The characteristic features of skeletal class III in Iraqi adult orthodontic patient

الملخص EN

Background : Skeletal class III malocclusion is one of the dentofacial anomalies which associated with deviation in the sagittal relationship of maxilla and mandible.

This study performed to determine the characteristic features of skeletal class III compared with skeletal class I.

Materials and methods : Skeletal class III sample included 100 pretreatment digital lateral cephalometric radiographs (18-29) years which selected on the basis of Beta angle [> 35°] and divided into five groups according to location of maxilla and mandible in relation to the anterior cranial base (SNA and SNB angles).

Another 45 radiographs were selected as control group (normal SNA, SNB angles, Beta angle 27°-35°).

Fourteen angular and eight linear measurements digitized and recorded using AutoCAD 2010 computer program.

Results and Conclusions : In comparison with skeletal class I, skeletal class III had: Shorter anterior cranial base length, more obtuse gonial angle, no significant difference in the articular angle and upper anterior facial height.

Labially proclined upper incisor and lingually retroclined lower incisor.

The prognathism of both jaws was formed 43% of the sample with the most horizontal growth pattern and protruded profile, the retrognathism of both jaws formed 20% with the most vertical growth pattern and retruded profile.

17% of the sample had normal positioned maxilla and protruded mandible and displayed horizontal growth pattern with protruded profile.

Pure retruded maxilla formed 12% of the sample and the least type was the combined maxillary retrognathism and mandibular prognathism (8%) ; both showed vertical growth pattern with protruded profile but extremely obvious in the latest one.