Evaluation of arch forms depending on the angle classification

It is generally accepted that each individual has his or her own dental arch form. However, during orthodontic treatment, industrially preshaped archwires are widely used. The resulting use of the same arch form for all malocclusions may compromise occlusal stability after orthodontic treatment.

To determine the average dental arch form of a non-consulting Moroccan population depending on the Angle classification, after digitization of plaster models of the dental arches.

A sample of 50 dental students aged between 21 and 27 was selected. After digitization of the plaster models to produce a cloud of points, the barycentric method was applied to this representation, enabling all the arch shapes of each series to be superimposed with Photoshop CS 5 software (layer mode) and the average curves for each Angle class to be thereby determined.

The average maxillary and mandibular arch forms were defined for each class: Class I: a normal maxillary form and an ovoid mandibular form; Class II: a tapered maxillary form and a narrow tapered mandibular form; Class III: narrow tapered forms for both upper and lower arches. Globally speaking, in this sample an ovoid mandibular arch form and a normal maxillary arch form are the dominant shapes.

The studied population exhibited specific arch form features. This study could serve as the basis for the choice and use of preformed archwires better-adapted to the needs of our patients.