Alkaline phosphatase activity in dental pulp of orthodontically treated teeth

Introduction: The aim of this study was to examine alkaline phosphatase (ALP) activity in the dental pulp of orthodontically treated teeth. Methods: Sixteen healthy subjects (mean age 17.0 ±1.6 years) who required extraction of 4 first premolars for orthodontic reasons participated. One maxillary first premolar subjected to orthodontic force was the test tooth. The contralateral first premolar, bracketed but not subjected to mechanical stress, was the control tooth. After a week of treatment, the first premolars were extracted and the dental pulp removed from the teeth. ALP activity was determined spectrophotometrically and the results expressed as units/liter per milligram of pulp tissue [U/(L x mg)]. Results: ALP activity was 89 ± 26 U/(L x mg) in the test teeth and 142 ± 33 U/(L x mg) in the control teeth. The difference between the groups was statistically significant (P < .01). Conclusions: Orthodontic treatment can lead to significant early-phase reduction in ALP activity in human dental pulp tissue.