Mindy M Daugherty1, Wen Lien2, Michael R Mansell3, Douglas L Risk4, Daniel A Savett5, Kraig S Vandewalle6. 1. United States Army, 36014 Wratten Loop, Ft. Hood, TX 76544, USA. Electronic address: mindy.m.daugherty.mil@mail.mil. 2. United States Air Force, 3650 Chambers Pass, Ft. Sam Houston, TX 78023, USA. Electronic address: wen.lien.mil@mail.mil. 3. United States Army, 36014 Wratten Loop, Ft. Hood, TX 76544, USA. Electronic address: michael.r.mansell.mil@mail.mil. 4. United States Air Force, 3650 Chambers Pass, Ft. Sam Houston, TX 78023, USA. Electronic address: drisk@amdpi.com. 5. United States Air Force, 3650 Chambers Pass, Ft. Sam Houston, TX 78023, USA. Electronic address: daniel.a.savett.mil@mail.mil. 6. United States Air Force, 1615 Truemper St., Joint Base San Antonio - Lackland, TX 78236, USA. Electronic address: kraig.s.vandewalle.civ@mail.mil.
Abstract
OBJECTIVES: The purpose of this study was to investigate the effect of high-irradiance light-curing-units (LCUs) on the depth-of-cure (DoC) and degree-of-polymerization (DoP) of bulk-fill composites (BFCs). METHODS: The DoC of composites (Beautifil-Bulk, SHOFU; Filtek-Bulk-Fill, 3M ESPE; Tetric-EvoCeram-Bulk-Fill, Ivoclar; Sonic-Fill-2, Kerr; Venus-Bulk-Fill, Heraeus; Z250, 3M-ESPE) were measured according to ISO-4049 using high-irradiance LCUs (FlashMax-P3, CMS-Dental; SPEC3, Coltene) and conventional LCU (Paradigm, 3M-ESPE) for exposure times: 3/9-s, 3/20-s, and 10/20-s respectively. Using FTIR, the DoP per composite was measured at the bottom surface as a function of post-curing times for the LCUs at the same exposure times. Data was analyzed with nonlinear regression and ANOVA/Tukey. RESULTS: Significant differences in DoC were found amongst the LCUs for the various exposure times. All BFCs failed to meet the DoC claimed by manufacturers and failed to satisfy ISO-4049 with the high-irradiance LCUs with 3-s exposures. Standard irradiance and 20-s exposures outperformed all other irradiance-exposure combinations for maximizing the DoC and DoP of BFCs. A minimum of 15.3J/cm2 radiant exposure was required to achieve an adequate maximum polymerization rate. Venus Bulk exhibited the highest DoC and DoP for any LCU-exposure-time combination. SIGNIFICANCE: Among the different combinations of BFCs and LCUs, DoC and DoP were always increased with longer exposure time, but there exists a theoretical radiant-exposure limit beyond which DoP or DoC remains unchanged. However, high DoC or DoP are not always associated with one another. Thus, the exposure-reciprocity law must be approached thoughtfully since irradiance and exposure can independently affect DoP and DoC.
OBJECTIVES: The purpose of this study was to investigate the effect of high-irradiance light-curing-units (LCUs) on the depth-of-cure (DoC) and degree-of-polymerization (DoP) of bulk-fill composites (BFCs). METHODS: The DoC of composites (Beautifil-Bulk, SHOFU; Filtek-Bulk-Fill, 3M ESPE; Tetric-EvoCeram-Bulk-Fill, Ivoclar; Sonic-Fill-2, Kerr; Venus-Bulk-Fill, Heraeus; Z250, 3M-ESPE) were measured according to ISO-4049 using high-irradiance LCUs (FlashMax-P3, CMS-Dental; SPEC3, Coltene) and conventional LCU (Paradigm, 3M-ESPE) for exposure times: 3/9-s, 3/20-s, and 10/20-s respectively. Using FTIR, the DoP per composite was measured at the bottom surface as a function of post-curing times for the LCUs at the same exposure times. Data was analyzed with nonlinear regression and ANOVA/Tukey. RESULTS: Significant differences in DoC were found amongst the LCUs for the various exposure times. All BFCs failed to meet the DoC claimed by manufacturers and failed to satisfy ISO-4049 with the high-irradiance LCUs with 3-s exposures. Standard irradiance and 20-s exposures outperformed all other irradiance-exposure combinations for maximizing the DoC and DoP of BFCs. A minimum of 15.3J/cm2 radiant exposure was required to achieve an adequate maximum polymerization rate. Venus Bulk exhibited the highest DoC and DoP for any LCU-exposure-time combination. SIGNIFICANCE: Among the different combinations of BFCs and LCUs, DoC and DoP were always increased with longer exposure time, but there exists a theoretical radiant-exposure limit beyond which DoP or DoC remains unchanged. However, high DoC or DoP are not always associated with one another. Thus, the exposure-reciprocity law must be approached thoughtfully since irradiance and exposure can independently affect DoP and DoC.
Authors: Franco Mauricio; Julia Medina; Luzmila Vilchez; Oscar Sotomayor; César Muricio-Vilchez; Frank Mayta-Tovalino Journal: J Int Soc Prev Community Dent Date: 2021-04-15