Your Malocclusion Facts
Malocclusion is the condition in which there is a deviation of the normal teeth relations to each other in the same arch as well as to the teeth in the opposite arch. Knowing the ethiology of malocclusions is the key factor in preventive and therapeutic medical care. There are many classifications of malocclusions, but the most famous and used one is that of Dr. Angle. He gave three classes of malocclusions. His main theory is that the first permanent molars are the keys of occlusion and so the classes of malocclusions are related to discrepancies of molar relations.
I class: There is a neutral relation of the first permanent molars and other teeth have normal relations (canines and posterior teeth). But in the normal relation of the posterior teeth, the relation of the jaws doesn’t have to be in the I class. Morfology and function of orofacial muscle system in the I class is usually normal.
II class: Malocclusions of the II class are defined by the position and relation of the posterior teeth. The relation of the posterior teeth in occlusion is more distal than in the class I. Because of different morphological differences amongst front teeth, Angle has made two divisions of the II class malocclusions:
Malocclusions class II ,1. Division: Along with the distal relation of the posterior teeth, in this type of malocclusion there is a protrusion of the upper front teeth (front teeth are sticking out) and the lips are closed with difficulty. Because of this protrusion of the front teeth, upper lip covers the front teeth only partially and the lower lip is behind the front teeth.
Malocclusions class II, 2. Division: Lower posterior teeth are in the distal position to the upper teeth. In the classic cases of this malocclusion, central front incisives are retruded (pushed back) and lateral are protruded (pushed forward) and are slightly rotated. Deep bite is the main characteristic of this malocclusion as well.
III class: This malocclusion is also known as the prognathism or underbite. The lower jaw is in the mesial relation to the upper jaw and the lower canines are protruding and overlaping the front upper teeth (in classic cases). The lower jaw is usually more developed than the upper jaw, although this doesn’t always have to be the case.