Janes writes:

Dear twim team,

Regarding the last episode #217 (you were talking about the benefits of water fluoridation at the end): I do not know to what concentration levels the authorities add Fluoride to the drinking water in America. The so called dmft (decayed, missing, filled teeth) index if I recall it correctly is not much better in the us than over here in central Europe where we do not add fluoride to the tap-water which is a good thing I strongly believe. I surely do understand the chemistry behind making the Enamel/ hydroxylapatite more resistant to lower pH levels by swapping the hydroxyl group with a fluoride atom. However, forbidding the use of high fructose corn sirup and all industrial produced sucrose would have a much better effect on dental health than  fluoridation of the tap-water.  So what is more acceptable ? Would a tax on sugar be a good compromise to keep the stephens curve at dental friendly levels ? It would be considered unethical and against the law here to add anything to the tap water however beneficial it might be to some people who do not take care of their alimentation, which is the ultimate cause of making oral bacteria “sweat” acids. Streptococcus mutans is not always found in carious lesions. Processed food and sucrose/dextrose everywhere in amounts not possible before the advent of industrialised food-production cause an ecological/environmental shift in the bacterial composition in the oral cavity/microbiome as explained in the last episode. When these bacteria attach to the teeth and form a biofilm they will be starting to produce acids if one continues to eat a lot of industrial foods/concentrated sucrose. Strep mutans is not required for this process. A good read here for every dental student is Marsh / oral microbiology (https://books.google.de/books/about/Oral_Microbiology_E_Book.html?id=EZeHhpjhDSgC&redir_esc=y), Caries Management – Science and Clinical Practice / Meyer Hückel (https://books.google.de/books?id=B_GM4W3mO8IC&hl=de ) and Caries Excavation: Evolution of Treating Cavitated Carious Lesions https://www.karger.com/Book/Home/277210 . People from areas where you do not find a lot of processed food/sugar tend to have excellent teeth until they arrive here. The dentist Weston Price documented in his book nutrition & physical degeneration that we just need to brush our teeth because we eat what we eat in the western world. Maybe there is a chance to get some experts on the show regarding this topic. Tooth decay is one of the most common health problems and if the ca 1000 different bacterial species in our mouth enter the pulp & thus our blood-system you will see patients coming up with heart problems. There certainly has been a paradigm shift in the understanding of dental caries (or ultimately, which bacteria sweat acids and why), but I do not follow the Journal of dental research so closely anymore. One thing which is puzzling is that secondary carious below fillings is possible as it must be because of enough substrate (enough sucrose) finding its way below the filling/microleakage. As described in Schwendickes book not all of the bacteria is removed anymore when excavating close to the pulp in order to preserve it. Seal is the new deal and studies how this plays out are ongoing. Another interesting topic for a podcast would be the known relations between tooth decay and heart disease https://www.nature.com/articles/s41598-019-47029-3

Wish you all the best and thank you for your great work you do. I always love learning this way. 

See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547570/ recommend levels 0.7 milligrams/liter (mg/L) July 2015

From Importance of community water fluoridation. Community water fluoridation is a major factor responsible for the decline in prevalence (occurrence) and severity of dental caries (tooth decay) during the second half of the 20th century.  Achievements in public health, 1900–1999: fluoridation of drink- ing water to prevent dental caries. MMWR Morb Mortal Wkly Rep 1999;48(41):933-40.

Justin writes:

Dentists extract new fee from patients to keep up with rising COVID-19 costs


pretty sure TWIM said this a month ago