Jegdish Babu

Chitosan coatings deliver antimicrobials from titanium implants: a preliminary study.

Objective:Chitosan was investigated as a coating for local delivery of antimicrobials for prevention of acute implant infection. The objectives of this study were to (1) measure the release of 2 antimicrobials from chitosan coatings, (2) determine efficacy of eluted antimicrobials against bacteria, in vitro, and (3) evaluate toxicity of eluted drugs to host cells/tissues. Methods:Chitosan coatings (80.7% deacetylated, 108 kDa) containing 20% tetracycline or 0.02% chlorhexidine digluconate were bonded to titanium via silane reactions. After elution in culture medium for 7 days, eluates were tested against model pathogens Actinobacillus actinomycetemcomitans and Staphylococcus epidermidis in turbidity tests and in 24-hour cytotoxicity tests using human osteoblasts and fibroblasts. Finally, antibiotic-loaded chitosan-coated titanium pins were implanted for 7 days in muscle of Sprague-Dawley rats to evaluate the initial tissue response. Results:Coatings released 89% of tetracycline in 7 days and 100% chlorhexidine in 2 days. Released tetracycline inhibited growth (95%–99.9%) of pathogens for up to 7 days with no cytotoxicity to human cells. Released chlorhexidine was active against pathogens for 1 to 2 days (56%–99.5% inhibition) but was toxic to cells on the first day of elution. Typical acute inflammatory response was observed to antimicrobial-loaded chitosan coatings similar to unloaded coatings. Conclusion:These preliminary data support the hypothesis that chitosan coatings have the potential to locally deliver antimicrobials to inhibit bacteria without being toxic to host cells/tissues and warrant additional studies to evaluate the ability of the coatings to prevent/resist infection and promote osseointegration.

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.

Inhibitory effects of a cured antibacterial bonding system on viability and metabolic activity of oral bacteria.

OBJECTIVES To evaluate the antimicrobial efficacy of Clearfil SE Protect (CP) and Clearfil SE Bond (CB) after curing and rinsed against five individual oral microorganisms as well as a mixture of bacterial culture prepared from the selected test organisms. METHODS Bacterial suspensions were prepared from single species of Streptococcus mutans, Streptococcus sobrinus, Streptococcus gordonii, Actinomyces viscosus and Lactobacillus lactis, as well as mixed bacterial suspensions from these organisms. Dentin bonding system discs (6 mm×2 mm) were prepared, cured, washed and placed on the bacterial suspension of single species or multispecies bacteria for 15, 30 and 60 min. MTT, Live/Dead bacterial viability (antibacterial effect), and XTT (metabolic activity) assays were used to test the two dentin systems antibacterial effect. All assays were done in triplicates and each experiment repeated at least three times. Data were submitted to ANOVA and Scheffes f-test (5%). RESULTS Greater than 40% bacteria killing was seen within 15 min, and the killing progressed with increasing time of incubation with CP discs. However, a longer (60 min) period of incubation was required by CP to achieve similar antimicrobial effect against mixed bacterial suspension. CB had no significant effect on the viability or metabolic activity of the test microorganisms when compared to the control bacterial culture. CP was significantly effective in reducing the viability and metabolic activity of the test organisms. SIGNIFICANCE The results demonstrated the antimicrobial efficacy of CP both on single and multispecies bacterial culture. CP may be beneficial in reducing bacterial infections in cavity preparations in clinical dentistry.

Assessment of the effect of chemical agents used in dentistry on the removal of Porphyromonas gingivalis and escherichia coli from sandblasted acid-etched titanium dental implants: An in vitro study

PURPOSE The aim of this study was to evaluate the capability of chemicals to decontaminate Escherichia coli (E coli) or Porphyromonas gingivalis (P gingivalis) from sandblasted acid-etched (SAE) titanium dental implants. MATERIALS AND METHODS SAE titanium dental implants were contaminated with E coli or P gingivalis and incubated in a sterile bacterial culture media under aerobic and anaerobic conditions, respectively. The implants were treated with 10 different conditions: calcium hydroxide [Ca(OH)₂] paste for 1 minute and saline irrigation for 1 minute; Ca(OH)2 paste for 1 minute and 0.2% chlorhexidine digluconate (CHXD) irrigation for 1 minute; 0.2% CHXD for 1 minute; Dakins solution for 1 minute; tetracycline hydrochloride (T-HCl) as a 1 g per 20 mL solution for 1, 2, and 3 minutes; and T-HCl paste for 1, 2, and 3 minutes. All implants were irrigated with 1 mL of saline solution and incubated under aerobic and anaerobic conditions for 24 hours or 48 hours for E coli- and P gingivalis-contaminated implants, respectively. The control group was submitted to all procedures except for the chemical treatments. Aliquots were removed, and turbidity was measured by spectrophotometry. The level of bacterial growth in control cultures was considered to have a decontamination percentage (DC%) of 0. RESULTS Spectrophotometric analysis showed that all chemical treatments resulted in significantly higher DC% compared to controls for SAE implants contaminated with E coli (P < .05) or P gingivalis (P < .05). For the P gingivalis experiments, SAE implants treated with Ca(OH)₂ paste and saline solution had a lower DC% (39.3%) than those in the other treatment groups. In the E coli experiments, DC% was significantly lower for SAE implants treated with Ca(OH)₂ paste and saline solution (48.7%), Dakins solution (92.7%), or T-HCl paste for 1 minute (96.6%) than those in the other groups. CONCLUSION The DC% of SAE implants contaminated with E coli or P gingivalis by means of chemicals commonly used in dentistry is high, with the exception of Ca(OH)₂ paste burnished for 1 minute and then irrigated with saline solution for 1 minute.

Efficiency of Nanotube Surface-Treated Dental Implants Loaded with Doxycycline on Growth Reduction of Porphyromonas gingivalis

PURPOSE The prevalence of peri-implant infection in patients with dental implants has been shown to range from 28% to 56%. A nanotube-modified implant surface can deliver antibiotics locally and suppress periodontal pathogenic bacterial growth. The aim of this study was to evaluate the deliverability of antibiotics via a nanotube-modified implant. MATERIALS AND METHODS Dental implants with a nanotube surface were fabricated and loaded with doxycycline. Afterward, each dental implant with a nanotube surface was placed into 2-mL tubes, removed from solution, and placed in a fresh solution daily for 28 days. Experimental samples from 1, 2, 4, 16, 24, and 28 days were used for this evaluation. The concentration of doxycycline was measured using spectrophotometric analysis at 273-nm absorbance. The antibacterial effect of doxycycline was evaluated by supplementing Porphyromonas gingivalis (P gingivalis) growth media with the solution collected from the dental implants at the aforementioned time intervals for a period of 48 hours under anaerobic conditions. A bacterial viability assay was used to evaluate P gingivalis growth at 550-nm absorbance. RESULTS Doxycycline concentration varied from 0.33 to 1.22 μg/mL from day 1 to day 28, respectively. A bacterial viability assay showed the highest P gingivalis growth at day 1 (2 nm) and the lowest at day 4 (0.17 nm), with a gradual reduction from day 1 to day 4 of approximately 87.5%. The subsequent growth pattern was maintained and slightly increased from baseline in approximately 48.3% from day 1 to day 24. The final P gingivalis growth measured at day 28 was 29.4% less than the baseline growth. CONCLUSION P gingivalis growth was suppressed in media supplemented with solution collected from dental implants with a nanotube surface loaded with doxycycline during a 28-day time interval.

Assessment of the Effect of CO2 Laser Irradiation on the Reduction of Bacteria Seeded on Commercially Available Sandblasted Acid-Etched Titanium Dental Implants: An In Vitro Study.

PURPOSE To evaluate the capability of carbon dioxide (CO₂) laser in reducing Escherichia coli on sandblasted acid-etched (SAE) titanium dental implants. MATERIALS AND METHODS SAE dental implants were contaminated with E coli, incubated in a sterile bacterial culture medium for 24 hours, and then exposed to CO₂ laser (10,600-nm wavelength) in superpulsed waves (SPW) at 1.5, 1.7, and 2 W at 100-Hz frequency and continuous wave (CW) at 1.5, 2, and 2.5 W. The presence of bacteria trapped in the implant surfaces after contamination and decontamination was verified using spectrophotometry. Scanning electron microscopy (SEM) was used to evaluate the topography of laser irradiation. After implant surface contamination was verified, implants were exposed to CO₂ laser irradiation, and bacterial growth was measured with spectrophotometry. RESULTS The control implants showed the highest bacterial growth (100% growth). Implants exposed to laser showed progressive increase in the percentage of decontamination (DC%) corresponding to the higher wattage in the SPW and CW groups. The DC% were 20.4%, 49.6%, and 51.7% in the SPW group at 100 Hz, at 1.5, 1.7, and 2 W of power, respectively. In the CW group, the DC% were 34.3%, 69.9%, and 85.5% at 1.7, 2, and 2.5 W, respectively. Kruskal-Wallis statistical analysis showed a significant difference between the groups (P < .05). In the pulsed mode (100-Hz) group, statistical analysis showed that the DC% of 1.5 W was significantly lower than the 2 W power. In the CW group, statistical analysis showed that the DC% at 1.7 W was significantly lower (P < .05) than with the other treatments. SEM assessment showed craterlike wear damages and accretions to the implant surfaces that increased progressively as the laser wattage increased. CONCLUSION CO₂ laser irradiation failed to completely decontaminate the implant surfaces. SEM analysis demonstrated damage to the top of the dental implant threads at all settings studied. Thus, CO₂ laser irradiation may not be the optimal method to decontaminate implants.

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 trimethylsilane plasma coating on the hydrophobicity of denture base resin and adhesion of Candida albicans on resin surfaces

Statement of problem Candida‐associated denture stomatitis is the most common oral mucosal lesion among denture wearers. Trimethylsilane (TMS) plasma coating may inhibit the growth of Candida albicans on denture surfaces. Purpose The purpose of this in vitro study was to investigate whether TMS plasma coatings can effectively reduce C albicans adhesion on denture base acrylic resin surfaces. Material and methods Sixty denture base acrylic resin disks with smooth and rough surfaces were prepared and were either left untreated (control group) or coated with TMS monomer (experimental group) by using plasma. Contact angles were measured immediately after TMS plasma coating. The morphology of C albicans adhesion was observed with scanning electron microscopy (SEM). Energy‐dispersive spectroscopy (EDS) was used to characterize the elemental composition of the specimen surface. An adhesion test was performed by incubating the resin disk specimens in C albicans suspensions (1×107 cells/mL) at 37°C for 24 hours and further measuring the optical density of the C albicans by using a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay test. One‐way ANOVA and 2‐way ANOVA were followed by a post hoc test analysis (&agr;=.05). Results The group with TMS coating exhibited a more hydrophobic surface than the control group. EDS analysis revealed successful TMS plasma coating. The difference in the mean contact angles between the uncoated group and the TMS‐coated group was statistically significant (P<.05), 79.0 ±2.9 degrees versus 105.7 ±1.5 degrees for the smooth surface and 90.2 ±7.6 degrees versus 131.5 ±2.1 degrees for the rough surface. In SEM analysis, the C albicans biofilm was found to grow more on the surface of the denture base resin without the TMS coating than on the surfaces of the experimental group. In the adhesion test, the amount of C albicans adhering to the surface of denture base resin with the TMS coating was significantly less than that on the surfaces without TMS coating (P<.05). Conclusions TMS coating significantly reduced the adhesion of C albicans to the denture base resin and may reduce denture stomatitis.