PURPOSE: Heat of composite polymerization (HP) indicates setting efficacy and temperature increase of composite in clinical procedures. The purpose of this in vitro experimental study was to evaluate the effects of 5 temperatures on HP of two new composites. MATERIALS AND METHODS: From each material (Core Max II [CM] and King Dental [KD]), 5 groups of 5 specimens each were prepared and their total HPs (J/gr) were measured and recorded, at one of the constant temperatures 0degrees C, 15degrees C, 23degrees C, 37degrees C and 60degrees C (2 x 5 x 5 specimens) using a differential scanning calorimetry (DSC) analyzer. The data were analyzed using a two-way ANOVA, a Tukey's test, an independent-samples t-test, and a linear regression analysis (alpha=0.05). RESULTS: No polymerization reactions occurred at 0degrees C; then this temperature was excluded from statistical analyses. The mean HP of the remaining 20 KD specimens was 20.5 +/- 14.9 J/gr, while it was 40.7 +/- 12.9 J/gr for CM. The independent-samples t-test showed that there were significant differences between the HP of the two materials at the temperatures 15degrees C (P=.0001), 23degrees C (P=.0163), 37degrees C (P=.0039), and 60degrees C (P=.0106). Linear regression analysis showed statistically significant correlations between environment temperatures and HP of CM (R2=0.777). CONCLUSION: Using CM is advantageous over conventional composite because of its better polymerization capacity. However due to its high HP, further studies should assess its temperature increase in vivo. Preheating KD is recommended. Refrigerating composites can negatively affect their polymerization potential.
Calorimetry, Differential Scanning ; Composite Resins ; Dental Materials ; Differential Thermal Analysis ; Hot Temperature ; Linear Models ; Polymerization ; Polymers ; Refrigeration

AIMTo study the structure and crystal forms of chlorobenzylidine.

METHODSKarl Fischer titrimetry, FTIR, thermal analysis, single and powder X-ray diffraction were used for the studies of the structure of chlorobenzylidine and for the identification of two forms of chlorobenzylidine.

RESULTSChlorobenzylidine and its diastereoisomer have been studied in this article. They can be distinguished by their different melting points. Two crystal forms of chlorobenzylidine (form A and form B) have also been detected and studied. Form A was studied by single-crystal X-ray diffraction, it crystallized in the triclinic system, space group P1(-), with two formula units per cell, is monohydrate. Karl Fischer titrimetry, FTIR, thermal analysis and powder X-ray diffraction were used for identification of the two forms.

CONCLUSIONThe studies of structure and crystal forms of chlorobenzylidine are very useful for the clinical research and the selection of recrystallization process.

Benzylidene Compounds ; Crystallization ; Crystallography, X-Ray ; Differential Thermal Analysis ; Molecular Conformation ; Molecular Structure ; Polycyclic Compounds ; chemistry ; Stereoisomerism

Crystal structures of chemical drugs has been being investigated widely. But few attention has been paid to polymorphs-phenomena of active ingredients from Traditional Chinese Medicine(TCM). Taking anhydrous dehydroandrographolide and hydrousprim-O-glucosylcimifugin as example, differences between TCM reference substances (RSs) with different crystal structures were discussed by using microscopy, melting point determination, differential thermal analysis (DTA) and infrared (IR) methods. The results showed that different crystal structures could lead to change of melting points, thermal behaviors and IR spectrum. It's indicated that polymorphs may be considered if different physicochemical properties were obtained when applying TCM RS. Differences of chemical properties of active ingredients from TCM with different crystal structures need further investigation.
Crystallization ; Differential Thermal Analysis ; methods ; standards ; Drugs, Chinese Herbal ; chemistry ; standards ; Medicine, Chinese Traditional ; Molecular Structure ; Reference Standards ; Spectrophotometry, Infrared ; methods ; standards ; Transition Temperature

AIMTo prepare salcatonin dry powder inhalations (sCT-DPIs) A (mixture of mannitol and L-leucine) and B (mixture of manntiol and lactose) by spray-drying and then to study their main pharmaceutical properties.

METHODSDumping rate of sCT-DPIs capsules and deposited fraction of sCT at effective part were determined according to Chinese Pharmacopiea 2000. Particle morphology under different relative humidity (RH) was observed by scanning electronics microphotograph, particle size and its distribution were determined by Malvern Mastersizer and the transition of morphorous state for carriers before and after spray-drying was investigated by differential thermal analysis (DTA) and X-ray powder diffraction (XRPD).

RESULTSDumping rates of sCT-DPIs A and B capsules were both above 10% and deposited fraction of sCT at effective part was above 90% for both A and B, which were all in agreement with the standard of Chinese Pharmacopiea 2000. Powder particle of sCT-DPIs A was round and existed one by one after keeping one month under RH 0, 23% and 52%, but aggregation can be observed under RH 75%; many particles which were also round agglomerated in sCT-DPIs B even under zero RH; mean particle size of sCT-DPIs A was 1.67 microns, which was much smaller than that of sCT-DPIs B; In sCT-DPIs A particle with empty core which was lighter than the same size particle with concreted core was observed. It was shown by DTA that melted heat of L-leucine in sCT-DPIs composed of mannitol and L-leucine lowered much more than that of L-leucine exisited alone after spray-drying. It was confirmed by XRPD that diffraction intensity of carriers in sCT-DPIs decreased more than that of carriers before spray-drying.

CONCLUSIONRound particle can be made when mannitol was added to carriers and ultra low density carriers can be formed when L-leucine was added. It was suggested by SEM that DPIs should be kept under certain RH. Particle size and distribution of sCT-DPIs all accorded with demand of DPIs. Complex spray-drying carriers formed amorphous state easier than single carrier.

Administration, Inhalation ; Anti-Asthmatic Agents ; administration & dosage ; Calcitonin ; administration & dosage ; Differential Thermal Analysis ; Leucine ; Mannitol ; Microscopy, Electron, Scanning ; Particle Size ; Powders ; Technology, Pharmaceutical ; methods

OBJECTIVETo prepare an inclusion complex of daidzein and hydropropyl-beta-cyclodextrin to enhance the solubility of daidzein.

METHODThe inclusion complex of daidzein was prepared by the solution stirring method. The binary system of daidzein and HP-beta-CD was confirmed by differential thermal, thermogravimetry analysis, infrared spectroscopy and X-ray diffractometry.

RESULTThe drug content in the inclusion complex was 6. 76% and the solubility was 13.68 mg x mL(-1). The identification results showed that the inclusion complex was formed.

CONCLUSIONThe preparation method of the inclusion complex of daidzein and hydropropyl-beta-cyclodextrin is simple and available, with a increased solubility of daidzein.

2-Hydroxypropyl-beta-cyclodextrin ; Differential Thermal Analysis ; Drug Compounding ; methods ; Isoflavones ; chemistry ; Solubility ; Spectroscopy, Fourier Transform Infrared ; X-Ray Diffraction ; beta-Cyclodextrins ; chemistry

OBJECTIVETo study the characteristics of thermal expansion of the alumina-zirconia nano-composite infiltrated ceramic.

METHODSThe thermal expansion coefficients of alumina-zirconia composite matrix, infiltrating glass and infiltrated ceramic were determined by various methods, respectively.

RESULTSThe coefficients of thermal expansion of composite matrix with 10 wt%, 20 wt% and 30 wt% zirconia were 7.607, 7.690 and 8.111 microns/(m. degree C) respectively. The thermal expansion coefficients of AZ-8 and AZ-10 infiltration glass were 6.867 and 7.333 microns/(m. degree C), respectively. The thermal expansion coefficient of infiltrated ceramic was 8.413 microns/(m. degree C).

CONCLUSIONThe thermal expansion coefficients of the glass and composite matrix matched well. The thermal expansion coefficients of the alumina-zirconia nano-composite infiltrated ceramic and several common veneering porcelains matched well, too.

Aluminum Oxide ; chemistry ; Dental Materials ; chemistry ; Dental Porcelain ; chemistry ; Dental Stress Analysis ; Differential Thermal Analysis ; Hardness ; Hot Temperature ; Materials Testing ; Metal Ceramic Alloys ; chemistry ; Nanotechnology ; Stress, Mechanical ; Zirconium ; chemistry

The technique of liquisolid compress is a new technique developed in 1990s, which was considered to be the most promising technique to improve the dissolution of water-insoluble drugs. In this article, tanshinone II(A) and the extracts of the ester-solubility fractions were chosen as the model drugs to evaluate the effects of the liquisolid technique for enhancement of dissolution properties of tanshinone II(A). Several liquisolid tablets (LS) formulations containing different dosage of drugs and various liquid vehicle were pre-pared and for all the formulations, microcrystalline cellulose and silica were chosen as the carrier and coating materials to evaluate their flow properties, such as angle of repose, Carr's compressibility index and Hausner's ratio. The interaction between drug and excipients in prepared LS compacts were studied by differential scanning calorimetry(DSC) and X-ray powder diffraction (XRPD). The dissolution curves of tanshinone II(A) from liquisolid compacts were investigated to determine the technique's effect in improving the dissolution of tanshinone II(A) and its impacting factors. According to the results, the dissolution increased with the rise in the dissolution of the liquid-phase solvent. The R-value and drug dosage can significantly affect the drug release, but with less impact on active fractions. This indicated that liquisolid technique is a promising alternative for improvement of dissolution property of water-soluble drugs, and can make a synergistic effect with other ester-soluble constituents and bettern improve the release of tanshinone II(A). Therefore, the technique of liquisolid compress will have a better development prospect in traditional Chinese medicines.
Calorimetry, Differential Scanning ; Diterpenes, Abietane ; chemistry ; Solubility ; X-Ray Diffraction

STATEMENT OF PROBLEMS: The heat produced during polymerization of polymer-based provisional materials may cause thermal damage to the vital pulp. PURPOSE: This study was performed to evaluate the exotherm reaction of the polymerbased provisional materials during polymerization by differential scanning calorimetry and to compare the temperature changes of different types of resins. MATERIAL AND METHODS: Three dimethacrylate-based materials (Protemp 3 Garant, Luxatemp Plus, Luxatemp Fluorescence) and five monomethacrylate-based material (Snap, Alike, Unifast TRAD, Duralay, Jet) were selected. Temperature changes of polymer-based provisional materials during polymerization in this study were evaluated by D.S.C Q-1000 (TA Instrument, Wilmington, DE, USA). The following three measurements were determined from the temperature versus time plot: (1) peak temperature, (2) time to reach peak temperature, (3) heat capacity. The data were statistically analyzed using one-way ANOVA and multiple comparison Bonferroni test at the significance level of 0.05. RESULTS: The mean peak temperature was 39.5 degrees C (+/- 1.0). The peak temperature of the polymer-based provisional materials decreased in the following order: Duralay > Unifast TRAD, Alike > Jet > Luxatemp Plus, Protemp 3 Garant, Snap, Luxatemp Fluorescence. The mean time to reach peak temperature was 95.95 sec (+/- 64.0). The mean time to reach peak temperature of the polymer-based provisional materials decreased in the following order: Snap, Jet > Duralay > Alike > Unifast TRAD > Luxatemp Plus, Protemp 3 Garant, Luxatemp Fluorescence. The mean heat capacity was 287.2 J/g (+/- 107.68). The heat capacity of the polymer-based provisional materials decreased in the following order: Duralay > TRAD, Jet, Alike > Snap, Luxatemp Fluorescence, Protemp 3 Garant, Luxatemp Plus. CONCLUSION: The heat capacity of materials, determined by D.S.C., is a factor in determining the thermal insulating properties of restorative materials. The peak temperature of PMMA was significantly higher than others (PEMA, dimethacrylate). No significant differences were found among PEMA (Snap) and dimethacrylate (P > 0.05). The time to reach peak temperature was greatest with PEMA, followed by PMMA and dimethacrylate. The heat capacity of PMMA was significantly higher than others (PEMA, dimethacrylate). No significant differences were found among PEMA and dimethacrylate (P>0.05).
Calorimetry, Differential Scanning* ; Crowns* ; Denture, Partial, Fixed* ; Fluorescence ; Hot Temperature ; Polymerization ; Polymers ; Polymethyl Methacrylate

Baicalin extremely fine powder was made by using ball-mill and the effect of micronization on the micromeritics properties of baicalin was studied and analyzed. The microstructures of baicalin ordinary and extremely fine powder were compared by scanning electron microscope, differential scanning calorimeter and X-ray diffraction and the powder characteristic of them was investigated. The hygroscopicity was studied. The effect of micronization on the dissolution of baicalin was investigated. The results showed that the chemical constituents of baicalin were not changed after micronization with better compressibility. It was confirmed that micronization technology had a certain application value in promoting the insoluble component of baicalin absorption with higher dissolution.
Calorimetry, Differential Scanning ; Drugs, Chinese Herbal ; chemistry ; Flavonoids ; chemistry ; Particle Size ; Solubility ; Wettability ; X-Ray Diffraction

OBJECTIVETo enhance the dissolution rate of daidzein with solid dispersion technique.

METHODSolid dispersions were prepared by the solvent method using water-solubility chitosan as a hydrophilic carrier. DSC, IR and X-ray methods were used to verify the formation of solid dispersion.

RESULTDissolution percentages of solid dispersions were more than 90 percent in the drug-carrier ratio of 1:5 and 1:9. But dissolution percentages of physical mixtures and pure drug were 40 and 38.4 percent respectively. Part of daidzein dispersed in solid dispersion in the form of microcrystalline.

CONCLUSIONWater-soluble chitosan solid dispersion can significantly increase dissolution rate of daidzein.

Calorimetry, Differential Scanning ; Chitosan ; chemistry ; Isoflavones ; chemistry ; Solubility ; Spectrophotometry, Infrared ; Water ; chemistry ; X-Ray Diffraction