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Showing 3 results for Measurement
Designing and evaluation of validity and reliability of a new device for measurement of axial wall tapering of prepared teeth for fixed crown prosthesis
Hamid Jalali, Farzaneh Farid, Abdolsalam Abobakry, Maryam Mohajerfar,
Volume 25, Issue 2 (4-2012)
Abstract

Background and Aims: The purpose of this study was to design a new device assisting dental students to measure the tapering of the prepared teeth for fixed crown prosthesis in which the desired tapering for better clinical prognosis could be obtained.

Materials and Methods: The designed device in this study had two arms that were placed on two opposite walls of the prepared teeth. To evaluate the validity and reliability of this device, 3 dies with different degrees (13, 29 and 45°) were used and 20 teeth were prepared by dental students with undefined tapering degrees. The measurements of tapering were performed by six last year-dental students in two different time periods. Comparison of errors in measurements on standard dies between observers and between time intervals were analyzed by (Wilcoxon) Paired t-test with a significance level of α=0.05.

Results: For the three dies used in this study, we compared the differences for each measurement taken by observers with the standard taper of the dies. Maximum difference of measurements with true standard die tapering was 1 degree. A number of 6 measurements were under the true standard tapers and 2 measurements were above it. Interclass Correlation Coefficients (ICC) of the first and second measurements on prepared teeth were 97.4 and 97.5, respectively.  There were no significant differences between different observers or two measurements of the same observer in different time intervals (P>0.05).

Conclusion: The results indicated that this device can be valid and reliable for measuring the angle of convergence of the prepared teeth and can be used as an educational device in dental schools as a replacement for previous tapering measurement methods.


Efficacy of calibration function by CMOS digital system software for working length estimation
Mohtavipour Seyedeh Tahereh , Seyedeh Saeideh Mohtavipour, Alieh Sadat Javadzadeh Haghighat, Shiva Sadeghi, Maryam Rezvani, Bahar Mahmoud Khalesi,
Volume 29, Issue 1 (7-2016)
Abstract

Background and Aims: Estimating the canal length is essential for reaching to a proper endodontic treatment. Any error and miscalculation in estimation of the working length, especially in curved canals, can result in complication during and after root canal therapy. The introduction of digital radiography has enabled us to measure curved canal length. The purpose of this study was to evaluate the calibration tool of Complementary Metal Oxide Semiconductor (CMOS) digital system in estimation of working length.

Materials and Methods: In this in-vitro study, 80 extracted molar teeth were selected and randomly divided into three groups based on angle and radius of canal curvature. A 5 mm orthodontic wire was placed on the lateral surface of the root. Conventional radiographs were taken after insertion of endodontic file in the apical third of root canals. Radiographic images were scanned and imported to the software of CMOS digital system. Two observers estimated the file lengths with and without using calibration tool of digital measurement software. The correlation between observers was evaluated and then data were analyzed using Paired T-test with 95% confidence.

Results: Overall agreement between observers was good. There was no significant difference between the mean values of calibrated measurement and true file length in the basis of canal curves (P>0.001). However, there was significant difference between the mean values of uncalibrated measurement and true file length in the basis of canal curvature (P<0.001).

Conclusion: The calibrated measurement of file length was more accurate than that of the uncalibrated file length measurement.


Comparing color coordinates of three ceramic systems with corresponding shade guide
Farzaneh Farid, Pedram Etemadi, Farhad Shafiee,
Volume 30, Issue 2 (8-2017)
Abstract

Background and Aims: Increase of esthetic demands among dental patients has led to development and wide spread use of tooth colored ceramic systems for fabricating fixed restorations. However, they do not have same capability of matching the target color. The aim of this study was to compare the color coordinates of three widely used systems with A2 tab from a Vita Lumin Classic shade guide.
Materials and Methods: In this study, three ceramic systems were tested. The metal-ceramic(MCR) with 0.5 mm core and 1 mm Ceramco lll veneering layer; the all ceramic (CE) with 0.5 mm Cercon core and 1 mm Cercon Ceram veneering layer, and the all porcelain (VM7) with 1.5 mm Vita VM7. For each system, 15 disks (1.5mm×10mm) were made in Vita A2 shade. L*a*b* coordinates of the samples were measured by spectrophotometer and the color difference with Vita A2 shade was calculated. The data were analyzed using one way ANOVA and multiple Tukey tests.
Results: The color coordinates of the target shade was L*=72.45, a=1.59 and b*=14.11. The mean L*a*b* values for MCR were 72.61±0.38, 2.88±0.24, 15.51±0.64, for CE were 76.42±0.46, 2.77±0.14, 17.51±0.61, and for VM7 were 75.13±0.6, 2.15±0.19, 17.9±0.61, respectively. The difference between coordinates of each system with target shade was significant. Only for MCR group, ΔE was in acceptable range (1.98). For CE (Δ=5.38) and VM7 (Δ=4.72) groups, the difference was unacceptable.
Conclusion: Under the condition of this study, the metal-ceramic system had the best and acceptable match to the target shade.
 

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