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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 -
The Journal of the American Academy of... Feb 2015Because of their osteoconductive properties, structural bone allografts retain a theoretic advantage in biologic performance compared with artificial interbody fusion... (Review)
Review
Because of their osteoconductive properties, structural bone allografts retain a theoretic advantage in biologic performance compared with artificial interbody fusion devices and endoprostheses. Present regulations have addressed the risks of disease transmission and tissue contamination, but comparatively few guidelines exist regarding donor eligibility and bone processing issues with a potential effect on the mechanical integrity of structural allograft bone. The lack of guidelines appears to have led to variation among allograft providers in terms of processing and donor screening regarding issues with recognized mechanical effects. Given the relative lack of data on which to base reasonable screening standards, we undertook basic biomechanical evaluation of one source of structural bone allograft, the femoral ring. Of our tested parameters, the minimum and maximum cortical wall thicknesses of femoral ring allograft were most strongly correlated with the axial compressive load to failure of the graft, suggesting that cortical wall thickness may be a useful screening tool for compressive resistance expected from fresh cortical bone allograft. Development of further biomechanical and clinical data to direct standard development appears warranted.
Topics: Allografts; Biomechanical Phenomena; Bone Diseases; Bone Transplantation; Bone and Bones; Humans; Practice Guidelines as Topic
PubMed: 25624364
DOI: 10.5435/JAAOS-D-14-00263 -
Clinical Oral Investigations Aug 2023To evaluate the short-term effects of hard and soft splints of different thicknesses on maximum bite force (MBF) and sleep quality (SQ) in participants with sleep... (Randomized Controlled Trial)
Randomized Controlled Trial
Short-term effect of material type and thickness of occlusal splints on maximum bite force and sleep quality in patients with sleep bruxism: a randomized controlled clinical trial.
OBJECTIVE
To evaluate the short-term effects of hard and soft splints of different thicknesses on maximum bite force (MBF) and sleep quality (SQ) in participants with sleep bruxism (SB).
METHODS
One-hundred-fifteen patients were randomly allocated to five groups: Groups H2(Hard splint-2 mm), H3(Hard splint-3 mm), S2(Soft splint-2 mm), S3(Soft splint-3 mm), and C (control). Outcomes were MBF (assessed with a digital gnathodynamometer) and SQ (assessed with the Pittsburgh Sleep Quality Index). Measurements were performed at T0 (before the splints), T1 (1-month follow-up), and T2 (2-months follow-up). Data were analyzed using one-way analysis of variance(ANOVA), Tukey's HSD, and chi-square tests (alpha = 0.05).
RESULTS
At T1, the highest MBF values were observed in group H3 (658.01 ± 22.6 N), while the lowest in group S2 (585.45 ± 8.68 N). For T2, the highest values were obtained in H3 group (676.85 ± 21.9 N), and the lowest in group S2 (565.65 ± 10.9 N) (p < 0.05).For SQ, groups S2 and S3 revealed the lowest PSQI values at T1 (9.1; 9.6) and T2 (9; 9.5) (p < 0.001).
CONCLUSIONS
The short-term use of both 2 and 3-mm thick soft splints resulted in a decrease in MBF. Improvement in SQ in patients using soft splints was observed in the 1st month and was maintained in the 2nd month.
CLINICAL RELEVANCE
This study provides insights on short-term clinical effects as regards to increased sleep quality and regulated maximum bite force as a function of splint material type and the thickness of the splint.
Topics: Humans; Sleep Bruxism; Occlusal Splints; Bite Force; Sleep Quality; Splints; Bruxism
PubMed: 37127807
DOI: 10.1007/s00784-023-05049-4 -
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 -
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 -
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 -
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 -
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 -
Cornea May 2017To improve the safety, reproducibility, and depth of effect of corneal cross-linking with the ultraviolet A (UV-A) exposure time and fluence customized according to the...
PURPOSE
To improve the safety, reproducibility, and depth of effect of corneal cross-linking with the ultraviolet A (UV-A) exposure time and fluence customized according to the corneal thickness.
METHODS
Twelve human corneas were used for the experimental protocol. They were soaked using a transepithelial (EPI-ON) technique using riboflavin with the permeation enhancer vitamin E-tocopheryl polyethylene glycol succinate. The corneas were then placed on microscope slides and irradiated at 3 mW/cm for 30 minutes. The UV-A output parameters were measured to build a new equation describing the time-dependent loss of endothelial protection induced by riboflavin during cross-linking, as well as a pachymetry-dependent and exposure time-dependent prescription for input UV-A fluence. The proposed equation was used to establish graphs prescribing the maximum UV-A fluence input versus exposure time that always maintains corneal endothelium exposure below toxicity limits.
RESULTS
Analysis modifying the Lambert-Beer law for riboflavin oxidation leads to graphs of the maximum safe level of UV-A radiation fluence versus the time applied and thickness of the treated cornea. These graphs prescribe UV-A fluence levels below 1.8 mW/cm for corneas of thickness 540 μm down to 1.2 mW/cm for corneas of thickness 350 μm. Irradiation times are typically below 15 minutes.
CONCLUSIONS
The experimental and mathematical analyses establish the basis for graphs that prescribe maximum safe fluence and UV-A exposure time for corneas of different thicknesses. Because this clinically tested protocol specifies a corneal surface clear of shielding riboflavin on the corneal surface during UV-A irradiation, it allows for shorter UV-A irradiation time and lower fluence than in the Dresden protocol.
Topics: Collagen; Cornea; Cross-Linking Reagents; Humans; Models, Theoretical; Photochemotherapy; Photosensitizing Agents; Reproducibility of Results; Riboflavin; Ultraviolet Rays
PubMed: 28257382
DOI: 10.1097/ICO.0000000000001160 -
Archives of Gynecology and Obstetrics May 2023To evaluate whether different measurements of endometrial thickness pre-IVF cycle and during the IVF cycles as measured by transvaginal ultrasound are associated with...
PURPOSE
To evaluate whether different measurements of endometrial thickness pre-IVF cycle and during the IVF cycles as measured by transvaginal ultrasound are associated with the absence or presence of endometrial polyps.
DESIGN
A retrospective cohort study was conducted in a university-affiliated fertility center. Patients were women who underwent two embryo transfer cycles and failed to conceive.
INTERVENTIONS
hysteroscopic evaluation and resection of any masses.
RESULTS
There was no difference on comparing the groups with and without polyps in the mean endometrial thicknesses at baseline scans pre-treatment or during IVF cycle. For women who failed two embryo transfer cycles, at any given endometrial thickness the probability of the presence of a polyp was 30-40%. ROC curves failed to detect an actionable relationship with different endometrial thicknesses and the relationship with an endometrial polyp, with most areas under the curve being just above 0.5. However, once the maximum stimulated endometrial thickness was ≥ 13 mm, there was a 70% chance of a polyp being noted at hysteroscopy. This was a statistical difference in the probability of a polyp being present as compared to the lesser thicknesses (p = 0.05).
CONCLUSION
Baseline or maximum stimulated endometrial thickness at IVF fails to predict with accuracy the presence of a polyp. However, if the maximum stimulated thickness was at least 13 mm, there was a higher probability of a uterine polyp being present. Such a cutoff would nevertheless miss most polyps. At any baseline thickness on CD 2-5, a polyp has a 30-40% probability of being present in women who failed two embryo transfers. ROC curves suggest that at baseline, or maximum stimulated endometrial thickness, the ability to predict a polyp is no better than flipping a coin. As such, endometrial cavity evaluation for polyps is legitimate in women with two embryo transfers irrelevant of the baseline or stimulated thickness.
Topics: Pregnancy; Humans; Female; Retrospective Studies; Uterine Neoplasms; Endometrium; Hysteroscopy; Embryo Transfer; Polyps; Fertilization in Vitro
PubMed: 35680687
DOI: 10.1007/s00404-022-06646-6