ABSTRACT
Objectives: The aim of this study was to assess the effect of anterior teeth retraction on hyoid bone position in orthodontically treated adults with bimaxillary protrusion.
Materials and Methods: The retrospective data of this study were collected from pre and post treatment lateral cephalograms of twenty Class I bimaxillary protrusive adult female patients with mean age 21.5 years that required extraction of four first premolars and they were treated by preadjusted appliances with maximum anchorage. Lateral cephalograms were traced and analyzed on different linear parameters as (H-SN, H-FH, H-NL, H-Me and H-C3) and angular parameters as (ANB, U1/FH, L1/MP, SNH and MPH). Pretreatment and post treatment parameters variables were statistically analyzed and compared using paired t-test.
Results: The mean change of linear measurements (H-SN, H-FH, H-NL, H-C3 and H-Me) pre and post treatment showed statistically significant difference. The mean change of angular measurements (SNH and MPH) pre and post treatment showed statistically significant difference and (U1/SN and L1/MP) mean change showed statistically high significant difference while ANB showed non significant difference.
Conclusion: In bimaxillary protrusive adult patients the hyoid bone position is affected by retraction of incisors with extraction of four premolars.