Assessment of the Ability of Different Cleaning Protocols to Remove Eugenol-based Endodontic Sealer from the Root Dentin

Abstract

Aim:The aim of this study is to assess three protocols for removing a eugenol-based filling endodontic sealer from root dentin and the bond strength of fiberglass posts luted with resin cement. Materials and methods: Sixty single-rooted bovine teeth were prepared and filled with the Endofill endodontic sealer and gutta-percha cones. After 7 days, 9 mm of the filling was removed and divided into five groups (n = 12) according to the cleaning protocol: G1 (negative control), unfilled; G2 (positive control), saline solution; G3, 95% alcohol; G4, amyl acetate; and G5, Largo bur. The canals were hybridized and fiberglass posts were luted with resin cement. They were cross-sectioned in slices of 1 mm and subjected to the push-out test. The other samples were sectioned longitudinally and visualized in a scanning electron microscope (SEM), and the existing chemical elements were quantified by energy dispersive spectroscopy (EDS). The statistical analysis used variance analysis (ANOVA)-one way and Fisher's test, at a 5% significance level. Results: The 95% alcohol was more effective for cleaning the canal, resulting in a clean dentinal surface and bond strength statistically similar to the negative control. The Largo bur was also statistically similar to the negative control, with only a few debris impregnated on the wall. Amyl acetate showed more sealer residues on the canal walls, with a consequent lower bond strength value than the other groups, only higher than the positive control. Conclusion:The 95% alcohol and Largo burs may be used after removing the canal filling, so that the bond strength is improved when using the eugenol-based sealer.

Impact of cleansing protocols to remove endodontic sealer residues on the adhesive interface: Bonding with universal adhesive systems

“…The persistence of sealer residues within the pulp chamber dentin is a current concern in restorative treatments. 3,11,15 Prior to restorations, endodontically-treated teeth should receive a glass fiber post and an adhesive cementation in most cases. Furthermore, to achieve an ideal dentin sealing, the surface has to be prone for bonding.…”

“…Thus, the chemical interaction of both solvent/solute must present similar polarity in order to work efficiently, following the rule “polar dissolves polar.” 5,7,8 The persistence of residues on the dentin surface is left by epoxy resin‐based sealers, which have been widely used in root canal obturation due to their satisfactory physico‐chemical and biological properties 13,14 . In addition, bisphenol A diglycidylether, which is non‐polar solute, is used as a constituent of epoxy resin, and it is poorly soluble in ethanol (polar solvent) 6,7,13,15,16 . Therefore, to clean the residues left on the dentin surface after root canal obturation, xylol and formamide, which are non‐polar compounds, have been recommended as an alternative substance; however, they are considered toxic substances 6,7,10,14,17 …”

“…13,14 In addition, bisphenol A diglycidylether, which is nonpolar solute, is used as a constituent of epoxy resin, and it is poorly soluble in ethanol (polar solvent). 6,7,13,15,16 Therefore, to clean the residues left on the dentin surface after root canal obturation, xylol and formamide, which are non-polar compounds, have been recommended as an alternative substance; however, they are considered toxic substances. 6,7,10,14,17 Although xylol showed to be more effective in removing epoxy resin-based sealers than 95% ethanol, it is also important to allow the epoxy resin-based sealers to fully set before etching.…”

Cleaning and microstructural effects of amyl acetate on pulp chamber dentin impregnated with epoxy resin‐based endodontic sealer

“…Hypothetically, the combination of both solutions would be ideal. However, when amyl acetate and ethanol are mixed in a 1:1 ratio (E2), a significant persistence of residues was observed (Figures 1 and 2), probably because 95% ethanol has a portion of water that lower the miscibility with nonpolar substances presented in epoxy resin‐based sealers, such as bisphenol A and B 1,8,15 …”

“…An alternative solution to remove epoxy resin‐based sealer residues from dentin surface is amyl acetate (AA), 8,12,14 which is a nonpolar solvent. AA does not successfully remove zinc oxide and eugenol sealer residues from root canal dentin 15 . However, the use of AA for cleaning the pulp chamber dentin and their microstructural effects are still controversial, requiring further investigations 8 …”