Introduction

 

The following manuscript grew out of a desire to understand bites. As a philosophy major, I always tried to get to the bottom of things. In dental school,  the bite seemed fundamental to understanding how the teeth work, but explanations of how bites work didn't make sense, and the rationales provided to justify the reverential attitude about preserving every centric bite contact with a level of care that approached worship just seemed contrived. Studies of bites had been mostly concerned with tracking variables that seem unrelated to patient's overall health or even the health of the jaw system. My dental education had left me without an understanding of how the teeth work physiologically together with the rest of the body. I felt like couldn't see the forest through the trees.

Later, after working in a refugee camp and then living with the primitive hilltribes of Northern Thailand, I noticed that their teeth looked very different from those of my dental patients back home. Their jaw systems showed a functional harmony that I had not seen before. Their dental arches were much wider, their chewing was smoother and more symmetrical, and their TMJs did not click or hurt, - even though many of them had very worn teeth and therefore should have many dental and TMJ problems, according to what I had been taught in dental school. Their chewing seemed easy and enjoyable, in contrast to some of my patients back home, who seemed to chew slowly and with more effort, even looking uncomfortable at times. Also, the relative jaw system health in these tribal people was not just due to the lower stress levels of a simpler life, because the same healthy harmonious chewing systems were also present among the few of them who lived under great stress due to real physical dangers.  

To research what I had seen, I went to museums to study their craniofacial structures. The functional harmony that I observed in their chewing behavior could be seen in the way their craniofacial skeletons. In some, both dentitions and TMJs were extremely worn down; and, in a few, they were worn out; but there was no evidence of the unstable bites, irregular condyle shapes, narrow upper jawbones, and backwardly rotating lower jawbones common in people with clinical and subclinical TMJ disorders. Their facial bones were more forwardly positioned, broader horizontally, shorter vertically, and more symmetrical than those I was used to seeing back home.  Also their dental arches fit perfectly together over a large area rather than in only one well defined bite position.

I learned that several dentists who traveled around the world in the first half of the twentieth century to study the teeth and jaws of tribal people had all noted the same change of facial shape in parallel with the dramatic rise in cavities, gum disease, and tooth crowding that occurred whenever they gave up their traditional diets and adopted a diet of processed foods. Weston Price and others showed very clear examples of how, within one generation, the children of parents who had wide symmetrical faces and healthy straight teeth developed cavities, gum disease, crooked teeth, and narrow asymmetrical faces after they moved into settlements and began eating government rations of flour, sugar, and canned meats. 

Unfortunately, these early dental researchers had no way to know which of the changes in diet had caused each of these changes in the jaw system, and some of their work has been misinterpreted. For example, the rise in cavities and gum disease was due to the increase in sugar and flour; but the narrowing and asymmetry of facial form was due the softening of the food. Changes in the same direction can be produced in animals just by softening their food. The decreased chewing forces have caused the change in our facial growth, which has led to TMJ disorders, obstructive sleep apnea, and forward head posture.

The ETIOLOGY chapters tell that fascinating story. 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 that functional harmony. Chapter 4 describes how it grows and develops differently now. Chapter 5 describes some of the effects of those changes.