Brief History of Occlusion

Occlusion has long been the subject of frustration and debate. It has also largely been moved forward in the understanding by removable prosthetics. Quite simply, it is in the removable prosthetic cases that full mouth rehabilitations are routinely performed. The overwhelming majority of dentistry that is tooth borne is done a tooth or two at a time with no long-term plan for optimizing the occlusal scheme.

shutterstock_142626751Going back just over 100 years there was the frustration of cross arch stability in complete denture cases. The idea to make flat plane occlusion where the teeth are hitting on both sides all the time was the first effort to stabilize and reset the dentures in function. Bilateral balanced occlusion is an important concept and it did help, however it isn’t the full story.

In the 1930s the concepts that are now referred to as gnathology were developed and essentially the importance of the bumps on the teeth were appreciated. This gives rise to several important things and some we are all familiar with such as the PK Thomas waxups. Incorporation of natural morphology into the occlusal scheme was beneficial – and combined with bilateral balanced occlusion, it allowed for much more comfort and much greater functional efficiency. However, it also did not answer the complete riddle of occlusion.

Some 20 years later the idea of that functional relationship being driven by not the bumps on the teeth, but rather the relationship of the jaw came about. The first definition of Centric Relation guided how we took bite records and although it isn’t necessarily a physiologic position, at least it allowed for repeatable record taking on these cases. The profession grabbed this concept and has been teaching it in all dental schools since. It is convenient for the repeatable records, but the cases did not predictably rehabilitate using the CR approach. In answer to that, we changed the definition of that one true CR spot. We changed it from the most superior to the posterior superior to anterior superior to almost 30 other one true spots and then created wiggle room with concepts like long centric. What was missing was that the patients we were treating weren’t simply skulls.

In the early 1970s pioneering “research” was done that combined technologies from outside dentistry to evaluate the muscles of mastication. It occurred to Dr. Barney Jankelson and John Radke that if we were to make our assessment and decisions with the muscles as a more central component that we might in fact have better success. Given that 90% of pain in the body is muscle in origin, this gives the dentist direct access and control to the source of pain! Utilizing technology like Ultra Low Frequency TENS (ULF-TENS) the muscles can be relaxed into their neutral state. In physiology we referred to this as the maximum action potential for the muscles, but in practice it simply is where they are happy. Starting the development of these cases from where the muscles are happy and combined with evaluation and appreciation of the joint relationship as well as creating ideal aesthetic tooth relationships is the next step in the evolution of occlusion.

What early occlusion focused on was micro-occlusion or tooth-to-tooth relationships alone. Then Centric Relation recognized that there was a larger side to this and looked at jaw relationships.” There is a larger side still; the incorporation of not just teeth, but also the bones as well as the muscles and various supporting soft tissues allows for the ideal and complete evaluation.

The Physiologic dentist pays careful consideration to the micro-occlusion but also is keenly aware of the macro-occlusion and the jaw-to-jaw relationship and posture is a critical and fundamental part of the diagnosis of the patient. The evolution from a narrow view of teeth only into a tooth and bone based decision was still falling very short of how the human works. The approach including muscles, or the Physiologic approach, is a significant leap forward in dental care and allows the dentist to eliminate an amazing amount of suffering that was previously untreatable, including such common issues as migraine and headaches.