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Curing depths of a universal hybrid and a flowable resin composite cured with quartz tungsten halogen and light-emitting diode units.
Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
2004 (English)In: Acta Odontologica Scandinavica, ISSN 0001-6357, Vol. 62, no 2, 97-101 p.Article in journal (Refereed) Published
Abstract [en]

This in vitro study evaluated curing depths of a universal hybrid resin composite with two viscosities (Tetric Ceram and Tetric Flow) after curing with 6 different quartz tungsten halogen and light-emitting diode curing units. Irradiance (light intensity) of the curing units varied between 200 and 700 mW/cm2. The curing units were used for standard, soft-start, or pulse curing. Curing times were 20 and 40 s for standard curing, 3 + 10 s and 3 + 30 s for pulse curing, and 40 s for soft-start. Resin composite specimens, 5 in each group, with a diameter of 4 mm and a height of 6 mm, were made in brass molds and cured from one side at a distance of 6 mm. After 2 weeks, the specimens were ground longitudinally half through the specimen. Curing depth was then determined by measurement of Wallace hardness for each half millimeter starting at 0.5 mm from the top surface. For all curing units and for both resin composites an increased curing time led to statistically significantly higher depth of cure (P < 0.0005). Tetric Flow showed a statistically significantly higher depth of cure than Tetric Ceram (P < 0.0005). All curing units cured more than 2.0 mm of both composites from a distance of 6 mm at 20 s curing time. The value for 40 s was 3.0 mm. The composite closer to the surface than the depth of cure value was equally well cured with all curing units investigated. There was a significant linear correlation between the determined irradiance of the curing units and the depths of cure obtained (20s: r = 0.89, P < 0.025; 40 s: r = 0.91, P < 0.01).

Place, publisher, year, edition, pages
2004. Vol. 62, no 2, 97-101 p.
URN: urn:nbn:se:umu:diva-17144DOI: 10.1080/00016350410006905PubMedID: 15198390OAI: diva2:156817
Available from: 2007-11-02 Created: 2007-11-02 Last updated: 2009-11-19Bibliographically approved
In thesis
1. Resin composites: Sandwich restorations and curing techniques
Open this publication in new window or tab >>Resin composites: Sandwich restorations and curing techniques
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since the mid-1990s resin composite has been used for Class II restorations in stress-bearing areas as an alternative to amalgam. Reasons for this were the patients’ fear of mercury in dental amalgam and a growing demand for aesthetic restorations. During the last decades, the use of new resin composites with more optimized filler loading have resulted in reduced clinical wear. Improved and simplified amphiphilic bonding systems have been introduced. However, one of the main problems with resin composites, its polymerization shrinkage, has not been solved yet. During the polymerization of the resin composites, they shrink as a result of the conversion of the monomers into rigid polymers by a radical addition reaction. The resulting shrinkage stresses in the bonded resin composite restorations may cause adhesive failures at the resin composite/tooth structure interface and/or cohesive failures within the tooth or the resin composite. The interfacial failures may result in post-operative sensitivity, recurrent caries or pulpal injury. This thesis evaluates different restorative and light-curing techniques that are proposed to reduce the polymerization shrinkage and also the effect of new lightcuring units, light-emitting diodes (LED) and high-power quartz tungsten halogen (QTH) light on curing depth and degree of conversion of resin composites. Two restorative techniques using a polyacid-modified resin composite or a flowable resin composite in combination with conventional resin composite in sandwich restorations were evaluated in an intraindividual comparison with a conventional resin composite restoration. The durability of the polyacid-modified resin composite sandwich technique was investigated in a three year clinical follow-up study. A scanning electron microscope replica method was used for evaluation of the interfacial adaptation in vivo of both sandwich combinations. The depth of cure of the flowable resin composite was evaluated with the use of Wallace hardness testing. Degree of conversion for resin composite cured with the new LED units was evaluated with Fourier Transform Raman spectroscopy.

Major results and conclusions from the studies are:

• Neither the sandwich restoration with polyacid-modified resin composite nor the flowable resin composite improved the interfacial adaptation of the restorations.

• No difference in durability was found between the sandwich restorations with polyacidmodified resin composite or the resin composite restorations. A low failure rate was observed for both types of restorations after a clinical observation time of three years.

• The depth of cure of the flowable resin composite was higher than the depth of cure of the resin composite. It was found that the curing time of the resin composite studied could be reduced or the increment layer thickness increased compared to earlier recommendations.

• LED curing units of the latest generation were able to cure resin composites to a higher degree of conversion than the control QTH unit

• The use of soft-start curing did not improve the interfacial adaptation of neither of resin composite restorations tested.

Place, publisher, year, edition, pages
Umeå: Odontologi, 2005. 65 p.
Umeå University odontological dissertations, ISSN 0345-7532 ; 90
Medicine, Adaption, Clinical, Degree of conversion, Depth of cure, Flowable, Resin composite, Restorations, SEM, Medicin
National Category
urn:nbn:se:umu:diva-510 (URN)91-7305-833-5 (ISBN)
Public defence
2005-05-27, 09:00 (English)
Available from: 2005-04-22 Created: 2005-04-22 Last updated: 2016-06-02Bibliographically approved

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