Roundness measurement devices use a probe that converts the displacement into an electrical signal. In addition to the out-of-roundness information, the measurement signal can contain undesirable ...noise due to mechanical, electrical, thermal, and other influences that can lead to an error in the measurement result. Errors in the rotation of the measuring device spindle are often recognised as the most significant cause of deviation of roundness signal. A prevalent technique for evaluating the precision of spindle rotation entails calibration with the precise measuring sphere. The measurement results incorporate not just the form of the rotation error in the spindle but also other sources of error that can be characterized as random noise. A novel approach for eliminating random noise bias, based on the reduction of Fourier terms proposed by Haitjema and Morel, was implemented to enhance the determination of spindle error.
This study sought to evaluate the efficacy of SWEEPS in the removal of epoxy-resin-based and calcium-silicate-containing endodontic sealer combined with single-cone and carrier-based obturation ...techniques through a micro-CT analysis. Seventy-six single-rooted extracted human teeth with single root canal were instrumented with Reciproc instruments. Specimens were randomly divided into four groups (n = 19) according to the root canal filling material and obturation technique: (1) AH Plus sealer + Reciproc gutta-percha, (2) TotalFill BC sealer + TotalFill BC Points, (3) AH Plus sealer + Guttafusion obturator, and (4) MTA Fillapex + Guttafusion obturator. All specimens were re-treated one week later using Reciproc instruments. Following re-treatment, root canals were additionally irrigated using the Auto SWEEPS modality. The differences in the root canal filling remnants were analyzed by micro-CT scanning of each tooth after root canal obturation, after re-treatment, and after additional SWEEPS treatment. Statistical analysis was performed using an analysis of variance (
< 0.05). The additional treatment with SWEEPS significantly reduced the volume of the root canal filling materials in all experimental groups compared to the removal of root canal filling using only reciprocating instruments (
< 0.05). However, the root canal filling was not removed completely from any of the samples. SWEEPS can be used to enhance the removal of both epoxy-resin-based and calcium-silicate-containing sealers, in combination with single-cone and carrier-based obturation techniques.
The objective of this study was to evaluate the efficacy of reciprocating instruments in the removal of bioceramic and epoxy resin-based sealers using micro-CT analysis. Root canals of 40 extracted ...human teeth were instrumented with a size R25 Reciproc instrument. Specimens were randomly divided into two groups (n = 20) according to the root canal filling material. In the first group, root canals were obturated with AH Plus sealer and Reciproc R25 gutta-percha. In the second group, a combination of bioceramic gutta-percha (TotalFill BC) and bioceramic sealer (TotalFill BC) was used. After one week, the retreatment of all specimens was performed using Reciproc instruments. To analyze the differences in the filling remnants, specimens were scanned in a micro-CT device after obturation and after the retreatment procedure. Statistical analysis was performed using the Mann–Whitney U test (p < 0.05). A combination of bioceramic sealer and bioceramic gutta-percha was more effectively removed from canals using a reciprocating instrument, with a filling remnants volume of 4.01 ± 3.13 mm3, in comparison to the combination of epoxy resin-based sealer and gutta-percha (6.96 ± 2.70 mm3) (p < 0.05). A reciprocating instrument was more effective in removing bioceramic sealers than epoxy resin-based sealers, although none of the root canal filling materials were completely removed from the root canals.
The calibration of screw thread gauges is a conventional procedure in calibration laboratories and National Metrology Institutes. Proper measurement and reliable uncertainty analysis of the screw ...thread gauge calibration are complex and demanding tasks.
Different technical documents and international standards in screw metrology define calibration categories, explain measurement plans, measuring elements, nominal diameters and their tolerances, and propose guidelines for the measurement uncertainty estimation. Therefore, the first part of this paper provides a detailed overview of different technical documents and international standards in screw thread metrology.
The second part of this paper aims to draw attention to critical points of the pitch diameter calibration procedure that lead to a significant increase in measurement uncertainty. Most calibration laboratories do not measure the thread angle during the pitch diameter calibration. Therefore, the selection of the measurement wires can contribute greatly to the measurement uncertainty.
Even though the international standards propose the best size wires to avoid this problem, many manufacturers produce measuring wires according to DIN 2269 (Zeiss). In this paper, the authors do simulations of the contribution of measuring wires to the uncertainty in the calibration of the pitch diameter of metric M threads. A simulation is created for each thread gauge according to ISO 1502, and critical threads, in which a significant increase in measurement uncertainty is expected, are highlighted.
The authors propose a simple solution for avoiding this unwanted increase in measurement uncertainty of pitch diameter calibration; the solution involves replacing the DIN 2269 (Zeiss) wires with the best-size wires only for the highlighted critical threads.
Surface texture is of great importance in specifying the function of a surface. The surface finish of products influences the friction performance, wear resistance, bearing, sliding, lubricating ...properties, functionality, etc. Replicas of surface textures are widely used in many industries for evaluating the condition of textures when no measurable surfaces are available for measurements or in the case of non-dismantled objects of immense dimensions. The replication’s reliability and accuracy are significant concerns in actual applications. Although there are several parameters, Ra and Rz are still most often defined in technical product documentation as the indicators of whether a surface texture is within certain tolerance limits. In real production conditions, tactile stylus profilometers are still the most common instruments for measuring surface texture. For all the reasons mentioned above, the accuracy of the Technovit® 3040 replica was analysed. The quality of the Technovit® 3040 replica was researched on 15 samples processed with six conventional machining methods. Average roughness parameters Ra and Rz were measured on original surfaces and then compared to replica surfaces. A qualitative comparison of the profile geometries of original surfaces and their replicas was discussed.
To analyze the effect of various coating formulations on the mechanical and corrosion properties of nickel-titanium (NiTi) orthodontic wires.
Uncoated, rhodium-coated, and nitrified NiTi wires were ...observed with a three-point-bend test, surface roughness (Ra) measurement, scanning electron microscopy, energy dispersive spectroscopy, and electrochemical testing (open circuit potential, electrochemical impedance spectroscopy, and cyclic polarization scan). Differences in the properties of tested wire types were analyzed with analysis of variance and Tukey post hoc test.
Uncoated and nitrified NiTi wires showed similar mechanical and anticorrosive properties, while rhodium-coated NiTi wires showed the highest Ra and significantly higher modulus of elasticity, yield strength, and delivery of forces during loading but not in unloading. Rhodium-coated NiTi wires also had the highest corrosion current density and corrosion potential, lowest impedance modulus, and two time constants on Bode plot, one related to the Rh/Au coating and the other to underlying NiTi.
Working properties of NiTi wires were unaffected by various coatings in unloading. Nitrification improved corrosion resistance. Rhodium coating reduced corrosion resistance and pronounced susceptibility to pitting corrosion in artificial saliva because of galvanic coupling between the noble coating and the base alloy.
From the very start of their use until today, processes in Additive Manufacturing (AM) have found a way to grow from prototype production to individual and small-series production. Improvements in ...machinery, materials and other challenges in AM development have improved product quality, its mechanical properties and dimensional accuracy. Research in the field of dimensional accuracy must be focused on achieving better tolerances. From the beginning of AM, there has been a big issue in assuring dimensional repeatability and reproducibility of a part being printed over the course of several days. In order to examine that, a test plate was designed and built repeatedly with PolyJet technology over the course of several weeks. Measurements of dimensional accuracy and shape deviations of several typical features were carried out using X-ray Computed Tomography. Measurement results were analysed and presented in order to indicate the repeatability and reproducibility of PolyJet AM technology. Results show that PolyJet technology consistently produces parts within ±100 μm, at a 95% confidence interval, under reproducibility conditions of over a 1-month period. Accuracy for measurands (distance) in the x and y axis was significantly better than it was for the z axis which was from 56 to 197 µm, i.e., in the x and y axis, it was from −8 to 76 µm. Shape errors (i.e., cylindricity) were larger than positional or dimensional errors; this can be attributed to relatively large surface roughness and small feature sizes on the test plate that was used.
Laser surface texturing is a technology that enables us to achieve very complex surface geometries. In this study, geometries created on the Ti-6Al-4V surface were in the form of parallel grooves. ...Those geometries were obtained by changing the laser beam speed and the number of passes (one or two). The effects of laser texturing on the roughness and the contact angle of Ti-6Al-4V surfaces on the first day and after 80 days were investigated. The results of this study indicate that the samples treated with two passes of the laser beam and at a lower speed scan show regularities of roughness profile geometry while other laser-treated samples do not. It is shown that the surfaces laser-textured with either one or two passes of the laser beam show no significant changes in the surface wettability after 80 days. The statistical test proves that there is a significant difference (level α = 0.05) between the contact angles on the untreated sample on the first day and after 80 days of treatment.
To examine the effect of two aging protocols on the chemical and phase composition as well as the surface state of monolithic translucent zirconia ceramics.
Translucent zirconia ceramics ...KATANA-Zirconia STML with different surface treatments (no treatment, K1, K2; glazed, G1-G8; polished, P1-P8) underwent testing in order to examine how the two aging protocols (three-hour hydrothermal degradation in an autoclave at 134 °C and 2 bars: G1-G4, P1-P4, and sixteen-hour chemical degradation in four-percent acetic acid at 80 °C (ISO 6872): G5-G8, P5-P8) affect chemical composition, particularly the share of stabilizing yttrium oxide (Energy Dispersive X-Ray Fluorescence - EDXRF), phase composition (X-ray diffraction - XRD) and surface state in terms of roughness and gloss.
Aging protocols did not affect the tested chemical composition stability of specimens and a high share of stabilizing yttrium-oxide (≥10% of total content), which correlates with the absence of monoclinic phase. A decrease in gloss on all specimens is statistically significant. Chemical degradation substantially increased the surface roughness of tested specimens.
Translucent monolithic zirconia demonstrated a stable chemical composition and resistance to tetragonal-to-monoclinic transformation. Surface gloss was significantly reduced, especially in polished specimens. Contrary to glazed specimens, the tested polished specimens manifested an increase in surface roughness. Glazing the surface of translucent monolithic zirconia produces better esthetic, tribological and hygienic effects than polishing.
To analyze the effect of various fluoride formulations in commercially available agents on working properties of various nickel-titanium orthodontic wires.
Uncoated (NiTi), rhodium coated (RhNiTi) ...and nitrified (NNiTi) wires were immersed to dH2O, MiPaste, Elmex and Mirafluor for 1 h. Unloading slope characteristics (average force, bending action of the force and average plateau length) and the percentage of useable constant force during unloading were observed. Surface roughness (Ra) was measured. SEM and EDS were used for observation of the surface.
NiTi had decreased loading and unloading elastic modulus (E) and yield strength (YS) after immersion to MIPaste and Mirafluor. The unloading YS decreased in the RhNiTi by the MIPaste. The loading and unloading YS of the NNiTi increased in Elmex and increased average plateau force. RhNiTi showed higher average plateau length and the percentage of useful constant force during unloading in Mirafluor and the average plateau force lowered after immersion to MIPaste. The unloading slope characteristics for NiTi were affected by all three prophylactic agents, mostly by Mirafluor, and produced significantly lower forces during both loading and unloading, similarly to the NNiTi wires. The RhNiTi had the lowest forces during both loading and unloading in MIPaste. All results were at significance; p<0.05. Difference in Ra was observed for RhNiTi after immersion to the MI Paste (p<0.001; η2=0.761).
The NiTi and NNiTi wires lose less working force when combined with Elmex. The RhNiTi improve their working properties with Mirafluor and deteriorate when combined with MiPaste.
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