title: Physical properties of root cementum: part 6. A comparative quantitative analysis of the mineral composition of human premolar cementum after the application of orthodontic forces.
abstract: BACKGROUND
  The aim of this study was to examine quantitatively with electron probe microanalysis (EPMA) the calcium (Ca), phosphorus (P), and fluoride (F) concentrations in human first premolar cementum after the application of light and heavy orthodontic forces.
  
  
  METHODS
  Thirty-six maxillary and mandibular first premolars (18 experimental, 18 control) were extracted from 16 subjects (10 male, 6 female; mean age, 13.9 years; range, 11.7-16.1 years) who were randomly assigned to the light-force or the heavy-force group. In the light-force group, 25 g of buccally directed force was applied to the experimental premolar; in the heavy-force group, 225 g of buccally directed force was applied to the experimental premolar. The contralateral premolar served as the control. The experimental and control premolars were extracted 28 or 29 days after initial force application and prepared for EPMA. The Ca, P, and F concentrations were measured on the buccal and lingual surfaces at the midpoint of the cervical, middle, and apical thirds of the root from the outer to the middle to the inner third of the cementum.
  
  
  RESULTS
  Little change was found in the mineral composition of cementum after the application of light forces; however, there was a trend toward an increase in the mineral composition (Ca, P, and F) of cementum at various areas of periodontal ligament compression. The application of heavy forces caused a significant (P = .000) decrease in the Ca concentration of cementum at certain areas of periodontal ligament tension. The application of both light and heavy orthodontic forces did not appear to influence the F concentrations in cementum.
  
  
  CONCLUSIONS
  Heavy orthodontic forces cause alterations in the mineral content of cementum; light forces cause little change.
authors.affiliation: Faculty of Dentistry, Sydney Dental Hospital, University of Sydney, Sydney, Australia.
authors.forename: Teriko
authors.initials: T
authors.lastname: Rex
authors.forename: Om Prakash
authors.initials: OP
authors.lastname: Kharbanda
authors.forename: Peter
authors.initials: P
authors.lastname: Petocz
authors.forename: M Ali
authors.initials: MA
authors.lastname: Darendeliler
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001641:Bicuspid / Q000737:chemistry*; D002118:Calcium / Q000032:analysis; D002648:Child; D003739:Dental Cementum / Q000737:chemistry*; D003799:Dental Stress Analysis; D004577:Electron Probe Microanalysis; D005260:Female; D005459:Fluorides / Q000032:analysis; D006801:Humans; D008297:Male; D010513:Periodontal Ligament / Q000502:physiology; D010758:Phosphorus / Q000032:analysis; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D017001:Tooth Demineralization / Q000209:etiology*; D014087:Tooth Movement Techniques / Q000009:adverse effects*
chemical_list: D010758:Phosphorus; D005459:Fluorides; D002118:Calcium