Orthodontic goniometry: detection and measurement of apical movement: Part 1

The possibility of apical expansion has been a matter of debate for a long time in orthodontics. Measure of expansion is easily obtained at the level of the crowns, but is coronal expansion a significant measure for apical expansion? This question received an answer as early as 1948 with the practical use of a method, "orthodontic goniometry" created by M. Chateau measuring the angular changes of incline of teeth (gonio = angle; metry = measurement).