Is the prevalence of perdiodontal disease declining?

The Set-Up

“The field of Periodontology is dynamic, and the role of the different practitioners is rapidly evolving. It is important for dentists and hygienists to stay on top of the latest research and trends. In this excellent review, Dr. Ryder examines the topic of prevalence of periodontitis from a public health and practical clinical perspective. His observations and recommendations provide a solid foundation for looking at this important topic.”-Dr. Peter Cabrera, Team Lead

One of the most rewarding aspects of being a dental practitioner is that we are all in the midst of an ever-changing profession. Over the past century we have seen our profession move from extraction and tooth replacement, to more sophisticated and esthetically oriented restoration approaches, to caries prevention with fluoridation, sealants, and better patient education and awareness. Now we are at a time where the most advanced tools in regeneration biology, genetics, material sciences and bioengineering are being applied to dentistry.

In the past century, we’ve seen similar changes in the field of periodontology. In particular for the periodontal specialist, the nature of clinical practice has undergone dramatic changes. The most significant change has been a shift in periodontal specialty practices from the treatment of moderate to severe periodontal diseases and conditions, to practices that devote more of their efforts toward implant placement and preparation of implant sites in more complex cases, and to a full range of soft and hard tissue periodontal plastic surgery procedures.

An important question 

With this change in the emphasis of periodontal practice toward these implant and esthetic procedures, an important question for the general practitioner and hygienist is: Does this mean the prevalence of periodontal diseases that we all learned about in school is on the decline?

For those of us who practice in dental school settings or in areas with indigent populations, that answer would be “not really,” as we continue to see and treat patients with more advanced periodontal diseases. Indeed studies have shown the prevalence of periodontal diseases are related to lower socioeconomic status. However, there is an important trend in dentistry that has the general practitioner and hygienist beginning to take on the diagnosis, treatment and maintenance of their patients with periodontal diseases, particularly for those patients with mild to moderate forms of these diseases.

Yet a central question remains: “Is the prevalence of periodontal disease on the decline, particularly in the United States and other developed countries?” In this brief review, we will present our current understanding of current trends in the prevalence of periodontal diseases.

The smoking factor

In looking at the possible trends in periodontal disease prevalence over the past 50-60 years there are several broad developments to consider. These include better public awareness of the role of bacterial plaque in the development of gingival inflammation, and the importance of plaque control in removing this plaque. The current variety and number of advertisements, public educational programs, anti-plaque agents, mechanical toothbrushes and other new designs of oral cleaning devices have certainly led to a decrease in the incidence and prevalence of periodontal diseases.

Equally important in this possible decline in the prevalence of periodontal diseases is the drop in the rates of smoking over the past decades. Indeed numerous studies point to smoking as the major preventable risk factor for the development and severity of periodontal diseases. The decline in periodontal diseases has progressed hand-in-hand with the decline in smoking rates. Some leading researchers, such as Philippe Hujoel at the University of Washington, have characterized the link between smoking and periodontal disease and the subsequent decline in periodontal disease with declines in smoking as the “hidden epidemic of periodontal disease” in the 20th century.

An aging population

On the other hand, the trend toward an aging population in the United States and in other developed countries may seem to counteract these beneficial influences such as education, advertising and declines in tobacco use. In fact, aging may be the most important “non-preventable” risk factor in the extent of periodontal attachment loss. However, it appears that even though our older patients may have more bone loss, clinical attachment loss and/or recession, the bottom line is with good plaque control and frequent and appropriate maintenance recalls, the rates of tooth loss in the elderly are not significantly affected.

How we measure it matters

To be able to say periodontal diseases are on the decline, it is necessary for us to look at large scale surveys taken over several decades. If we look at early studies on the prevalence of periodontal disease there are reports that found up to 87% (in a 1955 survey) of the examined population had chronic destructive periodontal disease.

One of the best examples of these reported declines would be the National Health and Nutrition Examination Survey III, which included periodontal measurements. This survey was done for thousands of subjects from 1988-94, 1999-2000, and 2000-2004, and will be revived for the next survey beginning in 2012.

On the surface the trends in the prevalence of periodontal disease over these time periods was quite dramatic, with rates declining from 35% to 7.3% to 4.2%. However it should be noted the methods for assessing periodontal disease were different in each survey. In particular all of these larger scale surveys used partial probing to measure pocket depths, and/or clinical attachment level approaches that look at selected teeth, selected quadrants, and/or selected surfaces of teeth.

However, several studies have shown that these partial examination techniques may underestimate the true prevalence of periodontal diseases by as much as 70% when compared with full probing/full-mouth examinations. While full-mouth examinations are generally impractical when conducting such a survey on a very large population, there is a need to adopt a standard definition for periodontal diseases.

One such possible clinical definition developed by the American Academy of Periodontology and the Centers for Disease Control and Prevention would use a simple but consistent system for classifying moderate or severe periodontitis in large population studies (Page and Eke 2007) as follows: Severe Periodontitis-2 or more interproximal sites with clinical attachment loss greater or equal to 6 mm (not on the same tooth) and one or more sites with pocket depths greater or equal to 5 mm; Moderate Periodontitis-2 or more interproximal sites with clinical attachment loss greater or equal to 4 mm (not on the same tooth) or 2 or more interproximal sites with pocket depths greater or equal to 5 mm (not on the same tooth); No or Mild Periodontitis-neither “moderate” nor “severe” periodontitis. Hopefully, future studies will use a standard definition and survey approach to define periodontal diseases.

What this all means to the general practitioner and hygienist

Despite all these limitations in measuring periodontal disease trends over time, one can conclude the prevalence of the more severe forms of periodontal disease appear to be on the decline in the United States. Studies have shown that general practitioners still refer patients with severe forms of periodontal disease to a specialist, and treat patients with mild or mild to moderate forms in their own offices.

It is important for general dentists to diagnose, treat and monitor the patients they manage in their practices. This includes a full-mouth probing at the initial visit, reevaluation after initial treatment that would address all possible local and systemic factors (e.g. debridement, plaque control instruction, smoking cessation, etc.), maintaining and monitoring their patients on appropriate recall intervals and referring to a specialist where warranted.

Many general practices adhere to these important principles of diagnosis, treatment, maintenance, reassessment and possible referral. However, studies have shown a considerable proportion of practices do not perform initial full-mouth periodontal exams, and rely instead on radiographs and/or do not keep their periodontal patients on a regular recall maintenance program. Thus, for the current and future general dentist and hygienist, there is an urgent need to improve both the periodontal educational programs in dental and dental hygiene schools, and in strengthening continuing education programs on the diagnosis and treatment of periodontal diseases.

About the Author

Dr. Mark Ryder is a Professor and Chair of Periodontology and Director of the Postgraduate program in Periodontology at the University of California, San Francisco where he has been a faculty member for 31 years. He received his dental and specialty training from the Harvard School of Dental Medicine. He is the author of more than 150 articles, abstracts and book chapters and has lectured extensively in continuing education courses on the diagnosis and treatment of periodontal diseases both in the United States and abroad. He has received awards both from the University of California and from national organizations for his entertaining and informative lectures, and for his contributions to dental education.