Journal of Dental Medicine

Background and Aim: In recent decades many guidelines has been conducted by radiation protection organizations about radiation protection in dentistry. This study was designed to evaluate the observance of these guidelines in educational clinics of all dental schools in Iran.
Materials and Methods: In this cross-sectional study a questionnaire based on National Radiation Protection guidelines was conducted. The questionnaire consisted of questions about radiation protection principles in dental radiography that is needed for patients and personnel protection and quality control of radiological instruments. The questionnaires were completed by the responsible person of each radiology department of dental schools (18 schools). After gathering the data, the results were compared with radiation protection standards.
Results: There was proper condition in the case of the existence of radiation protection facilities, such as lead apron, thyroid shield and lead impacted walls. However, personnel rarely use these facilities. Usage of high speed films and existence of automatic processor in dental schools was an appreciable point. The main problem was related to the lack of regular quality control programs.
Conclusion: The observance of radiation protection regulations in radiology departments of dental schools was proper. But majority of departments had no regular quality control programs and the use of digital systems in dental radiography was not common.

Background and Aims: Cone beam computed tomography (CBCT) produces high-quality data about diagnosis and periodontal treatment. To date, there is not enough research regarding periodontal bone measurement using CBCT. The aim of this study was to compare the accuracy of CBCT in measuring periodontal defects to that of intraoral radiography and probing methods.
Materials and Methods: Two-hundred and eighteen artificial osseous defects (buccal and lingual infrabony, interproximal, horizontal, crater, dehiscence and fenestration defects) were created on 13 mandibles of dry skulls. The mandibles were put into a plexiglass box full of water to simulate soft tissue. CBCT images, radiographic images taken with parallel technique and direct measurements using a WHO periodontal probe were recorded and compared to a standard reference (digital caliper). Inter and intra observe consistencies were assessed using Intra class correlation coefficient and pearson correlation.
Results: Inter and intra observer consistencies were high for CBCT and probing methods (ICC- Intra class correlation coefficient>88%), but moderate for intraoral radiography (ICC-Intra class correlation coefficient > 54%). There were not any significant differences between observers for all techniques (P>0/05). According to paired T-test analysis, mean difference for CBCT technique (0.01 mm) was lower than that for probing (0.04 mm) and radiography (0.62 mm). CBCT was able to measure all kinds of lesions, but radiography could not measure defects in the buccal and lingual sites.
Conclusion: All three modalities are useful for identifying periodontal defects. Compared to probing and radiography, the CBCT technique has the most accuracy in measuring periodontal defects.

Background and Aims: The evaluation of absorbed dose received by patients could give useful information for radiation risk estimation. This study was performed to compare the entrance skin dose received by patients in cone beam computed tomography (CBCT), conventional and spiral computed tomography (CT).
Materials and Methods: In this experimental study, 81 calibrated TLD chips were used. the TLD chips were placed on facial, thyroid and end of sternum skin surface in patients referred for CT of the paranasal sinuses (3 TLD chips for each area) to estimate the absorbed dose received by central part of radiation field, thyroid and out of field areas, respectively. The data were analyzed using one-way ANOVA and Tukey tests.
Results: The dose delivered to the center of irradiated field was about 0.79±0.09 mGy in CBCT technique compared with 16.31±3.71 and 18.84±4.12 mGy for spiral and conventional CT, respectively. The received dose by the out of field areas was about 54 percent of central area dose. There was statistical significant relationship between the imaging modalities and absorbed dose received by patients (P=0.016). The least absorbed dose was for CBCT and the greatest dose was for conventional CT imaging technique.
Conclusion: The dose delivered to central area of irradiated field in conventional and spiral CT imaging modalities was about 24 times greater than of that in CBCT. Also, the highest received dose was for central area of radiated field and the lowest dose was for the out of field areas.