Habitual occlusion corresponds to the habitually adopted tooth-closure position, which usually occurs at maximum frequent contact. In malocclusions, the habitual occlusion does not correspond to the physiologically intended occlusion. The so-called occlusion line helps to objectify bite malocclusions.
What is habitual occlusion?
Habitual occlusion corresponds to the habitually adopted tooth-closure position, which usually occurs at maximum frequent contact. In dentistry, occlusion corresponds to tooth-row closure. This is the position that the lower row of teeth occupies in relation to the upper row of teeth when the jaw is closed without constraint in the final bite position. The two main types of occlusion are static and dynamic occlusion. In the static form of occlusion, there is a union of the lower and upper rows of teeth to maximum possible multipoint contact and without movement of the mandible. Habitual occlusion is a subform of this type of occlusion. More precisely, it is a habitual occlusion of the teeth with maximum intercuspidation. The cusps and dimples in the upper and lower jaws interlock completely. The contact points of an occlusion lie on the so-called occlusal plane. Instead of being planar, this plane is sagittally and transversely curved or contorted. The medical terms of the Spee and Wilson curves describe this curvature.
Function and task
When the mouth is closed, the teeth of the lower jaw automatically come into contact with the dental ridges of the upper jaw in the process. The points of contact between the lower and upper dentition depend on the individual case. Habitual occlusion includes the tooth contacts that occur between the upper jaw and the lower jaw during the patient’s habitual bite. Habitual occlusion is adopted relatively unconsciously and cannot be changed in its tooth contacts via conscious processes. In most cases, the habitual occlusion corresponds to the intercuspidation position and thus the bite to maximum multiple contact of the dentition. A malocclusion is a habitually incorrect occlusion. The occlusal plane or masticatory plane corresponds to the spatial plane where the rows of teeth of the lower and upper jaw meet. It is constructed by the connecting lines between the incisal contact point of teeth 31 and 41 and the distal cusp of teeth 36 and 46. In healthy habitual occlusion, the occlusal plane passes through the lip closure line and is thus approximately parallel to the connecting line of both pupils and parallel to Camper’s plane. Orthodontics defines an occlusal plane for a habitually healthy occlusion as the connecting line between two constructed points. The point vPOcP is defined by bisecting the intermediate distance at the incisor overbite and thus corresponds to the midpoint at the line connecting the contact points of the lower maxillary central incisors. In this scheme, the hPOcP corresponds to the dital contact point of the molars in occlusion as the second constructed point. The occlusal plane provides metrological orientation for angulations of the lower and upper teeth and makes it possible to represent the angulation of the occlusal plane to various reference points. If the habitual occlusion deviates too far from the healthy occlusal plane, a malocclusion is present. Angulations and malfunctions of the dentition can be objectified thanks to this plane. The occlusal plane is the rough average of the clinical occlusion curve. This Spee’s curve corresponds to the natural course of the occlusal planes of individual teeth. The plane of habitual occlusion does not correspond to the ideal plane as a rule.
Diseases and complaints
In dysgnathia, the habitual occlusion is more or less different from the natural occlusal plane. These findings involve nonphysiologic development of the mandible or maxilla, which may result in displacement of the individual rows of teeth. In addition to pro- and retrogenia, pro- and retrognathia are also dysgnathia. Mandibular prognathism and mandibular retrognathism are characteristic examples of such malocclusions. Mandibular prognathism is genetically determined. The chin and lower lip protrude in this bite and a positive lip step is formed. The anterior teeth in the mandible are in front of the anterior teeth of the maxilla in habitual occlusion.Damage to the affected teeth and damage to the periodontium can be the result. Premature tooth loss is conceivable as a late consequence. In mandibular retrognathia, which is also genetically determined, a receding chin is accompanied by a protruding upper lip. Thus, a negative lip step is formed. The anterior teeth of the upper jaw come in front of the anterior teeth of the lower jaw during occlusion. Often, the lower jaw additionally bites into the palate. This type of malocclusion can also cause damage to the teeth or damage to the periodontium, which can lead to premature tooth loss in the long term. Often, dentition anomalies are assessed based on the habitual occlusion of the first lower molars to the first upper molars. This assessment takes place according to the Angle classification. Findings correspond to either Angle class I, II1, II2 or III. In Angle class I, the anterior cusp of the upper sixth molars intervenes between the cusps of the lower sixth molars. This occlusal position corresponds to the so-called neutral occlusion. A finding of Angle class II1 is present if the anterior cusp of the six-year upper molar occludes in front of the anterior cusp of the six-year lower molar and the upper anterior teeth are protruded. This habitual occlusion results primarily from prolonged thumb sucking during childhood. In findings of Angle class II2, the anterior cusp of the six-year upper molar occludes in front of the anterior cusp of the six-year lower molar and the upper anterior teeth are tilted palatally. Angle class III is present when the anterior cusp of the six-year premolar occludes posterior to the second cusp of the six-year premolar.
