6 research outputs found

    Evaluation of linear tomography accuracy in localization of nasal fossa and maxillary sinus

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    Background and Aim: Accurate measurement of bone height and width is essential prior to dental implant placement. The method of surgery as well as, the type and size of implants are determined according to dimensions of the residual bone. The purpose of this study was to evaluate the accuracy of linear tomography in localization of the floor of nasal fossa and maxillary sinus, and to determine the width of maxillary bone at the designated site for implant placement.Materials and Methods: In this test evaluation study, the vertical distances between the alveolar crest and the floor of nasal fossa and the floor of maxillary sinus was measured by the tomographic slices in 12 sites of three dry human skulls. In addition, the width of maxillary bone was measured at the same slices. The skulls were then sectioned through the marked places. Then the radiographic values were compared with the real values of bone sections.Results: After correction of tomographic values by the magnification factor of the unit, the mean absolute measurement error for vertical values at nasal fossa and maxillary sinus area in tomographic slices were 0.28 mm (SD= 0.24) and 1.1 mm (SD= 0.68) respectively. The mean absolute measurement error for maxillary width at the nasal fossa and maxillary sinus area were 0.65 mm (SD= 0.50) and 0.55 mm (SD= 0.45) respectively. 100 % of vertical values at nasal fossa area and 50 % of vertical values at maxillary sinus area were within ± 1 mm error limit. In addition, 50 % of width measurements at nasal fossa area and 83.3 % at maxillary sinus area were within ± 1 mm error limit.Conclusion: The linear tomography is more accurate in height estimation at nasal fossa area and in width estimation at maxillary sinus area. The accuracy of linear tomography in height and width estimation is within acceptable limits at both nasal fossa and maxillary sinus area

    An evaluation of the subtraction photoshop software accuracy to detect minor changes in optical density by radiovisiography

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    Statement of Problem: Subtraction is a newly presented radiography technique to detect minor density"nchanges that are not visible by conventional radiography."nPurpose: The aim of this In-vitro study was to evaluate the efficacy of photoshop subtraction software for"ndetecting minor density changes between two dental images."nMaterials and Methods: In this research, five dried human mandibles were held in fixed position while thin"naluminium sheets were superimposed on each mandible on the 1th and 2nd molar teeth regions."nA reference image, without aluminium sheet placement, was obtained from each mandible subsequently series"nconsist of 20 images with aluminium sheets, ranging from 50p. to "5Q0"x were recorded by radiovisiography"n(RVG) system. Initial images were subtracted from subsequent ones by Photoshop subtraction software. The"ndifference in density between the two images at the 1st and 2nd molar sites was related to the aluminium"nsheets. The optical density of aluminium sheets was determined by densitometer."nResults: In the present study, 6.6% of the optical density changes of the minimum aluminium thickness as"n300u. could be detected by photoshop software software."nConclusion: The findings of this study showed that the accuracy of photoshop subtraction software was equal"nto that of the conventional subtraction softwares. Additionally, the accuracy of this software was proved to be"nsuitable for clinical investigations of small localized changes in alveolar bone

    Centering Ability of F6 SkyTaper and RaCe Rotary Files: A Cone-Beam Computed Tomography Study

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    Background and Aim: Maintaining the original shape and path of the canal is among the most important criteria for optimal root canal preparation. The aim of this study was to compare the centering ability of F6 SkyTaper and RaCe rotary files in mesiobuccal canals of mandibular molars.   Materials and Methods: In this experimental study, 30 mesiobuccal canals of extracted human mandibular molars with 25-30-degree curvature were randomly divided into two experimental groups (n=15) of RaCe and F6 SkyTaper. After mounting of the teeth in a putty mold, the distance between the canal walls and the outer surface of the roots in mesial and distal aspects was measured. The measurements were made at 1, 3 and 7 mm from the apex. Initial glide path in the canals was achieved using a # 15 K-file. Then, the canals in group A were prepared by RaCe rotary file #25/6% while the canals in group B were prepared by F6 Sky Taper rotary file #25/6%. Measurements were repeated and the difference between the two measurements was calculated and compared with the Mann-Whitney U test. Results: The mean centering ability was 0.72 ± 0.62 in the RaCe group and 0.95 ± 1.39 in F6 SkyTaper group. the centrality was better in F6 SkyTaper group (it was closer to 1) but the difference was not statistically significant (P=0.4). Conclusion: Both RaCe and F6 SkyTaper rotary systems partially offset the centrality of the root canal system

    In Vivo Diagnostic Accuracy of Digital Radiography in the Detection of Secondary Caries in Anterior Teeth

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    Background and Aim: Secondary caries are a common challenge for dentists. Many researchers have evaluated the accuracy of digital radiographic systems in the detection of secondary caries and have reported controversial results. Therefore, the aim of this in vivo study was to determine the diagnostic accuracy of digital radiography in the detection of secondary caries in anterior teeth. Materials and Methods: In this diagnostic in vivo study, 34 patients were selected from among the individuals who wished to replace their anterior teeth restorations. The restorations in need of replacement were class III or class IV composite resin restorations which were at least 5 years aged with either a crack in the restoration body or with more than 0.5mm marginal maladaptation or marginal discoloration. Digital radiographs were obtained and were observed randomly by four oral and maxillofacial radiologists. Caries detection was classified using a 5-point Likert scale. Statistics were computed to assess Kappa coefficients. Results: According to the data, observer reliability for PSP sensor was between 0.79 and 0.88 which is an indicator of the high accuracy of PSP sensor. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 90, 77, 86, 85 and 86 % respectively. Conclusion: The results suggest that in vivo digital radiography with PSP sensors is sufficiently accurate in the detection of secondary caries
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