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Implant-related infections from the adhesion and proliferation of dental plaque are a major challenge for dental implants. The objectives of this study were to: (1) develop novel antibacterial titanium (Ti) healing abutment; (2) investigate the inhibition of implant infection-related pathogenic bacteria and saliva-derived biofilm, and evaluate the biocompatibility of the new material for the first time. Dimethylaminohexadecyl methacrylate (DMAHDM) and hydroxyapatite (HAP) were polymerized via polydopamine (PDA) on Ti. Staphylococcus aureus (S. aureus), Streptococcus sanguinis (S. sanguinis) and human saliva-derived biofilms were tested. After 4 weeks of DMAHDM release, the antibacterial efficacy of the DMAHDM remaining on Ti surface and the DMADHM in medium was tested. Biocompatibility was determined using human gingival fibroblasts (HGFs) and periodontal ligament stem cells (PDLSCs). The DMAHDM-loaded coating filled into the nano-voids in Ti surfaces. The modified Ti showed potent antibacterial activity, reducing the CFU of S. aureus , S. sanguinis and saliva-derived biofilms by 8, 7 and 4 log, respectively (P < 0.05). After 4 weeks of release, the modified Ti was still able to reduce S. aureus and S. sanguinis biofilm CFU by 1–3 log (P < 0.05). This provided strong antibacterial function for more than 4 weeks, which were the high-risk period for implant infections. The new material showed excellent biocompatibility when compared to control (P > 0.05). Novel DMAHDM-loaded Ti healing abutment had strong antibacterial effects, reducing biofilm CFUs by orders of magnitude, and lasting for over four weeks to cover the high-risk period for implant infections. The novel antibacterial Ti is promising to combat implant-related infections in dental, craniofacial and orthopedic applications. • The DMAHDM-loaded Ti effectively inhibit biofilms on the surface in the high-risk period of peri-implant inflammation. • The released DMAHDM inhibited the surrounding planktonic S. aureus and S. sanguinis. • After 4 weeks, the modified Ti was still able to show antibacterial effects on S. aureus and S. sanguinis biofilm. • The DMAHDM-loaded Ti is biocompatible, with no cytotoxicity to soft tissue seal and osseointegration related cells. [ABSTRACT FROM AUTHOR]

Dental caries is caused by acids from biofilms. pH-sensitive nanoparticle carriers could achieve improved targeted effectiveness. The objectives of this study were to develop novel mesoporous silica nanoparticles carrying nanosilver and chlorhexidine (nMS-nAg-Chx), and investigate the inhibition of biofilms as well as the modulation of biofilm to suppress acidogenic and promote benign species for the first time. nMS-nAg was synthesized via a modified sol-gel method. Carboxylate group functionalized nMS-nAg (COOH-nMS-nAg) was prepared and Chx was added via electrostatic interaction. Minimal inhibitory concentration (MIC), inhibition zone, and growth curves were evaluated. Streptococcus mutans (S. mutans), Streptococcus gordonii (S. gordonii), and Streptococcus sanguinis (S. sanguinis) formed multispecies biofilms. Metabolic activity, biofilm lactic acid, exopolysaccharides (EPS), and TaqMan real-time polymerase chain reaction (RT-PCR) were tested. Biofilm structures and biomass were observed by scanning electron microscopy (SEM) and live/dead bacteria staining. nMS-nAg-Chx possessed pH-responsive properties, where Chx release increased at lower pH. nMS-nAg-Chx showed good biocompatibility. nMS-nAg-Chx exhibited a strong antibacterial function, reducing biofilm metabolic activity and lactic acid as compared to control (p < 0.05, n = 6). Moreso, biofilm biomass was dramatically suppressed in nMS-nAg-Chx groups. In control group, there was an increasing trend of S. mutans proportion in the multispecies biofilm, with S. mutans reaching 89.1% at 72 h. In sharp contrast, in nMS-nAg-Chx group of 25 μg/mL, the ratio of S. mutans dropped to 43.7% and the proportion of S. gordonii and S. sanguinis increased from 19.8% and 10.9 to 69.8% and 56.3%, correspondingly. pH-sensitive nMS-nAg-Chx had potent antibacterial effects and modulated biofilm toward a non-cariogenic tendency, decreasing the cariogenic species nearly halved and increasing the benign species approximately twofold. nMS-nAg-Chx is promising for applications in mouth rinse and endodontic irrigants, and as fillers in resins to prevent caries. [Display omitted] [ABSTRACT FROM AUTHOR]