Measuring 3-dimensional tooth movement with a 3-dimensional surface laser scanner

Introduction: Our aims in this study were to (1) develop a method of measuring 3-dimensional (3D) tooth movement using a 3D surface laser scanner, (2) test the accuracy of this method, and (3) compare the measurements with those from cephalometric radiographs. Methods: A method of superimposing pretreatment and posttreatment models on the palatal rugae was developed, and an experimental model was prepared to evaluate the accuracy and reliability of the laser scanner. Records were obtained from a prospective longitudinal randomized clinical trial evaluating anchorage loss with headgears and midpalatal osseointegrated implants as a source of anchorage in Chesterfield, United Kingdom. The pretreatment and posttreatment study models were analyzed by using a 3D laser scanner to measure the 3D tooth movement. Results: The laser scanner was accurate to 0.0235 mm for anteroposterior measurements and 0.0071 mm for buccolingual movements for every 0.5 mm of movement. The study model analysis showed that mesial molar movements were 1.38 mm on the right side and 1.11 mm on the left side for the implant group, and 2.24 mm on right side and 1.63 mm on left side for the headgear group, with no statistically significant difference between the groups. The results for vertical movement of molars showed extrusion on both sides in both groups but no statistically significant difference between the groups. In the transverse plane, the results were not statistically significantly different between the groups. The results from superimposition of lateral cephalograms were similar to those obtained from the scanner. Conclusions: The 3D laser scanner provides accurate and reliable measurements of tooth displacement and can be considered an alternative to cephalometric radiographs. (Am J Orthod Dentofacial Orthop 2009;135:480-5)