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Famed dental researcher Dr. Paul Keyes dies

Educator came into national spotlight for controversial periodontal treatment regimen

February 20, 2017

By Michelle Manchir

Dr. Keyes
Dr. Paul H. Keyes, an innovative researcher and educator who garnered national fame and sparked dental community debate after developing a first-of-its-kind nonsurgical therapy for gum disease, died Feb. 7. He was 99.

Dr. Keyes was among the first to employ anti-infective agents and microbiological testing in nonsurgical periodontal therapy, including patient home irrigation with baking soda or salt solutions, and brushing with a mix of baking soda and hydrogen peroxide. 

The approach, popularly known as the Keyes technique and dubbed in some popular media the “salt-and-soda” method, also involved traditional methods of root scaling   and plaque control supplemented with professional pocket irrigation with antiseptic agents, potential use of short-term systemic antibiotic therapy in severely-affected patients and examination of subgingival plaque morphotypes with a microscope to help guide therapy and motivate patients.

The approach inspired widespread discussion in the early 1980s — not only in dental research communities, but also among the general public, becoming the subject of articles in The New York Times, People Magazine and other national media. The ADA News wrote about the method in its June 1981 issue, when the now-extinct U.S. Office of Technology Assessment presented it in a report to Congress. The article drew a flurry of letters from ADA member readers, some promoting the technique while others calling for more evidence of its effectiveness.

“Eventually, many aspects of the technique were found to be supported by a number of subsequent research studies involving patients with severe periodontitis, but it remains controversial,” said Dr. Thomas Rams, professor of periodontology and oral implantology at Temple University Kornberg School of Dentistry in Philadelphia, and a longtime research collaborator with Dr. Keyes.

“The widespread use of baking soda in toothpastes and home oral hygiene regimens is largely attributable to the impact of Paul Keyes,” said Dr. Rams.

Before entering the spotlight with his perio research, Dr. Keyes left a legacy as a research investigator on human periodontal disease and dental caries at the National Institute of Dental Research (a branch of the National Institutes of Health) from 1954 to 1981.

His investigations “fundamentally changed our understanding of the two most common diseases affecting populations,” said Dr. Christopher Fox, director of the International Association for Dental Research/American Association for Dental Research. “Long before today’s microbiologic tools were available, Dr. Keyes applied scientific rigor with simple elegant experiments to prove or disprove his hypotheses.”

Dr. Keyes pioneered the use of Syrian hamsters in the 1940s as the first reliable animal model to study dental caries and periodontal disease, according to Dr. Rams. Dr. Keyes and Dr. Robert Fitzgerald were the first to document in 1960 the etiologic role and infectious transmission of mutans streptococci in the development of dental caries, according to Dr. Rams. In 1977, Drs. Keyes and Fitzgerald shared the inaugural Research in Dental Caries Award from the International Association for Dental Research.

After a request from the Peace Corps in the early 1960s, Dr. Keyes invented customized vinyl trays and fluoride gels for daily home self-application, according to Dr. Rams.

In periodontal research, Dr. Keyes is credited by Dr. Rams with first documenting in 1946 the essential role of dental plaque in the onset of experimental periodontitis. Later, Dr. Keyes and co-authors were the first to show microbial transmission and specificity in the etiology of experimental periodontitis, and conducted the first double-blind clinical trial of systemic tetracycline in human periodontitis therapy.

Also a public health advocate and educator, Dr. Keyes founded and led the International Dental Health Foundation, which operated until the early 2000s, and held adjunct faculty appointments at Georgetown University School of Dentistry and at Temple University, where a term professorship in periodontology was established in his name by a former patient from 2003-13, said Dr. Rams.

Dr. Keyes was preceded in death by his wife, Doris Jean Keyes, in 2015 at the age of 101, said Dr. Rams. He is survived by four children, eight grandchildren and eight great-grandchildren.

For Dr. Rams, that many of Dr. Keyes research discoveries “remain part of dental education and clinical practice today is a tribute to his intellectual prowess, personal tenacity, and the scientific virtue of his approaches to unraveling unknown aspects of dental caries and periodontal disease.”