The aims of this study were: To evaluate the surface hardness of simulated dentin caries lesions treated with either silver nanoclusters (AgNCls) synthesized in polymethacrylic acid (PMAA) or 38% silver diammine fluoride (SDF), as well as observe the penetration of the treatment solutions into the simulated caries lesions. Dentin blocks 4 mm thick obtained from caries-free third molars were sectioned and then simulated caries lesions on the occlusal dentin surfaces were created. Each specimen (n = 8) was divided into four sections: (A) treated with 20% AgNCls/PMAA; (B) treated with SDF 38% (FAgamin, Tedequim, Cordoba, Argentina); (C) sound tooth protected by nail-varnish during artificial caries generation (positive control); and (D) artificial caries lesion without surface treatment (negative control). AgNCls/PMAA or SDF were applied on the simulated lesions with a microbrush for 10 s, then excess removed. The surface hardness was measured by means of Vickers indentation test. To trace the depth of penetration, up to 400 μm, of silver ions, elemental composition of the samples was observed using EDX, coupled with SEM, and measured every 50 μm from the surface towards the pulp chamber. Laser Induced Breakdown Spectroscopy (LIBS) was also employed to trace silver ion penetration; the atomic silver line 328.06 nm was used with a 60 μm laser spot size to a depth of 240 μm. Student’s-t test identified significant differences between treatment groups for each depth and the Bonferroni test was used for statistical analysis of all groups (p < 0.05). Mean surface hardness values obtained were 111.2 MPa, 72.3 MPa, 103.3 MPa and 50.5 MPa for groups A, B, C and D respectively. There was a significant difference between groups A and C compared with groups B and D, the group treated with AgNCls/PMAA achieved the highest surface hardness, similar or higher than the sound dentin control. A constant presence of silver was observed throughout the depth of the sample for group A, while group B showed a peak concentration of silver at the surface with a significant drop beyond 50 μm. The 20% AgNCls/PMAA solution applied to simulated dentin caries lesions achieved the recovery of surface hardness equivalent to sound dentin with the penetration of silver ions throughout the depth of the lesion.

本研究的目的是：评估用聚甲基丙烯酸（PMAA）或38%氟化二氨银（SDF）合成的银纳米簇（AgNCls）治疗的模拟牙本质龋病病变的表面硬度，并观察纳米银簇（AgNCls）的渗透性。将治疗溶液注入模拟的龋病病变中。从无龋齿的第三磨牙中获得4毫米厚的牙本质块，进行切片，然后在咬合牙本质表面上创建模拟龋损病变。每个样本 (n = 8) 分为四个部分： (A) 用 20% AgNCls/PMAA 处理； (B) 用 SDF 38% 处理（FAgamin、Tedequim、科尔多瓦、阿根廷）； (C) 人工龋齿生成过程中受指甲油保护的健康牙齿（阳性对照）； (D)未经表面处理的人工龋损病变(阴性对照)。用微刷将 AgNCls/PMAA 或 SDF 涂在模拟病变上 10 秒，然后去除多余的。表面硬度通过维氏压痕试验来测量。为了追踪银离子的渗透深度（高达 400 μm），使用 EDX 结合 SEM 观察样品的元素组成，并从表面到牙髓室每隔 50 μm 进行测量。激光诱导击穿光谱 (LIBS) 也被用来追踪银离子的渗透；使用原子银线 328.06 nm，激光光斑尺寸为 60 μm，深度为 240 μm。 Student's -t检验确定了每个深度的治疗组之间存在显着差异，并且使用 Bonferroni 检验对所有组进行统计分析 (p < 0.05)。 A、B、C 和 D 组的平均表面硬度值分别为 111.2 MPa、72.3 MPa、103.3 MPa 和 50.5 MPa。 A组和C组与B组和D组相比有显着差异，AgNCls/PMAA处理组达到最高表面硬度，与健全牙本质对照相似或更高。在 A 组的整个样品深度中观察到银的持续存在，而 B 组则在表面出现银的峰值浓度，并在超过 50 μm 处显着下降。将20％AgNCls/PMAA溶液应用于模拟牙本质龋损，随着银离子渗透到整个病变深度，表面硬度恢复到与健全牙本质相当。