Changes in Geometry and Transportation of Root Canals with Severe Curvature Prepared by Different Heat-treated Nickel-titanium Instruments: A Micro-computed Tomographic Study.

INTRODUCTION: The aim of this study was to compare the shaping ability of 4 different nickel-titanium systems, considering their variation in alloy treatment, kinematics, and design, used to prepare canals with severe curvature using micro-computed tomographic analysis. METHODS: Thirty-two mesial roots of mandibular molars with severe curvature were matched based on similar morphologic dimensions and assigned to 4 experimental groups (n = 8) according to the canal preparation: ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (RC; VDW GmbH, Munich, Germany), Reciproc Blue (RCB, VDW GmbH), and TRUShape (TRU; Dentsply Tulsa Dental Specialties, Tulsa, OK) systems. Changes in 2-dimensional (area and perimeter) and 3-dimensional (volume, surface area, and structure model index) morphologic parameters as well as canal transportation were compared among groups using the analysis of variance post hoc Tukey tests with the significance level set at 5%. RESULTS: Preparation significantly increased all analyzed parameters. No statistically significant differences (P > .05) were observed between RC and RCB or between PTN and TRS in any of the analyzed parameters. In the cervical third, RC and RCB presented higher mean increases than PTN and TRU. In the apical third, there were no statistically significant differences (P > .05) among the systems. CONCLUSIONS: The instruments of greater taper may promote greater morphologic changes. However, regardless of the number of instruments (multiple or single), the type of movement (rotation or reciprocating), the type of heat treatment of alloys, and the particular characteristics of each instrument (taper and design), the evaluated systems did not result in different dimensional changes and canal transportation in the critical apical area.

Demographic profile of oral nonodontogenic cysts in a Brazilian population.

OBJECTIVES: The purpose of this study was to determine the clinical and demographic characteristics of oral non-odontogenic cysts (ONOC) in a Brazilian population over a 53-year period and to compare this data with the literature. STUDY DESIGN: A total of 20.391 biopsies records were evaluated, from April/1959 to August/2012. Cases of oral developmental cysts were selected. Data regarding age, gender, time of evolution, and anatomic site of all cases were collected. The data were analyzed by descriptive statistics. RESULTS: Among 20.391 oral biopsies, 71 (0.35%) met the criteria of ONOC. Females accounted for 50.70% of all cases. The mean age observed was 38.14 years (range: 5-88 years). Nasopalatine duct cysts, oral lymphoepithelial cysts and epidermoid cysts were the most common ONOC, accounting for 63 cases (88.73%). Nasopalatine duct cysts occurred in 31 cases (43.66%), followed by 22 patients with oral lymphoepithelial cysts (30.99%) and 10 cases of epidermoid cysts (14.08%). Nasopalatine duct cysts revealed predominance among males (58.06). Oral lymphoepithelial cysts were more commonly observed in tongue (50%). Epidermoid cysts were most frequently found in the buccal mucosa (40.00%). CONCLUSIONS: The differential diagnosis of ONOC is based on the clinical, radiological, and histological findings. It is difficult to establish an epidemiological profile of ONOCs, considering the low frequency of these lesions and the divergences in the demographic and clinical presentation data among different populations.