Stomach Ulcers and Dental Cavities
Just target the bacteria
Recently I learned about an effort to prevent dental cavities by using genetically modified bacteria to outcompete cavity-causing bacteria. This got me thinking: why has the idea of preventing cavities by targeting bacteria not been more developed already?
The current situation reminds me of the history of stomach ulcers. Before the 1980s, doctors recommended avoiding spicy foods and reducing stress to alleviate stomach ulcers. However, once Robin Warren and Barry Marshall proved ulcers were due to H. pylori infection,1 treatment with antibiotics to eliminate the bacteria became the standard of treatment.
Today, dentists recommend avoiding sugary foods and brushing your teeth to prevent cavities. But we know cavities are caused by bacteria (in particular Streptococcus mutans), so why not directly attack cavity-causing bacteria?
Some potential ideas:
Selectively targeted antibiotics
Vaccines (previously tried in the 1980s, not very successful because it’s difficult to get antibodies to penetrate biofilms, and also because S. mutans has several different strains with different antigenic profiles)
Outcompeting S. mutans with different bacteria (the current effort by Aaron Silverbook, which I think is promising)
Basically, what Aaron Silverbook is proposing to do is recreate a strain of S. mutans, termed BSC3-L1, that is deficient in lactic acid production. This was previously developed by a company called Oragenics, but they abandoned the effort (I think due to financial reasons). It seems Aaron’s team is mostly people from software backgrounds, so they would probably appreciate help from any talented microbiologists who happen to be reading this post.
In a famous case of self-experimentation, Marshall drank a culture of H. pylori and subsequently developed gastritis. For this work, Warren and Marshall earned the 2005 Nobel in Physiology/Medicine.
I've looked into the oral microbiome a bit. My impression is that there are bad bacteria and worse bacteria, and you kind of want to prevent anything from growing on your teeth.
That's mirrored the advice I got from my (Boston area, research adjacent) dentists on cavity prevention, which is mostly to use the newer zero-alcohol mouthwashes. The big developments recently in dentistry are new antimicrobials in toothpaste and mouthwash to keep the bacteria load in your mouth relatively low.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8037529/
There's also been some recent work in FISH microscopy of oral microbiome samples, which shows they've got a crazy level of spatial organization. It's really pretty, and might be pretty hard to disrupt with a single engineered bacteria. https://www.pnas.org/doi/10.1073/pnas.1522149113
Way back in the 1970s, I had a short piece published in Omni Magazine proposing "an ecological approach" to dental decay. I suggested that we identify people with perfect teeth, isolate and cultivate the strains of bacteria in their mouths, and then use those strains to inoculate the mouths of infants.
Afterward, I heard from several people that it is an established custom in some families for an adult with no cavities to rub a finger in their mouth and then rub it around on a baby's gums. Apparently, it works...sort of. The problem is that babies put so many things in their mouths that other bacteria can easily get added to the mix. Still, the founding culture gets a head start and can often fend off the interlopers.