Introduction

 

BITES, FACIAL GROWTH, AND TMJ DISORDERS

The following manuscript grew out of a desire to better understand bites. Dental school had taught me guidelines for treating bites, but the rationales provided to justify those guidelines just didn't make sense.  Research on bites had been mostly concerned with tracking variables that seem unrelated to patient's overall health or even dental health.  My dental education had taught me how to be a good tooth mechanic, but it had not taught me how the teeth work together with the rest of the body.  I felt like dentistry had failed to see the forest through the trees.  

Later, living with the relatively primitive hilltribes of Northern Thailand, I noticed that their faces were very symmetrical, their chewing was smooth and efficient, and they showed few signs of clicking and other TMJ pathologies - even though they had worn their teeth down significantly and therefore should have many dental and TMJ problems according to what I had been taught. Their relative TMJ health was not just due to lower stress levels, because there were some people who lived under great stress for various reasons, and they exhibited the same healthy harmonious chewing systems.  

When I researched what I had seen, I learned that several dentists who traveled around the world in the first half of the twentieth century had made similar observations.  They documented the dramatic rise in cavities, gum disease, tooth crowding, and facial irregularities that occur whenever traditional cultures adopt a diet of refined foods, consisting largely of flour, sugar, and processed meats and fats.  Among these early dental researchers, Weston Price showed very clear examples of how, within one generation, the children of parents who had wide symmetrical faces and straight teeth developed narrow and irregular faces with crooked teeth after they moved into settlements and began eating processed food.  

While these early dental researchers had accurately observed many of the changes in the human jaw system that accompany modern civilization, they had no way to know which of the changes in the environment of the jaw system had caused each of these changes in the structures and health of the jaw system, and some of their work has been misinterpreted.  For example, Weston Price's work is now widely cited as evidence for the benefits of a diet that avoids grains (Paleo diet); yet now we know that, while the sugar and flour content in the modern diet is the cause of the dramatic rise in cavities and gum disease, it is the softness of our diet that has caused the rise in tooth crowding and facial irregularities.  Very similar tooth crowding and facial irregularities can be produced in animals just by softening their food by processing it, and changes in the opposite direction have been produced in animals by hardening their diet. Therefore, eating a Paleo diet that consists of softened and highly refined versions of the foods that our ancestors ate, like flours made from nuts rather than grains, may very well help some people improve their health for reasons we still do not understand, but it will do nothing to restore the natural straight teeth and well proportioned faces of our ancestors.

Like cavities, gum disease, tooth crowding, and facial irregularities; TMJ disorders are also primarily modern diseases of our jaw systems.  They arise all over the world within one generation whenever societies abandon their traditional life styles and adopt a diet of sweetened refined foods. Before the industrialization of food, there was no evidence of the types of TMJ disorders that are common in modern societies today. In the thousands of intact human skulls in museums as well as in the few tribes still living traditional life styles, we can see evidence of arthritic degeneration of the TMJs associated with injuries and extreme tooth wear, but we see no evidence of the dislocated disks, strained and unstable dental occlusions, or the narrow upper jawbones, asymmetrical features, and backwardly rotating lower jawbone growth commonly found in modern TMJ disorder patients.   

TMJ disorders in modern humans are also developmental disorders.  They are not found in children. The symptoms generally start to appear just after puberty, and they become increasingly prevalent during the teenage years.  The problem develops with age, because the ultimate cause is a strained facial growth pattern that appears mostly in females after the pubertal growth spurt and continues well into adulthood.  

To understand how the recent softening of our diet has changed modern human facial growth and thereby caused TMJ disorders to become prevalent requires seeing the role of the bite table in the context of evolution.  Chapter 1 describes how our jaw system evolved.  Chapter 2 describes the functional harmony it attained in our ancestors.  Chapter 3 describes how it grew and developed to attain such a functional harmony.  Chapter 4 describes how it grows and develops differently now as a result of our soft diet.  Chapter 5 describes some of the effects of this change.