ABSTRACT Objective: To evaluate the dimensional change of edentulous models made of high density laboratory silicones at different storagetimes. Methods: A metallic master model simulating an edentulous maxilla was used. The model had projections of 1.8 cm located in the regions of canines (A and B) and molars (C and D) allowing the linear measurement of distances AB, BC, CD, DA, AC and BD. A laboratory silicone mold was made for duplication of master model in the following materials (n = 10): G1: Zetalabor 85, G2: Titanium 95, G3: Platinum 95 and G4: Gypsum type III (control). The samples were photographed and measured using a software (Image J) at times T1 (baseline) and T2 (after one week of models fabrication). The data were statistically analyzed using Kruskal- Wallis and Dun non-parametric tests (α = 0.05). Results: The storage time influenced the behavior of the materials evaluated. All groups presented dimensional changes in both times and the group Tit95 presented the best results. Only Zet85 group showed a different behavior related to the region of the model. Conclusions: The high density laboratory silicones showed satisfactory results when compared to the gypsum group. Tit95 was the most stable material and it can be recommended as an edentulous model for total protheses.

RESUMO Objetivo: Avaliar a alteração dimensional de modelos edêntulos fabricados em silicone laboratorial de alta densidade em diferentes tempos de armazenagem. Métodos: Um modelo mestre metálico simulando uma maxila edêntula foi utilizado. O modelo possuía projeções oclusais de 1,8 cm localizadas nas regiões de caninos (A e B) e molares (C e D), permitindo a mensuração das distâncias lineares AB, BC, CD, DA, AC e BD. Um molde foi fabricado em silicone laboratorial para duplicação do modelo mestre com os seguintes materiais (n = 10): G1: Zetalabor 85, G2: Titanium 95, G3: Platinum 95 e G4: Gesso tipo III (controle). As amostras foram fotografadas e mensuradas com auxílio de um software (Image J) nos tempos T1 (baseline) e T2 (após uma semana de confecção). Os dados obtidos foram avaliados estatisticamente utilizando os testes não paramétricos de Kruskal- Wallis e Dunn (α = 0.05). Resultados: O tempo de armazenagem influenciou o comportamento dos materiais avaliados. Todos os grupos apresentaram alterações dimensionais em ambos os temos de avaliação e o G2 apresentou os melhores resultados. Apenas o grupo G1 mostrou alteração dimensional dependente da região mensurada. Conclusão: Silicones laboratoriais de alta densidade mostraram resultados satisfatórias de alteração dimensional quando comparados ao gesso tipo III. O material Titanium 95foi o mais estável e pode ser recomendado como alternativa para a confecção de modelos edêntulos.

ABSTRACT Objective: This study assessed whether the use of a silane coupling agent influence the bond strength of two universal adhesives to ceramic or resin CAD/CAM blocks. Methods: Forty-eight samples were obtained from each resin nano-ceramic hybrid block (RCBs) and lithium disilicate ceramic blocks (LD). Samples were treated with silane with MDP (Monobond - S-MDP), silane without MDP (Prosil - PS), and no silane application (Control - Ctr) followed by universal adhesive with silane (UAS) and without silane (UA) (n=8). Three polyurethane tubes (1.5 mm of internal diameter) were positioned in each sample treated surface and filled with a dual cured resin cement. Bond strength was assessed by microshear bond strength test and failure analysis was performed for all samples. Results: For the RCBs, UAS presented the highest bond strength values (p=0.004). Silane application was not significant in bond strength values (p=0.444). For LD, silane application was significant in bond strength values (p<0.001), but the adhesive was not (p=0.066). Failure analysis showed high prevalence of adhesive failures for both substrates. Conclusion: A silane-containing universal adhesive promoted the best bond strength results to the resin nano-ceramic hybrid block. For bonding to a glass-ceramic CAD/CAM material, additional silane (without MDP) application presented the best results.

RESUMO Objetivo: Este estudo avaliou se o uso de um agente de união silano influencia na resistência de união de dois adesivos universais a blocos CAD/CAM cerâmicos ou resinosos. Métodos: Quarenta e oito amostras foram obtidas de blocos resinosos (RCBs) e cerâmicos de dissilicato de lítio (LD). As amostras foram tratadas com silano contendo: MDP (Monobond - S-MDP), silano sem MDP (Prosil - PS) ou sem aplicação de silano (Control - Ctr) seguido de adesivo universal com silano (UAS) ou sem silano (UA) (n=8). Três tubos de poliuretano (1,5 mm de diâmetro interno) foram posicionados em cada superfície tratada da amostra e preenchidos com um cimento resinoso dual. A resistência de união foi avaliada pelo teste de microcisalhamento e a análise de falha foi realizada para todas as amostras. Resultados: Para os RCBs, UAS apresentou os maiores valores de resistência de união (p=0,004). A aplicação de silano não foi significativa nos valores de resistência adesiva (p=0,444). Para LD, a aplicação de silano foi significativa nos valores de resistência de união (p<0,001), mas o adesivo não (p=0,066). A análise de falhas mostrou alta prevalência de falhas adesivas para ambos os substratos. Conclusão: O adesivo universal contendo silano promoveu os melhores valores de resistência adesiva ao bloco de resina. Para o bloco cerâmico, a aplicação adicional de silano (sem MDP) apresentou melhores resultados.

RESUMO Objetivo Avaliar a associação entre a composição corporal de crianças e adolescentes com a renda familiar. Métodos Estudo transversal, foram incluídos participantes entre 5 e 19 anos. As variáveis socioeconômicas foram avaliadas por meio de questionário padronizado. As variáveis de desfecho foram escore Z do índice de massa corporal e parâmetros de bioimpedância (massa muscular esquelética, massa livre de gordura e percentual de gordura) e variáveis preditoras (idade, sexo, raça, local de residência, escolaridade do pai, peso ao nascer e aleitamento materno) foram analisados pelo modelo de regressão quantílica e são apresentados os dados do percentil 50. Os testes foram bidirecionais, e as diferenças foram consideradas significativas com p<0,05. Resultados Entre os 529 participantes incluídos, 284 (53,6%) eram do sexo feminino e a média de idade foi de 11,41±3,9 anos. O escore Z do índice de massa corporal foi o único desfecho que não apresentou diferenças entre os sexos (p=0,158). No modelo bruto, uma menor renda familiar foi associada a menor massa muscular esquelética (Diferença= -7,70; IC 95% -9,32 a -5,89), p<0,001), menor massa livre de gordura (Diferença= -13,40; IC 95% -16,40 a -10,39, p<0,001) e o menor percentual de gordura associou-se à menor renda familiar (Diferença= -5,01, IC 95% -9,91 a -0,11, p=0,027). O escore Z do IMC não foi associado à renda familiar. Conclusão A renda familiar está diretamente associada à menor massa magra, ao percentual de gordura e à massa muscular esquelética em crianças e adolescentes.

ABSTRACT Objective To evaluate the association between children and adolescents’ body composition with family income. Methods Cross-sectional study, participants between 5 and 19 years were included. A standardized questionnaire assessed socioeconomic variables. The outcome variables were z-score of Body Mass Index and bioimpedance parameters (skeletal muscle mass, fat-free mass, and fat percentage) and predictor variables (age, sex, race, place of residence, father’s education, birth weight and breastfeeding) were analyzed using the quantile regression model and data from the 50th percentile are presented. The tests were bidirectional and the differences were considered significant with p<0.05. Results Among the 529 participants included, 284 (53.6%) were female and the mean age was 11.41±3.9 years. The Body Mass Index z-score was the only outcome that did not show differences between sexes (p=0.158). In the crude model, lower family income was associated with lower skeletal muscle mass (Difference=-7.70; 95% CI -9.32 to -5.89), p<0.001), lower fat-free mass (Difference= -13.40; 95% CI -16.40 to -10.39, p<0.001) and the lowest percentage of fat was associated with lower family income (Difference= -5.01, 95% CI -9.91 to -0.11, p=0.027). The z-score of BMI was not associated with family income. Conclusion Family income is directly associated with lower fat-free mass, fat percentage, and skeletal muscle mass in children and adolescents.

Abstract Objectives: The aim of this study was to estimate the percentage distribution of body composition parameters for healthy people at different ages from the assessment of electrical bioimpedance. Methods: A cross-sectional study of healthy Brazilian aged 5 years and older. Were evaluated: total body fat; percent body fat; fat-free mass; percent lean mass; fat mass index; and fat-free mass index. Results: Of 1240 participants, with a median age of 27.0 years, 52.5% were female, and 73.7% were Caucasian. Most of the body composition variables were associated with age. The fat-free mass increased from youth to adult and decreased in the elderly in both sexes, with higher values in males than in females. In males, the percentage of lean mass has higher values in adolescence compared to childhood, and in adults compared to the elderly, when analyzed from the 50th percentile. In women, fat-free mass compared to adulthood, values were higher in childhood and lower in older ages. Conclusions: The study is the first to describe the Brazilian reference values for most clinical parameters of bioimpedance in percentiles stratified by different life cycles and sex. These findings can be very useful in clinical practice for health promotion and monitoring the nutritional status of the individual.

ABSTRACT: This study aimed to compare the trueness and precision of physical models manufactured chairside (intraoral scanner and 3D printed) or by plaster models obtained using impression with alginate or addition silicone. A full- arch stainless steel die was impressed to obtain ten physical models for each group. The models were measured in a stereomicroscope, considering four linear distances. To assess the precision accuracy, an analysis of the measurement variability was carried out, identified by the coefficients of variation and by the Levene’s test to compare the groups. To analyze trueness, the data average was subtracted from the database and compared considering alpha as 5 %. Considering precision, the higher dispersion of data occurred in the models obtained with silicone impression. And for trueness, Kruskal Wallis and Dunn tests results did not indicate differences between the groups in the anteroposterior linear distances (p> 0.05). Only in anterior transverse distance obtained through TRIOS (0.31 mm), it presented lower accuracy compared to the models from silicone impression (0.13 mm); however, at transverse posterior distance, the models from silicone impression showed the lowest accuracy (p <0.05). There was no difference between the models from scanning (p> 0.05). The physical dental models obtained by digital and analog workflows showed acceptable dimensional accuracy expressed by high precision and trueness. There is no difference between the evaluated intraoral scanner systems and the impression materials for the full-arch impression.

RESUMEN: Este estudio tuvo como objetivo comparar la veracidad y precisión de modelos físicos fabricados en la clínica dental (escáner intraoral e impreso en 3D) o por modelos de yeso obtenidos mediante impresión con alginato o silicona de adición. Una matriz de acero inoxidable de arco completo fue impresa para obtener diez modelos físicos para cada grupo. Los modelos se midieron en un estereomicroscopio, considerando cuatro distancias lineales. Se realizó un análisis de la variabilidad de la medida para evaluar la precisión, identificada por los coeficientes de variación y por la prueba de Levene para comparar los grupos. Para analizar la veracidad, el promedio de los datos se restó de la base de datos y se comparó considerando alfa como 5 %. Considerando la precisión, la mayor dispersión de datos ocurrió en los modelos obtenidos con impresión de silicona. Y para la veracidad, los resultados de las pruebas de Kruskal Wallis y Dunn no indicaron diferencias entre los grupos en las distancias lineales anteroposteriores (p> 0,05). Solo en la distancia transversal anterior obtenida mediante TRIOS (0,31 mm) presentó menor precisión en comparación con los modelos de impresión de silicona (0,13 mm); sin embargo, la distancia transversal posterior, los modelos de impresión de silicona mostraron la menor precisión (p <0,05). No hubo diferencia entre los modelos de escaneo (p> 0,05). Los modelos dentales físicos obtenidos mediante flujos de trabajo digitales y analógicos mostraron una precisión dimensional aceptable expresada por alta precisión y veracidad. No se observó diferencia entre los sistemas de escáner intraoral evaluados y los materiales de impresión para la impresión de arco completa.

Resumo A revascularização endodôntica pode ser um tratamento alternativo para dentes imaturos necrosados, porém, várias etapas do tratamento podem causar alteração de cor dental. Este estudo avaliou o uso de três cimentos a base de silicato de cálcio com diferentes agentes radiopacificadores na alteração de cor (∆E) de pré-molares extraídos após a simulação de revascularização. Quarenta pré-molares unirradiculares extraídos foram conformados com brocas gates glidden #1-6, irrigados com hipoclorito de sódio, e preenchidos com sangue humano fresco. Três cimentos a base de silicato de cálcio com diferentes agentes radiopacificadores (óxido de bismuto - CSBi, tungstato de cálcio - CSW, e óxido de zircônio - CSZr) foram aplicados sobre o coágulo sanguíneo (n=10). O grupo controle recebeu a aplicação de um cimento temporário a base de óxido de zinco (TFZn) (n=10). ∆E foi medida com um espectrofotômetro, utilizando o sistema de cor L*a*b* da International Commission on Illumination (CIELab), em tempos diferentes: previamente ao preparo da cavidade de acesso (t0); logo após o tratamento (t1); e após um (t2), dois (t3), três (t4) e quatro (t5) meses. O local do dente para a avaliação de cor foi padronizado por uma matriz de silicone, a leitura da cor foi realizada 3 vezes por dente, e os dentes foram armazenados em água a 37ºC entre as avaliações. ∆E, ‘clareamento’ (índice WID) e tom amarelado (b*) foram avaliados. Os dados foram submetidos ao teste de ANOVA um fator e teste ANOVA de medidas repetidas, seguidos pelo teste post hoc de Tukey (α=0,05). Todos os grupos foram semelhantes em ∆E1 (t0-t1). A ∆E foi menor e constante no grupo controle. Em todos os tempos de avaliação, CSBi apresentou os maiores valores de ∆E (p<0.01). CSW e CSZr foram semelhantes em todos os tempos avaliados e apresentaram valores intermediários de ∆E. O índice WID de CSBi e CSW se distanciaram mais da referência ‘branco’. CSBi apresentou maior diminuição no tom amarelado (valor de b*) os outros grupos. O cimento contendo óxido de bismuto apresentou os maiores valores de alteração de cor. Todos os cimentos testados apresentaram alteração de cor clinicamente perceptível. O tungstato de cálcio e óxido de zircônio podem ser usados como radiopacificares alternativos para a diminuição da alteração de cor dental após o processo de revascularização endodontica.

Abstract The endodontic revascularization may be an alternative treatment for necrotic immature teeth, however, several treatment steps may cause tooth discoloration. This study evaluated the use of three calcium silicate-based cements with different radiopacifying agents on the color alteration (∆E) of extracted premolars after simulation of revascularization. Forty single rooted extracted premolars were shaped with #1-6 gates Glidden drills, rinsed with sodium hypochlorite, and filled with fresh human blood. Three calcium silicate-based cements with different radiopacifying agents (bismuth oxide - CSBi, calcium tungstate - CSW, and zirconium oxide - CSZr) were applied over the blood clot (n=10). The control group received the application of a temporary zinc oxide-based cement (TFZn) (n=10). ∆E was measured with a spectrophotometer, using the L*a*b* color system of the International Commission on Illumination (CIELab), in different times: prior to the preparation of the access cavity (t0); right after treatment (t1); and after one (t2), two (t3), three (t4) and four (t5) months. The tooth site for color evaluation was standardized by silicon matrix, the color reading was performed 3 times per tooth, and the teeth were stored in 37º water between evaluations. ∆E, whiteness (WID index) and yellowness (b*) were evaluated. Data were subjected to one-way ANOVA and repeated measures ANOVA, followed by Tukey’s post hoc test (α=0.05). All groups were similar in ∆E1 (t0-t1). The ∆E was the lowest and constant in the control group. In all evaluation times, CSBi presented the highest ∆E (p<0.01). CSW and CSZr were similar in all evaluated times and presented intermediate ∆E values. WID index from CSBi and CSW presented more distancing from ‘white’ reference. CSBi presented the greatest decrease in yellowness (b* value). The cement containing bismuth oxide presented the highest color alteration values. All tested calcium silicate-based cements presented clinically perceptible discoloration. Calcium tungstate and zirconium oxide may be used as alternative radiopacifiers to decrease tooth discoloration after endodontic tooth revascularization.

Abstract Objective: The aim of the present study was to evaluate the agreement between the most used skinfold thickness equations with multi-frequency bioimpedance analysis in the prediction of body fat levels in children. Method: A cross-sectional study of healthy Brazilian community-dwelling individuals. The anthropometric assessment included height, body mass, arm circumference, and waist circumference. The percentage of body fat was obtained by measuring skinfold thickness equations and using bioimpedance analysis, and skinfold thickness was measured using a scientific skinfold caliper. Bland-Altman plot analysis was used to verify the agreement between the methods. Results: There were 439 children and adolescents evaluated, with a mean age of 11.6 ± 3.7 years. The mean body fat by bioimpedance analysis was 22.8% ± 10.4%, compared to 22.4% ± 8.8% by Slaughter (1), 20.4% ± 9.2% by Slaughter (2), 19.6% ± 4.4% by Goran, and 24.7% ± 10.0% by Huang equations. Bland-Altman plot analysis revealed limits of agreement greater than 8% between the bioimpedance analysis approach and equations, exceeding the clinically acceptable limit predefined a priori. None of the equations had good agreement with bioimpedance analysis. Conclusion: It was concluded that skinfold thickness and bioimpedance analysis should not be used interchangeably in children and adolescents.

ABSTRACT The aim of this study was to verify the effectiveness of alternative techniques for measuring the linear dimensional change of molds obtained by different impression materials. A stainless-steel die containing three lines was used to get the impressions. The impression materials were handled according to the manufacturers' instructions. After gelation/polymerization time, the molds (n=12) were stored for 30 minutes and the lines were subsequently measured using: a microscope (Olympus Measuring Microscope STM; Olympus Optical Co) with a 30x magnification (MM, control group), a digital caliper (Mitutoyo Digimatic; Kawasaki) (DC) and digitization using a digital camera (Canon EOS Rebel 3Ti; Canon) (DI). For each mold, a mean of the length of the lines was obtained. For each impression material, the difference in the length between the metallic matrix and the mold was considered as linear dimensional change (%). The data were submitted to the non-parametric Kolmogorov-Smirnov test, followed by one-way Analysis of Variance (ANOVA) for each material, and the means were compared by the Tukey test (α=0.05). The DI group promoted values of dimensional accuracy without significant differences with the control group (MM), except for the putty-body condensation silicone. The DC group showed significant differences for MM and DI groups for all impression materials tested. The DI group showed to be a reliable methodology (Standard error of the mean <10%) to measure the linear dimensional change of all impression materials. The DI group presented molds with linear dimensional change values without significant differences with MM group, except for the putty-body addition silicone. The digitization is a reliable methodology to evaluate the linear dimensional changes of molds made with impression materials, except for the putty-body elastomeric impression materials.

Abstract Regulatory T (Treg) cells can suppress antitumor immune response, but little is known about possible age-related differences in the number of these cells in the microenvironment of oral tongue squamous cell carcinoma (OTSCC). The aim of this study was to determine the number of FoxP3+ Treg cells in the microenvironment of OTSCC in young (≤ 45 years) and older (≥ 60 years) patients, and to correlate the findings with clinicopathological parameters (sex, tumor size/extent, regional lymph node metastasis, clinical staging, and histopathological grade of malignancy). Forty-eight OTSCCs (24 diagnosed in young patients and 24 diagnosed in older patients) were selected. Lymphocytes exhibiting nuclear immunopositivity for FoxP3 were quantified at the tumor invasive front and the results were analyzed statistically using the non-parametric Mann-Whitney test. FoxP3+ lymphocytes were observed in all cases assessed. The number of FoxP3+ lymphocytes in OTSCC tended to be higher in older patients (p = 0.055). Analysis of OTSCC in males and in early clinical stages revealed a higher number of Treg cells in older patients than in young ones (p < 0.05). In older patients, the number of Treg cells tended to be higher in smaller tumors (p = 0.079). Tumors with intense inflammatory infiltrate exhibited a larger number of Treg cells, both in young (p = 0.099) and older patients (p = 0.005). The results suggest a greater participation of Treg cells in immunoinflammatory responses in the microenvironment of OTSCC in older patients, particularly in males and in early stages.

Abstract The aim of this study was to evaluate the immunoexpression of human leukocyte antigen-DR (HLA-DR) in actinic cheilitis (AC) and lower lip squamous cell carcinoma (LLSCC), and to correlate the findings with clinical (tumor size/extent, regional lymph node metastasis, and clinical stage) and histopathological (grade of epithelial dysplasia and inflammatory infiltrate for AC and histopathological grade of malignancy for LLSCC) parameters. Twenty-four AC and 48 LLSCC cases (24 with regional nodal metastasis and 24 without regional nodal metastasis) were selected. The scores of immunopositive cells for HLA-DR in the epithelial component of the lesions were assessed and the results were analyzed statistically using the nonparametric Mann-Whitney test. Epithelial expression of HLA-DR was observed in only five (20.8%) cases of AC (two low-grade and three high-grade lesions), with a very low median score of immunopositivity. By contrast, expression of HLA-DR was found in most LLSCC (97.9%), with a relatively high median score of positive cells. The score of HLA-DR-positive cells tended to be higher in tumors with regional lymph node metastasis, tumors in advanced clinical stages, and low-grade tumors, but the difference was not statistically significant (p > 0.05). In addition, there was a tendency towards higher expression of HLA-DR in highly/moderately keratinized tumors, and tumors with little/moderate nuclear pleomorphism (p > 0.05). The results suggest a potential role of HLA-DR in lip carcinogenesis, particularly in the development and progression of LLSCC. The expression of this protein can be related to the degree of cell differentiation in these tumors.

Introdução: A ocorrência de um vólvulo do sigmoide na criança é raro, constituindo desta forma um desafio diagnóstico. A identificação precoce desta patologia é essencial pois permite que a redução do vólvulo seja efetuada numa primeira abordagem por métodos não cirúrgicos, e quanto mais precoce na história da doença maior a taxa de sucesso e menor o risco de complicações associadas. Métodos/Conclusões: No entanto a cirurgia eletiva posterior é mandatória pelo alto risco de recidiva. Os autores apresentam o caso de uma adolescente sem antecedentes patológicos de relevo com um vólvulo sigmoideu recorrente submetido a redução endoscópica com sucesso.

Background: Sigmoid volvulus is a rare condition in children. Early diagnosis increases the success of nonsurgical treatment in the emergency department, but posterior elective surgery is important due to the risk of recurrence. Methods/Conclusions: We present the case of a healthy 16-yearold girl with recurrent volvulus and successful endoscopic treatment followed by elective surgery.

Abstract The aim of this study is to evaluate the action of paramonochlorophenol associated with Furacin followed by calcium hydroxide (CH) dressing in the control of inflammatory root resorption in cases of immediate tooth replantation with delayed endodontic treatment. A total of 28 incisors of 3 male dogs were extracted and replanted after 15 minutes, and randomly divided into 3 groups: Group I (n = 8) - endodontic treatment was performed before the extraction and replantation; Group II (n = 10) - endodontic treatment was performed 30 days after replantation and the root canal was filled with CH dressing; Group III (n = 10) - endodontic treatment was performed 30 days after replantation and root canals received temporary medication of paramonochlorophenol-Furacin followed by CH dressing. The animals were euthanized 90 days after replantation. The histomorphological events analyzed at the epithelial reattachment site were the intensity and extent of acute and chronic inflammatory processes, periodontal ligament (PDL) organization, the intensity and extent of acute and chronic inflammatory processes in the PDL space, root resorption, bone tissue, and ankylosis. Data were submitted to the Wilcoxon Signed Ranks Test for group comparison (α = 5%). In Groups I, II and III the periodontal ligament was regenerated and most of the resorption areas were repaired by newly formed cementum. The depth and extent of root resorption were significantly higher in Group II than in Group III. The use of paramonochlorophenol-furacin followed by CH dressing was more effective in controlling inflammatory root resorption after immediate tooth replantation.

Abstract This study aimed to investigate slow crack growth (SCG) behavior of a zirconia ceramic after grinding and simulated aging with low-temperature degradation (LTD). Complementary analysis of hardness, surface topography, crystalline phase transformation, and roughness were also measured. Disc-shaped specimens (15 mm Ø × 1.2 mm thick, n = 42) of a full-contour Y-TZP ceramic (Zirlux FC, Amherst) were manufactured according to ISO:6872-2008, and then divided into: Ctrl – as-sintered condition; Ctrl LTD – as-sintered after aging in autoclave (134°C, 2 bar, 20 h); G – ground with coarse diamond bur (grit size 181 μm); G LTD – ground and aged. The SCG parameters were measured by a dynamic biaxial flexural test, which determines the tensile stress versus stress rate under four different rates: 100, 10, 1 and 0.1 MPa/s. LTD led to m-phase content increase, as well as grinding (m-phase content: Ctrl – 0%; G – 12.3%; G LTD – 59.9%; Ctrl LTD – 81%). Surface topography and roughness analyses showed that grinding created an irregular surface (increased roughness) and aging did not promote any relevant surface change. There was no statistical difference on surface hardness among different conditions. The control group presented the lowest strength values in all tested rates. Regarding SCG, ground conditions were less susceptible to SCG, delaying its occurrence. Aging (LTD) caused an increase in SCG susceptibility for the as-sintered condition (i.e. G < G LTD < Ctrl < Ctrl LTD).

Abstract This in vitro study evaluated the fatigue strength of different ceramic materials indicated for monolithic restorations. Disc-shaped specimens were made according to ISO 6872 from five different ceramic materials: feldspathic ceramic (FC), polymer-infiltrated ceramic network (PIC), lithium disilicate glass-ceramic (LD), zirconia-reinforced lithium silicate glass-ceramic (ZLS), and high translucent tetragonal zirconia polycrystals doped by yttrium (YZ-HT). After obtaining the mean of each material (n = 5) from monotonic load-to-failure tests, specimens (n = 20) were subjected to fatigue tests (staircase method) using a biaxial flexural setup (piston-on-three-balls), to determine the fatigue strength. The parameters used for fatigue tests were: 100,000 cycles at 10 Hz, initial load of ~ 60% of mean load-to-failure, and step size of 5% of the initial load (specific for each ceramic material). Kruskal-Wallis and Bonferroni’s test (α = 0.05) were used to analyze the fatigue strength data. Fatigue strength (MPa) of the materials was statistically different among each other as follows: YZ-HT (370.2 ± 38.7) > LD (175.2 ± 7.5) > ZLS (152.1 ± 7.5) > PIC (81.8 ± 3.9) > FC (50.8 ± 1.9). Thus, it can be concluded that, in terms of fatigue, high translucent polycrystalline zirconia is the best choice for monolithic restorations as it bears the highest load before cracking/fracturing.

Abstract The present study investigated the effect of grinding on roughness, flexural strength, and reliability of a zirconia ceramic before and after heat treatment. Seven groups were tested (n = 15): a control group (labeled CG, untreated), and six groups of samples ground with diamond discs, simulating diamond burs, with grits of 200 µm (G80); 160 µm (G120), and 25 µm (G600), either untreated or heat-treated at 1200°C for 2 h (labeled A). Yttria tetragonal zirconia polycrystal discs were manufactured, ground, and submitted to roughness and crystalline phase analyses before the biaxial flexural strength test. There was no correlation between roughness (Ra and Rz) and flexural strength. The reliability of the materials was not affected by grinding or heat treatment, but the characteristic strength was higher after abrasion with diamond discs, irrespective of grit size. The X-ray diffraction data showed that grinding leads to a higher monoclinic (m) phase content, whereas heat treatment produces reverse transformation, leading to a fraction of m-phase in ground samples similar to that observed in the control group. However, after heat treatment, only the G80A samples presented strength similar to that of the control group, while the other groups showed higher strength values. When zirconia pieces must be adjusted for clinical use, a smoother surface can be obtained by employing finer-grit diamond burs. Moreover, when the amount of monoclinic phase is related to the degradation of zirconia, the laboratory heat treatment of ground pieces is indicated for the reverse transformation of zirconia crystals.