The Truth About Crossover Interferences
We talk about crossover in our occlusion courses. It is the lateral excursive position where the lower canine moves past the upper canine. If the anterior teeth are not set up correctly it can lead to posterior interferences and more breakdown of teeth in the chronic bruxer.
Look at the image of the models, this is a crossover interference. When the teeth are touching the anteriors are out of contact and all of the force on the left side is on that tooth.
Now look at the image of the tooth and see the wear facet on the distolingual and in the alloy.
This tooth had a deep crack under the filling and the tooth was sensitive to bite and release—classic cracked tooth syndrome. The patient also had a sore masseter muscle on the left side of her face.