The management of dental waste in dental offices and clinics in Shiraz, Southern Iran

BACKGROUND

Dental waste can be hazardous to humans and the environment.

OBJECTIVE

To determine the current status of dental waste management in private and public dental clinics and private dental offices in Shiraz, southern Iran.

METHODS

This cross-sectional study was conducted at the Shiraz University of Medical Sciences from February through June 2013. A stratified random sampling method was used to study 86 private offices, 14 private clinics and 10 public clinics. Types of waste studied included mercury and amalgam, lead foil packets, sharps, infectious tissues and fluids, pharmaceuticals and domestic waste materials. Compliance with established standards by the monitored dental offices and clinics and public clinics were compared.

RESULTS

89.1% of dental offices and clinics disposed their infectious waste with domestic waste. Only 60% of centers used standard method for sharps disposal. None of the dental centers disposed their pharmaceutical waste and x-ray fixer waste by standard methods. Less than 10% of centers recycled the amalgam and lead foil pockets waste to the manufacture.

CONCLUSION

Government agencies should establish monitoring programs for all dental offices and clinics to identify noncompliant activity and enforce recommended regulations.

Blood contamination of used dental anesthetic cartridges

This study sought to determine the levels of blood contamination found in and/or on used dental anesthetic cartridges and to measure antibacterial effects after exposure to a local anesthetic solution. The study analyzed a total of 1000 used cartridges from an oral surgery clinic, containing 1 of 3 anesthetic types. Blood testing included visual observations (using a dissecting microscope) and chemical analyses. From each cartridge, either 0.5 ml of residual anesthetic solution or a combination of anesthetic solution plus added saline was removed. Using reagent strip dipsticks, the solutions were analyzed for minute amounts of blood. Visual examinations were scored on a positive or negative scale. In addition, 4 types of bacteria were mixed with lidocaine or phosphate buffered saline (PBS) for up to 30 days, and viable cell counts decreases were measured for the 2 solutions. A majority of the cartridges evaluated contained lidocaine, and while only 7 of the 1000 cartridges examined contained visible blood, the reagent strips detected blood in more than 76% of all cartridges. Lidocaine and PBS produced similar bacterial death rates. The authors concluded that blood contamination levels in the absence of pronounced antibacterial activity indicate that dental anesthetic cartridges could be considered a potential type of regulated medical waste.

Improving and monitoring autoclave performance in dental practice

The sterilisation of instruments is central to the infection control process in the dental surgery, with the autoclave being most frequently used for this process. For effective operation, among other factors, it is essential that the autoclave is loaded correctly and tested regularly to ensure that it is operating at a temperature and pressure which will kill all micro-organisms. Biological indicators are another method of verifying the sterilisation process, since the sterilisation of the bacterial spores within the test ampoule provides a guarantee that sterilising conditions have been achieved.

Antimicrobial activity of ultrasonic cleaners

This study assessed the antimicrobial activity of two cleaning solutions and tap water after varying periods of use in one ultrasonic cleaner. Testing involved filling the cleaner's tank and a centred glass beaker with the same test solution. An aluminium foil strip test first determined that no significant differences in cavitational activity existed inside the beaker compared with outside. Standardized solutions of Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella choleraesuis were left at room temperature for 10 min. Aliquots were exposed to both cleaning solution and ultrasonic action. Unused test solution was removed from the tank, filter-sterilized, mixed with bacterial suspension and placed into a sterile beaker. Cleaning was allowed for 10 min. The beaker was removed and its contents examined. The tank was allowed to cool for 30 min and the process was repeated four times. The entire experimental set was repeated once. Exposure to test solution alone in all but one case produced reductions in bacterial numbers from initial >/=2 x 10(9) by 19.9-52.6%. Application of both chemical exposure and ultrasonic cleaning produced greater bacterial kill (46.4-99.7% reductions). However, kill became less effective on repeated use of a commercial cleaning solution. Reduction was highest when fresh ultrasonic cleaning solutions were used. In no case did complete sterilization occur. As well as removing adherent material, ultrasonic cleaning may also markedly reduce the number of viable organisms present.

The incidence of occupational exposures among students in four UK dental schools

OBJECTIVES

To evaluate: the incidence of occupational exposures (OE) to patient body fluids among a sub-group of dental students; the rate of reporting of incidents; and the association of various factors.

DESIGN

Multicentre retrospective analysis.

SETTING

Four UK dental schools in 2000.

SUBJECTS

Dental students from 4 UK schools completed a confidential questionnaire at the end of the clinical years of their undergraduate course.

RESULTS

The response rates ranged from 71-100%, showing that 12-40% of students among the schools had experienced one or more OE incidents since starting their course. No statistically significant association was found between OE incidence and age, sex, dominant hand or time of day; most OE occurred with handling of local anaesthetic syringes. 61-78% of incidents were penetrative in nature, and 28-53% of students had not reported their last OE. OE incidence was associated with school, year of course, presence of patient and presence of an assistant. There were substantial differences in the numbers of students experiencing OE among the schools.

CONCLUSIONS

Within the limitations of the survey and variations within the clinical activity of schools, it may be seen that improvements are needed in some schools to reduce cross-infection risks, and increase reporting of incidents. Suggestions are offered which may increase the safety of dental treatment.

Occupational exposures occurring in students in a UK dental school

BACKGROUND

Students whilst training may encounter a number of incidents where infection from patient body fluids may occur, especially as their manual skills are underdeveloped and their clinical experience is limited.

PURPOSE OF STUDY

(a) To assess the nature of the occupational exposures occurring to students in a UK dental school, (b) to assess the rate of reporting of incidents, and (c) to evaluate the association of various factors with these exposures. Students in the third, fourth and final years of the 5-year undergraduate dental course at the University of Birmingham were asked to complete a questionnaire that inquired into personal details, number and nature of incidents, their reporting and follow-up. A 100% response rate was achieved.

RESULTS

Across the years, there was no significant correlation (p > 0.01) between sex, dominant hand, use of protective glasses or time of day. Slightly more exposures occurred in males, right-handed students, and in the afternoon. A significant decrease in exposures (p < 0.01) occurred within final year, and when an assistant was employed. Significantly more incidents occurred while a patient was being treated than during operational clean-up procedures. A substantial number of dental students had experienced one or more occupational exposures during training. Of these, percutaneous injuries predominated. Junior students appear to be more likely to experience exposures, and in these students, needlestick injuries are the most common source.

CONCLUSIONS

To reduce the incidence of these exposures, more instruction and training may be required in the earlier clinical years and more chairside assistance. Improvements are required in the monitoring of post-screening for seroconversion after HBV immunization, and in the reporting of test results in the event of an exposure incident. Under-reporting of incidents is common and ways to encourage and facilitate reporting should be sought.

Dental instrument sterilization: a six-step process

The recycling of orally soiled dental instruments and pieces of equipment involves a collection of procedures that prepare those items for reuse. The process must be performed properly each time - so, that patients and dental office staff are not placed at risk. For the sterilization effort to be successful, it must also be efficient and as benign as possible to items being treated. The overall process involves six basic steps. The procedures involve a smooth step-to-step flow and a dedicated location. The ideal flow is as follows: (1) receive dirty items at designated "dirty area, (2) move to soaking (holding) area, (3) move onto scrubbing/ultrasonic (cleaning) area, (4) move onto packaging, (5) sterilize, and (6) finally storage and distribution.

Strategic planning for infection control

Proper infection control procedures help to protect dental practitioners, patients, and the surrounding community. The two basic goals of dental asepsis are simple and straightforward: minimize the spread of potentially pathogenic microorganisms and neutralize organisms that have contaminated dental instruments, equipment, and other office environmental surfaces. Meeting these goals, however, can be complicated. A valuable tool would be the generation and maintenance of a written set of infection control procedures ("an office infection control manual"). One way to organize a procedures manual is to arrange required tasks in response to specific pathways of cross-infection. Also, the effectiveness of an infection control program can be positively affected by office design.

Cleaning dental instruments: measuring the effectiveness of an instrument washer/disinfector

PURPOSE

To analyze the cleaning effectiveness of one type of instrument washer available for use in a dental office.

MATERIALS AND METHODS

Dental instruments were heavily contaminated with blood and specific test bacteria. They were placed in cleaning baskets or within instrument cassettes, processed through the instrument washer, and analyzed for remaining blood and viable bacteria.

RESULTS

Information obtained indicated that the washer is an effective cleaning system for dental instruments.

Strategies for dental clinic infection control

The application of proper infection control procedures helps to protect practitioners, patients and the community. The goal is to minimize the spread of potentially pathogenic micro-organisms and to remove and/or kill organisms that have contaminated objects and surfaces. Dental practitioners are aided in this process by the generation of rules, guidelines and recommendations by regulatory agencies and professional organizations. Ideally, each office/clinic would generate and maintain a written set of infection control procedures.

Moving towards a latex-free environment: advice from experiences in US dentistry

Most dental practitioners now routinely wear gloves while treating patients. The most commonly used types of gloves contain latex. Latex is also present in other personal protective equipment, such as masks, eyewear and clinic gowns. Increased use of such items, unfortunately, has been linked to adverse skin and mucous membrane reactions. Latex proteins and chemicals associated with the material's production have been implicated. Exposure to such chemicals has also resulted in allergic responses in dental patients. There is a strong movement in the USA to limit exposure to latex in healthcare environments, including dentistry. The aim of this article is to describe past, present and future efforts to create low-latex or latex-free environments.

Infection control practices and compliance to national recommendations among dentists in Romania

The aim of this study was to measure dental office compliance with current Romanian infection control regulations. A questionnaire was completed and returned from 61 randomly selected offices (32 private and 29 public with 94 dentists), where the sterilizers were also biologically monitored. Results indicated that with few exceptions, infection control practices in public and private offices were the same, with compliance on sterilising reusable instruments. Private offices monitored their sterilizers more frequently and had much newer equipment. Gowns were universally worn, but use of gloves, masks and protective eye-wear showed non-compliance with less than 10 per cent of the offices using personal protective equipment for all patients. Cost was the deciding factor. Predominant environmental disinfectants were alcohol and bleach. Offices were in compliance as to the use of disposable anaesthetic needles and carpules. Dentists reported reluctance to be vaccinated against hepatitis B even when offered free immunizations (6.4 per cent) and only 18.1 per cent of dentists had received any infection control training in the last three years. Results indicate that offices were in compliance for most national regulations. However, there are no recently published standards for dentistry in Romania concerning disinfectants or continuing education. Comparison with the literature indicates comparable compliance with recommended national infection control procedures for Romanian dentists as for dentists in other countries.

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.

Human hepatitis viruses

Dental care workers, including dental laboratory technologists, are at occupational risk for the occupational acquisition of hepatitis viruses. Of course, personal behaviors, home environments and health histories affect the rate of viral infections for all persons. Of greatest concern are hepatitis B, C and D. Although highly infectious, there are highly effective vaccines that prevent acquisition of hepatitis B. Prevention of hepatitis B infection precludes any hepatitis D infection. Hepatitis C viruses are less infectious than hepatitis B. However, since no vaccine exists for hepatitis C and the increased chances for the development of chronic infection hepatitis C will remain a serious health concern. Human blood is an excellent medium for the growth and transmission of human hepatitis. This means that new (and possible more virulent forms of currently known viruses) hepatitis viruses will likely continue to be identified for the foreseeable future.

Antimicrobial activities of dental impression materials

OBJECTIVE

The aim of this study was to measure the in vitro killing effects five commercial alginate impression materials had on five test microorganisms.

METHODS

Two alginates with no added disinfectant, one supplemented with chlorhexidine and two others containing quaternary ammonium compounds were tested. Challenge microbes included two gram-positive cocci, two gram-negative bacilli and a yeast. Saline solutions containing standardized concentrations of test microbes were used to mix the alginates. Some set specimens were immediately homogenized and the resulting fluids diluted and spread plated. Other specimens were processed 30 or 60 min after setting. After culturing, the numbers of colonies were counted and the levels of microbial reductions determined.

RESULTS

Unsupplemented alginates had no antimicrobial effects. The quaternary-ammonium-containing alginates were completely effective against all five test microorganisms. The alginate with chlorhexidine killed all the gram-negative bacilli and the majority (95-99%) of the gram-positive cocci and yeast.

SIGNIFICANCE

Results indicated that disinfectant-containing alginate impression materials could reduce the number of soiling microorganisms present on and within test specimens.

Effect of ultrasonic cleaning on microorganisms

PURPOSE

To establish a method to measure microbial kill caused by ultrasonic cleaning. Secondarily, to estimate the escape of bacteria from the ultrasonic cleaning solutions during operation of the unit.

MATERIALS AND METHODS

Three commercial enzymatic detergents and saline were used as cleaners. Depending on detergent, initial operational temperature was 21 degrees C, 37 degrees C or 60 degrees C. Streptococcus mutans ATCC 25175 (S. mutans suspensions) was adjusted to a final concentration of 1.0 x 10(3) cells/mL in saline. Suspensions (2000 mL) at the desired temperatures were added to the cleaner. Aliquots were removed, serially diluted in letheen broth and spread plated over mitis salivarius agar. Appropriate amounts of detergent solutions were added to S. mutans suspensions and the cleaner operated for 20 minutes. Aliquots were then removed and plated. The process was repeated twice. Plates were aerobically incubated at 37 degrees C for 7 days and the colonies counted. The procedure was repeated using three temperatures of S. mutans suspensions (21 degrees C, 37 degrees C or 60 degrees C), but without detergent or ultrasound. Also, detergents were added to 21 degrees C S. mutans suspensions and allowed to sit for 20 minutes without ultrasonic cleaning. Microbial sampling was done as previously described.

RESULTS

Results when ultrasound was used indicated that little kill (5-15%) occurred in 21 degrees C or 37 degrees C detergent solutions. Greater kill (25-35%) was noted with 21 degrees C and 37 degrees C saline. Complete kill was accomplished with 60 degrees C saline or the 60 degrees C detergent solution. When ultrasound and detergent were not used, there was no kill in 21 degrees C and 37 degrees C saline, but complete kill in 60 degrees C saline. In the absence of ultrasound no kill was noted in 21 degrees C S. mutans suspensions to which detergent had been added. Total kill of S. mutans was observed in 60 degrees C saline or 60 degrees C detergent with ultrasound or after a 20-minute exposure in 60 degrees C saline without ultrasonic cleaning. Very few bacteria escaped from the ultrasonic cleaning solutions into the air during the cleaning process. Placement of the unit lid effectively reduced emissions to zero.

Autoclave performance and practitioner knowledge of autoclave use: a survey of selected UK practices

OBJECTIVE

It is essential that the dental surgery autoclave be tested regularly to ensure that it is operating at a temperature and pressure that will kill all microorganisms. The aims of this study were to investigate the knowledge of general dental practitioners on aspects of autoclave use, to examine their autoclaving routines, and to test the effectiveness of the sterilization cycle of their practice's autoclave.

METHOD AND MATERIALS

A 35-question questionnaire was distributed to 840 dental practitioners in the United Kingdom. They were also sent three spore test ampules with details of their function and instructions on their use. The practitioners were asked to use the spore test ampules in their own practice's autoclave and to return these for testing.

RESULTS

Four hundred one questionnaires and associated spore test ampules were returned for analysis, a 47.7% response rate. Eight practice autoclaves (2.0%) failed to sterilize the spores. These practices were offered a retest following counseling. A total of 77.8% of respondents had received formal training in infection control. Of the 71.3% of respondents who stated that they check the performance of their autoclave routinely, 31.5% use a chemical strip every cycle, 17.5% use it once per day, and 30.4% use it once per week. However, only five respondents (1.2%) use a spore test; two of these respondents use it every cycle, one once per day, and two once per week.

CONCLUSION

Further education of practitioners may be necessary to enhance their awareness of the need for routine checking of autoclave effectiveness.

Latex exposure and allergy: a survey of general dental practitioners and dental students

Gloves are now worn routinely by most general dental practitioners and dental students while treating patients, with latex being the most commonly used glove material. By means of a questionnaire, this study surveyed 160 students in one dental school and 300 randomly selected general dental practitioners in respect of their exposure to latex. Response rates were 74.4 per cent and 57.3 per cent for dental students and practitioners respectively. Adverse skin reactions to the wearing of latex gloves was reported by 18.5 per cent of dental students and 22.8 per cent of practitioners. Analysis of the data indicated that there was an association between student year and adverse skin reaction to latex, an association between years in dental practice and adverse skin reaction to latex and a strong relationship between dentist's gender and adverse skin reaction to latex. Respondents who suffered from eczema or food allergies were more likely to have experienced an adverse skin reaction to latex glove wearing. It is concluded that adverse reactions to latex occur in significant numbers of dental students and dental practitioners, with those who reported personal and familial atopy being more likely to be affected.

Eye protection in dental laboratories

Many dental laboratory procedures increase the chances of serious eye injury. This would include traumatic injuries due to projectiles or through exposure to harsh chemicals or heat and infections from contact with patient body fluids. To help assure a safer working environment, awareness of the need for eye protection must be established and maintained by all laboratory personnel. The purpose of this article are: 1) to list the applicable federal regulations concerning eye safety in dental laboratory workplaces; 2) to describe the various types of appropriate eyewear; and 3) to identify which protective devices best prevent exposure to specific types of hazards. The goal of this article is to help dental laboratories with their employee safety programs, especially concerning the selection of protective eyewear. Such programs must include engineering controls and work practice controls plus appropriate personal protective equipment. Laboratories today must comply with safety mandates in the most effective and efficient manner.

Sterilization of slide sheath anesthetic injection systems placed within sharps containers

The purpose of this study was to evaluate the effect that two steam autoclaves and an unsaturated chemical vapor sterilizer had on killing bacterial endospores present on commercial spore strips or applied to sterile anesthetic injection systems placed within sharps containers. Three types of sterilizers were used: a gravity steam autoclave, a high vacuum steam autoclave and an unsaturated chemical vapor sterilizer. The microbial challenge for the sterilizers were Bacillus stearothermophilus spores present on commercial spore strips or drawn into and applied onto sliding sheath anesthetic injection systems with anesthetic carpules attached. Spore-soiled items were placed into the middle of sharps containers three-quarters-filled with representative clinical waste and sterilized. If, after culturing, sterilization of all test items in a group was not achieved, additional sterilization time was applied. Spore strips were killed within a single cycle of each sterilizer. Spore-soiled injection systems and carpules could not be routinely sterilized in the gravity steam autoclave or unsaturated chemical vapor sterilizers, even after three consecutive sterilization cycles. These items, however, were sterilized by exposure to a single-treatment cycle in a high-vacuum steam autoclave. Results indicate that routine sterilization of spore contaminated anesthetic carpules or injection systems could not be accomplished in a reasonable amount of time using sterilizers commonly found in dental offices.

Antimicrobial abilities of various dentine bonding agents and restorative materials

OBJECTIVES

The purpose of this study was to observe and measure the in vitro effect of various composite restorative materials and dentine bonding agents on the growth and adherence of oral bacterial believed to be responsible for recurrent caries in humans and on micro-organisms commonly used to evaluate the effectiveness of disinfecting agents.

METHODS

Five sets of dentine bonding agents and composite resins and ten species of micro-organisms were used. Circular disc specimens of each composite set were placed onto inoculated plates. Zones of growth inhibition around specimens were measured after incubation. On other plates, specimens were placed alone for 48 h, removed, and then the micro-organisms added. Also, the composite sets were placed into sterilized bovine incisors and suspended into sucrose-containing both inoculated with Streptococcus mutans for 3 days. Adhering materials were disclosed and scored.

RESULTS AND CONCLUSIONS

Four of the composites sets produced statistically similar (P > 0.05) inhibitory zones. The Gram-negative rods and the Staphylococcus aureus were the most resistant micro-organisms. The five composites sets produced the same (P > 0.05) reduction in bacterial accumulation (> 60%). Aging of the specimens in water for periods up to 4 weeks prior to exposure to S. mutans did not affect product activity.

Effectiveness of three types of sterilization on the contents of sharps containers

The purpose of this study was to test the effect of treatment in a gravity steam autoclave, high-vacuum steam autoclave, or an unsaturated chemical vapor sterilizer on endospores present on strips or placed inside of dental anesthetic cartridges held within sharps containers. Strips with 1.7 X 10(5) Bacillus stearothermophilus endospores were used; the cartridges were soiled with an equal number of spores or spores mixed with blood. If sterilization was not accomplished after the initial period, additional exposure time was added. Neither the presence of blood or anesthetic solution nor the position of the container affected the efficiency of sterilization. Soiled cartridges were much more difficult than strips to sterilize. Intact cartridges could not be sterilized by two runs in a gravity steam autoclave or an unsaturated chemical vapor sterilizer or one run in a high-vacuum steam autoclave. Sterilization occurred after two runs in the gravity steam autoclave and unsaturated chemical vapor sterilizer only when one end of the cartridge was removed prior to processing. Results indicated that unopened spore-soiled cartridges are not readily sterilized by commonplace office sterilizers, even after extended exposure.

Effectiveness of two types of sterilizers on the contents of sharps containers

The purpose of this study was to evaluate the killing effect that a gravity steam autoclave (GSA), a high-vacuum steam sterilizer (HVA) or an unsaturated chemical vapor sterilizer (UCV) had on endospores present on strips or applied to dental needles within three sizes of sharps containers. Commercial spore strips containing 1.7 x 10(5) Bacillus stearothermophilus endospores were used, while the needles were soiled with an equal number of spores or with spores mixed with blood. Needles were tested capped and uncapped. Initial operating conditions were for the: (1) GSA were 129 kPa at 124 degrees C for 30 minutes; (2) HVA were 214 kPa at 131 degrees C for 10 minutes and (3) UCV, 172 kPa at 134 degrees C for 20 minutes. Strips and needles were placed within 3/4 filled containers. Fill materials consisted of needles, syringes, plastic sheaths and scalpel blades. Containers were processed upward or on their sides. Twenty-five strips or needles comprised a test group for each operational parameter. Processed strips and needles were aerobically cultured at 56 degrees C for 7 days. If sterilization was not accomplished after the initial period, additional exposure time was added. Results included: (1) soiled needles are more difficult than strips to sterilize; (2) capping or the presence of blood did not affect sterilization efficiency; (3) container positioning was important only for the smallest container; (4) additional exposure time was usually required when sterilizing soiled needles; (5) the HVA killed all spore challenges in a single sterilization cycle and (6) GSA and UCV were approximately equal in sterilization efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of steam sterilization on the contents of sharps containers

BACKGROUND

One form of medical waste known to be capable of transmitting disease is the contaminated sharp. Safe handling and disposal of sharps is an essential element of any infection control program. Many areas allow the on-site treatment of sharps containers. However, little information currently exists as to the most effective sterilization procedures and container designs.

METHODS

This study was intended to evaluate the effect treatment with various autoclaves had on bacterial endospores present on strips or needled syringes. Strips contained 1.7 x 10(5) Bacillus stearothermophilus spores; syringes were soiled with equal numbers of spores or with spores plus blood. Syringes were tested capped and uncapped. A gravity-displacement autoclave and a high-vacuum autoclave were used. Strips and syringes were placed within sharps containers three quarters filled with representative materials. Six types of containers were tested. Containers were processed sitting up or on their sides. Processed strips and needles were aerobically cultured at 56 degrees C for 7 days. If sterilization was not accomplished initially, additional exposure time was added.

RESULTS

(1) Soiled syringes were more difficult to sterilize than strips. (2) Capping or the presence of blood did not affect sterilization efficiency. (3) Container positioning was important only for the gravity-displacement autoclave. (4) Additional exposure time was required in the gravity displacement autoclave when sterilizing soiled syringes but not strips. (5) High-vacuum autoclaving killed all spore challenges within the normal processing interval.

CONCLUSIONS

The data indicate that processing of sharps containers within a gravity-displacement autoclave appears to require extended exposure intervals to achieve sterilization.

Inhibition of microbial adherence and growth by various glass ionomers in vitro

This study measured the in vitro inhibition of growth and adherence of five oral bacteria by glass-ionomer materials. Disks were prepared from two cavity liners and four restorative class materials, by use of Teflon plates with circular wells, five mm wide and two mm deep. The bacterial species tested included: A. viscosus, S. mitis, S. mutans, L. casei, and S. sanguis. Growth inhibition studies were performed by the spreading of 0.1 mL of standardized inocula over agar plates produced with selective media, followed by the direct application of glass-ionomer disks onto the agar. On other plates, disks were placed onto uninoculated agars for 48 h, followed by bacterial inoculation. All agar plates were incubated under optimal growth conditions for each bacterial species. The four restorative materials were also placed aseptically into sterilized bovine incisors and placed into sucrose containing broth media, inoculated with S. mutans for three days. Adhering materials were disclosed and scored. An ion-exchange electrode was used to measure fluoride release over a seven-day period for all six glass ionomers. The two cavity liners and two of the restorative materials produced the largest growth inhibition zones by direct contact. No growth inhibition occurred when the specimens were allowed to come into contact with the agars prior to inoculation. All four restorative materials reduced bacterial accumulations on enamel surfaces by over 80%. Elevations in short-term fluoride release levels were positively correlated with growth inhibition.

Effectiveness of steam sterilization on the contents of sharps containers

The purpose of this study was to evaluate the killing effect that treatment in gravity or high-vacuum steam autoclaves had on endospores present on strips or applied to dental needles within 10 types of small sharps containers. Spore strips containing Bacillus stearothermophilus endospores were used, while needles were soiled with an equal number of spores or with spores mixed with blood. Needles were tested capped and uncapped. Strips and needles were autoclaved in empty and 3/4 filled containers placed in several orientations (vents open or closed, upward or on-side). If sterilization was not accomplished within the initial period, additional exposure time was added up to a one hour maximum. Major findings for gravity autoclaves were: 1) strips and needles present in empty containers could, in most cases, be sterilized within 15 minutes when the vents were left open and the containers were placed on-side; 2) spore- and spore plus blood-soiled needles were more difficult to sterilize then were commercial spore strips; 3) capping of needles and the presence of blood did not decrease sterilization efficiency; 4) sterilization in the presence of fill material required additional exposure times and 5) larger containers (greater than 500 ml volume) were more difficult to sterilize than were the smaller (250 ml) ones. All type of open-vented, filled containers could be sterilized within 10 minutes in a high-vacuum autoclave.

Treatment and disposal of contaminated sharps

Dentists, like other health care workers, make an overt effort to protect themselves and their employees from infectious agents present in the body fluids of their patients. Of special concern are treatment-generated infectious waste materials, such as sharps. Sharps are items such as needles, sutures, scalpel blades, or broken glass which are capable of puncturing, cutting, or abrading tissue. Needles can cause occupational transmission of hepatitis B and AIDS. This article presents methods to safety store, treat, and dispose of sharps. All suggested procedures comply with current Indiana law, CDC guidelines, and EPA and OSHA regulations.

Effectiveness of steam autoclaving on the contents of sharps containers

The effectiveness of steam autoclaving on bacterial endospores placed within five types of sharps containers was tested. A variety of container physical orientations within the autoclave were evaluated. Spores were present on commercial spore strips or placed onto capped and uncapped dental needles. All strips and needles present in empty or filled containers could be sterilized within 15 minutes when the containers were placed on their sides and their vents left open. The contents of containers processed in an upward position required between 30-60 minutes of autoclaving before being sterilized. The size and shape of the containers influenced ease of sterilization.