Seung-Hoon Han1, Alireza Sadr2, Yasushi Shimada3, Junji Tagami4, Sung-Ho Park5. 1. Department of Conservative Dentistry, St. Vincent Hospital, College of Medicine, Catholic University of Korea, #93 Jungbu-daero, Paldal-gu, Suwon, Gyeonggi-do, South Korea. Electronic address: han7537@hotmail.com. 2. Department of Restorative Dentistry, School of Dentistry, University of Washington, 1959 NE Pacific St, B162, Seattle, WA, USA. Electronic address: arsadr@uw.edu. 3. Department of Operative Dentistry, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama, 700-8525, Japan; Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 1-5-45, Japan. Electronic address: shimada.ope@okayama-u.ac.jp. 4. Department of Cariology and Operative Dentistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 1-5-45, Japan. Electronic address: tagami.ope@tmd.ac.jp. 5. Department of Conservative Dentistry, Oral Science Research Center, College of Dentistry, Yonsei University, #50 Yonsei- ro, Seodaemun-gu, Seoul, Republic of Korea. Electronic address: sunghopark@yuhs.ac.
Abstract
OBJECTIVES: The purpose of this study was to compare the internal adaptation of resin composite restorations in Class I cavities with or without an intermediate layer, and to identify the relationships between the internal adaptation and the polymerization shrinkage parameters of the layer material. METHODS: Class I cavities prepared in human third molars were treated with a one-step self-etch adhesive (G-Premio Bond, GC). In the control group, Tetric-EvoCeram Bulk-Fill (TBF, Ivoclar Vivadent) was placed using the bulk-fill technique and then light-cured. In the experimental groups, six different layer materials (three flowable resin composites, two bulk-fill resin composites, and a resin-modified glass-ionomer) were applied to a 1.5-mm thickness and light-cured, which was followed by TBF filling. After thermo-cycling, internal adaptation was measured using swept-source optical coherence tomography (SS-OCT) imaging and compared in terms of high brightness percentage (HB%) to represent the microgap. Shrinkage strain (SS), flexural modulus (FM), and polymerization shrinkage stress of the intermediate layer-resin composite complex (PS) were measured for each material. The relationships among HB%, SS, FM, and PS were evaluated statistically. RESULTS: Groups with an intermediate layer showed lower HB% than the control group. The HB% correlated with PS (Pearson's correlation: R2 = 0.883, p < 0.05), and the PS correlated with the product of SS and FM. CONCLUSION: Internal adaptation depended on the polymerization shrinkage stress of the intermediate layer-resin composite complex. CLINICAL SIGNIFICANCE: Bulk-fill resin composite, which can show low polymerization shrinkage stress, may be used as an intermediate layer for better internal adaptation.
OBJECTIVES: The purpose of this study was to compare the internal adaptation of resin composite restorations in Class I cavities with or without an intermediate layer, and to identify the relationships between the internal adaptation and the polymerization shrinkage parameters of the layer material. METHODS: Class I cavities prepared in human third molars were treated with a one-step self-etch adhesive (G-Premio Bond, GC). In the control group, Tetric-EvoCeram Bulk-Fill (TBF, Ivoclar Vivadent) was placed using the bulk-fill technique and then light-cured. In the experimental groups, six different layer materials (three flowable resin composites, two bulk-fill resin composites, and a resin-modified glass-ionomer) were applied to a 1.5-mm thickness and light-cured, which was followed by TBF filling. After thermo-cycling, internal adaptation was measured using swept-source optical coherence tomography (SS-OCT) imaging and compared in terms of high brightness percentage (HB%) to represent the microgap. Shrinkage strain (SS), flexural modulus (FM), and polymerization shrinkage stress of the intermediate layer-resin composite complex (PS) were measured for each material. The relationships among HB%, SS, FM, and PS were evaluated statistically. RESULTS: Groups with an intermediate layer showed lower HB% than the control group. The HB% correlated with PS (Pearson's correlation: R2 = 0.883, p < 0.05), and the PS correlated with the product of SS and FM. CONCLUSION: Internal adaptation depended on the polymerization shrinkage stress of the intermediate layer-resin composite complex. CLINICAL SIGNIFICANCE: Bulk-fill resin composite, which can show low polymerization shrinkage stress, may be used as an intermediate layer for better internal adaptation.
Authors: Marwa Abdelaziz; Andrés F Zuluaga; Francesco Betancourt; Daniel Fried; Ivo Krejci; Tissiana Bortolotto Journal: Proc SPIE Int Soc Opt Eng Date: 2020-02-19