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 bei ng killed during sterilization. The aims of the study were to biologically monitor Norwegian dental office sterilizers and to identify factors contrib uting to sterilization failure. In 1985, participants received a packet con taining: (i) 4 BI units; (ii) a set of instructions; (iii) a questionnaire concerning operation (including biological monitoring) of the office steril izer(s), and (iv) a return-address envelope. In 1996, offices were sent (i) a survey which included demographic questions and inquiries concerning ins trument sterilization processes; (ii) 2 sets of 3 BI units with instruction s for their use on 2 different days; (iii) 1 control BI unit that was not t o 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% overa ll 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 (ch i(2), P < 0.01). Demographic or hygiene procedural factors could not be cor related to sterilization performance (chi(2), P > 0.05). The failure rate f or 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 relate d to issuance in 1986 of Norway's Ist infection control guidelines for dent istry and greater awareness of infection control practices and/or to increa ses over the previous 10 years in the number of postgraduate courses offere d in infection control. The current Norwegian guidelines on infection contr ol practices in public health services, including dentistry, recommend regu lar biological monitoring of sterilizers without specifying how often. Ther e is a lack of information among Norwegian dentists as to how frequently de ntal office sterilizers should be regularly monitored by BI.