In order to properly describe an occlusion, we must not look at teeth in a vacuum, but as if we're starting at plaster models sitting on a table. We have to understand that teeth are one part of a larger system. Now, if one or both condyles have to displace in order for our teeth to come together in maximum intercuspation, or what we call MI.
What is MI?
Maximum intercuspation means we have an occlusion that's not stable. So in describing occlusions, we must consider the position and condition of the condyles as they relate to maximum intercuspation. The Dawson occlusal classification system does just this.
The Dawson Classification System Defined
In the Dawson system, a Type 1 occlusion is where the MI is in harmony with centric relation, or CR, meaning the joints are fully seated when the teeth come together. The jaw can close, bringing the teeth together, without any premature tooth contacts or interferences.
A Type 2 occlusion, on the other hand, is where the condyles have to displace to bring those teeth together to MI.
Type 3 is a condition where when we try to load the joints to try to verify CR, we run into tension or tenderness in the patient. Now, this condition in a Type 3 is deemed to be correctable, but remember, in order to look at the teeth in occlusion, the joints have to first be seated. So the focus here is to kind of slow down and correct that joint TMJ issue.
A Type 4 occlusion is where the joints have gone through progressive deformation or are actively going through that, and we have to get the yellow light here, stop until we can get those joints to an end stage.
Now, there are two more types, a Type 1A and a Type 2A. A stands for adaptation. This means the joints have gone through deformation but have reached an end stage where things are stable and we can now move on.
Learn more about the Dawson Classification System
The best place to truly understand the Dawson Classification System of Occlusion is through the Dawson Core Curriculum. Start your journey to predictability at the Functional Occlusion - From TMJ to Smile Design course.