Superimposition Requirements

Monitoring treatment progress and outcomes is critical to patient care. The purpose of superimpositions is to aid the orthodontist in determining the skeletal and dental changes that occur over time. Three superimpositions are required by the American Board of Orthodontics: Cranial Base, Maxillary, and Mandibular Superimpositions. These superimpositions must be performed using the structural method,1 which is based on the use of stable structures described in Melsen's research of cranial base growth,2 Bjork and Skieler's implant research,1,3as well as Enlow's investigation of remodeling.4 The structural method has been shown to be reliable and valid.5,6,7

 

Video Demonstrations of Structural Method for Superimposition

Narrated by Peter Buschang, PhD  Released March, 2014

Cranial Base Superimposition

Mandibular Superimposition

Maxillary Superimposition

 

Superimposition Requirements

1. Conform to requirements discussed under Tracings and Superimpositions Requirements

2. Register the superimpositions using the true radiographic anatomical outlines in accordance with the video demonstrations above.

3. When there is an Interim set of records, separate superimpositions of A and B tracings, A and A1 tracings, and A1 and B tracings are required.

4. Arrange the three superimpositions on a single page as demonstrated in the following exhibit:   Example of Superimpositions

5. When the examinee indicates that pre and post-treatment lateral cephalograms were not taken on the same machine:

  • Cephalometric tracings are still required, but superimposition(s) are not required.
  • The examinee must explain the reason for the absence of superimposition(s).
  • The examinee must be able to explain the changes that occurred during the treatment of their patient.
  • The examinee will be sent a board case(s) with pre- and post-treatment cephalograms which require tracings and superimpositions to be presented with their case reports.
  • Notate this with a checkmark in the appropriate box of the Written Case Report, Results Achieved section.
  • You are representing that the lateral cephalograms were not exposed on the same machine and disproportionate magnification occurred. In this situation, superimpositions are preferred but are not required.
  • You are responsible for knowing and explaining the superimposition requirements and the changes that occurred as a result of treatment and growth.
  • ABO Policy Statement Regarding Lateral Cephalometric Radiographs and Superimposition of Tracings 

 

Bjork A, Skieller V. Normal and abnormal growth of the mandible: A synthesis of longitudinal cephalometric implant studies over a period of 25 years. Eur J Orthod 1983;5:1-46. 
2 Melsen B. The cranial base: The postnatal development of the cranial base studied histologically on human autopsy material. Acta Odontol Scand Suppl 1974;32(62):1-126. 
Bjork A, Skieller V. Growth of the maxilla in three dimensions as revealed radiographically by the implant method. Br J Orthod 1977;4:53-64. 
4 Enlow DH, Harris DB. A study of the postnatal growth of the human mandible. Amer J Orthod 1964;50:25-50.
5 Buschang PH, LaPalme L, Tanquay R, Demirjian A. The technical reliability of superimposition on cranial base and mandibular structures. Eur J Orthod 1986;8:152-156. 
6 Doppel D, Damon W, Joondeph D, Little R. An investigation of maxillary superimposition techniques using metallic implants. Amer J. Orthod Dentofac Orthop 1994;105:161-168. 
7 Nielsen IL. Maxillary superimposition: A comparison of three methods for cephalometric evaluation of growth and treatment change. Amer J. Orthod Dentofac Orthop 1989;95:422-431.