ABSTRACT
Since the introduction of minimum-preparation bridges there have been fluctuations in fashion as to the degree of tooth preparation that should be carried out. Initially very little preparation was undertaken, and then over the next few years various authors recommended more and more extensive preparation with finishing lines, seating grooves at right angles to the path of insertion and location grooves in the line of the path of insertion all being advocated. Some dentists even went as far as using operating microscopes and complicated paralleling devices.
