Nobio has produced a long awaited advancement in dental restoratives with a new non-releasing, long acting antimicrobial technology.
When William Gies addressed the dental association about dental caries over 100 years ago, it was known that bacteria on the tooth surface creates an acidic environment, causing enamel wear and dentin exposure (Gies, 1918). Consequently, the solution he proposed to prevent tooth decay, was to prevent bacteria accumulation on teeth. And yet, while significant progress has been made in preventing primary caries, still recurrent, or secondary caries, remain most common, exacerbated by the continuing shift from amalgam to composites.
Nobio has produced a long-awaited advancement in dental restoratives with a revolutionary non-releasing antimicrobial technology.
THE CARIES PROCESS
The oral cavity is in a constant state of bio-mineralization, in which minerals, diffuse in and out of the surface of the tooth. When minerals flow out of the tooth surface (demineralization), the structure is weakened. When they flow in (remineralization), the structure is strengthened.
Caries disease exists when the bio-mineralization process is out of balance. Cariogenic bacteria generate acids when they metabolize fermentable carbohydrates. These acids dissolve tooth enamel and dentin, leading to cavities or carious lesions (Featherstone, 2018).
The common clinical response to cavities is to place a restoration, but merely restoring decayed teeth is not a solution to the problem, it is a Band-Aid. Most restorations eventually fail as a result of recurrent, or secondary caries (Mjör and Toffenetti, 2000).
Secondary caries refers to the process occurring at the interface between the tooth and the restoration, a vulnerable micro-gap infiltrated by bacteria, that increases as bacteria work their way in and cause a carious lesion.
This susceptible area is mostly untouched by the other technologies on the market today: fluoride-releasing materials have low antibacterial effect, which also fades out as the fluoride is depleted; chlorhexidine and other mouth washes are also short-term and kill the bacteria only in the outer plaque layers, not at the restoration-tooth interface, where it’s most needed. By contrast, Nobio’s technology is non-soluble (non-releasing) and incorporated into the restorative material, so it kills the bacteria right at the tooth-restoration interface, where the damage occurs, where it counts.
To make matters worse, the move from amalgam restorations to resin composite restorations increased the risk of secondary caries.
Amalgam is composed of heavy metals mercury, copper and silver, thus amalgam restorations are more effective at preventing secondary caries due to the metal corroding, killing the bacteria and sealing the tooth-restoration interface.
Although more aesthetically appealing, placing resin composite restorations is a technique-sensitive procedure that shows higher failure rates due to less stable adhesion to dentin and shrinkage during polymerization, forming micro-gaps at the restoration-tooth interface. Bacteria and nutrients infiltrate these gaps, what’s called “micro-leakage”, where they are protected and can thrive, causing recurring decay, or secondary caries. In addition, the composite material itself promotes plaque accumulation. As a result, studies show that composite restorations are twice as likely to fail as amalgam restorations (Rasines Alcaraz MG, et al., 2014).
Nobio’s technology consists of antimicrobial, filler particles that can be incorporated into resin-based materials and stay within the polymerized matrix after light-curing. The non-soluble antimicrobial effect is exerted only upon contact between the bacteria and the polymerized material, and is not dependent on release, so it doesn’t fade away or impact the oral flora. When integrated into restorative material, the antimicrobial particles will kill bacteria as they come in contact, protecting the tooth-restoration interface and possibly preventing secondary caries.
Nobio technology utilizes a high concentration of quaternary ammonium (QA) covalently bound to silica-based filler particles (Si). These QA+Si (or QASi) particles disrupt the membrane of bacteria, causing lysis, and cell death. Because this technology utilizes an electro-physical mechanism, it is less receptive to antimicrobial resistance, since there is no release of chemical to which the bacteria can adapt.
In a clinical study published in Proceedings of the National Academy of Sciences of the United States of America (PNAS), researchers measured the amount of living and dead bacteria on composites that were worn by 10 volunteers for four hours (Beyth, et al., 2010). Composites with 1% Nobio particles showed significantly less live bacteria compared to same composite material only without Nobio particles.
In contrast with other antimicrobials that have been integrated into composite materials (such as fluoride or silver, other ions, or antibacterial monomers), Nobio technology does not rely on an active agent being released from the composite to exert the antimicrobial affect, which also means it doesn’t affect the normal flora of the mouth. Instead, Nobio kills microbes that come in direct contact with the surface of the restoration, targeting the issue where it counts: at the tooth-restoration interface.
Any release-based antimicrobial approach will also result in the restoration losing mass over time, compromising its physical, mechanical, and optical properties. Because Nobio is a non-releasing technology, it preserves the integrity of the restoration and shouldn’t lose its effect over time.
After conducting extensive research on the effects of this antimicrobial technology in different dental materials, Nobio has incorporated the QASi particles into a new line of dental restorative materials, called Infinix.