1. It stimulates bruxing which leads to TMJ.
2. It tends to “collapse the occlusion” ( decreases the vertical dimension) which means that the Jaw on that side must close a bit further in order to get the teeth to touch. This pushes the ball joint of the jaw further into its socket causing injury to structures within the joint.
3. The tilted angles of the biting surfaces means that biting forces are no longer parallel with the long axis of the tooth (straight up and down the root of the tooth. This puts extra pressure on the bone which supports the tooth and tends to cause loss of the bone. This is a localized form of gum disease that over a period of years may ultimately lead to the loss of the tilted teeth.
4. The tilted and extruded position of the teeth place the contacts between these teeth and the adjacent teeth in unusual positions. The contact between the teeth is the place where decay is most likely to occur because it is a place where plaque tends to build up. Decay in unusual positions on the teeth is called “ectopic caries”, and it is generally quite difficult to repair without striking the nerve. When this happens, it becomes necessary either to extract the tooth or to perform a root canal procedure in order to avoid a toothache.
5. It makes it more difficult and expensive to replace the missing tooth later due to the poor position of the surrounding and opposing teeth.
Note that the loss of a back tooth, even if there are more teeth behind the space, does not always lead to the leaning and extrusion of the remaining teeth. If all of the teeth adjacent to the extracted tooth, as well as all teeth in the opposite arch make firm, stable contact with teeth in the opposing arch, and as long as at least half of the occlusal table (the top, chewing surface) is in stable contact with teeth in the opposing arch, then there is little likelihood of major tooth movement. This is especially true if the patient does not tend to have bruxing (grinding and clenching) habits.