Department of Operative Dentistry, Endodontics, and Dental Materials, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil,
Department of Restorative Dentistry, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
Am J Dent. 2022 Aug;35(4):172-177.
To evaluate the hardness profile of three resin-based restorative composites (RBC) (Filtek Z250XT, Filtek One Bulk Fill, Filtek Bulk Fill Flow) polymerized by a multi-wave curing light.
Specimens (n= 12) were prepared by inserting 2 mm RBC increments into a split-mold and polymerized from the top using either 20- or 40-second exposure times. Specimen curing was performed directly at a 1 mm distance (control-group) or through an ivorine-tooth slot preparation at a 5 mm distance (experimental-group). Specimens were stored (37 ± 1°C/24 hours), then subjected to Knoop indenter (25g/5 seconds). Specimens' KHN values were obtained from the upper and lower surfaces. Relative hardness (RH) (lower-to-upper ratio) was calculated for each specimen. Data were analyzed with three-way ANOVA and Tukey's HSD (α= 0.05).
There was no significant RH difference among RBCs in the control group, regardless of the exposure time (P> 0.05). Average RH ratios for all RBCs tested in this group were greater than 0.80. However, the average RH values of the experimental RBC group were significantly lower. The RH for Z250 was 0.39 in the 20-second group, while RH was 0.63 in the 40-second group. BF had an RH ratio of 0.70 in the 20-second and 0.72 in the 40-second group, while One Bulk had a ratio of 0.65 in the 20-second and 0.71 in the 40-second groups. Doubled exposure time substantially increased RH of all tested materials at a 1 mm tip-to-material distance. Clinically relevant 5 mm light-tip to material-surface distance significantly reduced polymerization efficacy of RBC specimens, regardless of the exposure time.
Adequate light-polymerization of resin-based direct restoratives is necessary for long-term clinical success. Polymerizing Class 2 restorations is challenging due to a hard-to-reach location and an increased distance between the light source and the restorative material. Insufficient polymerization is often seen at the bottom of the proximal box of the Class 2 cavity, with a detrimental effect on restoration longevity.
评估三种树脂基修复复合材料（RBC）（Filtek Z250XT、Filtek One Bulk Fill、Filtek Bulk Fill Flow）的硬度分布，这些复合材料均由多波长固化灯聚合而成。
通过将 2mm 的 RBC 增量插入到分体模具中制备样本（n=12），然后从顶部使用 20 秒或 40 秒的曝光时间进行聚合。样本的固化是在距离 1mm 处直接进行（对照组），或者通过在距离 5mm 处的象牙齿槽制备进行（实验组）。样本在（37±1°C/24 小时）下储存，然后用努普压痕仪（25g/5 秒）进行测试。从上下表面获得样本的 KHN 值。计算每个样本的相对硬度（RH）（下表面与上表面的比值）。数据采用三因素方差分析和 Tukey 的 HSD 检验（α=0.05）进行分析。
在对照组中，无论曝光时间如何，三种 RBC 之间的 RH 差异均无统计学意义（P＞0.05）。在该组中测试的所有 RBC 的平均 RH 比值均大于 0.80。然而，实验组 RBC 的平均 RH 值明显较低。在 20 秒组中，Z250 的 RH 为 0.39，而在 40 秒组中，RH 为 0.63。BF 在 20 秒组的 RH 比值为 0.70，在 40 秒组的 RH 比值为 0.72，而 One Bulk 在 20 秒组的 RH 比值为 0.65，在 40 秒组的 RH 比值为 0.71。曝光时间加倍可显著提高所有测试材料在距离材料 1mm 时的 RH。临床相关的 5mm 光尖到材料表面距离显著降低了 RBC 样本的聚合效果，无论曝光时间如何。
树脂基直接修复材料的充分光聚合对于长期临床成功是必要的。由于难以到达的位置和光源与修复材料之间的距离增加，Class 2 修复体的聚合具有挑战性。在 Class 2 腔的近中盒底部经常会出现聚合不足的情况，这会对修复体的寿命产生不利影响。
