Prospects of Using Gum Arabic Silver Nanoparticles in Toothpaste to Prevent Dental Caries

Abstract

There is growing interest in the use of green synthesized silver nanoparticles (AgNPs) to control and prevent dental diseases. The incorporation of green synthesized AgNPs into dentifrices to reduce pathogenic oral microbes is motivated by their presumed biocompatibility and broad-spectrum antimicrobial activity. In the present study, gum arabic AgNPs (GA-AgNPs) were formulated into a toothpaste (TP) using a commercial TP at a non-active concentration, to produce GA-AgNPs_TP. The TP was selected after evaluating the antimicrobial activity of four commercial TPs 1-4 on selected oral microbes using agar disc diffusion and microdilution assays. The less active TP-1 was then used in the formulation of GA-AgNPs_TP-1; thereafter, the antimicrobial activity of GA-AgNPs_0.4g was compared to GA-AgNPs_TP-1. The cytotoxicity of GA-AgNPs_0.4g and GA-AgNPs_TP-1 was also assessed on the buccal mucosa fibroblast (BMF) cells using the MTT assay. The study demonstrated that antimicrobial activity of GA-AgNPs_0.4g was retained after being combined with a sub-lethal or inactive concentration of TP-1. The non-selective antimicrobial activity and cytotoxicity of both GA-AgNPs_0.4g and GA-AgNPs_TP-1 was demonstrated to be time and concentration dependent. These activities were instant, reducing microbial and BMF cell growth in less than one hour of exposure. However, the use of dentifrice commonly takes 2 min and rinsed off thereafter, which could prevent damage to the oral mucosa. Although, GA-AgNPs_TP-1 has a good prospect as a TP or oral healthcare product, more studies are required to further improve the biocompatibility of this formulation.

Keywords: antimicrobial; cytotoxicity; green synthesis; gum arabic; silver nanoparticles; toothpaste.

Scheme 1

Steps towards GA-AgNPs-TP formulation, investigation of the antimicrobial and cytotoxicity activities. Step 1—screening of commercial TP antimicrobial activity. Step 2—formulation of GA-AgNPs based TP using a TP with least antimicrobial activity.

Figure 1

CFU count and MIC of TP-1 and TP-3 on S. mutans. p ≤ 0.05 was considered as statistically significant, *** p ≤ 0.001.

Figure 2

Cytotoxicity effects of GA-AgNPs_0.4g and GA-AgNPs_TP-1 on BMF cells. Cell viability was assessed by MTT assay after treatment for 24 h. p ≤ 0.05 was considered as statistically significant, ** p ≤ 0.01.

Figure 3

Cytotoxicity effects of GA-AgNPs_TP-1 compared to TCM on BMF cells. Cell viability was assessed by MTT assay after treatment with 25 (A), 50 (B) and 100 (C) µg/mL for various time points up to 24 h. p ≤ 0.05 was considered as statistically significant, ** p ≤ 0.01 and *** p ≤ 0.001.

Figure 4

Comparison of the survival of S. mutans versus BMF cells after exposure to GA-AgNPs_TP-1. S. mutans and BMF cells were treated with 25 (A), 50 (B) and 100 (C) µg/mL for various time points up to 24 h. Viability was evaluated by MTT assay. The green arrow points at an equivalence point of the GA-AgNPs_TP-1. p ≤ 0.05 was considered as statistically significant, ** p ≤ 0.01 and *** p ≤ 0.001.