Characterization of Conventional and High-Translucency Y-TZP Dental Ceramics Submitted to Air Abrasion

Abstract This study evaluated the effect of air-abrasion on t®m phase transformation, roughness, topography and the elemental composition of three Y-TZP (Yttria-stabilized tetragonal zirconia polycrystal) dental ceramics: two conventional (Lava Frame and IPS ZirCad) and one with high-translucency (Lava Plus). Plates obtained from sintered blocks of each ceramic were divided into four groups: AS (as-sintered); 30 (air-abrasion with 30 mm Si-coated Al2O3 particles); 50 (air-abrasion with 50 mm Al2O3 particles) and 150 (air-abrasion with 150 mm Al2O3 particles). After the treatments, the plates were submitted to X-ray diffractometry; 3-D profilometry and SEM/EDS. The AS surfaces were composed of Zr and t phases. All treatments produced t®m phase transformation in the ceramics. The diameter of air-abrasion particles influenced the roughness (150>50>30>AS) and the topography. SEM analysis showed that the three treatments produced groove-shaped microretentions on the ceramic surfaces, which increased with the diameter of air-abrasion particles. EDS showed a decrease in Zr content along with the emergence of O and Al elements after air-abrasion. Presence of Si was also detected on the plates air-abraded with 30 mm Si-coated Al2O3 particles. It was concluded that irrespective of the type and diameter of the particles, air-abrasion produced t®m phase transformation, increased the roughness and changed the elemental composition of the three Y-TZP dental ceramics. Lava Plus also behaved similarly to the conventional Y-TZP ceramics, indicating that this high translucency ceramic could be more suitable to build monolithic ceramic restorations in the aesthetic restorative dentistry field.

Resumo Este estudo avaliou o efeito da abrasão a ar na transformação de fase t®m, na rugosidade, topografia e composição elementar de três cerâmicas Y-TZP (Zircônia tetragonal policristalina estabilizada por ítrio): duas convencionais (Lava Frame e ZirCad) e uma de alta translucidez (Lava Plus). Placas obtidas de blocos sinterizados de cada cerâmica foram divididos em quatro grupos: AS (pré-sinterizado); 30 (jateamento com partículas de Al2O3 de 30 mm cobertas com Si); 50 (jateamento com partículas de Al2O3 de 50 mm) e 150 (jateamento com partículas de Al2O3 de 150 mm). Após os tratamentos, as placas foram submetidas à difratometria de Rx, perfilometria 3-D e microscopia eletrônica de varredura com espectroscopia de energia dispersiva de Rx (SEM/EDS). As superfícies pré-sinterizadas apresentaram predominantemente Zr e fase tetragonal. Todos os tratamentos superficiais produziram transformação t®m nas cerâmicas avaliadas. A topografia e a rugosidade foram influenciadas pelo diâmetro das partículas abrasivas (150>50>30>AS). A análise através de SEM mostrou que os três tratamentos produziram fendas retentivas nas superfícies das cerâmicas, por influência do tamanho das partículas. A análise através de EDS mostrou uma diminuição da concentração de Zr, paralela ao surgimento de O e Al, após o jateamento. No grupo tratado com partículas de Al2O3 de 30 mm cobertas com Si foi também observado um aumento de Si após o jateamento. Concluiu-se que, independente do tipo e do diâmetro das partículas, o jateamento produziu transformação t®m, aumentou a rugosidade e alterou a composição elementar das cerâmicas avaliadas. A Lava Plus apresentou comportamento semelhante às cerâmicas convencionais, indicando que esta cerâmica de alta translucidez pode ser mais adequada à confecção de restaurações monolíticas no campo da odontologia estética restauradora.

Evaluación de citrato de calcio y magnesio obtenido de dolomitas cubanas / Evaluation of calcium and magnesium citrate from Cuban dolomite

INTRODUCTION: calcium and magnesium salts are used as nutritional supplements obtained from natural sources such as dolomite, which is a double complex of calcium and magnesium carbonate. In search of a calcium raw material with greater bioavailability, a process of obtaining calcium and magnesium citrate salt from dolomite deposits was developed. OBJECTIVE: to evaluate calcium and magnesium citrate from dolomite. METHODS: chemical and technological analysis, Powder X-ray Diffractometry attenuated total reflection-Fourier transform infrared spectrometry (ATR-FTIR), differential scanning calorimetry and thermogravimetric analysis were all used. RESULTS: the chemical analysis confirmed the existence of calcium (over 10 percent), and of magnesium (4.5 and 5 percent) whereas citric acid content was under 3 percent, The levels of toxic metals were below the maximum allowable limits for pharmaceutical products. The density values were below those of the dolomite, with high porosity and flow deficit. The X-ray diffractomery indicated that dolomite was transformed into calcium and magnesium citrate salts whereas, the infrared spectra showed the presence of characteristic COO¯, -OH and -CH2 groups of citrates. The differential scanning calorimetry showed that salt had three endothermic peaks at 101.7 ºC, 167.1 ºC y 194.6 ºC and on the other hand, termogravimetry analysis confirmed that 30.9 percent of the total mass is lost at temperatures lower than 295 ºC..CONCLUSIONS: the presence of calcium and magnesium citrate salt is corroborated(AU)

INTRODUCCIÓN: las sales de calcio y magnesio son utilizadas como suplementos nutricionales y se obtienen a partir de fuentes naturales, dentro de las cuales se encuentra la dolomita, que es un complejo doble de carbonato de calcio y magnesio. En la búsqueda de una materia prima de calcio con mayor biodisponibilidad, ha sido desarrollado un proceso de obtención de sales de citrato de calcio y magnesio a partir de dolomitas. OBJETIVO: evaluar el citrato de calcio y magnesio obtenido a partir de dolomita. MÉTODOS: se emplearon métodos de análisis químicos y tecnológicos, difracción de rayos X, reflexión total atenuada en el infrarrojo medio con transformada de Fourier, calorimetría diferencial de barrido y análisis termogravimétrico. RESULTADOS: los resultados del análisis químico demostraron la presencia de calcio (superior al 10 por ciento) y magnesio (entre 4,5 y 5 por ciento), mientras que el contenido de ácido cítrico fue menor al 3 por ciento. Los niveles de metales tóxicos estaban por debajo de los límites máximos permisibles para productos farmacéuticos. Los valores de densidades fueron inferiores a las densidades de la dolomita, con la presencia de un elevado porcentaje de porosidad y deficiente flujo. El análisis por difracción de rayos X demostró que la dolomita fue transformada en sales de citrato de calcio y magnesio, mientras que los espectros infrarrojos mostraron que las principales absorciones se corresponden con las de los grupos COO¯, -OH y -CH2, características todas de citratos. Los estudios por calorimetría diferencial de barrido indicaron que la sal presentaba tres transiciones endotérmicas a 101,7 ºC, 167,1 ºC y 194,6 ºC, y el análisis termogravimétrico corroboró que a temperaturas menores de 295 ºC ocurre una pérdida de masa que representa el 30,9 por ciento de la masa total. CONCLUSIONES: se corrobora la presencia de sal de citrato de calcio y magnesio(AU)

Ingredients and cytotoxicity of MTA and 3 kinds of Portland cements / 대한치과보존학회지

The aim of this study was to compare the compositions and cytotoxicity of white ProRoot MTA (white mineral trioxide aggregate) and 3 kinds of Portland cements. The elements, simple oxides and phase compositions of white MTA (WMTA), gray Portland cement (GPC), white Portland cement (WPC) and fast setting cement (FSC) were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD). Agar diffusion test was carried out to evaluate the cytotoxicity of WMTA and 3 kinds of Portland cements. The results showed that WMTA and WPC contained far less magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn) than GPC and FSC. FSC contained far more aluminum oxide (Al2O3) than WMTA, GPC, and WPC. WMTA, GPC, WPC and FSC were composed of main phases, such as tricalcicium silicate (3CaO.SiO2), dicalcium silicate (2CaO.SiO2), tricalcium aluminate (3CaO.Al2O3), and tetracalcium aluminoferrite (4CaO.Al2O3.Fe2O3). The significance of the differences in cellular response between WMTA, GPC, WPC and FSC was statistically analyzed by Kruskal-Wallis Exact test with Bonferroni's correction. The result showed no statistically significant difference (p > 0.05). WMTA, GPC, WPC and FSC showed similar compositions. However there were notable differences in the content of minor elements, such as aluminum (Al), magnesium, iron, manganese, and zinc. These differences might influence the physical properties of cements.

Quality standard for Baijiangdan / 中成药

AIM: Baijiangdan is a mineral herb containing mercuric chloride and mercurous chloride.To establish the quality standard for this mineral herb. METHODS: The microscope examination techniques,titration methods and X-ray diffractometry methods were used. RESULTS: These methods can be used for (identification) and quantitative (analysis) of Baijiangdan. CONCLUSION: This paper proposes microscopic examination techniques and physio-chemical methods such as X-ray diffractometry and titration methods for the identification and quantitative analysis of the herb.