Contents lists available at ScienceDirect Journal of Dentistry journal homepage: www.elsevier.com/locate/jdent Antibacterial and remineralizing orthodontic adhesive containing quaternary ammonium resin monomer and amorphous calcium phosphate nanoparticles Yan Liu a,1 , Ling Zhang a,1 , Li-na Niu a,b,1 , Tao Yu a , Hockin H.K. Xu c,d,e , Michael D. Weir c , Thomas W. Oates c , Franklin R. Tay a,b, ⁎ , Ji-hua Chen a,b, ⁎⁎ a State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi’an, China b Department of Endodontics, Dental College of Georgia, Augusta University, Augusta, GA, USA c Department of Advanced Oral Sciences & Therapeutics, University of Maryland Dental School, Baltimore, MD, USA d Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD, USA e Department of Mechanical Engineering, University of Maryland, Baltimore County, MD, USA ARTICLE INFO Keywords: Adhesive Antibacterial Biofilm Orthodontics Remineralization White spot lesion ABSTRACT Objectives: To evaluate the bonding performance, antibacterial activity, and remineralization effect on enamel of the orthodontic adhesive containing MAE-DB and NACP. Methods: Eighty non-carious human premolars were divided into 3 groups: Transbond XT (TB), PEHB + 5% MAE-DB (PD), and PEHB + 40% NACP + 5% MAE-DB (PND). Premolars were bonded with orthodontic brackets, the first subgroup (n = 10) and the second subgroup (n = 10) were subjected to shear bond strength testing after immersed in water for 1 day and in demineralization solution for 28 days respectively and then tested surface roughness, while the third subgroup (n = 6) was used for microhardness evaluation after aged in demineralization solution for 28 days. For each adhesive, fifty disk samples were prepared for antibacterial study. Specimens measuring 12 mm × 2 mm × 2 mm were fabricated for ion release test. Results: Bond strengths were in the order TB = PND > PND = PD for “1-day in water”, and in the order TB = PND > PD for “28-days in pH 4 solution”. No significant difference in the ARI scores for the three adhesive. Numerous bacteria adhered to TB surface, while PD and PND had minimal bacterial growth and activity. PND showed high levels of Ca and P ions release and enamel hardness. The surface roughness of enamel in PND was much lower than TB and PD and showed no significant difference with the sound, control enamel. Conclusion: PND adhesive with 5% MAE-DB and 40% NACP exhibits antibacterial and remineralizing cap- abilities, and did not adversely affect bond strength compared to commercial adhesive. Clinical significance: Novel adhesive containing quaternary ammonium monomer and nano-amorphous calcium phosphate represents a promising candidate in combating enamel white spot lesions and even dental caries. 1. Introduction Formation of enamel white spot lesions around bonded orthodontic brackets is a serious and common complication during orthodontic treatment [1–3]. The prevalence of white spot lesions in patients with fixed appliance therapy has been reported to be 73–95% [2,4]. Previous studies have shown that the rate of enamel demineralization in orthodontic patients is higher than those without orthodontic treatment [5–7]. Placement of fixed appliances increases plaque accumulation around the brackets and colonization of cariogenic bacteria [4,8,9]. Organic acids produced by those bacteria such as lactic, propionic and butyric acids result in surface and subsurface demineralization of the tooth enamel [10]. Because of the esthetic concerns associated with peri-bracket white https://doi.org/10.1016/j.jdent.2018.03.004 Received 26 January 2018; Received in revised form 8 March 2018; Accepted 9 March 2018 ⁎ Corresponding authors at: State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi’an, China. ⁎⁎ Corresponding author at: State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi’an, 710032, China. 1 These authors contributed equally to this work. E-mail addresses: ftay@augusta.edu (F.R. Tay), jhchen@fmmu.edu.cn (J.-h. Chen). Journal of Dentistry xxx (xxxx) xxx–xxx 0300-5712/ © 2018 Elsevier Ltd. All rights reserved. Please cite this article as: Liu, Y., Journal of Dentistry (2018), https://doi.org/10.1016/j.jdent.2018.03.004