Last updated: July 29, 2020
One of the most common mistakes I see in occlusal restorations is also the easiest mistake to observe. It is interference of the posterior teeth with the anterior guidance. A perfected occlusion allows the anterior teeth to contact in centric relation simultaneously, and with equal intensity with the posterior teeth. This harmony of contacts occurs with complete seating of the condyles at their most superior position, which is bone braced. This means that there is an ideal distribution of compressive contact starting at the TMJs, and continuing all the way through front tooth contact. This is the contact distribution that we want for centric relation.
When the jaw moves from centric relation, in a perfected occlusion only the anterior teeth contact. All posterior teeth distal to the cuspids should immediately separate. This is called “posterior disclusion”. Separation of the posterior teeth should occur, whether the jaw moves forward or left or right from centric relation.
The reason that posterior disclusion is such a desired effect is because the moment the posterior teeth separate, almost all of the elevator muscles shut off. This reduces the horizontal forces against the anterior teeth which are carrying all the forces in protrusive or lateral movements of the mandible. it also reduces the loading forces on the TMJ’s. But even more importantly, it is impossible to wear or overload the posterior teeth if they cannot rub.