SKELETAL CATEGORIES
The categorisation of the relationships of the jaws to each other, and to other elements of the craniofacial complex, is essential for correct diagnosis and consequently effective treatment. FIRST SKELETAL ORDER
This may be due to propria of the upper jaw (maxillary prognathism), mandibular retrognathism or a combination of both. THIRD GRADE
This may be caused by excessive growth of the lower jaw, small size of the upper jaw or a combination of both.