Subdivisions (Angle), Forced Bites and Deviations in Transverse Dental Arch Relations
The contents of this chapter are not focused on developmental aspects but more on some consequences of certain deviations in the relationship between the two dental arches.
As has been indicated before, Angle supplemented his classification with subdivisions. In the Class II/1 subdivision (Fig. 14-1), a normal sagittal relation of the posterior teeth is present on one side and a Class II occlusion on the other. A corresponding situation exists in a Class III subdivision, in which a normal sagittal relation of the posterior teeth is present on one side and a Class III occlusion on the other (Fig. 14-2). According to Angle, a situation with a Class II occlusion on one side and a Class III on the other does not occur.1
Fig. 14-1 Schematic presentation of a Class II/1 subdivision.
A The posterior teeth show a normal transverse relation. In sagittal direction, a Class I molar occlusion exists on the right side, a Class II on the left.
B The overjet and overbite are too large; the midpoints of the two dental arches do not match.
Fig. 14-2 Schematic presentation of a Class III subdivision.
A A Class I molar occlusion on the right side, a Class III on the left.
B The midpoints of the two dental arches do not match; an anterior cross bite exists for the majority of the incisors and the left canines.
In a forced bite, the normal closing movement of the mandible cannot be continued in the intended direction of movement. The two dental arches make initial contact at one or more points. Subsequently, the mandible glides into a position in which more contact is reached between the mandibular and maxillary teeth. Forced bites can be distinguished in lateral and anterior ones and in a combination of both. In a lateral forced bite, first the posterior teeth usually attain contact when a normal closing movement is performed. Subsequently, the mandible glides laterally. A lateral forced bite is generally associated with a maxillary dental arch too narrow in comparison with the mandibular one. When maximal occlusal contact is established, a reversed transverse relation is present on one side. Also, the midpoints of the mandibular and maxillary dental arches do not match (Fig. 14-3).
Fig. 14-3 Schematic presentation of an example of a lateral forced bite. The mandibular teeth are drawn with continuing lines in the initial contact situation and with dotted lines in the habitual occlusion. The path of closure is indicated by an arrow.
A In the normal closing movement, initial contact is reached in the posterior regions between the cusp tips. Subsequently, the mandible glides to the right side, and more contact between the two dental arch/>