One of the easiest problems to spot is a build-up of plaque. Plaque is the soft, sticky layer of bacteria, which is constantly forming on the teeth.
Usually, it is invisible to the naked eye, but when a person is not brushing adequately, it can build up to where it appears to be a thick whitish coating on the teeth at the gum line. If not removed, it can lead to gum disease.
Another potential problem, which is easy to spot, is missing teeth. Many assume that if they are still able to eat, they are OK.
But very often, losing just one tooth can lead to the loss of support, and teeth begin to drift into the empty space, causing a change in the bite. It also forces the remaining teeth to carry an additional load, sometimes past their ability to adapt. In most cases, when even one tooth is lost, the remaining teeth suffer and are more likely to be lost as well.