Frequency of Medial Sigmoid Depression in Panoramic View of Orthodontic Patients Based on Facial Skeletal Classification

One of the normal landmarks in panoramic radiograph is in upper portion of mandibular ramus, which is termed medial sigmoid depression. Prevalence of this normal finding may be variable in different skeletal classification. Because this area is thin, it may also increase the potential for complications in orthognatic surgery if this area is involved.

Comparing the prevalence of medial sigmoid depression in panoramic view of orthodontic patient based on facial skeletal classification was objective point of this study.

In this study, 465 panoramic and lateral cephalometric views of patients (Including 236 cl.I, 141 cl.II and 88 cl.III patients) before orthodontic treatment were evaluated. Planmeca 2002 EC Proline Panoramic Machine provided all of radiographs. Angle classification was done by some orthodontists through study of cephalometry and consideration of their patients’ clinical status. Then panoramic radiographs were evaluated to determine present or absent of finding of medial sigmoid depression on RT and LT sides and categorized this finding to“ Marked” and “slight” criteria.

According to present study, prevalence of this depression was more common in skeletal cl.II (RT: %38.8, LT %39) and cl.III patients (RT: %23.9, LT: %38.6) in comparison with cl.I group (RT: %21.6, LT: %26.7) thus this finding has relationship with facial skeletal abnormalities. There was no correlation between this finding and side of involvement. No significant statistical difference was observed between the radiographic criteria of this depression in different skeletal classification.

High prevalence of medial sigmoid depression in patient with skeletal problem and more needs to orthodontic surgery in these groups were The most important results of consideration and attention to this area before mandibular osteotomies for prevention of any side effects.