Why are the lower anteriors last affected by the damage pattern of meth use?
We really do not know yet. The pattern is apparent but this issue has not been studied. It is hypothesized that because that area tends to stay dry when the patient is breathing through the mouth and has severe xerostomia. The bathing of the teeth with saliva that is very acidic is thought to create the decay pattern. It is also hypothesized that is why a cuspid can have severe decay on the entire tooth except the tip of the cusp. The decayed area is constantly being bathed with saliva that is extremely acidic and the tip is free from the exposure.
