Is the assessment of the mandibular molar danger zone affected by field of view and voxel size in cone beam computed tomography examinations?

OBJECTIVE: To verify if assessment of the danger zone (DZ) in the mesial root of mandibular molars is affected by field of view (FOV) and voxel sizes in cone beam computed tomography (CBCT) scans. STUDY DESIGN: Forty mandibular molars were scanned by micro-computed tomography, creating the reference standard. The teeth were then submitted for CBCT scans with FOVs of 10 × 5.5 cm and 5 × 5.5 cm and voxel sizes of 0.4, 0.2, 0.15, and 0.075 mm3. The smallest dentin thickness in the DZ from the mesiobuccal and mesiolingual canals was measured at 2, 4, and 6 mm apical to the root furcation. Descriptive statistics, paired t-tests, and intraclass correlation coefficients were used for statistical analysis with significance established at P < .05. RESULTS: All CBCT measurements overestimated the DZ dentin thickness (P < .001) compared to the reference standard. The greatest overestimation occurred in the 5 × 5.5 cm FOV with 0.4 mm3 voxels (P = .007). Dentin thickness measured with the 5 × 5.5 cm FOV and 0.075 mm3 voxels was significantly smaller and produced the best ICC value with the reference standard (0.936). CONCLUSIONS: CBCT overestimates the dentin thickness of the DZ regardless of FOV and voxel sizes. The 5 × 5.5 cm FOV showed the best performance with the 0.075 mm3 voxel size, but it performed poorly with 0.4 mm3 voxels.

Assessment of the Metal Artifact Reduction Tool for the Detection of Root Isthmus in Mandibular Molars with Intraradicular Posts in Cone-beam Computed Tomographic Scans.

INTRODUCTION: This study evaluated the performance of the metal artifact reduction (MAR) tool in cone-beam computed tomographic scans using different fields of view (FOVs) in the detection of a root isthmus in mandibular molars with intraradicular posts. METHODS: Twenty-eight teeth were scanned by micro-computed tomographic imaging (gold standard images). Thereafter, specimens were allocated into the following groups: gutta-percha (teeth without posts, n = 10), a prefabricated metal post (n = 9), and a fiberglass post (n = 9). Cone-beam computed tomographic scans were taken using 8 acquisition protocols, varying the size of the FOV (10 × 5.5 cm and 5 × 5.5 cm) and the MAR tool (disabled, low, normal, and high modes). A root isthmus was evaluated considering a 5-point scale. Data were analyzed considering a 5% significance level. RESULTS: Intra- and interexaminer agreement varied from moderate to substantial. The frequency of correct diagnosis varied significantly in all groups regardless of the image acquisition protocol selected (P < .05). In the gutta-percha group, there was no difference in the accuracy, sensitivity, and specificity values between the tested protocols. In the metal and fiberglass post groups, the accuracy values were higher with the "disabled" and "low" modes of the MAR tool regardless of the FOV size. This was also observed for the sensitivity values in the metal post group (P < .05). CONCLUSIONS: The size of the FOV did not affect the performance of the MAR tool in the diagnosis of a root isthmus in molars with intraradicular posts. Our findings suggest that the use of the tool in the "normal" and "high" modes is contraindicated for this purpose.

Demographic characteristics, aetiology, and assessment of treatment options in leukocytoclastic vasculitis.

INTRODUCTION: Vasculitides are a heterogeneous group of diseases characterized by inflammation of the blood vessel walls. Etiological factors include infections, drugs, connective tissue diseases, and malignancies. AIM: To examine the demographic characteristics, etiological factors, and treatment options in 75 patients with leukocytoclastic vasculitis. MATERIAL AND METHODS: The study included 75 patients diagnosed with leukocytoclastic vasculitis at our clinic. The patients' medical records were reviewed to determine their age, sex, presence of systemic symptoms, possible etiological factors, laboratory results, types of cutaneous lesions, locations of the lesions, treatment options, and disease course. RESULTS: There were 43 women and 32 men. Cutaneous lesions affected only the lower limbs in 60 of the 75 patients (80%) and usually presented as palpable purpura (64%, n = 48). Arthralgia (26.7%, n = 20) was the most frequent extracutaneous symptom. Of the patients with secondary vasculitis, the most common causes were infections and drugs. The mean age of the patients with Henoch-Schönlein purpura was 26.8 years. There was no significant association between age and renal, gastrointestinal, or joint involvement. CONCLUSIONS: The most common form of vasculitis in our study was cutaneous leukocytoclastic vasculitis. In most of the patients it appeared to be idiopathic. Among drugs, antibiotics were the most common etiological factor. In 4 patients, the cutaneous leukocytoclastic vasculitis behaved like the paraneoplastic syndrome.

Assessment of recurrence rates in papillary thyroid microcarcinoma patients with and without histopathological risk factors after radioiodine ablation treatment.

AIM: We aimed to assess the recurrence rates of papillary thyroid microcarcinoma in patients with and without histopathological risk factors after radioiodine (RAI) ablation treatment. MATERIALS AND METHODS: A total of 357 papillary thyroid microcarcinoma patients who were referred to Ankara University Medical School, Department of Nuclear Medicine for RAI ablation treatment after total or near-total thyroidectomy were included in the study. All patients received RAI ablation treatment 4-6 weeks after surgery. After RAI ablation, patients were monitored every 3 months within the first 6 months and then every year. RESULTS: During follow-up, sixth-month iodine-131 (I-131) whole-body scans showed successful ablation in 333 (93.3%) patients. However, one (0.2%) patient had a focal lung uptake on the sixth-month I-131 whole-body scan, although the postablative scan gave no evidence of lung metastasis. Lung metastasis of this patient was treated with a second dose of RAI. The mean follow-up period was 124 (min-max: 6-216) months. No recurrence was detected in 344 (96.3%) patients during the follow-up period. However, in 13 (3.6%) patients, new recurrence or metastasis had developed. Lymph node metastasis was detected using fluorine-18 flourodeoxyglucose PET/computed tomography in four and using neck ultrasound in eight of them. The metastasis rates of patients with papillary microcarcinoma at a single focus with no thyroid capsule or lymphovascular invasion (n=268) and those of patients with thyroid capsule and/or lymphovascular invasion (n=89) were compared. Metastasis was seen in six and seven patients in those groups, respectively. The difference in metastasis rate between the two groups was statistically significant (2.2 vs. 9.2%, P=0.008). CONCLUSION: RAI ablation is beneficial in the management of papillary thyroid microcarcinoma patients with histopathological risk factors. It also improves the sensitivity of thyroglobulin and antithyroglobulin, facilitating easier and safer follow-up.