• Warangkana Butdee
• Kanchana Kanchanatawewat

Objective  The aim of this study was to evaluate the effect of surface finish on the flexural strength of feldspathic porcelain.

Materials and methods  135 feldspathic porcelain bars were randomly divided into 9 groups, 15 bars per group. The groups consisted of 1) as-fired at 920°C under vacuum; 2) self-glazed at 910°C in air; Group 3-9 were first polished with SiC paper under a wet condition; 3) polished with SiC paper; 4) overglazed at 890°C in air; 5) ground with a coarse and a fine diamond burs under a speed of 120,000 rpm in a wet condition; Group 6-9 were polished in a dry condition under a speed of 7,000 rpm; 6) polished with silicone rubber points and a felt disc impregnated with diamond paste; 7) polished with discs and a felt disc impregnated with diamond paste; 8) polished with silicon rubber points and diamond paste and 9) polished with discs and diamond polishing paste. Bars were subjected to a tree-point-bend testing according to ASTM C 1161-90. One way ANOVA and Tukey HSD test were performed on the data at p < 0.05.

Results  The results indicate that surface finish of either a polishing or an overglazing significantly increase the flexural strength of all tested porcelain bars.

Conclusion  Surface finish does have a positive effect on the flexural strength of feldspathic porcelain bars.

(CU Dent J 2001;24:101-10)