root of the maxillary first molar were made, and a quan titative histomorphometric analysis of root resorption on the mesial a nd distal surfaces was performed. This study demonstrated increased ro ot surface resorption when using exogenous PGE(2) injections to enhanc e orthodontic tooth movement over a 2-week period with increasing root resorption on the mesial surface as compared with the distal surface in PGE(2) treated teeth. No differences in root resorption were found with either multiple injections or increasing concentration in the 4-w eek experimental group. Local injection of PGE(2) appeared to have no effect on the number or depth of resorption lacunae in either the 2- o r 4-week groups.