Influence of exposure parameters on the detection of simulated root fractures in the presence of various intracanal materials.

AIM: To investigate how the exposure parameters used when producing CBCT scans affect diagnostic accuracy when detecting simulated vertical root fractures and how various filling materials affect image quality. METHODOLOGY: A total of 160 extracted single-rooted human teeth were divided into four groups based on the materials within the root canals: unrestored, gutta-percha, metallic post and fibreglass post. Half of the sample of each group was selected for the induction of vertical root fractures. Each tooth was placed in an empty socket of a dry skull which was scanned on a CBCT unit (9000 3D scanner; Kodak Dental Systems, Carestream Health, Rochester, NY, USA) using the following exposure parameters: 74 kV/12 mA; 74 kV/10 mA; 74 kV/8 mA; 74 kV/6.3 mA; 70 kV/12 mA; 70 kV/10 mA; 70 kV/8 mA; 70 kV/6.3 mA. Two observers assessed all images using a 5-point confidence scale for fracture detection and a 4-point score for the presence of artefacts. Sensitivity, specificity, accuracy and area under ROC curve were compared by two-way anova and Tukey's test. Artefact formation was evaluated by descriptive statistics. RESULTS: There were no significant differences in the sensitivity (P = 0.370), specificity (P = 0.660), accuracy (P = 0.084) and area under the ROC curve (P = 0.674) values amongst the various exposure parameters within the same group. There were some significant differences when the groups were compared for each intracanal material. The sensitivity and accuracy of the group containing metallic posts were significantly lower than the unrestored and fibreglass post groups (P ≤ 0.017). CONCLUSION: The variations in exposure parameters did not interfere with the diagnosis of vertical root fractures, independent of the root canal restorative status. Metallic posts were associated with greater artefact formation and compromised the diagnostic performance. It is possible to decrease the kVp/mA settings to reduce the probability of biological effects due to radiation, without losing diagnostic accuracy.

Correlation between temporomandibular joint morphology and disc displacement by MRI.

OBJECTIVES: The aim was to evaluate the morphology of the temporomandibular joint's (TMJs) disc and condyle as well as its correlation with disc displacement, using MRI. METHODS: 190 TMJs were retrospectively analysed. The condyle morphology of each TMJ was evaluated by two observers using both axial and coronal views, as were their disc morphology and displacement, using sagittal view. Condyle morphology was classified as flat, convex, angled or rounded in the coronal sections and as anterior side flat/posterior side convex, biconvex, anterior side concave/posterior side convex, flat or biconcave in the axial view. Disc morphology was determined as biconcave, biplanar, biconvex, hemiconvex or folded. χ2, Fisher exact and Bonferroni correction tests were used to evaluate the data. ANOVA followed by post hoc Tukey's test was used to evaluate the interaction between age and disc displacement. RESULTS: Anterior disc displacement with reduction; convex condyle morphology in the coronal view; anterior side concave/posterior side convex morphology in the axial view; and biconcave discs were found to be the most prevalent findings. An association was observed between disc morphology and disc displacement (p<0.001). No correlation between condyle morphology and TMJ disc displacement was found (p=0.291 for axial and p=0.14 for coronal views). CONCLUSIONS: The results of this study suggest that TMJ disc morphology is associated with disc displacement.

Evaluation of panoramic radiomorphometric indices related to low bone density in sickle cell disease.

SUMMARY: In sickle cell disease, erythroid hyperplasia causes trabecular destruction leading to low bone density. This condition could be suspected by the radiomorphometric indices and your diagnosis becomes relevant in a multidisciplinary context of health care for sickle cell subjects, providing prognostics and contributing to determine adequate therapeutic and preventive actions. INTRODUCTION: The aim of this study was to assess the risk of low bone density in subjects with sickle cell disease (SCD) through analysis of panoramic radiographic exams by radiomorphometric indices. METHODS: Seventy-eight Brazilian subjects with SCD took part in this study and were subdivided into four groups: (I) 31 SCD subjects aged under 40 years; (II) 13 SCD subjects aged 40 years or more; (III) 12 normal subjects aged under 40 years; and (IV) 22 normal subjects aged 40 years or more. In the panoramic radiographs, the mandibular cortical index (MCI) classification, increased spacing of the trabecular bone, panoramic mandibular index (PMI), and mental index (MI) were evaluated. Exact Fisher's test was used to compare age between the different groups. Descriptive analysis of the data was performed to evaluate the simple visual estimation of low bone density (increased bone trabecular space and MCI), and a one-way analysis of variance (Bonferroni criteria) was used to compare the means of the quantitative indices (PMI and MI). The significance level was p < 0.05. RESULTS: In the MCI classification, C2 was more prevalent, especially in groups I and IV. Increased spacing of the trabecular bone was more frequent in groups I and II. MI did not show a statistically significant difference among the groups. PMI showed a statistically significant difference only between groups III and IV. CONCLUSIONS: The radiomorphometric indices applied in the present study can be used on panoramic radiographs to detect the presence of low bone density in SCD subjects.