Figure 1.
Specimen preparation: (a) The crowns of 24 lower premolars were removed and post cavities were prepared. (b) The external surfaces were built up with resin composite. The cavity was dried with paper points prior to the application of adhesives. The application procedure for each system followed the manufacturer’s instructions. For resin core construction, light-curing was carried out according to each manufacturer’s specified duration. (c) The specimens were sectioned into 8 slabs (4 coronal, 4 apical). (d) The slabs were sectioned into 0.6~0.6 mm2 stick-shaped beams. µTBS was performed.