Color stability of three bonding agents

Methods:Bonding agents investigated were: One-up Bond F (OB/Tokuyama), Prompt L-Pop (PL/3M Espe) and Optibond Solo Plus (OS/Kerr). 10 sample disks, 6mm in diameter and 1mm in thickness, of each material were prepared (OB1, LP1 OS1). Additionally, 30 sample discs, with the same dimensions, of A2 shade TPH Spectrum (Caulk/Dentsply) resin composite were prepared and bonded with the three selected bonding agents (3 groups of 10 samples each OB2, LP2 OS2) to freshly cut dentin discs (1mm in thickness). 30 days of storage in deionised water at 37+1oC, in dark conditions was followed by exposure to UV light photoaging (BT: 55±5oC, E: 400W/m2, WT: 37±1oC). Colorimetric measurements, according to the CIEL*a*b* system, were performed right after sample photopolymization (0 - baseline), at 7 and 30 days of dark/water storage and after the 360hour of UV aging. Color changes (Ä E*) were calculated between baseline and subsequent measurements. The results were analyzed by two-way Anova and Sheffe's statistical tests (a=0.05).

Results: Results are showed in Table1: All three bonding agents exhibited color changes under dark/water and photoaging conditions prolonged with time. In dark/water and photoaging conditions, OB showed the highest color changes. Resin composite bonded to the dentin discs with the three different bonding agents showed color changes under both dark/water and photoaging conditions which were significantly lower than the color changes showed by the bonding agents themselves. Resin composite bonded with OB showed significantly higher color change than with LP and OS.

Conclusions: Bonding agent systems reveal color changes which may alter color stability of resin composite restorations.