Researchers at the University of São Paulo found that these effects become stronger when the molecule is used together with fluoride and xylitol, rather than on its own.
An experimental artificial saliva developed as a mouthwash may help protect teeth in people with head and neck cancer. The product is made using the CANECPI-5 protein, which is extracted from sugarcane and altered under laboratory conditions.
For many cancer patients, radiation therapy delivered near the mouth damages salivary glands, sharply reducing saliva production. Because saliva is essential for limiting harmful bacteria and maintaining oral health, this loss can lead to serious dental problems.
Researchers at the Bauru School of Dentistry at the University of São Paulo (FOB-USP) in Brazil found that CANECPI-5 creates a protective “shield” over teeth. This layer helps preserve enamel by defending it against acids that weaken tooth structure, including acids present in fruit juices, alcoholic drinks, and even those that come from the stomach. The findings were published in the Journal of Dentistry.
The research was carried out during the doctoral studies of Natara Dias Gomes da Silva at FOB-USP. The project brought together scientists from several institutions, including the Federal University of São Carlos (UFSCar) in Brazil, the University of California in San Francisco in the United States, and Yonsei University College of Dentistry in South Korea.
The work is part of the Thematic Project “Modulation of acquired pellicle to control dental mineral loss: unveiling mechanisms to make therapies possible”, which is coordinated by Professor Marília Afonso Rabelo Buzalaf from FOB-USP.
Testing Artificial Saliva in the Laboratory
“We tested the mouthwash developed with CANECPI-5 by applying this solution to small pieces of animal teeth once a day for one minute. Based on these results, we’ll conduct further research so that we can think about applications of this product,” adds Silva, the first author of the article.
“This is the first product that uses the concept of acquired pellicle [a thin protective layer that quickly forms on the tooth surface] to treat xerostomia, which is the sensation of a dry mouth caused by a lack of saliva. We use substances that will reformulate the composition of the proteins that bind to the teeth,” explains Buzalaf.
“We’ve developed a process in which CANECPI-5 binds directly to tooth enamel, helping to make teeth more resistant to the action of acids produced by bacteria,” Silva points out.
Results reported in the study indicate that CANECPI-5 works best when used alongside fluoride and xylitol. Under these conditions, the artificial saliva spray led to a marked reduction in bacterial activity and tooth demineralization, a process in which teeth lose calcium and phosphate and become more prone to cavities.
The findings are particularly important because people receiving treatment for head and neck cancer currently lack a dedicated product designed to prevent or treat the severe tooth decay that often appears after radiation therapy.
“Artificial saliva improves the sensation of dry mouth and sores. This helps with discomfort and also combats bacteria. In some cases, the use of this type of product is only for a short time. In others, it’s permanent, because many individuals lose the ability to produce saliva,” adds Buzalaf.
A patent for the CANECPI-5 protein was filed several years ago. The researchers say the next major step is working with industry partners to scale up production so the artificial saliva can be manufactured for wider use.
“We’ve already tested the solution as a mouthwash, gel, and orodispersible film, which is a type of plastic that’s placed on the tongue and dissolves, releasing the protein. We’ve tested it in several vehicles and found that CANECPI-5 works very well in all of them. We’ll continue testing other technologies within the Thematic Project to use not only this protein, but others as well,” says Buzalaf.
Regarding the discovery of CANECPI-5
According to Flávio Henrique Silva, a professor in the Department of Genetics and Evolution at UFSCar, who worked on developing the CANECPI-5 protein, the work with cystatins (a family of proteins involved in various biological processes) is linked to research carried out under the Sugarcane Genome Project (SUCEST, FAPESP). His laboratory is part of that project.
“At that time, our group identified and produced, in a recombinant form in bacteria, the first cystatin from sugarcane. We named it CANECPI-1. We then identified and produced five other cane cystatins, including CANECPI-5, which had potent inhibitory activities against cysteine peptidases, which are its target enzymes. Throughout our work, we noticed that this protein bound strongly to smooth surfaces, such as the quartz cuvettes used in activity measurements. This led us to conduct tests in partnership with Professor Marília Buzalaf on the binding of the protein to tooth enamel.”
According to the researchers, the discovery that CANECPI-5 protects tooth enamel while also regulating the oral microbiota makes it a highly promising molecule for dentistry research.
“CANECPI-5 has also been used in the work of other colleagues in the field of dentistry, particularly involving periodontitis. We also have a collaborative project with a colleague from the Federal University of Uberlândia, using subcutaneous sponge implants in mice, which has shown that it’s capable of reducing inflammation and promoting angiogenesis [the formation of new blood vessels] and fibrinogenesis [the formation of fibrin, a protein essential for blood clotting], important processes in tissue repair, making it a candidate molecule for use in wound healing,” Silva points out.
Next steps
Within the Thematic Project, the researchers will continue trying to understand how CANECPI-5 interacts with other substances.
According to Buzalaf, one possible avenue is to study CANECPI-5 fused with a peptide derived from statherin, a protein found in saliva, to see if the new hybrid protein is more effective against the acids that weaken teeth when they come from the stomach. Another possible avenue is to try to understand how to combat periodontal disease.
“Another aspect of the Thematic Project is to associate CANECPI-5 with vitamin E because this vitamin acts as a carrier, bringing the protein into contact with the tooth. We imagine that this could facilitate the application of the product directly by the patient at home,” says the researcher.
Reference: “A novel artificial saliva enriched with CaneCPI-5 for irradiated head and neck cancer (HNC) patients: in vitro antimicrobial and anticaries effect” by Natara Dias Gomes Da Silva, Paulo Sérgio da Silva Santos, Flávio Henrique-Silva, Ana Carolina Magalhães, Marcos Roberto Chiaratti, Elbert de Josselin de Jong, Pamela K DenBesten and Marília Afonso Rabelo Buzalaf, 10 October 2025, Journal of Dentistry.
DOI: 10.1016/j.jdent.2025.106176
Funding: São Paulo Research Foundation
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