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CONTEXT: Early detection of peri-implant bone defects is highly important to prevent further bone loss and implant failure. AIMS: This study aimed to assess the diagnostic accuracy of three cone-beam computed tomography (CBCT) systems and periapical radiography for detection of fenestration around dental implants. METHODS: Thirty-one titanium implants were placed in the bovine ribs, in which peri-implant fenestration were simulated. Using a round fissure bur, fenestration defects were created in the apical-third region of implants. CBCT and PA radiographs were obtained before and after creating the defects. The results were analyzed using Chi-square test; kappa coefficient; Cochran's Q-test; McNemar's test; and sensitivity, specificity, positive predictive value, and negative predictive value; and receiver operating characteristic curve. RESULTS: A significant agreement was noted between the two observers in the detection of defect-free samples in all imaging systems (P < 0.05). In detection of samples with defects, a significant agreement was observed between the two observers in use of Cranex three-dimensional and NewTom 3G systems (P < 0.05), but the agreement was not significant for detection of defects in use of Promax 3D (P > 0.05). The results showed no significant difference among the four imaging systems in detection of defect-free samples while the difference was significant among the four groups for detection of defects (P < 0.05). NewTom had the highest sensitivity (75.81%) and specificity (100%) for detection of fenestration. CONCLUSIONS: Within the limitations of CBCT systems different kVp used by different systems, artifacts and noises that influences image quality, difference in diagnostic value of different CBCT systems is due to the differences in type of detector and voxel size. In terms of the type of detector, our results showed that NewTom 3G, which has a higher (kVP) than other systems and the highest accuracy for detection of fenestration.
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BACKGROUND AND OBJECTIVES: Image processing and enhancement filters can significantly improve the diagnostic value of digital radiographs. Evidence shows that increasing the contrast and filtering improve the diagnostic accuracy for caries detection. This study sought to assess the diagnostic accuracy of original and enhanced digital radiographs for the detection of approximal and occlusal caries. SUBJECTS AND METHODS: In this experimental study, incipient carious lesions were artificially created on 120 proximal and occlusal surfaces of human extracted permanent molar and premolar teeth. After mounting the teeth in wax, digital radiographs were obtained using photostimulable phosphor plates and enhanced by enhancement filters 1, 2, and 3 with/without denoising. Two oral and maxillofacial radiologists blinded to filtering viewed the radiographs and filled out a chart. A definite diagnosis was made by a pathologist by observing the samples under a stereomicroscope (gold standard). Data were analyzed using SPSS software version 16. Interobserver agreement was calculated using kappa statistics. Chi-square test was used to assess the correlation between qualitative variables. RESULTS: Assessment of sensitivity, specificity, accuracy, positive predictive value, and negative predictive value showed that enhancement filter 2 without denoising was the most efficient and original radiographs (filter free) were the least efficient radiographs for the detection of carious and sound surfaces. Application of filters significantly increased the accuracy of caries detection on digital radiographs. The lowest diagnostic accuracy was noted for the detection of enamel lesions on original radiographs (52%). Enhancement filter 2 plus denoising was the best filter for the detection of these lesions (79.25%). No significant difference was noted among different filters for detection of carious and sound surfaces but enhanced, and original radiographs were significantly different in visualization and detection of caries (P < 0.05). CONCLUSION: Application of enhancement filters, particularly enhancement filter 2 with/without denoising, increases the accuracy of caries detection on digital radiographs.
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INTRODUCTION: The main goal of this ex vivo study was to assess and compare the cellular and electrophysiological effects of two dental biomaterials, white mineral trioxide aggregate (WMTA) and calcium enriched mixture (CEM) cement, on neuronal cell excitability and electrical properties. MATERIALS AND METHODS: A conventional intracellular current clamp technique was used to study the cellular effects of WMTA and CEM on the excitability, firing and the shape of action potential of neuronal soma membrane of F(1) nerve cells. The dental biomaterials were prepared according to the manufacturers' directions and were applied to the bathing media and 0.05 mL of total mixture of each dental material at a distance of 3 mm from the cells. RESULTS: Findings indicated that exposure to both dental biomaterials shifted the irregular high frequency firing type observed in control conditions to a more regular low frequency firing pattern. Neuronal exposure to WMTA, but not CEM, significantly hyperpolarized the cell resting membrane potential. Both treatments significantly influenced the duration and the amplitude of action potentials. Extracellular application of either CEM or WMTA caused a significant increase in the after hyperpolarization (AHP) amplitude and AHP area, but the potentiating effect of WMTA was more effective than CEM. CONCLUSION: Treatment with WMTA or CEM resulted in a profound alteration in the firing behaviour of F(1) cells and changed the AP characteristics. Both dental biomaterials reduced the neuronal activity possibly through enhancement of K(+) outward current. This may possibly explain the positive mechanisms of these biomaterials in regenerative endodontics, though further research is needed for such a conclusion.
