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

Hegde MN, Hegde P, Malhan B - J Conserv Dent (2008)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore, Karnataka, India.

ABSTRACT
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.

No MeSH data available.


Bar Diagram representing the time and intensity of light used in continuous method (LED) of photo-activation
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Figure 0004: Bar Diagram representing the time and intensity of light used in continuous method (LED) of photo-activation

Mentions: For the continuous method using LED, BlueLex (Monitex Industrial Co. Ltd) LED LCU was used according to the manufacturer's information. When the battery was fully charged, photo-activation was performed for 30 seconds, with an intensity of 480 mW/cm2, using the continuous method of photo-activation [Figure 4]. Photo-activation was performed for 30 seconds; this was recommended by the manufacturer because low intensity LED used for 30 seconds is sufficient to cure the same depth of composite, as can be cured with QTH. The light intensity of both the curing units was measured with a radiometer (Curing Radiometer, Optilux 501) to ensure consistency in the output.


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

Hegde MN, Hegde P, Malhan B - J Conserv Dent (2008)

Bar Diagram representing the time and intensity of light used in continuous method (LED) of photo-activation
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2813097&req=5

Figure 0004: Bar Diagram representing the time and intensity of light used in continuous method (LED) of photo-activation
Mentions: For the continuous method using LED, BlueLex (Monitex Industrial Co. Ltd) LED LCU was used according to the manufacturer's information. When the battery was fully charged, photo-activation was performed for 30 seconds, with an intensity of 480 mW/cm2, using the continuous method of photo-activation [Figure 4]. Photo-activation was performed for 30 seconds; this was recommended by the manufacturer because low intensity LED used for 30 seconds is sufficient to cure the same depth of composite, as can be cured with QTH. The light intensity of both the curing units was measured with a radiometer (Curing Radiometer, Optilux 501) to ensure consistency in the output.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Conservative Dentistry and Endodontics, A. B. Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore, Karnataka, India.

ABSTRACT
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.

No MeSH data available.