Comparing the Effect of Light Tip Distance Curing Units LED & Halogen on Z250 Composite Microhardness

Sadaghiani, Morad and Saghafi, Farnaz and BasirShabestari, Samira (2008) Comparing the Effect of Light Tip Distance Curing Units LED & Halogen on Z250 Composite Microhardness. Journal of Mashhad Dental School, 32 (2). pp. 137-142.

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Abstract

Introduction: Use of light-Curing units is an inseparable part of dentistry. They are used for curing conventional composites, glass inomers, and liners and for bonding orthodontic brackets. It is then necessary to evaluate recently developed light curing units (LED) and compare them to conventional halogen units at different distances. This study aimed to compare the effect of LED and Halogen light curing units at different distances on composite (Z250) microhardness. Materials & Methods: Microhybrid composite (Z250) with a Bis-GMA base (3M, ESPE) was used in this in vitro study. Plexiglass molds were provided with 10×10cm size and 2mm height and filled with composite Z250. Samples were then devided into four groups of ten each. Samples in the first group were cured using Halogen light curing unit (Astralis 7) at 0mm. Second group were cured using Astralis 7 at 5mm. Third group were cured using Apoza light Curing unit at "0mm" and the fourth group were cured using Apoza light curing unit at "5mm". After 20 second curing, samples were held in room temperature for 24 hours. Then microhardness test (Vickers, model 6100) was performed, over three seperate points with distance of 1mm with each other on superior and inferior surfaces of each samples. The analysis was done with ANOVA. Results: Statistical analysis revealed that microhardness on superior surface of Astralis 7 group at both “0mm and 5mm” was significantly higher than Apoza group. It was also revealed that microhardness in both units at “0mm” was significantly higher than “5mm”. BTR (bottom / top Ratio) at LED (Apoza) was significantly higher than Halogen (Astralis 7). Conclusion: Microhardness of all samples at a distance of “0mm” was significantly higher than samples curing at a distance of “5mm”. Microhardness of Z250 on superior surface after curing with Astralis 7 (Halogen) was significantly higher than samples curing with Apoza (LED) light curing unit. BTR at LED was significantly higher than Halogen. Key words: Microhardness, Halogen, LED light-curing unit, Z250 composite, distance.

Item Type: Article
Subjects: WU Dentistry. Oral surgery
Divisions: Journals > Journal of Mashhad Dental School
Depositing User: jmds jmds
Date Deposited: 24 Sep 2017 12:48
Last Modified: 24 Sep 2017 12:48
URI: http://eprints.mums.ac.ir/id/eprint/3104

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