J Dent Hyg Sci.  2023 Jun;23(2):123-131. 10.17135/jdhs.2023.23.2.123.

Comparison of Surface Microhardness of the Flowable Bulk-Fill Resin and the Packable Bulk-Fill Resin according to Light Curing Time and Distance

• Kim HM
• Jeong MJ
• Lim HJ
• Lim DS

• KMID: 2544466
• DOI: http://doi.org/10.17135/jdhs.2023.23.2.123

Abstract

Background
As a restorative material used to treat dental caries, the light-curing type resin is widely used, but it has the disadvantage of polymerization shrinkage. The Bulk-Fill composite resin was developed to solve these shortcomings, but the existing research mainly focused on comparing the physical properties of a composite resin and a Bulk-Fill resin. A study on the light curing time and distance of the Bulk-Fill resin itself tend to be lacking.
Methods
This study compares the surface microhardness of specimens prepared by varying the light curing time and distance of smart dentin replacement (SDR) as a flowable Bulk-Fill resin and Tetric N-ceram as a packable Bulk-Fill resin, and confirms the polymerization time and distance that becomes the optimum hardness. To determine the hardness of the specimen, it was measured using the Vickers Hardness Number (Matsuzawa MMT-X, Japan).
Results
In SDR, the surface microhardness decreased as the distance increased in all time groups in the change distance from the curing tip. In the change of light curing time with respect to the distance from curing tip, the surface microhardness increased as the time increased. In Tetric N-ceram, the surface microharness showed no significant difference in the change of the distance of curing tip in the group of 20 and 60 second. But in the group of 10 and 40 seconds, decreased as the distance increased. The surface microharness increased as the light curing time increased in all distance groups.
Conclusion
When using SDR and Tetric N-ceram in clinical practice, it is considered that as the distance from the polymerization reactor tip increases, a longer light curing time than the polymerization time recommended by the manufacturer is required.

Keyword

Flowable bulk-fill resin; Light curing distance; Light curing time; Packable bulk-fill resin; Surface microhardness