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.

Effect of pharmacological agents on relapse following orthodontic tooth movement.

OBJECTIVES: To investigate and synthesize systematically the evidence from animal studies pertaining to the effect of pharmacological agents on tooth movement relapse following cessation of orthodontic force application. MATERIALS AND METHODS: An electronic search was conducted in seven online databases (including gray sources) without restrictions until the third week of April 2019, followed by a hand search in the reference lists of eligible articles. Controlled animal studies investigating the effect of pharmacological agents on tooth movement relapse following orthodontic treatment were selected. Relevant data were extracted from eligible studies and the risk of bias assessment was done using SYRCLE's risk of bias tool. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool. RESULTS: The search identified 2354 records, of which 7 studies were deemed eligible for inclusion in the qualitative synthesis, with the majority presenting an unclear risk of bias. Orthodontic relapse was shown to decrease with the administration of pamidronate disodium, atorvastatin, aspirin, and chemically modified tetracycline-3. Inconsistent effects on relapse were observed after the use of simvastatin. The overall quality of retrieved evidence was assessed as low at best. CONCLUSIONS: The available evidence shows that the investigated pharmacological agents may demonstrate variable effects on tooth movement relapse following cessation of orthodontic force. Additional evidence of higher quality is required to draw definitive conclusions on their effects and to make potential recommendations for clinical application.

Antibacterial activity and debonding force of different lingual retainers bonded with conventional composite and nanoparticle containing composite: An in vitro study.

BACKGROUND: To evaluate the antibacterial activity and debonding force of retainers bonded with conventional and nanoparticle (TiO2) containing composite. METHODOLOGY: Antibacterial activity was tested against Streptococcus mutans and Lactobacillus acidophilus using disk agar diffusion, biofilm inhibition, and eluted components tests. For the eluted components test, colony counts of bacteria were tested on 0, 3, and 30 days. Three different retainers were bonded to the lingual surface of extracted lower incisors using conventional and 1% TiO2 composite. Samples were divided as follows: Group 1: 1a, stainless steel retainer (Bond-a-Braid) with conventional composite, and 1b, stainless steel retainer with nanoparticle composite; Group 2: 2a, titanium retainer with conventional composite, and 2b, titanium retainer with nanoparticle composite; Group 3: 3a, fiber-reinforced retainer (Interlig) with conventional composite, and 3b, fiber-reinforced retainer with nanoparticle composite. The Instron stereomicroscope was used to test debonding force and failure sites respectively. RESULTS: In the disk agar diffusion test, TiO2 composite has shown more inhibition zones. Biofilm inhibition test showed a significant decrease in colony counts of both organisms in the TiO2 group. The eluted component test showed a significant decrease in colony counts from day 0 to day 30 in the TiO2 group compared with the control group. The highest debonding force was observed in stainless steel retainers with conventional composite, and lowest in fiber-reinforced composite retainers with TiO2 composite, with no significant difference in Adhesive Remnant Index scores. CONCLUSION: The TiO2 composite group showed greater antibacterial activity without compromising the bond strength, which was statistically significant. Compared with other groups, stainless steel wires bonded with conventional composite showed the highest debonding force.