Effectiveness of diamond-impregnated felt wheels for polishing a hybrid composite

The effectiveness of diamond-impregnated felt wheels for polishing the surfaces of a fine-particle hybrid composite was studied in relation to different finishing methods. Standardised composite specimens were finished with one or a series of two or three finishing diamonds (particle size 30, 15 and 8 microns), one or two tungsten carbide finishing burs (12- and 30-fluted) or with a finishing diamond followed by a tungsten carbide bur. The final polishing of all specimens was done with the diamond-impregnated felt wheel Diafix alpha. Treatment with Sof-Lex discs after the use of a finishing diamond served as a polishing standard for comparison. Evaluation of the final surfaces was done with profilometry and by scanning electron microscopy. The profilometric results showed that the type of pretreatment was decisive for the quality of the final polishing. Nearly all surfaces polished by the diamond-impregnated felt wheels were smoother than those treated by the flexible discs (P < 0.01). The lowest roughness data were recorded following a pretreatment with a finishing diamond and a tungsten carbide finishing bur. After appropriate pretreatment, the hybrid composite surface was sufficiently polished with the diamond-impregnated felt wheels.