Why are our teeth crooked?
April 20, 2020
Spend any time in a pediatric clinic or school setting and you will notice two things: crooked teeth and cavities. Why is this the norm? A new article in this month's Scientific American tackles this question. Peter Ungar, a dental anthropologist and evolutionary biologist, thinks that the issues of today are not the issues of the past. Our ancestral kin did not have similar issues with crowding and cavities. If they did not and we do, why?
The simple answer is that the change of food types from harder more fibrous foods to softer and sugar laden foods has brought about this dysfunctional change that only benefits one group, the dental community, that thankfully enters mouths routinely to heal what we have broken. But, the simple answer does not suffice. What is really happening?
Let us look at the tooth. See Image. It is a bony structure covered with a special calcium phosphate material named enamel in a prismatic tubular formation for max strength. This hardened enamel provides our tooth the ability to chew thousands of times a week without breaking down or having micro fractures despite the pounding and aggressive activity that they are put through. Interestingly enough, the scales of a shark are made from the same material and use the same genetic codes as our teeth as their blueprint for production. Our teeth are naturally opposed top and bottom within close proximity to facilitate safe and aggressive chewing to maximize the acquisition of calories for our brains massive energy needs.
Human teeth are a classic combination of tearing and grinding teeth that are seen in omnivore type animals with the expressed evolutionary choice to consume animal products that are loaded with energy for maximal growth.
"The evolutionary history of our teeth explains not only why they are so strong but also why they fall short today. The basic idea is that structures evolve to operate within a specific range of environmental conditions, which in the case of our teeth include the chemicals and bacteria in the mouth, as well as strain and abrasion. It follows that changes to the oral environment can catch our teeth off guard. Such is the case with our modern diets, which are unlike any in the history of life on our planet. The resulting mismatch between our biology and our behavior explains the dental caries (cavities), impacted wisdom teeth and other orthodontic problems that afflict us." (Ungar 2020)
According to Ungar, 90% of Americans have dental caries, or 294,000,000 people. Yikes. However, as an anthropologist studying teeth, he has discerned that this is a modern issue. One of the main reasons behind this problem happens to be my favorite topic, the microbiome or in this case the oral microbiome. He wrote this section so well that I will present it in it's entirety here.
"To understand why the teeth of modern-day humans are so prone to decay, we need to consider the natural oral environment. The healthy mouth is teeming with life, populated by billions of microbes representing up to 700 different species of bacteria alone. Most are beneficial. They fight disease, help with digestion and regulate various bodily functions. Other bacteria are harmful to teeth, such as mutans streptococci and Lactobacillus. They attack enamel with lactic acid produced during their metabolism. But concentrations of these bacteria are usually too low to cause permanent damage. Their numbers are kept in check by their commensal cousins, the mitis and sanguinis streptococcal groups. These bacteria produce alkalis (chemicals that raise pH), as well as antimicrobial proteins that inhibit the growth of harmful species. Saliva buffers the teeth against acid attack and bathes them in calcium and phosphate to remineralize their surface. The balance between demineralization and remineralization has held for hundreds of millions of years, and both beneficial and harmful bacteria are found in oral microbiomes across the mammalian order. "
"Caries results when... diets rich in carbohydrates feed acid-producing bacteria, lowering oral pH. Mutans streptococci and other harmful species thrive in the acidic environment they produce, and they begin to swamp beneficial bacteria, further reducing pH. This chain of events leads to what clinical researchers call dysbiosis, a shift in balance wherein a few harmful species outcompete those that normally dominate the oral microbiome. Saliva cannot remineralize enamel fast enough to keep up, and the equilibrium between loss and repair is shot. Sucrose-common sugar-is especially problematic. Harmful bacteria use it to form a thick, sticky plaque that binds them to teeth and to store energy that feeds them between meals, meaning the teeth suffer longer exposure to acid attack." (Ungar 2020)
The largest change in tooth decay from baseline norms came when humans began refining sugar and carbohydrates in vast quantities. This change reduced the volume of fibrous foods that humans ate which were abrasive cleaners of the teeth while simultaneously increasing the fuel source for the wrong bacteria that produced acid instead of alkali. Once the acid has burned through the enamel, the dentin and the pulp are now at risk for damage. The enamel cannot be remade making the tooth forever at risk unless modern dentistry comes to the rescue. This is a repeated pattern for the entire alimentary canal. Refined high calorie, low micronutrient foods coupled with toxins ingested via pesticides and agrichemicals are poisoning our alimentary microbiome from mouth to rectum causing damage and inflammation throughout to our health detriment.
Read Chapter 3 of Nourish your Tribe for a deeper dive into this topic.
I have had many discussions about oral health with Dr. Luis Crespo in Cornelius, NC and the conclusion is always the same, our infant/toddler diet and a lack of proper breast-feeding activity and technique are driving much of the oral problems that includes caries, malocclusion and oral motor dysfunction. Reversing these maladies requires early intervention with proper breastfeeding, proper whole foods based eating patterns and avoidance of refined carbohydrates. See Dr. Crespo Article from 2018.
Over the past decade of writing, one truth keeps screaming through the research. Nutrition is the major route to health and vitality while the Standard American Diet is the opposing force of disease and morbidity. In this article, we see yet again how poor quality food disrupts the natural physiology of our oral cavity.
Time plus sugar equals tooth decay - very simple reality,
Scientific American Ungar Article
Nourish Your Tribe
Farooq Electronics Article