Optical properties of composite restorations influenced by dissimilar dentin restoratives

Abstract

Objectives. To evaluate optical properties (color and translucency) of 'sandwich' restorations of resin-based composites and esthetically unfavorable dentin restoratives. Methods. Cylindrical 'dentin' specimens (8 mm in diameter and 2 mm thick, N = 5/group) were prepared using EverX Posterior (GC), Biodentine (Septodont), experimental hydroxyapatite (HAP) or conventional composites (Gradia Direct Posterior, GC; Filtek Z250 and Filtek Z500, 3M ESPE). Capping 'enamel' layers were prepared using composites (Gradia Direct Posterior, Filtek Z250 or Z550) of Al or A3 shade and the following thickness: 0.6, 1 or 2 mm. Color (Delta E) and translucency parameter (TP) were determined using a spectrophotometer (VITA Easyshade Advance 4.0, VITA Zahnfabrik). Data were statistically analyzed using analysis of variance with Tukey's post-hoc tests (alpha = 0.05). Results. TP was greatly affected by layer thickness, whilst Delta E depended on shade and layer thickness of the capping composite. HAP and Biodentine showed significantly lower TP and higher Delta E (deviation from 'ideal white') than composites (p lt 0.05). Greater TP was seen in EverX_composite groups than in corresponding control groups of the same shade and thickness. TP of composites combined with Biodentine or HAP was below 2, lower than the corresponding control groups (p lt 0.05). Within-group differences of Delta E were greatest in HAP_composite groups. EverX_Gradia and EverX_FiltekZ250 combinations showed the most comparable Delta E with the control groups. Significance. A 2 mm thick layer of composite covering dentin restoratives with unfavorable esthetics is recommended for a final 'sandwich' restoration that is esthetically comparable to a conventional, mono-composite control restoration.