Effect of two matrix metalloproteinase inhibitors on the color stability of a nanofilled resin composite

Abstract

OBJECTIVES: This in vitro study evaluated the effect of two matrix metalloproteinase (MMP) inhibitors on the color stability of two shades of a nanofilled resin composite. METHODS AND MATERIALS: A total of 60 sound human molars were used in this study. Flat dentin surfaces were obtained by wet grinding the occlusal surfaces. Following acid etching, the molars were divided into three equal groups according to the MMP inhibitor used: Group 1: no inhibitor (control group), group 2: chlorhexidine digluconate based (CHX; Consepsis, Ultradent, South Jordan, UT, USA); group 3: doxycycline based (MTAD; Biopure, Dentsply TulsaDental, Johnson, TN, USA). Adper Single Bond 2 Adhesive (3M ESPE, St Paul, MN, USA) was applied to the treated dentin surfaces. Each group was then subdivided into two equal subgroups of 10 molars each, according to the shade of the resin composite (Filtek Z350 XT, 3M ESPE) used, either B1 or A3. The color was assessed for each subgroup at three times: baseline (after 24 hours); after aging using a total energy of 600 kJ/m(2) (Weather-Ometer Ci35A, Atlas Electronic Devices Company, Chicago, IL, USA); and then after a second period of aging, for a total energy of 1200 kJ/m(2). Color assessment was carried out using a spectrophotometer. Color change (ΔE) was calculated according to the Commission Internationale de l'Eclairage L*a* b* color scale, comparing each aging period with the baseline color measurement. Data were analyzed using repeated measures analysis of variance and Tukey post hoc test. RESULTS: All tested subgroups showed greater discoloration than the clinically acceptable level (3.3). MTAD induced the highest statistically significant color change, followed by CHX, whereas the control groups showed the lowest statistical ΔE values with both tested shades. Shade B1 subgroups showed higher ΔE values when compared with shade A3 subgroups. CONCLUSION: Accelerated aging caused color change in a nanofilled resin composite regardless of MMP inhibitor used. Furthermore, lighter shades showed less color stability when compared with darker shades.