The effect of oxygen-inhibited layer and its inhibition technique on diametral tensile strength values of various nanofilled composite resin types

Abstract

Abstract Aim: To investigate the impact of different inhibitory techniques on the thickness of oxygen-inhibited layer (OIL) and diametral tensile strength (DTS) value in various types of nanofilled composite resins. Materials and Methods: Thirty-six nanofilled composite resins specimens, consisting of packable, flowable, high-viscosity bulk-fill (HVBF), low-viscosity bulk-fill (LVBF), shaped as half disk (diameter: 6 mm and height 3 mm) and randomly allocated to three groups (n = 3): with Mylar strip, glycerin application, and without OIL inhibitors. OIL thickness was observed with an optical microscope. Furthermore, 60 specimens of composite resins were incrementally created in disk-shaped molds (diameter: 6 mm, height: 1.5 mm × 2 mm). DTS measurements were carried out using a universal testing machine. Data were statistically analyzed using a two-way analysis of variance (ANOVA) test and Pearson’s correlation test (P < 0.05). Results: OIL inhibitor techniques (Mylar strip and glycerin) significantly affected OIL formation across various types of nanofilled composite resins (P < 0.05). Changes were also observed in how these techniques influenced DTS values. Correlation analysis indicated a positive relationship between OIL thickness and DTS value. Conclusions: Application of Mylar strip and glycerin reduced OIL thickness and DTS values in packable, flowable, HVBF, LVBF nanofilled composite resins. Glycerin proved to be more effective than Mylar strips in reducing OIL thickness, which is reflected in the DTS values of nanofilled composite resins. Greater OIL layer thickness on the outermost layer of the nanofilled composite resin correlated with a higher DTS value.