Scanning electron microscopy analysis of marginal adaptation of composite resines to enamel after using of standard and gradual photopolimerization

Abstract

Bonding between composite and hard dental tissue is most commonly assessed by measuring bonding strength or absence of marginal gap along the restoration interface. Marginal index (MI) is a significant indicator of the efficiency of the bond between material and dental tissue because it also shows the values of width and length of marginal gap. The aim of this investigation was to estimate quantitative and qualitative features of the bond between composite resin and enamel and to determine the values of MI in enamel after application of two techniques of photopolymerization with two composite systems. Forty Class V cavities on extracted teeth were prepared and restored for scanning electron microscope (SEM) analysis of composite bonding to enamel. Adhesion to enamel was achieved by Adper Single Bond 2 - ASB (3M ESPE), or by Adper Easy One--AEO (3M ESPE). Photopolymerization of Filtek Ultimate--FU (3M ESPE) was performed using constant halogen light (HIP) or soft start program (SOF). Quantitative and qualitative analysis, showed better mikromorphological bonding with SOF photopolymerization and ASB/FU composite system. Differences in MI between different photopolymerization techniques (HIP: 0.6707; SOF: 0.2395) were statistically significant (p < 0.001), as well as differences between the composite systems (ASB/FU: 0.0470; AEO/ FU: 0.8651) (p < 0.001) by two-way ANOVA test. Better marginal adaptation of composite to enamel was obtained with SOF photopolymerization in both composite systems.