PurposeSufficient area in the interforaminal region is required for dental implant placement, and the anterior loop of the mandibular canal is located within the limits of this area. The aim of this study was to evaluate the prevalence and extent of the anterior loop in a Brazilian sample population using cone-beam computed tomography (CBCT).Materials and MethodsCBCT images from 250 patients (500 hemimandibles) obtained for various clinical indications were randomly selected and evaluated to determine the presence and length of the anterior loop. The length of the anterior loop was then compared based on gender, age, and the side of the mandible. The data were analyzed using the Pearson chi-square test and linear regression analysis.ResultsAn anterior loop was identified in 41.6% of the cases, and its length ranged from 0.25 mm to 4.00 mm (mean, 1.1±0.8 mm). The loop had a greater mean length and was significantly more prevalent in males (p=0.014). No significant differences were found between the right and left sides regarding length (p=0.696) or prevalence (p=0.650).ConclusionIn this study, a high prevalence of the anterior loop of the mandibular canal was found, and although its length varied greatly, in most cases it was less than 1 mm long. Although this is a prevalent anatomical variation, safety limits for the placement of implants in this region cannot be established before an accurate evaluation using imaging techniques in order to identify and preserve the neurovascular bundles.

This study aimed to estimate the absorbed dose in cone beam computed tomography (CBCT) exams according to different exposure parameters and size and position of the field of view (FOV). In addition was compared the absorbed dose of two smaller FOV scans with that of a larger FOV scan for evaluation of temporomandibular joint (TMJ), as it is a bilateral structure. CBCT scans were obtained on OP300 Maxio unit varying scanning mode (standard, high and endo) as well as size (5x5, 6x8 and 8x15 cm) and positioning of FOV. With a small FOV, different areas were scanned (maxilla or mandible, anterior or posterior and TMJ). Absorbed doses were determined using thermoluminescent dosimeters on the skin surface of sensitive organs of an anthropomorphic phantom. Endo mode showed the highest dose, followed by the high and standard modes in all FOV positions. With small FOV, doses were higher in the posterior region, especially in the mandible. Dose reduction occurred when small FOVs were used, but it was not proportional to FOV size reduction. For TMJ, the dose in a single acquisition with large FOV was greater than two acquisitions with small FOV, but lower than two acquisitions with medium FOV (6x8 cm). In conclusion, scanning mode, size and FOV position have great influence on the absorbed dose. Small FOV decreases the dose, but there is no linear relation between FOV size and dose. For bilateral exams of TMJ, double acquisition with small FOVs produces decrease in absorbed dose relative to a large FOV.

Aim: Cone beam computed tomography (CBCT) was used to evaluate the ability of three NiTi rotary systems to maintain the original root canal anatomy. Methods: Sixty mesiobuccal canals of human mandibular first molars were divided into three groups with 20 root canals each. All teeth were scanned by CBCT before instrumentation. The images were captured digitally for further analysis using the Image Tools Software. The images were sectioned in three points, located at 9 mm, 6 mm and 3mm from the apex. In Group 1, the root canals were instrumented with ProTaper Universal™ rotary system; in Group 2, with Twisted File™ rotary system; and in Group 3, with M two ™ rotary system. Instrumented teeth were scanned again using CBCT and the images of the uninstrumented canals were compared with images of the instrumented canals. The results were statistically analyzed using the one-way ANOVA test. A level of significance of 0.05 was adopted.

Dens invaginatus is a rare developmental anomaly and its etiology remains controversial. Radicular dens invaginatus is an unusual dental anomaly. The aims of this paper are to report the radiographic and tomographic findings of a case of radicular dens invaginatus and to discuss the relevant features associated with this dental anomaly. A 16-year-old female was referred to a private oral radiology clinic for orthodontic evaluation. Radiographically, a morphological alteration to the root portion of the right mandibular first premolar and the presence of a discrete radiolucent periapical lesion were observed. The diagnosis was only elucidated after cone-beam computed tomography (CBCT). The CBCT images revealed enlargement of the root, and a dilated invagination with limited enamel that had its open site along the lateral portion of the root without evidence of buccal and lingual expansion. The diagnosis of radicular dens invaginatus was then established.

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