Evaluation of space-closing techniques with the aid of laminagraphic cephalometrics

A method of taking cephalometric laminagraphic films of teeth in the buccal segments of the dental arches in order to evaluate cuspid-retraction mechanics is described. A submentovertical film is used to locate the position of the structures to be seen, and the machine is set accordingly. Seven different methods of cuspid retraction were studied, and comparisons were made of these methods with and without supplemental headgear. The methods included space closure by push- and pull-coil springs, elastics, various sizes of vertical spring loops, and direct headgear. A specialized tracing and superimposition technique was used because of the type of film produced. The four quadrants of each mouth were evaluated separately, and tooth movement was measured. A cuspid-retraction value and a cuspid-tipping number were recorded in each instance. The findings would indicate that with both sliding and closing loop mechanics, the higher-rate, higher-force springs produced greater forward movement of the posterior teeth than distal movement of the cuspids. Lower-rate springs and lower forces produced more cuspid movement than anchorage movement. The largest consistent difference in results was seen when anchorage was stabilized with the use of the headgear; the cuspids were retracted much farther into the extraction sites with this method. A greater amount of tipping occurred with loop appliances than with continuous arches. The greatest conservation of anchorage was recorded when the cuspids were retracted with direct headgear force.