RESUMEN
It is crucial to verify the relationship between root apices and maxillary sinus floor in some surgical procedures like extraction and implant placement or in orthodontic movements like intrusion. Protrusion of roots into the sinus increases the risk of post extraction pneumatization which in turn decreases the available bone at the implant or denture sites. The aim of this study was to determine the panoramic radiology accuracy for defining the relationship between posterior root apices and the maxillary sinus floor by Cone Beam CT [CBCT]. Paired panoramic radiographs and CBCT images of 117 subjects were examined. 452 posterior maxillary roots including second premolar, first and second molar were classified by the means of the relationship with maxillary sinus floor. CBCT was used as Gold standard method, and the agreement of panoramic findings with CBCT was examined statistically. Data were analyzed using Chi-square and Multiple logistic regressions. Agreement of the panoramic and CBCT results were seen in 57.7% of all cases. Roots which had no contacts with the sinus floor [class 0] showed a high agreement of 89.5% between two imaging techniques. Roots in contact with sinus floor [class 1] showed 58.8 % and cases with root protrusion into sinus cavity [class 3, 4] showed 50% of agreement [P<0.001]. Also in 36% of cases with no protrusion into the sinus cavity [class 0, 1, 2], panoramic showed protrusion. The agreement for the premolar was higher than molars [P<0.001]. The majority of roots which their images were projected on the sinus cavity had no vertical protrusion in CBCT cuts. Considering the results, in these cases CBCT can be recommended
RESUMEN
Bone density is frequently used in medical diagnosis and research. The current methods for determining bone density are expensive and not easily available in dental clinics. The aim of this study was to design and evaluate the accuracy of a digital method for hard tissue densitometry which could be applied on personal computers. An aluminum step wedge was constructed. 50 E-speed Kodak films were exposed. Exposure time varied from 0.05[s] to 0.5[s] with 0.05[s] interval. Films were developed with automatic developer and fixer and digitized with 1240U photo Epson scanner. Images were cropped at 10x10mm size with Microsoft Office Picture Manager. By running the algorithm designed in MATLAB software, the mean pixel value of pictures was calculated. Finding of this study showed that by increasing the exposure time, the mean pixel value was decreased and at step 12,[a] significant discrimination was seen between the two subsequent times [P<0.001]. By increasing the thickness of object, algorithm could define the density changes from step 4 in 0.3[s] and 5 in 0.5[s], and it could determine the differences in the mean pixel value between the same steps of 0.3[s] and 0.5[s] from step 4. By increasing the object thickness and exposure time, the accuracy of the algorithm for recognizing changes in density was increased. This software was able to determine the radiographic density changes of aluminum step wedge with at least 4mm thickness at exposure time of 0.3[s] and 5 mm at 0.5[s]
RESUMEN
Assessment of skeletal maturity is an integral part of interceptive diagnosis and treatment planning. The present method of skeletal maturity assessment like handwrist or cervical vertebrae radiographies are expensive,require elaborate equipment and account for high radiation exposure, especially for growing children. This study tried to consider the value of the 2nd primary molar in growth stage. 40 samples aged 8-13 were tested by their panoramic and handwrist radiographs. there was a coincidence between presence calcified sesamoid and 2nd primary molar as the last tooth. The result showed that it could be a reliable index to predict the growth stage in 1st visit without radiography