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Biomedical subjects

S R Grobler

Publications and source records attributed to S R Grobler.

69 records · Page 4Linked to original sources
PubMed1982

Calcium, phosphorus, fluoride, and pH levels of human dental plaque from areas of varying fluoride levels.

Plaque calcium, phosphorus, fluoride, and pH in samples obtained from 149 life-long resident children, aged from six to seven and 12 to 13 yr, from one of three naturally fluoridated communities were determined. In general, smaller amounts of phosphorus and fluoride, and larger amounts of calcium and hydrogen ions (lower pH values) are associated with smaller amounts of fluoride in the drinking water supply. Significant differences among the mean pH, fluoride, and Ca/P concentrations both in the six-to-seven- and 12- to 13-year age group were found when comparing the results of the three areas with different levels of fluoride in their drinking water supply.

Adolescent↗
PubMedDate not supplied

Blood lead levels of South African long-distance road-runners.

Road runners are exposed to vehicular exhaust aerosols which are a major source of atmospheric lead pollution in those countries where lead additives are incorporated in petrol. The purpose of this study was twofold: the authors wished to determine the blood lead levels of South African road runners, and they wished to investigate the influence of various environments on such levels. Blood samples were obtained by the finger-prick technique and analyzed for lead by graphite furnace atomic absorption spectrophotometry. The results were analyzed statistically and compared with control samples from a selected urban nonrunning population and a remote rural population, respectively. The mean blood lead levels obtained were 20.1 micrograms/dl, 51.9 micrograms/dl, 45.8 micrograms/dl, and 53.00 micrograms/dl for the rural trainers, urban trainers, Two Oceans pre-race, and Two Oceans post-race samples, respectively. The mean level for the selected urban control was 9.7 micrograms/dl. The results suggest that road runners are exposed to increased lead inhalation and that atmospheric lead levels differ in urban and rural areas of South Africa.

Adult↗
PubMedDate not supplied

Lead reduction of petrol and blood lead concentrations of athletes.

In 1984, it was determined that the blood of long-distance runners in South Africa contained unacceptably high concentrations of lead. Subsequently, the petrol lead level in South Africa was reduced from 0.8 g/l to 0.4 g/l. In view of this reduction, a followup investigation of its effect on the blood lead concentration of South African runners was undertaken. Blood lead samples were analyzed by graphite furnace atomic absorption spectrophotometry. The mean values of blood lead concentrations dropped from 52 to 13 micrograms/dl and from 20 to 8.5 micrograms/dl for the urban and rural trainers, respectively. A highly significant decrease in blood lead levels was found and was mainly attributable to the reduction in the petrol lead levels. The blood lead results for rural trainers indicated that there still exists a certain degree of lead pollution in athletes from nonremote areas.

Adult↗
PubMedDate not supplied

Shear bond strength, microleakage, and confocal studies of 4 amalgam alloy bonding agents.

OBJECTIVE: This study was undertaken to determine the relative shear bond strengths and microleakage of 4 bonding agents to dentin and amalgam and to investigate the bonding to dentin through confocal laser scanning microscopy. METHOD AND MATERIALS: Sixty noncarious molars were restored with 1 of 4 different systems, and the shear bond strengths were determined. For the microleakage study, Class V amalgam restorations were placed in 60 noncarious teeth. The specimens were thermocycled, the teeth were sectioned, and dye penetration was assessed. For confocal examinations, the first component of the bonding adhesives was labeled with rhodamine B. Each of the adhesives was applied to 3 dentin specimens, which were examined under a confocal laser scanning microscope RESULTS: Of the 4 restorative systems tested, AmalgamBond Plus + HPA and Prime & Bond 2.1/base-catalyst showed significantly higher shear bond strengths. Prime & Bond 2.1/base-catalyst had the lowest microleakage value, which was significantly lower than that of AmalgamBond Plus + HPA and AmalgamBond Plus. AmalgamBond Plus + HPA had the highest variation in both the bond strength and microleakage values. Confocal laser scanning microscopy revealed tag formation, penetration of the bonding agents deep into the tubules, and hybrid layer formation for all 4 bonding systems. CONCLUSION: The 2 best systems, Prime & Bond 2.1/base-catalyst and, to a lesser extent, AmalgamBond Plus + HPA, utilized a supplemental bonding agent.

Acrylates↗
PubMedDate not supplied

Degree of fluorosis in areas of South Africa with differing levels of fluoride in drinking water.

The purpose of this study was to study the relationship between degree of fluorosis and varying fluoride concentrations in the drinking water in a relatively dry region in South Africa. A strong positive association was found between drinking water fluoride levels and fluorosis but only up to a level of approximately 2.0 ppm for areas with a high average daily temperature (approximately 79 degrees F). The results indicate that the optimum drinking water fluoride concentration for a region with a high average daily temperature should be less than 1.00 ppm.

Adolescent↗
PubMedDate not supplied

High fruit consumption and the periodontal status of farm workers.

The results of a study on the periodontal health of orchard and vineyard workers on apple, grape, citrus and mixed-variety fruit farms are presented. Workers on grain farms were used as controls. The only significant differences in the diets of the different groups were the very large amounts of fresh fruits eaten by the fruit-farm workers. The CPITN index was used to record the periodontal status. Healthy periodontal sextants (code 0) were significantly less in the citrus group (P less than 0.05) compared to the other groups. However, this group also showed a significantly (p less than 0.05) lower prevalence of deep periodontal pockets than the other groups.

Adolescent↗
PubMedDate not supplied

The effect of a high consumption of citrus fruit and a mixture of other fruits on dental caries in man.

The purpose of this study was to determine the effect of a high intake of citrus fruit or a collection of different varieties of fruit on the caries experience in farm workers. The number of subjects included was: for the citrus-producing group 120 (55 men), for the mixed variety group 95 (49 men) and 50 (25 men) for the grain-producing group (control group). Only farms where the drinking water fluoride concentration was less than 0.10 ppm were selected for the study. The mean daily intake of added sugars (excluding that from the specific fruits to be investigated), was the highest for the control group. The percentage frequency of toothbrushing of the three different groups was comparable and low. Significant differences (p less than 0.05) in the caries experience could be demonstrated between the two age categories (15-34 yr and 35+ yr) within any one of the three groups. Significant (p less than 0.0001) differences in the mean DMFT were found between the control group and each of the fruit-producing groups. No significant differences (p greater than 0.05) could be demonstrated between the two fruit-producing groups. However, the highest DMFT (24.8) was found in the citrus-producing group, with less in the mixed variety fruit group (22.7) and the least in the control group (9.9). The sequence of the order of magnitude of the components (D, M, F) of the DMFT was the same as that for the caries experience as such. It is concluded that a high consumption of various fruits over a long period is associated with a high caries experience.

Adolescent↗
PubMedDate not supplied

The effect of a high consumption of apples or grapes on dental caries and periodontal disease in humans.

The intent of this study was to determine the effect of a high consumption of either apples or grapes on the caries experience (DMFT), and periodontal health. Farm workers employed by apple-producing, grape-producing and grain (control) producing farms in low fluoride areas (F less than 0.10 ppm) were investigated. To avoid contamination, only these farms where either apples, grapes or grain were cultivated solely, were included in the study. The caries incidence was found to be the highest for the apple group (24.2), lower for the grape group (17.4), and the lowest for the control group (9.9). The caries incidence differed statistically significantly (P less than 0.01) among the three groups. A higher caries incidence was found in the group of older subjects (35+ years) than in the 15-34 year old group. In general, for both age groups the control group showed conspicuously the highest number of dentate sextants with advanced periodontitis. Significantly less (P less than 0.01) advanced periodontitis and pocket formation could be seen in the youngest age group (15-34 years) of all three test groups. Thus, to conclude, it was found that the consumption of a high amount of apples and to a lesser degree grapes contributed significantly to dental caries. However, the above fruits had a beneficial effect on the periodontal status.

Adolescent↗
PubMedDate not supplied

The degree of enamel erosion by five different kinds of fruit.

It could be expected that the degree of enamel erosion by different fruits containing different kinds of organic acids, or different ratios of acids, and other different chemical components, will vary. The aim of this study was to investigate the degree of enamel erosion by different kinds of fruits (by determining the depths of enamel removed at different stages) over a period of 40 minutes. Statistically significant differences (p less than 0.05) were found among the slopes of apricot and that of grape, guava, apple, and orange. The results demonstrated that the degree of enamel erosion (etch depth) over a six-minute period had the following sequence: apricot more than grape and guava more than apple and orange; while over a 40-minute period the degree of etch depth was grape greater than apricot greater than guava greater than apple greater than orange. The degree of enamel erosion initiated by a fruit juice, as marketed, was about 5-8 times higher than that of the fruit (minced fruit juice). It also became clear that the degree of enamel erosion by different fruits depended on a combination of factors, such as the pH, amounts, and ratios, as well as the types of organic acids and other chemical components present in the fruits.

Citrus↗