Effect of digital enhancement on the radiographic assessment of vertical root fractures in the presence of different intracanal materials: an in vitro study.

OBJECTIVES: To evaluate the effect of enhancement tools of intraoral digital radiographs on the assessment of vertical root fracture (VRF) and to quantify the resultant image noise. MATERIALS AND METHODS: Thirty single-rooted human teeth (15 control and 15 fractured) were each radiographed in four intracanal conditions: no filling, gutta-percha, metal post, and fiberglass post, totaling 120 original images. Two filters were applied to the original images-Sharpen filter (SF) and Edge Enhancement filter (EE), and brightness and contrast were adjusted in four combinations (B&C1 to 4), resulting in 840 images. Five oral radiologists analyzed the images for VRF detection. Pixel intensity was obtained in two regions from the radiographs. Diagnostic values were calculated and compared by two-way ANOVA, and the SD values of pixel intensity values were compared by one-way ANOVA (α = 0.05). RESULTS: There were no significant differences in accuracy for VRF detection between the experimental groups (p > 0.05). Teeth with metal post presented the lowest sensitivity (p < 0.05) for all experimental conditions, except for SF and EE (p > 0.05). B&C2, B&C3, and B&C4 had higher specificity than SF (p ≤ 0.05) for all intracanal conditions. Analysis of pixel intensity showed that all enhanced images presented statistically significant higher noise compared to those of the original images (p ≤ 0.05). CONCLUSION: Digital enhancement tools in digital radiography increase image noise; however, they can be used without compromising VRF detection. CLINICAL RELEVANCE: The use of digital enhancement does not impair the detection of VRF and, therefore, can be applied for this purpose according to the observer preference.

Assessing pulp stones by cone-beam computed tomography.

OBJECTIVES: The aim of this study was to evaluate the occurrence of pulp stones by cone-beam computed tomography (CBCT) and to correlate their prevalence with patient's gender, location of tooth (right or left of maxillary or mandibular arch), group of teeth, and restorations. MATERIALS AND METHODS: CBCT images of 382 patients randomly selected from the database of the University Oral Radiology Department were retrospectively examined. A total of 2833 tooth images obtained using the i-CAT 3D Imaging System were evaluated. Image analysis was performed with the i-CAT software, and all teeth were evaluated in sagittal, axial, and coronal views. All the measurements were subjected to chi square test, odds ratio, and Fisher's exact tests (p < 0.05). RESULTS: The prevalence of pulp stones was similar between patient's genders and tooth locations. Pulp stones were detected in 31.9% of patients and 9.5% of teeth. Maxillary and mandibular molars were the groups of teeth with the highest frequency of pulp stones. The presence of restorations increased the chance of occurrence of pulp stones by 2.1 times in all teeth examined (p < 0.0001) and by 4.7 times in maxillary teeth (p < 0.0001). CONCLUSIONS: Pulp stones had a high prevalence with molar teeth showing the highest prevalence. The presence of restorations increased the chance of occurrence of these calcifications, specifically in maxillary teeth. CLINICAL RELEVANCE: CBCT provides accurate anatomical details in three dimensions, offering the possibility to view an individual tooth in axial, sagittal, and coronal views. This study performed an investigation of the occurrence of pulp stones by CBCT.

Evaluation of a metal artefact reduction tool on different positions of a metal object in the FOV.

OBJECTIVES: To evaluate the action of a metal artefact reduction (MAR) tool when artefact-generator metal object is at different positions in the field of view (FOV). METHODS: A cylindrical utility wax phantom, with a metal alloy sample inside, was made. The phantom was positioned centrally and peripherally in the FOV for image acquisition, with and without the MAR tool activation. The standard deviation values (image noise levels) from areas around the metal sample and the control area were obtained. The numbers were compared by Student's t-test (α = 0.05). RESULTS: When the tool was activated, a significant difference of image noise was observed for central and peripheral positioning, for both control area (p = 0.0012) and metal area (p = 0.03), and a smaller level of noise was observed for images with phantoms in central positioning. A decrease in image noise with the tool activated was found only in phantoms with the metal object positioned centrally in the FOV. CONCLUSIONS: For the MAR tool to be effective, the artefact-generator object needs to be in the central region of the FOV.

Assessment of three methods of geometric image reconstruction for digital subtraction radiography.

OBJECTIVES: To evaluate three methods of geometric image reconstruction for digital subtraction radiography (DSR). METHODS: Digital periapical radiographs were acquired of 24 teeth with the X-ray tube at 6 different geometric configurations of vertical (V) and horizontal (H) angles: V0°H0°, V0°H10°, V10°H0°, V10°H10°, V20°H0° and V20°H10°. All 144 images were registered in pairs (Group V0°H0° + 1 of the 6 groups) 3 times by using the Emago(®) (Oral Diagnostic Systems, Amsterdam, Netherlands) with manual selection and Regeemy with manual and automatic selections. After geometric reconstruction on the two software applications under different modes of selection, all images were subtracted and the standard deviation of grey values was obtained as a measure of image noise. All measurements were repeated after 15 days to evaluate the method error. Values of image noise were statistically analyzed by one-way ANOVA for differences between methods and between projection angles, followed by Tukey's test at a level of significance of 5%. RESULTS: Significant differences were found between most of the projection angles for the three reconstruction methods. Image subtraction after manual selection-based reconstruction on Regeemy presented the lowest values of image noise, except on group V0°H0°. The groups V10°H0° and V20°H0° were not significantly different between the manual selection-based reconstruction in Regeemy and automatic selection-based reconstruction in Regeemy methods. CONCLUSIONS: The Regeemy software on manual mode revealed better quality of geometric image reconstruction for DSR than the Regeemy on automatic mode and the Emago on manual mode, when the radiographic images were obtained at V and H angles used in the present investigation.