title: Assessment of bone density in the posterior maxilla based on Hounsfield units to enhance the initial stability of implants.
abstract: OBJECTIVE
  The poor bone quality that exists in the posterior maxilla is associated with lower initial stability and higher failure rates in implants. This study examined the bone densities of edentulous posterior maxillae by computed tomography (CT).
  
  
  METHODS
  Based on CT images, the voxel values representing implant replacement in the posterior maxillary regions of 30 patients were calculated in the range from 150 to 2,000 Hounsfield units (HU). The bone densities of these regions were categorized according to Misch's classification and compared among individuals and between sexes.
  
  
  RESULTS
  The average of the median individual CT values was 495 HU (95% confidence interval: 442-547 HU) and was significantly higher in males than in females. Most of the bone in the posterior maxillae was classified as D3 (350-850 HU) or D4 (150-350 HU) according to Misch's classification, comprising 50% and 32% of the entire regions, respectively.
  
  
  CONCLUSIONS
  More than 80% of the edentulous posterior maxillae consisted of porous cortical crest or no cortical bone according to CT, although the bone densities varied markedly among individuals. More detailed assessments of bone density may be useful to enhance initial stability of implants in the posterior maxilla.
authors.affiliation: Department of Prosthodontics and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan.
authors.forename: Motofumi
authors.initials: M
authors.lastname: Sogo
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ikebe
authors.forename: Tsung-Chieh
authors.initials: TC
authors.lastname: Yang
authors.forename: Masahiro
authors.initials: M
authors.lastname: Wada
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Maeda
mesh_terms: D000328:Adult; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D003724:Dental Arch / Q000000981:diagnostic imaging; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging*; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D012737:Sex Factors
chemical_list: D015921:Dental Implants