The effect of tooth preparation height and diameter on the resistance of complete crowns to fatigue loading.
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This study investigated the relationship between tooth preparation height and diameter and the resistance of cemented crowns to dynamic loading. Crown and abutment analogs were cemented using zinc oxide-eugenol, zinc phosphate, glass-ionomer, and resin composite luting agents. Abutment height varied from 1 to 7 mm in increments of 1 mm. Diameters of 3, 4, 5, 6, 7, and 8 mm were tested. A testing apparatus designed to apply dynamic stresses was used. The cemented crowns were loaded until the cement bond failed or the components reached 1 million stress cycles. The staircase technique was applied for data analysis. The results showed that: (1) the relationship between abutment height (or diameter) and resistance to dynamic lateral loading is approximately linear; and (2) crowns luted using resin composite cement were more resistant than those placed using glass-ionomer cement, which in turn were more resistant than crowns cemented with zinc phosphate or zinc oxide-eugenol cements.