Evaluation of antibacterial properties and shear bond strength of orthodontic composites containing silver nanoparticles, titanium dioxide nanoparticles and fluoride: An in vitro study.

OBJECTIVE: The study aimed at determining the antibacterial properties of composites containing silver nanoparticles (Ag NPs) or titanium dioxide nanoparticles (TiO2 NPs), and a fluoride-releasing composite against Streptococcus mutans and Lactobacillus acidophilus, and to evaluate the effect on shear bond strength (SBS) of nanoparticles-modified composites. MATERIALS AND METHODS: An orthodontic composite was modified by adding 1% w/w Ag NPs or 1% w/w TiO2 NPs. Composite discs were prepared to evaluate the antibacterial properties of these modified composites against Streptococcus mutans and Lactobacillus acidophilus, using three different antibacterial tests, namely: Disk agar diffusion test, Biofilm inhibition test and eluted component test. For evaluating the shear bond strength, 80 extracted premolars were collected and divided into four groups (n=20 each), which were bonded with stainless steel preadjusted Edgewise brackets, by using these modified composites. Their SBS was then compared with that of the control group, using a universal testing machine. RESULTS: Composite discs containing nanoparticles and fluoride were capable of producing growth inhibition zones for all bacterial types. Results of the biofilm inhibition test showed that all the study groups inhibited the bacterial count, in comparison to the control group. A significant difference of SBS was observed between all groups. CONCLUSION: The antibacterial activity of orthodontic composites modified with Ag and TiO2 nanoparticles was significant, compared with conventional and fluoride-containing composites. The control group showed the highest SBS, followed by fluoride, titanium, and silver groups, with statistically significant difference in mean SBS values among all groups.

Evaluation of antibacterial properties and shear bond strength of orthodontic composites containing silver nanoparticles, titanium dioxide nanoparticles and fluoride: An in vitro study

ABSTRACT Objective: The study aimed at determining the antibacterial properties of composites containing silver nanoparticles (Ag NPs) or titanium dioxide nanoparticles (TiO2 NPs), and a fluoride-releasing composite against Streptococcus mutans and Lactobacillus acidophilus, and to evaluate the effect on shear bond strength (SBS) of nanoparticles-modified composites. Materials and Methods: An orthodontic composite was modified by adding 1% w/w Ag NPs or 1% w/w TiO2 NPs. Composite discs were prepared to evaluate the antibacterial properties of these modified composites against Streptococcus mutans and Lactobacillus acidophilus, using three different antibacterial tests, namely: Disk agar diffusion test, Biofilm inhibition test and eluted component test. For evaluating the shear bond strength, 80 extracted premolars were collected and divided into four groups (n=20 each), which were bonded with stainless steel preadjusted Edgewise brackets, by using these modified composites. Their SBS was then compared with that of the control group, using a universal testing machine. Results: Composite discs containing nanoparticles and fluoride were capable of producing growth inhibition zones for all bacterial types. Results of the biofilm inhibition test showed that all the study groups inhibited the bacterial count, in comparison to the control group. A significant difference of SBS was observed between all groups. Conclusion: The antibacterial activity of orthodontic composites modified with Ag and TiO2 nanoparticles was significant, compared with conventional and fluoride-containing composites. The control group showed the highest SBS, followed by fluoride, titanium, and silver groups, with statistically significant difference in mean SBS values among all groups.

RESUMO Objetivo: O objetivo do presente estudo foi determinar a eficácia das propriedades antibacterianas de compósitos contendo nanopartículas de prata (Ag NPs) ou nanopartículas de dióxido de titânio (TiO2 NPs) e de um compósito com liberação de flúor, contra as bactérias Streptococcus mutans e Lactobacillus acidophilus e, também, avaliar o efeito na resistência ao cisalhamento (RC) desses compósitos modificados com nanopartículas. Métodos: Os compósitos ortodônticos foram modificados pela adição de 1% p/p de Ag NPs e 1% p/p de TiO2 NPs. Discos de compósito foram preparados para avaliar as propriedades antibacterianas desses grupos contra as bactérias Streptococcus mutans e Lactobacillus acidophilus, usando três testes antibacterianos diferentes: teste de disco-difusão em ágar, teste de inibição da formação de biofilme e teste de componentes eluídos. Para avaliar a resistência ao cisalhamento dos compósitos, 80 pré-molares extraídos foram coletados e divididos em quatro grupos, contendo 20 dentes cada. Foram utilizados braquetes Edgewise pré-ajustados de aço inoxidável para colagem nos dentes usando as resinas modificadas. A RC desses compósitos modificados foi comparada à dos grupos controle, usando uma máquina universal de testes. Resultados: Os discos de compósito contendo as nanopartículas e flúor foram capazes de produzir halos de inibição de crescimento para todos os tipos de bactérias. Os resultados do teste de inibição do biofilme mostraram que houve uma redução na contagem de bactérias em relação ao grupo controle. Diferenças significativas na RC foram observadas entre todos os grupos. Conclusão: A atividade antibacteriana dos compósitos ortodônticos modificados com nanopartículas de Ag e TiO2 foi significativa, quando comparada ao compósito convencional e ao compósito com flúor. O grupo controle apresentou a maior RC, seguido pelos grupos Flúor, Titânio e Prata, com diferença estatisticamente significativa nos valores médios da RC entre todos os grupos.