title: Effect of Osteoporosis on Bone Density of Orthognathic Osteotomy Sites in Maxillofacial Region.
abstract: OBJECTIVE
  The aims of this study were to investigate the availability of Hounsfield unit (HU) measurement of computed tomography (CT) in evaluating the bone density of certain sites by comparing bone density between CT and dual-energy x-ray absorptiometry (DEXA), and to evaluate the effects of osteoporosis on osteotomy sites in orthognathic surgery.
  
  
  METHODS
  This retrospective study included 80 patients who had undergone both facial CT and DEXA at our hospital. We selected 7 regions of interest from among the osteotomy sites in bimaxillary orthognathic surgery. The patients were assigned to either the normal (control) group (n = 40) or the abnormal group (n = 40), and HU values were measured in each region of interest.
  
  
  RESULTS
  There were statistically significant differences in the mean HU values between 2 groups at all the osteotomy sites in the maxilla and mandible, with the normal group showing higher values than the abnormal group (P < 0.05). In addition, there was a significant positive correlation between T-scores obtained with DEXA and the HU values on CT at the osteotomy sites (P < 0.01). Multiple regression analysis indicated that the abnormal group was more negatively associated with 6 osteotomy sites except for 1 maxillary area, as compared with the normal group.
  
  
  CONCLUSIONS
  Measurement of HU values on CT can be valuable in assessing bone density of the maxilla and mandible. It is suggested that osteoporosis may affect bone density at the osteotomy sites in orthognathic surgery, and the preoperative measurement of HU values might be useful in predicting unfavorable fracture or the risks involved in such surgery.
authors.affiliation: *Division of Oral and Maxillofacial Surgery, Department of Dentistry †Department of Otorhinolaryngology ‡Office of Biostatistics §Department of Radiology, Ajou University School of Medicine, Suwon, Republic of Korea.
authors.forename: Sung Woon
authors.initials: SW
authors.lastname: On
authors.forename: Hyun Jun
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jayoun
authors.initials: J
authors.lastname: Kim
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Choi
authors.forename: Young Wook
authors.initials: YW
authors.lastname: Jung
authors.forename: Seung Il
authors.initials: SI
authors.lastname: Song
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D063169:Dentofacial Deformities / Q000150:complications / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging* / Q000601:surgery; D008437:Maxilla / Q000000981:diagnostic imaging* / Q000601:surgery; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D056948:Orthognathic Surgical Procedures / Q000379:methods*; D010024:Osteoporosis / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D010027:Osteotomy / Q000379:methods*; D012189:Retrospective Studies