Oh Soram, Kim Hyun Ju, Kim Hyun-Jung, Antonson Sibel A, Kim Sun-Young
Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, 1 Hoe-gi-dong, Dongdaemoon-gu, Seoul, 02447, Korea.
Department of Periodontics, Seoul National University Dental Hospital, 101 Daehakno, Jongno-gu, Seoul, 03080, Korea.
Biomater Res. 2022 May 20;26(1):18. doi: 10.1186/s40824-022-00267-5.
The aim of this study was to evaluate the influence of increased irradiation distance on the flexural strength (FS), dentin micro-shear bond strength (μSBS), and the degree of conversion (DC) of bulk-fill flowable, conventional flowable, and packable resin composites.
The resin composites tested were Surefil® SDR™ (SDR), Filtek Z350 XT Flowable Restorative A2 shade (Z3F), and Filtek Z350 XT Universal Restorative A2 shade (Z3P). Specimens were cured at four irradiation distances (0, 2, 4, and 8 mm) with an Elipar DeepCure-S LED curing light for 20 s. FS tests were performed (n = 15) using bar-shaped specimens (8 mm × 2 mm × 2 mm) of the resin composites. μSBS tests were performed on the occlusal surfaces of extracted third molars from humans that were ground to expose dentin (n = 15). DC was measured by using Raman spectroscopy on the top and bottom surfaces of disk specimens (2-mm thick) (n = 3). To further investigate whether extended irradiation times could compensate for reduced irradiance, additional Z3P specimens were prepared, which were light-cured at 8-mm distances for 40 and 60 s and subjected to FS tests, μSBS tests, and Raman spectroscopy. Both two-way and one-way ANOVA were used for statistical analyses.
Both FS and DC of Z3P specimens cured at an 8-mm distance were significantly lower than those cured at shorter distances (p < 0.05), whereas the FS and DC of the Z3F and SDR specimens were not significantly influenced by increasing distances. The μSBSs of the three types of resin composites reduced with increasing irradiation distances. The FS, μSBS, and DC of the Z3P specimen light-cured at 8 mm for 40 s were comparable to those of the Z3P specimen cured at 0 mm for 20 s.
Increasing the irradiation distance to 8 mm can have a deleterious influence on mechanical performances, including the FS, DC, and dentin μSBS, of the resin composites polymerized with high-irradiance light curing units.
本研究的目的是评估增加照射距离对大块充填可流动树脂复合材料、传统可流动树脂复合材料和可压实树脂复合材料的弯曲强度（FS）、牙本质微剪切粘结强度（μSBS）以及转化率（DC）的影响。
测试的树脂复合材料为Surefil® SDR™（SDR）、Filtek Z350 XT可流动修复体A2色（Z3F）和Filtek Z350 XT通用修复体A2色（Z3P）。使用Elipar DeepCure-S LED固化灯在四个照射距离（0、2、4和8毫米）下对样本进行20秒的固化。使用树脂复合材料的条形样本（8毫米×2毫米×2毫米）进行FS测试（n = 15）。对从人类拔除的第三磨牙的咬合面进行研磨以暴露牙本质后进行μSBS测试（n = 15）。使用拉曼光谱法在圆盘样本（2毫米厚）的顶面和底面测量DC（n = 3）。为了进一步研究延长照射时间是否可以弥补辐照度的降低，制备了额外的Z3P样本，将其在8毫米距离下光固化40秒和60秒，并进行FS测试、μSBS测试和拉曼光谱分析。双向方差分析和单向方差分析均用于统计分析。
在8毫米距离下固化的Z3P样本的FS和DC均显著低于在较短距离下固化的样本（p < 0.05），而Z3F和SDR样本的FS和DC不受距离增加的显著影响。三种类型的树脂复合材料的μSBS随着照射距离的增加而降低。在8毫米处光固化40秒的Z3P样本的FS、μSBS和DC与在0毫米处光固化20秒的Z3P样本相当。
将照射距离增加到8毫米会对使用高辐照度光固化装置聚合的树脂复合材料的机械性能产生有害影响，包括FS、DC和牙本质μSBS。
