Antibacterial and Cytocompatible: Combining Silver Nitrate with Strontium Acetate Increases the Therapeutic Window

Microbial infection and insufficient tissue formation are considered to be the two main causes of dental implant failure. Novel studies have focused on designing dual-functional strategies to promote antibacterial properties and improve tissue cell response simultaneously. In this study, we investigated the antibacterial properties and cytocompatibility of silver nitrate (AgNO3) and strontium acetate (SrAc) in a mono-culture setup for dental application. Additionally, we defined the therapeutic window between the minimum inhibitory concentration against pathogenic bacteria and maximum cytocompatible dose in the case of combined applications in a co-culture setup. Antibacterial properties were screened using Aggregatibacter actinomycetemcomitans and cell response experiments were performed with osteoblastic cells (MC3T3) and fibroblastic cells (NIH3T3). The osteoinductive behavior was investigated separately on MC3T3 cells using alizarin red staining. A therapeutic window for AgNO3 as well as SrAc applications could be defined in the case of MC3T3 cells while the cytocompatibility of NIH3T3 cells was compromised for all concentrations with an antibacterial effect. However, the combined application of AgNO3/SrAc caused an enhanced antibacterial effect and opened a therapeutic window for both cell lines. Enhanced mineralization rates could be observed in cultures containing SrAc. In conclusion, we were able to demonstrate that adding SrAc to AgNO3 not only intensifies antibacterial properties but also exhibits bone inductive characteristics, thereby offering a promising strategy to combat peri-implantitis and at the same time improve osseointegration in implant therapy.