O.T. DAVID, M. LERETTER, A. NEAGU#
“Victor Babeș” University of Medicine and Pharmacy, Timișoara, 2, Eftimie Murgu sq., 300041 Timișoara, Romania
Dental implant stability depends on the quality of bone in the target site. Although subjective bone quality assessments are still important, objective measurements of bone density by X-ray imaging is increasingly appreciated in implant planning. Using conventional computed tomography (CT), an objective bone density scale was established in terms of mean CT numbers of various bone types, which characterize their ability to attenuate X-ray beams. Cone-beam computed tomography (CBCT) is preferred for three-dimensional dental imaging because it is cheaper than CT and exposes the patient to lower doses of X-rays. The results of bone density measurements by CBCT, however, are less consistent than CT results: they depend on the type of CBCT device and on image acquisition parameters. Here we analyzed CBCT images of 46 patients, recorded in identical conditions by the same type of CBCT unit. We computed the CT numbers of cancellous bone from 400 potential implant sites. Moreover, for each site, we recorded the standard deviation of the CT numbers of constituent voxels, which is a measure of bone heterogeneity. We classified the sites in eight groups, according to gender and location (anterior and posterior regions of the mandible and the maxilla). Based on the one-way ANOVA test and on the Kruskal-Wallis test, we found that significant differences exist between the mean values of CT numbers and the standard deviations of CT numbers. Our study suggests that, under identical conditions, CBCT is able to detect differences in bone density and microstructure. The CBCT scale established here for trabecular bone density and heterogeneity might be useful for pre-operative evaluation of bone quality.
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