The Development of the Dentition in Open Bites
An open bite can be defined as a lack of normal vertical contact between opposing teeth over a limited region or, as seldom occurs, over the total dental arch. The concept of open bite also covers the lack of vertical contact between the teeth and the gingiva, if further eruption should have resulted in contact between the teeth and the gingiva. This condition may occur in a severe Class 11/1 malocclusion with a large overjet in which the mandibular incisors have not fully erupted. Then the incisal edges of the mandibular incisors do not reach the palate. Some space remains in between.
An open bite is most frequently seen in the anterior region, mainly due to abnormal habits such as thumb or finger sucking. In these cases, the open bite is usually asymmetrically shaped. The position of the teeth and the deformation of the alveolar processes exhibit a configuration that represents more or less an impression, a negative of the thumb or fingers as they were placed in the mouth during sucking (Fig. 13-1).
Fig. 13-1 Simplified presentation of anterior open bites.
A,B Asymmetrical open bite caused by thumb or finger sucking. This form of open bite is frequently seen in the deciduous dentition. If the sucking habit is not terminated at an early age, the permanent incisors will attain a comparable open bite position after they have replaced their predecessors.
C,D Open bite due to an abnormal tongue position. This type of open bite is usually symmetrical in shape and can vary in size considerably. Vertical overlap of the opposing incisors may be present or absent.
Moreover, an open bite in the anterior region may also be caused by positioning of the anterior part of the tongue between the incisal edges of the mandibular incisors and the lingual surface of the maxillary incisors during normal, relaxed circumstances. When the tongue is placed between the incisal edges of the mandibular and maxillary incisors, the open bite may be so large that the incisors do not overlap vertically when the posterior teeth are brought into occlusion. In open bite subjects, the tongue is placed between the teeth to obtain an adequate seal of the anterior part of the mouth. Children with anterior open bites caused primarily by abnormal sucking habits also swallow with the tongue positioned in the open bite space to achieve an adequate enclosure. Generally, an open bite caused by a sucking habit will close spontaneously if the abnormal habit is eliminated, unless the abnormal tongue position is maintained.
An open bite can be encountered in all distinguishable types of jaw relations and occlusal conditions. It is frequently associated with a Class II/1 malocclusion. The size of the open bite can vary considerably and may range from a few millimeters to more than one centimeter. A small open bite is occasionally present in a Class II/1 malocclusion with the incisal edges of the mandibular incisors in close proximity to, but not in contact with, the palate. A large open bite can be encountered, for example, in a Cla/>