PubMed · 15066509
This article reviews the design and clinical use of the ProTaper NT file system.
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Thomas Clauder, Michael A Baumann. 2004. ProTaper NT system.. https://doi.org/10.1016/j.cden.2003.10.006
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OBJECTIVES: Permanent deformation is one of the most common mechanical complications that affect denture clasps. This can lead to loss of retention and stability of the prosthesis. The purpose of this study was to apply and validate a nonlinear finite element model for permanent deformation prediction in cast denture clasps. Such a model can enhance the process of design optimization and contribute to minimizing the possibility of this problem. METHODS: Cast clasps made from Ti-6Al-7Nb, Co-Cr and Type IV gold alloys were loaded in three different directions (outside, inside and outside inclined 30 degrees ), and the resulting permanent deformation values were recorded. Nonlinear finite element analysis simulations based on the maximum distortion energy criterion for yielding, were conducted for clasp models that were reproduced according to the dimensions of each experimental specimen. Linear regression analysis for the results of the experiment and simulation was performed to verify the validity of the mathematical models. RESULTS: Deflections required to produce specific amounts of permanent deformation were in close agreement with those recorded experimentally. The R2 value for all bending tests was 0.985 and the linear regression equation expressed in micrometers was [DeflectionFEA=0.976 (DeflectionReal)+34]. SIGNIFICANCE: Permanent deformation behavior in the cast clasps with a relatively wide range of deflections (0-2 mm) can be predicted using the proposed model, which shall enhance the design optimization process of cast clasps for denture prostheses.
OBJECTIVE: To compare the shaping ability and safety of engine-driven FlexMaster, GT Rotary, ProFile, ProTaper, and RaCe rotary instrumentation and Hedström hand instrumentation in simulated root canals. STUDY DESIGN: One hundred fifty simulated colored root canals with a curvature of 20 degrees and a radius of 10 mm were randomly distributed among 6 groups of 25 specimens each. After preparation to apical size 30 the area of remaining color on the canal wall indicating unprepared areas was measured in mm2 using image analyzer software. RESULTS: Specimens treated with RaCe left least areas of remaining color compared to all other groups (P < .001), followed by ProTaper. Preparation with ProFile left behind the highest amount of unprepared areas. The ProFile group revealed significantly more remaining color than ProTaper, GT Rotary, and FlexMaster (P < .05). Four FlexMaster files separated. CONCLUSION: RaCe rotary files were safe and more effective compared to the other instruments.
This study investigated the influence of cross-section profile on the mechanical behaviors of six commercial nickel-titanium (NiTi) root canal instruments using the finite element method. The nonlinear mechanical characteristics of the NiTi alloy were taken into account. The six root canal instruments studied were ProTaper, Hero642, Mtwo, ProFile, Quantec, and NiTiflex. Mathematical models for these instruments were constructed and their performances were analyzed under equal torque conditions. The ProTaper and Hero642 models achieved the lowest stress levels that made them the most torque-resistant while the NiTiflex model was the poorest. The maximum stress value and the stress distribution in a model were found strongly influenced by the cross-section profile. Factors affecting the stress distribution include the cross-sectional inertia, depth of the flute, area of the inner core, radial land, and peripheral surface ground. As the area of the inner core of the cross-section increased, the model was more torque-resistant.