Biography and Education - Willoughby D. Miller was born in Alexandria, Ohio. - He studied mathematics and physics at the University of Michigan. - He traveled to Edinburgh to continue his studies. - Financial problems led him to move to Berlin. - Miller trained as a dentist at the Pennsylvania Dental College. - The college merged with the University of Pennsylvania Department of Dentistry. - Miller graduated in 1879, one of the members of the first graduating class. - He worked in Abbot's dental office in Berlin.

Career and Contributions to Microbiology - Miller became appointed Professor of Operative Dentistry at the University of Berlin. - He worked in the microbiological laboratory of Robert Koch in Berlin. - He developed numerous research projects that introduced modern biological principles to dentistry. - In 1890, Miller formulated the chemo-parasitic theory of caries (tooth decay). - Miller's theory held that caries is caused by acids produced by oral bacteria following fermentation of sugars. - He also proposed the focal infection theory, suggesting a role for oral microorganisms in the development of diseases in other parts of the body.

Impact on Dentistry - Miller's chemo-parasitic theory of caries was later supported by the discovery of Streptococcus mutans as a primary pathogen in caries. - He advocated treating and filling root canals instead of removing teeth. - The concept of oral focal infection lost credibility over time. - However, in the 1980s, associations between periodontal disease and other systemic conditions were discovered. - It is now accepted that oral bacteria can cause disease at remote sites or perturb the immune system.

References and External Links - Shklar and Carranza's book 'Carranza's Clinical Periodontology' provides historical background on periodontology. - A journal article by Resan and Hammond discusses the history of microbiology at the University of Pennsylvania School of Dental Medicine. - The website 'um2017.org' provides a history of dentistry. - The British Medical Journal published an obituary for Miller. - 'Oral Microbiology at a Glance' by Lamont and Jenkinson is a recommended resource.