Does breastfeeding increase risk of early childhood caries?

According to the WHO, "breastfeeding is the normal way of providing young infants with the nutrients they need for healthy growth and development. Exclusive breastfeeding is recommended up to 6 months of age, with continued breastfeeding along with appropriate complementary foods up to two years of age or beyond". However, several studies have reported prolonged and unrestricted breastfeeding as a potential risk factor for primary tooth caries (ECC). On-demand breastfeeding, particularly while lying down at night, would seem to cause ECC because milk remains in the baby's mouth for long periods of time. There is lack of evidence that human milk is cariogenic; other factors, such as oral hygiene, may be more influential in caries development than on-demand breastfeeding. Moreover the biomechanics of breastfeeding differs from those of bottle feeding and milk is expressed into the soft palate and swallowed without remaining on teeth. Indeed we cannot forget that the main factor influencing caries development in infants is the presence of bacteria streptococcus mutans that thrives in a combination of sugars, small amounts of saliva and a low pH. Today the question is open and recently Chaffee, Felines, Vitolo et al. [2014] have found that breastfeeding for 24 months or longer increases the prevalence of severe early childhood caries in low-income families in Porto Alegre, Brazil. These results do not claim that prolonged breastfeeding is the cause of tooth decay; we can expect an association with food for infants often rich in refined sugars, which cause the reduction of the protective effect of saliva on the deciduous teeth enamel. In Japan, Kato, Yorifuji, Yamakawa et al. [2015] have found that infants who had been breastfed for at least 6 or 7 months, both exclusively and partially, were at elevated risk of dental caries at the age of 30 months compared with those who had been exclusively fed with formula. The authors themselves say, however, that further studies with more elaborate methods of assessment of breastfeeding may be necessary to determine the cariogenic nature of breastfeeding. In the meantime, given the many benefits of breastfeeding, the practice should continue to be strongly encouraged. Dental professionals should encourage parents to start proper oral hygiene with their children as soon as the first tooth erupts, and they should keep the intake of sugary beverages to a minimum.

Isolation and partial characterization of active polysomes from calcified and matrix-containing tissues.

Polysomes were isolated from calcified and matrix-containing tissues, such as rat calvaria, rat chondrosarcoma and chick embryos. The method of isolation involves preliminary swelling of the tissues in hypotonic buffer containing heparin and cycloheximide. After homogenization, differential centrifugation is used to separate membrane-bound and non-bound polysomes. Each fraction is rehomogenized in the presence of detergent (Triton X-100) and potassium ions (0.25M). Polysomes are harvested by centrifugation through sucrose cushions in the continued presence of high levels of potassium ions and heparin. Total, non-bound, and membrane-bound polysomes prepared in this manner are equally active in protein synthesizing activity in an heterologous cell-free system. The distribution between non-bound and membrane-bound polysomes in the 12 day old chick embryo is 43 and 57 per cent respectively. Sucrose gradient profiles of polypeptide chains on polysomes labeled in organ culture correlate well with the protein synthetic activity of the isolated polysomes. Much of the protein synthetic activity is devoted to collagen. Polysomal fractions obtained from sucrose gradients show preferential incorporation of 3H-proline and nearly 60 per cent of trichloroacetic acid precipitable material is susceptible to collagenase digestion. Products of synthesis are also substrates for collagen specific enzyme, prolyl hydroxylase. The method described in this communication overcomes the inherent difficulties in obtaining active polysomes from calcified and matrix-containing tissues.