Optical properties and colorimetric evaluation of resin cements formulated with thio‐urethane oligomers

• Published in: Journal of esthetic and restorative dentistry 2019-03, Vol.31 (2), p.153-159
• Main Authors: Bacchi, Atais, Caldas, Ricardo Armini, Cesar, Paulo Francisco, Pfeifer, Carmem Silvia
• Format: Article
• Language: English
• Subjects: Benzene; Color; colorimetric evaluation; Colorimetry; Composite Resins; Dental restorative materials; Dentistry; Elastic Modulus; Ethyl carbamate; Fluorescence; Isocyanates; Materials Testing; Optical properties; Periodontics; Resin Cements; Stress, Mechanical; Studies; Thiols; thio‐urethane oligomers; Ultraviolet radiation; Urethane
• ISSN: 1496-4155; 1708-8240
• DOI: 10.1111/jerd.12437

Objective The aim of this study was to evaluate the color parameters and optical properties of resin cements (RCs) formulated with thio‐urethanes (TUs). Materials and methods Six TUs were synthesized by combining thiols (pentaerythritol tetra‐3‐mercaptopropionate [PETMP] or trimethylol‐tris‐3‐mercaptopropionate [TMP]) with di‐functional isocyanates (1,6‐Hexanediol‐diissocyante [HDDI] [aliphatic‐AL] or 1,3‐bis(1‐isocyanato‐1‐methylethyl) benzene [BDI] [aromatic‐AR] or Dicyclohexylmethane 4,4′‐Diisocyanate [HMDI] [cyclic‐CC]). TUs (20 wt%) were added to a BisGMA/UDMA/TEGDMA matrix. Filler was introduced at 60 wt%. Fluorescence was evaluated through an UV‐light emitting equipment. Coordinates L*, a*, and b* were obtained in the black and white reflectance to evaluate the contrast ratio (CR) and translucency parameter (TP00). The coordinates obtained from transmittance were used to evaluate lightness (L*), chroma (C*), color difference (ΔE00) after 6 month, and whiteness index for Dentistry (WID). Results RCs formulated with TUs presented significantly higher CR, and fluorescence (with T_AR). Significantly lower C*, L*, and TP00 (except for P_AR and T_AL) were also observed in RCs containing TUs. ΔE00 were not significant among the materials. WID was not influenced. Conclusion RCs composed by TU oligomers present higher CR and lower translucency. The material also present higher fluorescence depending on the oligomer used. Clinical Significance The use of thio‐urethanes to formulate resin cements can ensure a luting material with improved potential to mask colored substrates due to the higher contrast ratio and lower translucency obtained. A final higher fluorescence of restoration is also expected with the use of specific oligomer.