Introduction: The purpose of this study was to find out the prevalence of C-shaped canals configurations in mandibular 2nd molar and to investigate the gender prevalence. Materials and Methods: A sample of 1200 patients’ cone beam computed tomography (CBCT) scans were screened and evaluated by a maxillofacial radiologist assessed the axial, sagittal, and coronal sections. Inclusion criteria applied to 801 patients (452 females and 349 male) aged 14–75 years were included in this study with total of 1567 mandibular 2nd molar was evaluated. Inclusion criteria: Available CBCT images of mandibular posterior teeth with at least one mandibular 2nd molar in the scan, absence of root canal treatment, absence of coronal or post coronal restorations, absence of root resorption or periapical lesions, and high-quality images. Canal configuration was classified by criteria’s which described by Fan et al. (2004): (i) Fused roots, (ii) a longitudinal groove on the buccal or lingual surface of the root, and (iii) at least one cross-section of the canal belongs to the C1, C2, or C3 configuration. Results: Considering 801 patients, 97 (12.1%) patients females 57 (7.1%) and 40 (5%) males had a C-shaped canal with no statistical difference between females and males (P > 0.05). Conclusion: The occurrence of C- shaped canal mandibular 2nd molar is approximately 12.1% and no significant difference was found by gender.

It is essential to know dental arch dimensions to provide accurate diagnosis and treatment planning to ensure the satisfactory outcome of orthodontic treatment. The aim of the present study was to measure and compare dental arch dimensions of a Kurdish sample in Erbil city with normal and different classes of malocclusion. Arch width and length were measured by an electronic digital caliper on a total of 150 orthodontic models of school students aged 16–20 years of different occlusal relationships (Class I normal occlusion, Class I, Class II division I, Class II Division II, and Class III malocclusions). The results showed that (1) girls have smaller arch parameters than boys; (2) Class II division II malocclusion showed a significantly smaller upper inter canine width, arch length, incisor molar distance, and incisor canine distance when compared to all other groups; (3) the upper inter premolar and inter molar width were significantly narrower in Class II division I malocclusion than of normal occlusions and Class III malocclusion and also narrower in Class I malocclusion than in normal occlusions for both arches; (4) the arch length was significantly longer in Class II division I when compared to Class II division II, Class I malocclusions (P < 0.01), Class III malocclusion and Class I normal occlusion (P < 0.05), and (5) no statistically significant differences were found in all the arch dimensions for Class III malocclusion when compared with the normal occlusion. In conclusion, girls had smaller arch dimension than boys and Class II Division II malocclusion showed smaller arch in all dimensions while Class II division I malocclusion revealed narrower arch width and longer arch length.

Backgrounds:The aims of this study were to; Evaluate the amount of in-vitro microleakage of three different types of pit and fissure sealants (Vertise Flow, Kerr), (Helioseal-F, IvoclarVivadent), (GC Fuji TRI-AGE, GC corporation) and the effect of occlusal preparation on the leakage value.Methods: Sixty extracted human premolars randomly divided into 6 groups (n=10/group). Teeth fissures of three non-invasive groups (1, 3, 5) left intact, fissures of other three invasive groups (2, 4, 6) were opened up with ¼ round bur. Teeth fissures in group (1, 2) sealed with self-adhesive Vertise Flow, group (3, 4) Helioseal-F, while group (5, 6) fissures sealed with Glass Ionomer GC Fuji TRIAGE. The teeththermocycled between 5±2°C and 55±2°C for 500 cycles with a dwell time of 30 seconds; All teeth sealed apically and coated within 1.5 mm of the sealant margin with two layers of nail varnish, then immersed in 1% Methylene blue solution. Subsequently, two buccolingual sections were made parallel to the long axis of tooth yielding 3 sections and 4 surfaces per tooth for microleakage analysis. The surfaces were scored 0 to 3 for extent of microleakage using a binocular microscope at 25X magnification. Microleakage was analyzed by using paired t-test and ANOVA. Results:Invasive technique produced significantly less microleakagethan Non-Invasive groups (P<0.05). In all six groups Helioseal-F in Invasive technique showed significantly the least degree of microleakage (P<0.05). Conclusion:Helioseal-F was the best material in terms of reducedmicroleakage. Invasive techniquecompared to non-invasive technique had produced less degree of microleakage.