The accuracy of Visualized Treatment Objectives in bimaxillary protrusion patients

Bimaxillary protrusion is a condition characterized by protrusive and proclined upper and lower incisors and an increased procumbency of the lips. Visualized Treatment Objectives (VTO) are cephalometric tracings which predict average changes in skeletal dimensions, tooth positions and soft tissue responses that can be expected to occur during orthodontic treatment. Objectives: The aim of this project was to assess the accuracy of four VTO's in predicting the post-treatment positions of the incisors and the soft tissue response in a sample of patients with bimaxillary protrusion. Methods: The records of fifty orthodontically treated bimaxillary protrusion cases were randomly selected from the archives of orthodontic cases at the University of the Western Cape. The patients were aged between 12 and 16 years at the start of treatment, and maxillary and mandibular first premolars had been extracted. The Steyn (1979), Jacobson and Sadowsky (1980), Ricketts (1982) and Holdaway (1984) VTO's were constructed on cephalometric tracings of the patients and the data was analyzed statistically. Results: The results indicated that although most of the VTO's could predict the final position of the incisors to some extent, they were unable to predict the soft tissue response accurately. Of the four VTO's analysed the Steyn VTO came closest to correctly predicting these parameters. Conclusion: It was concluded that the soft tissue response was not accurately predicted by any of the VTO's used and that adjustments should be made in this regard when applying the VTO's to patients with bimaxillary protrusions.