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 taught me how to be a good tooth mechanic but left me without an understanding of how the teeth work physiologically together with the rest of the body. I felt like I knew the trees well, but I could not see the forest through them. 

Later, living with the primitive hilltribes of Northern Thailand, I noticed that their teeth looked very different from those of my dental patients back home. In chewing, their harmony and symmetry were remarkable. Their dental arches were obviously wider, their chewing was smoother, and they had none of the TMJ pathologies I had seen in my patients - even though many of them had worn their teeth down and therefore should have many functional and TMJ problems according to what I had been taught. Their relative TMJ health was not just due to lower stress levels, 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. In some pre-industrial skeletons, 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, narrow upper jawbones, and backwardly rotating lower jawbones commonly found in modern TMJ disorder patients. Their faces were noticeably more forwardly positioned, broader horizontally, shorter vertically, and more symmetrical than those of my patients.  Also their dental arches fit together over an area, making it impossible to find one centric bite position, which was a pathology according to what I had been taught.

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 in 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. Peter Begg showed in great detail how wear of teeth in Aborigines was designed to develop and maintain stable bites.

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 change in food content, mostly the increase in sugar and flour; but the narrowing and asymmetry of facial form was due the change in food consistency, specifically its loss of toughness.  Changes in the same direction can be produced in animals just by softening their food, while changes in the opposite direction can be produced in animals by hardening their food. 

I had already taken a teleological perspective to understanding health. I reasoned that, to understand how our bodies work now, we need to first understand how they were designed to work in the environment they evolved in. Only then can we see how the change that we have created in their functional environment has led to them working the way they do now.

I realized that, to understand how TMJ disorders arose, I had to study facial growth; because TMJ disorders are developmental disorders. People are not born with TMJ disorder, people grow into them. The TMJs are not even present at birth. TMJ disorders develop due to a strained facial growth pattern, mostly following the pubertal growth spurt, when average female facial growth patterns diverge from average male facial growth patterns in a more downward and backward direction. From looking at facial growth in tribes, I could see how our jaw systems were designed to grow and work differently. Then, looking at my patients, I could see how soft foods had caused their faces to grow more down and backward, - leading to TMJ disorders, obstructive sleep apnea, and forward head posture; and also how the bite table plays a central role in that 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.