Open AccessEvaluation of depth of cure and knoop hardness in a dental composite, photo-activated using different methods
Author(s) -
Mithra N Hegde,
Priyadarshini Hegde,
Babita Malhan
Publication year - 2008
Publication title -
journal of conservative dentistry/journal of conservative dentistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.533
H-Index - 31
eISSN - 0974-5203
pISSN - 0972-0707
DOI - 10.4103/0972-0707.44055
Subject(s) - knoop hardness test , materials science , indentation hardness , composite number , composite material , mathematics , microstructure
The study aimed at evaluating the depth of cure and knoop hardness of a microfine-hybrid composite resin that was photo-activated using different methods. A bipartite brass mold was filled with composite resin and photo-activation was performed using four methods: (1) Intermittent method using quartz tungsten halogen (QTH) light curing unit (LCU) (2) Continuous method (QTH) (3) Exponential method (QTH) (4) Continuous method using light-emitting diode (LED). Depth of cure was measured at the unexposed bottom surface of the specimen using microtester as a penetrometer. The surfaces exposed to light were subjected to knoop hardness testing, using a digital microhardness tester. Knoop hardness measurements were obtained at the top surface and at depths of 1, 2, 3, 4 and 5 mm. The data was analyzed using anova and Tukey's test (5%). Results showed that the depth of cure was higher with the intermittent method (QTH), followed by the continuous method (QTH), the exponential method and the continuous method (LED). At the top surface and up to 1 mm, continuous method (LED) demonstrated the highest knoop hardness number (KHN). At 2 mm and up to 5 mm, intermittent method (QTH) presented the highest KHN and continuous method (LED) showed the lowest KHN. At all depths, continuous method (QTH) showed higher KHN, as compared to the exponential method (QTH), except at 2 mm where both showed no significant difference.