Pretreatment of enamel with Riboflavin activated photodynamic therapy and Er, Cr: YSGG laser for bonding of orthodontic bracket with adhesive modified with cerium oxide nanoparticles.

ABSTRACT

AIM: To assess the degree of conversion (DC) and shear bond strength (SBS) of experimental adhesive (EA) infused with and without 1 % Cerium oxide (CeO2)-NPs on metallic bracket bonded to enamel conditioned with three different pretreatment regimes PDT-activated (Riboflavin) RF, ECY (Er, Cr YSGG), and Phosphoric acid (PA). MATERIAL AND METHOD: EA and EA modified with 1 % CeO2-NPs were prepared. Characterization of CeO2NPs was assessed using a scanning electron microscope (SEM). Seventy-two premolars extracted due to periodontal or orthodontic reasons were disinfected. Samples were mounted and allocated into three groups according to enamel surface treatment before bracket bonding. Samples in Group 1 were pretreated with Traditional 37 % PA-gel; Specimens in Group 2 surface treated with RF-activated PDT, and samples in Group 3 were conditioned using ECY. Brackets were placed on conditioned surfaces and samples were aged and underwent SBS testing using UTM. ARI index was used to assess bond failure. DC was evaluated for both adhesives using FTIR. ANOVA and Tukey post hoc test were used to compare the means and standard deviation (SD) of SBS and DC in different experimental groups. RESULTS: Enamel conditioned with PA and RF activated by PDT demonstrated comparable bond values with 1 % CeO2 infused in EA and EA (p>0.05).ARI analysis shows that enamel conditioned with PA and RF activated by PDT showed the majority of failure types between 1 and 2 irrespective of the type of adhesive. DC value in EA (73.28±8.37) was the highest and comparable to 1 % CeO2 infused in EA (66.48±6.81) CONCLUSION: RF-activated PDT can be used alternatively to 37 % PA for enamel conditioning when bonding metallic brackets. Infiltration of 1 % CeO2 NPs in EA improves SBS irrespective of the type of enamel conditioning. Infusion of 1 % CeO2 NPs in EA demonstrates no significant difference in DC compared to EA.