Dry Heat Sterilization Research Articles

Effect of steam versus dry-heat sterilization on the wear of orthodontic ligature-cutting pliers

The purpose of this study was to compare the wear of orthodontic ligature-cutting pliers after multiple cycles of cutting stainless steel ligature wire (.025 mm) and sterilizing with dry heat or steam autoclave. Fifty ligature-cutting pliers with stainless steel inserts were randomly divided into 2 equal groups to be sterilized in either dry heat or steam autoclave. Each plier was subjected to a series of ligature wire cuts followed by the assigned sterilization method. The amount of wear at the tip of each plier in both groups was measured with a stereo microscope system and digital photomicrography. Wear was defined as the difference in initial length from a marked reference line to the tip of the plier minus the length after 6 and 12 cycles of use and sterilization. There was no significant difference in the mean wear at the tip of the pliers between the 2 groups. It appears that there is no need to maintain both sterilization systems, dry heat and steam autoclave, in the orthodontic office. Steam autoclave sterilization can be used with no deleterious effects on the pliers if they are manufactured with stainless steel inserts. (Am J Orthod Dentofacial Orthop 2002;121:467-71)

Uso y verificación con indicadores biológicos en esterilizadores de cirujanos dentistas de San Luis Potosí, México

To assess the utilization of sterilizing equipment used by dentists, and verification of sterilization using biological indicators.A cross-sectional study was conducted in 1999-2000, among 130 (65%) dentists having sterilizing equipment, at Facultad de Estomatología, Universidad Autónoma de San Luis Potosí and Colegio Dental Potosino. Biological indicators for sterilization containing Bacillus subtilis and Bacillus stearothermophilus were used.Thirty autoclaves and 100 dry-heat sterilizers were evaluated: 23 (17.7%) of them showed bacterial growth. Twenty-one (16.1%) dentists already were using biological indicators to verify their sterilizing equipment. Both sterilization methods were found to allow bacterial growth with similar frequencies (p = > 0.66).Few dentists verify the quality of sterilization process through biological indicators; bacterial growth and failure of sterilization were evidenced.

Influência do eugenol na microdureza da resina composta utilizando sistemas adesivos atuais

O objetivo deste trabalho foi avaliar, in vitro, se a utilização do cimento de óxido de zinco e eugenol exerce influência na microdureza da restauração de resina composta (Z100) realizada com dois sistemas adesivos (Scotchbond Multi-Purpose Plus® - sistema que remove o "smear layer", e o Clearfil Liner Bond 2® - adesivo que promove o tratamento do "smear layer", sem removê-lo totalmente). Para isto, foram utilizados 40 molares humanos hígidos que foram divididos igualmente em 4 grupos. Para cada adesivo havia um grupo controle (sem óxido de zinco e eugenol) e outro onde foram realizadas e removidas as restaurações provisórias com cimento de óxido de zinco e eugenol. Após sete dias de armazenamento em estufa a 37ºC, os dentes foram cortados e mediu-se a microdureza da resina composta na região a 0,3 mm da interface dente-restauração em um microdurômetro SHIMADZU HMV 2000, com ponta penetradora Knoop de 50 gramas por 45 segundos. Os resultados obtidos foram analisados estatisticamente pela ANOVA (alfa = 1%), e verificou-se não haver diferença estatisticamente significante na microdureza da resina composta entre os grupos estudados.

Survey on attitudes toward HIV-infected individuals and infection control practices among dentists in Mexico City

Background: The teaching of infection control is gradually being introduced at dental schools in Mexico. However, most practicing dentists have limited access to current infection control standards. Deficiencies of knowledge with regard to blood-borne pathogens such as HIV and hepatitis B virus may influence attitudes toward infected individuals and reduce compliance with infection control recommendations.Objective: The purpose of this study was to assess (1) attitudes toward HIV-infected patients and hepatitis B virus-infected patients and (2) infection control knowledge and practices among dental practitioners in Mexico City.Method: A total of 196 dentists were interviewed by means of a questionnaire with Likert-type scales and open-ended questions (response rate, 86.1%).Results: Most respondents had no previous social or professional contact with HIV-positive individuals. Nine percent indicated that they had knowingly treated HIV-positive patients. Perceived professional and moral obligations to treat HIV-positive patients were high. Thirty-five percent of the respondents perceived the risk of HIV infection as “considerable” to “very strong.” The risk of hepatitis B infection was considered significantly higher than the risk of HIV infection (P < .01); however, 78% of the respondents had not been immunized against hepatitis B. Reported use of personal protective equipment was high. Most respondents used dry heat sterilization. The principal disinfectants used were quaternary ammonium compounds, bleach, and glutaraldehyde. Fifty-four percent of the respondents acknowledged that clinical precautions reduced occupational risks.Conclusions: This survey revealed contradictory attitudes toward HIV-positive individuals and limited understanding of infection control recommendations. Educational and regulatory efforts are needed to promote better adherence to current infection control standards.

Effects of sterilization processes on NiTi alloy: surface characterization.

Sterilization is required for using any device in contact with the human body. Numerous authors have studied device properties after sterilization and reported on bulk and surface modifications of many materials after processing. These surface modifications may in turn influence device biocompatibility. Still, data are missing on the effect of sterilization procedures on new biomaterials such as nickel-titanium (NiTi). Herein we report on the effect of dry heat, steam autoclaving, ethylene oxide, peracetic acid, and plasma-based sterilization techniques on the surface properties of NiTi. After processing electropolished NiTi disks with these techniques, surface analyses were performed by Auger electron spectroscopy (AES), atomic force microscopy (AFM), and contact angle measurements. AES analyses revealed a higher Ni concentration (6-7 vs. 1%) and a slightly thicker oxide layer on the surface for heat and ethylene oxide processed materials. Studies of surface topography by AFM showed up to a threefold increase of the surface roughness when disks were dry heat sterilized. An increase of the surface energy of up to 100% was calculated for plasma treated surfaces. Our results point out that some surface modifications are induced by sterilization procedures. Further work is required to assess the effect of these modifications on biocompatibility, and to determine the most appropriate methods to sterilize NiTi.

Nurses and hospital infection control: knowledge, attitudes and behaviour of Italian operating theatre staff

This study examined the disinfection and sterilization practices used by hospital operating theatres and evaluated the knowledge, attitude and behaviour of nursing staff with regard to infection control. Of the 216 nurses responding, knowledge concerning such practices was not consistent since 10% did not believe that items should be rinsed in water after contact with glutaraldehyde and more than 25% thought that 10 min contact time provided sterilization. Almost all were aware that improper practices increased the risk of nosocomial infections in patients. Nurses in orthopaedic surgery had a significantly lower level of knowledge compared with others. The great majority of nurses agreed that guidelines for disinfection and sterilization practice should be maintained and applied. With regard to the use of surgical instruments, the majority used steam or dry heat sterilizers for the appropriate time and temperature. Glutaraldehyde was used by 95% to sterilize endoscopes, but at different temperatures and times of exposure. Similar procedures were reported as used for laryngoscopes, though a higher percentage used heat sterilization. Only 38% routinely used all barrier techniques (gloves, masks, and protective eye-wear). Predictors for the routine use of all barrier techniques included attendance at continuing education courses on nosocomial infections, and nurses who were male and those involved in orthopaedic operations. Data support the need for finding and implementing interventions related to the prevention of hospital infection activities, in order to motivate nurses to use the correct procedures as a routine.

Modelling the change in colour of potassium sorbate powder during heating

Colour change of potassium sorbate caused by heating was statistically modelled to examine its potential as a time–temperature process indicator. A full factorial design with five levels of heating time (t) and temperature (T) was used. L, a and b values were measured by a HunterLab colorimeter, and second‐order polynomial models were developed. Heating significantly reduced L and increased b values, causing the potassium sorbate powder to turn dark yellow, possibly because of non‐enzymatic browning reactions. Statistically significant models with good fit were developed for L and b, and their response surfaces were generated. This potassium sorbate‐based system may be a suitable indicator for high‐temperature heating processes such as dry heat sterilizers or baking ovens.

Effect of passivation and dry heat-sterilization on surface energy and topography of unalloyed titanium implants

The effects of nitric acid passivation (P) and dry heat-sterilization (S) on the surface topography and energy of unalloyed titanium were examined. Surfaces were treated using the following sequences: cleaned in phosphoric acid (C), C and passivated (CP), CP and dry heat-sterilized (CPS), CPS and resterilized (CPSS), and C and dry heat-sterilized (CS). Surface roughnesses were examined with atomic force microscopy (AFM) and mechanical profilometry. Critical surface tensions γ c and solid surface tensions γ t were determined from contact angles of distilled water and diiodomethane. Analysis of micro-roughness using AFM revealed no statistically significant differences among most roughness parameters for the various treatment conditions. However, the CS samples had a lower ratio of real to projected surface area. Macro-roughness analysis using mechanical profilometry showed that CPSS had lower peak count (PC, i.e. number of peaks above the mean line) values than CP and CS; PC values for C surfaces were also lower than CS. Also, CPSS had higher macro- R q values than C and CPS. Values of γ c correlated positively with the non-polar/dispersive components of γ t; values were highest with the CS specimens. Higher γ t values were found for the CPSS and CPS treated surfaces, reflecting greater polar contributions on these surfaces. Thus, P and S together resulted in increased surface energy, which is thought to be a desirable surface property for bone implants.

Effect of heat sterilization on the torsional properties of rotary nickel-titanium endodontic files

The purpose of this study was to determine whether heat sterilization adversely effects the torsional properties of rotary nickel-titanium files, making them more prone to fracture under torsional stress. Nine hundred sizes 2 through 10 Profile Series 29.04 taper files were divided into groups of 10 files each and sterilized 0, 1, 5, or 10 times in the steam autoclave, Statim autoclave, or dry heat sterilizer. Then, they were subjected to torsional testing in a Torquemeter Memocouple. Complete data were collected for sizes 2 through 7, but not for sizes 8 through 10 because their torque resistance exceeded the testing limits of the Torquemeter Memocouple. A one-way analysis of variance was used to compare all experimental groups in sizes 2 through 7 with their unsterilized controls (p < 0.05). Fifty-four comparisons were made for torsional strength and 54 for rotational flexibility. Ten significant changes occurred for torsional strength and 10 for rotational flexibility. Eight of 10 changes in torsional strength were increases. Fifty-two of 54 (96.3%) comparisons for torsional strength and 47 of 54 (87%) for rotational flexibility showed a significant increase or no change. Therefore, heat sterilization of rotary nickel-titanium files up to 10 times does not increase the likelihood of instrument fracture.

Disinfection and sterilization practices in Mexico

We evaluated antisepsis, disinfection, and sterilization procedures at 22 hospitals in the state of Yucatan, Mexico, which provide services for approximately 80% of the population. The percentage of hospitals that followed standard recommendations for diverse antisepsis procedures were as follows: surgical scrub, 41%; surgical site preparation, 68%; central intravenous (iv) catheters, 61%; peripheral iv catheters, 86%; urinary catheters, 41%, and umbilical cord care, 5%. Inappropriate procedures typically involved the use of benzalkonium chloride and mercury compounds. Adequate sterilization procedures were observed for sharp surgical instruments in 9%, for blunt surgical instruments in 81%; for linen in 90%; for surgical brushes in 9%; for metal prostheses in 100%; for plastic prostheses in 57%; and for disinfection of endoscopes in 30%. The most common errors were the use of too short an exposure time in steam sterilizers or dry heat sterilizers, and the use of benzalkonium chloride as a sterilizing agent. Only 14% of hospitals used commercial spore preparations for autoclave monitoring. For the reuse of disposables, 50–94% of hospitals employed inappropriate sterilization or low-level disinfection procedures. Similar conditions are likely to exist in hospitals throughout the country. The establishment of strict regulations and hospital training programmes for disinfection and sterilization procedures, and the reuse of disposable devices is urgently needed in Mexico.

Dry Heat Sterilizers Seized

Dry Heat Sterilizers Seized

Achieving Sterility in Medical and Pharmaceutical Products

The Need for Sterility Sterility and Sterility Assurance Sterilization by Gamma Radiation Sterilization by Saturated Steam Dry Heat Sterilization and Depyrogenation Sterilization by Ethylene Oxide Sterilization by Filtration Aseptic Manufacture Maintenance of Sterility Parametric Release and Other Regulatory Issues

Standards Proposed for Hemodialyzers &amp; Dry Heat Sterilizers

Standards Proposed for Hemodialyzers &amp; Dry Heat Sterilizers

New American National Standards for Steam &amp; Dry Heat Sterilization

New American National Standards for Steam &amp; Dry Heat Sterilization

Israeli dentists: a survey of infection control office practices and care of medically compromised patients.

A survey was conducted by interviewing a randomly selected sample of practicing dentists in Israel in 1991. The aim of this study was to evaluate methods of infection control in current use and to learn about the access to care for medically compromised patients. One hundred seventeen dentists were interviewed. This group represented a majority of graduates from Israeli schools (66). With respect to infection control, only 28% of the population surveyed routinely uses gloves, but 43% use steam autoclave, and 70% use dry-heat sterilization. A very high percentage (87%) took a verbal medical history, while a small minority (27%) had their patients fill out a written questionnaire. Only occasionally was the name of the patient's physician requested or recorded, implying a flaw in interprofessional communications. Only 26% of the dentists said they would treat patients with hepatitis and/or AIDS. Only about half the dentists accepted patients on chemotherapy or radiotherapy or those who were taking anticoagulant drugs. Physical access for dental patients in wheelchair or stretcher was markedly limited, with referral to regional hospitals the routine for these patients.

Effect of sterilization on contaminated sponges

Sponges are routinely used as a storage medium for endodontic files during clinical practice; however, very little research has been done to determine the effectiveness of sterilization procedures for these contaminated sponges. The purpose of this in vitro study was to determine the efficacy of chemical vapor sterilizers (chemiclaves), steam pressure sterilizers (autoclaves), and dry heat sterilizers on laboratory contaminated sponges. Four different types of sponges were used in this study: a black, relatively nonporous sponge; a red, semiporous stationary sponge; a blue, endodontic sponge, and a yellow, common household sponge. Natural sponges were eliminated from the study, because their large pore size made them unsuitable as a storage medium for endodontic instruments. The sponges were divided into three groups: chemiclave, autoclave, and dry heat. Five samples of each sponge type were impregnated with biological indicating strips containing spores of Bacillus stearothermophilus. Each sponge was subjected to 25 cycles of sterilization. The spore strip indicator was inserted into the sponges at 1, 5, 10, 15, 20, and 25 cycles. The spore strip was cultivated in trypticase soy broth medium solution at 55 +/- 1 degree C for 7 days. At 7 days the culture vials were read for turbidity; its presence indicating a positive culture. The samples that were subjected to chemiclaving demonstrated positive cultures of 0.00%, 0.00%, and 30.00% and those to autoclaving 3.33%, 0.00%, and 0.00% positive cultures for the black, red, and blue sponge types, respectively. None of the sponges survived dry heat sterilization. The O-Cell-O sponges become unusable when subjected to all of the sterilization methods used in this study.

The effects of sterilization on the tensile strength of orthodontic wires.

The purpose of this study was to evaluate the effect of sterilization on the tensile strength of 0.016" beta-titanium, nickel titanium and stainless steel wires. Three common methods of sterilization--autoclaving, dry heat and ethylene oxide--were evaluated in three test trials involving zero, one and five sterilization cycles. For each of the test trials, five pieces each of 0.016" TMA, 0.016" Sentalloy and 0.016" Tru-chrome stainless steel wires were sterilized using a standard autoclave. Five other pieces of each of the same wires were sterilized in a dryclave, while an additional five pieces of each of the three wire types were sterilized using ethylene oxide. The ultimate tensile strengths of the wires were then determined using an Instron Universal Testing Machine. The data were compared for statistical differences using analysis of variance. The results showed that dry heat sterilization significantly increased the tensile strength of TMA wires after one cycle, but not after five cycles. Autoclaving and ethylene oxide sterilization did not significantly alter the tensile strength of TMA wires. Dry heat and autoclave sterilization also significantly increased the tensile strength of Sentalloy wires, but the mean strength after five sterilization cycles was not significantly different than after one cycle. Ethylene oxide sterilization of Sentalloy wires did not significantly alter the tensile strengths of that wire. There were no significant differences in the tensile strengths of the stainless steel wires following zero, one or five cycles for any of the sterilization methods.

Outbreaks of Hepatitis A and Emergence of New AIDS-Associated Agents: The Need to Add Terminal 100°C Dry-Heat Sterilization to Factor VIII and Factor IX Concentrates

Outbreaks of Hepatitis A and Emergence of New AIDS-Associated Agents: The Need to Add Terminal 100°C Dry-Heat Sterilization to Factor VIII and Factor IX Concentrates

A Novel Method of Sterilizing Orthodontic Instruments

Abstract A range of orthodontic instruments was artificially inoculated with a mixed culture of representatives of the oral microflora and a marker bacterium and subjected to dry heat sterilization using a glass bead sterilizer. The shortest time which would guarantee total sterilization of the functional parts of the instruments was thirty seconds.

Load-deflection characteristics of nickel-titanium alloy wires after clinical recycling and dry heat sterilization

The desirable mechanical properties of nickel-titanium alloy wires and their relatively high cost has prompted many clinicians to recycle these wires. Clinical recycling exposes the wires to several weeks or months of mechanical stresses and elements of the oral environment, as well as sterilization between uses. In a previous study it was noted that clinical recycling combined with cold sterilization alters the load-deflection characteristics and surface topography of nickel-titanium wires. Whether similar changes in mechanical properties occur in wires subjected to repeated clinical use and dry heat sterilization is not yet clear. The purpose of this investigation was to determine the effects of in vivo recycling interposed by dry heat sterilization (together referred to as clinical recycling, CR) on the load-deflection characteristics of nickel-titanium alloy wires. To differentiate the effects of dry heat sterilization (DHS) from those of CR on the behavior of these wires, a series of wires were also subjected to DHS only. Two types of nickel-titanium wires, namely Nitinol and NiTi were subjected to a three-point bending test in an as-received condition (T0), after one cycle (T1), and two cycles (T2) of DHS or CR. Ten wires comprised each subsample. Statistical analyses were done by one-factor repeated measures analysis of variance and Scheffe F test. Both DHS alone, as well as CR, produced significant changes in the loading and unloading characteristics of Nitinol and NiTi wires. However, the changes in the load-deflection characteristics of these wires after DHS only were relatively small, and the clinical significance of these changes is open to question.(ABSTRACT TRUNCATED AT 250 WORDS)