Effect of natural and commercially produced juices on colour stability of microhybrid and nanohybrid composites

Objective: To evaluate the discoloration rate of microhybrid and nanohybrid resin composites after exposure to natural and commercially produced juices. Materials and Methods: Ninety disc specimens (2 mm × 10 mm) were prepared from a microhybrid composite (P4, Kerr, Italy) and a nanohybrid composite (Filtek Z250XT, 3M-ESPE, USA) (n=45 each; shade A2). Specimens of each composite were allocated to five subgroups (n=9) and immersed 10 days (4 h/day) in natural orange juice, commercially-produced orange juice, natural pomegranate juice, commercially-produced pomegranate juice, or distilled water (control), with storage in distilled water at 37 °C for the remaining 20 h/day. Colour was measured at baseline and after immersion using a reflective spectrophotometer (CIE L*a*b*), and ΔE was calculated. Results: Nanohybrid composites exhibited significantly higher discoloration than microhybrid when exposed to commercially-produced orange juice, natural pomegranate juice, and commercially-produced pomegranate juice (P<0.01). The highest ΔE for nanohybrid was with commercially-produced orange juice (ΔE=13.03), and for microhybrid with natural pomegranate juice (ΔE=4.79). Within nanohybrid, natural pomegranate juice caused higher ΔE than commercially-produced pomegranate juice (P=0.001), and commercially-produced orange juice caused higher ΔE than natural orange juice (P=0.010). Conclusions: Microhybrid composites showed greater colour stability than nanohybrid composites. Consumption of highly staining beverages—particularly natural pomegranate juice, commercially-produced orange juice, and commercially-produced pomegranate juice—is not recommended in the first few days after composite restoration.