The aims of this study were to evaluate the performance of autoclaves and the use of biologic indicators for sterilization control, and to look for predictor variables for improperly functioning autoclaves in Danish dental offices. The study population comprised 314 Danish dental offices (participation rate 94%); 177 from the public Child Dental Service (CDS) and 137 from private practice. A minor questionnaire and five biologic indicators (Attest Biological Indicator for Steam Sterilization, 3M) were sent to the participants. CDS offices were found more inclined to use biologic indicators than PP offices (P less than 0.00001). Among CDS autoclaves 2.3% (95% confidence limit: 0.9-5.7%) failed to sterilize compared to 7.3% (95% confidence limit: 4.0-12.9) of the PP autoclaves. This difference is not statistically significant, but the confidence intervals indicate a possible true difference in favor of a better outcome in the CDS offices. Looking at the whole sample no other predictor variable for inadequate sterilization could be determined as differences were statistically insignificant with regard to years of professional experience, age and brand of autoclave, and use of biological control. Recommendations from an official body stating the approved types of sterilization control in dental offices would be of value.