Fluoride concentrations in fissure and cervical enamel of unerupted human teeth

Fluoride concentration of fissure enamel from unerupted third molars was higher than that of the cervical-lingual but not cervical-buccal surfaces at a similar depth of the removed enamel. The highest fluoride concentration was found in the fissure enamel due probably to its earlier formation, higher permeability and embedding tissue before eruption.     

Fluoride acquisition on and in fluorotic human enamel after topical application in vitro

The uptake of alkali soluble and alkali insoluble fluoride on and in fluorotic enamel was investigated in vitro. Teeth from Kenya, assigned score 3 in accordance with Thylstrup-Fejerskov's fluorosis index, were used. The enamel was treated with either a neutral 2% NaF solution, a 0.2% NaF solution (pH 5.5), or the supernatant from a 0.1% NaF-containing toothpaste (pH 7). The treatment time was 1 h. The reaction product formed on the enamel was analyzed by KOH extraction and acid etching. Significantly higher amounts of alkali soluble fluoride were formed on the enamel from the 2% and 0.2% NaF solutions, as compared with the control. There was also a significant increase in the firmly bound fluoride after treatment with the neutral 2% NaF solution.     

Fluoride uptake from restorative dental materials by human enamel.

The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19F (p,alpha gamma) 16 O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts/10(6). All materials, except the composite, increased clearly the fluoride content of the underlyaing enamal. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel.     

Trace element concentrations in human enamel

Ninety-three samples of sound whole enamel derived from first premolars of individuals less than 20 yr of age were analysed by optical emission and atomic absorption spectroscopy for 21 trace elements. The teeth originated from 26 communities (11 States) of the U.S.A., representing many types of geographic environment and caries prevalence rates. The minimum, median, mean and maximum concentrations for the 21 elements are reported as baseline data for future reference.     

Electron microscopy of surface enamel of human unerupted and erupted teeth

The ultrastructure of the surface regions were studied using specimens ion-beam thinned from one side only. The crystalline surface of unerupted teeth was composed primarily of small (≈ 10 nm) loosely packed crystals and was overlaid by a primary cuticle which penetrated depressions in the underlying fine crystal layer. Some big (≈ 500 nm) crystals, 50 per cent of which were hydroxyapatite, were found among the small crystals and in the cuticle. The evidence suggested that, following eruption, this primary cuticle and the surface crystalline layer are removed and the coarser sub-surface crystalline layer is exposed to form the new surface typical of erupted teeth.     

Two types of intraoral distribution of fluorotic enamel

Abstract Different distributions of fluorotic dental enamel within the dentition have been described in the literature. This report describes two patterns of intraoral distribution. In nine Tanzanian low fluorosis communities with a prevalence of pitting fluorosis of less than 2% and in live moderate fluorosis communities with a prevalence of pitting fluorosis of 16–59%, incisors and first molars were the least affected teeth. In four high fluorosis communities with a prevalence of pitting fluorosis of 86–97%, maxillary incisors exhibited lower Thylstrup-Fejerskov Index values than the maxillary canines, premolars and molars. The mandibular teeth exhibited increasing Thylstrup-Fejerskov Index values from the anterior to the posterior region. The curves presenting the intraoral distribution of the severity of dental fluorosis corresponded with the curve presenting the completion time of primary enamel formation of the various tooth types, with the exception of the first molars in high fluorosis communities. The similarity of the curves suggests that the later in life enamel is completed, the higher is the severity of dental fluorosis. This relation seems to be explained by the prevailing feeding and dietary habits, which result in minimal intake of fluoride in the first 18 months of life during breastfeeding, followed by increasing fluoride ingestion in the following years through consumption of tea, seafish and F-containing magadi salt.     

Fluoride concentrations in the surface tooth enamel of young men and women

Comparisons were made between the F concentrations of enamel biopsies from the maxillary right central incisor of males and females in six locations with varying water F content. From 200 to 300 lifelong residents (mean age 13.5 yr) participated in each area. The mean F concentration of biopsies taken to comparable depths was generally about 10 per cent higher in males than in females. Analyses of biopsy data for the maxillary canine and lateral incisor in subgroups of 90–100 subjects showed a similar trend. The observed differences in F concentration appear to be related mainly to the longer pre-eruptive maturation time of the enamel in boys than in girls.     

Scanning electron microscopic study of fluorotic permanent teeth enamel

The materia comprised 8 caries-free fluorotic permanent teeth (4 with severe and 4 with very mild fluorosis) and 4 caries-free non-fluorotic permanent teeth. The surface of teeth with severe fluorosis was mainly rought with discrete pitting and small parts of relative sound enamel. The subsurface enamel of teeth with severe fluorosis was with irregular cross-sectional shape of rod and more extensive inter-rod enamel spaces in comparison with other parts of enamel. The surface enamel of teeth with very mild fluorosis was mainly smooth, similar to the sound enamel, with small parts of rough enamel. In subsurface enamel of teeth with very mild fluorosis no difference was found between cross-sectional shape of rod and dimension of inter-rod enamel spaces in comparison with other parts of enamel.     

Fluoride deposition in human enamel in vivo from professionally applied fluoride prophylaxis paste.

Deciduous teeth were collected from children who received professional prophylaxis with an acidulated phosphate-fluoride (APF) or placebo paste and were analyzed to determine fluoride uptake. Enamel fluoride level was increased by the APF paste approximately 300 ppm at a depth of 2.5 micrometers during the first month after the prophylaxis was administered, after which it returned to pretreatment levels.     

Fluoride uptake from restorative dental materials by human enamel

abstract – The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth ename1 and whether prior etching of the ename1 causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the ¹⁹F (p, αy) ¹⁶O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior ename1 was 226 parts/10⁶. All materials, except the composite, increased clearly the fluoride content of the underlying enamel. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel.     

Esthetic improvement following enamel microabrasion on fluorotic teeth: a case report.

Enamel microabrasion is a proven method of removing intrinsic and superficial defects from teeth, establishing esthetics with minimal loss of dental enamel. This article reports one case in which two different microabrasion techniques were used to remove fluorotic stains from teeth.     

Fluoride and enamel solubility

abstract — The present paper deals with the solubility of enamel and the influence of fluoride on the degree of saturation with respect to hydroxyapatite. Enamel surfaces were exposed to 8 ml buffer at various pH values. The buffers were analyzed at suitable intervals for calcium, phosphate, fluoride and pH and the ionic activity products for fluorapatite, hydroxyapatite, calcium fluoride, brushite and octacalcium phosphate were calculated. It was found that the buffers were supersaturated with respect to fluorapatite and remained unsaturated with respect to the other salts investigated. Under these conditions fluorapatite was formed while hydroxyapatite dissolved, the system thus tending toward equilibrium at which the liquid phase is saturated concurrently with respect to both apatites. It is suggested that at least a part of the solubility reducing effect of fluoride is due to fluoride rendering the liquid phase supersaturated with respect to fluorapatite. This results in formation of fluorapatite, rendering the liquid phase unsaturated with respect to hydroxyapatite.