title: Experimental evaluation of bone quality measuring speed of sound in cadaver mandibles.
abstract: OBJECTIVE
  To demonstrate in vitro the feasibility of speed of sound (SOS) measurements through the mandible and to investigate the relationships between mandibular SOS, local bone mineral density (BMD), and the ratio between trabecular and cortical thicknesses (Tb.Th/Cort.Th). The long-term goal is to find a safe, simple test for bone quality in sites for dental implant placement.
  
  
  METHODS
  Excised human mandibles (N = 23) were used for the measurement of sound transmission with two 1.6 MHz transducers. Three regions of interest (ROIs) were selected in each of the specimens, namely incisor, premolar, and molar regions. To determine short-term precision, 10 measurements (with repositioning between measures) were performed for each ROI. Local BMD and mandibular cross-sectional morphological characteristics were determined by dual x-ray absorptiometry (DXA) and computed tomography (CT).
  
  
  RESULTS
  The coefficient of variation for SOS was found to be 1%. SOS measurements at different sites were significantly different. A significant linear relationship was found between SOS and BMD (r2 = 0.62; P < .0001), whereas a nonlinear relationship was found between SOS and Tb.Th/Cort.Th (r2 = 0.53; P < .0001).
  
  
  CONCLUSIONS
  This in vitro study demonstrated the feasibility of SOS measurement through the mandible. Mandibular SOS reflects local BMD and Tb.Th/Cort.Th. In vivo studies are now required to confirm the predictive power of SOS measurement for bone quality assessment and its potential usefulness as a clinical diagnostic technique.
authors.affiliation: Laboratoire d'Imagerie Paramétrique, Université Pierre et Marie Curie Paris, Paris, France.
authors.forename: Iyad
authors.initials: I
authors.lastname: Al Haffar
authors.forename: Frédéric
authors.initials: F
authors.lastname: Padilla
authors.forename: Raphael
authors.initials: R
authors.lastname: Nefussi
authors.forename: Sami
authors.initials: S
authors.lastname: Kolta
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Foucart
authors.forename: Pascal
authors.initials: P
authors.lastname: Laugier
mesh_terms: D015502:Absorptiometry, Photon; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D015519:Bone Density; D002102:Cadaver; D003724:Dental Arch / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000648:ultrastructure; D003799:Dental Stress Analysis; D006801:Humans; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D012044:Regression Analysis; D015203:Reproducibility of Results; D013016:Sound; D018709:Statistics, Nonparametric; D014159:Transducers; D014463:Ultrasonography