Characterization, Shear Bond Strength Assessment, and Antibacterial Effects of an Orthodontic Composite Containing...

Background This study aimed to determine the antibacterial properties of orthodontic adhesive infused with stannous oxide nanoparticles (NPs) against Lactobacillus acidophilus and Streptococcus mutans bacteria, along with assessing the shear bond strength (SBS) of this composite when compared to conventional, non-infused composites. Methods A concentration of 1% w/w tin dioxide NPs (SnO₂ NPs) was added to Transbond XT Orthodontic Adhesive. This modified composite material was used to prepare composite discs for the evaluation of its antibacterial properties against L. acidophilus bacteria and S. mutans bacteria using the biofilm inhibition test. To evaluate the SBS of this modified adhesive material, 50 extracted premolar teeth were collected and divided into two groups, with 25 teeth in each group (n = 25). Orthodontic stainless steel brackets were bonded to these extracted teeth using the modified composite. A comparative analysis of the SBS of the nano-infused composite group was then performed against that of the control group using an Instron universal testing machine. Results Growth inhibition zones were produced around the composite discs infused with SnO₂ NPs for both bacterial strains. After performing the biofilm inhibition test, it can be inferred that the nano-infused composite is capable of inhibiting the bacterial count better than the control group. A statistically significant difference was observed between the two groups, with the SBS of the nano-infused composite being higher (16.89 MPa) than the non-infused composite adhesive (15.49 MPa). Conclusion The antibacterial activity of orthodontic composites modified with SnO₂ NPs was significant compared with conventional composites. The control group showed less SBS when compared to the NP-infused composite, with a statistically significant difference in mean SBS values between both groups.