Assessing the Accuracy of Caries Diagnosis in Bitewing Radiographs Using Different Reproduction Media.

STATEMENT OF THE PROBLEM: After introducing digital radiography, practitioners started reading radiographs from computer monitors; however, many still prefer hard-copy radiographs. PURPOSE: This study aimed to assess the possible superiority of either type of radiograph recording media (computer monitor, film, or paper) in diagnosis and perception of the depth of the cariogenic lesions. MATERIALS AND METHOD: Twenty digital bitewing radiographs, obtained from 200 posterior extracted teeth, were displayed on an LG monitor and printed on paper and film using Kodak printers. Two observers independently measured lesions depth on the images. Serial sections of teeth were obtained and the sections were evaluated by a stereomicroscope to determine the actual depth of cariogenic lesions. The efficacy of the each medium was assessed by determining its specificity and sensitivity in comparison with those of histological images. Weighted kappa coefficients and the ROC analysis were used for the statistical analysis. RESULTS: Strong intra- and inter-observer agreements (0.818 to 0.958, 0.77 to 0.85) were found for all detection methods. The highest Az value was obtained with the monitor-displayed images (Az: 0.879); however, differences between detection methods were not statistically significant (p> 0.05). CONCLUSION: Monitor-displayed bitewing radiographs, paper, and film prints used in our study performed similarly in the detection of proximal caries.

Influence of Head Position on the CBCT Accuracy in Assessment of the Proximity of the Root Apices to the Inferior Alveolar Canal.

STATEMENT OF THE PROBLEM: The most important risk factor for inferior alveolar nerve (IAN) damage is the proximity of the mandibular root apices to the alveolar canal. Failure to position the patient's head at standardized orientation during cone beam computed tomography (CBCT) scans might adversely affect the relative position of the alveolar canal and mandibular root apices with subsequent treatment failure. PURPOSE: The purpose of the present study was to investigate the influence of the orientations of the skull during the scanning procedure on the accuracy of CBCT images in determining the positional relationship of the mandibular tooth apices to the alveolar canal. MATERIALS AND METHOD: CBCT scans of 7 human dry skulls were obtained by using NewTom VGi CBCT in standard, tilt, flexion, extension and rotation positions of the head. The shortest radiographic distance between the mandibular tooth apices and the IAN canal of 20 points were measured on cross sectional images of CBCT in all position scans. A sample t-test was used to compare the measurements at different head position with the standard position values. RESULTS: Significant differences were found in the measurements of normal and tilt orientations. However, there was no statistically significant difference between the measurements in standard position and other deviated positions. The mean errors in all head positions were less than 0.5mm. CONCLUSION: Alteration of patient head positioning during CBCT scanning does not affect the relative position of the IAN and the apices of posterior teeth.

Comparison of cone-beam computed tomography and osteometric examination in preoperative assessment of the proximity of the mandibular canal to the apices of the teeth.

The risk of postoperative neurosensory impairment after extraction of a third molar will be greater if the inferior alveolar nerve is in close proximity to the apices of the root. Precise preoperative evaluation of the relative positions of the nerve and the mandibular apices is important to protect the nerve from mechanical irritation. The aim of this study was to assess the accuracy of cone-beam computed tomography (CT) in the identification of the positional relations of the mandibular third molar and the inferior alveolar canal using Rood's criteria. Panoramic images of 10 dry hemimandibles were obtained, and 20 teeth each with one of Rood's criteria indicating close relations to the mandibular canal were selected. Cone-beam CT images of the selected points were obtained. The closest distance between the apex of the root and the inferior alveolar canal was measured on cross-sectional cone-beam CT images. The same measurements were made on the corresponding osteometric sections with digital callipers. The intra-class correlation coefficient (ICC) was used to measure the consistency between the two measurements as the reference method, and showed that there was a high level of inter-rater agreement (r>0.90). The mean (SD) deviation of cone-beam CT measurements from the gold standard osteometric measurements was small at 0.30 (0.24). There were almost perfect matches between cone-beam CT and gold standard measurements. Cone-beam CT is an accurate technique to measure the proximity of the mandibular apices to the alveolar nerve.

Effect of Cortical Bone Thickness on Detection of Intraosseous Lesions by Ultrasonography.

Background. Usefulness of ultrasound (US) in detection of intrabony lesions has been showed. A cortical bone perforation or a very thin and intact cortical bone is prerequisite for this purpose. Objective. The current in vitro study was aimed at measuring the cut-off thickness of the overlying cortical bone which allows ultrasonic assessment of bony defects. Materials and Methods. 20 bovine scapula blocks were obtained. Samples were numbered from 1 to 20. In each sample, 5 artificial lesions were made. The lesions were made in order to increase the overlying bone thickness, from 0.1 mm in the first sample to 2 mm in the last one (with 0.1 mm interval). After that, the samples underwent ultrasound examinations by two practicing radiologists. Results. All five lesions in samples numbered 1 to 11 were detected as hypoechoic area. Cortical bone thickness more than 1.1 mm resulted in a failure in the detection of central lesions. Conclusion. We can conclude that neither bony perforation nor very thin cortical bones are needed to consider US to be an effective imaging technique in the evaluation of bony lesion.