M.F. Little

Enamel Dissolution: II. Action of Titanium Tetrafluoride

Mechanisms by which titanium tetrafluoride (TiF4) reduces enamel solubility were investigated. An association was found between solubility reduction and the formation of a glaze on the enamel surface. Also, TiF4treated enamel had higher levels of fluoride than enamel treated with acidulated phosphate-sodium fluoride. Solubility reductions and fluoride levels decreased slightly with washing but after 48 hours the fluoride level was still 60% of the maximum, and solubility reductions ranged between 64 and 70%.

Chemical and physical properties of altered and sound enamel—IV: Trace element composition

Abstract The trace element composition of sound enamel was found to be the same in the outer and the inner enamel. A very slight increment in Zn, Pb, Cu, Sn and Al occurred in sound enamel of older teeth. Two to three times the Zn and Pb, Cu, Sn, and Al content was found in outer diffusely discoloured “sound” enamel from the same teeth. The fluoride content in this enamel was 10 times that of adjacent completely sound enamel. Pre-carious white and brown spots had a variable but high level of trace elements with Zn and Cu higher in the younger than the older teeth. Cobalt was found in neither the sound nor the precarious enamel.

X-ray diffraction analysis of human enamel containing different amounts of fluoride.

Abstract X-ray diffraction studies were conducted on a series of enamel samples from areas with different amounts of fluoride in the drinking water. There appears to be a relationship between the fluoride content of enamel and duration of exposure. The degree of association between fluoride and diffraction profile breadth was r = − 0.9 for the (002) set of planes. The (211), (300) and (202) also showed an inverse relationship. Size calculations relate the change which could be expected if strain is considered a negligible factor in broadening the diffraction profile.

The pH of carious cavities—I: The effect of glucose and phosphate buffer on cavity pH

Abstract The thickness of decayed material and the size of the clinical openings of cavities were correlated with the initial pH and the pH response to glucose and phosphate buffer. Using visual and X-ray measurements, cavities were classified into the following types: (I) small clinical openings and thick layers of decay, (II) wide clinical openings and thick layers of decay, and (III) wide clinical openings and thin layers of decay. The three types of cavities had different mean initial pH values and responded differently to a 10% glucose solution. The average pH value of all Type I cavities was lowest both initially and during the 30 min period after glucose. Type III cavities under similar conditions had the highest average pH value. After isolation, 0.1 M phosphate buffer (pH 6.8) was added to cavities and Type III cavities were found to reach a pH of 6.8 in a shorter length of time than Types I and II. Following removal of the phosphate buffer, Type III cavities reverted to their initial pH values in a shorter length of time than the other cavity types.

Trace element concentrations in human enamel.

Abstract 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.

The pH of carious cavities-II. The pH at different depths in isolated cavities.

Abstract Using a micro-antimony electrode, the pH of a number of cavities, classified into three types according to decay thickness and clinical opening size, was measured both before and after excavation, and isolation from the neutralizing effects of saliva. On excavation, the pH of the bottom layers in cavities, regardless of type, were always lower than the pH of the corresponding surface layers. The pH values of the top and bottom layers in cavities with small clinical openings and thick layers of decay, were lower than in cavities with thin layers and large clinical openings. In most instances, the isolation of cavities from saliva decreased the pH, indicating a possible diffusion of acids from within the depths of the decayed material.

Strontium and Fluoride Content of Surface and Inner Enamel versus Caries Prevalence in the Atlantic Coast of the United States of America

Acid-etched samples of surface, subsurface and inner lingual enamel and buccal whole enamel samples were analyzed for strontium and fluoride. The individuals’ caries prevalence was known. The teeth we

Trace element content of surface and subsurface enamel relative to caries prevalence on the west coast of the United States of America

Abstract The enamel of 87 caries-free first premolars of life-long residents of Montana, California and Oregon aged 12–14 years were analysed for strontium (Sr) and fluoride (F) from the surface inwards, using an acid-etch technique on the extracted teeth. The caries prevalence in the individual and in the geographic area was known. There was a gradient in both Sr and F from the surface inward, with a higher concentration in the surface than in the inner enamel. Teeth from the epidemiologically high-caries California area were lower in fluoride than those from the lower-caries Oregon area. The strontium values were the opposite. The Montana individuals with a lower caries index had a lower strontium content, but a very high fluoride content despite the lack of F and Sr in the water supply. When all the samples were grouped, teeth from low-caries individuals had a remarkably similar Sr content (300–400 parts/10 6 ), and a higher F content in the outer (> 400 parts/10 6 ) and inner (> 200 parts/10 6 ) enamel than all the teeth from high-caries individuals. Teeth from those areas with low selenium vs high selenium content in the forage, showed no difference in either F or Sr, but did show a difference in caries prevalence.

Influence of Carbohydrates on in vitro Lesion Production

Fermenting sucrose, glucose and a simulated baby milk containing sugar and corn syrup produced lesions in enamel in vitro in an artificial mouth (the Orofax) which were significantl