Ag NPs are one of the most widely used dentistry restoration and dental implant doping choices due to their outstanding antimicrobial properties
[107]. Ag adheres to the bacterial cell wall and the cytoplasmic membrane electrostatically, which causes structural disruption
[106]. This results in extensive damage to bacterial DNA, proteins and lipids, resulting in the inhibition of bacterial growth/viability and effective bactericidal action. Besides, Ag NPs can also stimulate osteogenesis and soft-tissue integration, making them an ideal choice for dental implant surface modification
[108]. For instance, dental abutments modified with Ag NP suspension prevented
C. albicans contamination, in comparison with the controls of unmodified abutments
[109]. Further, citrate-capped Ag NPs offered bactericidal effects against
S. aureus and
P. aeruginosa [110]. Ti implants deposited with Ag NPs using anodic spark deposition have also been co-doped with Si, Ca, P and Na ions, to offer synergistic antibacterial (
S. epidermidis,
S. mutans and
E. coli) and osteogenic (human osteoblast-like cells, SAOS-2) functions
[111]. Similarly, to confirm that the used dosage of Ag NPs is safe, a culture of HGFs on Ag NPs/Ti was performed in vitro and the results confirmed no adverse effects
[112]. Further, Ag NPs have also been immobilized on Ti implants pre-modified with hydroxyapatite
[113], hydrogen titanate
[114], chitosan/hyaluronic acid multilayer
[115], nanoporous silica coatings
[116], Pt and Au
[117], and sandblasting and acid-etching
[118] in order to achieve superior antibacterial and bioactivity effects. However, while Ag NPs offer effective antimicrobial action, they may cause cytotoxicity via the release of free Ag+ ions, ROS production, transport across blood-brain-barrier, and inflammation
[106]. In a manner that is also applicable to other NPs discussed below, the toxicity of NPs depends on their chemical composition, surface charge, size and shape
[119]