By the time most people are teenagers, they should have 28 adult teeth although some of these may still be coming through (erupting). The final four adult teeth (wisdom or third permanent molars) don't erupt until late teens - that is if they come through at all.

Early teens is when most braces are fitted if the teeth need to be straightened. For more information about braces, have a look in the treatments section on fixed and removable braces.