Degree of conversion and adhesion of methacrylate-based resin cements with phosphonic or phosphoric acid acrylate to glass fiber posts at different regions of intraradicular dentin

Abstract

(2016). Degree of conversion and adhesion of methacrylate-based resin cements with phosphonic or phosphoric acid acrylate to glass fiber posts at different regions of intraradicular dentin. Journal of Adhesion Science and Technology, 30(3):328-337. DOI: https://doi.org/10. 1080/01694243.2015.1105122 Degree of conversion and adhesion of methacrylate-based resin cements with phosphonic or phosphoric acid acrylate to glass fiber posts at different regions of intraradicular dentin Zürich, 2 Abstract: This study evaluated the degree of conversion (DC) and adhesion of methacrylate-based resin cements to glass fiber posts at different regions of intraradicular dentin. Single-rooted teeth (N=24, n=12per group) were cut at the cement-enamel junction (CEJ), endodontically treated and post space (depth= 8 mm) was prepared. Teeth were randomly divided into two groups according to the resin cements: a) Group ML: Methacrylate-based cement with phosphonic acid acrylate (Multilink Automix, Ivoclar Vivadent); b)Group RXU: Methacrylate-based cement with phosphoric acid acrylate (RelyX Unicem 2 Automix, 3M ESPE). Fiber reinforced composite root posts (RelyX Fiber Post, 3M ESPE) were cemented according to the manufacturers' instructions of the resin cements. Root slices of 2 mm thick (n=3 per tooth) were cut below the CEJ 1, 3, 5 mm apically. The DC of each section was analyzed with micro-Raman spectrometer and push-out test was performed in the Universal Testing Machine (0.5 mm/min). After debonding, all specimens were analyzed using optical microscope to categorize the failure modes. While data (MPa)were statistically evaluated using Kruskal Wallis, Mann-Whitney U tests, for DC data 3-way ANOVA and Tukey`s tests were used (α=0.05). Regardless of the resin cement type, the mean push out bond strength results (MPa), were significantly higher for the coronal slices (ML: 9.1±2.7; RXU: 7.3±4.1) than those of the most apical ones (ML: 7±4.9; RXU: 2.89±1.5) (P=0.002). Resin cement type and (P<0.001) root level (P=0.002) significantly affected the DC values, while the interaction terms were not significant (P=0.606).Overall, DC was significantly higher for ML (67±8.2%) than RXU (26±8.8%) (P<0.001). Adhesive failures at the cement-dentin interface were more commonly experienced in RXU than in ML, whereas ML presented more incidences of adhesive failures at the cement-post interface. Considering the push-out bond strength, degree of conversion and failure types, methacrylate-based cement with phosphonic acid acrylate should be preferred to those containing phosphoric acid to adhere glass fiber posts in the root canal.

Can fiber-reinforced resin composites alone substitute adhesively luted intraradicular post and core materials under static and dynamic loading?

“…This adaptation and durable adhesion were expected to reduce the risk of reinfection and achieve a homogeneous monobloc structure [8]. As a consequence of light transmission properties, they could be polymerized at a certain depth in the root canal, which also increases their stiffness [10,11]. The use of FRC posts are considered as an integral part of minimal invasive dentistry, since they could be adhesively bonded to the root canal dentin, do not require extensive root canal preparation, preserve the root structure and cause less root fracture [9].…”

“…For this reason, the concept of using a post is being substituted with direct filling of the root canal with a resin composite and restoring the core with the same material [15]. Since the morphology of the FRC posts do not completely fit to the root morphology, usually the luting cement occupies a large space in the root and thereby yield to more shrinkage [5,11].…”

Adhesion of bulk-fill resin composites as core and intraradicular post materials only versus the use of glass-fiber posts in different regions of root dentin

“…This adaptation and durable adhesion were expected to reduce the risk of reinfection and achieve a homogeneous monobloc structure [10]. As a consequence of light transmission properties, they could be polymerized at a certain depth in the root canal, which also increases their stiffness [11,12].…”

Surface morphology and mechanical properties of conventional and self-adhesive resin cements after aqueous aging

“… 11 The concentration of acidic monomers in the self-adhesive resin cement should be considerably low to avoid excessive hydrophilicity in the final polymer, and sufficiently high to achieve an acceptable bonding to the dentin and enamel. 12 Following their initial mixture, the selfadhesive resin cements are fairly hydrophilic, which facilitates their wetting conditions and their adaptation to the tooth surface. Nevertheless, the materials become more hydrophobic as the acid functionality is consumed via reaction with tooth calcium ions and due to effects of various metal oxides from the ion- leachable fillers.…”