The efficacy of the reverse contrast mode in digital radiography for the detection of proximal dentinal caries

PURPOSE: This study evaluated the diagnostic accuracy of the reverse contrast mode in intraoral digital radiography for the detection of proximal dentinal caries, in comparison with the original digital radiographs. MATERIALS AND METHODS: Eighty extracted premolars with no clinically apparent caries were selected, and digital radiographs of them were taken separately in standard conditions. Four observers examined the original radiographs and the same radiographs in the reverse contrast mode with the goal of identifying proximal dentinal caries. Microscopic sections 5 microm in thickness were prepared from the teeth in the mesiodistal direction. Four slides prepared from each sample used as the diagnostic gold standard. The data were analyzed using SPSS (alpha=0.05). RESULTS: Our results showed that the original radiographs in order to identify proximal dentinal caries had the following values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, respectively: 72.5%, 90%, 87.2%, 76.5%, and 80.9%. For the reverse contrast mode, however, the corresponding values were 63.1%, 89.4%, 87.1%, 73.5%, and 78.8%, respectively. The sensitivity of original digital radiograph for detecting proximal dentinal caries was significantly higher than that of reverse contrast mode (p0.05). CONCLUSION: The sensitivity of the original digital radiograph for detecting proximal dentinal caries was significantly higher than that of the reversed contrast images. However, no statistically significant differences were found between these techniques regarding specificity, positive predictive value, negative predictive value, or accuracy.

Expression of p27 protein in oral and esophageal squamous cell carcinoma

Squamous cell carcinoma [SCC] is the most common malignant tumor of oral cavity [O] and esophagus [E]. P27 protein has a significant role in biological behavior of the tumors. The purpose of this study was to determine the frequency of P27 expression in OSCC and ESCC. Forty paraffin embedded blocks of OSCC and ESCC were collected and clinic pathological data were recorded in this descriptive study. Immunohistochemical staining [IHC] was done for P27 [Kipl] and Labeling Index [percent of positive cells in 10HPF] was calculated and then cases classified in to low [LI<25%] and high [LI>25%] expressions. Statistical analysis was performed by SPSS 16 using Fisher's exact and Mann-Whitney tests. Twenty-four cases [60%] were male and 16 cases [40%] were female. The mean age was 65.3+14.3. Twenty five percent of ESCCs and 10% of OSCCs showed high expression of P27. Seventy five percent of ESCC and 90% off OSCC showed low expression and there was no significant difference among OSCCs and ESCCs [P>0.05]. There were no significant correlations between age, sex, grade or size of the tumors and P27 expression in OSCCs and ESCCs. Low expression of P27 was found in most of ESCC and OSCC cases