Abstract
The aim of the present study was to evaluate the in vitro cytotoxicity of self-adhesive dual-cured resin cement (SADRC) polymerized beneath three different cusp inclinations of zirconia with different light curing time. A commercial SADRC (Multilink Speed) was polymerized beneath zirconia (ZrO2) with three different cusp inclinations (0°, 20°, and 30°) for 20 s or 40 s. After being stored in light-proof box for 24 h, the ZrO2-SADRC specimens were immersed in DMEM for 72 h and then we got the extract solution, cultured the human gingival fibroblasts (HGF, 8 × 103 per well) with 100% or 50% concentrations of the extract solution for 24 h, 72 h, and 120 h, respectively, and evaluated cytotoxicity of the polymerized SADRC with CCK-8 assay in optical density (OD) values, relative growth rates (RGR), and cytotoxicity grades. Statistical analysis was conducted using a two-way ANOVA followed by post hoc Student–Newman–Keuls test. The OD values varied from 0.8930 to 3.2920, the RGR varied from 33.93% to 98.68%, and the cytotoxicity grades varied from 0 to 2. There was significant difference in the OD values among the different cusp inclinations of zirconia (P < 0.001), and there was significant difference in the OD values between the different light curing times in some situations (P < 0.05). The cusp inclination of zirconia affects the in vitro cytotoxicity of SADRC. Prolonging the light curing time from 20 s to 40 s can reduce the in vitro cytotoxicity of SADRC when the cusp inclination of zirconia is smaller than 20°.
Highlights
Because of its excellent mechanical and biocompatibility properties [1], yttria stabilized tetragonal zirconia polycrystal (Y-TZP, hereafter simplified to zirconia) has been increasingly used in dentistry [2]
Tooth cusps are the main structures of the restorations surface, so the present study focuses on the in vitro cytotoxicity of Self-adhesive dualcured resin cement (SADRC) polymerized beneath zirconia with three different cusp inclinations
The optical density (OD) values, relative growth rates (RGR), and cytotoxicity grades of all experimental groups are shown in Tables 3, 4, and 5 and Figure 4
Summary
Because of its excellent mechanical and biocompatibility properties [1], yttria stabilized tetragonal zirconia polycrystal (Y-TZP, hereafter simplified to zirconia) has been increasingly used in dentistry [2]. Adhesive resin cements exhibit good biocompatibility, less edge microleakage, good mechanical properties, and excellent esthetic properties and are the most commonly used luting agents for bonding to restoration [4, 5]. Self-adhesive dualcured resin cement (SADRC), which is easy to use and possesses improved properties, is currently popular luting material in dentistry [7, 8]. Light curing is important for SADRC [12]. It affects the polymerization efficiency of dual-cured resin cement through high translucent zirconia [13]. Curing time [14], type of light curing unit [15], type of initiator [16], the type [17], and thickness [18] of the restoration can influence the polymerization of dual-cured resin cement
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