Journal of Mashhad Dental School

Journal of Mashhad Dental School

The effect of four first premolar extraction on soft tissue profile in class I bimaxillary dentoalveolar protrusion patients

Document Type : original article

Authors
AbdolReza Jamilian 1
Abdolrahman Showkatbakhsh 2
Shima Safaeian 3
1 Assistant Professor, Dept of Orthodontics, School of Dentistry, Islamic Azad University, Tehran, Iran.
2 Associate Professor, Dept of Orthodontics, School of Dentistry, Shahid Beheshti University, Tehran, Iran
3 Dentist
10.22038/jmds.2004.1530
Abstract
Introduction:
The purpose of this study was to evaluate chephalometric changes of soft tissue profile after four first premolar extraction of upper and lower arch in class I bimaxillary dentoalveolar protrusion (B.D.P.) cases.
Materials and  Methods:
This investigation consisted of 20 female patients with B.D.P. The mean age of this group was 16±6 years with a range of 12 to 38 years. All of them treated by extraction of four first premolars with standard edgewise technique. Pre and post lateral cephalograms were traced and the cephalometric criteria were measured.
Results:
This study showed that upper and lower lip protrusion were decreased 2.7±2.9 (p<0/001), 2.8±2.8 (p<0/001) mm respectively. The angle between upper incisor to SN and lower incisor to mandibular plane decreased 10.3±5.8 and 8.3±5.2 respecticly. The angle between upper and lower incisor increased about 17.6±9.5. By using stepwise regression analysis the ratio of upper lip retraction to maxillary incisor retraction was 0.63:1 and the ratio of lower lip retraction to mandibular incisor retraction was 0.62:1.
Conclusion:
This study concluded that a strong correlation exists between retraction of anterior teeth and the position of lips.
Keywords
First premolar extraction
Bimaxillary dentoalveolar protrusion
Soft tissue profile
Journal of Mashhad Dental School
Volume 28, Issue 3,4
Autumn & Winter 2005
Autumn 2004
Pages 159-166

  • Receive Date 17 September 2013