This lack of normal tooth eruption can be due to a variety of factors such as failure of the developing tooth follicle to have the correct orientation, improper developmental timing of the tooth bud, or ankylosis of the developing adult tooth to the surrounding alveolar bone.
The wisdom teeth can just be extracted and removed, but other teeth that are impacted will have a more noticeable effect on the smile's appearance and also on a patient's occlusion and function.
This is especially true of the upper canines, which are the last of the front teeth to emerge and sometimes do become impacted. Usually, they are completely obscured by the bone and visible only in x-rays.