A comparison of tomography's accuracy between Spiral Cranex Tome and Linear ProMax for evaluating the quantity of bone in posterior of maxilla

An accurate imaging technique has an important role in implantology. Presence of sinus in the posterior maxilla is a limiting factor for implant insertion in this area. Therefore it is necessary to evaluate the relationship between alveolar ridge and sinus. The aim of the present in vitro study was to compare the accuracy of Cranex Tome Spiral and ProMax linear tomography to assess bone quality for the preoperative planning of implants in the posterior maxilla. Tomographs were taken from 3 dry human skulls using both units. Three sites were selected in each side of posterior maxilla and marked with orthodontic wires meaning a total of 24 sites (12 sites for each unit). Bone height and width were measured first on the tomography and then on the skulls after sectioning. In order to compare the measurement values between both units and to compare them with the values obtained from gold the Intraclass Correlation Coefficient of reliability (ICC) was used. The minimum Intraclass correlation coefficient of reliability was 0.569 in two times measurements of width for ProMax, and the maximum of this coefficient was 0.950 in two times measurements of height for Spiral. The mean difference between the real measurements and the height measurements of both units were less than 0.3 mm and for the width measurements were less than 0.5 mm of the real measurements. This study showed in both units, the height measurements were more accurate than the width measurements and all the measurements by Spiral were more valid then those of ProMax. Generally quantitative accuracy of Spiral unit was found to be higher than ProMax unit. Both units proved to be sufficient for quantity measurements. Adjustment an individual imaging plane for each site of tomography increases the accuracy. The most distal sites of Spiral unit may need separate adjustment other than manufacturer demands.