Push-out bond strength and SEM evaluation of a new bonding approach into the root canal

Abstract

ObjectiveThis study evaluated the performance of different adhesive systems in fiber post placement aiming to clarify the influence of different hydrophobic experimental blend adhesives, and of one commercially available adhesive on the frictional retention during a luting procedure. Material and MethodsOne luting agent (70 Wt% BisGMA, 28.5% TEGDMA; 1.5% p-tolyldiethanolamine) to cement fiber posts into root canals was applied with 4 different adhesive combinations: Group 1: The etched roots were rinsed with water for 30 s to remove the phosphoric acid, then rinsed with 99.6% ethanol for 30 s, and blotdried. A trial adhesive (base to catalyst on a 1:1 ratio) was used with an experimental luting agent (35% Bis-GMA, 14.37% TeGDMA, 0.5% eDMAB, 0.13% CQ); Group 2: A trial adhesive (base to catalyst on a 1:2 ratio) was luted as in Group 1; Group 3: One-Step Plus (OSP, Bisco Inc.) following the ethanol bonding technique in combination with the luting agent as in Group 1; Group 4: OSP strictly following the manufacturer's instructions using the luting agent as in Group 1. The groups were challenged with push-out tests. Posted root slices were loaded until post segment extrusion in the apical-coronal direction. Failure modes were analyzed under scanning electron microscopy. ResultsPush-out strength was not significantly influenced by the luting agent (p>0.05). No statistically significant differences among the tested groups were found as Group 1 (exp 1 - ethanol-wet bonding technique)=Group 2 (exp 2 - ethanol-wet bonding technique)=Group 3 (OSP - ethanol-wet bonding technique)=Group 4 (control, OSP - water-wet bonding technique) (p>0.05). The dominating failure modes in all the groups were cohesive/adhesive failures, which were predominantly observed on the post/luting agent interface. ConclusionsThe results of this study support the hypothesis that the proposal to replace water with ethanol to bond fiber posts to the root canal using highly hydrophobic resin is plausible, but this seems to be more the proof of a concept than a clinically applicable procedure.

Influence of ethanol on dentin roughness, surface free energy, and interaction between AH Plus and root dentin

“…20 This technique has been shown to produce adhesive interfaces with higher bond strength, reduced interface nanoleakage, and increased stability over time when compared to the "water-wet bonding technique." 21,22 In endodontics, it is suggested that a final rinse of dentin walls with different substances 23 or with ethanol may alter root dentin properties, enhancing endodontic sealer penetration into dentinal tubules. 24,25 The interaction between a hydrophobic sealer and a surface with higher hydrophobic characteristics would provide a low contact angle, higher sealer penetration, greater mechanical interlock into the tubules, retention, sealing ability and, consequently, in vivo antibacterial effectiveness.…”

Effect of ethanol-conditioned dentine on sealer penetration into dentinal tubules

“…Moreover, the ethanol solution was used to condition the root canal prior to filling 8 or bonding 14 , instead of dehydrating the dentine using a technique known as 'ethanol wet-bonding'. Conditioning of the dentine promotes a surface with hydrophobic characteristics.…”

“…Ethanol solution is a dehydrating agent 10 that has been tested to improve dentine wettability and to increase sealer penetration along the root canal walls 8 . Some authors suggest there is a higher compatibility between ethanol-saturated dentine and hydrophobic resin monomers, preventing collagen shrinkage and allowing for higher impregnation 11 , infiltrating hydrophobic monomers into the demineralised dentine collagen matrix [12][13][14] . The use of 70% or 100% ethanol increased dentine wettability and improved the interaction between resin-based endodontic sealer and dentine root canal walls 15 .…”

Push-out bond strengths of fiber-reinforced composite posts with various resin cements according to the root level

“…For the post loading, three different punch pins with diameters of 0.8 mm, 1.0 mm, and 1.2 mm were used for the apical, middle, and coronal samples, respectively. The posts inside the specimens were loaded on the apical to coronal direction 27. The maximum failure load was measured in newtons (N) and divided by the bonding surface calculated using a formula of conical frustrum to obtain the bond strengths 20,21…”