John J. Hefferren

A Laboratory Method for Assessment of Dentrifrice Abrasivity

This is the report of the Laboratory Abrasion Committee of the American Dental Association (ADA) Dentifrice Program relative to specific methods to measure the in vitro abrasivity of dentifrices. This method was used in two collaborative studies with six participating laboratories. These studies were designed by the ADA Dentifrice Program Statistical Committee and their interpretations form a basis for recommendations on the use of the method. This laboratory method is recommended for use in dentifrice development and may provide some basis for expectations in normal dentifrice use.

Cariostatic Evaluation of Cheeses with Diverse Physical and Compositional Characteristics

The caries-inhibitory potential of four cheeses with different permutations of texture, aging, levels of butterfat, protein, calcium, phosphate and lactose were evaluated in a rat caries test using a

Modification of Food Cariogenicity in Rats by Mineral-rich Concentrates from Milk

Dairy products, including milk, cheese, and casein, can reduce the caries-causing potential of cariogenic substrates as measured in various animal, plaque acidity, and in vitro systems. Although the mechanisms responsible for protection are not completely identified, substances containing Ca and P may contribute to the protective potential by reducing demineralization and/or promoting remineralization of enamel. Casein may reduce demineralization by forming a protective coat on the enamel surface. By means of a rat model, this study evaluated the ability of three casein-free milk mineral concentrates with various levels of whey protein, calcium, and phosphate to modify the cariogenicity of a powdered diet containing 20% sucrose. Analysis of these data indicates that there were no significant differences among groups for weight gain, total food consumption, or feeding frequency, as monitored by a computer-based infrared activity monitor. All three mineral concentrates significantly reduced buccal caries, and two of the three reduced sulcal caries by from 10 to 30%. The analysis further shows that casein-free milk mineral fractions can modify the cariogenicity of sucrose-containing foods in a rat model.

Study of Fluorescent Characteristics of Extracted Human Teeth by Use of a Clinical Fluorometer

The native fluorescence of clinically sound extracted human teeth was determined with a filter fluorometer fitted with a fiber optic probe. To establish the normal range of fluorescence, ten teeth of each tooth type from the mandibular and maxillary arch, respectively, were examined. Differences in the fluorescence were observed at various areas of the same tooth and between various types of teeth.

Dental cariogenic evaluation of foods using human plaque pH and an experimental rat-caries model

Five well-characterized foods were used to compare two systems for estimating the cariogenic potential of food: human plaque-acidity using interdental metallic touch electrodes, and cariogenicity testing in rats. Both systems identified the same food as the least cariogenic or acidogenic food and identified the same three foods as being both cariogenic in rats and acidogenic in man, although the ranking of these foods differed. The systems differed in their assessment of potato chips, a food high in cooked starch and low in free sugars. The results confirmed that non-acidogenic foods are non-cariogenic, but that foods acidogenic in man may exhibit a greater range of cariogenicity in rats. Data from both human plaque pH studies and rat caries models may permit better assessment of cariogenic potential of foods containing fermentable carbohydrates.

Reactions of Stannous Fluoride with Some Inorganic Compounds

SYNOPSIS IN INTERLINGUA REACTIONES DE FLUORURO STANNOSE CON CERTE COMPOSITOS INORGANIC.—Le hic-reportate studios del chimia de SnFl concerneva su reactiones con varie cationes, incluse Ba, Ca, Na, e St e altere species que exerce un distincte effecto in le pH. Le concentrationes de solubile iones stannose e fluoruric esseva determinate in liquido supernatante de suspensiones de 0,4 pro cento de SnFl, e iste compositos inorganic esseva studiate como function del tempore. Compositos que augmentava le pH o que provideva un cation que forma un fluoruro insolubile reduceva le concentration de solubile iones stannose. Le concentration de solubile iones fluoruric non esseva un function del pH.

A New Abrasive Applicator for Human Enamel Biopsy Procedures

Experiments were performed that demonstrated that the felt cylinder usually used to obtain abrasive biopsy specimens did not uniformly remove enamel from rounded or irregular enamel surfaces in the window area. A foam-silicone rubber laminate was developed to replace the felt cylinder. This resulted in greater uniformity of abrasion over the enamel surface within the biopsy window area and better operator handling characteristics.

Peptide Mapping of Partial Acid Hydrolysates of Human Dentin and Bovine Skin Collagens by Thin-Layer Methods

Human dentin and bovine skin collagens, partially hydrolyzed with acid, were compared by peptide mapping on thin-layer plates. The patterns, which showed 20 to 25 spots, were similar for the two types of collagen. No major differences in the structural characteristics of dentin and skin collagens can be predicted from these results.

Determination of Tin in Enamel and Dentin by Atomic Absorption Spectroscopy

The determination of tin by atomic absorption spectroscopy was developed to such a degree that it could be applied to the analysis of tin in dental tissues at the 1 ppm level. This development involved the elimination of the interference due to calcium and its phosphates and the improvement of operating conditions to maximize sensitivity. By use of this method, tin was determined in untreated and stannous fluoride-treated powdered and intact enamel and dentin.

Preparation of Large Quantities of Powdered Enamel

Powdered enamel of extracted human teeth has been used in the estimation of the activity of anticaries agents (S. D. GERSHON, 0. W. NEIDITCH, and R. H. C. LEE, Proc. Toilet Goods Ass., 28:14-17, 1957), as well as a number of studies with a direct or indirect relation to this activity. Correlation of results with different samples of enamel has been difficult because of the numerous variables. In order to minimize these variables, it has been desirable to carry out certain phases of a study with the same batch of enamel. Rather than powder a large number of teeth by hand with a diamond mortar or other suitable instrument, various mechanical means of powdering teeth were explored, so that a relatively large sample of enamel could be obtained conveniently. An Abbe ball mill filled with flint stones ground the teeth to a very fine powder, but the grinding process was very slow. The particle size of the ground material was primarily coarse (>60 mesh) or very fine (<325 mesh): thus the desired graduation in particle size was not obtained. A Model M Fitz Mill,* a stainlesssteel, blade-type hammer mill used extensively in pharmaceutical work, quickly ground the crowns into a variety of mesh sizes. In order to reduce the temperature build-up during the grinding operation and to increase the brittleness of the crowns, powdered dry ice, or preferably, liquid nitrogen was used to cool the crowns prior to grinding. This mixture was then added directly to the mill. The results of two runs with a 60-mesh sizing screen on the hammer mill are given in the table.