Evaluation of Discolouration of Some Composite Restorative Materials

This in-Vitro study was conducted to investigate the stain resistance of direct composite resin restorative materials with different polishing systems (diamond finishing and polishing burs, aluminium oxide disks and abrasive impregnated disks) in comparison to the material cured against a mylar strip. The composite resin materials investigated included Clearfil AP-X (hybrid), Filtek Z-250 (hybrid), Definite (Ormocer), and Silux Plus (microfill). Forty disk specimens (10 mm x 2 mm) of each composite resin were prepared. Ten mylar cured specimens were assigned for each polishing system and ten were used as controls with no further treatment after curing. A spectrophotometer (Spectraflash 500) was used to determine the initial colour and the colour change after one week immersion. All specimens were stored in tea separately for one week at 39 °C. Post immersion colour measurements were undertaken to assess colour change (Δ E). One way ANOVA showed that there was statistically significant difference between the different composites and the polish groups for discoloration at p < 0.05. All the composites tested showed significant discoloration when polished with Diamond burs. The least discoloration was found when specimens were polished with soflex except with Z-250 which discoloured less under mylar than soflex but the difference was not significant. Among the materials tested AP-X showed the least discoloration.