Dental caries
Dental caries is the most prevalent chronic infectious disease worldwide, driven largely by Streptococcus mutans, which metabolizes dietary sugars into acid and builds the acidogenic, glucan-rich biofilm (dental plaque) that demineralizes enamel. Conventional measures (fluoride, chlorhexidine, mechanical debridement) are broadly antimicrobial and indiscriminate, wiping out commensal oral flora while failing to selectively eliminate the cariogenic pathogen, and antibiotic use raises resistance and dysbiosis concerns. Bacteriophages are attractive here because they are exquisitely strain-specific, self-amplify at the infection site, and can target S. mutans within plaque biofilms while sparing the rest of the oral microbiome. This precision makes phages (and their lytic enzymes) a logical "narrow-spectrum" tool for a disease defined by a single dominant pathogen embedded in biofilm.
How phages act here
Mechanism
S. mutans phages are highly serotype- and strain-specific: the prototypical lytic phage M102 infects serotype c strains, and adsorption depends on the rhamnose-glucose cell-wall polysaccharide, so loss or alteration of that receptor (or acquisition of CRISPR spacers, many of which are derived from phages M102 and APCM01) confers resistance—an important consideration arguing for multi-phage cocktails rather than single phages. Lytic phages such as φAPCM01 and SMHBZ8 not only kill planktonic S. mutans at very low multiplicity of infection but penetrate and collapse established biofilms, reducing metabolic activity and viable counts by several logs. Mechanistically, phages lyse cells via holin/endolysin lysis cassettes; the purified phage-derived lysin ClyR can hydrolyze the S. mutans cell wall directly, though the glucosyltransferase-made water-insoluble exopolysaccharide (EPS) matrix can adsorb and partly shield the enzyme, making EPS both a barrier and a target. Engineered and CRISPR-guided angles are under active exploration—isolation of temperate S. mutans phages (e.g., φKSM96) provides genetic scaffolds for building more efficient or sequence-targeted constructs, and sustained-release formulations are being developed to keep phages active in the oral cavity.
Where it stands
Current evidence
As of 2026 the evidence base is entirely preclinical—there are no registered human clinical trials of anti-S. mutans phage therapy. The field rests on in vitro and animal proof-of-concept. The most advanced result is from the Hebrew University of Jerusalem / Hadassah (Hazan, Beyth and colleagues): they isolated phage SMHBZ8 from human saliva (Viruses 2021) and then showed it prevented carious lesions both in vitro on dissected jaws and in vivo in a murine caries model, in suspension and in a sustained-release formulation (Antibiotics 2021). Earlier foundational work includes the M102 genome (2007) and isolation of φAPCM01 (Ireland, APC Microbiome/UCC, PLoS One 2015), which suppressed S. mutans biofilms in artificial saliva. Recent 2025 work characterizes phage resistance mechanisms (CRISPR spacers, rhamnose-glucose polysaccharide defects) and phage-lysin approaches (ClyR vs EPS, J Oral Microbiol 2025), and a 2026 review frames postbiotic-plus-phage synergy as a precision oral-microbiome strategy. Net stage: robust bench and small-animal data; human translation not yet begun.
Evidence confidence: medium
The data
Key studies & trials
- Wolfoviz-Zilberman A, Kraitman R, Hazan R, Friedman M, Houri-Haddad Y, Beyth N. Phage Targeting Streptococcus mutans In Vitro and In Vivo as a Caries-Preventive Modality. Antibiotics (Basel). 2021;10(8):1015. ↗
- Ben-Zaken H, Kraitman R, Coppenhagen-Glazer S, Khalifa L, Alkalay-Oren S, Gelman D, Ben-Gal G, Beyth N, Hazan R. Isolation and Characterization of Streptococcus mutans Phage as a Possible Treatment Agent for Caries. Viruses. 2021;13(5):825. ↗
- Dalmasso M, de Haas E, Neve H, Strain R, Cousin FJ, Stockdale SR, Ross RP, Hill C. Isolation of a Novel Phage with Activity against Streptococcus mutans Biofilms. PLoS One. 2015;10(9):e0138651. ↗
- van der Ploeg JR. Genome sequence of Streptococcus mutans bacteriophage M102. FEMS Microbiol Lett. 2007;275(1):130-138. ↗
Who is working on it
Programs & centers
The possibility
Picture a flavored phage rinse, lozenge, or slow-release varnish applied at a routine dental visit that quietly seeks out and dismantles only the cavity-causing S. mutans, leaving the protective oral microbiome intact—a "smart" alternative to the scorched-earth approach of broad antiseptics. Cocktails of complementary phages, or phage-derived lysins like ClyR paired with EPS-degrading enzymes, could outpace the bacterium's CRISPR and receptor-loss defenses and even reach into the biofilm matrix where conventional agents stall. If the strong rodent caries-prevention data translate, phage-based caries control could become one of the first everyday, microbiome-sparing antibacterials in dentistry.