PubMed · 1819110
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1991. [Instrument hygiene--test for knowledge].. https://pubmed.ncbi.nlm.nih.gov/1819110/
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STATEMENT OF PROBLEM: Conventional diamond burs show several limitations such as the heterogeneity of grain shapes, the difficulty of automation during fabrication, the decrease of cutting effectiveness due to repeated sterilization, and short lifetime. An additional shortcoming may be represented by the potential release of Ni+2 ions from the metallic binder into the body fluids. PURPOSE: This study investigated a new diamond rotative instrument made of a continuous diamond film obtained by chemical vapor deposition (CVD). This bur, characterized by a pure diamond cutting surface without metallic binder between crystals, was compared with a conventional diamond bur. MATERIAL AND METHODS: Cutting tests were followed by SEM examination and electron microprobe analysis (EMA) to trace metallic residues both at the surface of the bur and the substrate. RESULTS: EMA demonstrated that the metals Ni, Cr, Si, and Fe were present in the metallic binder matrix of the conventional bur and could be smeared on the surface of the substrate during cutting. SEM showed that significant loss of diamond particles occurred during cutting. On the other hand, no discrete particles sheared off the CVD bur. The smearing of the metallic binder cannot occur using the new bur. CONCLUSION: The new CVD bur not only proves to be more efficient in its cutting ability and longevity, but also excludes the risk of metal contamination. This last aspect concerns both the pollution of the oral environment and the contamination of the ceramic during the laboratory manufacturing of dental restorations.
Hypodermic needles have sharp cutting edges along their bevels. These can be used to enlarge canal openings and to cut around a broken instrument or other object to be removed. Means of attaching the needle to such foreign objects for removal are discussed.
Straightening of curved canals is one of the most common procedural errors in endodontic instrumentation. This problem is commonly encountered when dental students perform molar endodontics. The purpose of this study was to compare the effect of the type of instrument used by these students on the extent of straightening and on the incidence of other endodontic procedural errors. Nickel-titanium 0.02 taper hand files were compared with traditional stainless-steel 0.02 taper K-files. Sixty molar teeth comprised of maxillary and mandibular first and second molars were treated by senior dental students. Instrumentation was with either nickel-titanium hand files or stainless-steel K-files. Preoperative and postoperative radiographs of each tooth were taken using an XCP precision instrument with a customized bite block to ensure accurate reproduction of radiographic angulation. The radiographs were scanned and the images stored as TIFF files. By superimposing tracings from the preoperative over the postoperative radiographs, the degree of deviation of the apical third of the root canal filling from the original canal was measured. The presence of other errors, such as strip perforation and instrument breakage, was established by examining the radiographs. In curved canals instrumented by stainless-steel K-files, the average deviation of the apical third of the canals was 14.44 degrees (+/- 10.33 degrees). The deviation was significantly reduced when nickel-titanium hand files were used to an average of 4.39 degrees (+/- 4.53 degrees). The incidence of other procedural errors was also significantly reduced by the use of nickel-titanium hand files.