Search results for "Root"
showing 10 items of 1237 documents
Single imputation method of missing values in environmental pollution data sets
2006
Abstract Missing data represent a general problem in many scientific fields above all in environmental research. Several methods have been proposed in literature for handling missing data and the choice of an appropriate method depends, among others, on the missing data pattern and on the missing-data mechanism. One approach to the problem is to impute them to yield a complete data set. The goal of this paper is to propose a new single imputation method and to compare its performance to other single and multiple imputation methods known in literature. Considering a data set of PM 10 concentration measured every 2 h by eight monitoring stations distributed over the metropolitan area of Paler…
Daytime sensible heat flux estimation over heterogeneous surfaces using multitemporal land-surface temperature observations
2016
Equations based on surface renewal (SR) analysis to estimate the sensible heat flux (H) require as input the mean ramp amplitude and period observed in the ramp-like pattern of the air temperature measured at high frequency. A SR-based method to estimate sensible heat flux (HSR-LST) requiring only low-frequency measurements of the air temperature, horizontal mean wind speed, and land-surface temperature as input was derived and tested under unstable conditions over a heterogeneous canopy (olive grove). HSR-LST assumes that the mean ramp amplitude can be inferred from the difference between land-surface temperature and mean air temperature through a linear relationship and that the ramp freq…
Diagnosis and treatment of dens invaginatus with open apex in a young adult patient by using cone-beam computed tomography and operative microscope.
2021
BACKGROUND: Dens invaginatus is a developmental anomaly that can affect both deciduous and permanent dentition. The anomaly is caused by the invagination of the enamel organ into the dental papilla prior to the calcification of the dental tissues. The treatment option changes according to the classification, from the simple filling of the invaginated enamel area to root canal treatment with or without retrograde surgery, intentional re-implantation, or the extraction of the affected tooth. CASE REPORT: In this study we report a case of a maxillary lateral incisor invaginatus in a young adult patient. The periapical endoral X-ray showed the presence of a periapical radiolucency in tooth 22, …
Cutting efficiency of heat-treated nickel-titanium single-file systems at different incidence angles.
2020
Cutting efficiency of Reciproc R25 (REC) and Reciproc blue R25 (REB) at different inclinations was evaluated. Sixty new files were tested at 90°, 70° and 45° of inclination in relation to the sample (n = 10), using a customised machine. All files were activated in reciprocation against standardised gypsum blocks for 120 s. Cutting efficiency was determined by measuring the block weight loss with an analytical balance and measuring the length of the block surface cut using a digital calliper. Data were statistically analysed (two-way ANOVA, Bonferroni t-test) with the significance level set at P < 0.05. There was no difference for REC among the tested angles. REB had no statistical differenc…
Length of endodontic files measured in digital radiographs with and without noise-suppression filters: an ex-vivo study
2011
The aim of this study is to evaluate if theoretically possible edge shifts induced by noise-suppression filters potentially occur on objects found in digital radiographs. Most manufacturers carry out noise-suppression filtering of their images before they are displayed to the user. It is not usually possible for the user to disrupt the function of the filters. The use of these filters can lead to deletion of small image structures.K-files (ISO size 06, 08, 10 and 15) were placed in the root canals of 6 human teeth located in cadaver jaw segments. File tip positions were measured on original and filtered digital images by three observers. The file position was marked on each filtered image a…
Electrochemical corrosion assessment of RaCe and Mtwo rotary nickle-titanium instruments after clinical use and sterilization
2010
Aim: The aim of the present study was to electrochemically evaluate corrosion resistance of RaCe and Mtwo files after repeated sterilization and preparation procedures. Study Design: A total of 450 rotary files were used. In the working groups, 72 files from each file type were distributed into 4 groups. RaCe and Mtwo files were used to prepare one root canal of the mesial root of extracted human mandibular first molars. The procedure was repeated to prepare 2 to 8 canals. The following irrigation solutions were used: group 1, RaCe files with 2.5% NaOCl; group 2, RaCe files with normal saline; group 3, Mtwo files with 2.5% NaOCl; and group 4, Mtwo files with normal saline in the manner desc…
A comparative study of the sealing ability of two root canal obturation techniques
1995
A comparison was made of the ability of two root canal obturating techniques to prevent dye microleakage: gutta-percha lateral condensation and mechanically plasticized gutta-percha (JS Quick-fill). Twenty central incisors were prepared and obturated by each technique. After rendering the teeth transparent, linear dye penetration was found to be 0.48 and 0.52 mm, respectively. The difference between the two techniques was not significant. As for the distribution of the sealing cement (AH26) in the teeth obturated with JS Quickfill, the cement was located in the most peripheral zone of the obturation alongside the dentinal walls, whereas the gutta-percha was found in the central part of the …
Root Canal Morphology and Configuration of 179 Maxillary First Molars by Means of Micro-computed Tomography: An Ex Vivo Study
2015
Introduction The objective of this study was to propose a root canal configuration description method and to investigate the root canal system morphology of the maxillary first molar by means of micro-computed tomographic imaging. Methods The root canal configuration, foramina, and accessory canal frequency of 179 maxillary first molars were investigated by means of micro-computed tomographic imaging and 3-dimensional software imaging. The root canal configuration and main foramina number are described from coronal to apical with a 4-digit system. Results The most frequent root canal configurations were 1-1-1/1 (45.8%), 2-2-2/2 (25.1%) and 2-2-1/1 (10.1%) in mesiobuccal roots and 1-1-1/1 in…
Shaping ability of nickel-titanium rotary instruments in simulated S-shaped root canals.
2009
Objective The aim of this study was to compare the shaping ability of 4 nickel-titanium rotary techniques and 1 hand technique in simulated S-shaped curved root canals. Study design Seventy-five simulated double-curved resin root canals were divided into 5 groups (n = 15). The canals were compared at 12 different levels and at 3 different times: before preparation and after preparation to master apical 25 and 35. Data were statistically analyzed by performing 2-by-2 comparisons with the Tukey parametric test of variance analysis using a confidence interval of 95%. Results All of the 75 resin blocks presented transportation of the root canals by transforming the apical curvature into a strai…
Influence of prefabricated post material on restored teeth: fracture strength and stress distribution.
2006
This work studied how prefabricated intraradicular post material affects the mechanical performance of restored teeth. The effect of using two different materials (glass fiber and stainless steel) with significantly different elastic moduli was studied.A combined theoretical and experimental method was used: first, an experimental fracture strength test was performed on 60 extracted human maxillary central incisors. The teeth were decoronated, treated endodontically and restored, 30 with glass fiber posts and 30 with stainless steel posts. The data were recorded and the results compared using an ANOVA test. Then, the finite element technique was used to develop a model of the restored tooth…