Matej Par1, Igor Repusic2, Hrvoje Skenderovic3, Ognjen Milat3, Jelena Spajic2, Zrinka Tarle4. 1. Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, Zagreb, Croatia. mpar@inet.hr. 2. Community Health Center, Zagreb, Croatia. 3. Institute of Physics, Bijenicka cesta 46, Zagreb, Croatia. 4. Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, Zagreb, Croatia.
Abstract
OBJECTIVES: To investigate radiant energy, microhardness, and temperature rise in eight resin composites cured with a blue or violet-blue curing unit, using a curing protocol which exceeded manufacturer recommendations. MATERIALS AND METHODS: Cylindrical composite specimens (d = 8 mm, h = 2 or 4 mm, n = 5 per experimental group) were light-cured for 30 s. Light transmittance through specimens was recorded in real time to calculate radiant energy delivered to the specimen bottom. Vickers microhardness was used to evaluate the polymerization effectiveness at depth. Temperature rise at the bottom of the specimens was measured in real time using a T-type thermocouple. RESULTS: Radiant energy delivered from the blue and violet-blue curing unit amounted to 19.4 and 28.6 J/cm2, which was 19 and 13% lower than specified by the manufacturer. Radiant energies at bottom surfaces (0.2-7.5 J/cm2) were significantly affected by material, thickness, and curing unit. All of the composites reached 80% of maximum microhardness at clinically relevant layer thicknesses. The benefit of using the higher-irradiance violet-blue curing unit was identified only in composites containing alternative photoinitiators. Temperature rise during curing ranged from 4.4 to 9.3 °C and was significantly reduced by curing with the lower-intensity blue curing unit and by increasing layer thickness. CONCLUSION: Curing for 30 s, which can be regarded as extended considering manufacturer specifications, produced radiant energies which are in line with the recommendations from the current scientific literature, leading to adequate curing efficiency and acceptable temperature rise. CLINICAL RELEVANCE: Extended curing time should be used to minimize concerns regarding undercuring of composite restorations.
OBJECTIVES: To investigate radiant energy, microhardness, and temperature rise in eight resin composites cured with a blue or violet-blue curing unit, using a curing protocol which exceeded manufacturer recommendations. MATERIALS AND METHODS: Cylindrical composite specimens (d = 8 mm, h = 2 or 4 mm, n = 5 per experimental group) were light-cured for 30 s. Light transmittance through specimens was recorded in real time to calculate radiant energy delivered to the specimen bottom. Vickers microhardness was used to evaluate the polymerization effectiveness at depth. Temperature rise at the bottom of the specimens was measured in real time using a T-type thermocouple. RESULTS: Radiant energy delivered from the blue and violet-blue curing unit amounted to 19.4 and 28.6 J/cm2, which was 19 and 13% lower than specified by the manufacturer. Radiant energies at bottom surfaces (0.2-7.5 J/cm2) were significantly affected by material, thickness, and curing unit. All of the composites reached 80% of maximum microhardness at clinically relevant layer thicknesses. The benefit of using the higher-irradiance violet-blue curing unit was identified only in composites containing alternative photoinitiators. Temperature rise during curing ranged from 4.4 to 9.3 °C and was significantly reduced by curing with the lower-intensity blue curing unit and by increasing layer thickness. CONCLUSION: Curing for 30 s, which can be regarded as extended considering manufacturer specifications, produced radiant energies which are in line with the recommendations from the current scientific literature, leading to adequate curing efficiency and acceptable temperature rise. CLINICAL RELEVANCE: Extended curing time should be used to minimize concerns regarding undercuring of composite restorations.
Entities:
Keywords:
Microhardness; Monowave; Polywave; Radiant energy; Resin composites; Temperature
Authors: Serge Bouillaguet; Guillaume Caillot; Jacques Forchelet; Maria Cattani-Lorente; John C Wataha; Ivo Krejci Journal: J Biomed Mater Res B Appl Biomater Date: 2005-02-15 Impact factor: 3.368
Authors: Vesna Miletic; Pong Pongprueksa; Jan De Munck; Neil R Brooks; Bart Van Meerbeek Journal: Clin Oral Investig Date: 2016-07-06 Impact factor: 3.573