Abstract
 Comparison of the diagnostic validity and accuracy of the spiral tomography and spiral C.T. scan in maxillary implant assessment
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 Dr. Shahab S.,1 Dr. Raftari D.,2 Dr. Namjouy-Nik S.3
 1Assistant Professor, Department of Oral and Maxillofacial Radiology. Shahed Dental school, Tehran, Iran . 2Dentist, Private Practice, Tehran, Iran. 3 PhD of Implant and Assistant professor, Department of Oral and Maxillofacial Surgery. Shahed Dental school,Tehran, Iran.
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 Abstract
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 Background & Aim: The accuracy and validity of CT scan images have been established by various investigators. However, there are controversies about the accuracy and validity of tomography techniques. The purpose of this study was to compare the accuracy and validity of diagnostic measurements made out of spiral tomography and spiral CT of human maxilla.
 Materials & Methods: Eight partially or fully edentulous dry human maxillae were used in this invitro investigation. A total of 50 edentulous areas were identified as potential implant sites. These locations were composed of 8 sites in midline, 14 in canine, 15 in premolar and 13 sites in molar areas.
 The spiral tomographies as well as spiral CTs were taken for the selected sites. The following bone parameters were measured in each maxilla:
 I) Vertical distance between the surface of alveolar bone and floor of nasal cavity or maxillary sinuses (Height).
 II) Buccopalatal alveolar ridge distance at the mid-height section(Width).
 Tomography measurements were compared with that of CT images in order to determine the measurements precision. To investigate the validity, the method of Inter-device Inter-observer and test of Intra-class Correlation Coefficient of One-Way Random Effects model was applied.
 Results: Only 6 out of 100 measurements of tomography showed more than 1mm difference with CT images. The accuracy of tomograms in measuring height and width of alveolar bone was 96% and 92% respectively. This accuracy was 100% in midline, 93.3% in canine, 86.7% in premolar and 100% in molar area. The mean difference was 0.66mm
 Between measurements of these two techniques. The reliability of tomograms was %96.
 Conclusion: This investigation demonstrated that spiral tomography is highly accurate in cross sectional imaging of the jaw bones. The validity and reliability of spiral tomography technique is good and acceptable .Therefore, we can use tomography for jaw bones imaging in potential implant cases with high level of confidence.
 Key words: Dental implant - Spiral tomography- Spiral CT scan - Maxilla.
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 Corresponding Author: Dr. Shahab S., Department of Oral and Maxillofacial Radiology. Shahed Dental school, Tehran, Iran .
 e.mail: sh.shahab@mailcity.com
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