Biodegradable nanofibrous drug delivery systems: effects of metronidazole and ciprofloxacin on periodontopathogens and commensal oral bacteria.

OBJECTIVES: The purposes of this study were to fabricate biodegradable polydioxanone (PDS II®) electrospun periodontal drug delivery systems (hereafter referred to as matrices) containing either metronidazole (MET) or ciprofloxacin (CIP) and to investigate the effects of antibiotic incorporation on both periodontopathogens and commensal oral bacteria. MATERIALS AND METHODS: Fibrous matrices were processed from PDS polymer solution by electrospinning. Antibiotic-containing PDS solutions were prepared to obtain four distinct groups: 5 wt.% MET, 25 wt.% MET, 5 wt.% CIP, and 25 wt.% CIP. Pure PDS was used as a control. High-performance liquid chromatography (HPLC) was done to evaluate MET and CIP release. Dual-species biofilms formed by Lactobacillus casei (Lc) and Streptococcus salivarius (Ss) were grown on the surface of all electrospun matrices. After 4 days of biofilm growth, the viability of bacteria on biofilms was assessed. Additionally, antimicrobial properties were evaluated against periodontopathogens Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa) using agar diffusion assay. RESULTS: A three-dimensional interconnected porous network was observed in the different fabricated matrices. Pure PDS showed the highest fiber diameter mean (1,158 ± 402 nm) followed in a descending order by groups 5 wt.% MET (1,108 ± 383 nm), 25 wt.% MET (944 ± 392 nm), 5 wt.% CIP (871 ± 309 nm), and 25 wt.% CIP (765 ± 288 nm). HPLC demonstrated that groups containing higher amounts (25 wt.%) of incorporated drugs released more over time, while those with lower levels (5 wt.%) the least. No inhibitory effect of the tested antibiotics was detected on biofilm formation by the tested commensal oral bacteria. Meanwhile, CIP-containing matrices inhibited growth of Fn and Aa. CONCLUSION: CIP-containing matrices led to a significant inhibition of periodontopathogens without negatively impairing the growth of periodontal beneficial bacteria. CLINICAL RELEVANCE: Based on the proven in vitro inhibition of periodontitis-related bacteria, future in vivo research using relevant animal models is needed to confirm the effectiveness of these drug delivery systems.

The Effects of Plantago major on the Activation of the Neutrophil Respiratory Burst.

Plantago major is a common plant that grows worldwide in temperate zones and is found in fields, lawns, and on the roadsides. Its leaves and seeds have been used in almost all parts of the world for centuries as a wound healer, analgesic, antioxidant, and antibiotic, as well as an immune system modulator, antiviral, antifungal, and anti-inflammatory agent. Baicalein and aucubin are the two most biologically active components of P. major, and both have been shown to have antioxidant, anti-inflammatory, and anticancer properties. Neutrophils have a pivotal role in wound healing and inflammation. Their principal mechanism of host defense is the killing of pathogens via the production of reactive oxygen species (ROS). The aim of the present study was to determine the in vitro effects of P. major extract, baicalein, and aucubin on human neutrophil respiratory burst activity. The cytotoxicity of the agents was assessed by lactate dehydrogenase (LDH) assays. A standard luminol-dependent chemiluminescence (CL) assay was utilized to monitor the respiratory burst of the neutrophils after exposure to P. major extract and its two active ingredients, baicalein and aucubin. Three replicates per group were included in each of the three runs of the experiments and analysis of variance (ANOVA) was used for statistical analysis. P. major and baicalein were not toxic to the cells at any of the concentrations examined. Aucubin was toxic to the cells only at the highest concentration tested (P = 0.0081). However, genistein was toxic to the cells at all of the concentrations examined except for the lowest concentration of 16.9 µg/ml (P = 0.985). P. major (-0.10 ± 0.11), aucubin (0.06 ± 0.16), baicalein (-0.10 ± 0.11), and genistein (-0.18 ± 0.07) all significantly (P < 0.0001) inhibited ROS production from the neutrophils. P. major extract inhibited neutrophil ROS production, as did aucubin and baicalein. Therefore, these components should be investigated further with relation to the regulation of destructive ROS production in conditions such as periodontal disease.

Using the patient's medication history as a learning tool in clinical pharmacology instruction for dental students.

The purpose of this study was to determine if a pharmacology medical history assignment would enable dental students to demonstrate improved knowledge and understanding of pharmacology by researching the drugs their patients were taking and recording pharmacological information in their patients' health records. The study followed a pretest-posttest design and evaluated students' knowledge of ten commonly prescribed drugs. Students were given the pretest prior to entry into the clinic. Subsequently, for an eight-month period, students completed the medication history assignment. Pretest and posttest scores were compared and analyzed with one-way ANOVA and Pearson product moment correlation statistics. The Pearson product moment correlation showed a positive correlation between the drugs per patient and the change in score between the pre- and posttests (correlation coefficient=0.254, p=0.016) and between the assignment grade and the change in pre- and posttest scores (correlation coefficient=0.198, p<0.001), as well as a significant correlation between the number of times a drug was charted and the change in score on the pretest-posttest item concerning that drug (correlation coefficient=0.798, p=0.006). By documenting patient drug information, dental students can improve their pharmacology knowledge base and enhance their potential to positively impact patient care and safety.

Effects of Calendula officinalis on human gingival fibroblasts.

BACKGROUND: Calendula officinalis is commonly called the marigold. It is a staple topical remedy in homeopathic medicine. It is rich in quercetin, carotenoids, lutein, lycopene, rutin, ubiquinone, xanthophylls, and other anti-oxidants. It has anti-inflammatory properties. Quercetin, one of the active components in Calendula, has been shown to inhibit recombinant human matrix metalloproteinase (MMP) activity and decrease the expression of tumor necrosis factor-α, interleukin-1ß (IL), IL-6 and IL-8 in phorbol 12-myristate 13-acetate and calcium ionophore-stimulated human mast cells. OBJECTIVES: To examine the effects of Calendula on human gingival fibroblast (HGF) mediated collagen degradation and MMP activity. MATERIAL AND METHODS: Lactate dehydrogenate assays were performed to determine the non-toxic concentrations of Calendula, doxycycline and quercetin. Cell-mediated collagen degradation assays were performed to examine the inhibitory effect on cell-mediated collagen degradation. Gelatin zymography was performed to examine their effects on MMP-2 activity. The experiments were repeated three times and ANOVA used for statistical analyses. RESULTS: Calendula at 2-3% completely inhibited the MMP-2 activity in the zymograms. Doxycycline inhibited HGF-mediated collagen degradation at 0.005, 0.01, 0.02 and 0.05%, and MMP-2 activity completely at 0.05%. Quercetin inhibited HGF-mediated collagen degradation at 0.005, 0.01 and 0.02%, and MMP-2 activity in a dose-dependent manner. Calendula inhibited HGF-mediated collagen degradation and MMP-2 activity more than the same correlated concentration of pure quercetin. CONCLUSION: Calendula inhibits HGF-mediated collagen degradation and MMP-2 activity more than the corresponding concentration of quercetin. This may be attributed to additional components in Calendula other than quercetin.

The impact of three strains of oral bacteria on the surface and mechanical properties of a dental resin material.

The purpose of this study was to determine if three strains of bacteria could impact the mechanical or surface properties of a dental resin material. Resin material specimens were incubated at 37°C in sterile saline, tryptic soy broth supplemented with sucrose (TSBS), or TSBS inoculated with Streptococcus mutans, Streptococcus gordonii, or Streptococcus sanguis. The specimens were subjected to Fourier transform infrared spectroscopy before and after incubation. The flexural strength test was performed once a week for 6 weeks. Microhardness and scanning electron microscopy (SEM) was performed on specimens at 1 and 6 weeks. Differences in the area under the carbonyl peak were statistically significant for the specimens incubated in the media inoculated with either S. mutans or S. gordonii. To determine why S. sanguis did not produce changes as the other bacteria did, triethylene glycol dimethacrylate, methacrylic acid, and triethylene glycol were added to bacterial cultures at increasing concentrations. Both methacrylic acid and triethylene glycol reduced the number of colony-forming units of S. sanguis. Specimens incubated in TSBS, saline or in culture with S. sanguis demonstrated a decrease in peak stress in week 1 of the flexure strength test. SEM demonstrated that surface topology changed for those specimens incubated in culture with S. mutans or S. gordonii. The changes in surface topology demonstrated here could contribute to the secondary caries and changes in esthetic properties seen clinically with the use of resin materials in dental restorations.

Biodegradation of a dental resin material by fibroblast conditioned media.

OBJECTIVE: Hydrolytic activity is increased in conditioned media from human gingival and pulp fibroblasts in response to exposure to triethyleneglycol dimethacrylate (TEGDMA). The purpose of this study was to determine if this conditioned media with hydrolytic activity could cause the biodegradation of a dental resin material. METHODS: Resin material specimens were stored for 30 days at 37 degrees C in distilled water, unconditioned media, artificial serum, conditioned media from human gingival and pulp fibroblasts and conditioned media from human pulp and gingival fibroblasts that were exposed to TEGDMA. The media was exchanged every other day. The specimens were subjected to Fourier transform infrared spectroscopy (FTIR) before and after storage. The area under the carbonyl peak was calculated for all the specimens to determine the extent of the degradation. RESULTS: Differences before and after storage in the area under the carbonyl peak were statistically significant for the specimens stored in the conditioned media from the fibroblasts that were exposed to TEGDMA. All of the other specimens did not produce differences in the area under the carbonyl peak that were statistically significant when comparing the before and after storage results. SIGNIFICANCE: The biodegradation demonstrated here could contribute to the marginal leaking seen clinically with the use of resin materials in dental restorations.

In vitro induction of hydrolytic activity in human gingival and pulp fibroblasts by triethylene glycol dimethacrylate and monocyte chemotatic protein-1.

OBJECTIVE: Some dental resin composite materials leach the monomer triethylene glycol dimethacrylate (TEGDMA), which could contribute to the inflammatory reaction. The purpose of this study was to examine the ability of TEGDMA to alter cytokine/growth factor secretion and enzymatic activity in monocyte derived macrophages (U937 cells), human gingival fibroblasts (HGFs), and human pulp fibroblasts (DPFs). METHODS: A human growth factor/cytokine antibody array was utilized to determine whether TEGDMA alters the expression of cytokines/growth factors from U937 cells, HGFs, and DPFs. To determine if TEGDMA alters the hydrolase activity of U937, DPF, and HGF cells, the hydrolysis of p-nitrophenyl butyrate was utilized in a spectrophotometric assay. RESULTS: TEGDMA exposure induced the expression of monocyte chemotatic protein-1 (MCP-1) from the U937 cells. Both the cell lysates and conditioned media from the HGFs showed increased hydrolase activity after exposure to a sublethal concentration of TEGDMA. MCP-1 alone increased the hydrolytic activity and the combination of MCP-1 and TEGDMA was additive in HGF conditioned media. The DPFs were also exposed to MCP-1 alone and followed by a sublethal concentration of TEGDMA. The effect of MCP-1 was greater than that of TEGDMA. SIGNIFICANCE: These results demonstrate that TEGDMA induces enzymatic activity and cytokine/growth factor expression in a cell-specific manner.