Calcium hydroxyapatite nanoparticles as a reinforcement filler in dental resin nanocomposite.

The current study focuses on the fabrication of calcium hydroxyapatite (Ca10(PO4)6(OH)2) (HA) in a nanorange having whiskers- and cubic-shaped uniform particle morphology. The synthesized HA particles hold a promising feature as reinforcement fillers in dental acrylic resin composite. They increase the efficacy of reinforcement by length and aspect ratio, uniformity, and monodispersity. Therefore, the acrylic resin was reinforced with the as-synthesized monodispersed HA filler particles (0.2-1 Wt%). The presence of filler particles in the composite had a noticeable effect on the tribological and mechanical properties of the dental material. The morphological effect of HA particles on these properties was also investigated, revealing that cubic-shaped particles showed better results than whiskers. The as-fabricated composite (0.4 Wt%) of the cubic-shaped filler particles showed maximum hardness and improved antiwear/antifriction properties. Particle loading played its part in determining the optimum condition, whereas particle size also influenced the reinforcement efficiency. The current study revealed that particle morphology, particle size, uniformity, etc., of HA fillers, greatly influenced the tribological and mechanical properties of the acrylic resin-based nanocomposite. Improvement in the tribological properties of HA particle-reinforced acrylic resin composites (HA-acrylic resin) followed the trend as AR < CmC < WC < CC.

Chemical modulation of crystalline state of calcium oxalate with nickel ions.

BACKGROUND: We explored that the presence of nickel ions in the precipitation medium affected size, shape and crystalline phase of the precipitated particles of calcium oxalate, whereas the applied synthesis conditions strongly influenced their uniformity. METHODS: Aqueous solutions of oxalic acid and calcium chloride, containing varying amounts of nickel sulfate, were mixed at room temperature and allowed to sonicate for various periods of time. The obtained particles were characterized by SEM, XRD, TG/DTA, and FTIR. RESULTS: Results revealed that particle morphology of calcium oxalate and their hydration states were dependent upon the chemical composition of the reactant solutions. For instance, the particles precipitated out in the form of dihydrate and having prismatic, and discs shaped particle morphology, when nickel ions were introduced in the starting reactant solution in different amounts. In contrast, the calcium oxalate particles precipitated under identical conditions in the absence of nickel ions were in the form of flakes with corrugated edges. Obvious variations were also found in the XRD patterns and crystallite size of these three solids. Heat treatment produced changes in the surface morphology of these particles due to loss of material and converted them calcium oxide. CONCLUSIONS: Gentle mixing of aqueous solutions of calcium chloride and oxalic acid in the absence and presence of nickel ions produced precipitated particles of calcium oxalate. Chemical composition of the reactant solutions and their order of mixing were found to be the key parameters in controlling the particle morphology and their hydration/crystalline state. Heat treatment at the elevated temperature transformed the as-prepared calcium oxalate to calcium oxide with visible changes in surface features of the particles.

Low amniotic fluid index in high-risk pregnancy and poor apgar score at birth.

OBJECTIVE: To determine the accuracy of antepartum Amniotic Fluid Index (AFI) of < or = 5 cm as a predictor of adverse outcome at birth in high-risk pregnancies. STUDY DESIGN: Cross-sectional study. PLACE AND DURATION OF STUDY: Obstetrics and Gynaecology Unit I, Holy Family Hospital and Railway Teaching Hospital Complex, Rawalpindi, from February 2003 to January 2004. METHODOLOGY: One hundred pregnant women at term gestation were studied. Each high-risk woman at term with an AFI of < or = 5 cm admitted for delivery through emergency or outpatient department was labeled as predictor of poor outcome. The next high-risk pregnant woman at term with the same pregnancy complication but an AFI of > 5 cm was labeled as predictor of good outcome at birth. The subjects in both the groups were demographically matched and fulfilled the inclusion and exclusion criteria. The Apgar score was calculated at 5 minutes of birth. The newborns, with Apgar score < or = 6 at 5 minutes of birth were labeled as diseased and > 6 were labeled as healthy. AFI was compared with Apgar score, using Chi-square and a p-value was calculated to determine the statistical significance. Sensitivity, specificity, efficiency and the predictive values of AFI at a cut off point of < or = 5 cm as a predictor of adverse outcome at birth (Apgar score of < or =6 at 5 minutes of birth) in high-risk pregnancy were calculated. RESULTS: Only 8 neonates of 50 women with low AFI had low Apgar score. Similarly, 6 neonates of 50 women with normal AFI had poor Apgar score. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value and efficiency of AFI as test were 57.1%, 51.3%, 16%, 88% and 52% respectively. CONCLUSION: Low AFI is a poor predictor of adverse outcome for high-risk term patients. AFI is not a good screening test for high-risk pregnant women at term for birth of an infant with low Apgar score.

Menstrual irregularities with excessive blood loss: a clinico-pathological correlation.

OBJECTIVE: To evaluate various histo-pathological features in endometrial curettings of patients complaining of menstrual irregularities with excessive blood loss and correlating them with clinical presentations. METHODS: A total of 260 endometrial curettings were obtained by Dilatation and Curettage done at the Department of Gynecology and Obstetrics, Railway Hospital, Rawalpindi. All the preserved specimens were processed under standard conditions at the Pathology Department, Islamic International Medical College (IIMC). The sections were studied after staining with Haematoxylin and Eosin stain. RESULTS: The patients presented with menorrhagia in 51.9%, metrorrhagia in 35.4%, polymenorrhoea in 9.2% and polymenorrhagia in 3.5% cases. History of hormonal intake was observed in 0.66% patients. Menstrual disorders were most common in 41-50 years age group accounting for 48% cases. Pathology was diagnosed in 40% of endometrial biopsies. The endometrial lesions included endometrial hyperplasia (24.7%), chronic nonspecific endometritis (13%), endometrial polyp (1.2%), pill pattern endometrium (2.3%) atrophic endometrium (0.8%) menopausal pattern endometrium, squamous metaplasia, squamous cell carcinoma and chorioncarcinoma (0.4% each). CONCLUSION: The dilatation and curettage was found to be an appropriate approach with a good diagnostic yield. Fortunately frequency of endometrial malignancy appeared to be very low. Endometrial hyperplasia was the leading causes of excessive menstrual bleeding.