Three-dimensional diagnosis & treatment planning: The use of 3D facial imaging and 3D cone beam CT in orthodontics and dentistry

July/August 2007 The goal of diagnosis and treatment planning in dentistry is to decide a course of treatment based on the evaluation of the initial condition of the patient’s anatomy from various types of imaging sources. These imaging sources (x-rays, photographs, etc) have traditionally been from twodimensional film-based systems and more recently from 2D digital imaging systems. Imaging in dentistry is used for developing various treatment plans, monitoring treatment response, and for evaluation of treatment outcomes. In orthodontics, imaging of the patient’s anatomy has traditionally been evaluated from two-dimensional (2D) imaging sources such as: 2D cephalometric X-rays (lateral, frontal, etc), panoramic and other x-rays, 2D facial and intra-oral photographs, etc. These 2D images and the resultant 2D tracings have then been compared to “standards” or “norms” created from data which differ by age, sex, race, etc. The limitations of 2D cephalometric projections have been known since its inception. Geometric errors of projection not only affect X-ray projections but also affect measurements made on 2D photographs and 2D video imaging. Evaluating the “Anatomic Truth” of our patient’s anatomy in 3D has traditionally been limited to evaluating the patient “live” in the chair and by the evaluations of dental study models (either plaster or 3D digital representations). New 3D technologies (3D facial scanning and 3D cone beam CBCT also known as Conebeam Volumetric Tomography (CVCT)) are just beginning to be introduced into the dental and orthodontic communities in order to evaluate the three-dimensional anatomic relationships of the patient’s true anatomy. The 4th dimension, which is time, consists of evaluating the three-dimensional relationships as they change over time. This could be in “real time” such as function, para-function, chewing, smiling, etc or “over a period of time” which could be days, weeks, months or years, such as aging, degenerative changes, traumatic changes, surgical changes, etc. It is essential to evaluate, analyze and use accurate imaging data that represents the “anatomic truth” of the patient’s anatomy. The American Dental Association defines evidence-based practice as an approach to oral health care that requires the judicious integration of systematic assessments of clinically relevant scientific evidence, relating to the patient’s oral and medical condition and history, with the dentist’s clinical expertise and the patient’s treatment needs and preferences. Evidence-based should be divided into two areas: 1) Evidence-based Diagnosis (EBD); and 2) Evidence-based Treatment (EBT). Evidence-based Diagnosis should be based on the best available data (i.e. imaging, diagnostic setups, tests, etc) for the time. Imaging should try and represent the “Anatomic Truth” so that diagnosis is based on accurate information. Diagnosis is the KEY to treatment planning, treatment monitoring and eventual actual treatment. Evidence-based Treatment should be based on the best available information of the time. There are many different types of “Treatment Philosophies” that are based on extensive clinical experience and scientific research. So EBT may vary between practitioners. What works well in one doctor’s hands may or may not work well for someone else. They may get to the same place as their goal, but they may get there differently. This seems to be the area of Evidence-based dental practice that creates the most confusion. “You don’t know what you don’t know and you don’t know what you can’t see”. digital | IMAGING