A comparison of decontamination methods used for dental burs

Biofilm on and structural damage of rotary cutting instruments after 5 cycles of clinical use and processing

BACKGROUND

Rotary cutting instruments (RCIs) are sterilized routinely. The authors aimed to analyze the structural integrity, presence of dirt, and microbial contamination of RCIs used in clinical practice after processing.

METHODS

Eighty-four RCIs (42 carbide burs, 42 diamond burs) were divided into baseline, control, and test groups. The RCIs were evaluated by means of scanning electron microscopy and microbiological analysis. Evaluation criteria included presence of structural damage, dirt, biofilm, and isolated cells and their phenotypic profile.

RESULTS

The carbide burs from all groups and diamond burs from the test groups had structural damage. Dirt was observed in the baseline and test groups. Three bacterial species were isolated from 4 RCIs (9.52%). An isolated cell was observed from 1 carbide bur. Biofilm was observed on 3 RCIs (7.14%).

CONCLUSIONS

RCIs should not be subjected to multiple uses; after the first clinical use they accumulate structural damage and dirt that hampers the cleaning step, causing failure in the sterilization process.

PRACTICAL IMPLICATIONS

The presence of microorganisms and structural damage on the RCIs confirmed that they are not amenable to processing, a fact that characterizes them as a single-use health care product.

Infection Control in Dental Clinics: Prosthodontics Perspectives

AIM

The aim of this article is to discuss the infection control measures with focus on those related to prosthodontic work.

BACKGROUND

The risk of transmission of several infectious microorganisms during dental procedures and the increased awareness and knowledge of infectious diseases have led to an increased attention to the importance of infection control. Prosthodontists and dental personnel are exposed directly or indirectly to a significant risk of acquiring healthcare-associated infections.

REVIEW RESULTS

High standards of occupational safety and dental infection control must be applied by dental personnel for the safety of patients and dental healthcare workers. All reusable items (critical and semicritical instruments) that come in contact with the patient's saliva, blood, or mucous membranes must be heat-sterilized. Proper disinfectants should be used to disinfect nonsterilizable instruments (e.g., wax knifes, dental shade plastic mixing spatula, guides, fox bite plane, articulators, and facebows).

CONCLUSION

In prosthodontics, items potentially contaminated with patient's blood and saliva are transported between dental clinics and dental laboratories. Such fluids may contain microorganisms with high potential for transmission of several diseases. Therefore, sterilization and disinfection of all items used during prosthodontic work should be part of infection control protocol in dental care setting.

CLINICAL SIGNIFICANCE

In prosthodontic practice, a strict infection prevention plan should be implemented to minimalize the risk of infectious diseases transmission among prosthodontists, dental office, dental laboratory personnel, and patients.

The Effects of Liquid Disinfection and Heat Sterilization Processes on Implant Drill Roughness: Energy Dispersion X-ray Microanalysis and Infrared Thermography

BACKGROUND

The aim of this study is to evaluate effects on stainless steel (SS) and zirconia implant drills of 50 cycles of sterilization through different processes.

METHODS

A total of 24 SS and 24 zirconia drills were treated with 3 different sterilization processes: 50 cycles of immersion in glutaraldehyde 2%, 50 cycles in 6% hydrogen peroxide and 50 cycles of heat. Energy-dispersive X-ray spectroscopy (EDX) was used to compare the effect of the different treatments compared to new untreated controls. Infrared thermography was used to measure the increase of temperature during drilling on bone ribs. A scanning electron microscopy (SEM) was used to measure the roughness of the samples.

RESULTS

Zirconia drills seem not to be affected by the different treatments; no significant differences were found with EDX nor through thermography controls. SS drills were affected by the different treatments, as confirmed by the increased roughness of the SS samples after all the cycles of sterilization/disinfection, measured at SEM. On the contrary, the zirconia drills roughness was not particularly affected by the chemical and thermal cycles. Significant differences were observed regarding the temperature, between steel and zirconia drills (p < 0.01).

CONCLUSIONS

The disinfection agents had a weak impact on the temperature changes during implant bone preparation, while heat sterilization processes had no effect on either of the drills evaluated. The disinfection agents increased the roughness of the steel drills, while they had no effect on the zirconia drills.

Contamination assessment of orthodontic bands after different pre-cleaning methods at a tertiary care hospital

INTRODUCTION

Infection control in dentistry is a major concern due to risk of transmission of communicable diseases. The aim of this study is to evaluate and compare the efficacy of various pre-cleaning methods for the tried-in orthodontic bands.

MATERIAL AND METHODS

An in-vitro experimental study was conducted at the Central Sterilization Services Department (Dental Clinic) and the Microbiology lab at our university hospital. A total of 130 bands were included in our study which comprised 10 controls and the rest were equally divided into three groups according to the pre-cleaning methods, i.e. manual scrubbing, enzymatic solution and a combination of both. The orthodontic bands were incubated in the brain heart infusion broth at 37 °C for five days after pre-cleaning and sterilisation in a steam autoclave and were assessed for any bacterial growth. The chi-square test was applied to determine any significant association between the various pre-cleaning methods and the frequency of bands that showed growth. Effect size was calculated using the phi coefficient.

RESULTS

The enzyme method revealed 5% of the sample to exhibit bacterial growth, whereas manual scrubbing and the combination of both showed no growth. There was no statistically significant difference among the three methods (P = 0.131). Further investigations showed the presence of Staphylococcus non-aureus bacterial species in contaminated bands from group II.

CONCLUSIONS

All pre-cleaning methods were found to be equally effective in the decontamination of bands. Hence, the tried-in bands can be safely reused after pre-cleaning and sterilisation.

A comparison of decontamination methods of tried-in preformed metal crowns: an in-vivo study

AIM

To compare the effectiveness of different decontamination methods on tried-in preformed metal crowns (PMCs).

METHODS

Sixty unused PMCs and 90 tried-in PMCs from patients were assessed for contamination after culturing for 24 h on liquid media, solid media and differential media for identification of Streptococcus mutans, Staphylococcus aureus, and Escherichia coli. Subsequently, these PMCs were divided equally into the following six groups: autoclave (121 °C, 15 psi for 15 min), 5% sodium hypochlorite (5 min), 5% glutaraldehyde (5 min), 70% isopropyl alcohol (1 min) and normal saline (5 min). The contamination was reassessed, and the Log₁₀ counts were compared to the pre-decontamination levels using one way ANOVA and paired t-test at a significance level of p < 0.05.

RESULTS

The mean percentage reduction in colony counts was significantly more in the autoclave group compared to glutaraldehyde or sodium hypochlorite groups, glass bead, isopropyl alcohol, and normal saline in this decreasing order.

CONCLUSIONS

PMCs supplied by the manufacturer were found to be sterile and can be used directly on patients. The autoclave was the best method of sterilisation, although it did not eliminate the microbes 100%; followed by 5% glutaraldehyde and 5% sodium hypochlorite.

Pathological evaluation for sterilization of routinely used prosthodontic and endodontic instruments

Background:

In daily practice of dentistry, we use same instruments on many patients. Before use, all instruments must be cleaned, disinfected, and sterilized to prevent any contamination. Pre-cleaning and sterilization of some devices can be difficult because of their small size and complex architecture. Dental burs and endodontic files are such instruments. Dental burs come in a variety of shapes and sizes, all with highly complex and detailed surface features.

Aim:

To determine the effectiveness of various disinfectants and sterilization techniques for disinfection and resterilization of dental burs and endodontic files.

Materials and Methods:

The materials used for the study were dental burs and endodontic files. Disinfectants used were Quitanet plus, glutaraldehyde, glass-bead sterilizer, and autoclave. The sterility of used dental burs and endodontic files was analyzed. Burs and files that had been used were pre-cleaned, resterilized, and then tested for various pathogens. Each item was transferred by sterile technique into Todd-Hewitt broth, incubated at 37°C for 72 h, and observed for bacterial growth.

Results:

The present study shows that the endodontic files and burs sterilized by autoclaving and glutaraldehyde showed complete sterilization. Burs and files immersed in glutaraldehyde (2.4%) for 12 h showed complete sterilization, whereas Quitanet plus solution and glass-bead sterilizer showed incomplete sterilization.

Conclusion:

The present study results indicate that autoclaving and glutaraldehyde (2.4%) showed complete sterilization. Other methods cannot be relied upon for sterilization.

Decontamination of orthodontic bands following size determination and cleaning

OBJECTIVE

To measure the effectiveness of ultrasonic cleaning for decontaminating orthodontic molar bands following size determination using a quantitative antibody capture assay technique.

DESIGN

A prospective, cross-sectional, clinical and laboratory investigation.

SETTING

The Orthodontic Department of the Charles Clifford Dental Hospital and the Microbiology Laboratory of the School of Clinical Dentistry, Sheffield.

PARTICIPANTS

Thirty-two patients about to start orthodontic treatment with fixed orthodontic appliances.

METHODS

Four first molar bands were tried in the mouth and then removed. They were randomly assigned either for no decontamination (control) or to be decontaminated in an ultrasonic cleaning bath for 15 minutes (experimental). The bands were placed in a predetermined volume of phosphate-buffered saline (PBS) and assayed by enzyme-linked immunosorbent assay (ELISA) for albumin, to detect the presence of blood and amylase, to detect the presence of saliva.

RESULTS

Fifty per cent of decontaminated molar bands showed detectable amounts of amylase, albumin or both. The quantity of detectable amylase was significantly reduced on the cleaned compared with uncleaned bands (P = 0.036); however, the reduction in the quantity of albumin was not statistically significant (P = 0.074).

CONCLUSIONS

Ultrasonic cleaning for 15 minutes reduces, but does not always eliminate, salivary proteins (amylase) from tried-in bands. It is less effective at removing serum protein (albumin). There is a need, therefore, to investigate effective means of cleaning organic material from orthodontic bands if they are to be adequately sterilized and reused.

Decontamination methods used for dental burs - a comparative study

AIMS AND OBJECTIVES

Infection control and modes of sterilizations are the key factors to avoid cross transmission of infection in the field of dentistry. Transmission of disease or infection is noted with improper sterilization of reused instruments. Dental burs are the most important tool in any endodontic or conservative procedures of teeth involving tooth contouring, restorative filling procedures and endodontic procedures. Hence, the present study is undertaken to assess the efficacy of different methods of sterilization or decontamination which are routinely used in dental clinics.

MATERIALS AND METHODS

For the present study 96 round diamond burs were selected and divided into 6 groups. These burs were used for the access cavity preparation to get contamination and subjected for bacteriological culture. After getting base line date burs were subjected to manual scrubbing, hot air oven, glass bead sterilizer, ultrasonic cleaner and autoclave to get post decontamination data.

RESULTS

The study revealed that mean colony forming units/ml of Streptococcus mutans decreased maximum for autoclave with 80% reduction, for Lactobacilli 76% reduction and for Candida albicans maximum reduction seen for glass bead sterilizer with 74%.

CONCLUSION

Findings of our study revealed that none of the methods used were found to be absolutely efficacious in the decontamination of dental burs. However, among the experimental groups used in the present study, autoclave was found to be the relatively best method.

Effect of recycling protocol on mechanical strength of used mini-implants

Purpose. This study evaluated the influence of recycling process on the torsional strength of mini-implants. Materials and Methods. Two hundred mini-implants were divided into 4 groups with 50 screws equally distributed in five diameters (1.3 to 1.7 mm): control group (CG): unused mini-implants, G1: mini-implants inserted in pig iliac bone and removed, G2: same protocol of group 1 followed by sonication for cleaning and autoclave sterilization, and G3: same insertion protocol of group 1 followed by sonication for cleaning before and after sandblasting (Al₂O₃-90 µ) and autoclave sterilization. G2 and G3 mini-implants were weighed after recycling process to evaluate weight loss (W). All the screws were broken to determine the fracture torque (FT). The influence of recycling process on FT and W was evaluated by ANOVA, Mann-Whitney, and multiple linear regression analysis. Results. FT was not influenced by recycling protocols even when sandblasting was added. Sandblasting caused weight loss due to abrasive mechanical stripping of screw surface. Screw diameter was the only variable that affected FT. Conclusions. Torsional strengths of screws that underwent the recycling protocols were not changed. Thus, screw diameter choice can be a more critical step to avoid screw fracture than recycling decision.

Decontamination of viable Streptococcus mutans from orthodontic tungsten carbide debonding burs. An in vitro microbiological study

OBJECTIVES

To investigate the effectiveness of currently recommended decontamination procedures on tungsten carbide debonding burs (TCDBs).

DESIGN

In vitro microbiological study.

SETTING

St George's Hospital NHS Trust, UK.

MATERIALS AND METHODS

A total of 240 extracted tooth surfaces were bonded with orthodontic brackets, debonded to leave residual composite and artificially contaminated with Streptococcus mutans.

INTERVENTION

Sterilized TCDBs in a slow handpiece were used to remove this composite before random allocation into one of six different decontamination groups of 40 burs each. These included a control group that was not decontaminated and a further five that underwent different methods of presterilization cleaning within the decontamination process (none, manual, ultrasonic, washer disinfector and enzyme soak) followed by sterilization in a vacuum phase autoclave at 134 degrees C for 3 min.

MAIN OUTCOME MEASURES

The burs were placed in brain heart infusion (BHI) broths, incubated for 48 h. Following this the broths were inspected for turbidity and microbiological analysis was carried out to detect viable bacterial growth. Data were analysed using the Kruskal-Wallis test for single ordered data.

RESULTS

S. mutans was recovered from 39 out of 40 burs in the control group and no burs from the decontamination groups, which was statistically significant (P = 0.001). No differences were found between decontamination groups (P = 0.271). However, skin flora contamination was noted in 17 broths.

CONCLUSIONS

The five methods of decontaminating TCDBs investigated in this study were effective in removing viable S. mutans. Other investigations are required to determine if TCDBs can be successfully cleaned of blood and protein residue prior reuse.

Decontamination in primary care dentistry

Decontamination of reusable dental instruments has been a subject of debate within the dental profes sion since the publication in 2009 of Health Technical Memorandum 01-05: Decontamination in primary care dental practices. This paper provides a brief history of instrument reprocessing in dentistry and reviews the evidence on pre-soaking, cleaning, sterilisation and storage.

The cleaning of photographic retractors; a survey, clinical and laboratory study

OBJECTIVES

To determine the methods currently being used to decontaminate photographic retractors in specialist orthodontic practice and to investigate the effectiveness of the cleaning methods.

DESIGN

The study was carried out in two parts: I - a postal self-report questionnaire, and II - a cross-sectional clinical and laboratory investigation.

SETTING

The Orthodontic Department of the Charles Clifford Dental Hospital.

SUBJECTS AND MATERIALS

I - The questionnaire was sent to 278 specialist UK orthodontists. II - One hundred and twenty pairs of photographic retractors were collected following use. One retractor from each pair was randomly chosen to be the unwashed control and immediately placed in 20 ml of PBS-Tween for elution. The other was subjected to the one of four cleaning procedures: alcohol wipe, handwashing, ultrasonic bath or washer-disinfector, before being placed in PBS-Tween. Aliquots were taken for assay.

MAIN OUTCOME MEASURES

Antibody capture (ELISA) for amylase, to detect the presence of saliva, and for albumin, to detect the presence of serum.

RESULTS

I - The questionnaire response rate was 65% and the majority of respondents (87.2%) were routinely taking clinical photographs. A wide variety of techniques were being used to decontaminate photographic retractors. II - All unwashed controls had detectable levels of amylase and albumin. All the retractors that were cleaned using an alcohol wipe had residual detectable levels of amylase and 80% had detectable levels of albumin. Only one retractor had detectable amylase and one had detectable albumin following cleaning using the washer-disinfector. There was a highly significant statistical difference between the techniques in the proportional reduction in both amylase and albumin detected from the unwashed control and cleaned experimental retractors (p <0.001). The infective risk from inadequate cleaning of photographic retractors is discussed.

CONCLUSIONS

The washer-disinfector is the most effective method of cleaning photographic retractors, but no method was found to be 100% successful at removing amylase and albumin.

Can protein contamination be removed from hand endodontic instruments?

AIM

The aim of this study was to quantify total protein adhering to hand endodontic files and to measure and compare the efficacy of ultrasonic cleaning and washer-disinfectors, with and without presoaking, in protein removal from clinically contaminated endodontic files.

METHOD

Total protein contamination of the endodontic files was quantified using an assay reagent colorimetric method. Twelve general dental practitioners were recruited to collect clinically contaminated files. One hundred and fifty clinically contaminated files were allowed to air-dry in sterile plastic containers and a further 60 files were immersed, working end down, in enzymatic detergent immediately following clinical use. Thirty clinically contaminated files were tested for total protein contamination as a positive control. Sixty files were subjected to ultrasonic cleaning and 30 to processing in each of the washer-disinfectors. The presoaked files were divided into two groups of 30 for processing in the washer-disinfectors. A further group of brand-new, unused files were tested for protein contamination as a negative control.

RESULTS

Protein was present on 29 of the 30 new files tested. The median total mass of protein recovered from clinically contaminated hand endodontic instruments was 2.046 microg. The most effective method of presterilisation cleaning tested was a presoak in Alkazyme followed by processing in the Miele G7881 washer-disinfector.

CONCLUSION

The most effective method of presterilisation cleaning for hand endodontic files is a presoak in Alkazyme, an alkaline enzymatic detergent, followed by processing in a Miele G7881 washer-disinfector. This study provides up-to-date evidence that newer methods of presterilisation cleaning may fail to remove protein from endodontic hand instruments totally. This may have implications for all reusable dental instruments.

An investigation of the decontamination of Siqveland matrix bands

OBJECTIVES

This study investigated blood contamination of artificially and clinically contaminated Siqveland matrix bands and retainers. A modified version of the recognised Kastle-Meyer test for blood was used to compare the efficacy of enzymatic agents, a washer-disinfector and an instrument washer for pre-sterilisation cleaning of Siqveland matrix bands and retainers.

METHODS

Assembled Siqveland matrix bands were contaminated either artificially with horse blood or clinically during dental treatment. Contaminated assembled matrix bands and retainers were subjected to immersion in an enzymatic agent, automated processing in a washer-disinfector or instrument washer, or a combination of pre-soaking and automatic cleaning. Residual blood contamination from each band and retainer was measured and compared to the volume of blood recovered from an unprocessed control group of contaminated assembled matrix bands or retainers.

RESULTS

Residual blood was recovered from every clinically contaminated assembled Siqveland matrix band and retainer. The volume of blood recovered from assembled Siqveland matrix bands ranged from 0.13-7.1 microl and from retainers, following removal of the matrix band, from 0.001-1.523 microl. The most effective method of pre-sterilisation cleaning for artificially contaminated assembled matrix bands was processing in the washer-disinfector. Conversely, the most effective method for cleaning clinically contaminated assembled matrix bands and retainers was pre-soaking in an enzymatic agent followed by a heavy-duty cycle in an instrument washer.

CONCLUSIONS

It is not possible to clean assembled Siqveland matrix bands using any method currently available to dental practitioners. Matrix bands should be discarded after use on one patient. Once the band is removed, all detectable blood can be removed from the retainer by pre-soaking in an enzymatic detergent followed by processing in an instrument washer.