Risk assessment for periodontal disease.

The prevention and treatment of periodontal disease is based on accurate diagnosis, reduction or elimination of causative agents, risk management and correction of the harmful effects of the disease. The practice of risk assessment involves dental care providers identifying patients and populations at increased risk of developing periodontal disease. This can have a significant impact on clinical decision making. Risk assessment reduces the need for complex periodontal therapy, improve patient outcome and, ultimately, reduce oral health care cost. The awareness of risk factors also helps with the identification and treatment of co-morbidities in the general population as many periodontal disease risk factors are common to other chronic diseases such as diabetes, cardiovascular diseases and stroke.

INTRODUCTION

Over the last three decades, our understanding on the pathogenesis and etiology of periodontal diseases has grown greatly. Numerous studies have demonstrated that the host plays a major role in the pathobiology of periodontitis and that risk varies greatly from one individual to another.[1] Identifying risk factors and indicators, as well as undertaking measures that can reduce the risk, can help in maintaining oral health and prevent the onset of any form of periodontal disease. Risk management involves dental care providers to identify patients and populations at increased risk of developing periodontal disease. Assessing patients risk of developing periodontal disease can have a significant impact on clinical decision making. Some risk factors can be modified to reduce one's risk of initiation or progression of disease, such as smoking or improved oral hygiene, while other factors cannot be modified, such as genetic factors.[2]

Risk factors for periodontal disease

Risk can be identified in terms of risk factors, risk indicators or risk predictors. A risk factor is thought to be a cause for a disease. It should satisfy two criteria: (1) it is biologically plausible as a casual agent for disease and (2) it has been shown to precede the development of disease in prospective clinical studies. Risk factors are biologically related to the occurrence of the disease, but they do not necessarily imply cause and effect, i.e. just because a patient possesses a risk factor does not mean that they will definitely develop the disease. Equally, absence of a risk factor does not mean that the disease will not develop. Evidence in the literature points to the direct and significant link between several risk factors and periodontal disease.[3]

Risk factors may be broadly categorized as:

Systemic risk factors - factors that affect the host response to the plaque biofilm, upsetting the host-microbial balance.

Local risk factors - factors local to the oral cavity, which may influence plaque accumulation or occlusal forces.[4]

Age

As people age, their risk for developing periodontal disease increases. Over half of the adult population has gingivitis, a less severe form of periodontal disease surrounding three to four teeth, and nearly 30% have significant periodontal disease. In a study of people over 70 years old, 86% had at least moderate periodontitis or a severe form of periodontal disease, and over one-fourth of this 86% had lost their teeth. The study also showed that the disease accounted for a majority of tooth extractions in patients older than 35 years of age.[56]

Use of tobacco

A wealth of data has established the relationship between the amount and duration of smoking and the severity of periodontal pathology. Both local and systemic mechanisms mediate the negative impact of tobacco use on oral health. Heat from smoke may enhance attachment loss, and the increased calculus deposits that often result from smoking can enhance plaque retention. Nicotine can diminish collagen synthesis and protein secretion and inhibit bone formation. These findings result in impaired wound healing as well as increased susceptibility to periodontal disease, which may limit the success of treatment interventions. Smoking also inhibits immunological function and negatively affects immunoglobulin levels, which may increase susceptibility to typical and unusual microbial pathogens.[7]

A number of studies indicate that the nicotine found in tobacco products triggers the overproduction of cytokines in the body due to lowered oxygen levels. Cytokines are signaling chemicals involved in the process of periodontal inflammation. When nicotine combines with oral bacteria, such as P. gingivalis, it results in higher levels of cytokines, leading to breakdown of the supporting tissues of the teeth. Studies suggest that smokers are 11-times more likely than non-smokers to harbor the bacteria that cause periodontal disease and four-times more likely to have advanced periodontitis. In one study, over 40% of smokers had lost their teeth by the end of their lives. The risk of periodontal disease increases with the number of cigarettes smoked per day. It is important to note that smoking cigars and pipes carries the same risk as smoking cigarettes.[89]

Diabetes mellitus

There is much evidence showing a link between type 1 and 2 diabetes mellitus and periodontitis. Diabetes has been associated with a number of oral complications, including gingivitis and periodontitis, dental caries, salivary gland dysfunction and xerostomia, burning mouth syndrome and increased susceptibility to oral infections. Of particular concern are patients with diabetes who are at an increased risk of developing periodontitis. In these patients, host responses may be impaired, wound healing is delayed and collagenolytic activity may be enhanced. As a result, periodontitis may be a particular problem in patients with diabetes, especially in those with uncontrolled disease.[10]

Diabetes may also contribute to the pathogenesis of periodontitis via associated vascular compromise, deficits in cell-mediated immunity and the presence of a high glucose content in the blood, which enhances bacterial growth. Furthermore, active inflammation characteristics of periodontitis generates compounds that may increase insulin resistance. Therefore, control of periodontal disease may help patients improve metabolic control. Obesity, which is common in type 2 diabetes, may also predispose a person to periodontal diseases.[1112]

Stress

It has been strongly suggested that stress and related body distress are important risk indicators for periodontal disease. A recent study shows that people under physical or psychological stress are prone to elevated biofilm plaque levels and increased gingivitis.[13] It also seems likely that high levels of financial stress and poor coping abilities increase the likelihood of developing periodontal disease two-fold. Furthermore, it is likely that systemic disease associated with periodontal disease such as diabetes, cardiovascular diseases, pre-term delivery and osteoporosis may share psychosocial stress as a common risk factor. However, a direct association between periodontal disease and stress remains unproven.[14]

Genetic risk factors

In recent years, genetic markers have become available to determine various genotypes of patients regarding their susceptibility to periodontal diseases. Research on the Interleukin-1 (IL-1) polymorphisms has indicated that IL-1 genotype-positive patients show more advanced periodintitis lesion that IL-1 genotype-negative patients of the same age group. Also there is a trend to higher tooth loss in the IL-1 genotype-positive subjects. In a retrospective analysis of over 300 well-maintained periodontal patients, the IL-1 genotype yield higher BOP% during a 1-year recall period than the IL-1 genotype-negative control patients. This supports the theory that specific environmental factors can be strong risk factors and that they overwhelm any genetically determined susceptibility or resistance to disease.[1516]

Pregnancy

Periodontal disease has been shown to be associated with pre-term delivery and low birth weight, both of which put infants at risk of experiencing increased medical complications. Analysis of gingival crevicular fluid has demonstrated significantly higher levels of the inflammatory mediator prostaglandin E2 in women who delivered pre-term low birth weight infants. However, other research has failed to demonstrate a link between pre-term low birth weight babies and periodontal disease.[1718]

Cardiovascular diseases

Cardiovascular diseases affect adults, and there is evidence that links periodontitis and cardiovascular diseases. C-reactive protein is a systemic marker for inflammation. The plasma levels of this marker are predictive of future myocardial infarct and stroke. Patients with periodontitis have demonstrated elevated C-reactive protein levels. Some investigators have suggested that the chronic inflammatory burden of periodontitis may contribute to cardiovascular diseases.[19] In an analysis of 4561 subgingival plaque samples collected from 657 subjects, Desvarieux and colleagues found a direct relationship between periodontal bacterial burden and subclinical atherosclerosis. Other reports have noted associations between cerebrovascular stroke and tooth loss, bone loss and poor dental status, although the precise mechanisms that mediate these multiple pathogenic processes have not been delineated.[20]

Poor oral hygiene as a risk factor

Many studies have demonstrated significant reductions in probing pocket depths, attachment gains and, of course, in gingival inflammation, with improvements in oral hygiene alone. The lack of oral hygiene encourages bacterial build-up and biofilm plaque formation, and can also increase certain species of pathogenic bacteria associated with more severe forms of periodontal diseases.[21]

Risk indicators

A risk indicator is a factor that is biologically plausible as a causative agent for a disease but has only been shown to be associated with disease in cross-sectional studies. An example of a risk indicator of periodontal disease is the presence of herpes viruses in subgingival plaque. A risk predictor is a factor that has no current biological plausibility as a causative agent but has been associated with disease on a cross-sectional or longitudinal basis. Example, the number of missing teeth is a risk predictor for disease, but has little or no plausibility as a causative agent for periodontitis.[3]

Risk assessment

According to the American Academy of Periodontology, risk assessment has been defined as the process by which qualitative or quantitative assessments are made of the likelihood for adverse events to occur as a result of exposure to specified health hazards or by the absence of beneficial influences.[22]

One of the problems with risk assessment in periodontal disease is that the diseases are multifactorial and assessment should therefore be at multiple levels. The presence of pathogenic bacteria alone is not sufficient to cause the disease. In simple terms, there are four levels to consider:

The patient level - Perform at initial examination

The whole mouth level - Perform at initial examination and post-initial therapy

The tooth level - Perform post-initial/definitive therapy and maintenance

The site level - Perform post-definitive therapy and during maintenance

This approach also allows the clinician to separate risk factors that may initiate periodontal disease from those responsible for its progression or for the failure of initial therapy.[2324]

Patient-level risk assessment

Patient-level risk assessment can be determined at the initial consultation by performing the following:

Family history for hereditary, inborn or genetic risk factors. Take a detailed history of gum disease or early tooth loss in the family.

Medical history for systemic diseases, e.g. diabetes mellitus, cardiovascular diseases, osteoporosis

Present dental history - Assess motivation to oral hygiene.

Social history, which includes smoking - current or former smoker

Habits like bruxism.

Mouth-level risk assessment

Mouth-level risk assessment would be performed at the initial examination, after a basic periodontal examination, and would include:

Examination of attachment loss relative to age

Occlusal examination in static relationship

Occlusal examination in dynamic relationship

Examination of levels of oral hygiene

Examination of levels of plaque-retentive factors

Presence of removable prosthesis

Levels of recession

Gingival inflammation and depth of pockets.

Tooth-level risk assessment

Tooth-level risk assessment may or may not be carried out at the initial examination. A detailed periodontal chart and radiographic assessment should be performed. Part of this assessment includes:

Individual tooth mobility (mobility index)

Tooth movement or drifting of periodontally compromised teeth

Residual tooth support (radiographically). The extent of residual radio graphic bone support helps determine long-term prognosis.

Presence, location and extent of furcation lesions

Individual tooth anatomy - Presence of "talon cusps" or bulbous crowns

Anatomy of tooth embrasures and contact points

Presence of ledges or deficiencies on restorations

Individual occlusal contacts - Prematurities

Soft tissue contours

Subgingival calculus.

Site-level risk assessment

Site-level risk assessment would include:

Bleeding on probing

Exudation from periodontal pockets

Local root grooves or root concavities

Individual probing pocket depth

Attachment levels

Other anatomical factors like enamel pearls, root grooves.

The clinical practice of risk assessment

Most dentists and periodontists are not trained or experienced in risk assessment nor in using interventions aimed at risk reduction in the prevention and management of periodontal diseases. Manually summarizing and analyzing the risk factors could be a complex process. Hence, a computer-generated risk assessment model can aid in the identification of patients at elevated risk of developing periodontal disease, and may help in the selection of patients who require additional education or targeted interventions to prevent or minimize the impact of periodontal disease. Several models like the Oral Health Information Suite (OHIS), Periodontal Risk Calculator (PRC) and American Academy of Periodontology self-assessment tool have been used to assess risk.[25]

The oral health information suite

OHISä is an information system protected under the U.S. Patent #6,484,144. The system is comprised of a suite of related tools for major oral health conditions including caries, periodontal disease and oral cancer. OHIS is unique for clinical dentistry by virtue of quantifying the risk for future disease in addition to quantifying the current periodontal disease state. Both clinical and radiographic examinations are conducted including medical and dental histories, with specific questions concerning risk factors for oral disease. Diagnostic and demographic data and the patient and provider objectives are entered into the assessment tool appropriate for the disease state under consideration. A diagnosis is made and a risk score and a disease score are calculated. Based on these scores, treatment and interventions are ranked and color coded as those most likely to be successful, those less likely and those most unlikely to be successful. The recommended treatment plan is evaluated and modified by the dentist and patient to their satisfaction, and the treatments and interventions are performed. On re-examination following treatment, post-treatment risk and disease assessment are performed. Change in risk and disease state are automatically analyzed by the system and are used to update the risk and disease scores as well as to refine and improve the most appropriate treatments for any given set of conditions.[26]

Periodontal risk calculator

The PRC is a web-based tool that can be accessed through a dental office computer. PRC was developed using the six design parameters on a desktop computer using Microsoft Excel.

PRC calculated risk is for future periodontal disease for those patients who do not yet have it and risk for future progression of periodontal disease for those who already have it.

A risk factor is defined as a factor that is part of the causal chain of disease or exposes the patient to the casual chain, which, if present, directly increases the probability of disease occurring and, if absent, reduces the probability.

A risk factor must have a scientific basis that is supported by publication in refereed scientific journals.

The application of risk assessment information through the development of treatment recommendations to reduce risk must occur.

All requisite information must be obtained during a traditional periodontal examination as performed by dentists in the United States; the time required for data collection and input must fit within the usual time these dentists use for diagnosis.

A five-point risk scale is to be used to balance the sensitivity of risk assessment with the time and cost required to obtain the necessary information.

The calculation of risk is a multi-step process involving mathematical algorithms that use nine risk factors, including:

Patient age

Smoking history

Diagnosis of diabetes

History of periodontal surgery

Pocket depth

Furcation involvements

Restorations or calculus below the gingival margin

Radiographic bone height

Vertical bone lesions.

A three-point scale is used to document pocket depth and radiographic bone height. An algorithm was developed to quantify disease severity from pocket depth and bone height values. The base risk score is calculated using an algorithm that correlates disease severity with age. The risk score is increased if there is a positive history of periodontal surgery and if the patient smokes more than 10 cigarettes per day, or the patient has diabetes that is poorly controlled. The existence of furcation involvements, vertical bone lesions or subgingival restorations or calculus increase risk when the risk score is otherwise less than four.[27]

American academy of periodontology self-assessment tool

The web-based self-assessment tool available on the American Academy of Periodontology website is a good example of the value and limitations of how knowledge about the role of individual periodontal risk factors may be used in combination to educate patients, raise awareness and assist in decision-making. The tool's web interface is a brief 13-item questionnaire that asks straightforward questions that most persons would be able to answer easily. The items include the person's age (three response options: <40; 40-65; >65 years) and their flossing behavior (daily, weekly, seldom). Other items have simple response choices of yes or no, whereas several items in addition to the yes/no option also include the option of don′t know (any of your family members had gum disease, are your teeth loose, do you currently have any of the following health conditions, i.e. heart disease, osteoporosis, osteopenia, high stress or diabetes) or the option of don′t remember (seen a dentist in the last 2 years, ever been told that you have gum problems, gum infection or gum inflammation). The answers to the questions are combined using a proprietary algorithm to yield one of three risk categories: low risk, medium risk or high risk. The website informs users that by using the answers to the questions, the self-assessment tool will help them to see if they are at risk for having or developing periodontal (gum) disease.[28]

Genetic tests

Recently, a genetic test was available to test patients for periodontal disease risk. This test determines whether people possess a combination of alleles in two IL-1 genes.[16] Studies have reported an increased frequency of a different IL-1 genotype in people with advanced adult periodontitis compared with those with early or moderate disease. There is also retrospective evidence that genetic testing for the specific IL-1 genotype may give indication of increased susceptibility to tooth loss in periodontal maintenance patients. A more recent prospective study reported that this composite genotype was not associated with progressive clinical attachment loss during a 2-year period after periodontal therapy. However, it may be concluded that genetic testing has potential for the future, but more research is needed to evaluate its utility.[3]

CONCLUSION

Risk assessment is an important part of modern day periodontal practice. It is recommended that systemic and local risk factors are documented alongside the diagnosis in patients′ case records. The practice of risk assessment allows dental care professionals the opportunity to improve dental and medical outcomes in the general population and in specific population groups by focusing on early identification and prevention of dental diseases, especially periodontal disease.

The inclusion of a risk assessment tool in routine practice would add only a small amount of time to patient visits. Signs and symptoms targeted in risk assessment might include pocket depth, bleeding on probing, poor oral hygiene, persistent inflammation, loss of attachment, smoking, increasing pocket depth, pregnancy and diabetes. Among the general public, use of a risk assessment instrument may help identify the 20% of patients in need of intervention to prevent or minimize development of more advanced periodontal disease.