Light intensity effects on resin-composite degree of conversion and shrinkage strain

Silikas, Nick; Εliades, George; Watts, D.C.

doi:10.1016/s0109-5641(00)00020-8

Cited by 398 publications

(308 citation statements)

References 11 publications

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“…This is probably a result of the fact that light-cured resin composites polymerize at a faster rate than chemical-cured resin composites. Although polymerization rate reduction may be achieved by decreasing light intensity [79][80][81][82], low light intensity decreases the degree of conversion that is associated with the mechanical properties of the resin composites, and this may result in poor clinical performance of the restorations [83]. Most of the stress reduction is believed to occur during the first 10 s of light activation [78].…”

Section: The Effect Of Light Curing Modesmentioning

confidence: 99%

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations

Kubo

Yokota

et al. 2013

Dental Materials

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Objectives: The incidence of non-carious cervical lesions (NCCLs) has been increasing.The clinical performance of resin composites in NCCLS was previously unsatisfactory due to their non-retentive forms and margins lying on dentin. In order to address this problem, a lot of effort has been put into developing new dentin adhesives and restorative techniques. This article discusses these challenges and the criteria used for evaluating clinical performance as they relate to clinical studies, especially long-term clinical trials. Polymerization contraction, thermal changes and occlusal forces generate debonding stresses at adhesive interfaces.Methods: In laboratory studies, we have investigated how these stresses can be relieved by various restorative techniques and how bond strength and durability can be enhanced. Lesion forms, restorative techniques, adhesives (adhesive strategies, bond strengths, bond durability, and the relationship between enamel and dentin bond strengths) were found to have a complex relationship with microleakage. With regard to some restorative techniques, only several short-term clinical studies were available.

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Section: The Effect Of Light Curing Modesmentioning

confidence: 99%

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations

Kubo

Yokota

et al. 2013

Dental Materials

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“…[1][2][3] Moreover the type of LCU and curing mode are known to impact on the polymerisation kinetics and associated stresses, micro-hardness, depth of cure [4][5][6] and the degree of conversion of RBCs. 7 Monomer conversion to polymer is an important determinant of the physico-mechanical properties of the resultant polymer 8 and RBCs that receive inadequate amounts of energy from a LCU, or energy…”

Section: Introductionmentioning

confidence: 99%

General dental practitioners' knowledge of polymerisation of resin-based composite restorations and light curing unit technology

Santini

Turner

2011

Br Dent J

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“…The literature also showed that in general the higher the monomer content and the more flowable, the higher the shrinkage [12,25,[31][32][33][34][35] and the faster the conversion rate to the gel phase [18,20,22]. Again, without the necessary information ( Table 1) this could not be meaningfully discussed.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, by increasing the filler content the resulting contraction stress that developed was found to be directly proportional to the filler content regardless of the matrix [20,28]. Therefore, the purpose of this study was to determine the relative volumetric change and the speed of shrinkage of bulk fill flowable composites relative to the composite Z250.…”

Section: Introductionmentioning

confidence: 99%

“…Some of these techniques resulted in a low initial conversion rate of the organic matrix. However, the moment the resin material became rigid, the internal stresses and polymerization stress started to increase [8,20]. It has been established that exposures not higher than 500 mW/cm², were able to provide a sufficient combination of irradiance and exposure time [15,21].…”

Section: Introductionmentioning

confidence: 99%

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Volumetric change of flowable composite resins due to polymerization as measured with an electronic mercury dilatometer

Mulder¹,

Grobler²,

Osman³

2013

Oral Biol Dent

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Background: To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. Materials and methods: A specially designed electronic mercury dilatometer was used to determine the volumetric change. The light intensity was 500mW/cm 2 . The mercury dilatometer measured the volumetric change every 0.5 seconds during the 35 second irradiation exposure time. The materials tested were Z250 as standard and control. Four bulk fill flowable composites were tested. Results: The sequence of total volumetric change was found to be: Z250 < Filtek bulk fill < Xtra-Base bulk fill < SDR < Venus bulk fill. The speed of shrinkage of the bulk fill flowables was faster than that of Z250, while the 2 flowables with the highest shrinkage speed (SDR and Venus) also had the highest total volumetric change. Of the different materials tested the volumetric change of Z250 (1.13%) was the lowest and significantly less (p<0.05) than that of SDR (1.55%) and Venus (1.72%). The material with the highest filler content (Z250) also showed the lowest shrinkage (1.13%) but this effect could not be seen in the flowables. In general, it was found that a 35 second irradiation period (with a light intensity of 500mW/cm 2 ) was satisfactory for complete polymerization of the resins. Conclusions:The volumetric changes and speed of shrinkage were higher for all 4 bulk fill flowable composites than for Z250. SDR and Venus flowables had the fastest and highest volumetric shrinkage. Clinical significance: The manufacturers of bulk fill flowable composites advocate filling layers of 4mm. However, because of the high shrinkage values found in this study it should be suggested that the standard 2mm layer increments still be used.

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Light intensity effects on resin-composite degree of conversion and shrinkage strain

Cited by 398 publications

References 11 publications

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations

General dental practitioners' knowledge of polymerisation of resin-based composite restorations and light curing unit technology

Volumetric change of flowable composite resins due to polymerization as measured with an electronic mercury dilatometer

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