Journal of the California Dental Association, May 1, 2012
This study investigated sterilization of used implant impression copings and healing abutments. C... more This study investigated sterilization of used implant impression copings and healing abutments. Components were analyzed after contamination with Enterococcus foecalis, followed by multiple rounds of sterilization by both steam autoclave and Chemiclave protocols. The authors' results demonstrated that used components showed sterility equal to new components without any visible distortion. These data suggest that component resterilization and reuse may be justified or at least considered in clinical practice. Also, implications for cost savings in the placement of implants are advanced.
The Journal of Contemporary Dental Practice, Jan 7, 2012
AIM: To measure the time course hydrogen peroxide penetration into the pulp cavity and evaluate s... more AIM: To measure the time course hydrogen peroxide penetration into the pulp cavity and evaluate short-term tooth color changes after bleaching.MATERIALS AND METHODS: Twenty extracted human canines were sectioned, pulp tissue removed and the cavity enlarged. Teeth were painted with nail varnish to leave a 6-mm diameter circle on the buccal surface. Baseline color was measured spectrophotometrically. Teeth were randomized into a control group (n = 10) treated with 30 µl of glycerin base and a bleaching group (n = 10) exposed to 30 µl of 40% hydrogen peroxide for 1 hour. A linear low density polyethylene wrap was placed to prevent evaporation of the material. Acetate buffer was placed into the cavity and replenished every 10 minutes and placed into plastic tubes. Hydrogen peroxide amount was estimated spectrophotometrically using leukocrystal violet and horseradish peroxidase. Specimen color was remeasured immediately after bleaching, 1 hour, 1 day 1, 2 and 6 weeks postbleaching. Color change was measured per Commission Internationale de l'Eclairage methodology. Mann-Whitney procedure was used to assess baseline color measurements and total hydrogen peroxide penetration amount. Friedman's test was used to assess within group differences for color change and hydrogen peroxide penetration.RESULTS: There was significantly greater hydrogen peroxide penetration in the bleaching group (p < 0.05). Hydrogen peroxide penetration levels were constant throughout the 1-hour evaluation period in the bleaching group. The groups showed no difference at baseline with respect to any of L*a*b color measurements (p > 0.05). The postbleaching color measurement showed an increase of change in overall color (ΔE) and lightness (ΔL) up to 1 week followed by a gradual stabilization up to 6 weeks.CONCLUSION: This dynamic model provided information about the time course diffusion kinetics into the pulp cavity, demonstrating constant penetration of hydrogen peroxide into the pulp cavity during a 1-hour bleaching session.CLINICAL SIGNIFICANCE: A prolonged application of 40% hydrogen peroxide bleaching material for 1 hour produces constant penetration of hydrogen peroxide into the pulp cavity in vitro.
Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably ach... more Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism. One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant. Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I.C. Spray and Virahol had the largest mean zones of inhibition (11.33 vs 20.60 and 20.55 mm; p = 0.0001). The hypochlorite compounds Chlorox (1:10 dilution) and Dispatch had mean zones of inhibition similar to that of Cidex (11.08 and 11.25 mm vs 11.33 mm; p = not significant). The phenolic compounds OMNI II and Lysol had mean zones of inhibition smaller than that of Cidex (10.50 and 10.35 mm vs 11.33 mm; p &lt; 0.006), and the phosphoric acid and iodine-containing IodoFive had the smallest mean zone of inhibition (9.70 vs 11.33 mm; p = 0.0001). The alcohol-containing disinfectants had the largest zones of inhibition against resistant P. aeruginosa. These compounds may be more effective than glutaraldehyde for endoscopic equipment reprocessing.
ABSTRACT Objective: Chloride channels were suggested to act as fluoride exporters that protect ba... more ABSTRACT Objective: Chloride channels were suggested to act as fluoride exporters that protect bacteria from environmental fluoride toxicity. The involvement of chloride channels in fluoride resistance in mammalian cells remains unknown. The purpose of this study was to investigate the differential genetic expression of the CLCN family of voltage-gated chloride channel and the cystic fibrosis transmembrane conductance regulator (CFTR) between regular and induced fluoride-resistant L-929 cells in vitro. Methods: Fluoride-resistant L-929 cells to 90 ppm were induced in vitro by sequential exposure of regular L-929 cells (ATCC CCL-1, Manassas, VA) to concentration gradient ascending fluoride media. Total cellular RNA was isolated from both regular and 90ppm fluoride-resistant L-929 cells. cDNA was synthesized from extracted RNA and quantitative real-time PCR were used to determine the mRNA expression of CFTR and CLCN family (including CLCN1, CLCN2, CLCN3, CLCN4, CLCN5, CLCN6, CLCN7, CLCNKA and CLCNKB) in both types of L-929 cells. Results: In 90 ppm fluoride-resistant L-929 cells, the genetic expression of CLCN2 was up-regulated to about twice as that in the regular L-929 cells (p&lt;0.05), whereas the expression of CLCN1, CLCN3, CLCN4 and CFTR were down-regulated compared to the regular L-929 cells (p&lt;0.05). There were no significant difference in the genetic expression of CLCN5, CLCN6, CLCN7, CLCNKA and CLCNKB between the regular and 90 ppm fluoride-resistant L-929 cells. Conclusion: Under the condition of the present study, the results suggest that CLCN1, CLCN2, CLCN3, CLCN4 and CFTR play a potential role in the resistance of L-929 cells to high concentration of extracellular fluoride. Key words: Fluoride-resistant, Chloride channels, Gene expression, Fibroblasts
Substantivity of tetracycline HCl and chlorhexidine digluconate to human root dentin was assessed... more Substantivity of tetracycline HCl and chlorhexidine digluconate to human root dentin was assessed in vitro. 51 extracted single-rooted teeth, their crowns removed, were assigned to 1 of 4 treatments in groups of 12. A control groups included 3 roots. Each group was divided into 3 subgroups to allow evaluation of drug exposure for 1, 3 or 5 min. The roots were immersed in tetracycline HCl (10 or 50 mg/ml) or chlorhexidine digluconate (0.12 or 0.2%) solutions following root planning. Control roots were immersed in sterile saline (0.9%). Following drug immersion, the roots were transferred to tubes containing 2 ml tris buffered saline. The tubes were incubated at room temperature for 22 days. Desorption media were replaced at 24-h intervals. Removed media were examined for antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Roots immersed in tetracycline HCl 50 mg/ml released antimicrobial activity to successive desorption media for 14 days. Tetracycline HCl 10 mg/ml activity lasted 4 days. Roots subjected to chlorhexidine digluconate released antimicrobial activity for 24 h only. Within each treatment, there were no differences between the 3 exposure intervals of 1, 3 or 5 min. Our findings suggest usage of the periodontally exposed instrumented root as a depot for sustained release of tetracycline HCl, but not chlorhexidine digluconate, to the subgingival environment. The substantiveness of tetracycline HCl seems related to drug concentration rather than the exposure interval. Clinical trials are needed to confirm the clinical significance of these in vitro observations.
For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a ... more For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a 6-log reduction of mycobacterial inoculum under worst case conditions. The purpose of this study was to assess the adequacy of current guidelines for high level disinfection of GI endoscopes using alkaline glutaraldehyde in simulated-use testing. Various gastrointestinal endoscopes were contaminated with Mycobacterium chelonae in 46 experiments. Quantitative cultures were obtained from each endoscope channel separately after each step: inoculation, standardized manual cleaning, immersion in 2% glutaraldehyde (Cidex) for 10, 20, or 45 min at room temperature, 70% isopropanol rinse, and drying. Manual cleaning alone achieved a 4-log reduction. After 10 min of glutaraldehyde exposure, but before alcohol rinse, two of 10 experiments failed to achieve a 6-log reduction. However, after alcohol rinse, all 10 experiments achieved HLD. After 20 min of glutaraldehyde exposure, but before alcohol r...
Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably ach... more Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism. One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant. Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I....
To develop a model for experimental Streptococcus pneumoniae keratitis and to evaluate the chemot... more To develop a model for experimental Streptococcus pneumoniae keratitis and to evaluate the chemotherapeutic efficacy of 12 common topical antibiotics in vivo. Five-hundred (CFUs of log-phase S. pneumoniae were injected into the central corneal stroma of 36 eyes of 18 rabbits. After 0, 4, 8, 16, 24, and 48 hours, the in vivo growth was assayed as the CFU per cornea. Epithelial removal (to promote antibiotic entry and mimic human keratitis) was evaluated. Disc or tube dilution verification of the sensitivity or resistance of three S. pneumoniae strains was performed: a penicillin sensitive ("S"), an intermediate sensitive ("I"), and a resistant ("R") strain. Keratitis was established with S. pneumoniae "S" in 65 eyes, S. pneumoniae "I" in 107 eyes, and S. pneumoniae "R" in 78 eyes. Sixteen hours later, control corneas were harvested and the epithelium removed from treatment corneas. Every half hour saline, penicillin, gentami...
To test the possibility of pathogenic virus transmission into the operating suite during excimer ... more To test the possibility of pathogenic virus transmission into the operating suite during excimer laser treatment of corneal tissue. Such treatment vaporizes corneal tissue, which may put the surgeon at risk of infection from human immunodeficiency virus, hepatitis virus, or other viruses. We developed a model system to test the possibility of such virus transmission. Pseudorabies virus is a porcine enveloped herpesvirus similar in structure and life cycle to human immunodeficiency virus and herpes simplex virus. An excimer laser was used to ablate a virus-infected tissue culture plate while an uninfected tissue culture plate was in an inverted position over the infected plate. Six hundred laser pulses were applied. Pseudorabies virus in the excimer laser plume would, potentially, contact and infect the uninfected cells. The experiment was repeated 20 times with appropriate positive and negative controls. None of the 20 uninfected plates was infected by the laser plume rising from ab...
The use of saliva as a diagnostic fluid for the evaluation of periodontal health has gained atten... more The use of saliva as a diagnostic fluid for the evaluation of periodontal health has gained attention recently. Most published real-time PCR assays focused on quantification of bacteria in subgingival plaque, not in saliva. The aims of this study were to develop a real-time PCR assay for quantification of six periodontal pathogens in saliva and to establish a relationship between the amount of DNA (fg) and colony-forming unit (CFU). TaqMan primers/probe sets were used for the detection of Aggregatibacter actinomycetemcomitans (Aa), Eikenella corrodens (Ec), Fusobacterium nucleatum (Fn), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythia (Tf), and total bacteria. Six periodontal pathogens and total bacteria in saliva from 24 periodontally healthy individuals were determined. The relationship between the amount of DNA (fg) and CFU was established by measuring the concentrations of extracted bacterial DNA and CFU per milliliter of bacteria on agar plates. F...
Compendium of continuing education in dentistry (Jamesburg, N.J. : 1995), 2008
This article presents the results of a controlled clinical trial evaluating a new at-home treatme... more This article presents the results of a controlled clinical trial evaluating a new at-home treatment to improve gingival health. Designed for overnight application at the gingival margins and in the interproximal spaces, the product is a mucoadhesive gel containing 0.10% cetylpyridinium chloride (CPC) and 0.592% zinc gluconate (ZG). The authors assessed the efficacy and safety of the CPC/ZG gel in adults with low-to-moderate gingival and plaque index scores by comparing clinical and laboratory findings for subjects using the CPC/ZG gel with those for subjects using the control gel (0% CPC and 0.592% ZG). Clinical findings at 3 and 6 months showed statistically significant improvements in two of the three major indices of gingival health in the CPC/ZG group compared with the control group. The performance of the treatment gel was supported by results of microbial analyses of plaque samples.
Although in three different mouse tumor systems with corn oil as dietary fat we previously found ... more Although in three different mouse tumor systems with corn oil as dietary fat we previously found that milk protein decreased tumor development compared with beef, the results were reversed in 1,2-dimethylhydrazine (DMH)-injected mice. The purpose of this study was to determine if the latter result was due to the protein source. BALB/c mice (n = 280) were divided into five diet groups and injected 10 times at weekly intervals with DMH (20 mg/kg wt) or saline. Four diets contained 11% protein (casein, milk, or beef) and 5% fat (corn oil or beef tallow), and the AIN-76A diet was used as a control diet. The source of fat was a significant modulator of tumor development. Corn oil markedly increased total tumor volume and the number of tumors per mouse compared with beef tallow. Its tumor-enhancing effects were evident when it was combined with milk but not with casein. In addition, significantly lower lymphoproliferation and T-cell cytotoxicity against colon tumor cell targets was associated with corn oil consumption, whereas nonfat milk as the protein source was related to normal oxidative burst capacity of phagocytes. These results demonstrate that the source of dietary fat, in addition to the protein source, has a profound effect on both tumor development and immune responsiveness in this animal tumor system.
Substantivity of tetracycline HCl and chlorhexidine digluconate was assessed in extracted teeth. ... more Substantivity of tetracycline HCl and chlorhexidine digluconate was assessed in extracted teeth. Fifty periodontally compromised teeth scheduled for extraction with probing depths ranging between 6 and 12 mm were root planed and then irrigated in situ with 1 of 4 solutions: tetracycline HCl at concentrations of 10 or 50 mg/ml, 0.12% chlorhexidine digluconate, or 0.9% sterile saline. Each tooth was exposed to 150 ml of the respective irrigation solution. Following extractions, the teeth were transferred to tris buffered saline and incubated at room temperature for 22 days. Incubation solutions were replaced at 24-hour intervals. Removed solutions were examined for desorbed antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Tetracycline HCl 50 mg/ml exhibited significantly greater antimicrobial activity than chlorhexidine digluconate for 12 days and greater than saline for 16 days. Tetracycline HCl 10 mg/ml exhibited significantly greater antimicrobial activity than chlorhexidine digluconate and saline for 4 days. Chlorhexidine digluconate did not exhibit any significant antimicrobial activity at any time point. Our findings demonstrate long-lasting substantivity of tetracycline HCl, but not chlorhexidine digluconate, by teeth exposed to a single episode of pocket irrigation of their periodontally-exposed roots. The amount of antimicrobial activity retained is proportional to the concentration of tetracycline HCl used for irrigation.
Diabetes mellitus is believed to increase the risk and severity of periodontitis. However, less e... more Diabetes mellitus is believed to increase the risk and severity of periodontitis. However, less evidence is available on the converse effects of periodontitis on diabetes. The objective of the study was to investigate to what degree experimental periodontitis induced by Porphyromonas gingivalis might influence the onset and severity of diabetes in different mouse models. Twenty-eight male Tallyho/JngJ mice (type 2 diabetes), 20 male streptozotocin-induced diabetes C57BL/6J mice (type 1 diabetes) and 20 male C57BL/6J mice at 4 wks of age were evenly divided into two groups: periodontal infection and sham infection. Periodontitis was induced by Porphyromonas gingivalis W50 (P. gingivalis) oral inoculation before the development of diabetes. Sham-infected mice received vehicle as control. P. gingivalis in the oral cavity were identified by quantitative polymerase chain reaction. Fasting glucose, body weight and food intake levels were monitored and glucose tolerance tests were performed to assess glucose homeostasis for the onset and progression of diabetes. The level of alveolar bone loss and tumor necrosis factor-alpha were determined in week 20 when mice were killed. Mice in the infection groups developed more alveolar bone loss than those in sham-infection groups (Tallyho p = 0.021; C57-STZ p = 0.014; C57 p = 0.035). Hyperglycemic mice exhibited significantly more bone loss compared to those normal glucose mice (Tallyho vs. C57 p = 0.029; C57-STZ vs. C57 p = 0.024). The level of tumor necrosis factor-alpha was consistent with that of periodontal bone loss and hyperglycemia. There was no significant effect of mouse species on the amount of bone loss at the same level of blood glucose. No statistically significant difference or trend in glucose metabolism was found between the infection and sham-infection group. Diabetes enhanced the risk for periodontal disease induced by P. gingivalis. However, no converse impact was found between this periodontal infection and onset and severity of diabetes in both type 1 and 2 diabetes mice.
Journal of the California Dental Association, May 1, 2012
This study investigated sterilization of used implant impression copings and healing abutments. C... more This study investigated sterilization of used implant impression copings and healing abutments. Components were analyzed after contamination with Enterococcus foecalis, followed by multiple rounds of sterilization by both steam autoclave and Chemiclave protocols. The authors&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; results demonstrated that used components showed sterility equal to new components without any visible distortion. These data suggest that component resterilization and reuse may be justified or at least considered in clinical practice. Also, implications for cost savings in the placement of implants are advanced.
The Journal of Contemporary Dental Practice, Jan 7, 2012
AIM: To measure the time course hydrogen peroxide penetration into the pulp cavity and evaluate s... more AIM: To measure the time course hydrogen peroxide penetration into the pulp cavity and evaluate short-term tooth color changes after bleaching.MATERIALS AND METHODS: Twenty extracted human canines were sectioned, pulp tissue removed and the cavity enlarged. Teeth were painted with nail varnish to leave a 6-mm diameter circle on the buccal surface. Baseline color was measured spectrophotometrically. Teeth were randomized into a control group (n = 10) treated with 30 µl of glycerin base and a bleaching group (n = 10) exposed to 30 µl of 40% hydrogen peroxide for 1 hour. A linear low density polyethylene wrap was placed to prevent evaporation of the material. Acetate buffer was placed into the cavity and replenished every 10 minutes and placed into plastic tubes. Hydrogen peroxide amount was estimated spectrophotometrically using leukocrystal violet and horseradish peroxidase. Specimen color was remeasured immediately after bleaching, 1 hour, 1 day 1, 2 and 6 weeks postbleaching. Color change was measured per Commission Internationale de l'Eclairage methodology. Mann-Whitney procedure was used to assess baseline color measurements and total hydrogen peroxide penetration amount. Friedman's test was used to assess within group differences for color change and hydrogen peroxide penetration.RESULTS: There was significantly greater hydrogen peroxide penetration in the bleaching group (p < 0.05). Hydrogen peroxide penetration levels were constant throughout the 1-hour evaluation period in the bleaching group. The groups showed no difference at baseline with respect to any of L*a*b color measurements (p > 0.05). The postbleaching color measurement showed an increase of change in overall color (ΔE) and lightness (ΔL) up to 1 week followed by a gradual stabilization up to 6 weeks.CONCLUSION: This dynamic model provided information about the time course diffusion kinetics into the pulp cavity, demonstrating constant penetration of hydrogen peroxide into the pulp cavity during a 1-hour bleaching session.CLINICAL SIGNIFICANCE: A prolonged application of 40% hydrogen peroxide bleaching material for 1 hour produces constant penetration of hydrogen peroxide into the pulp cavity in vitro.
Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably ach... more Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism. One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant. Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I.C. Spray and Virahol had the largest mean zones of inhibition (11.33 vs 20.60 and 20.55 mm; p = 0.0001). The hypochlorite compounds Chlorox (1:10 dilution) and Dispatch had mean zones of inhibition similar to that of Cidex (11.08 and 11.25 mm vs 11.33 mm; p = not significant). The phenolic compounds OMNI II and Lysol had mean zones of inhibition smaller than that of Cidex (10.50 and 10.35 mm vs 11.33 mm; p &lt; 0.006), and the phosphoric acid and iodine-containing IodoFive had the smallest mean zone of inhibition (9.70 vs 11.33 mm; p = 0.0001). The alcohol-containing disinfectants had the largest zones of inhibition against resistant P. aeruginosa. These compounds may be more effective than glutaraldehyde for endoscopic equipment reprocessing.
ABSTRACT Objective: Chloride channels were suggested to act as fluoride exporters that protect ba... more ABSTRACT Objective: Chloride channels were suggested to act as fluoride exporters that protect bacteria from environmental fluoride toxicity. The involvement of chloride channels in fluoride resistance in mammalian cells remains unknown. The purpose of this study was to investigate the differential genetic expression of the CLCN family of voltage-gated chloride channel and the cystic fibrosis transmembrane conductance regulator (CFTR) between regular and induced fluoride-resistant L-929 cells in vitro. Methods: Fluoride-resistant L-929 cells to 90 ppm were induced in vitro by sequential exposure of regular L-929 cells (ATCC CCL-1, Manassas, VA) to concentration gradient ascending fluoride media. Total cellular RNA was isolated from both regular and 90ppm fluoride-resistant L-929 cells. cDNA was synthesized from extracted RNA and quantitative real-time PCR were used to determine the mRNA expression of CFTR and CLCN family (including CLCN1, CLCN2, CLCN3, CLCN4, CLCN5, CLCN6, CLCN7, CLCNKA and CLCNKB) in both types of L-929 cells. Results: In 90 ppm fluoride-resistant L-929 cells, the genetic expression of CLCN2 was up-regulated to about twice as that in the regular L-929 cells (p&lt;0.05), whereas the expression of CLCN1, CLCN3, CLCN4 and CFTR were down-regulated compared to the regular L-929 cells (p&lt;0.05). There were no significant difference in the genetic expression of CLCN5, CLCN6, CLCN7, CLCNKA and CLCNKB between the regular and 90 ppm fluoride-resistant L-929 cells. Conclusion: Under the condition of the present study, the results suggest that CLCN1, CLCN2, CLCN3, CLCN4 and CFTR play a potential role in the resistance of L-929 cells to high concentration of extracellular fluoride. Key words: Fluoride-resistant, Chloride channels, Gene expression, Fibroblasts
Substantivity of tetracycline HCl and chlorhexidine digluconate to human root dentin was assessed... more Substantivity of tetracycline HCl and chlorhexidine digluconate to human root dentin was assessed in vitro. 51 extracted single-rooted teeth, their crowns removed, were assigned to 1 of 4 treatments in groups of 12. A control groups included 3 roots. Each group was divided into 3 subgroups to allow evaluation of drug exposure for 1, 3 or 5 min. The roots were immersed in tetracycline HCl (10 or 50 mg/ml) or chlorhexidine digluconate (0.12 or 0.2%) solutions following root planning. Control roots were immersed in sterile saline (0.9%). Following drug immersion, the roots were transferred to tubes containing 2 ml tris buffered saline. The tubes were incubated at room temperature for 22 days. Desorption media were replaced at 24-h intervals. Removed media were examined for antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Roots immersed in tetracycline HCl 50 mg/ml released antimicrobial activity to successive desorption media for 14 days. Tetracycline HCl 10 mg/ml activity lasted 4 days. Roots subjected to chlorhexidine digluconate released antimicrobial activity for 24 h only. Within each treatment, there were no differences between the 3 exposure intervals of 1, 3 or 5 min. Our findings suggest usage of the periodontally exposed instrumented root as a depot for sustained release of tetracycline HCl, but not chlorhexidine digluconate, to the subgingival environment. The substantiveness of tetracycline HCl seems related to drug concentration rather than the exposure interval. Clinical trials are needed to confirm the clinical significance of these in vitro observations.
For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a ... more For a germicide to obtain a high level disinfection (HLD) claim, FDA requires demonstration of a 6-log reduction of mycobacterial inoculum under worst case conditions. The purpose of this study was to assess the adequacy of current guidelines for high level disinfection of GI endoscopes using alkaline glutaraldehyde in simulated-use testing. Various gastrointestinal endoscopes were contaminated with Mycobacterium chelonae in 46 experiments. Quantitative cultures were obtained from each endoscope channel separately after each step: inoculation, standardized manual cleaning, immersion in 2% glutaraldehyde (Cidex) for 10, 20, or 45 min at room temperature, 70% isopropanol rinse, and drying. Manual cleaning alone achieved a 4-log reduction. After 10 min of glutaraldehyde exposure, but before alcohol rinse, two of 10 experiments failed to achieve a 6-log reduction. However, after alcohol rinse, all 10 experiments achieved HLD. After 20 min of glutaraldehyde exposure, but before alcohol r...
Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably ach... more Previous studies have shown that high-level disinfection of GI endoscopes may not be reliably achieved using glutaraldehyde at room temperature. In our laboratory, we have isolated a strain of Pseudomonas aeruginosa that is resistant to disinfection with glutaraldehyde. We compared the bactericidal activity of various disinfectants against this organism. One hundred microliters of an overnight culture of this organism was spread onto blood agar plates. Twenty microliters of a disinfectant was placed on a sterile 7-mm filter paper, placed on the blood agar plate, and incubated overnight at 37 degrees C to determine the zone of inhibition for each disinfectant tested. Disinfectants included Cidex, Dispatch, Virahol, OMNI II, Lysol, IodoFive, Lysol I.C. Spray, and Chlorox. The zone of inhibition (i.e., clearing) roughly correlates with the bactericidal strength of the disinfectant. Compared with the glutaraldehyde-containing solution Cidex, the alcohol-containing disinfectants Lysol I....
To develop a model for experimental Streptococcus pneumoniae keratitis and to evaluate the chemot... more To develop a model for experimental Streptococcus pneumoniae keratitis and to evaluate the chemotherapeutic efficacy of 12 common topical antibiotics in vivo. Five-hundred (CFUs of log-phase S. pneumoniae were injected into the central corneal stroma of 36 eyes of 18 rabbits. After 0, 4, 8, 16, 24, and 48 hours, the in vivo growth was assayed as the CFU per cornea. Epithelial removal (to promote antibiotic entry and mimic human keratitis) was evaluated. Disc or tube dilution verification of the sensitivity or resistance of three S. pneumoniae strains was performed: a penicillin sensitive ("S"), an intermediate sensitive ("I"), and a resistant ("R") strain. Keratitis was established with S. pneumoniae "S" in 65 eyes, S. pneumoniae "I" in 107 eyes, and S. pneumoniae "R" in 78 eyes. Sixteen hours later, control corneas were harvested and the epithelium removed from treatment corneas. Every half hour saline, penicillin, gentami...
To test the possibility of pathogenic virus transmission into the operating suite during excimer ... more To test the possibility of pathogenic virus transmission into the operating suite during excimer laser treatment of corneal tissue. Such treatment vaporizes corneal tissue, which may put the surgeon at risk of infection from human immunodeficiency virus, hepatitis virus, or other viruses. We developed a model system to test the possibility of such virus transmission. Pseudorabies virus is a porcine enveloped herpesvirus similar in structure and life cycle to human immunodeficiency virus and herpes simplex virus. An excimer laser was used to ablate a virus-infected tissue culture plate while an uninfected tissue culture plate was in an inverted position over the infected plate. Six hundred laser pulses were applied. Pseudorabies virus in the excimer laser plume would, potentially, contact and infect the uninfected cells. The experiment was repeated 20 times with appropriate positive and negative controls. None of the 20 uninfected plates was infected by the laser plume rising from ab...
The use of saliva as a diagnostic fluid for the evaluation of periodontal health has gained atten... more The use of saliva as a diagnostic fluid for the evaluation of periodontal health has gained attention recently. Most published real-time PCR assays focused on quantification of bacteria in subgingival plaque, not in saliva. The aims of this study were to develop a real-time PCR assay for quantification of six periodontal pathogens in saliva and to establish a relationship between the amount of DNA (fg) and colony-forming unit (CFU). TaqMan primers/probe sets were used for the detection of Aggregatibacter actinomycetemcomitans (Aa), Eikenella corrodens (Ec), Fusobacterium nucleatum (Fn), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythia (Tf), and total bacteria. Six periodontal pathogens and total bacteria in saliva from 24 periodontally healthy individuals were determined. The relationship between the amount of DNA (fg) and CFU was established by measuring the concentrations of extracted bacterial DNA and CFU per milliliter of bacteria on agar plates. F...
Compendium of continuing education in dentistry (Jamesburg, N.J. : 1995), 2008
This article presents the results of a controlled clinical trial evaluating a new at-home treatme... more This article presents the results of a controlled clinical trial evaluating a new at-home treatment to improve gingival health. Designed for overnight application at the gingival margins and in the interproximal spaces, the product is a mucoadhesive gel containing 0.10% cetylpyridinium chloride (CPC) and 0.592% zinc gluconate (ZG). The authors assessed the efficacy and safety of the CPC/ZG gel in adults with low-to-moderate gingival and plaque index scores by comparing clinical and laboratory findings for subjects using the CPC/ZG gel with those for subjects using the control gel (0% CPC and 0.592% ZG). Clinical findings at 3 and 6 months showed statistically significant improvements in two of the three major indices of gingival health in the CPC/ZG group compared with the control group. The performance of the treatment gel was supported by results of microbial analyses of plaque samples.
Although in three different mouse tumor systems with corn oil as dietary fat we previously found ... more Although in three different mouse tumor systems with corn oil as dietary fat we previously found that milk protein decreased tumor development compared with beef, the results were reversed in 1,2-dimethylhydrazine (DMH)-injected mice. The purpose of this study was to determine if the latter result was due to the protein source. BALB/c mice (n = 280) were divided into five diet groups and injected 10 times at weekly intervals with DMH (20 mg/kg wt) or saline. Four diets contained 11% protein (casein, milk, or beef) and 5% fat (corn oil or beef tallow), and the AIN-76A diet was used as a control diet. The source of fat was a significant modulator of tumor development. Corn oil markedly increased total tumor volume and the number of tumors per mouse compared with beef tallow. Its tumor-enhancing effects were evident when it was combined with milk but not with casein. In addition, significantly lower lymphoproliferation and T-cell cytotoxicity against colon tumor cell targets was associated with corn oil consumption, whereas nonfat milk as the protein source was related to normal oxidative burst capacity of phagocytes. These results demonstrate that the source of dietary fat, in addition to the protein source, has a profound effect on both tumor development and immune responsiveness in this animal tumor system.
Substantivity of tetracycline HCl and chlorhexidine digluconate was assessed in extracted teeth. ... more Substantivity of tetracycline HCl and chlorhexidine digluconate was assessed in extracted teeth. Fifty periodontally compromised teeth scheduled for extraction with probing depths ranging between 6 and 12 mm were root planed and then irrigated in situ with 1 of 4 solutions: tetracycline HCl at concentrations of 10 or 50 mg/ml, 0.12% chlorhexidine digluconate, or 0.9% sterile saline. Each tooth was exposed to 150 ml of the respective irrigation solution. Following extractions, the teeth were transferred to tris buffered saline and incubated at room temperature for 22 days. Incubation solutions were replaced at 24-hour intervals. Removed solutions were examined for desorbed antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Tetracycline HCl 50 mg/ml exhibited significantly greater antimicrobial activity than chlorhexidine digluconate for 12 days and greater than saline for 16 days. Tetracycline HCl 10 mg/ml exhibited significantly greater antimicrobial activity than chlorhexidine digluconate and saline for 4 days. Chlorhexidine digluconate did not exhibit any significant antimicrobial activity at any time point. Our findings demonstrate long-lasting substantivity of tetracycline HCl, but not chlorhexidine digluconate, by teeth exposed to a single episode of pocket irrigation of their periodontally-exposed roots. The amount of antimicrobial activity retained is proportional to the concentration of tetracycline HCl used for irrigation.
Diabetes mellitus is believed to increase the risk and severity of periodontitis. However, less e... more Diabetes mellitus is believed to increase the risk and severity of periodontitis. However, less evidence is available on the converse effects of periodontitis on diabetes. The objective of the study was to investigate to what degree experimental periodontitis induced by Porphyromonas gingivalis might influence the onset and severity of diabetes in different mouse models. Twenty-eight male Tallyho/JngJ mice (type 2 diabetes), 20 male streptozotocin-induced diabetes C57BL/6J mice (type 1 diabetes) and 20 male C57BL/6J mice at 4 wks of age were evenly divided into two groups: periodontal infection and sham infection. Periodontitis was induced by Porphyromonas gingivalis W50 (P. gingivalis) oral inoculation before the development of diabetes. Sham-infected mice received vehicle as control. P. gingivalis in the oral cavity were identified by quantitative polymerase chain reaction. Fasting glucose, body weight and food intake levels were monitored and glucose tolerance tests were performed to assess glucose homeostasis for the onset and progression of diabetes. The level of alveolar bone loss and tumor necrosis factor-alpha were determined in week 20 when mice were killed. Mice in the infection groups developed more alveolar bone loss than those in sham-infection groups (Tallyho p = 0.021; C57-STZ p = 0.014; C57 p = 0.035). Hyperglycemic mice exhibited significantly more bone loss compared to those normal glucose mice (Tallyho vs. C57 p = 0.029; C57-STZ vs. C57 p = 0.024). The level of tumor necrosis factor-alpha was consistent with that of periodontal bone loss and hyperglycemia. There was no significant effect of mouse species on the amount of bone loss at the same level of blood glucose. No statistically significant difference or trend in glucose metabolism was found between the infection and sham-infection group. Diabetes enhanced the risk for periodontal disease induced by P. gingivalis. However, no converse impact was found between this periodontal infection and onset and severity of diabetes in both type 1 and 2 diabetes mice.
Uploads