Harald Löe

Variations in the Prevalence and Extent of Periodontitis

A national survey of employed adults showed a decrease in the extent and severity of periodontal disease in comparison with findings from earlier studies. Using data from that survey, this report evaluates the association of socioeconomic factors--race, education, income and dental insurance, as well as most recent dental visit--with the prevalence and extent of periodontal disease. Periodontitis was more prevalent and usually more extensive in persons who are black, have less education or had not seen a dentist in three or more years. Having dental insurance was not associated with better periodontal health.

A Quantitative Analysis of the Epithelium-Connective Tissue Interface in Relation to Assessments of the Mitotic Index

This paper describes the individual variations in the length and area of the basement membrane and in the volume of the epithelium. The wide variations in the area of the basement membrane and the total epithelial cell population necessitates the introduction of a new method for calculating mitotic activity and turnover rate. A new mitotic index system is suggested.

Closing Remarks: Microbiological and Immunological Aspects of Oral Diseases

The 9th International Conference on Oral Biology is coming to an end, and it is now my special pleasure to officiate an orderly closing of this meeting. In so doing, I would like to extend to the Colgate-Palmolive Company, to members of the Organizing Committee, and to its chairman, Dr. Ken W. Knox, our sincere appreciation for having put together such a magnificent program. We participants have thoroughly enjoyed ourselves within the intellectual and social framework which you so ably have provided. We thank you for your generous hospitality -which perhaps is best charac terized as a most congenial host-parasite relationship! I would be remiss if I did not especially thank the scientists, who through their presentations have confirmed that oral biological research is clearly found at the frontier of biomedical science. Molecular biology, including monoclonal antibody production and gene splicing, is being applied routinely in efforts to answer critical questions in dental research. Advances in anaerobic microbiology have long been pioneered by oral microbiologists, and so has adherence of micro-organisms as a fundamental phenomenon in oral and other infectious diseases. During this meeting, we have witnessed much progress in the understanding of the mechanisms which bacteria use to adhere selectively to specific surfaces, suggesting new approaches to preventing bacterial attachment, and thus preventing colonization. As an example, we were all intrigued by the possibility of milk inhibiting adherence of pneumococci to pharyngeal epithelium. We have learned about mechanisms of co-existence of bacteria competing for limited amounts of nutrients, and realize that the differences between the circumstances of microbes and those of man are not great. Some of us may have been surprised to learn that Streptococcus mu tans was not the leading acid-producing cell, but was superseded by Streptococcus salivarius. I must admit, however, that I personally took great comfort in the fact that treatment with low levels of chlorhexidine eliminated acid production completely by interfering with the phosphorylation of glucose. There is seemingly no end to what chlorhexidine can do! At any rate, although S. mutans is not the only cariogenic organism, there is a massive amount of data suggesting that a considerable reduction in caries could be attained, if colonization of this organism could be prevented. As this audience would know, most of the industrialized countries of this world are experiencing a dramatic decrease in caries. I have been told that here in Sydney one is seeing an 80% reduction among certain groups of children and adolescents. It is interesting and to some extent dispiriting to realize, however, that for all the advances in caries microbiology, the reduction in caries does not directly result from specific use of this knowledge. As a matter of fact, so far oral microbiology has had little tangible impact on the clinical management of caries. True, the understanding of the etiology of caries and the role played by bacteria in the chain of events leading to dental decay has greatly increased the confidence with which we rationalize our approaches to disease control. However, we have not been able to move this particular body of knowledge in micro-