Measuring Tooth Movements occurring during care using the Dahl Principle – A Retrospective Study.

This is a retrospective study where examiners will use previously obtained pre-operative and post-operative dental casts (dental casts obtained through alginate impressions) and other relevant information such as commencement and completion date of treatment using the Dahl principle.

Each cast will then be scanned with a 3D surface scanner to obtain 3D Standard Tessellation Language (STL) files (Identica T500, 2.0 MP cameras, blue LED, 3-axis automated scanning, MEDIT Corp, Seoul, South Korea; accuracy 7µm [ISO 12836]). The maxillary and mandibular STL files will then be superimposed using surface-matching software (Geo-magic Qualify 2013; 3D Systems Inc.) and tooth movements will be calculated in micrometres.

The aim of this project is to assess models of patients who were previously treated using the Dahl principle. The objectives include measuring the amount of tooth movement and duration to re-establish tooth contact. This project will also help develop an evidence based clinical guideline when using the Dahl principle for predictable results.