Autoclaving of lubricated dental instruments.

Test organisms forced mechanically into lubricated, rotating dental instruments (handpieces) were all killed during autoclaving at 134 degrees C for 8 min, even when protected by serum and oil. The test organisms were: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and spores of Bacillus stearothermophilus. Also when testing the sterility of autoclaved simulated instrument surfaces (brass cylinders and pieces of a cotton fabric) which had been inoculated with bacteria and dried before they were sprayed with oil, there was no growth of the test organisms. In addition to the other test organisms, spores of Bacillus subtilis and Gram-positive, anaerobic bacteria isolated from used handpieces that had been exposed to several autoclavings were used. Some of the handpieces that had been left to dry after use in the dentist's office before they were autoclaved, were shown not to be sterile. Therefore, the authors suggest that autoclaving of the instruments should take place shortly after use and prescribed cleaning.     

Autoclave sterilization of dental handpieces: A literature review

PurposeThe present review aimed to investigate autoclave sterilization of dental handpieces based on available studies.Study selectionThe sterilizing efficiency of dental handpieces with autoclave is mainly affected by the types of apparatus (N, B, and S), the packaging with sterilizing pouch, cleaning, and lubrication. These subjects were reviewed based on the in vitro experimental studies.ResultsDental handpieces can be sterilized, including inactivation of heat-resistant bacterial spores, with type B or type S sterilizers, regardless of the use of a sterilization pouch. In contrast, although type N autoclaves are capable of sterilization of general bacteria such as Streptococcus salivarius even in a sterilization pouch if instruments are washed beforehand, complete sterilization of the wrapped handpiece is not always achieved. Therefore, to achieve sterilization efficiency with type N autoclaves, processing without any packaging is recommended. As regards cleaning of handpiece, although contamination decreases with irrigation and wiping of handpieces, all reports concluded that these treatments alone do not achieve complete decontamination of reusable handpieces.ConclusionAlthough type B and type S autoclaves allow us to sterilize the dental handpieces, it is important to realize that complete sterilization of the handpiece is not always achieved by type N autoclave. Understanding autoclave processing of handpieces is essential for dental practice to deliver the safe dental care.     

5种灭菌器对牙科手机性能的影响

目的 了解5种灭菌器对牙科手机机械性能的影响情况。方法 用5种灭菌器分别对4把牙科手机进行灭菌200次，每完成10次灭菌全过程检测一遍牙科手机的夹持力和转速。结果 经200次灭菌后20支牙科手机中，1支停转，另有8支转速下降，低于30万转／分钟，但高于16万转／分钟．可满足基本使用要求。灭菌时间最短的灭菌器只明显影响一支牙科手机的转速，其他灭菌器均明显影响两支牙科手机的转速。结论 灭菌时间短对牙科手机机械性能影响小，灭菌前应做好牙科手机的清洁和润滑，以减少机械性能损耗。     

两种消毒方法对牙科手机灭菌效果的评价

目的 :比较含氯消毒剂浸泡法和环氧乙烷气体灭菌法对牙科手机的灭菌效果。方法 :利用枯草杆菌黑色变种芽孢和乙肝表面抗原阳性血清污染牙科手机 ,消毒后进行定量杀菌实验 ,用酶联免疫吸附实验 (ELISA)法检测HBsAg 结果 :牙科手机浸泡在有效氯含量为 30 0 0× 10 -6的消毒剂中 30分钟 ,细菌杀灭率及乙肝表面抗原的抗原灭活率均未达到 10 0 % ,而环氧乙烷灭菌法可达到 10 0 %。结论 :环氧乙烷灭菌牙科手机效果可靠。     

Proper monitoring of sterilization procedures used in oral surgery

The sterilization procedures used by oral surgeons in Norway have been surveyed. In 22 of the 25 oral surgical clinics controlled, instruments were sterilized by saturated steam at 121 degrees C or 134 degrees C; 3 used a dry heat oven sterilizer; dry heat and/or gas sterilization procedures supplemented steam sterilization in 17 clinics. When these sterilization procedures were monitored with biological indicators, 5 autoclaves (challenged with B. stearothermophilus spores), 2 dry heat sterilizers (B. subtilis spores), and all the Harvey Chemiclaves tested (B. subtilis spores) did not inactivate the bacterial spores. A biological monitoring system that fulfills the valid requirements for sterilization procedures given by the national health authorities and that is reliable, convenient, economical and self-contained should be used routinely in oral surgery clinics.     

Infection control and contaminated waste disposal practices in Southern Sydney Area Health Service Dental Clinics

The sterilization and contaminated waste disposal practices in all 14 dental clinics operated by the Southern Sydney Area Health Service were surveyed. All of the clinics used autoclaves for sterilization. All hand instruments, handpieces and triplex syringes were autoclaved between patients. Chemical disinfection solutions were used in 12 of the 14 dental clinics, mainly for surface decontamination. Five dental clinics had separate storage areas for contaminated waste which compiled with contaminated waste separation and disposal guidelines. The practice of recapping needles with fingers and some inadequate washing facilites are areas that require particular attention.     

Autoclaving of lubricated dental instruments

abstract — Test organisms forced mechanically into lubricated, rotating dental instruments (hand pieces) were all killed during autoclaving at 134®C for 8 min, even when protected by serum and oil. The test organisms were: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans , and spores of Bacillus stearothermophilus . Also when testing the sterility of autoclaved simulated instrument surfaces (brass cylinders and pieces of a cotton fabric) which had been inoculated with bacteria and dried before they were sprayed with oil, there was no growth of the test organisms. In addition to the other test organisms, spores of Bacillus subtilis and Gram-positive, anaerobic bacteria isolated from used hand pieces that had been exposed to several autoclaving were used. Some of the hand pieces that had been left to dry after use in the dentist's office before they were autoclaved, were shown not to be sterile. Therefore, the authors suggest that autoclaving of the instruments should take place shortly after use and prescribed cleaning.     

The performance of air-turbine handpieces in general dental practice

OBJECTIVE: To investigate variation in performance measures of fibre-optic, high-speed air-turbine handpieces during the course of daily use in general dental practice. MATERIALS AND METHODS: Four groups of five new high-speed fibre-optic handpieces were used in the routine treatment of patients over a period of 30 months by four general dental practitioners in two dental practices: Groups A, B: Super-Torque Lux 3 650B (KaVo, Biberach, Germany); Group C: BORA 898LE (BienAir SA, Bienne, Switzerland) and Group D: Toplight (W&H Dentalwerk, Burmoos, Austria). The dental practice teams had been rehearsed in the procedures to be followed before starting the study. Each dentist used the handpieces in strict rotation, while the groups were rotated monthly between practitioners. Four performance characteristics were measured before use, then at regular intervals: free-running speed (Hz) and bearing resistance (microNm) were measured using a purpose-built testing machine (Darvell-Dyson); illuminance (lux) and sound pressure level (dB(A)) were also measured. Handpieces were cleaned and lubricated in accordance with manufacturers' directions; all were autoclaved wet at 134 degrees C for three minutes. RESULTS: Free-running speed showed an initial increase after use for Groups A, B and C, which may be associated with a decrease in bearing resistance. All handpieces in Group C suffered bearing failure between months 21 and 23, preceded by a substantial increase in noise, while those in Group D suffered failure of the fibreoptic system between months 18 and 24. Other deterioration due to use was identified but Groups A, B and D were still in use at month 30. CONCLUSIONS: Variation in free-running speed, bearing resistance, illuminance and sound pressure level can be used effectively to monitor changes in air-turbine handpieces due to normal use. Although an increase in bearing resistance is associated with decreasing free-running speed, noise appears to be a useful indicator of imminent bearing failure. Assiduous adherence to manufacturers' directions for cleaning and lubrication may have contributed to increased bearing life.     

Pulpal temperature increases with Er:YAG laser and high-speed handpieces

STATEMENT OF PROBLEM: During tooth preparation, both high-speed handpieces and lasers generate heat, which, if not controlled, can cause pulpal necrosis. PURPOSE: The aim of this study was to compare temperature increases produced by a high-speed dental handpiece with those produced by a relatively new instrument, the Er:YAG (erbium: yttrium-aluminum-garnet) laser. MATERIALS AND METHODS: Thirty bovine mandibular incisors were reduced to an enamel/dentin thickness of 2.5 mm. Class V preparations were completed to a depth of 2.0 mm, measured with a caliper or by a mark on the burs. A thermocouple was placed inside the pulp chamber to determine temperature increases (degrees C). Analysis was performed on the following groups (n=10): Group I, high-speed handpiece without water cooling, Group II, high-speed handpiece with water cooling (30 mL/min), and Group III, the noncontact Er:YAG laser (2.94 microm at 350 mJ/10 Hz) with water cooling (4.5 mL/min). The temperature increases were recorded by a computer linked to the thermocouples. The data were analyzed using the Kruskal-Wallis test. The Dunn multiple comparison test was used as post hoc test (alpha=.05). RESULTS: The average temperature rises were: 11.64 degrees C (+/- 4.35) for Group I, 0.96 degrees C (+/- 0.71) for Group II, and 2.69 degrees C (+/- 1.12) for Group III. There were no statistical differences between Groups II and III; both II and III differed from Group I significantly (P=.000 and P=.002, respectively). CONCLUSION: The preparations made with the high-speed and the laser instrument generated similar heat increases under water cooling. Water cooling was essential to avoid destructive temperature increases when using both the high-speed handpiece and laser.     

Autoclave use in dental practice in the Republic of Ireland

AIMS: To assess by postal questionnaire, cross-infection control methods, especially sterilisation procedures, of 700 general dental practitioners in the Republic of Ireland, and to biologically monitor steam pressure sterilisers or autoclaves in their practices. MAIN OUTCOME MEASURES: Methods of instrument cleaning and sterilisation, autoclave efficacy. RESULTS: A response rate of 40% with all, except one practitioner, using steam sterilisation. 49% also reported the use of chemical sterilisation with a quarter of these using glutaraldehyde. However, instrument soaking time varied greatly from 2.5 minutes to 74 hours. Methods of instrument cleaning prior to autoclaving were as follows: scrubbing by hand 41.5%, ultrasonic cleaning 7.0%, combination of both 50%. 52.9% of the respondents did not autoclave their dental handpieces and only 44.7% disinfected impressions before sending them to the laboratory. The autoclaves of thirty practitioners (11.3%) did not pass the initial biological test. Following counselling about possible causes of failure, four autoclaves (1.5%) failed a repeat biological test. However, seven practitioners did not return the repeat biological test. CONCLUSIONS: Some aspects of recommended cross-infection control procedures are well adhered to, e.g. instrument cleaning, but further education is required in certain key areas, in particular the use of chemical sterilisation, dental handpiece autoclaving and impression disinfection. There is also a need to increase awareness of the importance of routine autoclave servicing and calibration, along with validation and monitoring.     

Biological monitoring of sterilizers and sterilization failures in Norwegian dental offices in 1985 and 1996.

It is essential that dental office sterilizers be regularly challenged with biological indicators (BIs) in order to prove that the test spores are being killed during sterilization. The aims of the study were to biologically monitor Norwegian dental office sterilizers and to identify factors contributing to sterilization failure. In 1985, participants received a packet containing: (i) 4 BI units; (ii) a set of instructions; (iii) a questionnaire concerning operation (including biological monitoring) of the office sterilizer(s), and (iv) a return-address envelope. In 1996, offices were sent (i) a survey which included demographic questions and inquiries concerning instrument sterilization processes; (ii) 2 sets of 3 BI units with instructions for their use on 2 different days; (iii) 1 control BI unit that was not to be processed, and (iv) a return-address envelope. Both private and public offices participated. Response rate to the 1996 study was 60%, which was 9.1% of all dental offices in Norway. Testing results indicated a 6.3% overall sterilization failure rate. Three out of 163 steam autoclaves (SAs) (1.8% of total) and 14 out of 109 dry heat (DH) ovens (12.8% of total) failed. DH ovens were over 7 times more likely to fail BI testing than were SAs (chi2, P < 0.01). Demographic or hygiene procedural factors could not be correlated to sterilization performance (chi2, P > 0.05). The failure rate for SAs (n = 216) in 1985 was almost 5 times greater than in 1996 (8.8% vs 1.8%). Improvement in sterilizer performance during the decade may be related to issuance in 1986 of Norway's 1st infection control guidelines for dentistry and greater awareness of infection control practices and/or to increases over the previous 10 years in the number of postgraduate courses offered in infection control. The current Norwegian guidelines on infection control practices in public health services, including dentistry, recommend regular biological monitoring of sterilizers without specifying how often. There is a lack of information among Norwegian dentists as to how frequently dental office sterilizers should be regularly monitored by BI.     

Outcome of sterilization by steam autoclaves in Danish dental offices

The aims of this study were to evaluate the performance of autoclaves and the use of biologic indicators for sterilization control, and to look for predictor variables for improperly functioning autoclaves in Danish dental offices. The study population comprised 314 Danish dental offices (participation rate 94%); 177 from the public Child Dental Service (CDS) and 137 from private practice. A minor questionnaire and five biologic indicators (Attest Biological Indicator for Steam Sterilization, 3M) were sent to the participants. CDS offices were found more inclined to use biologic indicators than PP offices (P less than 0.00001). Among CDS autoclaves 2.3% (95% confidence limit: 0.9-5.7%) failed to sterilize compared to 7.3% (95% confidence limit: 4.0-12.9) of the PP autoclaves. This difference is not statistically significant, but the confidence intervals indicate a possible true difference in favor of a better outcome in the CDS offices. Looking at the whole sample no other predictor variable for inadequate sterilization could be determined as differences were statistically insignificant with regard to years of professional experience, age and brand of autoclave, and use of biological control. Recommendations from an official body stating the approved types of sterilization control in dental offices would be of value.     

Effects of the Nd:YAG dental laser on plasma-sprayed and hydroxyapatite-coated titanium dental implants: surface alteration and attempted sterilization.

The Nd:YAG dental laser has been recommended for a number of applications, including the decontamination or sterilization of surfaces of dental implants that are diseased or failing. The effects of laser irradiation in vitro (1) on the surface properties of plasma-sprayed titanium and plasma-sprayed hydroxyapatite-coated titanium dental implants, and (2) on the potential to sterilize those surfaces after contamination with spores of Bacillus subtilis have been examined. Surface effects were examined by scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction after laser irradiation at 0.3, 2.0, and 3.0 W using either contact or noncontact handpieces. Controls received no laser irradiation. Melting, loss of porosity, and other surface alterations were observed on both types of implants, even with the lowest power setting. For the sterilization study, both types of implants were first sterilized by exposure to ethylene oxide and then contaminated with spores of B subtilis. After laser irradiation, the implants were transferred to sterile growth medium and incubated. Laser irradiation did not sterilize either type of implant. The spore-contaminated implants in the control group were successfully sterilized with ethylene oxide.     

Biological monitoring of sterilizers and sterilization failures in Norwegian dental offices in 1985 and 1996

It is essential that dental office sterilizers be regularly challenged with biological indicators (BIs) in order to prove that the test spores are being killed during sterilization. The aims of the study were to biologically monitor Norwegian dental office sterilizers and to identify factors contributing to sterilization failure. In 1985, participants received a packet containing: (i) 4 BI units; (ii) a set of instructions; (iii) a questionnaire concerning operation (including biological monitoring) of the office sterilizer(s), and (iv) a return-address envelope. In 1996, offices were sent (i) a survey which included demographic questions and inquiries concerning instrument sterilization processes; (ii) 2 sets of 3 BI units with instructions for their use on 2 different days; (iii) 1 control BI unit that was not to be processed, and (iv) a return-address envelope. Both private and public offices participated. Response rate to the 1996 study was 60%, which was 9.1% of all dental offices in Norway. Testing results indicated a 6.3% overall sterilization failure rate. Three out of 163 steam autoclaves (SAs) (1.8% of total) and 14 out of 109 dry heat (DH) ovens (12.8% of total) failed. DH ovens were over 7 times more likely to fail BI testing than were SAs (χ², P < 0.01). Demographic or hygiene procedural factors could not be correlated to sterilization performance (χ², P > 0.05). The failure rate for SAs (n = 216) in 1985 was almost 5 times greater than in 1996 (8.8% vs 1.8%). Improvement in sterilizer performance during the decade may be related to issuance in 1986 of Norway's 1st infection control guidelines for dentistry and greater awareness of infection control practices and/or to increases over the previous 10 years in the number of postgraduate courses offered in infection control. The current Norwegian guidelines on infection control practices in public health services, including dentistry, recommend regular biological monitoring of sterilizers without specifying how often. There is a lack of information among Norwegian dentists as to how frequently dental office sterilizers should be regularly monitored by BI.

     

Evaluation of a dental unit with a built-in decontamination system

The efficacy of a dental unit equipped with a system that disinfects and sterilizes the water tubing by flushing with glutaraldehyde was evaluated by inserting Bacillus megaterium spores and Pseudomonas and Moraxella species into the water tubing. Up to 10(8) Pseudomonas and Moraxella organisms were killed during the disinfection cycle, but Bacillus megaterium spores were not. Up to 10(5) spores were eradicated by the sterilization cycle, although the system did not consistently kill 10(8) spores. The water tubing of the new unit was not naturally colonized by water bacteria during an 8-month period prior to the study. Evidence suggested that this was due to antimicrobial activity associated with the plastic tubing; therefore, microbial contamination of new dental units, irrespective of their design, would not be expected, until the inhibitory factor in the plastic tubing has leached out.     

Efficiency of combined action of a chemical disinfectant and plasma sterilization on stomatological instruments and casts

The efficiency of combined treatment of dentures by argon plasma and chemical disinfectant Ocadez is compared using anaerobic culturing of oral bacteria and polymerase chain reaction with hepatitis B, C, and D virus primers. Different protocols of processing dental instruments and casts directly after dentist's manipulations with outpatients were tried and model experiments with hepatitis viruses were carried out. The optimal protocol of plasma sterilization is as follows: 10 min at 86-90 degrees C after treatment with Ocadez or 15 min without additional chemical treatment.     

Dynamic ultraviolet sterilization of different implant types

This paper investigates the use of the dynamic ultraviolet sterilization process with various dental implants, stainless steel orthopedic cortical bone screws, and polysulfone polymer healing caps. These biomaterials were inoculated with the spores of Bacillus subtilis and Bacillus stearothermophilus. They were then exposed to dynamic ultraviolet radiation in the chamber of a BUD Ultraviolet Device. Samples were incubated in trypticase soy broth at 37 degrees C and 56 degrees C, and they were subcultured onto an enriched agar medium. Results indicate that 16 seconds of dynamic ultraviolet radiation is effective in sterilizing these materials. This is significantly less time than other sterilization techniques presently used.     

Monitoring dental sterilizers' effectiveness using biological indicators

The purpose of this study was to evaluate the effectiveness of dental office sterilizers as measured by their ability to kill bacterial spores present on biological indicator strips. The biological indicators used in this study contained two different spores, Bacillus stearothermophilus and Bacillus subtilis (Spordi, AMSCO/Medical Products). Ten spore test strips were sent to 87 dental offices; 51 sterilizers were tested. Office personnel were instructed to place four strips in the center of a normal sterilization load and process the load. The procedure was repeated on a second day. The processed strips, along with two unprocessed control strips, were returned by mail for laboratory culturing. The results indicated the overall failure rate (positive test) of sterlizers tested for both days was 51% at the culturing temperature of 37 degrees C and 33.3% at 55 degrees C. McNemar's test indicated a significant difference (p less than .03) in sterilization failures associated with the type and number of microorganisms present on the test strips. This study also showed that the more times a sterilizer was tested, the more likely a failure would occur. Overall, an alarming number of sterilizers (64.7%) were not effective in killing all the spores present on the indicator strips. When office personnel were given information for improving sterilizer performance, there was a noticeable reduction in sterilization failures following retesting.     

Compliance with infection control programs in private dental clinics in Jordan

The aim of this study was to assess the compliance of general dental practitioners (GDPs) in the private sector in North Jordan with infection control measures. A pilot-tested questionnaire about infection control measures was distributed in March 2004 to 120 private practices. The response rate was 91.66 percent. About 77 percent of dentists usually ask their patients about medical history, 36 percent were vaccinated against hepatitis B, 81.8 percent wear and change gloves during treatment and between patients, and 54.5 percent wear and change masks during treatment and between patients. Most dental practitioners (95.4 percent) reported that they changed extraction instruments and burs between patients. All dental practitioners reported that they changed saliva ejectors between patients, but only 41.8 percent changed handpieces between patients. Approximately 63 percent (69/110) used autoclaves for sterilization, 47.3 percent (52/110) used plastic bags to wrap sterilized instruments, and only 18 percent (20/110) disinfected impressions before sending them to dental labs. Fourteen percent used rubber dams in their clinics, and only 31.8 percent had special containers for sharps disposal. Based on these responses, approximately 14 percent of general dentists in this sample were considered to be compliant with an inventory of recommended infection control measures. In Jordan, there is a great need to provide formal and obligatory infection control courses and guidelines for private dentists by the Ministry of Health and the dental association in addition to distribution of standard infection control manuals that incorporate current infection control recommendations.     

Discharge of lubricant from air turbine handpieces

OBJECTIVE: To demonstrate and quantify the discharge of lubricating oil from high-speed air turbine handpieces whilst running. MATERIALS AND METHODS: Dye-marked oil (Kavospray, KaVo) was used to lubricate four handpieces (Quiet-Air, Midwest) and the air discharged from around the lower bearing was directed at the moving chart paper on a recorder whilst running for 40 minutes. Secondly, seven new handpieces (Quiet-Air, 300SE, Midwest; Topair 796, Topair 795, W+H; VIP-Sigma, Pana-air, NSK; Lares, Lares Research) were cleaned, weighed and then lubricated with unmarked oil (Kavospray, KaVo). Oil discharge was determined gravimetrically over runs of 240 minutes. Data were fitted to the logistic dose response function. RESULT: The dye-marked oil tests showed that oil was discharged for at least 40 minutes in the direction of the bur. The gravimetric tests showed that oil continued to be discharged up to at least 240 minutes, and that the usual practice of removing excess lubricant by running for 1-2 minutes was ineffective in preventing cut-surface contamination. SIGNIFICANCE: Bonding procedures in dentistry may be jeopardised by oil contamination from handpiece lubricants. Decontamination with a detergent is suggested as a means of ensuring effective adhesive dentistry.