Sampaio Camila S, Atria Pablo J, Rueggeberg Frederick A, Yamaguchi Satoshi, Giannini Marcelo, Coelho Paulo G, Hirata Ronaldo, Puppin-Rontani Regina M
Department of Restorative Dentistry, Dental Materials Area, University of Campinas-Piracicaba Dental School, Avenue Limeira 901, Piracicaba 13414-903, SP, Brazil; Department of Biomaterials and Biomimetics, New York University-NYU College of Dentistry, 433 First Avenue, 10010 New York, NY, USA; Department of Biomaterials, Universidad de Los Andes-College of Dentistry, Avenue Monseñor Alvaro del Portillo, 12455 Santiago, Chile.
Department of Biomaterials and Biomimetics, New York University-NYU College of Dentistry, 433 First Avenue, 10010 New York, NY, USA; Department of Biomaterials, Universidad de Los Andes-College of Dentistry, Avenue Monseñor Alvaro del Portillo, 12455 Santiago, Chile.
Dent Mater. 2017 Jul;33(7):796-804. doi: 10.1016/j.dental.2017.04.010. Epub 2017 May 15.
To evaluate the effect of light-curing wavelengths on composite filler particle displacement, and thus to visualize localized polymerization shrinkage in a resin-based composite (RBC) containing camphorquinone (CQ) and Lucirin TPO (TPO).
Three light-curing units (LCUs) were used to light-cure a RBC containing CQ and TPO: a violet-only, a blue-only, and a dual-wavelength, conventional (Polywave, emitting violet and blue wavelengths simultaneously). Zirconia fillers were added to the RBC to act as filler particle displacement tracers. LCUs were characterized for total emitted power (mW) and spectral irradiant output (mW/cm/nm). 2-mm high, 7-mm diameter silanized glass cylindrical specimens were filled in a single increment with the RBC, and micro-computed tomography (μ-CT) scans were obtained before and after light-curing, according to each LCU (n=6). Filler particle movement identified polymerization shrinkage vectors, traced using software, at five depths (from 0 up to 2mm): top, top-middle, middle, middle-bottom and bottom.
Considering different RBC depths within the same LCU, use of violet-only and conventional LCUs showed filler particle movement decreased with increased depth. Blue-only LCU showed homogeneous filler particle movement along the depths. Considering the effect of different LCUs within the same depth, filler particle movement within LCUs was not statistically different until the middle of the samples (P>.05). However, at the middle-bottom and bottom depths (1.5 and 2mm, respectively), blue-only LCU compared to violet-only LCU showed higher magnitude of displacement vector values (P<.05). Use of the conventional LCU showed filler displacement magnitudes that were not significantly different than blue-only and violet-only LCUs at any depth (P>.05). With respect to the direction of particle movement vectors, use of violet-only LCU showed a greater displacement when close to the incident violet LED; blue-only LCU showed equally distributed particle displacement values within entire depth among the samples; and the conventional LCU showed greater filler displacement closer to the blue LED locations.
Filler particle displacement in a RBC as a result of light-curing is related to localized application of light wavelength and total emitted power of the light emitted on the top surface of the RBC. When the violet LED is present (violet-only and conventional LCUs), filler particle displacement magnitude decreased with increased depth, while results using the blue-only LED show a more consistent pattern of displacement. Clinically, these results correlate to production of different characteristics of curing within a RBC restoration mass, depending on localized wavelengths applied to the irradiated surface.
评估光固化波长对复合填料颗粒位移的影响，从而观察含樟脑醌（CQ）和Lucirin TPO（TPO）的树脂基复合材料（RBC）中的局部聚合收缩情况。
使用三种光固化单元（LCU）对含CQ和TPO的RBC进行光固化：仅发射紫光的、仅发射蓝光的以及双波长常规型（Polywave，同时发射紫光和蓝光）。向RBC中添加氧化锆填料作为填料颗粒位移示踪剂。对LCU的总发射功率（mW）和光谱辐照输出（mW/cm/nm）进行表征。将2毫米高、7毫米直径的硅烷化玻璃圆柱形试样一次性填入RBC，根据每种LCU（n = 6）在光固化前后进行微型计算机断层扫描（μ-CT）。填料颗粒的移动确定了聚合收缩向量，使用软件在五个深度（从0到2毫米）进行追踪：顶部、顶部中间、中间、中间底部和底部。
考虑同一LCU内不同的RBC深度，仅使用紫光和常规LCU时，填料颗粒移动随深度增加而减少。仅使用蓝光的LCU显示填料颗粒在各深度的移动均匀。考虑同一深度下不同LCU的影响，在样品中部之前，LCU内填料颗粒的移动在统计学上无差异（P>0.05）。然而，在中间底部和底部深度（分别为1.5毫米和2毫米），仅使用蓝光的LCU与仅使用紫光的LCU相比，位移向量值的幅度更高（P<0.05）。使用常规LCU时，在任何深度下填料位移幅度与仅使用蓝光和仅使用紫光的LCU相比均无显著差异（P>0.05）。关于颗粒移动向量的方向，仅使用紫光的LCU在靠近入射紫光LED时显示出更大的位移；仅使用蓝光的LCU在样品的整个深度内显示出均匀分布的颗粒位移值；常规LCU在靠近蓝光LED位置时显示出更大的填料位移。
光固化导致的RBC中填料颗粒位移与光波长的局部应用以及RBC顶表面发射光的总发射功率有关。当存在紫光LED时（仅紫光和常规LCU），填料颗粒位移幅度随深度增加而减小，而仅使用蓝光LED的结果显示出更一致的位移模式。临床上，这些结果与RBC修复体团块内不同固化特征的产生相关，这取决于照射表面所应用的局部波长。
