Shear bond strength, adhesive remnant index, and anti-biofilm effects of photoexcited a modified orthodontic adhesive containing curcumin doped poly lactic-co-glycolic acid nanoparticles; An ex-vivo biofilm model of S. mutans on the enamel slab bonded brackets

Shear bond strength, adhesive remnant index, and anti-biofilm effects of photoexcited a modified orthodontic adhesive containing curcumin doped poly lactic-co-glycolic acid nanoparticles; An ex-vivo biofilm model of <em>S. mutans</em> on the enamel slab bonded brackets:

Publication date: Available online 26 January 2020

Source: Photodiagnosis and Photodynamic Therapy

Author(s): Hanie Ahmadi, Vahid Haddadi-Asl, Hassan-Ali Ghafari, Roghayeh Ghorbanzadeh, Yasaman Mazlum, Abbas Bahador

Abstract

Background

Potential complications during fixed orthodontic procedures are white spot lesions (WSLs) and tooth decay. This study evaluated the anti-biofilm activity of an orthodontic adhesive (OA) incorporating curcumin (Cur) doped Poly lactic-co-glycolic acid nanoparticles (Cur-PLGA-NPs), which can have the highest concentration of Cur-PLGA-NPs and shear bond strength (SBS) value simultaneously, against cariogenic bacteria i.e., Streptococcus mutans.

Materials and methods

Following synthesis and confirmation of Cur-PLGA-NPs, SBS and adhesive remnant index (ARI) of the modified orthodontic adhesives (MOA) containing Cur-PLGA-NPs (3, 5, 7, and 10% wt.) were measured using universal testing machine and stereomicroscope, respectively. After artificial aging (continuously rinsed up to 180 days), the residual anti-biofilm ability of MOA which can have the highest concentration of Cur-PLGA-NPs and SBS value simultaneously were determined by anti-biofilm assay following photoexcited enamel slab bonded brackets by MOA containing Cur-PLGA-NPs against S. mutans biofilms using crystal violet assay.

Results

Adhesive with 7% wt. Cur-PLGA-NPs revealed the highest concentration of Cur-PLGA-NPs and SBS value (16.19 ± 2.69 MPa, P < 0.05) simultaneously. No statistically significant difference in ARI scores was observed between the MOA and control (Transbond XT without the Cur-PLGA-NPs). On days 15, 30, 60, 90 and 120 there was a considerable decrease in optical density (OD) of preformed S. mutans biofilms on photoexcited enamel slab bonded brackets using MOA containing 7% wt. Cur-PLGA-NPs, to 94.1%, 79.6%, 69.6%, 69.4%, and, 55.1% respectively in comparison to the control group (all, P < 0.05). From days 150 onwards, microbial biofilm formation was progressively increased on enamel slab bonded brackets using MOA containing 7% wt. Cur-PLGA-NPs compared to the control group (OA). Although chlorhexidine (2%; as positive control) showed significant activity against pre-formed S. mutans biofilms on enamel slab bonded brackets using OA (99.1% biofilm reduction; P = 0.001), its activity was slightly higher but not significant than photoexcited enamel slab bonded brackets using MOA containing 7% wt. Cur-PLGA-NPs on the days 15 and 30 (both, P > 0.05).

Conclusions

The 7% wt. Cur-PLGA-NPs can serve as an orthodontic adhesive antimicrobial additive as exposure to blue laser provides an acceptable antimicrobial effect against cariogenic bacteria for a considerable time.

Graphical abstract