ABSTRACT
This study was performed to assess the relationship of the morphology of the first cervical vertebra [atlas] with the direction of mandibular growth rotation. The sample included 200 lateral cephalometric radiographs [81 males and 119 females] of Iraqi18- 25 year old pretreatment orthodontic patients. Tracing was done for all of these cephalometric films, 3 linear measurements for the atlas and 6 angular measurements, these measurements were done by using special analyzing software program [Auto Cad] program. The results showed that atlas dorsal arch and atlas length had significant correlation with mandiular growth rotation, the higher the dorsal arch and the longer the atlas is the more the horizontal rotation of the mandible, It was found that the effect of the sum of posterior angles during mandibular growth rotation is due to the change in the gonial angle rather than the saddle and articular angles. It is concluded that the morphology of atlas can be regarded as a predictor for mandibular rotation