ABSTRACT
ABSTRACT:Objective To observe the structural changes of dentin irradiated with Nd:YAG laser under dif-ferent parameters and the changes of calcium-phosphorus ration,and evaluate the optimal parameters of Nd:YAG laser in treating dentin hypersensitivity (DH).Methods The model of dentin hypersensitivity was established by acid etching method.Samples were irradiated with Nd:YAG laser under different parameters.The morphological alterations of the dentin surfaces and Ca-P ratio were examined with scanning electron microscopy (SEM)combined with energy dispersive X-ray microanalysis.Results Compared with those in the control group,dentinal tubules could be blocked partially or totally with no cracks in A-C (30 mj,5 Hz),(30 mj,10 Hz)and (50 mj,5 Hz)groups. Dentinal tubules could be entirely blocked but with cracks in D (50 mj,10 Hz)and E (80 mj,5 Hz)groups.Dentin was carbonized in F (80 mj,10 Hz)group.Compared with that in the control group,Ca-P ratio was decreased sig-nificantly (P <0.05).Conclusion The suitable energy parameter of Nd:YAG laser in treating dentin hypersensi-tivity is (30 mj,10 Hz)and (50 mj,5 Hz).
ABSTRACT
This study was carried out to evaluate the calcium and phosphorus intakes and correlation with growth performance of 25male breast and formula-fed infants from 1 to 3 months postpartum. There were four groups breast-fed(BF) and three formula-fed groups(FFM, FFN and FFP). There was no significant difference in the height and weight of infants according to feeding methods and formula brands. Milk intake and the concentration of calcium and phosphorus from human milk and the formulas were measured. The average calcium content of human milk was 26.6+/-4.1mg/dl and 13.5+/-2.0mg/dl, respectively. The average calcium intakes of the brest-fed and formula-fed infants were 205.5+/-29.3mg/day and the 460.5+/-70.6mg/day, respectively the average calcium intake of breast-fed infants was significantly lower than that of formula fed infant. The percent of RDA(41%) of breast-fed infants was lower than that(75.4%) of formula fed infant. The average phosphorus intake of the brest-fed and formula-fed infants were 105.1+/-20.1mg/day and 288.3+/-37.3mg/day, respectively. The precent of RDA(27%) for brest fed was significantly lower than that(75.4%) of formula fed. The Ca/P ratios were 2.1 in brest fed and 1.6 in formula fed infant. The average calcium and phosphorus intakes of the formula fed infants was higher than that of the brest-fed infants. This data suggests the calcium and phosphorus intakes form human milk sufficiently support the growth of infants. Therefore, the level of calcium and phosphorus recommended dietary allowances for infants should be reduced.