Dental caries, an infectious disease of bacterial aetiology, is a prevalent and costly disease in both developing and industrialised countries. It is an irreversible, multifactorial opportunistic infection. Treatment of dental caries continues to remain one of the most expensive treatments making it a major public health issue.
Researchers have focused on the development of a vaccine that would prevent this disease. Research efforts during the past 25 years have concentrated on determining the methods and mechanisms for inducing salivary immune responses to S. mutans in humans. Over 25 years, numerous research studies have delved into the complexities of dental caries, paving the way towards a potential vaccine breakthrough. Advancements in molecular biology and understanding of the mucosal immune system have led to a significant progress in developing of this vaccine.
Advancements in molecular biology have facilitated the cloning and functional characterisation of virulence factors of the mutans streptococci, including the cell-surface fibrillar proteins, which mediate adherence to the tooth surface, and the glucosyltransferase enzymes, which synthesise adhesive glucans and allow microbial accumulation on the teeth.
DENTISTRY- A complete timeline
Salivary Defense Against Dental Caries
Saliva plays a crucial role in protecting teeth by continuously bathing them in a solution rich in the immunoglobulin S-IgA, the main type of antibody found in this fluid. Therefore, the induction of a salivary S-IgA response against the mutans streptococci would provide a first line of defence against the colonisation of these bacteria on tooth surfaces.
Streptococcus mutans are the principle bacteria causing this disease. They start colonizing the oral cavity as early as 5 to 6 months of age. Specific secretory immunoglobulin A (IgA), present in the saliva, provides a specific immune defence against these cariogenic bacteria.
Current strategies for immunisation against dental caries are using these virulence factors as key antigens and incorporating them into novel mucosal vaccine systems and delivering them with or without adjuvants to mucosal IgA inductive sites. The most popular routes of mucosal immunisation are via the oral or also nasal route.
Dr. Rafiuddin Ahmed: “Father of modern dentistry” of India.
Promising Vaccines and the Path Forward
The mucosal immune system is functional in new-born infants, who develop salivary IgA antibodies. This is because they become colonised by oral micro-organisms. Mucosal immunisation strategies result in the induction of salivary IgA antibody responses. They pose fewer problems than parenteral injection of antigen.
Therefore, mucosal immunisation of infants prior to the appearance of their first teeth may be a well-tolerated and effective way to induce immunity against the colonisation of teeth by mutans streptococci and protection against subsequent dental caries.
In recent years some promising vaccines such as pGJA-P/VAX,LT derivatives/Pi36-512, KFD3-rPAc and DBR/GBR-CMV-nirB have been developed and tested in animals. A study reveals that the rats who were vaccinated also showed higher concentration of IgA in their saliva.
Bridging the gap between the lab and the pharmacy hinges on a collective effort. Researchers must foster collaborative studies, clinicians must conduct meticulous human trials. Also funders and public health officials must lend their support and expertise. They must pave the way for this treatment’s integration into mainstream pharmaceutical companies.
