Evaluation of the Mirror-polished Surface Characteristics and the Alkaline Deterioration Behavior of the Various Latest Composites

Abstract

 Purpose: This study comprehensively assessed the mirror-polished surface characteristics of the various latest composites, examining the correlation between surface roughness, glossiness, color change and contact angle, and evaluating the bonding state between fillers and matrix resin under alkaline conditions.
 Methods: The following seven composites were used: Clearfil AP-X (AP), Estelite Σ Quick (EQ), Clearfil Majesty ES-2 (ES), MI Gracefil (GF), Filtek Supreme Ultra (FS), Clearfil Majesty ES Flow (ESf) and MI Fil (MF). The surface roughness (Ra), glossiness (%), color change (ΔE^*ab) and contact angle (θ) of the mirror-polished surface of each composite were examined, and the correlations between them were assessed (Tukey’s HSD test, Pearson’s correlation test, α=0.05). These composites with a mirror-polished surface were immersed in 0.1 N NaOH solution (60°C, pH 12.7) for 3 days. The deteriorated surface and cross-section were examined by SEM focusing on the structural changes.
 Results: EQ and MF exhibited lower surface roughness than ES and FS. The lowest glossiness was observed in AP and the highest change of color in FS (p<0.05) compared with the other composites. Surface roughness and glossiness, and surface roughness and color change, exhibited significant correlations (p<0.05). The alkaline deterioration test demonstrated small gap formation between filler particles and matrix resin, and exfoliation and falling of filler particles. These structural changes were observed with varying degrees depending on each composite.
 Conclusion: This study revealed that both the mirror-polished surface characteristics and the alkaline deterioration behavior of the various latest composites might be closely associated with type of filler, particle size and its distribution.