Introduction: It is universally accepted that the posteroanterior skull radiograph shows a lower degree of distortion than other radiographic images, so that measurements on it are considered reliable. Objective: To determine the percentage of distortion in the different facial regions of the postero-anterior skull radiograph. Methods: Thirty human skulls with their jaws were divided by three horizontal and four vertical planes into fifteen quadrants; there were ten in the skull and five in the jaw. On each of them a steel wire was placed in vertical and horizontal positions and their length (actual measurement) was measured. Each set was X-rayed in posteroanterior projection and the length of the wires was measured in the image (radiographic measurement). Results: It was not possible to measure in the lateral quadrants of the skull. The horizontal measurement in the right and left lower intermediate quadrants of the skull and in the intermediate and lateral quadrants of both sides of the mandible is not reliable; in the median quadrant of the mandible it is minimized; in the right and left upper intermediate and median quadrants of the skull and in the median of the mandible it is magnified. Vertical measurements in all quadrants are reliable; in the right and left upper intermediate and left upper and middle quadrants of the skull and in the right and left middle and lateral quadrants of the mandible it is magnified; in the lower intermediate and upper and lower middle quadrants of the skull and median of the mandible it is minimized. The least distortion for both measurements occurs in the upper median quadrant of the skull. Percentages of distortion are reported for each quadrant. Conclusions: Distortion is present in the posteroanterior skull radiograph and varies from one region of the face to another.

Introduction: Periodontal disease affects more than half of the population in Colombia and is estimated to be one of the leading causes of oral morbidity. Diagnostic aids that allow the evaluation of its extension and severity are of importance since this will provide reliable tools to quantify the severity of the problem. Objective: To determine the inter-examiner agreement for the detection of radiographic findings in patients with localized chronic periodontitis using conventional periapical radiography. Methods: Study of diagnostic tests including patients with localized chronic periodontitis, the tooth with the worst clinical insertion level and a single conventional radiograph per dental organ using parallelism technique. The radiographic evaluations were performed by two independent and blinded evaluators for the findings: lamina dura, bone defects and type of defect. The agreement obtained was estimated through Cohen’s Kappa. Results: A total of 125 radiographs were taken. The mean age was 38.8 ± 9.9, and 61.6% were women. Concordance for lamina dura was 0.08 (95% CI: -0.04–0.21), bone defects 1.00 (95% CI: 1.00–1.00); type of defect present 0.31 (95% CI: 0.29–0.38). Conclusions: Concordance was evaluated as null, almost perfect and acceptable for the findings lamina dura, presence of bone defects and type of defect respectively. For some findings and given the importance of the diagnostic and therapeutic processes, more accurate evaluations are needed which would result in a higher degree of agreement.

Objective: To determine the presence of bacteria by means of microbiological analysis on the surfaces contacted by the operator during the taking and processing of intraoral radiographs at different times of the day in the Oral Radiology Service of the UPCH. Materials and methods: Nine surfaces of the oral radiology service were sampled. The samples were taken at two times by the same investigator; at the beginning and the end of the activities in the service, the surfaces were swabbed with Trypticase Soy Broth (TSB). The samples were inoculated and incubated in three culture media (Plate Count Agar, Lamb’s Blood Agar and Cetrimide Agar). Then the respective Colony Forming Unit (CFU) count was performed and Gram staining was also performed. Results: A high concentration of bacteria (4180 CFU/mL) and fungi was found in the oral radiology service. Gram-positive cocci were the most frequently found microorganisms and gram-negative bacilli were less frequently found. Conclusions: There is a high contamination of bacteria in the oral radiology service. When the activities are completed, the number of bacteria decreases, but the variety of bacteria increases.