Spectrophotometric analysis of crown discoloration following the use of silver nanoparticles combined with calcium hydroxide as intracanal medicament

BACKGROUND: Optimal antibacterial efficacy of intracanal medicaments containing silver nanoparticles (Ag-NPs) has been well documented. However, concerns remain regarding the effect of Ag-NPs on tooth color. This study aimed to assess the effects of calcium hydroxide (CH) mixed with Ag-NPs as intracanal medicaments on tooth color. The effect of location of application of medicament on the degree of discoloration was evaluated as well. MATERIAL AND METHODS: Fifty extracted single-rooted, single-canal human teeth with straight roots, no caries, no cracks or fractures were collected and accessed. After cleaning and shaping of the root canals, the teeth were randomly divided into two experimental groups (n=20) with CH and CH plus Ag-NPs as intracanal medicaments and a control group of saline (n=10). Experimental groups were randomly divided into two equal subgroups of A, where medicament was applied below the cemento enamel junction (CEJ) and B where the medicament was applied to the root canal and pulp chamber. Color change (ΔE) was assessed using a spectrophotometer in CIELAB system at five time points of beforemedicaments application (T0), immediately medicaments placement (T1), one week (T2), one month (T3) and three months (T4) after the application of medicaments. Data were analyzed using two-way and three-way ANOVA. RESULTS: Color change in Ag-NPs plus CH and CH groups was not significantly different at any time point (P=0.23). Increased exposure time in both groups did not increase the ΔE (P >0.05). Significant differences were noted in ΔE between subgroups A and B (P<0.05). CONCLUSIONS: Addition of Ag-NPs to CH caused no significant change in tooth color compared to the application of CH alone. However, its use must be limited to the root canal space only. Key words:Silver nanoparticles, color change, calcium hydroxide, spectrophotometry, intracanal medicament.