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Clinical General Dentistry

Non-controlled type 2 diabetes in a 42-year-old patient.
Jan 7, 2011 | General Dentistry USA

Systemic and dental factors affecting the prognosis of teeth

by Belinda Brown-Joseph, DMD, MS; Samia Hardan, DDS, MS; David L. Hoexter, DMD, FACD; Sebastien Dujardin, DDS, MS; and Jon B. Suzuki, DDS, PhD, MBA

The greatest challenge in treatment planning is to assign a predictable accurate prognosis. In the era of evidence-based dentistry, outcome studies have forced us to re-examine our treatment approaches. Periodontal prognosis refers to the expected longevity of teeth. Determination of periodontal prognosis is an integral part of periodontal practice and it influences treatment planning directly whether to treat, retain or remove periodontally involved teeth.1,2

The prognosis of whole dentitions or individual teeth is “dynamic” and may require alteration of projections as health status or dental initiatives (e.g., oral hygiene) change.

While many considerations from the periodontal literature apply, new information and techniques should be considered to retain teeth or not.2

This article focuses on the primary areas for consideration of development of prognosis with the underlining goal of patient and clinical satisfaction and economic stability.

Periodontal prognostication systems

Historically, the prognosis of a tooth was defined based on tooth loss.3,4 Several authors have formulated and investigated their own prognostication systems with variable results, but showed that systems based on tooth loss were unpredictable over the long term.1

The accepted, and generally used, classification of prognosis was suggested by McGuire and Nunn.5 This system contains a detailed stratification for individual teeth as seen in Table 1.

Another system was introduced by Kwok and Caton, which determines prognosis on future periodontal stability.1,6 Prognosis is considered “favorable” for teeth when the local or systemic factors can be controlled and the periodontal status of the tooth can be stabilized with comprehensive periodontal treatment and maintenance.

When the local or systemic factors may or may not be controlled, teeth are determined to have a “questionable” prognosis, although the periodontium can be stabilized with comprehensive periodontal treatment and periodontal maintenance if these factors are controlled.

For teeth with an “unfavorable” prognosis, the local or systemic factors cannot be controlled, and periodontal breakdown is likely to occur even with comprehensive periodontal treatment and maintenance. Finally, when the prognosis is “hopeless,” extraction is indicated.

Overall versus individual tooth prognosis

When projecting prognosis, many factors are to be evaluated. These factors are then synthesized into a scheme for determining a periodontal prognosis. Although longitudinal studies have indicated that non-surgical and surgical treatments generally were maintainable, long-term stability is still subject to many variables.1,7–11

As shown in Table 2, factors influencing the overall periodontal prognosis include age, genetics, oral hygiene, systemic conditions, smoking, patient compliance and economic consideration.

Tooth-specific influences include the amount of attachment loss, crown-root ratio, position in the arch, presence or absence of furcation invasions and other anatomic and restorative factors.2,8 These parameters are recorded and weighed according to past clinical experience and prognosis is assigned.12

Overall prognosis

Factors that need to be considered when deciding on an overall periodontal prognosis include the following.

Age. Studies consistently show more periodontal disease and generally greater severity of disease in older as opposed to younger people.1,2,6 Generally, an older patient probably has a better prognosis for a given level of attachment loss than a younger patient does.

Plaque control. Bacterial plaque is the primary etiologic factor associated with periodontal disease. The patient’s ability to perform adequate plaque control is important in determining whether or not the disease can be arrested.2,6,13

Smoking. Individuals who smoke more than 10 cigarettes per day have an increased risk of more severe periodontal disease, a less predictable response to initial therapy and a more complicated therapeutic response. With all other factors being equal, a patient who continues to smoke will have a worse prognosis than one who either does not smoke or quits smoking.14–17

Diabetes. Diabetic patients have a higher prevalence of periodontal disease and greater attachment and bone loss.18,19 Patients with diabetes, especially poorly controlled diabetes, will generally have a worse overall prognosis than patients who are not diabetic (Fig. 1).

Genetics. Genetic factors may play an important role in determining the nature of the host response. It was suggested that genetic polymorphisms in certain genes involved in the immune response (e.g., interleukins IL-1 and IL-10 ), may be associated with susceptibility to severe periodontitis in some populations.6,12

Stress. Physical and emotional stress as well as substance abuse may alter the patient’s ability to respond to the periodontal treatment performed.6 A recent meta analysis of the literature suggests that psychological stress can lead to increased periodontal disease.2,20

Patient compliance. One should consider the patient’s ability and consistency in performing plaque control when determining the overall prognosis. The better his or her plaque control, the better the long-term prognosis.21–23 This determination is an important part of the re-evaluation examination following initial root planning and oral hygiene instructions.1,2,6

Economic consideration. Persons with severe periodontal disease are likely to be less conscious of their health, resulting in a worse prognosis. The complex treatment of patients with advanced periodontal breakdown is very expensive.24

Prognosis for individual teeth

The prognosis for individual teeth is determined after the overall prognosis and is affected by it. Many local and prosthetic/restorative factors have a direct effect on the prognosis for individual teeth in addition to any overall systemic or environmental factors that may be present.1,2,5,6

It was found that attachment loss, probing depth, furcation involvement, crown-to-root ratio, fixed abutment status and percent bone loss are the most important factors in determining tooth loss.5,25

Deep probing depth and attachment loss. Deep probing depths and attachment loss are associated with future periodontal breakdown due to limited access for maintenance and opportunistic changes in the environment to favor periodontal pathogens.1,26,27 Probing depths greater than 5 mm were difficult to maintain as healthy and had more residual plaque and calculus.28

Crown-root ratio. Crown-root ratio is also a measure of attachment loss, especially when dealing with short roots. The example on this page demonstrates poor crown-root ratio related to a developmental anomaly in a patient with short roots (Fig. 2).

Furcation invasions. The greater the amount of attachment loss in the furcation, the worse the long-term prognosis for that tooth. Teeth with minimal (Class I) or no furcation invasions generally have a good prognosis.

Teeth with complete loss of bone in the coronal aspect of the furcation (Class III) generally have a poor prognosis, and regeneration of this type of defect is not predictable for most clinical situations. Therefore, teeth with Class III furcation have an unfavorable treatment outcome.2,8

Anatomic factors. Teeth such as the maxillary premolars, which have pronounced root concavities, are also more difficult to instrument and maintain, and likewise have a worse prognosis than teeth with relatively straight roots.8

Tooth mobility. While some authors have found that increased mobility is a factor that negatively influences the survival of a periodontally affected tooth5, others describe no association between tooth mobility and treatment outcome. Severe mobility of a tooth is generally an indicator of a poor long-term prognosis.1,2

Restorative and prosthetic factors. Overhanging restorations and ill-fitting crown margins represent an area for plaque retention and increased prevalence of periodontal lesions.29

Depending on the supragingival or subgingival location of such factors, their influence on the risk for disease progression and periodontal prognosis has to be considered.30

Fixed abutment status is a measure of occlusal load and also of the patient’s ability to perform plaque control.2


Developing a prognosis for the dentition incorporates virtually all skills in the art and science of dentistry. Prognosis can be stratified in the prognosis of the overall dentition and prognosis of individual teeth.

Prognosis should primarily have a scientific and evidence-based approach that also is predicated upon clinical experience, individual patient factors and luck.

Development of an accurate prognosis has an underlining economic importance. Prognosis of the overall dentition leaves clinicians and patients to choose appropriate treatment plans based on the expected lifetime of teeth.

For example, if the majority of teeth have a poor or questionable prognosis, treatment plan options may favor full-mouth extraction and complete dentures. Another patient with the majority of teeth with a poor or questionable prognosis may be motivated for dental implants and a fixed prosthesis.

Development of a prognosis for individual teeth or combined with dental implant treatments may add levels of complexity to the treatment plan and have far reaching economic consequences. Utilizing natural teeth as abutments for a fixed prosthesis or individual crowns must be reasonable.

Patient issues such as overall health, impacted medications, dental IQ, oral hygiene, etc., need to be assessed prior to dental therapies and reviewed at each exam and recall appointment.

The determination of a prognosis is an evolving and dynamic process. Therefore, it is reasonable to try to predict a long-term prognosis, but reassessment is often needed for a prolonged period.

Therefore, reprognostication occurs after each examination of the patient.

About the authors

  • Dr. Belinda Brown-Joseph is director of the graduate periodontal clinic and associate professor of periodontology and oral implantology at Kornberg School of Dentistry at Temple University, Philadelphia.
  • Dr. Samia Hardan is an assistant clinical professor of periodontology and oral implantology at Kornberg School of Dentistry at Temple University, Philadelphia.
  • Dr. David L. Hoexter is a clinical professor of periodontology and implantology at Temple University School of Dentistry, Philadelphia, and editor in chief of the Dental Tribune U.S. Edition
  • Dr. Sebastien Dujardin maintains a private practice in periodontics in Lille, France.
  • Dr. Jon B. Suzuki is a professor of microbiology and immunology at the School of Medicine, Temple University, and professor of periodontology and oral implantology at Kornberg School of Dentistry at Temple University, Philadelphia.

A complete list of references is available from the publisher. 

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