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OBJECTIVES: The aim of this study was to evaluate the accuracy of linear measurements obtained with dental cone beam CT (CBCT) and multislice CT (MSCT) by altering radiation doses using pre-operative planning of the placement of oral implants as a model. METHODS: A human cadaver mandible was examined in two edentulous areas and one dentate area using CBCT and MSCT. The mandible was examined both dry and immersed in sucrose solution isointense with soft tissue. Two readers measured four linear distances twice from each section. The mandible was cut into 4 mm thick slices at three marked places. These slices were microradiographed and used as the gold standard for measurements from each section. RESULTS: The intraclass correlations between the intra- and interobserver readings obtained with the different methods showed almost perfect matches. The measurement error (ME) showed significant differences between the methods studied (P = 0.022): the mean ME was 4.7% for CBCT and 8.8% for MSCT of the dry mandible, 2.3% and 6.6%, respectively, for the mandible immersed in sucrose solution and 5.4% for low-dose MSCT. Lowering the MSCT radiation dose to less than a quarter of its conventional original value did not significantly affect the ME. CONCLUSIONS: CBCT is a reliable tool for implant-planning measurements when compared with MSCT. In this study, a considerable radiation dose reduction could be achieved with low-dose MSCT examinations without a major loss of measurement accuracy.
Suomalainen et al. (Tue,) studied this question.