title: Detecting bone loss along dental implants by subtraction of panoramic radiographs.
abstract: OBJECTIVE
  To test an extended subtraction method for measuring changes in bone along dental implants depicted on non-standardized panoramic radiographs.
  
  
  METHODS
  The measuring method consisted of a subtraction module extended with modules correcting gray values, correcting geometry and defining the region of interest mesial and distal of dental implants. It was applied to an archive of panoramic radiographs of implant patients who had been monitored up to 16 years.
  
  
  RESULTS
  Significant loss of gray value was demonstrated at a constant rate of 0.6 units per month throughout the study. This indicates gradual bone loss on the mesial and/or distal sides of the implants. Females were found to lose bone at a higher rate than males. Smokers and non-smokers, and various implant strategies yielded the same rate of bone loss.
  
  
  CONCLUSIONS
  The measuring method is a helpful tool to monitor changes around implants even when non-standardized radiographs are being used. Whereas changes of marginal bone level are increased five to eight times during the first year after surgery, the present method shows gradual loss of bone during 15 years after surgery.
authors.affiliation: Department of Oral and Maxillofacial Radiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University, Amsterdam, The Netherlands. w.geraets@acta.nl
authors.forename: Wil G M
authors.initials: WG
authors.lastname: Geraets
authors.forename: Hans G C
authors.initials: HG
authors.lastname: Verheij
authors.forename: Daniel
authors.initials: D
authors.lastname: Wismeijer
authors.forename: Paul F
authors.initials: PF
authors.lastname: van der Stelt
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging* / Q000209:etiology; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D005260:Female; D006801:Humans; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging* / Q000534:rehabilitation*; D008297:Male; D011862:Radiography, Panoramic; D013382:Subtraction Technique; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants