Scheie AA, Arneberg P, Krogstad O: Effect of orthodontic treatment on prevalence of Streptococcus mutans in plaque and saliva. Scand J Dent Res 1984; 92: 211-7.Abstract -The effect of orthodontic treatment on the prevalence of Streptococcus mutans was investigated in 14 subjects. Insertion of appliances tended to give a transient decrease in S.mutans levels, in both plaque and saliva, possibly due to elimination of S.mutans reservoirs by the banding procedure. After 3 months of extensive banding, the S.mutans proportions surpassed pretreatment levels in saliva and on banded teeth, whereas unbanded surfaces only showed a slight increase. It was thus concluded that creation of new retentive areas favors the local growth of S.mutans, which in turn increases the general infection level of this organism. Time was, however, needed before elevated levels were reached. Insertion of appliances tended to eliminate the characteristic gradient of S.mutans levels within the dental arches.

This work was based on the hypothesis that fingernail clippings can be used as a biomarker for the subchronic exposure to fluoride. The results provide data on factors that may affect the concentration of fluoride in fingernail clippings as determined with the electrode following HMDS–facilitated diffusion. The following variables had only minor or no effects on the concentrations: (1) the surface area of the clippings (intact, minced or filed into powder) that were placed into the diffusion dishes; (2) soaking in deionized water for up to 6 h; (3) soaking in fluoridated water (1.0 ppm) for 2 h, and (4) removal of the organic material of nails by dry ashing. Fingernail fluoride concentrations were approximately 50% higher than those in toenails. A 1–month period of increased fluoride intake by one of the authors resulted in significant increases in fingernail fluoride concentrations after a lag time of approximately 3.5 months. The fluoride concentrations in fingernail clippings obtained from three groups of Brazilian children were directly related to the concentrations in the drinking water (0.1, 1.6 or 2.3 ppm). The results indicate that: (1) HMDS–facilitated diffusion completely separates fluoride from intact nail clippings, so the need for ashing or other preparative methods is obviated; (2) fingernail fluoride is derived mainly from the systemic circulation, and (3) fluoride intake is reflected by the concentrations in fingernails.

On the basis of existing literature, efficient oral hygiene was found to have a caries preventive effect. The quality of the cleaning appears to be more important than the frequency of its performance. Professional tooth cleaning at regular intervals may inhibit caries on all tooth surfaces. The effect of self-performed oral hygiene has been demonstrated mainly on free smooth surfaces and on front teeth.