Using a professional DSLR camera to measure total shrinkage of resin composites

Abstract This study evaluated the optical method for measuring free total shrinkage using a Digital Single Lens Reflex (DSLR) camera. Eight composites were evaluated, conventional, bulk fill and low-shrinkage: Z100 (3M Oral Care), Gradia Direct Anterior (GC corporation), Spectra Smart (Dentsply), Filtek Z350 XT (3M Oral Care), Aura Bulk Fill (SDI), Vittra APS (FGM), Opus Bulk Fill APS (FGM), and Beautifil II LS (Shofu Inc.). The samples (6 mm diameter and 1.5 mm thick, n = 10) were placed on a polyvinylsiloxane impression material. An image of the uncured sample was captured using a DSLR camera with 105 mm macro lens and a ring flash. Samples were light cured with a 700 mW/cm2 LED light-cure unit for 40s. Post-polymerization images were captured at 2, 10 and 60 min. Projected circumferential areas of the specimens were drawn using the ImageJ software. Volumetric total shrinkage was calculated from the ratio of the areas obtained from pre- and post-curing. Results were analyzed using One-way ANOVA (α = 0.05) and Tukey test. Volumetric total shrinkage values were significantly different among the composite materials (p < .001). The volumetric shrinkage (%) mean and results of Tukey test at 60 min were: Z100: 3.45±0.30 (A); Gradia Direct Anterior: 3.00 ± 0.23 (B); Spectra Smart 2.89 ± 0.35 (B); Filtek Z350 XT: 2.65 ± 0.37 (BC); Aura Bulk Fill: 2.42 ± 0.25 (CD); Vittra APS: 2.14 ± 0.35 (DE); Opus Bulk Fill APS: 1.91 ± 0.24 (E); Beautifil II LS: 1.18 ± 0.16 (F). The optical method using a DSLR camera, was suitable for total shrinkage evaluation and will allow assessment of total shrinkage without the need for specialized equipment.摘要 本研究评估了使用数码单镜反光相机（Digital Single Lens Reflex, DSLR）测量自由总收缩量的光学方法。本次共评估8种复合树脂材料，涵盖传统型、大块充填型与低收缩型三类：Z100（3M口腔护理（3M Oral Care））、Gradia Direct Anterior（GC公司（GC corporation））、Spectra Smart（登士柏（Dentsply））、Filtek Z350 XT（3M口腔护理（3M Oral Care））、Aura Bulk Fill（SDI公司）、Vittra APS（FGM公司）、Opus Bulk Fill APS（FGM公司）以及Beautifil II LS（松风公司（Shofu Inc.））。实验样本规格为直径6 mm、厚度1.5 mm（n=10），将其置于聚乙烯硅氧烷印模材料上。使用搭载105 mm微距镜头与环形闪光灯的DSLR相机采集未固化样本的图像。采用输出功率700 mW/cm²的LED光固化机对样本进行40秒光固化处理。分别于固化后2 min、10 min及60 min采集聚合后图像。使用ImageJ软件勾勒样本的投影周向面积。通过固化前后获取的面积比值计算体积总收缩量。采用单因素方差分析（One-way ANOVA，α=0.05）与Tukey检验对实验结果进行统计分析。结果显示，不同复合树脂材料的体积总收缩量存在显著差异（p < 0.001）。60 min时的体积收缩率（%）均值及Tukey检验分组结果如下：Z100：3.45±0.30（A）；Gradia Direct Anterior：3.00 ± 0.23（B）；Spectra Smart：2.89 ± 0.35（B）；Filtek Z350 XT：2.65 ± 0.37（BC）；Aura Bulk Fill：2.42 ± 0.25（CD）；Vittra APS：2.14 ± 0.35（DE）；Opus Bulk Fill APS：1.91 ± 0.24（E）；Beautifil II LS：1.18 ± 0.16（F）。本研究所采用的DSLR相机光学方法适用于总收缩量评估，无需专用设备即可完成总收缩量的检测。