The Effect of Different Light-curing Units and Tip Distances on the Polymerization Efficiency of Bulk-fill Materials.

Autor:	Al Nahedh H; Hend N A Al Nahedh, BDS, MSD, College of Dentistry, Department of Restorative Dental Sciences, King Saud University, Riyadh, Saudi Arabia., Al-Senan DF; Dana F Al-Senan, BDS, MSD, College of Dentistry, Clinical Dental Sciences Department, Princess Nourah University, Riyadh, Saudi Arabia., Alayad AS; Abdullah S Alayad, BDS, CAGS, MSD, DScD, College of Dentistry, Department of Restorative Dental Sciences, King Saud University, Riyadh, Saudi Arabia.
Jazyk:	angličtina
Zdroj:	Operative dentistry [Oper Dent] 2022 Jul 01; Vol. 47 (4), pp. E197-E210.
DOI:	10.2341/20-282-L
Abstrakt:	Problem Statement: In an average class II posterior preparation, the curing light tip is placed at a distance from the restoration surface that far exceeds the 1-mm manufacturer's recommendation. This distance can have potentially detrimental effects on the curing efficiency of the light-curing unit as well as the properties of the resin-based composite restoration, especially at the bottom of the cavity preparation. Purpose: The purpose of this study was to evaluate the effects of various types of light-curing units (LCUs) and the different curing distances on the degree of conversion (DC) and the surface hardness of bulk-fill composite materials. Methods and Materials: A total of 390 specimens of three resin-based composites (RBCs) were fabricated. Two bulk-fill RBCs, including Filtek Bulk Fill Posterior (3M ESPE GmbH, Seefeld, Germany) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent AG, Schaan, Liechtenstein), as well as a Filtek Z350 XT nano-filled composite (3M ESPE GmbH, Seefeld, Germany), were utilized. In this study, the Vickers microhardness number (VMN) and the DC were evaluated at 2 and 4 mm thicknesses. Polymerization for 20 seconds was performed using two high-power light-curing units, namely the polywave Bluephase G2 light-emitting diode (LED) LCU (Ivoclar Vivadent AG, Schaan, Liechtenstein) and the monowave Elipar Deep Cure S LED LCU (3M Oral Care, St Paul, MN, USA) at 0, 2, and 4 mm distance between the curing tip and the RBC surface. The results were analyzed using the two-way analysis of variance method. Scheffe's post-hoc multiple comparison tests were used to determine significant differences between the materials, the LCU, and the tip distances. Results: The highest DC (70.17) was shown by Filtek Bulk Fill Posterior at a distance of 0 mm, whereas the lowest DC (45.99) was measured for the conventional Filtek Z350 XT at a 4 mm distance. Moreover, higher VMNs were shown by Filtek Bulk Fill and Filtek Z350 composites at 0 mm distance than by the Tetric N-Ceram Bulk Fill composite material when cured with a Bluephase G2 LCU. For all materials, a significant decrease in the DC and mean VMN values was observed at a 4 mm distance in comparison with 0 and 2 mm distances. Conclusions: The DC and VMN values among the studied bulk fill materials were more significantly affected by the material composition and curing protocols. The increased distance from the light tip has a detrimental effect on the mechanical properties of composite resin materials. Significant differences were observed in the curing efficiency of the two LCUs investigated. (©Operative Dentistry, 2022.)
Databáze:	MEDLINE
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