Salivary mutans streptococci and lactobacilli in 9- and 13-year-old Italian schoolchildren and the relation to oral health.

The prevalence and levels of mutans streptococci (MS) and lactobacilli (LB) in saliva and its possible correlation with dental caries and periodontal conditions was investigated in 473 Italian schoolchildren, 9 and 13 years of age. A clinical examination and sampling of stimulated whole saliva was carried out in the school and oral health was assessed as DMFT and CPITN using the WHO criteria. The saliva samples were frozen in liquid nitrogen and after thawing, cultivated on selective media. To test the influence of cryopreservation, fresh samples from 20 subjects were cultivated. Thirty-five percent of the children were caries-free with a mean DMFT of 1.9 at the age of 13. The majority exhibited healthy periodontal conditions. Salivary MS and LB were identified in 52% and 21% of the children, respectively. The prevalence of MS was higher among the 13-year-olds than the 9-year-olds while no such difference was found regarding LB. There was a statistically positive relationship (P < 0.01) between the levels of MS and LB and both were significantly correlated to caries (P < 0.01). The correlation coefficient of microbial recovery between frozen and unfrozen samples was 0.99. In conclusion, the data provided cross-sectional information of a clear positive relationship between selected micro-organisms in saliva and caries in 9- and 13-year-old children in spite of a relatively low prevalence of the disease. The findings are discussed in a risk selection perspective.

Caries-preventive effect of topical amine fluoride in children with high and low salivary levels of mutans streptococci.

The aim of the study was to assess the relationship between the salivary mutans streptococci (SMS) level and the effectiveness of a preventive intervention based on a biannual application of an amine fluoride solution (AmF). A total of 284 schoolchildren aged 6 years were recruited from eleven classes of a primary school in Milan and randomly assigned to an experimental (A) and a control group (B). SMS counts were obtained at baseline and caries incidence data (diseased, missing, filled teeth, DMFT) were recorded every 6 months for 5 years. The participants of the experimental group received application of an AmF 1% F(-) solution twice a year on the enamel surfaces of the first permanent molars for 5 years. Control group subjects received application of a placebo solution twice a year on the enamel surfaces of the first molars for the same period. The mean DMFT in the experimental and control groups were 0.56 and 0.22, respectively, at the beginning and 1.14 and 2.06 after 5 years. SMS data allowed children to be classified into low- (0-10(5) CFU/ml of saliva) and high- (>10(5) CFU/ml of saliva) SMS subjects. Survival analysis, performed on the first molar data split by SMS group, showed a significantly higher caries reduction in low-SMS experimental group subjects compared to low-SMS control group subjects after 5 years. No significant differences were found between the two high-SMS experimental and control groups. These findings indicate that the preventive effects of the treatment were significantly lower in subjects who had high SMS. It is concluded that the effectiveness of a simple and economical topical fluoride intervention applicable at a community level is significantly influenced by the SMS level of the subjects involved. Simple AmF preventive interventions, applied on low-SMS subjects, can give significant results in terms of caries reduction.

A simplified micromethod for fluoride analysis.

A simplified method for the determination ionic fluoride (F-) concentrations in microvolume samples using a F(-)-selective electrode is described. Portions (20 microl) of a series of F- standard solutions (1000-0.4 parts/10(9) F-) were placed between the surface of the F- electrode and the surface of a reference electrode mounted end to end with the aid of a steel holder. In this position the two surfaces were used as an analysis chamber, retaining the sample by surface tension without the use of sleeves or other devices. The precision of the results and the absolute detection limit of the modified method were determined. The analytical performance of this set-up was tested by comparing the results with those obtained from the conventional method. The regression between the modified-method data and the conventional-technique data showed a strong correlation (R2 = 0.993) between the results obtained using the two techniques. In the range of F- concentrations from 1000 and 0.48 parts/10(9), the precision of the results (coefficient of variation) was of 5-6%, improving to 0.9% at 0.9 parts/10(9) level.

Caries prevention during pregnancy: results of a 30-month study.

The purpose of this 30-month study was to explore the effectiveness of a caries-preventive regimen in lowering the salivary mutans streptococci level in pregnant women and, subsequently, in inhibiting the growth of these bacteria in their young children. Beginning at the end of the sixth month of pregnancy and continuing until delivery, subjects rinsed daily with 0.05 percent sodium fluoride and 0.12 percent chlorhexidine. The authors monitored the salivary mutans streptococci levels during the last six months of pregnancy and every six months thereafter for 24 months. They also measured bacterial levels in the children every six months until they reached age 24 months. The results show that treatment significantly reduced salivary mutans streptococci levels in mothers and delayed the colonization of bacteria in their children for about four months.

The effect of surface roughness on early in vivo plaque colonization on titanium.

THE STUDY ASSESSES IN VIVO the surface roughness necessary to reduce plaque colonization on titanium after 24 hours. Three groups of 16 titanium disks were assigned to 3 different polishing groups (A, B, and C). The roughness was evaluated with a laser profilometer and the morphology with a scanning electron microscope (SEM). Eight volunteers were enrolled and two stents were applied in the mandibular posterior region of each. Each stent supported 3 disks, one per group. The volunteers suspended oral hygiene for 24 hours, after which the stents were removed; one was processed for evaluation of the adherent biomass and the other for SEM study. On each specimen a global area of 100 x 125 microns was examined with SEM. The area was composed of five 20 x 25 microns randomly selected fields. For each field the density of bacteria and the morphotypes were recorded. The data quoted for the global area are cumulative of those observed in the 20 x 25 microns fields. Group A had a significantly smoother surface than groups B and C. The adherent microbial biomass determination and SEM evaluation revealed that group A contained less bacteria than the roughest group. The bacterial population was composed of cocci in group A, and of cocci and short and long rods in groups B and C. We conclude that a titanium surface with Ra < or = 0.088 microns and Rz < or = 1.027 microns strongly inhibits accumulation and maturation of plaque at the 24-hour time period and that such smoothness can be achieved in transgingival and healing implant components.

The effect of biannual applications of amine fluoride solution on caries incidence in permanent first molars: a 5-year study.

A randomized double-blind clinical trial was undertaken in a non-fluoridated community to assess the effectiveness of a minimal preventive intervention based on biannual applications of an amine fluoride (AmF) solution containing 1% fluoride. A total of 284 schoolchildren aged 6 years were recruited from a primary school in Milan, Italy, and randomly assigned to an experimental or a control group. The subjects of the experimental group received two applications each year of AmF to the permanent first molars and the control group subjects received similar applications of a placebo solution. Both in the experimental and control groups caries experience (DMFT) of the first molars was recorded every 6 months for 5 years. The mean DMFT scores in the experimental and control group were, respectively, 0.56 and 0.22 at the beginning and 1.14 and 1.75 at the end of the study. The preventive effect of the treatment became statistically significant only after 3 years. Survival analysis performed on the first molars that were sound at baseline showed that the topical AmF treatment caused, after 5 years, a significant reduction of caries incidence. This result confirms observations found in the international literature on the anticaries action of AmF. The administration rate used in this study seems to be useful for community preventive applications as it reduces the total amount of fluoride administered and the potential risks, and involves few personnel.