Quaternary ammonium silane (k21) based intracanal medicament triggers biofilm destruction

(2021) 21:116 Kok et al. BMC Oral Health https://doi.org/10.1186/s12903-021-01470-x RESEARCH ARTICLE Open Access Quaternary ammonium silane (k21) based intracanal medicament triggers biofilm destruction Esther Sook Kuan Kok1, Xian Jin Lim1, Soo Xiong Chew1, Shu Fen Ong1, Lok Yin See1, Siao Hua Lim1, Ling Ang Wong1, Fabian Davamani2, Venkateshbabu Nagendrababu1,3, Amr Fawzy4 and Umer Daood1* Abstract Background: Compare antimicrobial efficacy of a quarternary ammonium silane (QAS)/k21 as an intracanal medicament against E. faecalis and C. albicans biofilms formed on root dentin. Methodology: Dentin blocks were sterilized and E. faecalis and C. albicans microbial colonies were counted for colony-forming-units against 2%k21, 2%CHX and Ca(OH)2 medicaments. Biofilm colonies after 7 days on dentin were analysed using confocal laser scanning microscopy with live/dead bacterial viability staining. TEM was done to study dentin collagen matrix. Dentin discs from 3rd day and 7th day well plate was used for Raman spectra and observed under fluorescent-microscope. Docking studies were carried out on MMP-2 S1 binding-domain with k21. Results: There was reduction of E. faecalis/C. albicans when k21, chlorhexidine and calcium hydroxide were used with highest percentage in 2%k21 treated specimens. 2%k21 showed dense and regular collagen network with intact cross-banding and decreased Raman intensity for 2%k21 on 3rd day. NaOCl + k21 showed least adherence, whereas saline groups showed highest adherence of E. faecalis and C. albicans to root-canal dentin. Alizarin red staining of hDPSCs revealed calcium deposition in all groups with significant difference seen amongst 2%k21 groups. MMP-2 ligand binding was seen accurately indicating possible target sites for k21 intervention. Conclusion: 2%k21 can be considered as alternative intracanal medicament. Keywords: Calcium hydroxide, Chlorhexidine, Dentine, Intracanal medicament, Quaternary ammonium silane Background There is acidic dissolution of dental hard tissues due to breach of microorganisms [1] through exposed dentinal tubules and cracks in teeth reaching the pulp space, leading to dental infections [2]. Poor disinfection procedures result in bacterial penetration within the root canal system leading to endodontic failures [3]. The use of voluminous irrigating solutions is considered pivotal for root *Correspondence: 1 Division of Clinical Dentistry, Schoolof Dentistry, International Medical University Kuala Lumpur, Kuala Lumpur, Malaysia Full list of author information is available at the end of the article canal therapy [4]. Hence the use of disinfectants becomes invaluable for the elimination of toxic microorganisms [5]. Proper disinfection helps in achieving predictable long-term outcome of root canal treatment [6]. There have been many approaches introduced to reduce the microorganism load in the root canal system, including instrumentation, root canal drug treatments (using irrigants and /or intracanal medicaments), root canal irrigation systems (e.g. ultrasonically activated irrigation, EndoVac) and root canal sealers [7–9]. Intracanal medicaments have contributed mainly towards root canal disinfection by promoting significant microbial reduction after chemo-mechanical procedures [10–13]. Hence the © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Kok et al. BMC Oral Health (2021) 21:116 intracanal medicament plays a key role in root canal treatment. Calcium hydroxide and chlorhexidine (CHX) are commonly used intracanal medicaments for root canal disinfection. Enterococcus faecalis is highly resistant and has a pivotal role in infections of root treated teeth leading to high rate of treatment failure [14]. E. faecalis is the most common microorganism present in persistent intraradicular infections compared with primary chronic periapical periodontitis [15]. Enterococcus faecalis has the ability to survive in high alkalinity and in presence of antimicrobial agents [16]. The antimicrobial agents used can only reduce E. faecalis but cannot remove all microbes colonized inside the root canal effectively [17]. Therefore, it is imperative to analyze different formulations with minimal toxic effects on periapical tissues and substantial antimicrobial potential. Candida occurs in small proportion of root canal infections with prevalence of 8.20%, possessing virulence factors that may play a role in the onset of endodontic pathologies [18, 19]. Therefore, it is critical to find new methods and antimicrobial agents for effective control of bacterial and fungal infections in root canal therapy. Several investigations have been conducted to determine the antimicrobial properties of dental materials. Polymeric and inorganic agents are capable of inhibiting microorganism proliferation [20]. Quaternary ammonium-based materials are used as antimicrobial agents showing its potential as new bioactive monomers. These materials exhibit excellent growth inhibitory effect against most microorganisms which is comparable to most antibiotics used [21]. In this study, a new class of Organosilane quaternary ammoniums (k21(QAS)); KHG FiteBac® Technology, GA, USA) was investigated containing one molecule of 3-(trimethoxysilyl) propyldimethyloctadecyl ammonium chloride (SiQAC) and three molecules of 3 methacryloxypropyltrimethoxysilane which were attached with a silane-based sol–gel route having an anchoring unit consisting of tetraethoxysilane [22]. The compound is a contact killing agent (kill-on-contact microbiocidal activities) possessing low cytotoxicity and broad-spectrum antimicrobial activities [23–26]. The antimicrobial property is derived from –C18H37 lipophilic alkyl chain which disturbs the bacterial membrane causing total cell autolysis. The binding of the quaternary ammonium compound is selective and towards the Sortase A protein within the bacterial membrane via electrostatic and hydrogen bonding coupled with van de (...truncated)