Impact of Titanium Oxide Nanoparticles on Microleakage and Bond Strength of Orthodontic Brackets: An In Vitro Analysis

The present study compares the microleakage and shear bond strength (SBS) of orthodontic brackets bonded with conventional composite resin and composite resin containing Titanium oxide (TiO2) nanoparticles after thermocycling. Eighty human extracted premolars bonded with 0.022 slot MBT brackets were divided into Group I (TiO2 nanoparticles composite) and Group II (conventional Transbond XT composite). After bonding, samples were thermocycled between 5°C and 55°C and evaluated for microleakage (stereomicroscope, 40X) and SBS (Universal testing machine). Adhesive Remnant Index (ARI) was scored under 10X magnification, and data was analyzed using a t-test and Chi-square test. The results showed that Group II (conventional composite) demonstrated higher shear bond strength (19.01 MPa) than Group I (15.05 MPa, p<0.001). Group II also showed lower microleakage (0.42 mm) than Group I (0.83 mm, p=0.01). Incisal microleakage was lower (p=0.16), with a higher ARI score (p=0.03) in the Group II samples. The current study revealed that the conventional composite resin (Transbond XT) has a higher shear bond strength and decreased microleakage compared to Titanium oxide nanoparticle incorporated composite within a clinically significant range. Conventional composite resin bonding also exhibited higher Adhesive remnant index scores, indicating a reduced risk of enamel damage during debonding.