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Statement of Problem: Fully stabilized monolithic zirconia (FSZ) has been developed as an alternative to zirconia veneered with porcelain. However, how sintering conditions might affect its microstructure and optical and mechanical properties is unclear., Purpose: The purpose of this in vitro study was to determine the effect of different sintering temperatures on the microstructure and optical and mechanical properties of FSZ., Material and Methods: Bar-shaped FSZ specimens were prepared and divided into 2 groups (n=15) according to final sintering temperatures (1450 °C and 1600 °C). The average reflectance, opacity, translucency parameter, and sum of light absorption-scattering values were obtained by using a spectrophotometer, and ΔE 00 was calculated. The 3-point bend test was performed in a universal testing machine. Scanning electron microscopy (SEM) was conducted for microstructure analysis. Crystalline phase quantification was obtained by X-ray diffraction (XRD). Data were analyzed by using D'Agostino-Pearson and Student t tests (α=.05)., Results: A significant difference was detected in the reflectance and sum of light absorption-scattering values between the 2 groups. The translucency parameter, opacity, and flexural strength showed no statistical differences. ΔE 00 was 0.98. XRD indicated cubic (47.41% for 1450 °C; 46.04% for 1600 °C) and tetragonal content (52.59% for 1450 °C; 53.96% for 1600 °C). No monoclinic content was found. SEM images showed more definite grain boundaries in the 1600-°C group. Mean grain size was 0.49 μm for the 1450-°C group and 1.99 μm for the 1600-°C group., Conclusions: Higher sintering temperatures increased the grain size but did not change the crystal phase concentration. A significant difference was found in the reflectance and sum of light absorption-scattering, but no differences were found among the translucency parameter, opacity, or flexural strength., (Copyright © 2019 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Rifaximin, an oral antimicrobial drug, is marketed as 200-mg tablets. The daily dose ranges from 600 mg (1 tablet 3 times a day) to 800 mg (2 tablets twice a day). It is used for a wide range of ages, from adults to children, since it is indicated for the treatment of hepatic encephalopathy, travelers' diarrhea, irritable bowel syndrome, Clostridium difficile, ulcerative colitis, and acute diarrhea. The success of pharmacotherapy will depend on correct fulfillment of drug administration; however, it becomes difficult when the tablets are large and the doses are frequent. Rifaximin belongs to class IV according to the Biopharmaceutic Classification System (BCS), meaning that it is both poorly soluble and poorly permeable. Thus, in this study, solubility of rifaximin was improved by its complexation to β-cyclodextrin by (i) phase solubility diagram, (ii) malaxation, and (iii) decreasing particle size by wet milling. Improved solubility provides lower doses and facilitates compliance with pharmacotherapy. The products formed were analyzed by spectrophotometry in the infrared region (FT-IR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Also, their solubility and microbiological activity were determined. The products obtained in all techniques were more soluble than the free drug; they presented higher thermal stability and antimicrobial potency was approximately 100% with all the formulations. It is important to highlight that the treatment failure not only affects the quality of life of the patients, but also contributes significantly to the economic burden of the health system. Therefore, these findings are extremely interesting, both from a technological and financial point of view.

Objectives: To evaluate the effect of hydrothermal aging (H), mechanical cycling (M), and the combination of hydrothermal plus mechanical cycling (H+M) on biaxial flexural strength (BFS) and microstructure of two monolithic zirconias, indicated for anterior (AMZ) or posterior restorations (PMZ) and a conventional zirconia (IZr)., Methods: Disc specimens of each material (n=12) were submitted to: i) H (8h in autoclave at 134°C); ii) M (10 6 cycles, at 40% of BFS); and iii) H+M. BFS was measured (ISO-6872) and Weibull modulus (m) and the characteristic strength (σ 0 ) were calculated. crystalline phase composition analyzed by XRD, and grain size measured by MEV analysis., Results: XRD analysis showed AMZ was not susceptible to monoclinic transformation in any treatment. Conventional zirconia (IZr) and PMZ had monoclinic transformation only after H and H+M. BFS of AMZ was lower than PMZ and IZr. Cubic phase was found in all conditions for AMZ and IZr, while it was identified in PMZ only after H and H+M. BFS of AMZ was affected by M and H+M. For IZr and PMZ the unique difference detected in BFS was in the comparison of H to M. H treatment induced lower Weibull modulus, but characteristic strength was compatible with the BFS results. AMZ grain size (μm 2 ) was 8.6 times larger than PMZ grains, and 13.6 times larger than IZr grains., Conclusions: AMZ showed the largest mean grain size, had the lowest BFS values, and was affected when mechanical cycling was involved. Monoclinic transformation was not found in any treatment for AMZ, but was found in IZr and PMZ when hydrothermal aging was used alone or when combined with mechanical cycling. PMZ showed similar behavior to the IZr. H induced to higher fracture probability., Clinical Significance: Translucent monolithic dental zirconia available on the market may behave differently under simulated oral aging. The relationship between composition and microstructure determines their properties presumably, and clinical performance., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This study evaluated microstructural and crystallographic phase changes after grinding (G) and regeneration firing/anneling (R) of Y-TZP ceramics. Thirty five bars (Lava TM and Ice Zirkon) were divided: Y-TZP pre-sintered, control (C), regeneration firing (R), dry grinding (DG), dry grinding+regeneration firing (DGR), wet grinding (WG) and wet grinding+regeneration firing (WGR). Grinding was conducted using a diamond bur and annealing at 1,000°C. The microstructure was analyzed by SEM and the crystalline phases by X-ray diffraction (XRD). XRD showed that pre-sintered specimens contained tetragonal and monoclinic phases, while groups C and R showed tetragonal, cubic and monoclinic phases. After grinding, the cubic phase was eliminated in all groups. Annealing (DGR and WGR) resulted in only tetragonal phase. SEM showed semi-circular cracks after grinding and homogenization of particles after annealing. After grinding, surfaces show tetragonal and monoclinic phases and R can be assumed to be necessary prior to porcelain layering when grinding is performed.

Statement of Problem: The changes that occur after brushing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) are unknown. These changes may favor the retention of microorganisms and chemisorption of water, impairing its longevity., Objective: The purpose of this in vitro study was to evaluate the effects of a whitening dentifrice on Y-TZP surfaces after simulating 10 years of brushing., Material and Methods: Seventy-two bar-shaped specimens (20×4×1.2 mm) were divided into 4 groups: storage in distilled water (SW, control), brushing with distilled water (BW), brushing with dentifrice (BD), and brushing with whitening dentifrice (BWD). Brushing was conducted using a linear brushing machine (878400 cycles, 0.98 N, soft toothbrush). The mean roughness (Ra) was analyzed with a profilometer and the superficial topography with scanning electron microscopy (SEM) at baseline and after treatment. Crystalline phases were characterized using x-ray diffraction. Baseline and posttreatment Ra were analyzed using the 1-way ANOVA and Tukey HSD multiple comparison test; the paired t test was used for intragroup comparison (all α=.05)., Results: The Ra (μm) means (before/after treatment) were SW 0.28/0.28; BW 0.32/0.31; BD 0.28/0.36; BWD 0.30/0.20. No statistically significant difference was found for Ra at baseline (P=.108) than for posttreatment results (P<.001); the BD group had higher Ra values when compared with baseline (P=.019); the BWD group had the lowest values (P<.001). The BD surfaces showed pronounced scratches and detachment of the surface, while BWD showed smoother surfaces; similar crystallographic results among groups were observed., Conclusions: Brushing Y-TZP with conventional dentifrice increased roughness, while brushing with whitening dentifrice reduced roughness. Neither dentifrice changed the crystallographic phases after brushing., (Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Most ceramic abutments are fabricated from yttria-stabilized tetragonal zirconia (Y-TZP). However, Y-TZP undergoes hydrothermal degradation, a process that is not well understood., Purpose: The purpose of this in vitro study was to assess the effects of artificial aging conditions on the fracture load, phase stability, and surface microstructure of a Y-TZP abutment., Material and Methods: Thirty-two prefabricated Y-TZP abutments were screwed and tightened down to external hexagon implants and divided into 4 groups (n = 8): C, control; MC, mechanical cycling (1×10(6) cycles; 10 Hz); AUT, autoclaving (134°C; 5 hours; 0.2 MPa); and TC, thermal cycling (10(4) cycles; 5°/55°C). A single-load-to-fracture test was performed at a crosshead speed of 0.5 mm/min to assess the assembly's resistance to fracture (ISO Norm 14801). X-ray diffraction (XRD) analysis was applied to observe and quantify the tetragonal-monoclinic (t-m) phase transformation. Representative abutments were examined with high-resolution scanning electron microscopy (SEM) to observe the surface characteristics of the abutments. Load-to-fracture test results (N) were compared by ANOVA and Tukey test (α=.05)., Results: XRD measurements revealed the monoclinic phase in some abutments after each aging condition. All the aging conditions reduced the fracture load significantly (P<.001). Mechanical cycling reduced the fracture load more than autoclaving (P=.034). No differences were found in the process of surface degradation among the groups; however, the SEM detected grinding-induced surface flaws and microcracks., Conclusions: The resistance to fracture and the phase stability of Y-TZP implant abutments were susceptible to hydrothermal and mechanical conditions. The surface microstructure of Y-TZP abutments did not change after aging conditions., (Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Rifaximin is a gut-selective oral antimicrobial that has no systemic adverse effects compared with placebo. It is used for the treatment of hepatic encephalopathy, traveler's diarrhea, irritable bowel syndrome, Clostridium difficile infection, ulcerative colitis, and acute diarrhea. The crystalline form present in rifaximin, α, has minimal systemic absorption compared to the amorphous form. The objective of this study was to obtain polymorphic forms of rifaximin using recrystallization processes. The forms were characterized and studied by thermal analysis, X-ray powder diffraction, scanning electron microscopy, and solubility testing. Six polymorphic forms of rifaximin, designated I-VI, were obtained by the crystallization process by evaporation of the solvent. Some polymorphic forms obtained in this work may not have the same excellent tolerability as the reference medicine; therefore, studies such as these are extremely important and point to the need for greater requirements by the regulatory agencies overseeing polymorph analysis of the raw materials used in the manufacture of medicines marketed globally. These analyses are not required in the majority of official compendia. Partnerships among industries, research centers, and universities would be a viable way to consolidate research in this area and contribute to improving the quality of solid drugs.

Finasteride (FNT) is a drug that inhibits human enzyme type II 5α-reductase that metabolizes testosterone into dihydrotestosterone. There are two enantiotropic polymorphs with known crystal structure: designated as forms I and II. Identification and control of these polymorphic forms in mixtures can be performed using X-ray powder diffraction (XRPD) data and Rietveld method (RM). As experimental conditions may limit the detection of minority phases in mixtures, it is interesting to show what are these limits for some usual and one high-resolution equipment. So, in this work, we discuss the parameters to find the limit of the detection in binary mixtures of forms I and II of FNT according to each experimental condition. The samples analyzed were binary mixtures prepared with anhydrous polymorphs of the drug FNT. These samples were measured in four diffractometers with different experimental condition. These equipments represent the main resolutions generally used for drug analysis by XRPD. For the development of this work, a batch of form I was obtained pure, and another batch with forms I and II was used to obtain pure form II by heat treatment. Depending on the experimental condition, the polymorphs could be detected in a proportion as low as 0.5 wt%. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3567-3575, 2014., (© 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.)

The present work shows that the heated carbamazepine (CBZ) powder form III can be described as purely triclinic form I or a mixture of triclinic form I and monoclinic form III, depending on the resolution of the X-ray diffraction equipment used. Visual identification of the minor phase is possible when high-resolution synchrotron light is used. Quantitative phase analyses of CBZ forms I and III, after thermal treatment, were performed by using both synchrotron and conventional copper rotating anode X-ray powder diffraction data and the Rietveld method. Also, the Rietveld method could be adequately applied to determine the phase percentage in the heated material, even when usual resolution data are acquired., (Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association)

The crystal structure determination of mebendazole form A, an anthelmintic drug, was performed for the first time by applying the DASH software program to synchrotron X-ray powder diffraction data, and supported by a satisfying Rietveld fit. This polymorph of mebendazole crystallizes in a triclinic (P1) space group, with unit-cell parameters a = 5.5044(2) A, b = 11.2872(2) A, c = 12.5276(5) A, alpha = 66.694(2) degrees, beta = 82.959(2) degrees, gamma = 78.443(2) degrees, V = 699.52(5) A(3), Z = 2, M = 295.293 g mol(-1), rho(calc) = 1.4021 g cm(-3), and rho(meas) = 1.3935(66) g cm(-3), which were obtained by means of the unit-cell formula weight and a picnometric measurement, respectively. The goodness-of-fit and R-factors were, respectively: chi(2) = 1.746, R(F)(2) = 1.69%, R(wp) = 5.72%, and R(p) = 4.37%. A weak nonclassical hydrogen bond involving the atoms N(3)-H(23)...O(11) may be responsible for the greater stability of the polymorphic form A of mebendazole due to the strongest electronegativity of nitrogen., (2009 Wiley-Liss, Inc. and the American Pharmacists Association)