Arginine can modify plaque formation on teeth and protect against dental caries

Arginine can modify plaque formation on teeth and protect against dental caries

New human clinical study proves that the amino acid arginine can modify plaque formation on teeth and thus protect against dental caries.

An interesting human study by researchers at Aarhus University in Denmark compared dental plaque developed on custom-made dentures on both sides of the same participant's mouth. The team exposed both sides to sugar but only treated one with arginine to assess its benefits. Their results showed higher pH, altered biofilm structure and reduction in harmful bacteria, highlighting arginine's potential to prevent dental caries.

The fermentation of the sugar in our food by the numerous bacteria in our mouth creates acids that destroy our teeth and form tooth decay. These bacteria live in plaque-like communities called “dental biofilms.” Arginine, an amino acid that occurs naturally in our saliva, has been shown to be helpful in preventing tooth decay. Some beneficial bacteria have an arginine deiminase system (ADS) that helps break down arginine and form alkali that can neutralize the acids. The increased availability of arginine helps the proliferation of these beneficial bacteria while inhibiting the growth of acid-producing bacteria. Recent studies outside the human body also showed that arginine availability alters the composition of dental biofilms.

To further prove these findings in the human mouth, a team of dentists and researchers led by Post.doc. Yumi C. Del Rey and Professor Sebastian Schlafer from Aarhus University in Denmark conducted a clinical study and published their results inInternational Journal of Oral Science.

They recruited 12 participants with active tooth decay and prepared special prostheses that allow the accumulation of intact biofilms on both sides of the jaw. Participants were instructed to dip the dentures in a sugar solution for 5 minutes and then add distilled water (as a placebo) or arginine to each side for 30 minutes. This should be repeated three times daily, with arginine treatment on the same side each time. “The aim was to investigate the influence of arginine treatment on the acidity, bacterial species and carbohydrate matrix of biofilms from patients with active caries", explains Sebastian Schlafer, Professor at the Department of Dentistry and Oral Health. After 4 days, when the biofilm had developed, the dentures were removed for detailed analysis.

A special pH-sensitive dye called “C-SNARF-4” was used to analyze the acidity of the biofilms collected from different locations. Biofilms treated with arginine showed significantly higher pH (lower acidity) 10 and 35 minutes after sugar loading. “Our results showed differences in the acidity of the biofilms, with the biofilms treated with arginine being significantly better protected against acidification caused by sugar metabolismsays first author Yumi C. Del Rey.

Carbohydrate-binding proteins called lectins were then labeled with a fluorescent dye to stain two common carbohydrate components of biofilms: fucose and galactose. These components make up a large proportion of dental biofilms and can contribute to the formation of “acid pockets” within them. Arginine treatment saw an overall reduction in the amount of fucose-based carbohydrates, potentially making the biofilm less damaging. In addition, there was a change in the structure of the biofilm, with the galactose-containing carbohydrates decreasing towards the bottom and increasing towards the top.

Additionally, to determine which bacteria were present in the biofilm, they sequenced all of the bacterial genomes using a technique called “16S rRNA gene sequencing.” However, biofilms that were treated with arginine and placebo predominatedStreptococciAndVeillonellaArginine significantly reduced the Mitis/Oralis group of streptococci, which produce acid but are not strong alkali producers, and slightly increased streptococci with significant arginine metabolism, thereby improving pH. Overall, arginine made the biofilms less harmful by reducing their acidity, changing their carbohydrate structure and remodeling the microbiome within them.

Dental caries, which is widespread across all ages and regions, could be combated through strategies such as adding arginine to toothpastes or mouthwashes for people who are more susceptible to it. Arginine, an amino acid naturally produced in our bodies and found in dietary proteins, is harmless and may even have use in children.

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