Abstract This study investigated the effect of preparation curvature and leucite-reinforced glass-ceramic restorations on the fatigue behavior and stress distribution of the bonded ceramic restorations. Finite element analysis (FEA) was performed for the three experimental groups: flat preparation (Flat), preparation with a 2 mm radius of curvature (Curv1), and preparation with a 10 mm radius of curvature (Curv2). The Maximum Principal Stress (MPS) criterion was used to assess stress distribution. Then, resin composite discs were prepared to simulate the different curvatures (Flat, Curv1, and Curv2; n = 10), and leucite-reinforced glass-ceramic restorations with matching curvatures were bonded to them. Fatigue behavior was assessed using an accelerated fatigue test (10,000 cycles/step; 25 N increments; 20 Hz; initial load = 200 N). Fatigue failure load (FFL) and number of cycles for failure (CFF) were analyzed using Kaplan Meier analysis with post-hoc Mantel-Cox (log-rank) test (α = 0.05). The Flat group exhibited the lowest stress concentration (MPS = 4.5 MPa) on FEA, followed by Curv1 (MPS = 17.6 MPa) and Curv2 (MPS = 24 MPa). The Flat group also demonstrated the highest fatigue results (FFL = 632.50 MPa; CFF = 180,666 cycles). No statistically significant difference was found between Curv1 and Curv2 for fatigue values (FFL and CFF; Curv1 = 370.00 MPa and 72,510 cycles/Curv2 = 340.00 MPa and 61,000 cycles). Flat preparations improve the mechanical performance of bonded leucite-reinforced glass-ceramic restorations compared to curved preparations, which exhibit higher stress concentrations and reduced fatigue resistance.
Arcila et al. (Wed,) studied this question.