The effect of thermocycling on the bonding of different restorative materials to access opening through porcelain fused to metal restorations

PURPOSE

Porcelain fused to metal (PFM) crowns provide the best treatment option for teeth that have a large or defective restoration. More than 20% of teeth with PFM crowns or bridges require non-surgical root canal treatment (NSRCT). This may be due to the effect of restorative procedures and the possible leakage of bacteria and or their by-products, which leads to the demise of the tooth pulp. Thus, this study was planned to compare the ability of the restorative materials to seal perforated PFM specimens.

MATERIALS AND METHODS

The study evaluates the ability of amalgam, composite or compomer restorative materials to close perforated PFM specimen''s in-vitro. Ninety PFM specimens were constructed using Ni-Cr alloys and feldspathic porcelain, and then they were divided into 3 groups: amalgam (A), composite + Exite adhesive bond (B) and compomer + Syntac adhesive bond (C). All the PFM samples were embedded in an acrylic block to provide complete sealing of the hole from the bottom side. After the aging period, each group was further divided into 3 equal subgroups according to the thermocycling period (one week for 70 cycles, one month for 300 cycles and three months for 900 cycles). Each subgroup was put into containers containing dye (Pelikan INK), one maintained at 5℃ and the other at 55℃, each cycle for 30 sec time. The data obtained was analyzed by SPSS, 2006 using one way ANOVA test and student t-test and significant difference level at (P<.01).

RESULTS

The depth of dye penetration was measured at the interfaces of PFM and filling materials using Co-ordinate Vernier Microscope. The lowest levels of the dye penetration for the three groups, as well as subgroups were during the first week. The values of dye leakage had significantly increased by time intervals in subgroups A and C.

CONCLUSION

It was seen that amalgam showed higher leakage than composite while compomer showed the lowest level of leakage.     

Validated gradient stability indicating HPLC method for determining Diltiazem Hydrochloride and related substances in bulk drug and novel tablet formulation

A stability-indicating liquid chromatographic method has been developed and validated for the determination of Diltiazem Hydrochloride (DTZ) together with its six related substances (Diltiazem sulphoxide, Imp-A, Imp-B, Imp-D, Imp-E, and Imp-F) in a laboratory mixture as well as in a novel tablet formulation developed in-house. Efficient chromatographic separation was achieved on a Hypersil BDS C₁₈ (150 mm×4.6 mm, 5.0 μm) with mobile phase containing 0.2% Triethylamine (TEA) in gradient combination with acetonitrile (ACN) at a flow rate of 1.0 mL/min and the eluent was monitored at 240 nm. In the developed method, the resolution of DTZ from any pair of impurities was found to be greater than 2.0. The test solution and related substances were found to be stable in the diluent for 24 h. The developed method resolved the drug from its known impurities, stated above, and also from additional impurities generated when the formulation was subjected to forced degradation; the mass balance was found close to 99.9%.Regression analyses indicate correlation coefficient value greater than 0.997 for DTZ and its six known impurities. The LOD for DTZ and the known impurities was at a level below 0.02%. The method has shown good, consistent recoveries for DTZ (99.8–101.2%) and also for its six known impurities (97.2–101.3%). The method was found to be accurate, precise, linear, specific, sensitive, rugged, robust, and stability-indicating.     

Bicameral rupture of aneurysm of sinus of valsalva

A rare case of bicameral rupture of aneurysm of noncoronary Sinus of Valsalva with severe aortic stenosis in an Indian female patient is reported. While closing the fistula from aorta, it is important to avoid any persistence of the fistula between the right atrium and ventricle beneath the patch.     

Perineal length: norms in gravid women in the first stage of labour

Introduction  

The purpose of this study was to generate normative data for perineal length for Caucasian and Asian women in labour.     

Development of Validated Bioanalytical HPLC-UV Method for Simultaneous Estimation of Amlodipine and Atorvastatin in Rat Plasma

A simple, economical and robust analytical high-performance liquid chromatography-ultraviolet method was developed and validated for simultaneous chromatographic elution of two cardiovascular drugs viz. amlodipine and atorvastatin in biological fluid for the first time. Only two liquid chromatography–mass spectrometry/mass spectrometry methods are available in literature for quantitation of selected pair of analytes. The bioanalytical method was developed in rat plasma by using Thermo beta-basic C₁₈ (100×4.6 mm, 5 μm) and mobile phase was composed of dibasic phosphate buffer (pH 3.0):acetonitrile in the ratio of 55:45 at a flow rate of 1 ml/min with ultraviolet detection monitored at 240 nm. The selected chromatographic conditions were found to effectively separate amlodipine (5.1 min) and atorvastatin (12.1 min). The parametric statistics,i.e. correlation coefficient of 0.999, was assessed for both the drugs having linearity over the tested concentration range (0.05 to 10.0 μg/ml) in rat plasma using an unweighted calibration curve. The mean recovery (%) was more than 92.8% for both the drugs using protein precipitation method. The accuracy of samples for six replicate measurements at lower limit of quantitation level was within limit. The method was validated and was successfully applied to the nonclinical pharmacokinetic study of combination tablets containing amlodipine and atorvastatin in six Sprague Dawley rats.