Biomedical subjects

Vicente Tadeu Lopes Buono

Publications and source records attributed to Vicente Tadeu Lopes Buono.

4 recordsLinked to original sources

PubMed2005

Influence of simulated clinical use on the torsional behavior of nickel-titanium rotary endodontic instruments.

OBJECTIVE: The aim of this study was to assess the influence of cyclic deformation up to one half and three quarters of the fatigue life of NiTi rotary endodontic instruments on their behavior in torsion. STUDY DESIGN: Thirty sets of 0.04 and 0.06 ProFile instruments in sizes #20, #25, and #30 were randomly divided into 3 groups: 1 contained 10 sets of new files, torsion tested to failure, while the other 2 groups, with 10 sets each, were first submitted to fatigue tests of up to one half and three fourths of their fatigue life, respectively, in geometrical conditions similar to those of the clinical practice and then torsion tested for rupture. RESULTS: Statistical analysis of the values obtained for the torque to failure and maximum angular deflection, using the Student t test at the 95% confidence level, showed that the cyclic deformation of instruments of up to one half and three fourths of their fatigue life gives rise to a significant reduction in these parameters. CONCLUSIONS: The simulated clinical use of ProFile instruments for shaping curved canals adversely affects their torsional properties.

Dental Alloys↗

PubMed2005

Decrease in the fatigue resistance of nickel-titanium rotary instruments after clinical use in curved root canals.

OBJECTIVE: The changes in fatigue resistance of nickel-titanium rotary ProFile instruments after clinical use for shaping 10 curved molar root canals were evaluated in this study. STUDY DESIGN: Twenty-five sets of files #20, #25, and #30 and tapers .04 and .06 were divided into 2 groups, one with 10 sets of new files that were tested in a fatigue test bench device as a control. The other, experimental group, with 15 sets of clinically used files, was tested in the same device. The Student t test was employed to compare mean values of the measured parameters. RESULTS: A statistically significant decrease in the number of cycles to failure was determined for the clinically used files, as compared with the new ones. The fracture point was the same for all files tested. CONCLUSIONS: The clinical use of ProFile instruments for shaping curved canals reduces their fatigue resistance.

Compressive Strength↗

PubMed2002

Fatigue resistance of engine-driven rotary nickel-titanium endodontic instruments.

A comparative study of the fatigue resistance of engine-driven nickel-titanium endodontic instruments was performed, aiming to access the influence of the cutting flute design and of the size of the files that reach the working length in curved canal shaping. Geometrical conditions similar to those found in practice were used. Series 29 #5 ProFile, together with #6 and #8 Quantec instruments, were tested in artificial canals with a 45-degree angle of curvature and 5-mm radius of curvature. It was observed that the size of the instrument, which determines the maximum strain amplitude during cyclic deformation, is the most important factor controlling fatigue resistance. The effect of heat sterilization on the fatigue resistance of the instruments was also examined. The results obtained indicate that the application of five sterilization procedures in dry heat increases the average number of cycles to failure of unused instruments by approximately 70%.

Dental Alloys↗

PubMed2002

The influence of occlusal finish line configuration on microleakage of indirect composite inlays.

PURPOSE: The aim of this in vitro study was to evaluate the influence of occlusal finish line configuration on microleakage of indirect composite inlays. MATERIALS AND METHODS: Forty-five recently extracted premolars were randomly assigned into three groups with different types of occlusal finish line preparations: bevel, chamfer, and butt joint. All restorations were made in Artglass (Heraeus Kulzer) and luted according to the manufacturer's recommendations. The teeth were sealed and then thermocycled 500 times between 5 degrees C and 55 degrees C. After that they were immersed in a 2% methylene blue (pH 7.2) solution for 24 hours. Each tooth was bisectioned in the buccal/lingual direction and then examined microscopically at each section to evaluate the microleakage score. The data were analyzed with chi-square and Fisher's Exact tests. RESULTS: There were no significant differences between the buccal margins of maxillary premolars with occlusal bevel or butt joint; the chamfer had the worst performance. In the buccal margin of mandibular premolars, the bevel and chamfer showed significantly smaller amounts of leakage than the butt joint. No significant differences were observed between the three types of occlusal cavosurface preparations in the lingual margin of maxillary and mandibular premolars. CONCLUSIONS: The finish line configuration, the position of the teeth in the arch, and the margin (buccal vs lingual) influenced microleakage. Whenever microleakage was observed in this study, it was always observed at the tooth-cement interface.

Acid Etching, Dental↗