Effects of postcuring and water sorption on the mechanical properties of composite dental restorative materials

Four commercial dental restorative composites with different filler contents, were tested for the effects of postcuring and water sorption on elastic modulus, compressive strength and ultimate strain. Large variations in mechanical properties were seen; water sorption plasticizes the matrix, causing loss of low molecular weight substances.

Peripheral blood flow in the neonate; 1. Changes in total, skin, and muscle blood flow with gestational and postnatal age

Total peripheral blood flow and blood flow through the skin and muscle were measured in the calf with an electrocapacitance plethysmograph with counter pressure in a group of 62 "well" newborn infants (birth weight, less than 3500 g). Blood pressure in the contralateral leg was measured with an Arteriosonde 1010, and peripheral vascular resistance was calculated as mean blood pressure (mm Hg) divided by blood flow (ml per 100 ml tissue per min). The results show that total peripheral blood flow and blood flow through he skin and muscle correlated inversely with increasing birth weight and gestational age. Postnatally, total blood flow and blood flow through the skin and muscle decreased gradually during the first 7 days of life and in the rest of the neonatal period. Peripheral vascular resistance and resistance in the skin and muscle correlated directly with increasing birth weight and gestational age. Postnatally, peripheral vascular resistance and resistance in the skin and muscle increased during the first 7 days of life and the neonatal period.

Current patterns of neonatal morbidity and mortality in infants of diabetic mothers

Recent advances in antepartum fetal evaluation have contributed to a marked reduction in fetal deaths in pregnancies complicated by overt diabetes mellitus. To determine the effect of these changes on neonatal morbidity and mortality, a retrospective analysis of complications in 322 infants of diabetic mothers (IDM) in White classes B--R was undertaken. The majority (89 per cent) of the IDM were delivered at term with a mean gestational age of 38 weeks. Neonatal morbidity correlated significantly with gestational age, occurring in 80 per cent of the preterm and 40 per cent of the term infants. The overall incidence of complications was: hyperbilirubinemia 37 per cent, hypoglycemia 31 per cent, hypocalcemia 13 per cent, polycythemia 8 per cent, and necrotizing enterocolitis 2 per cent. Respiratory distress syndrome (RDS) occurred in 9 per cent and congenital malformations in 6 per cent of the infants. Nine infants died, and four of these deaths were due to anomalies. These data indicate that (1) a reduction in fetal mortality has been accompanied by a reduction in neonatal mortality; (2) neonatal morbidity has been decreased but remains significant in the IDM; and (3) congenital anomalies have replaced RDS as a major cause of neonatal death for the IDM.