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Showing 3 results for Delay
Effects of different curing methods and microleakage and degree of conversion of composite resin restorations
M. Hassani Tabatabaei , M. Ataei , H. Safar Charati ,
Volume 16, Issue 2 (5-2003)
Abstract

Statement of Problem: Recently, investigators have presented new methods to reduce polymerization shrinkage of composite resin restorations. It is claimed that more powerful light cure systems associated with a change in radiation patterns, lead to improved mechanical properties and reduced microleakage.

Purpose: The aim of the present study was to evaluate the effects of two curing systems, known as Soft-Start, Pulse-Delay, on microleakage and degree of conversion of composite resin restorations.

Materials and Methods: To evaluate microleakage, dye penetration method in class V cavities was applied. 30 extracted human molars filled with three different curing techniques, namely conventional, Soft-Start and Pulse-Delay, were compared. Degree of conversion was measured by FTIR Spectroscopy method immediately after sample curing. Kruskal- Wallis and Mann-Whitney test were used to compare groups.
Results: The degree of microleakage in enamel and dentin among three groups was not significantly different, however, microleakage in gingival and occlusal walls showed a significant difference among Pulse-Delay curing (P=0.001) and Soft-Start curing (P=0.28) groups, meaning that leakage gingival in wall was significantly higher than occlusal wall. This difference was not significant in conventional group. Moreover, the degree of conversion was not statistically significant among three groups (P-0.909).
Conclusion: Soft-Start and Pulse-Delay curing systems, with a two intensity start curing light, do not provide better marginal adaptation in class V composite resin restorations. It should be mentioned that polymerization degree is not also reduced in these methods.


Effect of delayed light curing methods on push-out bond strength of glass fiber posts in different root canal regions
Ali Eskandarizadeh, Shahram Farzin Ebrahimi, Niloofar Shadman, Saeed Rahmani,
Volume 30, Issue 2 (8-2017)
Abstract

Background and Aims: Delay in light irradiance can improve the polymeric structure and mechanical properties of resin cement and uniform stress distribution. The aim of this study was to evaluate the effect of light activation modes (immediate, 5 and 10-minute delay) on the push-out bond strength of cemented fiber posts with two types of resin cements in different of root canal regions.
Materials and Methods: In sixty extractedsingle canal and endodontic therapied roots, FRC Postec Plus were cemented with two resin cements, Nexus3 and Panavia F2.0, in three curing methods, immediate, 5, and 10 minute delay. After 24 hours storing in a dark place, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using the universal testing machine. Failure modes were evaluated using stereomicroscope. Data were analyzed by ANOVA and Tukey post hoc test with P<0.05 as the level of significance.
Results: In Nexus3, the immediate light curing had significantly higher bond strength (11.18±4.32) than delay methods (P=0.001). In Panavia F2.0, the 5-minute delay had significantly the highest bond strength (13.34±4.62) (P<0.05). There was no correlation between the different light curing methods and root canal regions. In Nexus3, the coronal region had higher bond strength (11.83±3.7) than that of middle (9.12±3.1) (P=0.015), and middle than of apical (5.65±2.77) (P=0.00), and coronal than that of apical (P=0.002). In Panavia F2.0, there were not significant differences among regions (P>0.05).
Conclusion: Delay in light curing of dual-cure resin cement's had different effects on the push-out bond strength.
 

Evaluation of survival rate in patients with laryngeal cancer
Ahmad Jafari, Narges Gholizadeh, Rashid Ramezani, Hanie Emami Razavi, Shamsolmoulouk Najafi,
Volume 30, Issue 2 (8-2017)
Abstract

Background and Aims: Cancer is the second most common cause of death in developed countries. The goal of this study was to determine the important epidemiologic factors affecting diagnosis and survival rate of patients with laryngeal SCC, for prevention, control and increase longevity.
Materials and Methods: In this study, all the cases recorded at the Center of Cancer Office of the Iran Ministry of Health in Tehran between 2005-2009 were examined. From 513 cases, 279 that their follow-up was possible by phone or postal address were included in the study. Data collection were performed from questionnaire. The data were analyzed by SPSS version 20. The Kaplan Meier survival curves were utilized and, moreover, the corresponding influential factors were examined by using the Cox regression test.
Results: The mean age of patients were 61.1 years (SD=10.54). The gender of 92.1% of patients were male. The most widely used method for the treatment was a combination of three methods of surgery, radiation therapy, and chemotherapy. The overall five-year survival rate was 75.7% (SD=0.03). The gender, histological differentiation, and professional delay did not exhibit a statistical correlation with the survival rate (P=0.38, 0.14, 0.52), whereas the age and patient delay had a statistically significant relation with the survival rate (P=0.03, 0.07).
Conclusion: The survival rate was lower in older patients. Patient and professional delays were high, which need more attention for improving the quality of life.
 

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