Anomalies of Dental Arches Relationships

By Vishaal on Thursday, December 6, 2007 with 0 comments

These anomalies can be evaluated at sagittal, transversal or vertical directions. At the sagittal plane, the lower dental arch can be positioned by three ways relative to the upper arch: normocclusion - 1st Angle’s class, distocclusion - 2nd Angle’s class, and mesiocclusion - 3rd Angle’s class.

Normocclusion is such relationship of dental arches when at the maximum inter-cuspidation, the mesiobuccal cusp of the first upper molar fits into the inter-cuspate groove of the first lower molar, and the cusp of the upper canine tooth fits between the lower canine tooth and the first premolar.

Distocclusion is characterized by the distal shift of the lower jaw. The first lower molar is shifted relative to the upper molar distally. This group of anomalies can be further divided into the first division - distocclusion is accompanied by protrusion of incisor teeth - and the second division - distocclusion is accompanied by retrusion of incisor teeth.

Mesiocclusion is characterized by the mesial shift of the lower jaw. At this position, the first lower molar is shifted mesially relative to the upper molar. The ventral position of the lower jaw is often accompanied by a reverse bite at the frontal section.

  • At the transversal plane, the buccal cusps of upper side teeth overlap those of lower teeth, at the maximum inter-cuspidation. A discrepancy between the width of upper and lower dental arches results in anomalies of the bite, designated as buccal nonocclusion, crossed bite, or palatine non-occlusion.
  • At the vertical plane, mutual position of jaws can be hindered by a deep or an open bite. The deep bite is such a bearing when upper incisor teeth overlap by more than two thirds of the labial surface of lower incisor teeth. The open bite is such an anomaly, where a vertical gap appears between groups of two or more adjacent teeth and their antagonists, at the maximum inter-cuspidation of the teeth. This anomaly may occur at the frontal or lateral sections of the teeth.

Category: Orthodontics Notes



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