If hair loss is a problem for adults, then tooth decay (scientific name caries) is a common headache problem for people of all ages.

According to statistics, the incidence of dental caries among adolescents in my country is over 50%, the incidence of dental caries among middle-aged people is over 80%, and among the elderly, the proportion is over 95%. If not treated in time, this common dental hard tissue bacterial disease will cause pulpitis and apical periodontitis, and even cause inflammation of the alveolar bone and jaw bone, which will seriously affect the health and life of the patient. Now, this disease may have encountered a “nemesis.”

At the American Chemical Society (ACS) Virtual Conference and Exhibition in the Fall 2020, researchers from the University of Illinois at Chicago reported a new type of cerium nanoparticle formulation that can prevent the formation of dental plaque and tooth decay within one day. At present, researchers have applied for a patent, and the preparation may be widely used in dental clinics in the future.

There are more than 700 kinds of bacteria in the human mouth. Among them, there are not only beneficial bacteria that help digest food or control other microorganisms, but also harmful bacteria including Streptococcus mutans. Such harmful bacteria can adhere to the teeth and gather to form a “biofilm”, consume sugars and produce acidic byproducts that corrode tooth enamel, thereby paving the way for “tooth decay”. 

Clinically, stannous fluoride, silver nitrate or silver diamine fluoride is often used to inhibit dental plaque and prevent further tooth decay. There are also studies that are trying to use nanoparticles made of zinc oxide, copper oxide, etc. to treat tooth decay. But the problem is that there are more than 20 teeth in the human oral cavity, and all of them are at risk of being eroded by bacteria. The repeated use of these drugs can kill beneficial cells and even cause the problem of drug resistance of harmful bacteria.

Therefore, researchers hope to find a way to protect the beneficial bacteria in the oral cavity and prevent tooth decay. They turned their attention to cerium oxide nanoparticles (molecular formula: CeO2). The particle is one of the important antibacterial materials and has the advantages of low toxicity to normal cells and the antibacterial mechanism based on reversible valence conversion. In 2019, researchers from Nankai University systematically explored the possible antibacterial mechanism of cerium oxide nanoparticles in Science China Materials.

According to the researchers’ report at the conference, they produced cerium oxide nanoparticles by dissolving cerium nitrate or ammonium sulfate in water, and studied the effect of the particles on the “biofilm” created by Streptococcus mutans. The results showed that although the cerium oxide nanoparticles could not remove the existing “biofilm”, they reduced its growth by 40%. Under similar conditions, the clinically known anti-cavity agent silver nitrate could not delay the “biofilm”. The development of “membrane”.

The main researcher of the project, Russell Pesavento of the University of Illinois at Chicago, said: “The advantage of this treatment method is that it appears to be less harmful to oral bacteria. Nanoparticles will only prevent microorganisms from adhering to the substance and forming a biofilm. And the particle’s toxicity and metabolic effects on human oral cells in a petri dish are less than silver nitrate in standard treatment.” 

Currently, the team is trying to use coatings to stabilize the nanoparticles at a neutral or weakly alkaline pH close to that of saliva. In the future, researchers will test the effect of this therapy on human cells in the lower digestive tract in a more complete oral microbial flora, so as to provide patients with a better overall sense of security.