Effectiveness of dental office instrument sterilization procedures

Influence of 3D- printing method, resin material, and sterilization on the accuracy of virtually designed surgical implant guides

STATEMENT OF PROBLEM

Three-dimensional printing has introduced new manufacturing methods. However, information on the influence of the specific printing technology, material, sterilization, and the comparison between printing and milling on the accuracy of surgical guides is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of the manufacturing method (printing and milling), printing technology stereolithography (SLA) and digital light processing (DLP), material, and sterilization on the accuracy of digitally designed surgical implant guides.

MATERIAL AND METHODS

Resin patient replicas with a single edentulous space were used to place 132 implants with digitally designed surgical guides. The accuracy of postoperative implant position was analyzed for the manufacturing method (printing and milling), resin materials, and preoperative autoclaving. To determine 3D accuracy, angular displacement, mean horizontal crestal, apical displacement, and the linear vertical displacement at the apex were calculated separately for each group (n=12). In addition, the surgical guides were qualitatively analyzed by using field emission scanning electron micrograph.

RESULTS

The postoperative angular deviation ranged from 0.76 ±0.52 degrees (Rapidshape D20II with NextDent SG) to 2.43 ±0.64 degrees (Form2 with NextDent SG) (P<.001). Linear horizontal displacement at the crest was smallest for Rapidshape D20II with 3Delta Guide (0.27 ±0.08 mm) and highest for Form2 with NextDent SG (0.54 ±0.10 mm) (P<.001). Linear horizontal displacement at the apex ranged from 0.36 ±0.10 mm (SolFlex 350 with V-Print SG) to 0.89 ±0.32 mm (Form2 with NextDent SG) (P<.001). Considering the vertical position displacement was no more than 0.43 ±0.07 mm (Form2 with NextDent SG) short of the apex, none of the implant tips were displaced apically. Preoperative autoclaving differentially impaired the accuracy of surgical guides.

CONCLUSIONS

The specific manufacturing technique, the 3D printing device, the resin material, and the application of preoperative sterilization all affected the accuracy of the postoperative implant position. Irrespective of the manufacturing method, all implants were placed within the commonly accepted safety distance.

Biologic monitoring and causes of failure in cycles of sterilization in dental care offices in Mexico

BACKGROUND

Biologic indicator tests (BIs) are considered the most meaningful way to verify sterilization.

OBJECTIVE

To monitor the cycles of sterilization using BIs in dry heat sterilizers and steam autoclaves and to identify the causes of failures in the cycles of sterilization in dental offices in San Luis Potosí, México.

METHODS

An invitation to participate was sent to 400 dental offices, and 206 practitioners of 200 dental offices were included. A questionnaire was given to each of the participants, asking for the following information: sterilizer type, operational parameters used (eg, temperature, pressure, and length of exposure), frequency of sterilization cycles per day, use of BIs, and maintenance procedures of the sterilizer. Two hundred thirty sterilizers were monitored using BIs. The sterilizers with positive results were monitored a second and third time to identify the cause of the failure.

RESULTS

Twenty-two percent of practitioners (n = 46) used BIs, and 17% (n = 39) of the sterilizers reported positive results (bacterial growth). The detected failures were a mistake in the procedure (eg, temperature, time, or pressure), an absence of supervision of the procedure performed by the assistant, and improper maintenance.

CONCLUSIONS

There are opportunities to increase information on infection control, to improve the adoption of standard quality control methods for sterilization as a routine process, to improve training on proper testing, and standardize processes.

Biologic monitoring of dental office sterilizers in Mexico

BACKGROUND

Biologic indicators (BIs) are the quality control applicable to sterilization cycles, but their use was not previously taught in Mexican dental schools or recommended by professional associations. A Mexican official standard, the Mexican Official Norm, published by health authorities in 1999 makes it compulsory for dentists to biologically verify sterilization cycles. However, only a few dentists comply because the use of BIs is largely unknown and the standard is not being enforced.

OBJECTIVE

To evaluate the incidence of sterilization failures in a convenience sample of dental offices in Mexico.

METHODS

Spore strips were distributed to dentists interested in using this service. The dentists mailed the processed BIs to the laboratory for culture.

RESULTS

In 6 years, 3277 tests were submitted from 82 dental offices. Thirty-four offices (41%) submitted 1 to 12 tests, 22 (27%) sent 14 to 48 tests, 18 (22%) mailed 49 to 96 tests, and 8 (10%) sent >97 tests. The sterilization methods were steam (74.4%), dry heat (20%), and chemical vapor (5.6%). A total of 242 sterilization failures (7.4% of all cycles) were detected. Convection dry heat failed with a greater frequency with chi(2) analysis (chi(2) = 13.71, P =.0175).

CONCLUSIONS

Sterilization failures occurred in instrument loads used in patient treatment. Steam and chemical vapor under pressure failed less often than convection dry heat. When corrective action is taken, routine use of BIs increases patient safety.

Sterilization of reusable implant components: a pilot study

STATEMENT OF PROBLEM

The placement and restoration of dental implants require the use of numerous reusable instruments and components. The adequate sterilization of reusable instruments and components is essential to prevent cross contamination between patients. Sterilization usually is accomplished with single-use sterilization envelopes. A reusable sterilization vehicle would reduce costs as well as the waste generated in patient care.

PURPOSE

This study was designed to determine the efficacy of a 10-cc Pyrex test tube as a sterilization vehicle for reusable dental implant instruments and components.

MATERIAL AND METHODS

In this study, a reusable dental implant component was placed in a Pyrex test tube, along with a biologic test strip. A control biologic test strip was kept for each test tube. The test tube was closed with a cotton roll folded in half and placed in the opening. Twenty test tubes were prepared. five sets of 4 test tubes were placed in an autoclave in different locations with varying orientations. The autoclave completed a standard sterilization cycle.

RESULTS

The biological monitoring service indicated that the biologic test strips in 100% of the test tubes were sterile, whereas the control strips were 100% nonsterile.

CONCLUSION

A Pyrex test tube sealed with a cotton roll can serve as a sterilization vehicle for reusable dental implant instruments and components.

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.

Sterilization of dental instruments and devices: an update

Dental sterilization techniques have become a focus of attention as a result of disclosure of occupational HIV transmission from an infected dentist to a cluster of patients. Although there has never been a confirmed report of a patient acquiring an infectious blood-borne disease from a dental instrument or device, recommendations for universal sterilization of dental handpieces and other devices have recently been implemented. Because of the higher rate of hepatitis B virus transmissability in the dental health care environment, an upgrade in sterilization protocols may be warranted. Stringent sterilization standards are especially necessary in higher-risk institutional dental care settings. However, a high rate of dental sterilization errors has been reported and traced to operator error. Recent institutional dental sterilization policy changes have been developed to reduce the chance of sterilization error, further diminishing the risk of cross contamination.