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Journal of the Mechanical Behavior of... May 2024To investigate the influence of the zirconia and sintering parameters on the optical and mechanical properties.
OBJECTIVES
To investigate the influence of the zirconia and sintering parameters on the optical and mechanical properties.
METHODS
Three zirconia materials (3/4Y-TZP, 4Y-TZP, 3Y-TZP) were high-speed (HSS), speed (SS) or conventionally (CS) sintered. Disc-shaped specimens nested in 4 vertical layers of the blank were examined for grain size (GS), crystal phases (c/t'/t/m-phase), translucency (T), and biaxial flexural strength. Fracture load (FL) of three-unit fixed dental prostheses was determined initially and after thermomechanical aging. Fracture types were classified, and data statistically analyzed.
RESULTS
4Y-TZP showed a higher amount of c + t'-phase and lower amount of t-phase, and higher optical and lower mechanical properties than 3Y-TZP. In all materials, T declined from Layer 1 to 4. 3/4Y-TZP showed the highest FL, followed by 3Y-TZP, while 4Y-TZP showed the lowest. In 4Y-TZP, the sintering parameters exercised a direct impact on GS and T, while mechanical properties were largely unaffected. The sintering parameters showed a varying influence on 3Y-TZP. Thermomechanical aging resulted in comparable or higher FL.
CONCLUSION
3/4Y-TZP presenting the highest FL underscores the principle of using strength-gradient multi-layer blanks to profit from high optical properties in the incisal area, while ensuring high mechanical properties in the lower areas subject to tensile forces. With all groups exceeding maximum bite forces, the examined three-unit FDPs showed promising long-term mechanical properties.
PubMed: 38759588
DOI: 10.1016/j.jmbbm.2024.106580 -
Brazilian Oral Research 2024This study assessed the reliability of a color measurement method using images obtained from a charge-coupled device (CCD) camera and a stereoscopic loupe. Disc-shaped...
This study assessed the reliability of a color measurement method using images obtained from a charge-coupled device (CCD) camera and a stereoscopic loupe. Disc-shaped specimens were created using the composite Filtek Z350 XT (shades DA1, DA2, DA3, and DA4) (n = 3). CIELAB color coordinates of the specimens were measured using the spectrophotometer SP60 over white and black backgrounds. Images of the same specimens were taken using a CCD camera attached to a stereoscopic loupe. The color of the image was measured (red-green-blue [RGB]) using an image processing software and converted to CIELAB coordinates. For each color coordinate, data from images were adjusted using linear regressions predicting those values from SP60. The whiteness index for dentistry (WID) and translucency parameter (TP00) of the specimens as well as the color differences (ΔE00) among pairwise shades were calculated. Data were analyzed via repeated-measures analysis of variance and Tukey's post hoc test (α = 0.05). Images obtained using the loupe tended to be darker and redder than the actual color. Data adjustment resulted in similar WID, ΔE00, and TP00 values to those observed for the spectrophotometer. Differences were observed only for the WID of shade DA3 and ΔE00 for comparing DA1 and DA3 over the black background. However, these differences were not clinically relevant. The use of adjusted data from images taken using a stereoscopic loupe is considered a feasible method for color measurement.
Topics: Reproducibility of Results; Composite Resins; Color; Spectrophotometry; Colorimetry; Analysis of Variance; Materials Testing; Reference Values; Linear Models; Image Processing, Computer-Assisted
PubMed: 38747819
DOI: 10.1590/1807-3107bor-2024.vol38.0032 -
Medicine and Pharmacy Reports Apr 2024Dental veneers have become increasingly required among patients, but little is known about the optical properties of veneers obtained from the same ceramic material...
BACKGROUND AND AIMS
Dental veneers have become increasingly required among patients, but little is known about the optical properties of veneers obtained from the same ceramic material through different processing techniques.
METHODS
In this study we compared the translucency and the opalescence parameters of zirconia-reinforced lithium silicate (ZLS) veneers restorations fabricated through CAD/CAM milling and hot-pressing techniques on the upper central incisor. Eighty specimens divided into 8 groups (n=10) were sectioned (Celtra Duo) and heat pressed (Celtra Press) to obtain 0.8 mm thickness. The optical parameters were calculated from the color difference against different backgrounds. Analysis of variance, one way ANOVA and post-hoc multiple comparison tests were used to evaluate and compare the optical properties of the same material, with a significance level of p < 0.05.
RESULTS
The processing method had significant effect on optical parameters. Celtra Duo HT proved to be the material with the highest transparency degree. The hot-pressing technique led to higher opacity than CAD/CAM milling technique.
CONCLUSIONS
For a bio-mimetic aesthetic prosthetic restoration, the ceramic materials must have the same translucency and opacity as the real tooth. The results of this study revealed that high translucency ZLS obtained through hot pressing technique was the material of choice, as it fulfilled these requirements.
PubMed: 38746037
DOI: 10.15386/mpr-2654 -
PloS One 2024Pregnancy increases the risk of periodontitis due to the increase in progesterone and estrogen. Moreover, periodontitis during pregnancy is associated with development...
INTRODUCTION
Pregnancy increases the risk of periodontitis due to the increase in progesterone and estrogen. Moreover, periodontitis during pregnancy is associated with development of pregnancy and birth related complications. The aim of this study is to determine, whether periodontal treatment during pregnancy can reduce systemic inflammation and lower the risk of adverse pregnancy and birth related outcomes.
METHODS AND ANALYSIS
The PROBE study is a non-randomized controlled intervention study conducted among 600 pregnant women with periodontitis. The women will be recruited among all pregnant women at two Danish hospitals in Region Zealand during their nuchal translucency scan and will subsequently be screened for periodontitis. The intervention group includes 300 pregnant women, who will be offered state-of-the-art periodontal treatment during pregnancy. The control group includes additional 300 pregnant women, who will be offered periodontal treatment after giving birth. Outcome measures include periodontal measures, inflammatory, hormonal and glycaemic markers as well as the prevalence of preterm birth risk, low birth weight and risk markers of gestational diabetes mellitus (GDM) and preeclampsia that will be collected from all screened women and further during pregnancy week 20 and pregnancy week 35 for women enrolled in the intervention.
ETHICS AND DISSEMINATION
The study's findings will be published in peer reviewed journals and disseminated at national and international conferences and through social media. The PROBE study is designed to provide important new knowledge as to whether periodontal treatment during pregnancy can reduce the prevalence of complications related to pregnancy and birth.
CLINICAL TRIALS REGISTRATION
The study was registered on clinicaltrials.gov (NCT06110143).
Topics: Adult; Female; Humans; Infant, Newborn; Pregnancy; Diabetes, Gestational; Infant, Low Birth Weight; Periodontitis; Pre-Eclampsia; Pregnancy Complications; Pregnancy Outcome; Premature Birth
PubMed: 38739615
DOI: 10.1371/journal.pone.0302010 -
Heliyon May 2024Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia that presents with abnormalities in the craniofacial region, teeth, and clavicles and is...
INTRODUCTION
Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia that presents with abnormalities in the craniofacial region, teeth, and clavicles and is linked to mutation. Prenatal diagnoses of CCD have rarely been reported, and most of these cases have a positive family history. Here we report two prenatally diagnosed CCD cases without a positive family history. We conducted a literature review to summarize the prenatal sonographic findings of CCD.
CASE REPORTS
Case 1 (a 26-year-old woman): ultrasound at 13 weeks showed a thickened nuchal translucency with absent nasal bones and poor ossifications in the cranium and vertebrae. Genetic testing confirmed a frame shift deletion of . Case 2 (a 27-year-old woman): ultrasound at 32 weeks showed potential fetal skeletal dysplasia, with inadequate skull ossification, mild ossified bilateral clavicles, and frameshift deletion mutation. Both cases were diagnosed with CCD and the parents chose pregnancy termination.
CONCLUSION
These cases underscore the importance of sonographic examination for prenatal CCD diagnosis with a negative family history. By reviewing previous cases, we concluded that combining NB hypoplasia, clavicle and skull hypoplasia, and shortened long bones may be effective for early screening for CCD. Prenatal diagnosis is crucial for guiding medical decisions.
PubMed: 38737280
DOI: 10.1016/j.heliyon.2024.e29816 -
Journal of Prosthodontics : Official... May 2024To evaluate the fracture resistance of zirconia overlays, considering various preparation designs and the presence of endodontic access.
PURPOSE
To evaluate the fracture resistance of zirconia overlays, considering various preparation designs and the presence of endodontic access.
MATERIALS AND METHODS
Ninety translucent zirconia (5Y-PSZ) overlay restorations were divided into six groups (n = 15/group) based on different preparation designs, with and without endodontic access: chamfer margin 4 mm above the gingival level without (group 1) and with endodontic access (group 2); margin 2 mm above the gingival level without (group 3) and with endodontic access (group 4); overlay with no chamfer margin without (group 5) and with endodontic access (group 6). Restorations were bonded to mandibular first molar resin dies, and the groups with endodontic access were sealed with flowable resin composite. All restorations underwent 100,000 cycles of thermal cycling between 5°C and 55°C, followed by loading until fracture. Maximum load and fracture resistance were recorded. ANOVA with Tukey post-hoc tests were used for statistical comparison (α < 0.05).
RESULTS
Fracture resistance significantly varied among overlay designs with and without endodontic access (p < 0.001), except for the no-margin overlays (groups 5 and 6). Overlays with a 2 mm margin above the gingival margin with endodontic access (group 4) exhibited significantly higher fracture resistance compared to both the 4-mm supragingival (group 2) and no-margin (group 6) designs, even when compared to their respective intact groups (groups 1 and 5). There were no significant differences between the no-margin and 4-mm supragingival overlays.
CONCLUSION
The more extensive zirconia overlay for mandibular molars is the first choice since the 2 mm margin above the gingival level design withstood considerable loads even after undergoing endodontic access. A no-margin overlay is preferred over the 4-mm supragingival design as it preserves more tooth structure and there was no outcome difference, irrespective of endodontic access. Caution is warranted in interpreting these findings due to the in vitro nature of the study.
PubMed: 38734932
DOI: 10.1111/jopr.13865 -
Materials (Basel, Switzerland) Apr 2024In the realm of high-tech materials and energy applications, accurately measuring the transient heat flow at media boundaries and the internal thermal conductivity of...
In the realm of high-tech materials and energy applications, accurately measuring the transient heat flow at media boundaries and the internal thermal conductivity of materials in harsh heat exchange environments poses a significant challenge when using conventional direct measurement methods. Consequently, the study of photothermal parameter reconstruction in translucent media, which relies on indirect measurement techniques, has crucial practical value. Current research on reconstructing photothermal properties within participating media typically focuses on single-objective or time-invariant properties. There is a pressing need to develop effective methods for the simultaneous reconstruction of time-varying thermal flow fields and internal thermal conductivity at the boundaries of participating media. This paper introduces a computational model based on the numerical simulation theory of internal heat transfer systems in participating media, stochastic particle swarm optimization algorithms, and Kalman filter technology. The model aims to enable the simultaneous reconstruction of various thermal parameters within the target medium. Our results demonstrate that under varying levels of measurement noise, the inversion results for different target parameters exhibit slight oscillations around the true values, leading to a reduction in reconstruction accuracy. However, overall, the model demonstrates robustness and accuracy in ideal conditions, validating its effectiveness.
PubMed: 38730894
DOI: 10.3390/ma17092088 -
Carbohydrate Polymers Aug 2024The growing concerns on environmental pollution and sustainability have raised the interest on the development of functional biobased materials for different...
The growing concerns on environmental pollution and sustainability have raised the interest on the development of functional biobased materials for different applications, including food packaging, as an alternative to the fossil resources-based counterparts, currently available in the market. In this work, functional wood inspired biopolymeric nanocomposite films were prepared by solvent casting of suspensions containing commercial beechwood xylans, cellulose nanofibers (CNF) and lignosulfonates (magnesium or sodium), in a proportion of 2:5:3 wt%, respectively. All films presented good homogeneity, translucency, and thermal stability up to 153 °C. The incorporation of CNF into the xylan/lignosulfonates matrix provided good mechanical properties to the films (Young's modulus between 1.08 and 3.79 GPa and tensile strength between 12.75 and 14.02 MPa). The presence of lignosulfonates imparted the films with antioxidant capacity (DPPH radical scavenging activity from 71.6 to 82.4 %) and UV barrier properties (transmittance ≤19.1 % (200-400 nm)). Moreover, the films obtained are able to successfully delay the browning of packaged fruit stored over 7 days at 4 °C. Overall, the obtained results show the potential of using low-cost and eco-friendly resources for the development of sustainable active food packaging materials.
Topics: Food Packaging; Lignin; Nanocomposites; Cellulose; Wood; Nanofibers; Xylans; Tensile Strength; Antioxidants; Fruit
PubMed: 38710545
DOI: 10.1016/j.carbpol.2024.122112 -
Contemporary Clinical Dentistry 2024This study assessed light transmission through ceramic discs varying in shade, translucency, and thickness using light-polymerizing units with different radiant...
Light Polymerization through Glass-ceramics: Influence of Light-polymerizing Unit's Emitted Power and Restoration Parameters (Shade, Translucency, and Thickness) on Transmitted Radiant Power.
BACKGROUND
This study assessed light transmission through ceramic discs varying in shade, translucency, and thickness using light-polymerizing units with different radiant power/flux (RP) outputs.
METHODS
Disc-shaped specimens (0.5 mm, 1.0 mm, and 2.0 mm) were made from high and low-translucency glass-ceramic ingots (IPS e.max Press) in shades A1 and A4, totaling 60 discs. Two light-polymerizing units with different power outputs were used, and their emission spectra were verified. The transmitted RP values for each ceramic specimen were measured and irradiance and radiant energy influx were calculated. Differences between the light-polymerizing units and the influence of the three ceramic parameters were evaluated using an independent-samples -test and three-way analysis of variance (ANOVA) tests (α = 0.05).
RESULTS
A statistically significant difference was observed in the mean transmitted RP values between the two light-polymerizing units. Furthermore, the three-way ANOVA test showed a significant effect of shade, translucency, and thickness, as well as a significant interaction between each pair of variables and all three variables on the transmitted RP ( < 0.05).
CONCLUSIONS
Despite the significant attenuation in the transmitted RP, especially in ceramics with higher shade chromaticity and thickness and lower translucency, the calculated minimal irradiance values for both light-polymerizing units (their emitted power ≥ 500 mW) were greater than the minimum recommended irradiance threshold (100 mW/cm). However, the exposure duration needs to be increased to provide the resin with sufficient radiant exposure for adequate polymerization.
PubMed: 38707663
DOI: 10.4103/ccd.ccd_124_23