Research Article EvaluationofAntibacterialEffectsofFissureSealantsContaining Chitosan Nanoparticles Sedighe Sadat Hashemi kamangar , 1 Houtan Zareian , 2 Abbas Bahador , 3 Maryam Pourhajibagher , 4 Zahra Bashareh, 2 and Sara Valizadeh 4,5 1 Department of Operative Dentistry, International Campus, Dental School, Tehran Universityof Medical Sciences, Tehran, Iran 2 International Campus, Dental School, Tehran University of Medical Sciences, Tehran, Iran 3 Department of Medical Microbiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran 4 Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran 5 Restorative Dentistry Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Correspondence should be addressed to Sara Valizadeh; valizadeh_s@sina.tums.ac.ir Received 5 April 2021; Accepted 7 August 2021; Published 17 August 2021 Academic Editor: Boonlert Kukiattrakoon Copyright © 2021 Sedighe Sadat Hashemi kamangar et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives. e present study evaluated the antimicrobial effects of fissure sealants containing chitosan nanoparticles. Materials and Methods. Antibacterial effect of Master Dent fissure sealant alone and after incorporating chitosan nanoparticles was evaluated on Streptococcus mutans, sanguis, and Lactobacillus acidophilus. Biofilm growth was evaluated by determining colony counts. Antimicrobial effect was determined on days 3, 15, and 30 by counting microbial colonies using eluted components test. One-way ANOVA, Tukey HSD tests, t test, and two-way ANOVA were used for statistical analyses (α � 0.05). Results. Biofilm inhibition test showed that fissure sealant containing 1 wt.% chitosan decreased colony counts significantly (P < 0.05). Eluted components test with S. mutans and sanguis showed significant decrease in colony counts during the first 15 days in chitosan containing group; however, from day 30, antimicrobial activity decreased noticeably, with no significant difference from control group (P > 0.05). Antimicrobial activity against L. acidophilus was maintained in chitosan group up to 30 days, and decrease in colony counts was significant (P < 0.05). Conclusion. According to the results of this study, incorporation of 1 wt.% chitosan into fissure sealant induced an antimicrobial activity. Antibacterial effect on L. acidophilus persisted for longer time (30 days) compared to the two other bacterial species (15 days). 1.Introduction Despite advances in identifying cariogenic factors and caries prevention techniques, dental caries is still an oral condition due to biofilms with a pandemic distribution pattern. e pits and fissures on the occlusal surfaces of permanent teeth with deep and narrow topography are considered a challenge for the mechanical cleaning of these areas [1]. erefore, these surfaces are very susceptible to the invasion of oral microflora and their metabolic byproducts. It has been re- ported that sealing pits and fissures can be a preventive measure against bacterial invasion by creating a physical protective barrier [2]. Previous studies have shown that resin-based sealers are better than other materials in terms of retention and sealing ability and can decrease the risk of new caries up to 18% in high-risk individuals. ey are superior to glass ionomer in terms of retention, with similar results in terms of pre- vention [3]. Although sealers are widely used to prevent dental caries, they exhibit a high failure rate. Bacterial colonization beneath the sealants and demineralization of teeth are among the important factors which are attributed to this issue [4, 5]. In vitro studies have shown that despite fissure sealants’ good sealing ability, microleakage is observed around them, especially after thermocycling, associated with the adhesion Hindawi International Journal of Dentistry Volume 2021, Article ID 8975948, 7 pages https://doi.org/10.1155/2021/8975948