A Chemical Approach to Optimizing Bioactive Glass Dental Composites

Abstract

The chemical microenvironment surrounding dental composites plays a crucial role in controlling the bacteria grown on these specialized surfaces. In this study, we report a scanning electrochemical microscopy (SECM)-based analytic technique to design and optimize metal ion-releasing bioactive glass (BAG) composites, which showed a significant reduction in biofilm growth. SECM allows positioning of the probe without touching the substrate while mapping the chemical parameters in 3-dimensional space above the substrate. Using SECM and a solid-state H + and Ca 2+ ion-selective microprobe, we determined that the local Ca 2+ concentration released by different composites was 10 to 224 µM for a BAG particle size of <5 to 150 µm in the presence of artificial saliva at pH 4.5. The local pH was constant above the composites in the same saliva solution. The released amount of Ca 2+ was determined to be maximal for particles <38 µm and a BAG volume fraction of 0.32. This optimized BAG-resin composite also showed significant inhibition of biofilm growth (24 ± 5 µm) in comparison with resin-only composites (53 ± 6 µm) after Streptococcus mutans bacteria were grown for 3 d in a basal medium mucin solution. Biofilm morphology and its subsequent volume, as determined by the SECM imaging technique, was (0.59 ± 0.38) × 10 7 µm 3 for BAG-resin composites and (1.29 ± 0.53) × 10 7 µm 3 for resin-only composites. This study thus lays the foundation for a new analytic technique for designing dental composites that are based on the chemical microenvironment created by biomaterials to which bacteria have been exposed.

Scanning electrochemical microscopy and its potential for studying biofilms and antimicrobial coatings

“…Quorum quenching enzymes [110], adhesin repressors [111], nanoparticle-based copolymers [56,112] and metal-chelator approaches [113,114] have been studied so far to prevent biofilm formation or to eradicate biofilms. To date, only a few studies concerning antimicrobial effects have been published using SECM [82,112,115,116]. Silver nanoparticles (AgNPs) and Ag(I) at low concentrations are known as a very powerful antimicrobial agent, which, to date, are used in many consumer products and clinical applications [117].…”

Addition of antibacterial agent effect on color stability of composites after immersion of different beverages

“…Centuries ago, various metals, such as silver, gold, and zinc, were used as bactericidal and bacteriostatic agents . Today, to address the aforementioned problems, antibacterial composites and adhesive systems have been developed, with various approaches used to confer antibacterial activity . In terms of resin‐based dental composites, one approach is to include antibacterial agents, such as fluoride and chlorhexidine, in the resin matrix.…”

“…These include stimulating bone formation, desensitizing teeth, remineralizing white spot lesions, and restoring teeth. A recent study reported that the release of metal ions by BAG impeded the formation of oral biofilms . The authors of the study recommended that BAG should be added to composites.…”

“…8 Today, to address the aforementioned problems, antibacterial composites and adhesive systems have been developed, with various approaches used to confer antibacterial activity. 9 In terms of resin-based dental composites, one approach is to include antibacterial agents, such as fluoride and chlorhexidine, in the resin matrix. These agents are then released over time, inhibiting bacterial growth.…”

“…A recent study reported that the release of metal ions by BAG impeded the formation of oral biofilms. 9 The authors of the study recommended that BAG should be added to composites. Other research reported that nano-zinc silicium (NZS), which combined the effects of zinc-oxide antibacterial nanoparticles and silicium-oxide nanoparticles, reduced bacterial penetration of dental plaque.…”