The effect of resin cement type and cleaning method on the shear bond strength of resin cements for recementing restorations

PURPOSE: This laboratory study assessed the effect of different dentin cleaning procedures on shear bond strength of resin cements for recementing prosthesis. MATERIALS AND METHODS: 4 × 4 flat surface was prepared on the labial surface of 52 maxillary central incisors. Metal frames (4 × 4 × 1.5 mm) were cast with nickel-chromium alloy. All specimens were randomly divided into 2 groups to be cemented with either Panavia F2.0 (P) or RelyX Ultimate (U) cement. The initial shear bond strength was recorded by Universal Testing Machine at a crosshead speed of 0.5 mm/min. Debonded specimens were randomly allocated into 2 subgroups (n = 13) according to the dentin cleaning procedures for recementation. The residual cement on bonded dentin surfaces was eliminated with either pumice slurry (p) or tungsten carbide bur (c). The restorations were rebonded with the same cement and were subjected to shear test. Data failed the normality test (P < .05), thus were analyzed with Mann Whitney U-test, Wilcoxon signed rank test, and two-way ANOVA after logarithmic transformation (α = .05). RESULTS: The initial shear bond strength of group P was significantly higher than group U (P = .001). Pc and Uc groups presented higher bond strength after recementation compared to the initial bond strength. However, it was significant only in Pc group (P = .034). CONCLUSION: The specimens recemented with Panavia F2.0 provided higher bond strength than RelyX Ultimate cement. Moreover, a tungsten carbide bur was a more efficient method in removing the residual resin cement and increased the bond strength of Panavia F2.0 cement after recementation.

Influencia de los inhibidores de las metaloproteinasas, agentes reticuladores y remineralización biomimética en la longevidad de la unión adhesiva: parte 3: agentes reticuladores / Metalloproteinase inhibitors, cross-linking agents and biomimetic remineralization influence in the adhesive bond longevity: part 3: cross-linking agents

Las propiedades mecánicas del colágeno se deben a agentes intrínsecos de entrecruzamiento [Al-Ammar et al, 2009]. El aumento en el número de enlaces de la molécula de colágeno mejora su estabilidad e integridad, colaborando con el mantenimiento de propiedades adecuadas de la unión adhesiva a lo largo del tiempo [Bedran-Russo et al, 2009; Breschi et al, 2008]. Existen varios enfoques que permiten modificar el sustrato dentinario mediante la promoción de la formación de enlaces exógenos, con el objetivo de aumentar la resistencia de la red de colágeno [Bedran-Russo et al, 2007; Bedran-Russo et al, 2008]. Estos enfoques se dividen en métodos mecánicos [Bedran-Russo et al, 2007; Bedran-Russo et al, 2008; Castellan et al, 2010; Han et al, 2003] y método fotoxidativo [Cova et al, 2011]. Dentro de los primeros, los agentes reticuladores de origen natural son capaces de estabilizar el colágeno de la dentina [Bedran-Russo et al, 2007] sin afectar la resistencia de la unión adhesiva y sin generar toxicidad. Sin embargo, el uso de estos agentes por sí solo no permite asegurar la estabilidad de la unión adhesiva a lo largo del tiempo; porque como es sabido, la longevidad de dicha unión no depende únicamente de las características del sustrato, sino también de propiedades inherentes al sistema adhesivo por un lado, y de la presencia de humedad por otro.

The mechanical properties of collagen are due to intrinsic crosslinking agents [Al-Ammar et al, 2009]. The increase in the number of links of the collagen molecule improves its stability and integrity, collaborating with the maintenance of adequate adhesive bonding properties over time [Bedran-Russo et al, 2009; Breschi et al, 2008]. There are several approaches for modifying the dentin substrate by promoting the formation of exogenous links, in order to increase the strength of the collagen network [Bedran-Russo et al, 2007; Bedran-Russo et al, 2008]. These approaches are divided into mechanical methods [Bedran-Russo et al, 2007; Bedran-Russo et al, 2008; Castellan et al, 2010; Han et al, 2003] and foto oxidating method [Cova et al, 2011]. Within the first, the naturally occurring crosslinking agents are capable of stabilizing the dentin collagen [Bedran-Russo et al, 2007] without affecting the strength of the adhesive bond and without generating any toxicity. However, the use of these agents alone does not ensure the stability of the adhesive bond over time; because as it is known, the longevity of such binding does not only depend on the substrate’s characteristics, but also on the adhesive system’s properties on one side, and the presence of moisture on the other