Digital orthodontics: Limitations and advantages.

Objective: Recently many orthodontists have shifted to digital orthodontics. Our aim is to define the steps to this process and indicate its advantages and limitations. Methods: The first step is to produce a 3D image from the dentition. Desktop scanners produce the most accurate results. There are still discrepancies in cases with crowding more than 4mm and in reliability of arch dimension calculations. The next step is separating the teeth with their correct dimension to align them on the therapeutic arch form. The selection of the arch for the patient is another important decision and many mathematical equations have been introduced that 6th degree polynomials seem to be one of the best. In growing patients predicting amount of changes is more difficult because a factor of growth changes is added to other factors effecting treatment outcomes. Results: The capacity of predicting the final arch form is still at most 60%, and this indicates that fitting an arch wire to selected points on the teeth even based on mathematical equations is not enough for predicting the final arch form of patient after treatment. In order to plan the treatment in clear aligners there is a need to superimpose the initial and predicted results on each other. The methods for superimposition are either on anatomic landmarks or by surface matching. Four areas have been used for maxillary superimposition. Alveolar bone, rugae region, a major region of the palate and on or adjacent to incisive papilla. Conclusion: The capacity of predicting the final arch form is still at most 60%, it seems that there is still need for further research on the best method to use for superimposition.