title: Crevicular alkaline phosphatase activity during the application of two patterns of orthodontic forces.
abstract: OBJECTIVE
  The objective of this study was to test the hypothesis that using a gradually increasing orthodontic force would induce an increased activity of osteoblasts compared to a relatively constant orthodontic force.
  
  
  METHODS
  Twelve orthodontic patients participated in this study. In a split mouth design, one maxillary canine undergoing distal movement received a relatively constant continuous retraction force, while the contralateral canine received a gradually increasing retraction force. Gingival crevicular fluid (GCF) samples were collected from both experimental sites at weekly intervals and analysed spectrophotometrically for the activity of alkaline phosphatase enzyme, which was used as a biological marker for osteoblastic activity.
  
  
  RESULTS
  With the exception of the maxillary first molar receiving gradually increasing orthodontic force, the results revealed a consistent pattern of alkaline phosphatase activity. This pattern included an initial rise from baseline to the first week, then a peak in the second week. This peak was followed by a reduction in enzyme activity in the third week. The overall increases in enzyme activity at the maxillary canines and the maxillary first molars in the relatively constant force group were 179·76% and 332·90%, respectively. The overall increases in enzyme activity at the maxillary canines and the maxillary first molars in the gradually increasing force group were 304·81% and 493·08%, respectively.
  
  
  CONCLUSIONS
  The use of gradually increasing orthodontic force induces increased activity of osteoblasts during the initial stage of orthodontic tooth movement compared to that induced by a relatively constant orthodontic force.
authors: Hani
authors: H
authors: AlSwafeeri
authors: Walid
authors: W
authors: ElKenany
authors: Mohamed
authors: M
authors: Mowafy
authors: Myriam
authors: M
authors: Helmy
mesh_terms: D000293:Adolescent; D000469:Alkaline Phosphatase / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis; D001696:Biomechanical Phenomena; D003481:Cuspid / Q000502:physiology; D003722:Dental Alloys / Q000737:chemistry; D005260:Female; D005883:Gingival Crevicular Fluid / Q000201:enzymology*; D006801:Humans; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy; D008963:Molar / Q000502:physiology; D009532:Nickel / Q000737:chemistry; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D010006:Osteoblasts / Q000502:physiology; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium; D000469:Alkaline Phosphatase
keywords: Alkaline phosphatase,; gradually increasing force; osteoblasts,