Angle’s class III malocclusion is a commonly encountered orthodontic problem associated with disturbances of teeth occlusion. The condition is characterized by an elongated lower jaw and small or short upper. The disturbances in the size and position of the jaws leads to a forwardly placed lower jaw. Another variation of Angle’s class III malocclusion is pseudo class III malocclusion in which the habitual forward placement of mandible leads to illusion of a forwardly placed mandible. It is termed pseudo because the problem is not due to changes in bone structure.
Angle’s class III malocclusion is associated with skeletal problems in the development of jaw bone. It is commonly associated with a large prognathic mandible and short retrognathic maxilla or combination of both. The condition is associated with number of orthodontic problems such as edge-to-edge contact between the upper and lower teeth. The edge-to-edge contact causes attrition of the teeth and trauma from occlusion. It may also lead to an anterior cross bite characterized by forward placement of the lower teeth as compared to the upper teeth.
The upper dental arch is narrow and lower arch is larger and broader as compared to the upper arch. This size difference leads to posterior cross bites; a common finding associated with Angle’s class III malocclusion. The narrow upper arch leads to availability of space for the upper teeth leading to crowding of upper teeth. It may also be associated with an open bite or deep bite in vertically growing patients. Spacing between the teeth may be present in the mandibular arch. The chin is very prominent and gives a concave appearance to the face, when viewed from the side.
The skeletal Angle’s class III malocclusion is an inherited trait and has very strong genetic bases. The causes of pseudo malocclusion includes early loss of milk teeth leading to a habitual forward positioning of the mandible at an early age. Enlarged tonsils and repeated tonsillar infections also prompts the patient to place the mandible forwardly during swallowing or talking, leading to abnormal mandibular positioning. Pseudo class III malocclusion is most commonly caused by the presence of occlusal problems.
The treatment of Angle’s class III malocclusion differs in growing patients and the patient in which complete growth of the jaws have already taken place. In growing patients with the skeletal form of Angle’s class III maloclusion, orthopedic appliances such as face masks can be used to induce the growth of the maxilla in a forward direction. To treat mandibular prognathism face masks followed by chin caps and orthodontic appliances using myofunctional therapy can be used. Patients with pseudo malocclusion should be treated for the underlying cause.
In adult patients where growth of the jaws is already completed, camouflage by orthodontic therapy and surgical intervention are two available treatment forms. In mild to moderate cases, some teeth can be extracted to gain space in the dental arch followed by orthodontic movement of the other teeth in desired places, to regain occlusal harmony and aesthetic facial profile. Surgical options include orthognathic surgical procedure for advancement of the maxilla or surgical set back of the mandible.