Silver(I) metal complexes with bioactive ligands with potential use as intracanal medication: antimicrobial activity and effects on the biology of human apical papilla cells

• Grant number: 24/15905-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: July 01, 2025
• End date: February 28, 2026
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Gisele Faria
• Grantee: Breno Henrique Amancio
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Regenerative endodontic procedures (REP) aim to promote the completion of root formation in teeth with incomplete rhizogenesis and pulp necrosis, a process that depends mainly on the cells of the apical papilla. Infection control through intracanal medication (ICM) is crucial for the differentiation of mesenchymal stem cells of the apical papilla into cells that produce dental tissue. The most used ICMs in REPs are antibiotic pastes and calcium hydroxide. However, both have disadvantages, and in the case of antibiotic pastes, the main one is the potential to induce the development of bacterial resistance. Therefore, new ICMs capable of controlling endodontic infection with greater effectiveness, with minimal potential to induce the development of bacterial resistance, reduced adverse effects, and that are biocompatible with the cells of the apical papilla are of great importance. The combination of silver ions with biologically active ligands [silver(I) complexes] has been considered as a strategy to develop promising antimicrobial agents. Silver(I) complexes with probenecid, furosemide or 4-aminobenzoic acid ligands (Ag-PROB, Ag-FSE and Ag-pABA, respectively) have potential to be used as MICs due to their antimicrobial activity, biocompatibility, stability and lack of mutagenicity induction. However, in order for them to be delivered to the root canal, they must be associated with a sustained release system. The aim of this study will be to evaluate the activity of silver(I) complexes Ag-PROB, Ag-FSE and Ag-pABA on microorganisms associated with endodontic infection, the sustained release of the complexes associated with bacterial cellulose spheres (BCS), as well as when associated with macrogol + propylene glycol ointment (macro/propi), and their effects on human apical papilla cells (hAPCs). Triple antibiotic paste will be used as control. The antimicrobial activity of Ag-PROB, Ag-FSE and Ag-pABA complexes will be evaluated by determining the minimum inhibitory concentration (MIC) for Candida albicans and Enterococcus faecalis strains and by analyzing their effects on the biofilm biomass of these microorganisms, using the crystal violet assay. The sustained release capacity of the complexes associated with ECB will be evaluated by agar diffusion and release kinetics in Franz cells, and the release of the macro/propi complexes by agar diffusion. The effects of the complexes on hAPCs will be evaluated based on three criteria: cell viability, using the methylthiazole tetrazolium (MTT) and neutral red assays; alkaline phosphatase activity, measured by thymolphthalein release; and production of mineralized nodules, analyzed by alizarin red staining. Statistical tests will be chosen according to the distribution and homoscedasticity of the data, using a significance level of 5%.