The synergistic effect of Nano-propolis and curcumin-based photodynamic therapy on remineralization of white spot lesions: An ex vivo study

One of the major problems in fixed orthodontic treatments is the control of enamel demineralization, white spots lesions (WSL), and dental caries around the brackets, which can be stopped by strengthening the remineralization process. The aim of this study was to investigate the synergistic effect of propolis nanoparticles (NPro) and nano-curcumin-based photodynamic therapy (NCur-PDT) in the remineralization of WSL ex vivo.Experimental period was 5.5 months. After synthesis and characterization of NPro, the extracted bovine teeth were demineralized using a demineralization solution. They were divided into 7 groups (n=10) and treated in the following groups: 1) Negative control (artificial saliva), 2) Positive control or control of treatment (2% neutral sodium fluoride gel; NSF), 3) Nano-curcumin (NCur), 4) NPro, 5) Diode laser irradiation (light), 6) NCur with irradiation (NCur-PDT) and 7) NPro plus NCur-PDT (NPro+NCur-PDT). The treatment duration was 3 months and each treatment was conducted on T1 (the end of the third week), T2 (the end of the sixth week), T3 (the end of the ninth week), and T4 (the end of the twelfth week). Then, the microhardness, surface changes, and surface topography of the enamel were examined using digital hardness tester, DIAGNOdent Pen Reading, and scanning electron microscope (SEM), respectively.In all groups, after demineralization, the microhardness of tooth enamel decreased and after each of the treatments, the amount of microhardness significantly increased over time except light and artificial saliva groups. The earliest significant change in microhardness improvement was observed in the NPro+NCur-PDT group at T2 (P<0.05). Also, at T2, DIAGNODent Pen revealed the earliest significant improved change in the level of mineralization degree in the NPro+NCur-PDT group. NCur and light irradiation groups alone, like the control group (artificial saliva), did not lead to remineralization (P>0.05). Also, the NPro+NCur-PDT treatment results obtained from SEM after the last treatment in the twelfth week showed that remineralization in that group has significantly improved compared to other groups.The results of this study showed that combined use of NPro and NCur-PDT had more enamel remineralization efficacy in a shorter period. Simultaneous application of NPro and NCur-PDT had also a stronger therapeutic effect after 3 months.