Untersuchung des Kontaminationsgrades von Wurzelkanalinstrumenten aus Zahnarztpraxen

An investigation of the contamination levels of endodontic instruments in dental surgeries The risk of transmission of the Creutzfeldt-Jakob disease by insufficiently cleaned endodontic instruments, previously used to remove potentially infectious nerval tissue, is now being discussed increasingly. The aim of this study is to investigate whether residue of proteins and bacteria are present on used and reprocessed endodontic instruments. Questionnaires provided information on reprocessing and storage methods in dental offices. 300 endodontic hand instruments (10 each from 30 practices in three cities, each in Lower Saxony and Hessen) were tested in this study. 5 of the 10 instruments from one practice were randomly distributed between two testgroups. 30 control instruments were added to each group. For the detection of protein residue the files of the first group were assorted to one Eppendorfcup each, containing 1000µl of distilled water. To dissolve potentially existing proteins from the files, all probes were activated ultrasonically. In order to detect small amounts of protein, all samples were subsequently evaporated in a vacuum device, then diluted to 120µl and mixed with 30µl BioRad assay dye reagent concentrate. 80µl of each sample were measured using a photometer at a wave length of 600nm. The exact quantitative amount of protein was calculated using a standard curve. The remaining 180 instruments of the second group were examined for bacterial growth using the Brain Heart Infusion broth. For this purpose all files were incubated in test tubes with 5ml of the medium for 24 hours at 37oC under aerobic conditions in a water bath. The samples were then evaluated photometrically at a wave length of 600nm. The statistical data was analysed using the program SPSS18.0. 62.7% of the files showed residue of proteins (minimum: 0.12µg; maximum: 14.40µg). Bacterial growth was detected on 22.7% (34 of 150) of the tested instruments. Comparing Lower Saxony and Hessen there appeared to be no significant differences (protein: p = 0.167, bacteria: p = 0.324). The cities showed a tendency towards differences in proteins (p = 0.092) and in bacteria significant differences (p = 0.024). Especially the great range of values of the 75. percentile stood out, extending from 0.00350 to 1.36550. The practices showed, as expected, great differences in protein and bacteria levels. Considering the low number of cases, a reliable statement on the statistical significance of the differences between practices can not be made. The evaluation of the questionnaires showed inconsistent results regarding the methods of reprocessing and storage. The presence of bacterial and protein residue on endodontic instruments raises questions about the risk of transmission of diseases, in particular of the Creutzfeldt-Jakob disease. The non significant differences between the two states can be explaned by the fact that there probably is a steady distribution of “hygiene-aware“ and “hygiene-unaware“ practices and therefore a variety of greatly contaminated or not contaminated instruments. Sterilization is proven to be effective against bacterial residue, which – according to the results of this study - leads to the assumption that there are shortcomings in the storage process in dental practices. However, according to the Robert Koch-Institut the infectious agent of the Creutzfeldt-Jakob disease cannot be inactivated completely by autoclaving at 134oC for 18 minutes. Nevertheless, autoclaving remains standard practice and part of the recommended decontamination process of endodontic instruments. The problem of decontamination methods is reflected in the large number of nonuniform policies and unclear information, but also in the inadequate execution. As long as there is no scientifically proven and practically tested decontamination method known for endodontic instruments, single use of these instruments should be recommended. This, however, will create additional costs as well as environmental concerns.