PubMed · 8409020
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S I Schwarz. 1993. Sterilize it!. https://doi.org/10.14219/jada.archive.1993.0173
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The purpose of this study was to compare canal transportation in moderately curved canals using mechanical instrumentation systems. Mesial roots of mandibular first or second molars were mounted in resin using a modified Bramante muffle system and divided into four groups. The roots were cross-sectioned 2 mm from the working length and at the height of root curvature. Tracings of the canal were made from preinstrumentation slides of the cross-sections. The canals were prepared using ProFile Series 29 rotary instruments, Quantec 2000 rotary instruments, Flex-R files in the Endo Gripper contra-angle handpiece, and Shaping Hedstrom files in the M4 contra-angle handpiece. Tracings of the prepared canals were made onto the originals from postinstrumentation slides. A canal centering ratio was calculated along the line of maximum transportation. Quantec 2000 rotary instruments yielded significantly greater transportation at the apical level when compared with the Profile Series 29 system. There were no other significant differences in transportation at either level. There were no differences in the direction of canal transportation between instrument systems, and the direction of canal transportation was not related to the direction of canal curvature. Canal preparation time was shortest with Profile Series 29 system followed by Flex-R files in the Endo Gripper, Quantec 2000, and Shaping Hedstrom files in the M4.
OBJECTIVE: It has been demonstrated that contamination of the insides of high-speed dental turbines occurs and that bacteria as well as viruses may remain infectious when expelled from such turbines during subsequent use. Consequently, it has been widely recommended that a high-speed turbine be sterilized after each patient. The purpose of this study was to evaluate the effect of steam autoclaving on a high-speed dental turbine with a contaminated turbine chamber. STUDY DESIGN: Streptococcus salivarius and endospores of Bacillus stearothermophilus were used as test organisms to determine the effectiveness of 4 different small non-vacuum autoclaves and one vacuum autoclave. RESULTS: The study demonstrated different efficiencies among the small non-vacuum autoclaves, the best showing close to a 6 log reduction of the test organisms inside the turbine chamber. When cleaning and lubrication of the high-speed dental turbine was carried out before autoclaving, this level of reduction was observed for all the examined non-vacuum autoclaves. CONCLUSIONS: It is concluded that cleaning before sterilization is essential for safe use of high-speed dental turbines and that small non-vacuum autoclaves should be carefully evaluated before being used for the reprocessing of hollow instruments such as high-speed turbines.
AIM: The aim of this study was to determine the shaping ability of ProFile .04 and .06 taper rotary nickel-titanium instruments in simulated canals. METHODOLOGY: A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared using the 'crowndown' approach recommended by the manufacturer. Pre-operative pictures of each canal were recorded on optical discs using an image analysis package. The simulated canals were prepared and postoperative pictures superimposed on the original images. RESULTS: No instrument fractures occurred and none deformed; none of the canals became blocked with debris. Change in working distance was, on average, 0.063 mm with 33 canals retaining the correct length. Overall, five zips (12.5%) were created and 24 (60%) canals demonstrated a widened area on the outer aspect of the canal between the end-point and the curve. Two danger zones (5%) were created and two perforations but no ledges were found. Between canal shapes there were highly significant differences (P < 0.0001) for the incidence of zips and elbows but not for the other aberrations. There were highly significant differences (P < 0.0001) for the total width of the canals between the various canal shapes at the apex of the curve, the beginning of the curve and half way to the orifice, and a significant difference (P < 0.05) at the end-point. There were highly significant differences (P < 0.0001) for the amount of resin removed from the outer aspect of the curve at the end-point and at the beginning of the curve, and significant differences (P < 0.05) at the apex of the curve and half way to the orifice. There were highly significant differences (P < 0.0001) for the amount of resin removed from the inner aspect of the curve at the beginning of the curve and half way to the orifice. Overall, transportation was towards the outer aspect of the canal except at the beginning of the curve. CONCLUSIONS: Under the conditions of this study the combined use of .04 and .06 taper ProFile instruments was rapid, effective and produced good canal shapes except in those specimens with short curves that began near the end-point.