Malocclusion is a displacement or incorrect connection between the teeth when they approach each other. The term was put forward by Edward Engle as a derivative of occlusion. Malocclusion (mal + occlusion = improper occlusion) refers to how opposing teeth meet.
Signs and Symptoms
Malocclusion is common, although it is usually not serious enough. Those with more severe malocclusion, which are present as part of craniofacial abnormalities, may require orthodontic and sometimes surgical treatment to correct the deformity. Correction can reduce the risk of tooth decay and relieve pressure on the mandibular joint. Orthodontic intervention is also used for aesthetic reasons.
Skeletal disharmonies often distort the shape of the patient's face. They seriously affect the aesthetic component of the face and can be combined with problems of chewing or speech. Most skeletal bites can only be treated with orthognathic surgery.
Classification
Depending on the sagittal ratio of teeth and jaws, the bite can be divided mainly into three types in accordance with the system of bite classes according to Engle, published at the end of the 19th century. There are other reasons, for example, crowding of the teeth, which does not directly fit into these types of malocclusion.
Many authors have tried to replace Angle's classification. This has led to many subtypes and new systems.
A deep bite (also known as a Type II bite) is a condition in which the upper teeth overlap the lower teeth, which can lead to trauma to hard and soft tissues, as well as to the appearance. Bottom type was found in 15-20% of the US population.
An open bite is a condition characterized by a complete absence of overlap and occlusion between the upper and lower incisors. In children, an open bite can be caused by prolonged suction of the finger. Patients often have speech and chewing disorders.
Angle classes, orthodontics
Edward Engle was the first to classify malocclusion. He based his systematization on the relative position of the first molar of the upper jaw. According to Engle, the mesio-buccal tip of the upper first molar should coincide with the buccal groove of the first molar of the lower jaw. All teeth should correspond to the occlusion line, which represents a smooth bend in the upper arch through the central fossa of the posterior teeth and the waist bone of the canines and incisors, and in the lower arch - a smooth bend through the sharp protrusions of the posterior teeth and the incisal edges of the front teeth. Any deviations from this led to types of malocclusion. There are also cases of a different class of malocclusion on the left and right sides. There are three classes of Engle in fangs and molars.
Class I
Neutroclusion. Here, the molar ratio is acceptable or as described for the first upper molar of the upper jaw, but other teeth have problems such as distance, crowding, excessive or insufficient teething, etc.
Class II
Distocclusion (retrognathism, excessive stream, excessive bite).
In this situation, it is observed that the mesio-buccal tip of the upper first molar does not coincide with the mesio-buccal groove of the lower first molar. Usually the mesio-buccal tubercle lies between the first mandibular molars and the second premolar. There are two subtypes:
- Section 1: molar relationships are the same as in class II, and the front teeth are protruded.
- Section 2: molar ratios are the same as in class II, but the central ones have a retrocline, and the posterior teeth are visible overlapping the central ones.
Class III
Mesiocclusion (prognathism, anterior cross bite, negative overload, lower bite). In this case, the upper molars are located not in the mesio-buccal groove, but in the back of it. The mesio-buccal tip of the first maxillary molar lies behind the mesio-buccal groove of the first molar of the lower jaw. The lower front teeth are more visible than the upper front teeth. In this case, the patient very often has a large lower jaw or short maxillary bone.
Alternative Systems Overview
The main disadvantage of the classification of malocclusions in accordance with the Engle class system is that it takes into account only a two-dimensional view along the axis in the sagittal plane during occlusion if the occlusion problems are three-dimensional. Other deviations in the spatial axes, functional deficiencies and other features associated with therapy are not recognized. Another disadvantage is the lack of theoretical justification for this descriptive class system. Among the weaknesses discussed is the fact that it does not take into account the development (etiology) of occlusion problems and does not pay attention to the proportions of teeth and face. Thus, numerous attempts were made to modify the Engle class system or completely replace it with a more efficient one. But she continues to lead mainly because of her simplicity and conciseness.
Known modifications of Engle's classification date back to Martin Dewey (1915) and Benno Lisher (1912, 1933). Alternative classifications were also proposed, among others, by Simon (1930, the first three-dimensional classification system), Jacob A. Salzmann (1950, with a classification system based on skeletal structures) and James L. Ackerman and William Profit (1969).