Compressive Strength of CEREC-Crowns over Build-ups of Amalgam and Composite

Objectives: To compare compressive strength of CEREC crowns over amalgam build ups using conventional metallic screwed pins and composite build ups with the experimental Dentin Anchor® a fiber reinforced composite (FRC) anchor. Methods: Twenty sound maxillary premolars were selected. Teeth were embedded in PMMA and had removed the lingual cusp. Core build-ups were performed according to the groups: G1: Amalgam build-ups with metallic screwed pin (MPA) and G2: Composite build-ups with Dentin Anchor® (DAC). Both anchorage systems were placed into the dentin 1.0mm away from the dentin-enamel junction. After 24h of storage in distilled water at 37ºC, the samples were prepared to receive standardized CEREC crowns using the CEREC 3 system. Crowns were cemented using Nexus® (Kerr). After 24h in water at 37ºC, the samples were tested for compressive strength until failure using a Universal Testing Machine (0.5mm/min). Data was recorded in Newtons (N) and analyzed by Student t-test (p<0.05). Results: Compressive strength values for each group, mean (standard deviation): G1: 573.1(73.89); G2: 546.6(99.88). The analysis indicated there were no significant differences in compressive strength between the two groups. Conclusion: Within the limits of this in vitro testing, compressive strength of CEREC crowns demonstrated similar values for both build-up techniques.