الفهرس 
AcknowledgmentsOnly 14 pages are availabe for public view
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Abstract
Correct assessment of the bone condition is essential for the diagnosis, treatment planning and prognosis of periodontal disease. Information derived from probing the gingival tissues in association with diagnostic imaging provides guidelines for assessing the alveolar bone height and checking for the presence of bone defects. Radiography plays an important adjunctive role in periodontal diagnosis, primarily by providing information regarding the amount and type of damage to the alveolar bone and in addition makes it possible to distinguish the pattern of bone resorption. Among two-dimensional radiographic diagnosis methods, periapical radiographs are the most suitable because they are easily acquired, cheap and provide high resolution images. However, this method is limited by overlapping anatomical structures, lack of 3- dimensional information and by underestimating the size and occurrence of bone defects. This often hinders a true distinction between the buccal and lingual cortical plate making it difficult to obtain an accurate evaluation of alveolar bone loss. Digital images, although decreasing the radiation dose than conventional radiography and improving diagnostic interpretation, are still two-dimensional images that also suffer from overlapping of buccal and lingual structures which may interfere with accurate evaluation of alveolar bone loss. CBCT is a recently developed imaging modality providing a lower cost and a lower radiation alternative to conventional CT. CBCT scanners are specifically designed for imaging the hard tissues of the head and neck. Although CBCT has been largely used in different applications, CBCT is still underused for periodontal diagnosis. 146 Therefore, the aim of this study was to assess and to compare the diagnostic validity of CBCT in relation to digital intraoral radiography in the evaluation of alveolar bone loss. In this study, a total of 25 patients diagnosed with periodontitis were evaluated clinically, by digital periapical radiography and by CBCT. All three techniques rated similarly in measuring the alveolar crest height (CEJ-AV) in areas where there was no alveolar bone loss. Regarding the depth of the defects (CEJ- deepest point of the defect), a statistically significant difference was found between the clinical, digital intraoral and CBCT measurements. The greatest differences in the measurements between the used modalities were obtained in the maxillary posterior region and were smallest in the mandibular posterior region. CBCT and intraoral digital radiography were also different in determining the type of defect whether horizontal or vertical in both maxillary and mandibular posterior region although the results were similar in the anterior region. In general, CBCT showed higher prevalence in detecting vertical defects than digital radiography. When the angle of the vertical defects was measured and compared for both radiographic techniques, this study showed that the CBCT showed higher mean angle measurements than digital modality in upper anterior and lower anterior teeth. For furcation involvement measurements, a statistically significant difference between clinical and CBCT was found in maxillary molars. CBCT showed lower prevalence of Grade I while CBCT showed higher prevalence of Grade II and Grade III. In addition, axial CBCT slices made parallel to the occlusal plane allowed for good visualization of the morphology of the vertical periodontal defects. This allowed for the classification of vertical defects into1-wall, 2-wall, and 3-wall and combined bone defects. Finally, CBCT enabled for better estimation of combined periodontic-endodontic lesions.