Antibacterial properties of silver-loaded gelatin sponges prepared with silver diamine fluoride.

PURPOSE: To evaluate the antibacterial efficiency of silver-loaded gelatin sponges prepared from gelatin and silver diamine fluoride, Ag(NH3)2F. METHODS: A series of novel silver-loaded gelatin sponges were prepared from gelatin and silver diamine fluoride. They were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The antibacterial activities against one oral bacteria model S. mutans were evaluated using the agar disk diffusion method and biofilm-grown bacteria assay. For the purpose of comparison, a second series of silver-loaded sponges were prepared using silver nitrate (AgNO3) as the silver source. RESULTS: FT-IR, SEM and EDX results confirmed the successful preparation of silver-loaded gelatin sponges from both silver diamine fluoride and silver nitrate. Agar disk diffusion assays revealed that the antibacterial activity of silver-loaded sponges was strongly correlated with the silver content, and also depending on the silver source used in the preparation of sponges. Sustained inhibition of S. mutans in agar plates was observed for silver-loaded gelatin sponges containing about 5 wt% Ag or more. Biofilm assays showed different viabilities when treated with different formulations, with the viability of 11.4±3.1% for the sponges containing 5.30±1.18 wt% Ag prepared from silver diamine fluoride, and the viability of 15.4±3.1% for the sponges containing 29.13±10.34 wt% Ag prepared from silver nitrate. CLINICAL SIGNIFICANCE: The silver loading contents had a significant effect on the antibacterial activities of silver-loaded gelatin sponges prepared with silver diamine fluoride. In addition, silver diamine fluoride was a superior silver source to prepare antibacterial silver-loaded gelatin sponges when compared with silver nitrate.

Modified Polymeric Nanoparticles Exert In Vitro Antimicrobial Activity Against Oral Bacteria.

Polymeric nanoparticles were modified to exert antimicrobial activity against oral bacteria. Nanoparticles were loaded with calcium, zinc and doxycycline. Ions and doxycycline release were measured by inductively coupled plasma optical emission spectrometer and high performance liquid chromatography. Porphyromonas gingivalis, Lactobacillus lactis, Streptoccocus mutans, gordonii and sobrinus were grown and the number of bacteria was determined by optical density. Nanoparticles were suspended in phosphate-buffered saline (PBS) at 10, 1 and 0.1 mg/mL and incubated with 1.0 mL of each bacterial suspension for 3, 12, and 24 h. The bacterial viability was assessed by determining their ability to cleave the tetrazolium salt to a formazan dye. Data were analyzed by ANOVA and Scheffe’s F (p < 0.05). Doxycycline doping efficacy was 70%. A burst liberation effect was produced during the first 7 days. After 21 days, a sustained release above 6 µg/mL, was observed. Calcium and zinc liberation were about 1 and 0.02 µg/mL respectively. The most effective antibacterial material was found to be the Dox-Nanoparticles (60% to 99% reduction) followed by Ca-Nanoparticles or Zn-Nanoparticles (30% to 70% reduction) and finally the non-doped nanoparticles (7% to 35% reduction). P. gingivalis, S. mutans and L. lactis were the most susceptible bacteria, being S. gordonii and S. sobrinus the most resistant to the tested nanoparticles.

Effects of atmospheric non-thermal argon/oxygen plasma on biofilm viability and hydrophobicity of oral bacteria.

PURPOSE: To evaluate the bactericidal effects of atmospheric non-thermal argon/oxygen plasma on in vitro oral biofilms constructed from S. mutans and/or S. sanguinis, and the influence of the plasma on the virulence properties of A. oris. METHODS: In vitro oral biofilms were constructed in the wells of 48-well plates from S. mutans and/or S. sanguinis. The wells containing constructed biofilms and various amounts of phosphate-buffered saline (PBS) were treated with non-thermal argon/oxygen plasma brush for 2 minutes. The methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and Live/Dead assay were used to evaluate the viability of biofilms in those wells after the plasma treatments. Meanwhile, A. oris suspensions were treated with the plasma and then evaluated for their virulence properties by measuring the hydrophobicity and co-aggregation capability of treated A. oris. RESULTS: The MTT assay showed that exposure to non-thermal plasma for 2 minutes significantly reduced the viability of bacteria in both single-species and two-species biofilms of S. mutans and S. sanguinis with the reductions of up to 99%. Meanwhile, plasma treatment also altered the hydrophobicity of A. oris, and reduced their capability to co-aggregate with S. sanguinis. CLINICAL SIGNIFICANCE: The results from this study demonstrated that atmospheric non-thermal argon/oxygen plasma could effectively deactivate oral bacteria biofilm by decreasing bacterial viability as well as reducing their hydrophobicity and co-aggregation capability.

Efficacy of 4 Irrigation Protocols in Killing Bacteria Colonized in Dentinal Tubules Examined by a Novel Confocal Laser Scanning Microscope Analysis.

INTRODUCTION: The aim of this study was to determine the efficiency of 4 irrigation systems in eliminating bacteria in root canals, particularly in dentinal tubules. METHODS: Roots of human teeth were prepared to 25/04, autoclaved, and inoculated with Enterococcus faecalis for 3 weeks. Canals were then disinfected by (1) standard needle irrigation, (2) sonically agitating with EndoActivator, (3) XP Endo finisher, or (4) erbium:yttrium aluminum garnet laser (PIPS) (15 roots/group). The bacterial reduction in the canal was determined by MTT assays. For measuring live versus dead bacteria in the dentinal tubules (4 teeth/group), teeth were split open and stained with LIVE/DEAD BackLight. Coronal, middle, and apical thirds of the canal dentin were scanned by using a confocal laser scanning microscope (CLSM) to determine the ratio of dead/total bacteria in the dentinal tubules at various depths. RESULTS: All 4 irrigation protocols significantly eliminated bacteria in the canal, ranging from 89.6% to 98.2% reduction (P < .001). XP Endo had the greatest bacterial reduction compared with other 3 techniques (P < .05). CLSM analysis showed that XP Endo had the highest level of dead bacteria in the coronal, middle, and apical segments at 50-µm depth. On the other hand, PIPS had the greatest bacterial killing efficiency at the 150-µm depth in all 3 root segments. CONCLUSIONS: XP Endo appears to be more efficient than other 3 techniques in disinfecting the main canal space and up to 50 µm deep into the dentinal tubules. PIPS appears to be most effective in killing the bacteria deep in the dentinal tubules.

In vitro comparison of commercial oral rinses on bacterial adhesion and their detachment from biofilm formed on hydroxyapatite disks.

PURPOSE: This in vitro study was designed to assess the effectiveness of three oral rinses on bacterial adherence to epithelial cells and hydroxyapatite surfaces. The role of oral rinses on the detachment of bacteria from biofilm was also evaluated. MATERIALS AND METHODS: The efficacy of three oral rinses, Acclean, Noplak and Prevention were tested against a wide range of oral bacteria. Oral rinse antimicrobial activity was determined by an MTT assay for bacterial viability, by live/ dead staining and by measuring the bacterial metabolic activity using an XTT assay. RESULTS: The two oral rinses that contained 0.12% chlorhexidine had the greatest antibacterial activity on both planktonic and bio lm-grown organisms when compared to the Prevention oral rinse. CONCLUSION: Both Acclean and Noplak were extremely effective in lowering the number of bacteria attached to buccal epithelial cells and pelllicles. In addition, these two oral rinses were also effective against the biofilm bacteria.