Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods

Obici, Andresa Carla; Sinhoreti, Mário Alexandre Coelho; Sobrinho, Lourenço Correr; Góes, Mário Fernando de; Consani, Símonídes

doi:10.1590/s0103-64402004000300007

Cited by 32 publications

(32 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…20 However, since the microhardness value is greatly influenced by factors, such as filler loading of the composite, cross-comparison between the different brands is limited. [4][5]21 There may be a difference in the sensitivity to detect small changes in monomer conversion of a composite between the two techniques. 22 Therefore, the current study employed both the FTIR spectroscopy and microhardness test to evaluate changes in monomer conversion within the same resin cement as a function of time.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Changes in Degree of Conversion and Microhardness of Dental Resin Cements

Yan

Kim²,

Kim³

et al. 2010

Operative Dentistry

View full text Add to dashboard Cite

Resin specimens were prepared for Fourier transform infrared (FTIR) spectroscopy and microhardness testing to determine the DC and Vickers hardness (VH), respectively. The lightcured materials or mixed pastes of the dualcured materials were irradiated with a light-curing unit (Elipar TriLight) through a precured composite overlay for 40 seconds. The FTIR spectra and microhardness readings were taken at specified times: 1, 2, 5, 10, 15, 30 and 60 minutes; 24 hours and after two days and seven days. YL Yan • YK Kim K-H Kim • T-Y Kwon Clinical RelevanceChemical-and dual-cured resin cements, as well as light-cured resin cements, appear to be cured within the first 24 hours post-mix or post-light activation with no further significant changes in the degree of conversion or microhardness.According to the FTIR study, most of the curing reaction of Choice 2 and RelyX Veneer occurred within 10 and 30 minutes, respectively. Multilink, C&B Cement and Calibra exhibited gradual increases in the DC up to 24 hours, with no further statistically significant increase (p>0.05). RelyX ARC attained a DC value within five minutes, similar to that at seven days (p>0.05). Choice 2 and RelyX ARC showed gradual increases in the VH, up to 15 minutes, with no further significant change over the remaining observation time (p>0.05). For RelyX Veneer, Multilink, C&B Cement and Calibra, there were no significant increases in the VH value after 24 hours (p>0.05). The light-cured materials produced significantly higher DC values than the chemicalcured materials (p<0.05). The DC values of the two dual-cured resin cements were significantly different from each other (p<0.001). The results suggest that the significant polymerization reaction was finished within 24 hours post-mix or post-light activation for all resin cements tested.

show abstract

Section: Discussionmentioning

confidence: 99%

“…2,[4][5]21 Although microhardness is one of the mechanical properties, it does not reflect the behavior of the bulk material. 29 The clinical success of resin cements will depend on many other properties, such as handling properties, bonding strength with tooth and restoration, color stability and wear resistance.…”

Section: Discussionmentioning

confidence: 99%

Changes in Degree of Conversion and Microhardness of Dental Resin Cements

Yan

Kim²,

Kim³

et al. 2010

Operative Dentistry

View full text Add to dashboard Cite

show abstract

“…These outcome might be attributed to the fact that, because of the short exposure time to PAC light, low energy density is delivered to the resin cement (13). This low energy leads to a low degree of conversion of the cement, determined indirectly by hardness measurements (14).…”

Section: Discussionmentioning

confidence: 99%

Effect of light-curing methods on resin cement knoop hardness at different depths

et al. 2007

Self Cite

View full text Add to dashboard Cite

This study evaluated, using Knoop hardness test, the polymerization depth of Rely-X dual-cured resin cement activated by chemical reaction alone (control group) or by chemical/physical mode with light curing through a 1.5-mm-thick ceramic layer (HeraCeram). Bovine incisors had their buccal surface flattened and hybridized. On this surface, a rubber mould (5 mm diameter; 1 mm high) was bulk filled with cement. Either a polyester strip or a 1.5-mm-thick disc of the veneering material was seated over this set. Light curing was performed with either conventional halogen light (QTH; XL2500) for 40 s, light-emitting diode (LED; Ultrablue Is) for 40 s or xenon plasma arc (PAC; Apollo 95E) for 3 s. In a control group, cement setting occurred by chemical reaction alone. After storage dry in dark (24 h/37 o C), the specimens (n=5) were sectioned for hardness (KHN) measurements at three depths in a microhardness tester (50 gf load/15 s). Data were submitted to ANOVA and Tukey's test (α = 0.05). Rely-X cement presented higher Knoop hardness values when the QTH and LED LCUs were used, compared to the control group and PAC. Light curing with PAC resulted in lower hardness compared to the control group. Cement hardness was significantly lower in deeper regions.

show abstract

“…A significant problem that arises when using low intensities is lower degree of conversion (DC) and a reduced curing depth 6,7 . Thus, longer curing times [7][8][9] or post curing at higher intensity [10][11][12] can compensate this problem. Several technologies have been suggested to initiate the polymerization reaction.…”

Section: Introductionmentioning

confidence: 99%

“…Some variations in technique may be performed in an attempt to reduce polymerization shrinkage, whilst maintaining the DC. Such variations include stepped light [10][11][12][13] , exponential light 14 and intermittent light 12 . Another method employs the plasma arc curing (PAC) lamps, which provide a high intensity in a short time 15 .…”

Section: Introductionmentioning

confidence: 99%

Degree of conversion of Z250 composite determined by fourier transform infrared spectroscopy: comparison of techniques, storage periods and photo-activation methods

Obici

Sinhoreti

Frollini³

et al. 2004

Mat. Res.

Self Cite

View full text Add to dashboard Cite

The purpose of this study was to evaluate the degree of conversion (DC) of the Z250 composite, using six photo-activation methods, two storage periods and two preparation techniques of the FTIR specimens (n = 3). For the KBr pellet technique, the composite was placed into a metallic mold and photo-activated as follows: continuous light, exponential light, intermittent light, stepped light, PAC and LED. The measurements were made after 24 h and 20 days. For the resin film technique, approximately 0.07 g of the composite was pressed between two polyester strips, photoactivated as above described and analyzed. The DC was calculated by the standard technique and submitted to ANOVA and Tukey's test (α = 5%). Independently of the storage period and specimen preparation technique, there were no significant differences among photo-activation methods. No statistical difference was observed between the time periods used. The specimens analyzed under the KBr pellet technique presented higher DC values than those analyzed by the resin film technique.

show abstract

Evaluation of depth of cure and Knoop hardness in a dental composite photo-activated using different methods

Cited by 32 publications

References 13 publications

Changes in Degree of Conversion and Microhardness of Dental Resin Cements

Changes in Degree of Conversion and Microhardness of Dental Resin Cements

Effect of light-curing methods on resin cement knoop hardness at different depths

Degree of conversion of Z250 composite determined by fourier transform infrared spectroscopy: comparison of techniques, storage periods and photo-activation methods

Contact Info

Product

Resources

About