Disinfection of bacterially contaminated hydrophilic PVS impression materials.

PURPOSE: This study evaluated disinfection of bacterially contaminated hydrophilic polyvinylsiloxane (PVS) and polyether impressions. MATERIALS AND METHODS: Four light-bodied PVS (Examix, Genie, Take 1, Aquasil) and one polyether (Impregum) impression materials were evaluated using three disinfectants (EcoTru [EnviroSystems], ProSpray [Certol], and bleach [diluted 1:9]) as spray and immersion disinfections for 10-minute exposures. Pseudomonas aeruginosa ATCC 15442, Salmonella choleraesius ATCC 10708, and Staphylococcus aureus ATCC 6538 was the microbial challenge. Test specimens were prepared using aluminum molds with ten tapered cones. Mucin covered each cone, followed by 0.01 mL of each bacterium. Impressions were made using low viscosity impression material that was injected over the cones and filled custom trays. One-half of the impressions were spray disinfected, while the others underwent immersion disinfection. Trays that were contaminated but not disinfected served as positive controls, while those not bacterially contaminated or disinfected served as negative controls. The impressions were poured with Silky Rock Die Stone, and after setting, two cones were placed within a sterile capsule and triturated into powder. Four milliliters of TRIS buffer (0.05 M, pH 7.0) containing sodium thiosulfate (0.0055% w/v) were poured in each tube. After mixing, the solution was serially diluted and spread-plated onto selective agars. After incubation, colony counting occurred. RESULTS: No viable bacteria transferred to casts from either spray- or immersion-disinfected impressions. Negative controls produced no microbial colonies. Positive controls produced on average 3.35 × 10(5) bacterial cells. CONCLUSION: Results suggest the methods used could disinfect contaminated impression materials. Microbial transfer from nondisinfected impressions to cones approached 33.5%.

The in vivo contamination of air-driven low-speed handpieces with prophylaxis angles.

BACKGROUND: The authors conducted an in vivo study to determine if low-speed handpiece motors can become contaminated with oral flora when used with prophylaxis angles. METHODS: This crossover study involved 20 subjects, two types of handpieces and three prophylaxis angles. The authors used each handpiece/prophylaxis angle system to polish teeth. They then collected samples, spiral-plated the specimens and incubated them at 37 degrees C anaerobically and aerobically (with 5 percent carbon dioxide). After incubation, the authors examined the plates for the presence of bacterial colonies. RESULTS: At least 75 percent of the handpiece/prophylaxis angle systems used on the 20 subjects had bacterial contamination for at least one cultured area. Of the 420 specimens, 258 (61.4 percent) produced bacterial growth. Contamination varied from zero to 6,300 colony-forming units per milliliter. CONCLUSIONS: These data suggest that the internal surfaces of low-speed handpieces can become microbially contaminated during use with prophylaxis angles. CLINICAL IMPLICATIONS: Unless low-speed handpieces are sterilized properly after each use, they pose a risk for crossinfection.

Internal contamination of air-driven low-speed handpieces and attached prophy angles.

BACKGROUND: In an in vitro crossover study, the authors investigated whether the interior of low-speed handpiece/prophy-angle systems becomes contaminated during operation and submersion into Geobacillus stearothermophilus. METHODS: This study involved two types of handpieces attached to eight brands of prophy angles. The researchers operated angles attached to sterile handpieces for 60 seconds. They then analyzed the inside surfaces of the angle, nosecone and motor. They tested each prophy angle and handpiece 10 times. RESULTS: In the 160 tests of handpieces contaminated at the prophy cup end, the spores traveled into the motor gears 32 times (20 percent). In the other 160 tests in which the motor gears were contaminated, the test bacterium traveled through the prophy cup in 75 instances (47 percent). CONCLUSIONS: The in vitro data suggest that low-speed handpiece motors can become contaminated internally during use with prophy angles. Also, internal contaminants appear to have been released from the handpiece. CLINICAL IMPLICATIONS: The results suggest that low-speed hand-pieces can become contaminated internally during use. Unless low-speed handpieces are sterilized properly between patients, they may become cross-contaminated.

Effects of delayed microbial analysis of dental unit water line specimens.

PURPOSE: Monitoring microbial concentrations in water emitted from dental unit water lines (DUWL) is an important safety procedure. Improper handling of test water specimens could give incorrect results. Thus, the objective of this study was to measure the effects delayed culturing might have on DUWL specimens. METHODS: First, 100 mL water specimens were obtained from 10 different handpiece service lines within the School. All units had independent water systems, used DI (deionized water) water and were routinely cleaned using an alkaline peroxide based product. Two specimens of 10 mL were removed from the bottles and placed into individual sterile conical tubes. One set of tubes was processed immediately. 0.05 mL of sterile 1.0% (w/v) sodium thiosulfate solution was added to undiluted and diluted (1:10 and 1:100 with sterile DI water) specimens. After mixing, specimens were spiral plated onto duplicate R2A plates and incubated at 21degrees C for 7 days. Colonies were then counted and the cfu/mL of each original specimen determined. Another set of tubes was placed into a shipping envelope and mailed out to the School. Upon receipt, the tubes were processed as described above. The remaining 80 mL of water in the collection bottles were divided equally into new sterile tubes. One tube was left at 21 degrees C, while the other was placed into a 37 degrees C incubator. Aliquots were processed immediately and then after 1, 3 and 7 days. Next, 30 mL water specimens were obtained from 15 handpiece service lines in three outside clinics. All units had independent water systems, used DI water and were routinely cleaned with an alkaline peroxide-based product. Specimens were then divided equally into three sterile conical tubes. One of the tubes was transported (at 4 degrees C) to the laboratory and immediately processed as described. At the collection site, the second tube was placed into a padded envelope and mailed back to the School. The third tube was returned by overnight delivery using a Cool Pack type container. Upon receipt, all the tubes were processed as described previously. RESULTS: The 10 handpiece waterline specimens processed immediately ranged from 0 to 1000 cfu/mL. Holding specimens at 21 degrees C produced radically higher bacterial counts (1540-866,000 cfu/mL) in water from 90% of the handpieces. Holding at 37 degrees C produced unacceptably high bacterial counts in only 50% of the handpiece specimens. Mailed specimens were cultured 5 days after collection and water of unacceptable quality water was noted in 70% of the specimens. In another experimental set, mailed specimens arrived after 72 hours and were an average of 20 degrees C. Express sent specimens came the next morning at an average temperature of 4.5 degrees C. Only one waterline specimen processed immediately contained more than 500 cfu/mL. In contrast, 80% of specimens returned by post at ambient temperature had unacceptably high bacterial counts (780-376,000 cfu/mL). Express sent specimens produced the same results as those processed immediately.

Environmental surface asepsis.

Environmental surface disinfection is easily accomplished with precleaning and disinfection techniques, and prepared surfaces or difficult-to-clean items can be covered with impermeable barriers. When carried out effectively, both practitioners and patients are protected from exposure to microorganisms that transmit disease and cause illness.

The effect of distillation and line cleaning on the quality of water emitted from dental units.

PURPOSE: To monitor water emitted from dental units connected to centralized water distillation units fitted with reservoirs for dispensing chemicals designed to control biofilms. METHODS: Three private practice dental offices participated in the study. None of the office operatories had independent water reservoir (bottle) systems or any other type of water treatment equipment. Initially, 5.0 mL water specimens were obtained from the handpiece and three-way syringe service lines as well as from the sink faucets in three operatories in each office. Specimens were collected at the end of the workweek. Specimens were neutralized for residual chlorine, diluted and spiral plated onto R2A agar. Aerobic incubation was allowed for 7 days at 21 degrees C. Numbers of colonies were then determined and expressed as CFU/mL. If water specimens containing more than 200 CFU/mL were detected, the offices were equipped with water distillers with attached cleaning solution dispensers. The units allowed distilled water to move under normal pressure to all connected dental units. When cleaning, the distillers were inactivated, which allowed cleaning fluid to move under pressure from the dispensers through all unit waterlines. The waterline-cleaning scheme followed the manufacturer recommendations. The presence of no more than 200 CFU/mL in emitted water was then established and a regimen of weekly cleanings applied for 3 weeks. Water specimens were always collected on the last workday of the week. Then, cleaning was suspended and weekly monitoring performed. Cleaning was restored immediately after detection of more than 200 CFU/mL. RESULTS: Levels of microbial contamination prior to the initiation of cleaning indicated marked variability (720-332,000 CFU/mL) and that water containing less than 200 CFU/mL was not being emitted from any operatory water source. However, sought-after water was consistently obtained over a period of 3 weeks from all unit sources after line-cleaning processes were completed. Water containing less than 200 CFU/mL was obtained from all unit sources in the three offices after skipping of one weekly cleaning. In one office, cleaning was suspended for 3 weeks without affecting water quality. Resumption of weekly cleanings produced desirable water from all sources in the three offices within 2 weeks. Results indicate that dental units attached to centralized combined water distillation-cleaning solution distribution systems can produce water with less than 200 CFU/mL and that the missing of one weekly cleaning did not negatively affect water quality.

An immunization program for dental practices.

Immunization helps prevent acquisition of diseases, many of which were once common in the United States. Immunity is generally achieved by administering live or dead pathogens or their components. Vaccines used for active immunization consist of live (attenuated) organisms, killed whole or split organisms, microbial components, or inactivated toxins (toxoids). Some cases require the administration of antibody-containing gamma globulin injections. According to the new Centers for Disease Control and Prevention Guideline on infection control, dental practices must develop a written, comprehensive policy on immunizing workers and refer personnel to qualified professionals for evaluation and, when necessary, for all appropriate immunizations.

Environmental surface infection control, 2003.

Infection control guidelines address the routine use of disposable covers and cleaning and disinfecting treatment-area surfaces contaminated during patient care. While the rationale and approaches for accomplishing environmental surface disinfection have been considered in many previous infection control recommendations, exaggerated claims have led to some confusion regarding the wide variety of available surface covers and disinfectant products. The Centers for Disease Control and Prevention Guideline for Infection Control in Dental Health-Care Settings, 2003, considers the current state of scientific and clinical knowledge in environmental infection control, reinforce basic principles, and provide updated recommendations aimed at minimizing the potential for microbial cross-contamination and cross-infection from inanimate surfaces.

Infection control practices for dental radiography.

Infection control for dental radiography employs the same materials, processes, and techniques used in the operatory, yet unless proper procedures are established and followed, there is a definite potential for cross-contamination to clinical area surfaces and DHCP. In general, the aseptic practices used are relatively simple and inexpensive, yet they require complete application in every situation.

Phase I study of intravenously administered ATI-1123, a liposomal docetaxel formulation in patients with advanced solid tumors.

PURPOSE: ATI-1123 is a liposomal formulation of docetaxel and may be administered without the premedications and hypersensitivity reactions. This Phase I study examines the safety, tolerability, pharmacokinetics (PKs), and antitumor activity of ATI-1123. METHODS: Patients with advanced solid malignancies received escalating doses of ATI-1123 intravenously over 1-h every 3 weeks. The dosing commenced using an accelerated titration design and was followed by a modified 3 + 3 Fibonacci schema to determine maximally tolerated dose (MTD). Plasma was analyzed for encapsulated/non-encapsulated docetaxel; PK analyses were performed using model independent method. Response was assessed using RECIST criteria. RESULTS: In total, 29 patients received doses ranging from 15 to 110 mg/m(2). At 110 mg/m(2), two of six patients experienced dose-limiting toxicities including grade 3 stomatitis and febrile neutropenia. The 90 mg/m(2) cohort was expanded to ten patients and identified as the MTD. The most common adverse events were fatigue, nausea, neutropenia, anemia, anorexia, and diarrhea. ATI-1123 exhibited linear and dose proportional PKs. One patient with lung cancer had confirmed partial response, and stable disease was observed in 75 % patients. CONCLUSIONS: ATI-1123 demonstrated an acceptable tolerability and favorable PK profile in patients with solid tumors. Our results provide support for Phase II trials to determine the antitumor activity of this drug.

The effect of long-term disinfection on clinical contact surfaces.

BACKGROUND: The author measured the effect long-term disinfection had on common types of dental office environmental surfaces. METHODS: The author tested nine common dental surfaces and six spray disinfectants, as well as a tap water control. The author used the "spray-wipe-spray" method with paper towels to disinfect the surfaces. Each surface was disinfected 1,920 times, which was an estimate of the number of cleanings per year. After every 100 disinfections, the author conducted blood removal testing of the surface, which monitored residual blood and disinfectant cleaning ability. RESULTS: The surface that was most difficult to clean was textured vinyl, followed by smooth vinyl, enameled metal, service line rubber hosing and brushed aluminum. Diluted bleach affected surfaces the most, which resulted in higher blood removal scores. CONCLUSIONS: When compared with the control, Birex SE had equal or better cleaning scores across time, which might indicate that its use caused little change in the integrity of the surfaces. The results for the other disinfectants varied. CLINICAL IMPLICATIONS: Disinfectants should have good antimicrobial activity and minimal negative impact on the integrity of the surfaces being disinfected. Effective disinfection is highly dependent on efficient cleaning (removal of the bioburden present).

Microbial contamination and the sterilization/disinfection of surgical guides used in the placement of endosteal implants.

PURPOSE: The purpose of this study was twofold: (1) to estimate the level of microbial contamination found on commercial guides (CG) and in-house laboratory guides (LG) prior to use, and (2) to evaluate the antimicrobial potential of disinfectants commonly used in dentistry to decontaminate heat-sensitive surgical guides. Ethylene oxide gas was used as the positive control; sterile water served as a negative control. MATERIALS AND METHODS: Evaluation of CGs and LGs for bacterial contamination occurred soon after their arrival in the laboratory. Some guides went directly into tubes of trypticase soy broth solution, vortexed and equally divided into two tubes. One tube went into an 80°C bath for 19 minutes, while the other stayed at room temperature. After plating, half of the samples underwent anaerobic incubation. All incubation was for 48 hours at 37°C. Other guides underwent water rinsing or disinfection by various methods for 5 or 15 minutes or ethylene oxide gas sterilization prior to sampling. RESULTS: Untreated CG specimens showed modest levels of bacterial contamination, with most colonies coming from liquid specimens not exposed to 80°C. LG specimens had more bacteria from both heat-treated and non-heat-treated aliquots. Chlorhexidine gluconate, diluted bleach, and water rinsing were not able to completely eliminate microorganisms on the specimens, but no viable microorganisms were present on specimens treated with gas sterilization or 70% ethanol for 15 minutes. CONCLUSION: CGs and LGs, on average, had different levels of bacterial contamination prior to disinfection. Water, chlorhexidine gluconate, and diluted bleach were not totally successful in decontaminating the surgical guides, but no growth was found after 15 minutes of immersion in 70% ethanol. Preferably, surgical guides should be submerged in 70% alcohol for a minimum of 15 minutes or undergo sterilization using ethylene oxide gas.

Controlling bacterial contamination of dental impression guns.

BACKGROUND: Dental impression material handgun cartridge dispensers are contaminated easily during clinical use. The authors attempted to quantify contamination by bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), of impression guns used in an academic dental clinic after five infection-prevention protocols were followed. METHODS: The authors obtained samples from four commercially available impression guns at four specific sites (button, handle, latch, trigger) after routine clinical use, disinfection, steam sterilization (also known as autoclaving), steam sterilization followed by use of plastic impression gun covers and steam sterilization followed by use of plastic impression gun covers and disinfection. RESULTS: The authors found that after routine clinical use, bacteria-including MRSA-heavily contaminated the impression guns. After the impression guns underwent disinfection, there was a 6 percent decrease in bacterial counts. The use of steam sterilization achieved sterility without harming the impression guns. Use of steam-sterilized impression guns with plastic impression gun covers decreased bacterial isolates by approximately 60 percent. Use of steam-sterilized impression guns plus covers and disinfection resulted in an approximately 95 percent reduction in contamination. CONCLUSIONS: The use of common infection-prevention methods appears to reduce the bacterial counts, including those of MRSA. Bacterial contamination was lowest after steam sterilization, followed by the use of plastic impression gun covers and disinfection. CLINICAL IMPLICATIONS: Use of contaminated impression guns on successive patients could increase the risk of causing cross-transmission of disease. The use of sterilization, plus plastic impression gun covers and disinfection, for impression guns after each use could be an effective and practical infection-control method for dental practices.