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Article
Effect of curing modes on the depth of cure of resin composite

Author: Abdul–Adheem R Al–Mallah
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 2 Pages: 195-200
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To study the effect of different curing modes of Light emitting diodes (LED) curing unit on thedepth of cure (DOC) of composite resin with light and dark shades and compare the results withconventional curing method by the use of halogen curing light. Materials and Methods: A total of 40cylindrical composite resin samples (4mm diameter and 6mm height) were prepared, 20 of light shadeand 20 of dark shade. They were subjected to four curing modes (n=5 for each group): conventionalhalogen light, and three modes related to the LED light curing unit (LCU) which were: Fast (F); Ramped(R); and Pulsed (P). The samples were irradiated to the time required by the manufacturer for each curingmode, and a digital micrometer was used to measure the depth of cure according to scraping methoddescribed in ISO 4049:2000. Data were collected and analyzed for comparison. Results: No significantdifference was found in the DOC of composite irradiated by LED curing light for all of the three curingmodes or shade. However, the LED produced significantly greater depths of cure when compared withconventional halogen curing unit for both shades. The lighter shade was cured to a significantly greaterdepth than dark one when considering halogen LCU. Conclusions: All curing modes of the LED lightcan produce similar DOC regardless of composite shade when irradiated to the time recommended by themanufacturer. However, Curing with conventional halogen curing unit yielded the least DOC values forlight or dark shades when compared with LED units. Longer irradiation times are needed to cure darkshades by the use of halogen LCUs.


Article
Fracture Resistance of Premolars with Different Filling Techniques

Author: Ammar Kh Al–Nori
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 3 Pages: S103-S108
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the fracture resistance of premolars with mesio–occluso–distal (MOD) preparations with resin composite using different incremental techniques when submitted to occlusal load. Materials and Methods: Fifty premolars were used and randomly divided into five groups of ten teeth each. The teeth in group I were prepared and not restored. The teeth in group II were restored in vertical technique. Teeth in group III were restored in horizontal technique. Teeth in group IV were restored in oblique technique. Teeth in groups II, III and IV were restored using Exite adhesive system and Tetric hybrid composite. Teeth in group V were restored in horizontal technique using combinations of Tetric flowable composite and Tetric hybrid composite. After thermocycling, the teeth were tested under universal compression machine. The data obtained in this research were subjected to analysis of variance and Duncan’s Multiple Range Test. Results: Both groups V and IV significantly increase the fracture resistance of teeth over groups II and III. Conclusions: Selection and appropriate use of materials, better placement technique and control polymerization shrinkage may increase the resistance of teeth to fracture with Class II resin composite restorations.

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