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Clinical Oral Investigations Jun 2019Indirect CAD/CAM restorations can be fabricated using both subtractive and additive CAD/CAM technology. This study investigated the fracture load of crowns fabricated...
OBJECTIVES
Indirect CAD/CAM restorations can be fabricated using both subtractive and additive CAD/CAM technology. This study investigated the fracture load of crowns fabricated from three particle-filled composite CAD/CAM materials and one 3D-printed composite material.
MATERIALS AND METHODS
Lava Ultimate, Cerasmart and Brilliant Crios were used as particle-filled composite CAD/CAM material and els-3D Harz as 3D-printed composite material. For each group, crowns with three different material thicknesses (0.5/1.0/1.5 mm) were fabricated. Control group was composed of ceramic-based CAD/CAM materials e.max CAD and Enamic. Totally, n = 180 crowns were fabricated and adhesively seated on SLA fabricated dies. Thermomechanical loading and fracture testing were performed. The data for fracture loading force were statistically analyzed by two-way ANOVA followed with multiple comparisons by post hoc Tukey's test (α = 0.05).
RESULTS
In contrast to ceramics, all particle-filled composite crowns with 0.5-mm thickness survived fatigue testing. Forces varied statistically significantly. Brilliant Crios showed highest maximum loading force with 1580.4 ± 521.0 N (1.5 mm). Two-way ANOVA indicated that both the material and the thickness affected the fracture load (p < 0.05).
CONCLUSIONS
Particle-filled composite resin CAD/CAM materials may have advantageous material characteristics compared to ceramic CAD/CAM materials for minimal restoration thicknesses.
CLINICAL RELEVANCE
Composite-based CAD/CAM materials may offer new possibilities in minimally invasive restorative treatment concepts.
Topics: Ceramics; Composite Resins; Computer-Aided Design; Crowns; Dental Porcelain; Dental Restoration Failure; Materials Testing; Printing, Three-Dimensional; Stress, Mechanical
PubMed: 30368664
DOI: 10.1007/s00784-018-2717-2 -
Materials (Basel, Switzerland) Dec 2022P-type SbTe films with different thicknesses were deposited on polyimide substrates via heat treatment-assisted DC magnetron sputtering. The correlations between the...
P-type SbTe films with different thicknesses were deposited on polyimide substrates via heat treatment-assisted DC magnetron sputtering. The correlations between the thickness variance and the structure, dislocation density, surface morphology, thermoelectric properties and output power are investigated. As a result, it is clear that the film thickness and the heat treatment process during growth are related to the diffusion of deposited atoms on the substrate surface, leading to imperfection defects inside the films. The imperfections inside the films are affected by their properties. This work also presents the thermoelectric efficiency of a planar single leg of the deposited films with various thicknesses. The maximum power factor is 2.73 mW/mK obtained with a film thickness of 9.0 µm and an applied temperature of 100 °C. Planar SbTe produced a maximum output power of 0.032 µW for a temperature difference of 58 K.
PubMed: 36556656
DOI: 10.3390/ma15248850 -
Healthcare (Basel, Switzerland) Jan 2022All abdominal muscles, including the transverse abdominis (TrA), should be modulated to improve core stability. This study aimed to investigate easier and more effective...
All abdominal muscles, including the transverse abdominis (TrA), should be modulated to improve core stability. This study aimed to investigate easier and more effective core exercise methods by comparing thickness changes in the TrA, internal oblique (IO), external oblique (EO), and rectus abdominis (RA) muscles during the abdominal draw-in maneuver (ADIM) and maximum abdominal contraction maneuver (MACM). Thirty healthy subjects who participated in this study underwent ADIM and MACM three times in random order. We measured the abdominal muscle thickness during ADIM and MACM using ultrasonography and compared the changes in the thickness of TrA, IO, EO, and RA muscles using a paired -test. Significant differences were observed in the thicknesses of all the abdominal muscles between the ADIM and MACM groups ( < 0.05). The MACM immediately increased the thickness of the TrA ( < 0.001, effect size (ES) = 0.931), IO ( = 0.001, ES = 0.761), EO ( = 0.008, ES = 0.415), and RA ( < 0.001, ES = 0.767) muscles. These results suggest that MACM is useful for immediately increasing the thickness of TrA, IO, EO, and RA muscles and may contribute to the clinical effect of simultaneous contractions on the changes in abdominal muscle thickness.
PubMed: 35206865
DOI: 10.3390/healthcare10020251 -
Evidence-based Complementary and... 2022Warm-needle acupuncture (WA) and fire-needle acupuncture are treatment techniques that use the combination of acupuncture and thermal stimulation. In clinical practice,...
BACKGROUND
Warm-needle acupuncture (WA) and fire-needle acupuncture are treatment techniques that use the combination of acupuncture and thermal stimulation. In clinical practice, a new method of fire-needle acupuncture called "heated-needle acupuncture (HA)" has been proposed, wherein the needle is directly heated after insertion. WA and HA share similarities in their methods, and no previous study has sought to assess whether their thermal outcomes are also similar.
METHODS
We controlled environmental variables and measured the maximum temperatures and temperature changes of a silicon phantom in which K-type thermocouples were embedded at depths of 0, 2, 5, 7, and 10 mm. WA and HA were also performed with acupuncture needles of various thicknesses (0.30 × 40 mm, 0.40 × 40 mm, and 0.50 × 40 mm).
RESULTS
Different time-dependent temperature distributions were observed between the two acupuncture methods: HA yielded a higher maximum temperature and temperature change on the surface, whereas WA yielded higher temperatures at the other tested depths. The thermal patterns were similar among the needles of different thicknesses for each method, with the following exception: while the temperature change and maximum temperature did not differ significantly by needle thickness for WA, these parameters increased significantly with needle thickness for HA.
CONCLUSION
The two acupuncture procedures yielded different thermal patterns in a controlled environment. Further studies are necessary to reflect the effect of external environment variables occurring in reality.
PubMed: 35265145
DOI: 10.1155/2022/4159172 -
Frontiers in Bioengineering and... 2021Orthokeratology has been widely used to control myopia, but the mechanism is still unknown. To further investigate the underlying mechanism of corneal reshaping using...
Orthokeratology has been widely used to control myopia, but the mechanism is still unknown. To further investigate the underlying mechanism of corneal reshaping using orthokeratology lenses the finite element method, numerical models with different corneal curvatures, corneal thicknesses, and myopia reduction degrees had been developed and validated to simulate the corneal response and quantify the changes in maximum stress in the central and peripheral corneal areas during orthokeratology. The influence of the factors on corneal response had been analyzed by using median quantile regression. A partial eta squared value in analysis of variance models was established to compare the effect size of these factors. The results showed central and peripheral corneal stress responses changed significantly with increased myopia reduction, corneal curvature, and corneal thickness. The target myopia reduction had the greatest effect on the central corneal stress value (partial eta square = 0.9382), followed by corneal curvature (partial eta square = 0.5650) and corneal thickness (partial eta square = 0.1975). The corneal curvature had the greatest effect on the peripheral corneal stress value (partial eta square = 0.5220), followed by myopia reduction (partial eta square = 0.2375) and corneal thickness (partial eta square = 0.1972). In summary, the biomechanical response of the cornea varies significantly with the change in corneal conditions and lens designs. Therefore, the orthokeratology lens design and the lens fitting process should be taken into consideration in clinical practice, especially for patients with high myopia and steep corneas.
PubMed: 34708026
DOI: 10.3389/fbioe.2021.743745 -
Journal of Physical Therapy Science Oct 2020[Purpose] One-repetition maximum is an essential statistic for physical therapists and coaches in rehabilitation and athletic settings. In a previous study, we showed... (Review)
Review
[Purpose] One-repetition maximum is an essential statistic for physical therapists and coaches in rehabilitation and athletic settings. In a previous study, we showed that one-repetition maximum of the knee extensor could be predicted more accurately with the combination of maximal voluntary isometric contraction strength, as measured by a handheld dynamometer, muscle thickness, and thigh circumference, in young adults. However, there has been no study in older adults investigating the relationship between one-repetition maximum and maximal voluntary isometric contraction strength, or muscle thickness, and thigh circumference. Therefore, the aim of this study was to investigate the relationship between one-repetition maximum and maximal voluntary isometric contraction strength, or muscle thickness, and thigh circumference in older adults. [Participants and Methods] Twenty-eight older community-dwelling adults (18 males and 10 females) participated in this study. Muscle strength of the knee extensor was measured using one-repetition maximum and maximal voluntary isometric contraction strength. In addition, muscle thicknesses of the refutes femoris and the vastus intermedius, and thigh circumference were measured using ultrasonography and measuring tape, respectively. [Results] Stepwise regression analysis revealed that body mass, gender, thigh circumference at 15 cm above the patella, and maximal voluntary isometric contraction strength were significant and independent determinants (R=0.868). [Conclusion] One-repetition maximum could be predicted more accurately using a combination of maximal voluntary isometric contraction strength, as measured with a handheld dynamometer, and thigh circumference in older adults.
PubMed: 33132528
DOI: 10.1589/jpts.32.669 -
Eye (London, England) May 2020To characterize and evaluate the use of corneal epithelial profile maps generated by an ultrahigh-resolution optical coherence tomography (UHR-OCT) in the diagnosis and...
BACKGROUND/OBJECTIVES
To characterize and evaluate the use of corneal epithelial profile maps generated by an ultrahigh-resolution optical coherence tomography (UHR-OCT) in the diagnosis and management of dry-eye disease (DED).
SUBJECTS/METHODS
This prospective, interventional case-control study included 115 eyes of 71 subjects (52 DED and 19 controls) imaged using an UHR-OCT. Average, maximum, and minimum, range of corneal epithelial thicknesses were extracted from epithelial profile maps. Surface regularity was quantified using the range and variance of the epithelial thickness measured along a horizontal UHR-OCT scan. The variance of thickness measurements along a scan was named epithelial irregularity factor (EIF). Symptoms of 31 DED patients (55 eyes) were quantified by questionnaire and correlated to epithelial profile findings, fluorescein staining, tear breakup time, and Schirmer's test. Twenty-one DED eyes were administered autologous serum drops and follow-up UHR-OCT images were captured.
RESULTS
DED patients had a highly irregular corneal epithelial surface compared with controls. Epithelial thickness profile variance (EIF) and range were significantly higher in DED as compared with controls (5.79 vs. 0.77, p < 0.001 and 7.6 vs. 4.6 μm, p < 0.001). Both parameters were highly significantly correlated with questionnaire scores (EIF: r = 0.778; p < 0.001, range: r = 0.737; p < 0.001). Follow-up showed a statistically significant reduction in epithelial thickness profile variance and range of treated patients ( p < 0.001).
CONCLUSIONS
DED patients have irregular epithelial surface that can be quantified using UHR-OCT generated CEP maps. Epithelial thickness profile range and EIF correlate accurately with patients' symptoms and could be used to follow-up patients and response to treatment.
Topics: Case-Control Studies; Cornea; Dry Eye Syndromes; Humans; Prospective Studies; Tears; Tomography, Optical Coherence
PubMed: 31576026
DOI: 10.1038/s41433-019-0592-y -
Journal of Orthodontic Science 2022MH cortical screws were designed to combine the advantages of thick mini-implants with the versatility of micro-screws while avoiding the disadvantages of both.
OBJECTIVE
MH cortical screws were designed to combine the advantages of thick mini-implants with the versatility of micro-screws while avoiding the disadvantages of both.
MATERIALS AND METHODS
An MH cortical screw (MH is an abbreviation for the author's name) was made from titanium material. The screw has a 3 mm-long amphora-shaped shank of 2 mm thickness at its thinnest and 3 mm at its thickest part. Uniform 4 mm diameter threads blend into a 1 mm cutting tip. An external hexagonal head with side retentive ligature holes and a central hole for attachments was fabricated on a saucer-shaped gingival collar. Multiple attachments have been prepared for amending to the central hole.
RESULTS
The shank design allowed cortical plate retention. The uniform threads and the amphora design provided maximum primary and secondary stability, respectively. The self-drilling tip allowed for a flapless technique, while the hexagonal head with side holes facilitated screwdriver control and allows for ligature wire anchorage. Cleats and buttons facilitated the use of elastics and springs, together with bracket-heads and eyelets for titanium molybdenum alloy and nickel-titanium wires inclusion. Adjustable hooks and chains provided versatility of line of action. Cover screws to retain extra-tissue mini-plates applied skeletal anchorage and long-term retention with flapless manipulations.
CONCLUSION
MH cortical screws are a novel and important introduction to orthodontic anchorage. They combine primary and secondary stability with avoidance of root damage together with insertions into attached gingiva only. Multiple and versatile attachments allow for the application of biomechanical techniques according to the clinician's preferences. Extra-tissue mini-plates facilitate maximum anchorage for skeletal control and long-term retention without surgery.
PubMed: 36411811
DOI: 10.4103/jos.jos_49_22 -
Materials (Basel, Switzerland) Aug 2023In this study, CoFeBDy thin films were deposited using a direct current (DC) magnetron sputtering technique. The films were deposited on glass substrates with...
In this study, CoFeBDy thin films were deposited using a direct current (DC) magnetron sputtering technique. The films were deposited on glass substrates with thicknesses of 10, 20, 30, 40, and 50 nm, and heat-treated in a vacuum annealing furnace at 100, 200, and 300 °C. Various instruments were used to examine and analyze the effects of roughness on the magnetic, adhesive, and mechanical properties. From the low frequency alternating current magnetic susceptibility (χ) results, the optimum resonance frequency is 50 Hz, and the maximum χ value tends to increase with the increase in the thicknesses and annealing temperatures. The maximum χ value is 0.18 at a film thickness of 50 nm and an annealing temperature of 300 °C. From the four-point probe, it is found that the resistivity and sheet resistance values decrease with the increase in film deposition thicknesses and higher annealing temperatures. From the magnetic force microscopy (MFM), the stripe-like magnetic domain distribution is more obvious with the increase in annealing temperature. According to the contact angle data, at the same annealing temperature, the contact angle decreases as the thickness increases due to changes in surface morphology. The maximal surface energy value at 300 °C is 34.71 mJ/mm. The transmittance decreases with increasing film thickness, while the absorption intensity is inversely proportional to the transmittance, implying that the thickness effect suppresses the photon signal. Smoother roughness has less domain pinning, more carrier conductivity, and less light scattering, resulting in superior magnetic, electrical, adhesive, and optical performance.
PubMed: 37687687
DOI: 10.3390/ma16175995 -
Journal of the Mechanical Behavior of... Jan 2022In order to determine a suitable thickness of polyetheretherketone (PEEK) for manufacturing of surgical membranes, the purpose was to evaluate how different thicknesses...
In order to determine a suitable thickness of polyetheretherketone (PEEK) for manufacturing of surgical membranes, the purpose was to evaluate how different thicknesses of PEEK influence the mechanical properties under flexure and tension. In total 20 specimens in PEEK with two different thicknesses, 0.5 mm and 1.0 mm were fabricated and tested in a three-point flexural strength test and tensile strength test (n = 5 specimens). Statistical analysis was done with non-parametric Mann-Whitney test with level of significance α = 0.05, for both material tests, respectively. The 1.0 mm-thick samples resulted in higher values in elastic limit and conventional deflection (S-value) in the flexural strength test compared to 0.5 mm-thick samples. In the tensile strength test, the results did not show any significant difference in elastic limit depending on the thickness evaluated. However, PEEK with thickness of 1.0 mm received significantly higher maximum value at fracture. Within the limitations of this study, PEEK with a thickness of 0.5 mm-1.0 mm shows mechanical properties that are appropriate thickness and can meet the complex demands for dimensioning of surgical membranes.
Topics: Benzophenones; Biocompatible Materials; Polymers
PubMed: 34736026
DOI: 10.1016/j.jmbbm.2021.104928