Efficacy of Yttrium (III) Fluoride Nanoparticles in Orthodontic Bonding

Our study evaluated the adhesion strength and antibacterial effect of a conventional orthodontic composite resin blended with yttrium fluoride (YF₃) nanoparticles. Yttrium fluoride nanoparticles (NP) were added to the conventional orthodontic composite resin (Transbond XT) at concentrations of 1%, 2%, and 3% (w/w), and the blended composite resins were labeled as NP1, NP2, and NP3, respectively. A total of 60 extracted human premolars was randomly allocated to four groups of 15 samples (n = 15). Orthodontic brackets were bonded using the conventional (control) and experimental composite resins (NP1, NP2, and NP3). The adhesion strengths of the composite resins were determined using a universal testing machine. The debonding sites were assessed and scored using the adhesive remnant index (ARI). The antibacterial effect of YF₃ nanoparticles against Streptococcus mutans was assessed by the viable cell counting method. For the same, 40 composite disc specimens were prepared using the control and experimental composite resins (n = 10). The data was analyzed by one-way ANOVA and Tukey's post hoc analysis. In all the tests, the significance level was determined to be 0.05. The highest adhesion strength values were found in the control group (11.61±0.23) and the lowest values were found in the NP3 group (10.49±0.17). A significant difference was observed between the control and experimental groups, NP2 and NP3 (P < 0.05). NP1 group showed insignificant (P = 0.388) adhesion strength values compared with the control group. There was no significant difference between the ARI scores of the conventional and experimental groups (P > 0.05). The highest colony forming units (CFU) were found in the control group (75.85±1.15) and the lowest CFU were found in the NP1 group (2.24±1.14). A significant difference between the mean CFU of the conventional and experimental composite groups was observed (P < 0.05). Despite higher antibacterial activity in the NP1 group compared with NP2 (P = 0.146) and NP3 (P = 0.117), the difference was not significant. Similarly, no significant difference was observed between NP2 and NP3 groups (P = 0.97). Our results suggested that yttrium fluoride nanoparticles, blended with a conventional resin at 1% concentration, demonstrated significant antibacterial effect and did not compromise adhesion strength.