An ultrastructural quantitative study of the significance of microbial multiplication during early dental plaque growth

A comparison of 4 techniques for clinical detection of early plaque formed during different dietary regimes

The purpose of this study was to evaluate the sensitivity of 4 clinical techniques used in detecting early plaque during a period of dietary sucrose restriction and during a period of sucrose supplementation. The accumulation of plaque during experimental periods of 3 h, 6 h and 18 h was recorded in a group of 38 dental personnel for the 1st part of the study, and in a group of 32 for the 2nd part. Plaque levels were assessed using a caries probe, a plaque detection probe, erythrosin and a 2-tone disclosing agent. There was a progressive increase in plaque over the period of the study, with significant variation between the detection methods used and the sites being assessed. Plaque formed more rapidly interdentially and on the posterior teeth. 3 h after the teeth had been thoroughly cleaned, plaque was detectable on over 12% of sites for the sucrose-restricted diet and on up to 23% of sites for the sucrose-supplemented diet. After 18 h of plaque formation, the proportion of plaque-covered surfaces had increased to between 52% and 73%. For minimal amounts of plaque, the disclosing solutions were found to be the most sensitive assessment techniques. However, for moderate and abundant plaque deposits, the techniques using the probes resulted in a greater degree of differentiation in the proportional measurements of plaque. Overall, the plaque probe was found to be as sensitive or better than the other techniques under most conditions and was favoured on clinical grounds, as it aided access to the interdental areas and provided a contrasting colour at the tip to enable plaque to be detected with greater ease.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of diet on the growth of streptococcal bacteria on the molar teeth of monkeys (Macaca fascicularis)

The rates of regrowth of bacteria in developmental grooves on these teeth were determined. Plaque was removed from palatal grooves up to 96 h after cleaning and the number of bacteria and of individual streptococcal species were determined; Streptococcus sanguis, Streptococcus mutans and Streptococcus mitior were the major ones. In monkeys fed one of three different diets, the numbers of each species reached stable levels 18-24 h after tooth cleaning. The median doubling times of the streptococcal population were 4.69, 3.82 and 4.25 h for two maintenance diets and a sucrose diet, respectively. The median doubling times of individual species ranged from 2.01 to 4.38 h and appeared to be independent of the composition of the various diets. There was no difference in the number of bacteria in 18 h-old plaque from discrete sites in fed or fasted monkeys, nor in the numbers of streptococci, except that the size of the Strep. mitior population increased significantly with fasting. Thus host-derived substrates, possibly salivary components, may be used by plaque bacteria and support their on growth in developmental grooves in the absence of food.

Formation and ecology of plaque at different locations in the mouth

Some recent findings concerning microbial colonization of smooth surfaces of teeth, gingival crevices, occlusal fissures and removable dentures are reviewed considering the many ecologic factors of importance for the oral microbial communities. The oral microbiota is extremely complex comprising at least 200 taxa. In spite of interindividual and site-to-site variations, each oral habitat has a characteristic microbiota ranging from Gram-positive, facultatively anaerobic cocci and rods in occlusal fissures to predominance of Gram-negative, strictly anaerobic rods and spirochetes in deep periodontal pockets.

Effect of chlorhexidine rinses on the morphology of early dental plaque formed on plastic film

The effect of chlorhexidine on early plaque formation was studied in vivo in order to assess potential structural and quantitative changes. 3 subjects with healthy gingiva were used. Plastic films were applied to the buccal surfaces of the maxillary right first premolars and plaque was allowed to form for either 4 or 24 h. A single 1-min rinse with 0.2% chlorhexidine digluconate was used for the 4-h experiments, 1 min after film placement, whereas, for the 24-h experiments, an additional 1 min rinse was used at 12 h. In total, 62 films were obtained, half treated and half controls. These were processed for light and transmission electron microscopy, using standardized techniques for area sampling and cell counting. All plastic films were covered by a surface coating of acellular material in or on which bacteria, epithelial cells and leukocytes were observed. In the controls, an important increase in bacterial count was seen between 4 and 24 h, whereas the increase with chlorhexidine was slight. There were fewer bacteria in the chlorhexidine as compared to the water specimens, for both time periods. Many microorganisms in the chlorhexidine samples appeared to be undergoing degeneration with coagulated cytoplasm and disrupted cell walls.