Evaluation of the Shear Bond Strength of the Orthodontic Composites Modified with Various Concentrations of TiO2 Nanoparticles: An In vitro Study

Aim: This study aimed to evaluate the effect of various concentrations of TiO2 nanoparticles incorporation on the shear bond strength of the two different orthodontic composites.

Materials and Methods: A total of 80 freshly extracted premolars were divided into two groups of 40 teeth each. The extracted teeth in each of these two groups were further divided into four subgroups with ten teeth (n=10) in each, depending on the concentrations of TiO2 NPs (0.0%, 1.0%, 5.0% and 10.0%) in the Transbond XT and Enlight composites. Then the teeth were mounted in cold-cure acrylic resin poured into PVC tubes. The teeth were vertically embedded in acrylic up to the cementoenamel junction (CEJ), and a standard bonding procedure was carried out to bond the brackets using both composites. The shear bond strength was evaluated using a universal testing machine at a crosshead speed of 05mm/minute until the brackets de-bond from the tooth surface. The obtained data were subjected to statistical analysis using Oneway ANOVA and Posthoc tests.

Results: The control groups of both the composites showed more shear bond strength compared to the modified groups. One-way ANOVA showed significant differences (p=0.000) among the groups. Posthoc analysis showed significant differences between the control and modified groups and also between the modified groups in both the composites except between the control and 1.0 wt% and 5.0 and 10.0wt% groups of the Enlight composite.

Conclusion: A decrease in the shear bond strength was observed with an increase in the concentrations of TiO2 nanoparticles in both the composites.