Effect of light curing unit on resin-modified glass-ionomer cements: a microhardness assessment.
OBJECTIVE
To evaluate the microhardness of resin-modified glass-ionomer cements (RMGICs) photoactivated with a blue light-emitting diode (LED) curing light.


METHODS
Thirty specimens were distributed in 3 groups: Fuji II LC Improved/GC (RM1), Vitremer/3M ESPE (RM2) and Filtek Z250/3M ESPE (RM3). Two commercial light-curing units were used to polymerize the materials: LED/Ultrablue IS and a halogen light/XL3000 (QTH). After 24 h, Knoop microhardness test was performed. Data were submitted to three-way ANOVA and Tukey's test at a pre-set alpha of 0.05.


RESULTS
At the top surface, no statistically significant difference (p>0.05) in the microhardness was seen when the LED and QTH lights were used for all materials. At the bottom surface, microhardness mean value of RM2 was significantly higher when the QTH light was used (p<0.05). For RM1, statistically significant higher values (p<0.05) were seen when the LED light was used. No statistically significant difference (p>0.05) was seen at the bottom surface for RM3, irrespective of the light used. Top-to-bottom surface comparison showed no statistically significant difference (p>0.05) for both RMGICs, regardless of the light used. For RM3, microhardness mean value at the top was significantly higher (p<0.05) than bottom microhardness when both curing units were used.


CONCLUSIONS
The microhardness values seen when a LED light was used varied depending on the restorative material tested.
Cefaly
Daniela Francisca Gigo
DF
Department of Operative Dentistry, University North of Paraná, Londrina, PR, Brazil. dcefaly@uol.com.br
de Mello
Liliam Lucia Carrara Paes
LL
Wang
Linda
L
Lauris
José Roberto Pereira
JR
D'Alpino
Paulo Henrique Perlatti
PH
D003188:Composite Resins / Q000528:radiation effects; D055117:Curing Lights, Dental; D005899:Glass Ionomer Cements / Q000737:chemistry / Q000528:radiation effects*; D006219:Halogens; D006244:Hardness; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D012117:Resins, Synthetic / Q000528:radiation effects; D012666:Semiconductors; D013499:Surface Properties
D003188:Composite Resins; C444701:Filtek Z250; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D006219:Halogens; D012117:Resins, Synthetic; C084550:Vitremer