الفهرس 
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Abstract
Cone beam Computed Tomography (CBCT) which recently is being used in dentistry, anatomic structure of the teeth and the mouth can be observed in any section and plane desired in a 3-D form. Thus, considerable advantage and conve¬nience is obtained in diagnosis of occurred root fractures because of dental injuries. Axial, coronal, sagittal and cross-sectional images can be obtained from the data provided by CBCT devices as a result, it is now possible to identify in a more detailed and accurate manner fractures which are diagnosed or otherwise by traditional radiographies.
High-density objects have been shown to cause artifacts that interfere with the diagnostic quality of cone beam CT (CBCT) images. The examination of high-density bodies (gutta-percha and metallic post) shows strong beam hardening and scattering effect artifacts that lead to images unsuitable for diagnostic purposes.
This study was performed for assessment the accuracy of CBCT in detection of horizontal root fracture by alternation of exposure parameters in endodontic and non-endodontic treated teeth.
54 single-rooted human teeth were selected then inspected by trans-illumination for the absence of root fracture, and by conventional periapical radiographs to observe root canal anatomy. Teeth with caries extending to the root, restorations, pulp calcifications, root resorption or root fracture were excluded.
Finally each tooth assigned and divided into six groups: Nine teeth without both endodontic treatment and root fracture. Nine teeth without endodontic treatment but with root fracture. Nine teeth with obturation with guttapecha only. Nine teeth with obturation with gutta-percha and with root fracture. Nine teeth with obturation with gutta-percha and metal post but without root fracture. Nine teeth with obturation with guttaperhca, metal post and root fracture. Each 3 teeth were mounted separately in a blocks that were made from silicon impression putty. Then the blocks were placed in a fine plastic cylinder containing water to simulate soft tissue (phantom). The phantom was placed on the chin rest of CBCT unit. The teeth were imaged by centering the block in a smallest field-of-view FOV (H × D) 50 × 50 mm.
By changing in exposure parameters: (5 mA) with standardized resolution (L5), (5 mA) with high resolution (H5), (10 mA) with standardized resolution (L10) and (10 mA) with high resolution (H10). We produce 216 evaluations detected by three radiologists.
This study confirmed that there is no significant difference to detect HRF by different parameters of CBCT, and Standardized resolution with (5 mA) is the most specific parameter to detect HRFs in endodontic treated teeth.