Cellular and biochemical mechanisms, risk factors and management of preterm birth: state of the art.

Preterm birth (PTB) is usually defined as a delivery before 37 completed weeks or 259 days of gestation. World Health Organization estimates a worldwide incidence of PTB of 9.6%. Infants born preterm are at higher risks than infants born at term for mortality, and acute and chronic morbidity. Major causes of PTB are the following: spontaneous preterm labor with intact membranes (50%), labor induction or caesarean delivery for maternal or fetal indications (30%), and preterm premature rupture of membranes or PPROM (20%). The aim of this review is to analyze this medical condition, focusing on cellular and biochemical mechanisms, maternal risk factors and role of inflammation and infections in preterm premature rupture of membranes (PPROM) and PTB. Moreover we will discuss about the proper therapeutic strategies for its management. Although different methods have been introduced to predict the advent of preterm labour in asymptomatic women, possibilities for real primary prevention are rare. An early estimation of potential risk factors is pivotal in the secondary prevention of PTB. Finally most efforts so far have been tertiary interventions. These measures have reduced perinatal morbidity and mortality. Advances in primary and secondary care will be needed to prevent prematurity-related illness in infants and children.

Oral administration of fluoride in pregnant women, and the relation between concentration in maternal plasma and in amniotic fluid.

The aim was to measure the ionic fluoride concentration in maternal plasma and in amniotic fluid after oral administration of different doses of sodium fluoride (NaF) to 121 pregnant women. They were divided into six groups, according to the dose administered; 0 for the control group and 0.25, 0.50, 0.75, 1.00 or 1.25 mg of F- for the others. The subjects were instructed to take the corresponding NaF dose both 24 and 3 h before amniocentesis. Amniotic fluid (5 ml) and venous blood (5 ml) were obtained from each subject. Ionic fluoride concentration was measured with an expanded-scale potentiometer and a selective fluoride electrode. The results showed that F- concentration in amniotic fluid and, presumably, in fetal circulation, was not significantly different in groups taking 0.25, 0.50, 0.75 or 1.00 mg/day of F-. The F- concentration in amniotic fluid of the 1.25 mg/day group was, however, significantly higher than in all the other groups.

[Structural differences shown in enamel of deciduous and permanent teeth]. / Differenze strutturali evidenziabili fra lo smalto degli elementi decidui e quello dei permanenti.

Enamel is the first dental tissue to be injured by acid substances deriving from the metabolism of dental plaque in the development of caries lesions. The aim of this paper is the evaluation of structural differences between enamel of deciduous and permanent teeth, particularly the different toughness and degree of mineralization.

[Relations between sodium fluoride sensitivity and cariogenic potential in Streptococcus mutans]. / Rapporti fra sensibilità al fluoruro di sodio e potenziale cariogeno in Streptococcus mutans.

Supragingival plaque samples of a group of 59 schoolchildren were taken. The samples were cultivated on a selective medium for Streptococcus mutans and the isolated wild strains were tested for resistance to sodium fluoride (NaF). The results show the existence of a positive statistic correlation between the degree of resistance to NaF caries experience, obtained by DMFS of the experimental group.

[Biological basis of fluoride resistance]. / Le basi biologiche della resistenza al fluoro.

The authors synthetically illustrate some fundamental concepts about the mechanisms through which the oral flora develops fluoride resistance and the main consequences of this phenomenon at a biochemical and microbiological level. They briefly discuss the most recent experimental contributes of the literature in this field.