Change search
ReferencesLink to record
Permanent link

Direct link
A Fourier transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units.
Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
2005 (English)In: Swedish Dental Journal, ISSN 0347-9994, Vol. 29, no 3, 105-112 p.Article in journal (Refereed) Published
Abstract [en]

The degree of conversion (DC), of a universal hybrid resin composite cured with LED curing units with low and high power densities and a 510 mW/cm2 quartz tungsten halogen unit, was investigated with Fourier Transform Raman spectroscopy. Three curing depths (0, 2, 4mm) and 0 and 7 mm light guide tip - resin composite (LT - RC) distances were tested. The DC of the LED units varied between 52.3% - 59.8% at the top surface and 46.4% - 57.0% at 4 mm depth. The DC of specimen cured with a 0 mm LT- RC distance at 4 mm depth varied between 50.8% - 57.0% and with 7 mm distance between 46.4% - 55.4%. The low power density LED unit showed a significantly lower DC for both distances at all depth levels compared to the other curing units (p < 0.05). Significant differences between the other curing units were only found at the 4 mm depth level cured from 7 mm distance (p < 0.05). The reduction in DC by increasing LT- RC distance was less than 10% for all curing units. It can be concluded that the improved LED curing units could cure the studied resin composite to the same DC as the control unit.

Place, publisher, year, edition, pages
2005. Vol. 29, no 3, 105-112 p.
URN: urn:nbn:se:umu:diva-17178PubMedID: 16255354OAI: diva2:156851
Available from: 2007-11-06 Created: 2007-11-06 Last updated: 2009-10-05Bibliographically 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

Open Access in DiVA

No full text


Search in DiVA

By author/editor
van Dijken, Jan
By organisation
Dental Hygiene
In the same journal
Swedish Dental Journal

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 94 hits
ReferencesLink to record
Permanent link

Direct link