THE MEASUREMENT OF ACID AND ALKALINE-PHOSPHATASE IN GINGIVAL CREVICULAR FLUID DURING ORTHODONTIC TOOTH MOVEMENT

This study examines acid and alkaline phosphatase activities in gingiv al crevicular fluid (GCF) to learn whether bone turnover dynamics can be monitored in human subjects during orthodontic tooth movement. Thre e female subjects were observed longitudinally to assess tooth movemen t, plaque, and inflammation. For each subject, one randomly selected p remolar served as the control and was not treated, and another was mov ed buccally with 100 gm of force. The GCF was collected weekly and ass ayed for phosphatases. Alkaline phosphatase peaked between the first a nd third weeks, followed by an increase in acid phosphatase between th e third and sixth weeks. After the first week, tooth movement averaged 0.9 mm. An additional 0.9 mm of movement occurred during the next 3 w eeks, followed by 1.4 mm during weeks 4 to 6. Thirty additional patien ts, randomly divided into headgear/biteplate, bionator, and control gr oups, were also sampled cross-sectionally at the maxillary first molar s. The GCF phosphatase activities were assessed as functions of locati on on the tooth, treatment modality, duration of treatment, gingival i nflammation, and plaque accumulation. The plaque index did not show a relationship to either acid or alkaline phosphatase activity on the me sial or distal in the treated groups. However, alkaline phosphatase in creased with inflammation on the distal in treated groups and acid pho sphatase was consistently higher on the mesial than on the distal in t he treatment groups. Alternating peaks of acid and alkaline phosphatas e were found in GCF of treated teeth as functions of treatment duratio n. The sequence of these changes is similar to that reported for alveo lar bone turnover in a rodent orthodontic tooth movement model. We con clude that phosphatase activities in GCF may be a useful means for mon itoring tissue responses to orthodontic treatment.