Comparative evaluation of microtensile bond strength in three different dentin luting agents: An in vitro study

Abstract

Aim: Long-term clinical success on indirect restorations is largely determined by bonding efficiency of the luting agent, with adhesion to dentin being the main challenge. Therefore, aim of this study was to assess the microtensile bond strength when using flowable resin composite, preheated resin composite and dual self-adhesive resin cement as dentin luting agents. Materials and Methods: Occlusal thirds of molar teeth were cut and randomly divided into 3 groups to be cemented: RelyX™U200, Filtek™ Z250 XT- preheated to 70° and Filtek Flow™ Z350XT. They were then thermocycled 5000 times between 5+/-2°C and 55+/-2°C. Subsequently, 10 microbars per group were prepared. The 30 samples were placed in saline solution for 24 hours at room temperature prior to microtensile test. This was performed with a digital universal testing machine at a crosshead speed of 0.5 mm/min. The bond strength values obtained were analyzed in Megapascals (MPa). Measures of central tendency such mean and measures of dispersion such standard deviation were used. In addition, the Kruskall Wallis non-parametric test with Bonferroni post hoc test was applied, considering a significance value of 5% (P < 0.05), with type I error. Results: The dentin microtensile bond strengths of preheated resin composite, flowable resin composite and dual self-adhesive cement were 6.08 ± 0.66 Mpa, 5.25 ± 2.60Mpa and 2.82 ± 1.26Mpa, respectively. In addition, the preheated resin composite exhibited significantly higher microtensile bond strength compared to the dual self-adhesive cement (P < 0.001). While the flowable resin composite showed no significant difference with the dual self-adhesive cement (P = 0.054) and the preheated resin composite (P = 0.329). Conclusions: The microtensile bond strength in dentin was significantly higher when using a preheated resin composite at 70°C as a luting agent compared to dual self-adhesive cement. However, the preheated resin composite showed similar microtensile bond strength compared to the flowable resin composite.

Effect of Polywave and Monowave Light Curing Units on the Microtensile Bond Strength and Failure Types of Different Bulk-Fill Resin Composites: An in vitro Study

“…Finally, before sectioning the occlusal third of the molar teeth using a micromotor (DREMEL ® 3000 Series, Mt. Prospect, Illinois, USA) with a water-cooled diamond cutting disc, all the teeth were placed in saline solution for 24 h at 37°C ± 2°C 29 [ Figure 2 ].

Figure 2 Preparation of microbars for microtensile bond strength testing.

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“…Horizontal and vertical cuts were performed using a water-cooled diamond cutting disc at a low speed, and the disc was changed every 5 cuts. 29 The dimensions of the microbars were 1×1 × 8 mm, 29 , 30 ,32 with n = 15 per group. The measurements were performed using a digital calliper (Mitutoyo, Kawasaki, Kanagawa, Japan).…”

“…Finally, before sectioning the occlusal third of the molar teeth using a micromotor (DREMEL ® 3000 Series, Mt. Prospect, Illinois, USA) with a water-cooled diamond cutting disc, all the teeth were placed in saline solution for 24 h at 37°C ± 2°C 29 [Figure 2]. For conditioning, etching acids were used: 37% Eco-Etch ® (Ivoclar Vivadent, Schaan, Liechtenstein), Condac 37 (FGM, Santa Catarina, Brazil), ScotchbondTM Etchant (3M ESPE, Saint Paul, USA), performing acid etching for 15 seconds, then washed with water for 10 seconds and dried the excess moisture with cotton.…”