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OBJECTIVES: To evaluate and compare the optical properties and relative translucency parameter of CAD-CAM restorative materials. METHODS: Four CAD-CAM materials were evaluated: Lava Ultimate (LU), Grandio Blocs (GB), VITA Enamic (VE), and VITA Mark II (VM). Disk-shaped samples in shade A2-HT were prepared (n = 10) and polished to 1.00 ± 0.01 mm of thickness. Scattering (S), absorption (K), albedo (a) coefficient, transmittance (T%), light reflectivity (RI), infinite optical thickness (X∞), and radiative transfer coefficients (µa, and µ'S) were calculated using Kubelka-Munk method and Thennadil's semi-empirical approach. Root Mean Square Error (RMSE) and Goodness of Fit (GFC) were used as performance optical behavior. Translucency differences were evaluated using the relative translucency parameter (RTP00) and 50:50 % translucency perceptibility and acceptability thresholds (TPT00 and TAT00). RESULTS: The spectral distribution of S, K, T%, RI, and X∞ was wavelength-dependent. GFC and RMSE values indicated good spectral behavior matches and good comparative spectral values for RI in LU-GB, LU-VE, and GB-VE, and for K in VE-VM. VM displayed the highest scattering values across the wavelengths, while VE and VM showed lower absorption at shorter wavelengths. LU and GB had the highest transmittance. The X∞ values indicated that all 1.0 mm thick materials could be influenced by the background. No good spectral match and no good comparative spectral values were found between CAD-CAM materials and anterior bovine maxillary specimens. VM had the lowest RTP00 values with perceptible and unacceptable differences compared to CAD-CAM materials evaluated. SIGNIFICANCE: Understanding the optical behavior of different CAD-CAM materials was essential for guiding clinicians in material selection and optimizing their clinical performance. The findings confirm that the different compositions and microstructure impact the optical properties and translucency of CAD-CAM restorative materials.

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OBJECTIVES: To evaluate the influence of microstructure and chemical composition on the optical properties of CAD-CAM lithium disilicate glass-ceramics. METHODS: Samples (n = 5; 1.0 mm thickness) of shades A1, A2, and A3 were fabricated from CAD-CAM ceramic blocks (Ivoclar Vivadent): IPS e.max® CAD LT (emLT) and HT (emHT). Samples were polished to 1.0 ± 0.01 mm in thickness. The optical properties (R- reflectance; T- transmittance; µs'- reduced scattering and µa- absorption coefficients) from the post-crystallized samples were determined using the inverse adding-doubling (IAD) method based on integrating-sphere measurements. Additionally, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used to evaluate the microstructural properties. Energy-dispersive X-ray (EDX) was employed to analyze the chemical composition. The chemical and structural characterization were performed before and after crystallization of the ceramic samples. RESULTS: emLT showed higher values of µs'and lower values of µa and T than emHT for each shade in all wavelengths (p < 0.003). Considering T for emHT, there were no statistical differences for shades A1 and A2 at 488 nm and 514.5 nm (p > 0.003) and shades A1 and A3 at 457.9 nm (p > 0.003). emLT showed particle length ranging from 0.74 to 2.78 µm (mean = 1.57 µm and RF-relative frequency = 28 %) and particle width ranging from 0.21 to 0.74 µm (mean = 0.30 µm and RF = 31 %). emHT showed particle length ranging from 0.83 to 3.08 µm (mean = 1.86 µm and RF = 21 %) and particle width ranging from 0.24 to 1.12 µm (mean = 0.56 µm and RF = 28 %). In comparison with emHT, emLT showed greater vol% for C, K, and Zr and lower vol% for O and Al. SIGNIFICANCE: The optical properties of CAD-CAM lithium disilicate glass-ceramics are influenced by the chemical composition and, consequently, by the material microstructure.

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STATEMENT OF PROBLEM: In-office bleaching has been widely researched. However, few studies have evaluated alternative protocols for this procedure. Moreover, information on the long-term stability of in-office whitening is limited. PURPOSE: The purpose of this in vitro study was to evaluate the effectiveness and 1-year stability of in-office bleaching with 35% hydrogen peroxide (35%HP) and 37% carbamide peroxide (37%CP) using traditional and alternative protocols. MATERIAL AND METHODS: Forty human third molars were stained with tea and allocated to groups (n=10). Traditional protocols consisted of 3 applications of 35%HP for 15 minutes and 1 application of 37%CP for 45 minutes. Alternative protocols consisted of 1 application of 35%HP for 45 minutes and 3 applications of 37%CP for 45 minutes. Protocols were applied for 3 weeks. CIELab color coordinates were measured at baseline and weekly during treatment and at 1-week, 6-month, and 1-year follow-ups. Effectiveness and stability of the bleaching treatments were interpreted using 50:50% perceptibility and acceptability thresholds. CIELab, chroma, hue angle, and whiteness index were analyzed using the Wilcoxon signed-rank test (α=.05). RESULTS: All protocols showed improvement in bleaching after the first week (P≤.005). All bleaching procedures presented excellent whitening outcomes. Alternative protocols showed a larger rebound effect after 1 year, indicating less stability. For the whiteness index, no differences between the completion of the treatments and 1-year follow-up was found for the bleaching treatments and protocols (P>.05), except for the 37%CP alternative protocol (P=.005). CONCLUSIONS: All tested protocols presented excellent effectiveness in bleaching. Traditional protocols exhibited a greater whiteness stability, while the alternative protocols showed a greater rebound effect after 1 year.

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Biopolymers are biodegradable and renewable and can significantly reduce environmental impacts. For this reason, biocomposites based on a plasticized starch and cross-linker matrix and with a microfibrillated OCC cardboard cellulose reinforcement were developed. Biocomposites were prepared by suspension casting with varied amounts of microfibrillated cellulose: 0, 4, 8, and 12 wt%. Polyethylene glycol diglycidyl ether (PEGDE) was used as a cross-linking, water-soluble, and non-toxic agent. Microfibrillated cellulose (MFC) from OCC cardboard showed appropriate properties and potential for good performance as a reinforcement. In general, microfiber incorporation and matrix cross-linking increased crystallization, reduced water adsorption, and improved the physical and tensile properties of the plasticized starch. Biocomposites cross-linked with PEGDE and reinforced with 12 wt% MFC showed the best properties. The chemical and structural changes induced by the cross-linking of starch chains and MFC reinforcement were confirmed by FTIR, NMR, and XRD. Biodegradation higher than 80% was achieved for most biocomposites in 15 days of laboratory compost.

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OBJECTIVE: To evaluate the optical properties and the relative translucency parameter of Ceramill ZI White (3Y-TZP) and Ceramill Zolid FX White (5Y-PSZ) zirconia ceramic systems and compare them with those of the bovine dentin and enamel/dentin structures. MATERIALS AND METHODS: 3Y-TZP and 5Y-PSZ zirconia ceramic systems were evaluated. A 0.5-mm-thick 3Y-TZP (3Y-NC.5), 0.5-mm-thick (5Y-NC.5), and 1.4-mm-thick (5Y-C.14) were used. A 0.5-mm-thick dentin specimens and 1.4-mm-thick enamel/dentin specimens (n = 5) were obtained from anterior bovine maxillary teeth. Scattering, absorption, transmittance, and albedo coefficient were calculated using Kubelka-Munk's model. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (p < 0.001), and goodness-of-fit coefficient (GFC). Relative translucency parameter differences were evaluated using translucency thresholds. RESULTS: Reflectance, scattering, absorption, and transmittance properties were wavelength dependent. Good matches (GFC ≥ 0.999) in spectral reflectance were observed between 0.5-mm-thick dentin and 1.4-mm-thick enamel/dentin, and 3Y-NC.5 and 5Y-NC.5. Scattering was the main optical extinction process during light interaction with zirconia and dental structures, as indicated by albedo coefficient. Translucency differences were acceptable only for 3Y-NC.5 and the dentin structure, and 5Y-C.14 and the enamel/dentin structure. CONCLUSIONS: Optical properties of 3Y-TZP and 5Y-PSZ dental zirconia differed from each other and from bovine dental structures. Nevertheless, 3Y-TZP showed similar relative translucency parameter to bovine dentin. CLINICAL SIGNIFICANCE: To achieve the best esthetic results in restorative dentistry, it is crucial for clinicians to know about the optical properties of 3Y-TZP and 5Y-PSZ and to be able to compare these properties with those of dental structures.

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STATEMENT OF PROBLEM: Layered composite resins may adequately mask discolored substrates. However, whether color changes that occur over time affect masking ability is unclear. PURPOSE: The purpose of this in vitro study was to investigate the effect of layering and water aging on the masking ability of 2 composite resins. MATERIAL AND METHODS: Disk specimens (1.5 mm-thick and shade A1) from Charisma Diamond (CD) and Filtek Z350XT (Z350) were made according to the composite resin shade combination used in the layering strategies: bilayer for CD (enamel/dentin) and for Z350 (enamel/body and enamel/dentin) and trilayer for Z350 (enamel/body/dentin) (n=5). Color measurements were obtained with a spectrophotometer over an A3.5 ceramic substrate, and the whiteness index for dentistry (WID) was calculated. The specimens were aged in water at 37 °C and evaluated at different times: 24 hours, 1 week, 1 month, 2 months, 6 months, 12 months, 18 months, and 24 months. CIEDE2000 color differences (ΔE00) and WID differences (ΔWID) were calculated and interpreted by 50:50% color and whiteness perceptibility and acceptability thresholds. Changes among strategies and aging times were analyzed using the Kruskal-Wallis test (α=.05). Contrasts were made using the Mann-Whitney U test with Bonferroni correction (α=.001). RESULTS: ΔE00 decreased from 24 hours to 2 months of aging. From 2 months onwards, ΔE00 increased for all layering strategies and times, without significant changes in lightness for CD (P>.004). Overall, for the CD restorative system, an increase in ΔWID was observed after 1 month of aging (P<.001), while for the Z350 restorative system, ΔWID decreased after aging (P<.001), except for the Z350 bilayer strategy (enamel + dentin) at 1 week and 2 months (P>.004). For all layering strategies and aging times, color differences were higher than the 50:50% perceptibility threshold for ΔE00 and, after 6 months, higher than the 50:50% acceptability threshold for ΔE00 and the 50:50% whiteness acceptability threshold. CONCLUSIONS: The ability of the tested composite resins to mask a discolored substrate was affected by the layering approach applied and by prolonged water aging.

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OBJECTIVE: To evaluate the effect of layering strategy and substrate color on the masking ability of resin composites. MATERIALS AND METHODS: A1-shaded specimens from Charisma Diamond and Filtek Z350XT were produced using different layering strategies. Color measurements were made by a reflectance spectrophotometer over A2, C2, A3.5, C3, C4 substrates. Color differences were calculated and interpreted by the 50%:50% perceptibility and acceptability visual thresholds. Data was analyzed by Kruskal-Wallis and Dunn post hoc test. Chi-square test was used to determine the association between masking ability, and independent variables. RESULTS: Color differences were significantly lower on A2 and C2 in comparison with C4 for the majority of the layering strategies. Acceptable matches were observed on most of the combinations over A2. Moderately unacceptable mismatches were observed in most of the combinations over C2 and A3.5. Clearly unacceptable mismatches were observed on the C3 and C4. The ΔE00 color shifts were predominantly influenced by ΔL00 for all layering strategies and substrate colors. CONCLUSION: Masking ability was affected by the layering strategy and substrate color. Acceptable masking was associated with A2 and C2, and with layering strategy composed of 0.5 mm enamel opacity and 1.0 mm dentin opacity thicknesses, using the Filtek Z350XT. CLINICAL SIGNIFICANCE: Resin composites-shade A1-applied by different layering strategies with a final thickness of 1.5 mm were able to mask mild and moderately discolored substrates. Severely discolored substrates were not masked effectively.

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OBJECTIVE: Evaluate the effectiveness and color stability of bleaching techniques on blood-stained teeth. MATERIAL AND METHODS: The teeth were stained by blood and allocated to groups: walking bleach, inside/outside, and in-office bleaching. L*, a*, b*, C*, h° color coordinates were measured using a clinical spectrophotometer at baseline, weekly (T1-T2-T3), and at 1-week (T4), 6-months (T5), and 1-year (T6) follow-up evaluations. ΔEab* , ΔE00 , and ΔWID were calculated between sequential evaluation timepoints and between baseline and each evaluation timepoint. Color coordinates and WID differences in each timepoint and technique were analyzed by Wilcoxon Signed Rank, Kruskal-Wallis and Mann-Whitney U test, respectively. ΔEab* , ΔE00 , and ΔWID were interpreted by color visual thresholds. RESULTS: The techniques presented a significant increase in L* and WID and, a significant decrease in a* and b* until the completion of treatments. Statistical differences between the techniques for a*, b* and WID were observed from T1 until T3. All techniques demonstrated excellent effectiveness for ΔEab* , ΔE00 , and ΔWID between baseline and each evaluation and follow-up timepoints. However, at T6, it was possible to identify a rebound effect for all techniques. CONCLUSIONS: All bleaching techniques presented excellent effectiveness. The stability of the whitening produced was maintained for 6 months. CLINICAL SIGNIFICANCE: Effective whitening of blood-stained teeth was achieved using walking bleach (sodium perborate), inside/outside (hydrogen peroxide - 7.5%) and in-office techniques (hydrogen peroxide - 35%). The bleaching techniques were effective after the completion of the treatments. A slight rebound was observed at 1 year follow-up.

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OBJECTIVE: Evaluate the masking ability of bleach-shade resin composites applied by multilayering techniques over colored substrates. MATERIALS AND METHODS: Disc-shaped specimens were fabricated from bleach-shade resin composites using different multilayering techniques. Substrates were produced in opaque ceramic discs simulating colored substrates (A2, A3, A3.5, C2, C3, C4) and a bleached tooth (0M1). Color coordinates were obtained using a reflectance spectrophotometer. Color difference was calculated by CIEDE2000 using coordinates of 0 M1 ceramic as standard reference. Data were analyzed by one-way ANOVA and Tukey's post-hoc test (p ≤ 0.05). Masking ability interpretation was based on perceptibility and acceptability thresholds. RESULTS: All combinations presented ΔE00 above the acceptable threshold (ΔE00 >1.8), ranging from 2.49 to 7.42, regardless of the restorative system, multilayering strategy or substrate color. Multilayering combinations placed over A2, A3 and A3.5 were moderately (1.8<ΔE00 ≤3.6) and clearly unacceptable (3.6<ΔE00 ≤5.4), combinations associated with C2, C3 and C4 were clearly unacceptable and, extremely unacceptable (ΔE00 >5.4). Lower ΔE00 was observed for combinations with 0.5 mm extra white enamel layer (2.49), or 1.0 mm white dentin layer (2.69), over A2 and A3.5 substrates. Lightness difference showed the greatest contribution to ΔE00 . CONCLUSIONS: Bleach-shade resin composite systems applied by the multilayering technique were not able to ensure effective masking ability. CLINICAL SIGNIFICANCE: Bleach-shade resin composites applied with different combinations of the multilayering technique were not effective in masking colored substrates. Alternative strategies, techniques and dental materials should be explored to obtain acceptable masking.

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OBJECTIVE: To evaluate the influence of neutral color backgrounds on the perception of color differences in dentistry. METHODS: A software was developed for this study that calculated the perceptibility (PT) and acceptability (AT) thresholds of color differences between a pair of computer-simulated incisor samples (n = 60 pairs) over three neutral color (white, gray and black) backgrounds. CIELAB and CIEDE2000 color difference formulas were used. Five groups of volunteer observers (N = 100) participated in the psychophysical experiment (n = 20): Dentists; Dental students; Dental auxiliaries; Dental technicians; and Laypersons. The psychophysical experiment was performed in a dark environment on a calibrated high-resolution screen. To determine PT and AT values, the 60 pairs of samples were randomly presented to each observer over the different backgrounds. The data were adjusted (TSK Fuzzy) and analyzed statistically using Student t-test and ANOVA (α = 0.05). RESULTS: Regardless of the metric and the background used, the PT values showed no difference among different observers (p > 0.05). Dentists showed the lowest PT values. Dental technicians showed the lowest AT (p ≤ 0.05) and similar values for the three backgrounds (p > 0.05), regardless of the metric used. The other groups of observers showed the lowest and the highest AT values when using black and white backgrounds, respectively (p ≤ 0.05). CONCLUSIONS: The lowest AT values using a black background indicates that the use of this background allows for the evaluation of slight color differences, and should be used for challenging color differences in esthetic dentistry. This study showed the influence of the observer experience on color evaluation in dentistry. CLINICAL SIGNIFICANCE: There was no influence of the background color on the perceptibility threshold. However, dentists and dental technicians showed greater ability to perceive slight color differences compared to other groups of observers.

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OBJECTIVE: To evaluate color, lightness, chroma, hue, and translucency adjustment potential of resin composites using CIEDE2000 color difference formula. METHODS: Three resin composites (Filtek Universal, Harmonize, and Omnichroma) were tested. Two types of specimens were prepared: an outer base shade with an inner hole filled with test shades and single-composite specimens of all shades. Spectrorradiometric reflectances measurements and subsequent CIELAB color coordinates and translucency parameter (TP) were performed. Color (CAP00 ), lightness, chroma, hue, and translucency (TAP00 ) adjustment potential using CIEDE2000 color difference were computed. Color and transparency differences among composite materials and shades were statistically tested (P < 0.05). RESULTS: Positive CAP00 and TAP00 values were found for majority of tested materials. CAP00 values ranged from -0.14 to 0.89, with the highest values found for Omnichroma (>0.75 in all cases). TAP00 values ranged from -0.06 to 0.86 with significant translucency differences among dual and single specimens. Omnichroma exhibited the highest adjustment potential for all color dimensions studied. CONCLUSIONS: Lightness, hue, chroma, and translucency adjustment potential have been introduced using CIEDE2000 color difference formula, and have shown their usefulness to evaluate blending effect in dentistry. Color coordinates and translucency adjustment potential were dependent on dental material. Omnichroma exhibited the most pronounced blending effect. CLINICAL SIGNIFICANCE: Resin composites with increased color and translucency adjustment may simplify shade selection, making this process easier and less time consuming. Furthermore, these materials might facilitate challenging and complex color matching situations.

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Abstract The clinical features of COVID-19 differ substantially upon the presence (or absence) of viral pneumonia. The aim of this article was to describe the clinical characteristics of COVID-19 patients admitted to the Internal Medicine ward, as divided into those with and without pneumonia. This single-center prospective cohort study was conducted in a tertiary teaching public hospital in Buenos Aires City named Hospital General de Agudos Carlos G. Durand. Baseline data collection was performed within 48 hours of admission and patients were followed until discharge or in-hospital death. Epidemiological, clinical, laboratory, and radiological characteristics together with treatment data were obtained from the medical records. Of the 417 included, 243 (58.3%) had pneumonia. Median age was 43 years (IQR:32-57) and 222 (53.2%) were female. The overall crude case-fatality rate was 3.8%. None of the COVID-19 patients without pneumonia developed critical disease, required invasive mechanical ventilation nor died during hospitalization. However, 7 (4%) developed severe disease during follow-up. Among patients with COVID-19 pneumonia, in-hospital mortality rate was 6.6%, severe disease developed in 81 (33.3%), critical disease in 23 (9.5%), and 22 (9.1%) were admitted to the intensive care unit. A largely good prognosis was observed among COVID-19 patients without pneumonia, still, even among this group, unfavorable clinical progression can develop and should be properly monitored. Critical illness among patients with COVID-19 pneumonia was frequent and observed rates from this cohort provide a sound characterization of COVID-19 clinical features in a major city from South America.

Resumen Las características clínicas del COVID-19 difieren sustancialmente según la presencia (o ausencia) de neumonía viral. El objetivo de este artículo fue describir las características clínicas de los pacientes con COVID-19 internados en el servicio de Clínica Médica, divididos en pacientes con y sin neumonía. Fue un estudio de cohorte prospectivo, con base en un único centro, realizado en un hospital público de la ciudad de Buenos Aires: Hospital General de Agudos Carlos G. Durand. La recolección basal de datos se realizó dentro de las 48 horas del ingreso y los pacientes fueron seguidos hasta el alta o la muerte hospitalaria. Las características epidemiológicas, clínicas, de laboratorio y radiológicas junto con los datos del tratamiento se obtuvieron de la historia clínica. De los 417 incluidos, 243 (58.3%) tenían neumonía. La mediana de edad fue de 43 años (RIC: 32-57) y 222 (53.2%) eran mujeres. La tasa global de letalidad fue del 3.8%. Ninguno de los pacientes con COVID-19 sin neumonía desarrolló enfermedad crítica, requirió ventilación mecánica invasiva ni falleció durante la hospitalización. Sin embargo, 7 (4%) desarrollaron enfermedad grave durante el seguimiento. Entre aquellos con neumonía COVID-19, la tasa de mortalidad hospitalaria fue del 6.6%, se desarrolló enfermedad grave en 81 (33.3%), enfermedad crítica en 23 (9.5%) y 22 (9.1%) fueron trasladados a la unidad de cuidados intensivos. Los pacientes con COVID-19 sin neumonía presentaron buen pronóstico; sin embargo, incluso en este grupo, se observaron algunos con progresión clínica desfavorable, por lo que se requirió seguimiento adecuado. En los pacientes con neumonía por COVID-19, el desarrollo de enfermedad crítica fue frecuente y las tasas observadas en esta cohorte proporcionan una caracterización sólida de las características clínicas de los pacientes con COVID-19 en una importante ciudad de América del Sur.

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INTRODUCCIÓN: Conocer los predictores de mala evolución en pacientes con Enfermedad por Coronavirus 2019 (COVID-19) permite identificar de forma temprana a los pacientes con peor pronóstico, aportando mejores herramientas a la hora de tomar decisiones clínicas. Se presenta el protocolo de un estudio de cohorte cuyo objetivo principal es identificar factores de riesgo de infección severa, critica y mortalidad en pacientes con COVID-19 internados en el Servicio de Clínica Médica del Hospital Durand (Buenos Aires, Argentina). MÉTODOS: Estudio de cohorte prospectivo con base en un único centro. Se incluirá a todos los pacientes que ingresen al servicio de Clínica Médica con diagnóstico de COVID-19 durante el periodo de estudio. Se recolectarán las características epidemiológicas, clínicas, de laboratorio, radiológicas y los datos de tratamiento, al ingreso y al momento del alta o muerte hospitalaria. El evento final primario es la muerte en la internación; los eventos secundarios son el desarrollo de enfermedad grave y enfermedad crítica, la internación en unidad cerrada y el requerimiento de asistencia respiratoria mecánica.

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The clinical features of COVID-19 differ substantially upon the presence (or absence) of viral pneumonia. The aim of this article was to describe the clinical characteristics of COVID-19 patients admitted to the Internal Medicine ward, as divided into those with and without pneumonia. This single-center prospective cohort study was conducted in a tertiary teaching public hospital in Buenos Aires City named Hospital General de Agudos Carlos G. Durand. Baseline data collection was performed within 48 hours of admission and patients were followed until discharge or in-hospital death. Epidemiological, clinical, laboratory, and radiological characteristics together with treatment data were obtained from the medical records. Of the 417 included, 243 (58.3%) had pneumonia. Median age was 43 years (IQR:32-57) and 222 (53.2%) were female. The overall crude case-fatality rate was 3.8%. None of the COVID-19 patients without pneumonia developed critical disease, required invasive mechanical ventilation nor died during hospitalization. However, 7 (4%) developed severe disease during follow-up. Among patients with COVID-19 pneumonia, in-hospital mortality rate was 6.6%, severe disease developed in 81 (33.3%), critical disease in 23 (9.5%), and 22 (9.1%) were admitted to the intensive care unit. A largely good prognosis was observed among COVID-19 patients without pneumonia, still, even among this group, unfavorable clinical progression can develop and should be properly monitored. Critical illness among patients with COVID-19 pneumonia was frequent and observed rates from this cohort provide a sound characterization of COVID-19 clinical features in a major city from South America.

Las características clínicas del COVID-19 difieren sustancialmente según la presencia (o ausencia) de neumonía viral. El objetivo de este artículo fue describir las características clínicas de los pacientes con COVID-19 internados en el servicio de Clínica Médica, divididos en pacientes con y sin neumonía. Fue un estudio de cohorte prospectivo, con base en un único centro, realizado en un hospital público de la ciudad de Buenos Aires: Hospital General de Agudos Carlos G. Durand. La recolección basal de datos se realizó dentro de las 48 horas del ingreso y los pacientes fueron seguidos hasta el alta o la muerte hospitalaria. Las características epidemiológicas, clínicas, de laboratorio y radiológicas junto con los datos del tratamiento se obtuvieron de la historia clínica. De los 417 incluidos, 243 (58.3%) tenían neumonía. La mediana de edad fue de 43 años (RIC: 32-57) y 222 (53.2%) eran mujeres. La tasa global de letalidad fue del 3.8%. Ninguno de los pacientes con COVID-19 sin neumonía desarrolló enfermedad crítica, requirió ventilación mecánica invasiva ni falleció durante la hospitalización. Sin embargo, 7 (4%) desarrollaron enfermedad grave durante el seguimiento. Entre aquellos con neumonía COVID-19, la tasa de mortalidad hospitalaria fue del 6.6%, se desarrolló enfermedad grave en 81 (33.3%), enfermedad crítica en 23 (9.5%) y 22 (9.1%) fueron trasladados a la unidad de cuidados intensivos. Los pacientes con COVID-19 sin neumonía presentaron buen pronóstico; sin embargo, incluso en este grupo, se observaron algunos con progresión clínica desfavorable, por lo que se requirió seguimiento adecuado. En los pacientes con neumonía por COVID-19, el desarrollo de enfermedad crítica fue frecuente y las tasas observadas en esta cohorte proporcionan una caracterización sólida de las características clínicas de los pacientes con COVID-19 en una importante ciudad de América del Sur.

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OBJECTIVE: To evaluate the masking ability of different indirect restorative systems (IRS) on tooth-colored resin substrates. METHODS: A1-shaded specimens from 5 IRS (LDC-IPS e.max® CAD; YZW-Zenostar Zr Translucent; PICN-Enamic; YLD-T-IPS e.max® ZirCAD + IPS e.max Ceram; CAD-on-Zenostar Zr Translucent + Crystall./Connect + IPS e.max® CAD) were fabricated. Specimens (n = 5) were cemented with a resin luting agent (Variolink® N; shade White) on three different shades (ND3, ND8 and ND9) of a tooth-colored resin substrate (IPS Natural Die Material). Spectral reflectance and color coordinates were measured using a spectroradiometer under standardized lighting conditions (CIE D65 illumination) and optical geometry 0/45°. Color differences (ΔEab* and ΔE00) from cemented specimens and CIELAB- and CIEDE2000-based translucency parameter (TP and TP00) from non-cemented specimens were calculated. Data was statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). ΔE values were also analyzed using perceptibility (PT = 1.22 ΔEab* units; 0.81 ΔE00 units) and acceptability (AT = 2.66 ΔEab* units; 1.77 ΔE00 units) thresholds. RESULTS: The cemented specimens of CAD-on, LDC, YZW and PICN on different substrates (ND3-ND8, ND3-ND9 and ND8-ND9) showed different ΔEab* and ΔE00 values (p ≤ 0.05), which were above AT. YLD-T showed ΔEab* and ΔE00 values below AT for all comparisons. Lowest and highest TP and TP00 values were obtained for YLD-T and PICN, respectively (p ≤ 0.05). SIGNIFICANCE: Resin-cemented YLD-T on different tooth-colored substrates showed less translucency as well as smaller color differences (below acceptability threshold), indicating the best masking ability among evaluated systems.

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OBJECTIVE: Accuracy on visual shade matching (VSM) is one of the most difficult procedures in esthetic dentistry. Some variables can influence on this process and gender is one of the most controversial. This observational study evaluated the influence of gender on accuracy of VSM. MATERIALS AND METHODS: One-hundred observers (65 females and 35 males) shade matched four human upper central incisors (UCI) to shade tabs from Vita Classical (VC) shade guide. In addition, the spectral reflectance values from the four UCI and from the 16 VC shade tabs were measured using a spectroradiometer (SP). Measurements were performed over a gray background, inside a viewing booth and under D65 illuminant (diffuse/0º geometry). CIELAB coordinates (L*, a*, and b*) were calculated according to CIE D65 illuminant and CIE 2º Standard Observer. Instrumental shade matching for each UCI, based on minimum color difference, was performed using two color difference metrics (CIELAB and CIEDE2000(2:1:1)). Data was analyzed using descriptive statistics and McNemar test (α = 0.05). RESULTS: Irrespective of the color difference metric, the most prevalent shade performed by females showed greater success (50% for CIELAB and 100% for CIEDE2000(2:1:1)) than males (25% for CIELAB and 50% for CIEDE2000(2:1:1)). However, such difference on gender was statistically significant only when using CIEDE2000(2:1:1) color difference metric (p ≤ 0.05). CONCLUSIONS: The most prevalent shade option resultant from VSM performed by females using VC shade guide perfectly agreed (100% success rate) with measurements from SP and CIEDE2000(2:1:1) color difference metric. CLINICAL SIGNIFICANCE: The ability to understand and distinguish color differences in VSM is critical in clinical dentistry. Variation in shade perception due to observer gender can be minimized using additional observers and/or improving shade matching ability. (J Esthet Restor Dent 29:E15-E23, 2017).

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OBJECTIVES: To analyze the influence of lightness, chroma and hue differences on visual shade matching performed by dental students. METHODS: 100 dental students (DS) volunteers with normal vision participated in the study. A spectroradiometer (SP) was used to measure the spectral reflectance of 4 extracted human upper central incisors (UCI 1-4) and shade tabs from Vita Classical (VC) and Vita Toothguide 3D-Master (3D) shade guides. Measurements were performed over a gray background, inside a viewing booth and under D65 illuminant (diffuse/0° geometry). Color parameters (L*, a*, b*, C* and h°) were calculated. DS used VC and 3D to visually select the best shade match for each UCI. CIE metric differences (Δa*,Δb*,ΔL', ΔC' and ΔH') and CIEDE2000(2:1:1) lightness (ΔEL), chroma (ΔEC) and hue (ΔEH) differences were obtained from each UCI and the first three shades selected by DS and the first option using CIELAB, CIEDE2000(1:1:1) and CIEDE2000(2:1:1) color difference metrics. The closest CIELAB color-discrimination ellipsoid (from RIT-DuPont visual color-difference data) to each UCI was selected for the analysis of visual shade matching. RESULTS: DS showed a preference for shades with lower chroma (ΔC' and ΔEC) and/or hue (ΔH' and ΔEH) values instead of shades with lower lightness values (ΔL' and ΔEL). Most best visual matches were near the tolerance ellipsoid centered on tooth shade. SIGNIFICANCE: This study is an attempt to partially explain the inconsistencies between visual and instrumental shade matching and the limitations of shade guides. Visual shade matching was driven by color differences with lower chroma and hue values.

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Se presentan dos sistemas de ejercicios para complementar las actividades de práctica oral y escritura de cada una de las unidades del libro Kernel II. Se muestran alrededor de 180 ejercicios con el objetivo de permitir que los profesores puedan seleccionar los que les sean útiles para enfrentar las necesidades de sus estudiantes

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Se hace un breve recuento de las características fundamentales de las etapas de evolución histórica de la lucha antituberculosa en Cuba. Se destacan las bases y las medidas aplicadas para su control. Se hace una síntesis de los esquemas terapéuticos utilizados en los últimos 20 años y la tendencia de las notificaciones de casos nuevos en el decenio 1979-1988 en el que hubo una reducción de 38,8

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Se hace un breve recuento de las características fundamentales de las etapas de evolución histórica de la lucha antituberculosa en Cuba. Se destacan las bases y las medidas aplicadas para su control. Se hace una síntesis de los esquemas terapéuticos utilizados en los últimos 20 años y la tendencia de las notificaciones de casos nuevos en el decenio 1979-1988 en el que hubo una reducción de 38,8 por ciento

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