Please cite this article in press as: Ginjupalli K, et al. Does the size matter? Evaluation of effect of incorporation of silver nanoparticles of varying particle size on the antimicrobial activity and properties of irreversible hydrocolloid impression material. Dent Mater (2018), https://doi.org/10.1016/j.dental.2018.03.016 ARTICLE IN PRESS DENTAL-3134; No. of Pages 8 d e n t a l m a t e r i a l s x x x ( 2 0 1 8 ) xxx.e1–xxx.e8 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/dema Does the size matter? Evaluation of effect of incorporation of silver nanoparticles of varying particle size on the antimicrobial activity and properties of irreversible hydrocolloid impression material Kishore Ginjupalli a,∗ , Tushar Shaw b , Chaitanya Tellapragada c , Ramakrishna Alla d , Lokendra Gupta e , Nagaraja Upadhya Perampalli f a Department of Dental Materials, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India b Department of Microbiology, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India c Manipal Center for Virus Research, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India d Department of Dental Materials, Vishnu Dental College, Bhimavaram, 534202, Andhra Pradesh, India e Department of Prosthodontics and Crown and Bridge, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India f Department of Dental Materials, Manipal College of Dental Sciences, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India a r t i c l e i n f o Article history: Received 3 August 2017 Received in revised form 19 January 2018 Accepted 23 March 2018 Available online xxx Keywords: Alginate Antimicrobial activity Disinfection Infection control Irreversible hydrocolloid Silver nanoparticles a b s t r a c t Objectives. The main objective of the present in vitro study is to evaluate the antimicrobial activity and properties of irreversible hydrocolloid impression material incorporated with silver nanoparticles of varying size at different concentrations. Methods. Silver nanoparticles of 80–100, 50–80, 30–50 and 10–20 nm size were added to irre- versible hydrocolloid impression material at 0.5, 1.0, 2.0 and 5.0 wt%. Antimicrobial activity of the silver nanoparticle incorporated irreversible hydrocolloid was measured using disk diffusion method. The gel strength, flow, gelation time and permanent deformation were measured according to American Dental Association specification #18. Data were analyzed using analysis of variation at a confidence interval of 95% (˛ = 0.05). Results. Silver nanoparticles of 80–100 nm size have imparted superior antimicrobial activity to the irreversible hydrocolloid in a dose-dependent manner whereas finer nanoparticle size did not exhibit any antimicrobial activity. The addition of silver nanoparticles did not alter the properties of irreversible hydrocolloid at 0.5 and 1.0 wt% whereas at higher concentrations significant differences in flow, gelation time and strength were observed. ∗ Corresponding author. E-mail address: kishore.gp@manipal.edu (K. Ginjupalli). https://doi.org/10.1016/j.dental.2018.03.016 0109-5641/© 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.