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Both root fillings with ActivGP and GuttaFlow were removed with nickel-titanium rotary instruments. Enlargement of canals up to two sizes beyond the pre-retreatment size was necessary to minimize the amount of sealer remaining.

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Fifty-nine residents of a chronic hospital (average age 67.9 years) were examined visually for root surface caries. Root lesions were found to be present in 44 of the residents and were located most frequently on the proximal surfaces of anterior teeth. The number of coronal DF surfaces, age and number of retained teeth were the factors found to be helpful in discriminating between persons with and without root surface caries.

The similarity between A. viscosus serotype II and A. naeslundii has been noted by several workers. Apart from many common physiological characteristics, antigenic cross-reactions are known to occur. The increase in the use of these organisms experimentally makes it important to establish the relationships within the type strains, and those of the strains to wild type oral isolates. The results of a total of 65 tests on 43 strains have been subjected to computer analysis and compared to 5 strains of A. israelii. The analysis shows the degree of similarity between A. viscosus serotype II and A. naeslundii to be comparable to that between the two serotypes of A. israelii. Comparisons have also been drawn on the basis of antigenic structure, these have shown that cell wall carbohydrate antigens are shared by strains of both A. naeslundii and A. viscosus although specific antigens do exist. The results of the study indicate that human strains of A. viscosus and strains of A. naeslundii are closely related and that further consideration should be given to the validity of their present separation into 2 species. Within this group of organisms, however, variations do exist which should be considered when selecting strains for experiments relating to the human oral situation. Strains should be selected that are representative of commonly occurring isolates rather than those peripheral to the group.

Intact root surfaces of chronically hospitalized subjects were sampled periodically to enumerate bacterial species believed to be associated with root caries. Bacteria were cultivated and enumerated using a series of selective and enriched media. Microbial counts, isolation frequencies, and percent cultivable flora data were analyzed for caries-active and caries-free surfaces and subjects. S. mutans, S. sanguis, A. viscosus, A. naeslundii, total lactobacilli, and Veillonella accounted for a mean of less than 20% of the cultivated flora, with mitis salivarius agar cultivable streptococci averaging less than 5%. The microbial count data were highly variable, precluding the finding of significant differences in caries association for either subjects or sites. Streptococci, especially S. mutans, correlated highly with lactobacilli in the samples.

1. During the two-year period, caries developed at 20% of the target premolar sites. The attack rate for these surfaces was similar in the plaque panel and the other subjects in the study. 2. The microbial composition of plaque samples from caries-free sites and from carious sites before and after radiographic detection of lesions was broadly similar. 3. Numerical domination of particular sites by S mutans before detection of caries can occur, but has only been observed so far in 2 of 15 sites. 4. Pooled date from sites which have developed lesions indicate a rise in the isolation frequency and mean numbers of S. mutans after detection of caries. This trend was particularly obvious in the one subject who developed bilateral lesions by the second examination and in three of four sites where caries was detected at the fourth examination. Similar observations have been made with lactobacilli. 5. In two of 15 instances no isolations of S mutans were made from sites which developed caries. 6. To date, no single species appears to be uniquely associated with the onset of dental caries.