Send to

Choose Destination
Dent Mater. 2008 Feb;24(2):199-203. Epub 2007 Jun 4.

Cross-link density evaluation through softening tests: effect of ethanol concentration.

Author information

Dental Materials Area, University of Campinas, School of Dentistry, Piracicaba, Brazil.



The aim of this study was to investigate whether the ethanol concentration used would influence the outcomes obtained through softening tests when comparing light-activation modes.


Disc specimens (n=20) of Filtek Z250 and Filtek Z100 (3M ESPE) were light activated by standard (S) and pulse-delay (PD) modes. Initial Knoop hardness (KHN) measurements were performed 24h after dry storage at 37 degrees C. Half of the specimens (n=10) of each resin-composite were stored in absolute ethanol (100%) and the other half in 75% ethanol solution, for 24h at room temperature, and KHN was determined anew. Initial hardness data were submitted to Student's t-test (p=0.05). Percentages of hardness decrease were analyzed by two-way ANOVA followed by pairwise Tukey's test (p=0.05). The statistical analyses were performed separately for each resin-composite.


No statistically significant differences were observed between standard and pulse-delay modes for initial Knoop hardness values. After storage in 75% ethanol solution, KHN was decreased in all cases but no significant differences were detected between light-activation modes (Filtek Z250: PD=12.6%, S=13.5%; Filtek Z100: PD=13.5%, S=11.8%) regardless of the resin-composite tested. After absolute ethanol storage, higher decrease in KHN were observed. Samples light-activated by the PD mode (Filtek Z250=20.4% and Filtek Z100=16.9%) exhibited significantly higher percentage decrease of KHN than specimens light-activated by the standard mode (Filtek Z250=14.1% and Filtek Z100=8.8%), regardless of the resin-composite tested.


The ethanol concentration affected the outcomes of the softening test.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center