CRA
Response to JADA Report - Does Chemiclave
Sterilize?
Additional page included with September 1998 Newsletter
| Contents: | 1. | Original Response to JADA Report as appeared in Sept. 1998 CRA Newsletter |
| 2. | Materials & Methods - Sterilization Testing with Handpieces in the Chemiclave | |
| 3. | Results - Sterilization Testing with Handpieces in the Chemiclave |
JADA
Report provokes Chemiclave owners to ask -
Does their chemiclave sterilize handpieces?
CRA repeated experiments reported in JADA. Answer is YES. A 1 million spore challenge is killed by the regular clinical cycle time of 20 minutes even when the spores are dried into the very small lumens of water coolant & chip air lines, as placed by JADA author. -- But NO when sterilization time is reduced to 10 minutes to meet FDA overkill margin of safety.
Explanation of Some Confusing Points -
The report published in JADA (Kolstad, R.A., JADA, 1998; 129:985-991) was a research report, not a clinical report. Testing was conducted following general guidelines used by manufacturers to register sterilizers in the U.S. claiming ability to sterilize handpieces. Currently, acceptable sterilizer margin of safety is established by doubling the time necessary to kill 1 million spores delivered in a challenging manner. Hence, short cycle times, not the 20 minute clinical cycle time were used by the author.
The report does not indicate failure of Chemiclave to sterilize handpieces using the 20 minute cycle time clinicians use, but it does indicate need to review the Chemiclave's margin of safety for handpiece sterilization. This important distinction was not made in the report, & this has been the root of inquiring clinicians' frustration & confusion. Concluding remarks in the JADA report advised clinicians to abandon the Chemiclave & order an autoclave, & use a pressure cooker until the autoclave arrived. This implied strongly that Chemiclaves cannot sterilize handpieces at all. This is not the case. CRA's repeat of Kolstad's work confirmed that 3 different Chemiclaves (EC 5500, EM 5500, 5500) did not kill all the spores at 10 minutes (the half-time needed for margin of safety for a 20 minute full cycle). However, CRA also tested at 15, 18, & 20 minute sterilization times & showed kill of all spores in every run at 18 & 20 minutes. 15 minute times yielded mixed results. This means the Chemiclave can sterilize handpieces inoculated with one million spores when used as it has been clinically for many years, but it does not meet the overkill margin of safety. Sterilization time would need to be extended to about 40 minutes to fulfill this stipulation.
Steam sterilization is no panacea. It has long been known that steam sterilization penetrates better than chemical Vapo-Steril, & this was again demonstrated in Kolsad's report. But 100% humidity of steam causes fiber optic degradation, rusting, & removal of water soluble lubricants. Steam sterilization is not a method that preserves handpiece function best for all handpiece designs (See Apr. `95 CRA Newsletter, graph on p2 on durability of handpieces in different types of sterilizers). Unfortunately, when sterilizing handpieces there are 2 equally important criteria: (A) The handpiece must be sterile & (B) The handpiece must survive the sterilization process in working condition. Kolstad's report does not address the second criterion at all, but clinically it cannot be ignored because a handpiece is a key instrument in patient treatment.
Recommendation to use a pressure cooker to sterilize handpieces is inappropriate because: (A) They are not calibrated for metal instruments & the overload quantity negating sterilization is unknown; (B) They generally do not have gages necessary to check pressure, temperature, & time during operation to prevent dangerous overheating; & (C) They are not considered medical devices & are not FDA cleared for use in healthcare environments for use with handpieces, or any other instruments.
Many sterilizers used in dentistry today for handpieces sterilization may not meet overkill margin of safety test methods Kolstad used. Very few dental clinicians are aware that sterilizer companies claiming handpiece sterilization must submit data to FDA to verify this claim. Unknowingly, clinicians have added handpieces to their regular sterilization loads, & never suspected anything special was needed. Today, most sterilizers used clinically do not have FDA clearance for sterilization of handpieces. Of 10 currently active sterilizer companies contacted by CRA, only 5 had 510 (k) numbers to support this claim, & when clearance was obtained, it applied only to certain models in their lines. Table below lists status of all sterilizers called by CRA. Grayed rows indicate companies & specific sterilizer models that have FDA clearance for handpiece sterilization. Several major companies could not be called because they are out of business, such as Castle, yet their sterilizers are used in many dental offices, but will now never be submitted to FDA for handpiece sterilization verification.
| Sterilizers Currently On Market That Manufacturer Claims Has FDA Clearance For Handpiece Sterilization (chart updated 10/98) | ||||
| Company Contacted By CRA | Sterilizer Model | Sterilizer Type | FDA Cleared For Handpieces | FDA Clearance # For Handpiece Sterilization |
| 1. Alpha Medical | Cox 6000 | Dry Heat | YES | K881371 |
| 2.
Barnstead/ Thermolyne |
SterileMax | Steam Heat | YES | K953938 |
| 3. Dentronix | No FDA HP clearance | Dry Heat | No | No* |
| 4. KaVo | No FDA HP clearance | Steam Heat | No | No* |
| 5. Midmark Corp. | No FDA HP clearance | Steam Heat | No | No* |
| 6. Pelton & Crane ** | Delta 8 | Steam Heat | YES | K945117 |
| Delta 10 | Steam Heat | YES | K945117 | |
| 7. Porter Inst. Co. | SES 2012 | Steam Heat | YES | K924596 |
| 8. SciCan | StatIM 900 | Steam Heat | YES | K944036 |
| StatIM 2000 | Steam Heat | YES | K915054 | |
| StatIM 5000 | Steam Heat | YES | K962179 | |
| 9. Steri-Dent | No FDA HP clearance | Dry Heat | No | No* |
| 10.Tuttnauer | No FDA HP clearance | Steam Heat | No | No* |
* No means handpiece sterilization claims not made or could not be verified by FDA.
** Since publication Pelton & Crane was purchased by DCI & the Delta line of sterilizers has FDA 510 (k) numbers for handpiece sterilization.
Summary: Considering all the convoluted points discussed above, it is justifiable to wait and watch for now as sterilizer companies & FDA sort out the mess. The recommendation to bring a conventional pressure cooker into the clinical environment as a sterilizer is justifiable only under the most extreme conditions when use of calibrated & controlled medical devices is impossible.