First-generation microtips were introduced in early 1990 by Cary Carr, made with stainless steel. Second- and third-generations improved the cutting efficiency by reducing the heat produced and the time required to prepare the retrocavity, by covering the tip with an aggressive coating: diamond or zirconium oxide. The more aggressive the tip, the more smear layer is produced.
After using an ultrasonic microtip, a 0.5 mm microplugger is used to condense the remaining gutta-percha and provide a flat-based retrocavity against which the retrofilling material can be condensed.
Microfractures are the main cause of long-term failure of apico-ectomy or re-apicoectomy. A final inspection of the retrocavity and the resected root at high magnification is necessary, to check that the microcavity walls and bottom are clean and dry, and whether there are accessory canals or microfractures not visible before the retrocavity preparation.