Evaluating the validity of probing attachment loss as a surrogate for tooth mortality in a clinical trial on the elderly

Outcomes of periodontal therapy: Strengthening the relevance of research to patients. A co-created review

Periodontitis is a long-term condition affecting up to half of the population globally and causing significant impacts on life quality. Successful management depends on taking life-long ownership of the condition by those affected. There is a wealth of research to inform on management options. However, most of the research has been designed by professional experts with outcomes to gauge benefits and harms based on parameters that inform on the disease process but which might not be informative to support decision-making in people with lived experience (PWLE) of periodontal ill-health (including both patients and carers). The importance of relevant outcomes is highlighted in the concept of the "expert patient" which aims to strengthen the capacity of PWLE to make health-care choices that are important for them, elements of which are likely to be already familiar to many clinicians delivering periodontal health care. Therefore, the voice and collaboration of PWLE in research are recognised as crucial to developing high quality, relevant evidence especially for long-term conditions. In this paper, we review what is known about the relevance of treatment outcomes to PWLE. We also examine the degree to which PWLE have been involved in identifying outcomes that are important to them as well as the diversity and therefore representativeness of PWLE recruited for studies. We consider why having more relevant outcomes could enhance the expertise of PWLE in managing their periodontitis. We then conclude with key learnings from our review which we hope will encourage more rapid development of these initiatives in periodontology for the benefit of global health and wellbeing.

Influence of Periodontal Disease on QoL of Periodontal Patients in Riyadh

Aims and objectives:

The aim of this study was to assess the influence of periodontal status on quality of life (QoL) with the use of a short version of the Oral Health Impact Profile (OHIP-14) in patients with periodontal disease attending university in Riyadh, Saudi Arabia.

Materials and methods:

Adult patients diagnosed with periodontal disease and having minimum of 15 teeth or more present was included. Included patients were requested to fill a questionnaire form and undergo a comprehensive clinical periodontal examination. The influence of oral health on patients’ QoL was assessed using the Arabic version of OHIP-14.

Results:

A total of 25 adults aged between 23 and 80 years with a mean age of 49 years completed the questionnaire. The impact of periodontal disease on patient’s QoL was statistically significant in 2 domains, namely physical pain ( P = .004) and psychological disability ( P = .001). The severity of periodontal disease did not show a negative impact on functional limitation. In general, the total OHIP-14 scores were statistically significant with the number of teeth with pocket depths of 5 mm ( P = .001) and 7 mm ( P = .011).

Conclusions:

Periodontal destruction has a negative impact on QoL. The use of this index as well as other patient-centered outcome measures has significant implications in periodontology, including treatment planning and evaluation of treatment results.

Patients' preferences in periodontal disease treatment elicited alongside an IQWiG benefit assessment: a feasibility study

BACKGROUND AND PURPOSE

The German Institute for Quality and Efficiency in Health Care (IQWiG) previously tested two preference elicitation methods in pilot projects and regarded them as generally feasible for prioritizing outcome-specific results of benefit assessment. The present study aimed to investigate the feasibility of completing a discrete choice experiment (DCE) within 3 months and to determine the relative importance of attributes of periodontal disease and its treatment.

PATIENTS AND METHODS

This preference elicitation was conducted alongside the IQWiG benefit assessment of systematic treatments of periodontal diseases. Attributes were defined based on the benefit assessment, literature review, and patients' and periodontologists' interviews. The DCE survey was completed by patients with a history of periodontal disease. Preferences were elicited for the attributes "tooth loss within next 10 years", "own costs for treatment, follow-up visits, re-treatment", "complaints and symptoms", and "frequency of follow-up visits". Patients completed a self-administered questionnaire including 12 choice tasks. Data were analyzed using a random parameters logit model. The relative attribute importance was calculated based on level ranges.

RESULTS

Within 3 months, survey development, data collection among 267 patients, data analysis, and provision of a study report could be completed. The analysis showed that tooth loss (score 0.73) was the most important attribute in patients' decisions, followed by complaints and symptoms (0.22), frequency of follow-up visits (0.02), and costs (0.03) (relative importance scores summing up to 1).

CONCLUSION

A preference analysis performing a DCE can be generally feasible within 3 months; however, a good research infrastructure and access to patients is required. Outcomes used in benefit assessments might need to be adapted to be used in preference analyses.

Patient Centered Outcomes in Periodontal Treatment-An Evidenced Based Approach

Transformation of research into clinical practice is the most challenging step in evidence based dental practice. Designing the most reliable research with applicable endpoint evaluation is very important as it can lead to successful research outcomes that can be accepted in clinical practice. In the periodontal research few accepted endpoints are used frequently as they are believed to be the gold standard in measuring the periodontal disease and the treatment outcomes. However, a wide range of endpoints used are surrogate endpoints and these endpoints have no direct correlation with the patient centered outcomes. Hence, a direct relationship of surrogate endpoints with true endpoints needs to be established. This review highlights the importance of true endpoints and challenges in implementing these in clinical research. Importance of patient's centered outcomes are also reviewed and duly discussed here. Need for conducting research which includes the true endpoints or the surrogate endpoints with clinical applicability and tangible outcomes, was also suggested in this review.

Systematic Review and Meta-analysis of the Association Between Exposure to Environmental Tobacco Smoke and Periodontitis Endpoints Among Nonsmokers

OBJECTIVE

A systematic review was conducted to summarize the epidemiological evidence on environmental tobacco smoke (ETS) exposure and prevalent periodontitis endpoints among nonsmokers.

METHODS

We searched PubMed, EMBASE, Web of Science, Pro-Quest dissertations, and conference proceedings of a dental research association. We included studies from which prevalence odds ratios (POR) could be extracted for periodontitis determined by examiner measurements of clinical attachment level (CAL) and/or probing pocket depth (PD) or self-report of missing teeth. Studies determined ETS exposure by self-report or biomarker (cotinine) levels.

RESULTS

For studies reporting CAL and/or PD (n = 6), associations were stronger with cotinine-measured exposure (n = 3; random effects POR [95% prediction interval] = 1.63 (0.90, 2.96)) than self-reported exposure (n = 3; random effects POR = 1.15 (0.68, 1.96)). There was no meaningful difference in summary estimate for studies reporting CAL and/or PD endpoint (n = 6; random effects POR = 1.34 (0.93, 1.94)) as opposed to tooth loss (n = 2; random effects POR = 1.33 (0.52, 3.40)).

CONCLUSIONS

There appears to be a positive association between exposure to ETS and prevalent periodontitis endpoints among nonsmokers, the magnitude of which depended mostly on the method of ETS assessment.

IMPLICATIONS

The notoriety of ETS is often discussed in terms of its associations with cancer, chronic conditions like cardiovascular diseases, and respiratory illnesses in children. However, very little attention is paid to its association with oral diseases, especially periodontitis. Periodontitis affects a large proportion of the population and is a major cause of tooth loss. This study summarized the epidemiologic association between exposure to ETS and periodontitis among nonsmokers. Although the findings are consistent with a positive association, methodological weaknesses relating to study design, assessment of ETS, periodontitis, and adjustment covariates were highlighted and recommendations for improvement in future studies provided.

Chlorhexidine and Preservation of Sound Tooth Structure in Older Adults

The Trial to Enhance Elderly Teeth Health (TEETH) was designed to test the impact of regular rinsing with a 0.12% chlorhexidine (CHX) solution on tooth loss, and the causes of tooth loss (caries, periodontal disease and trauma) were also investigated. This paper reports on the effectiveness of a 0.12% CHX solution for controlling caries using a tooth surface (coronal and root) survival analysis. A total of 1,101 low income elders in Seattle (United States) and Vancouver (Canada), aged 60-75 years, were recruited for a double-blind clinical trial and assigned to either a CHX (n = 550) or a placebo (n = 551) mouth rinse. Subjects alternated between daily rinsing for 1 month, followed by weekly rinsing for 5 months. All sound coronal and root surfaces at baseline were followed annually for up to 5 years. At each follow-up examination, those tooth surfaces with caries, restored, or extracted were scored as 'carious'. The hazard ratio associated with CHX for a sound surface to become filled, decayed, or extracted was 0.87 for coronal surfaces (95% confidence interval: 0.71-1.14, p = 0.20) and 0.91 for root surfaces (95% confidence interval: 0.73-1.14, p = 0.41). These findings suggest that regular rinsing with CHX does not have a substantial effect on the preservation of sound tooth structure in older adults.

Oral health-related quality of life and periodontal status

BACKGROUND

As patient-centered approaches become more popular, increasing attention is being given to assess the effects of various human health situations on an individual's overall quality of life (QoL). Measures have been used in dentistry to study the effects of orthodontic treatment and oral surgery, but so far little has been reported about the effects of periodontal disease.

OBJECTIVE

This study assessed the impact of periodontal health status on QoL.

METHODS

A subsample of 767 subjects were selected from a community study (n=1000) which investigated the association between psychological factors and clinical periodontal attachment level (CAL). The sample included subjects with full-mouth mean CAL<or=2 mm (healthy/low periodontal attachment loss group), and subjects with full-mouth mean CAL>3 mm (high/severe periodontal attachment loss group). The subjects were requested to complete the Chinese short-form version of Oral Health Impact Profile (OHIP-14S) and a checklist of self-reported periodontal symptoms during the previous 12 months.

RESULTS

A total of 727 subjects (95%) completed the questionnaire. The OHIP-14S and subscale scores were significantly associated with six of seven of the self-reported periodontal symptoms. A comparison of the mean OHIP-14S scores of the healthy/low and the high/severe periodontal attachment loss groups revealed significant differences in respect of the subscales of functional limitation, physical pain, psychological discomfort, physical and psychological disabilities.

CONCLUSION

This study demonstrates a significant association between oral health-related QoL and periodontal disease.

Validation of self-reported periodontal disease: a systematic review

Self-report is an efficient and accepted means of assessing many population characteristics, risk factors, and diseases, but has rarely been used for periodontal disease (chronic periodontitis). The availability of valid self-reported measures of periodontal disease would facilitate epidemiologic studies on a much larger scale, allow for integration of new studies of periodontal disease within large ongoing studies, and facilitate lower-cost population surveillance of periodontitis. Several studies have been conducted to validate self-reported measures for periodontal disease, but results have been inconsistent. In this report, we conducted a systematic review of the validation studies. We reviewed the 16 studies that assessed the validity of self-reported periodontal and gingivitis measures against clinical gold standards. Seven of the studies included self-reported measures specific to gingivitis, four included measures only for periodontitis, and five included both gingivitis and periodontal measures. Three of the studies used a self-assessment method where they provided the patient with a detailed manual for performing a self-exam. The remaining 13 studies asked participants to self-report symptoms, presence of periodontal disease itself, or their recollection of a dental health professional diagnosing them or providing treatment for periodontal disease. The review indicates that some measures showed promise, but results varied across populations and self-reported measures. One example of a good measure is, "Has any dentist/hygienist told you that you have deep pockets?", which had a sensitivity of 55%, a specificity of 90%, positive predictive value of 77%, and negative predictive value of 75% against clinical pocket depth. Higher validity could be potentially obtained by the use of combinations of several self-reported questions and other predictors of periodontal disease.

The use of surrogate variables to reflect long-term tooth survivability

Clinical parameters used to monitor periodontal patients are usually measures of the disease process. They are considered surrogate variables because changes in their status are interpreted to have an impact on the ultimate goal of periodontal therapy, which is tooth retention. However, their ability to reflect tooth survivability has been questioned because there is a lack of long-term data to validate that stable or improved surrogates result in reduced tooth loss. Therefore, to clarify the utility of employing surrogates to reflect long-term tooth retention, a number of issues related to their use are discussed in this commentary: phraseology, benefits and shortcomings, biologic credibility, and their previous successful utilization in monitoring the effects of therapy. This commentary supports the reasonableness of using surrogates to monitor periodontal status and suggests that a combination of surrogates that represent "periodontal clinical health" should be considered a true endpoint of periodontal therapy, since this outcome provides a condition conducive to tooth retention.

The elderly at risk for periodontitis and systemic diseases

The increasing population of older subjects with dental care needs will become a major challenge to our society and its care providers. To manage the health care needs of the elderly, a coordination between medical and dental care providers will become necessary. From the dental perspective, it is important to develop skills in the risk assessment of older patients. Such risk assessment of older subjects should take an approach that is holistic and focused on the reduction of the infectious burden and the improvement of self-efficacy.

Root Canal Treatment in a Population-Based Adult Sample: Status of Teeth After Endodontic Treatment

The purpose of this study was to quantify treatment outcomes of endodontically treated teeth, in a representative, population-based adult sample. The "Florida Dental Care Study" was a prospective, longitudinal, cohort study of 873 subjects who had at least one tooth at baseline and who were 45 yr or older. An in-person interview and clinical examination were conducted at baseline, 24 months, and 48 months after baseline, with 6-monthly telephone interviews between those times. Dental record information was abstracted afterward. Seventy-five teeth had conventional root-canal therapy (RCT) performed and met the inclusion criteria of 1-yr of follow-up or extraction. The mean duration of follow-up after RCT was 24.8 months. The mean (SD) attachment loss (AL) on teeth receiving RCT was only 3.3 (1.4) mm. Permanent restorations were placed in 79% of teeth a mean of 4.4 months after the RCT. However, 12% of teeth did not have any restorative treatment after RCT. After RCT had been completed, 81% of teeth were retained and 19% were ultimately extracted. Taken as a whole, this community-based study of a representative sample of adults suggests a higher failure rate than reported from studies in highly controlled environments or insured populations. It also suggests that the length of time to initial restoration of RCT-treated teeth is less than optimal. RCT was almost never performed on teeth with advanced periodontal attachment loss.

Impact of oral health on the life quality of periodontal patients

OBJECTIVES

To assess the impact of oral health on the life quality of a periodontal patient group.

MATERIALS AND METHODS

Two hundred and five patients attending a private periodontal clinic completed a questionnaire incorporating the 16-item UK oral health-related quality-of-life measure (OHQoL-UK), a check list of questions about their periodontal health over the past year and a comprehensive periodontal examination.

RESULTS

The effect of oral health on quality of life was considerable, with many individuals experiencing negative impacts across a broad range of physical, social and psychological aspects of life quality. OHQoL-UK(Copyright ) scores was associated with patient's self-reported periodontal health in the past year: experiences of "swollen gums" (p<0.01), "sore gums" (p<0.01), "receding gums" (p<0.01), "loose teeth" (p<0.01), "drifting teeth" (p<0.01), "bad breath" (p<0.01) and "toothache" (p<0.01). In addition, OHQoL-UK scores were correlated with the number of teeth with pocket depths of 5 mm or more (r(s)-0.42, p<0.01). New patients had poorer oral health-related quality of life compared with the treated maintenance group (p<0.01).

CONCLUSIONS

Periodontal status impacts on life quality. This has implications in understanding the consequences of periodontal health and in the use of patient-centred outcomes in periodontal research.

Analysis of periodontal risk profiles in adults with or without a history of myocardial infarction

BACKGROUND

An association between periodontitis and cardiovascular diseases has been suggested.

AIMS

To study whether a combination of clinical variables in a functional risk diagram enhanced the ability to differentiate between subjects with or without an immediate history of acute myocardial infarction (AMI).

MATERIAL AND METHODS

A functional periodontal pentagon risk diagram (PPRD) with five periodontal risk vectors was created. The surface of individual PPRDs was calculated using data from 88 subjects with recent AMI and 80 matched control subjects with no history of AMI.

RESULTS

Age, gender, number of remaining teeth (mean value: 21.1 versus 21.6 teeth), smoking status, and pocket probing depth (PPD) distribution did not differ by group. Gingival recession was greater in control subjects (mean difference: 5.7, SD: +/- 1.9, p<0.01, 95% CI: 1.8-9.6). Bone loss > or = 4.0 mm was at all levels studied was significantly greater in subjects with AMI and bone loss > or = 50% (> or = 4 mm) was the best individual predictor of AMI (beta = 2.99, p < 0.000, 95% CI: 7.5-53.4). Only PPRD scores were associated with AMI status when factors not included in the PPRD were studied (beta = 22.1, SE: 5.9, p < 0.0001, 95% CI: 10.3-33.7). The best association between AMI status and study variables was the combination of > or = 4 mm of bone loss > or = 50%, proportion of bleeding on probing (%BOP), %PPDs > or = 6 mm, and tooth loss (Nagelkirke r2 = 0.46).

CONCLUSIONS

The combination of five periodontal parameters in a PPRD added predictive value, suggesting that comprehensive data should be used in studies of associations between periodontitis and heart diseases. Radiographic evidence of bone loss was the best individual parameter.

Patient-based assessments of clinical periodontal conditions in relation to alveolar bone loss

BACKGROUND

Limited subject-based information exists on the relationship between clinical and radiographic periodontal data.

AIMS

To use subject-based data to assess the extent of concurrence between clinical and radiographic information, and to study what clinical information best predicts alveolar bone loss (ABL).

MATERIAL AND METHODS

Subject-based data on smoking habits, bleeding on probing, plaque scores, pocket probing depth (PD), and evidence of alveolar BL were obtained, and functional periodontal pentagon risk diagrams (PPRDs) were studied from 168 consecutive subjects attending a medical clinic.

RESULTS

The mean age of the subjects was 62.7 years (SD+/-9.0). The average number of teeth was 21.3 (SD+/-8.0) with on average 5.6 molars remaining (SD+/- 3.9). In this subject cohort, 33.1% had never smoked, 44.2% had quit smoking, and 22.7% were currently smokers. Mean plaque and bleeding scores were high or 60.2% (SD+/-24.0) and 53.1% (SD+/-23.6), respectively. PDs >or=6.0 mm were found in 55.9% of the subjects. Binary logistic regression analysis demonstrated that tooth loss and proportional plaque scores were the predominant factors included in the equations associated with ABL. Wald coefficients varied between 3.99 and 9.15, and with p-values between 0.05 and 0.01. When included, the PPRD score became the exclusive factor at several cut-off levels (Wald's coefficients between 19.8 and 15.6, p<0.001). Consequently, the best receiver operator curve was identified for the PPRD at the >40% cut-off ABL level (area under the curve: 0.81; 95% CI: 0.74-0.89; p<0.001).

CONCLUSIONS

The number of teeth lost and the proportion of plaque scores provided significant predictive factors for ABL. The functional PPRD demonstrated an exclusive and highly predictable association with ABL. Subject-based proportional data for PDs >4.0 mm provided poor substitute measures for the extent of ABL.

Predicting tooth loss during a population-based study: role of attachment level in the presence of other dental conditions

BACKGROUND

Our objectives were to quantify: 1) the association between incident tooth loss and prior periodontal attachment level; and 2) the contribution to tooth loss made by non-periodontal conditions in increasingly periodontally involved teeth.

METHODS

The Florida Dental Care Study was a prospective cohort study of persons who at baseline had at least 1 tooth and were 45 years or older. In-person interviews and clinical examinations were conducted at baseline, and at 24 and 48 months, with telephone interviews at 6-month intervals in between. A regression model was used to simultaneously quantify tooth-specific predictors of tooth loss, with person-level factors taken into account.

RESULTS

Of the 687 persons who participated for a 48-month clinical examination, 36% lost 1 or more teeth during follow-up, and 5.0% of all teeth were lost. Attachment level up to 2 years before tooth loss was strongly predictive of incident tooth loss, with increases in risk for each millimeter in attachment loss. Certain other tooth-specific conditions (tooth mobility, bulk restoration fracture, decayed surfaces, filled surfaces, tooth type and arch location, root fragment) were strongly and independently associated with increased risk for tooth loss, while others were not (prosthetic crown coverage, cusp fracture, root surface defect). Propensity to choose extraction over other treatment alternatives, as reported by participants at baseline, was also strongly predictive of tooth loss.

CONCLUSIONS

Increasingly severe attachment level was consistently associated with an increased risk for tooth loss in this sociodemographically diverse sample, with or without other tooth-specific conditions taken into account.

A systematic review of guided tissue regeneration for periodontal infrabony defects

OBJECTIVES

To systematically review the evidence for efficacy of guided tissue regeneration (GTR) for infrabony defects.

BACKGROUND

The evidence for the efficacy of GTR has not yet been systematically appraised.

METHODS

We searched for randomised controlled trials of at least 12 months' follow-up comparing GTR with open flap debridement (OFD). Data sources included electronic databases, hand-searched journals and contact with experts. Screening, data abstraction and quality assessment were conducted independently by multiple reviewers. The primary outcome measure was gain in clinical attachment.

RESULTS

For attachment level change, the weighted mean difference between GTR alone and open flap debridement was 1.11 mm (95% CI: 0.63-1.59), chi-square for heterogeneity 31.4 (9 df ), P < 0.001) and for GTR + bone substitutes was 1.25 mm (95% CI: 0.89-1.61, chi-square for heterogeneity 0.01 (1 df), P = 0.91). The number of sites needed to treat (NNT) for GTR to achieve one extra site gaining 2 mm or more attachment over open flap debridement was 8 (95% CI: 4-33). Heterogeneity between studies was highly statistically significant for all principal comparisons and could not be explained satisfactorily by sensitivity analyses.

CONCLUSIONS

Overall, GTR was more effective than OFD in improving attachment levels. However, there was marked variability between studies and general conclusions about the clinical benefit of GTR are limited by this heterogeneity. Future studies should aim to identify factors associated with achieving consistent benefits over open flap debridement. Open flap surgery should remain the control comparison in these studies.

Bayesian estimation of the proportion of treatment effect captured by a surrogate marker

Surrogate endpoints in clinical trials are biological markers or events observable earlier than the clinical endpoints (such as death) that are actually of primary interest. The "proportion of treatment effect captured" by a surrogate endpoint (PTE) is a frequentist measure intended to address the question of whether trials based on a surrogate endpoint reach the same conclusions as would have been reached using the true endpoint. The question of inferential interest is whether PTE for a given marker exceeds some threshold value, say 0.5. Calculating PTE requires fitting two different models to the same data. We develop a Markov chain Monte Carlo based method for estimating the Bayesian posterior distribution of PTE. The new method conditions on the truth of a single model. Obtaining the full posterior distribution enables direct statements such as "the posterior probability that PTE >0.5 is 0.085". Furthermore, credible sets do not depend on asymptotic approximations and can be computed using data sets for which the frequentist methods may be inaccurate or even impossible to apply. We illustrate with Bayesian proportional hazards models for clinical trial data. As a by-product of developing the Bayesian method, we show that the frequentist estimate of PTE also may be computed from quantities in a single model and calculate frequentist confidence intervals for PTE that tend to be narrower than those produced by standard methods but that provide equally good coverage.

The antimicrobial treatment of periodontal disease: changing the treatment paradigm

Over the last 100 years, methods of surgical periodontal treatment have enjoyed a history of success in improving oral health. The paradigm of care is based on the "non-specific plaque hypothesis"--that is, the overgrowth of bacterial plaques cause periodontal disease, and the suppression of this overgrowth reduces disease risk. The central feature of this approach to care is the removal of inflamed gingival tissue around the teeth to reduce periodontal pocket depth, thereby facilitating plaque removal by the dentist and by the patient at home. Over the last 30 years, with the recognition that periodontal disease(s) is caused by specific bacteria and that specific antimicrobial agents can reduce or eliminate the infection, a second paradigm has developed. This new paradigm, the "specific plaque hypothesis", focuses on reducing the specific bacteria that cause periodontal attachment loss. The contrast between the two paradigms can be succinctly stated as follows: The antimicrobial therapy reduces the cause, while the surgical therapy reduces the result of the periodontal infection. The specific plaque hypothesis has two important implications. First, with the increasing attention to evidence-based models for prevention, treatment, outcome assessment, and reimbursement of care, increasing attention and financial effort will be channeled into effective preventive and treatment methods. Second, the recent observations that periodontal infections increase the risk of specific systemic health problems, such as cardiovascular disease, argue for the prevention and elimination of these periodontal infections. This review highlights some of the evidence for the specific plaque hypothesis, and the questions that should be addressed if antimicrobial agents are to be used responsively and effectively.

An index of clinical oral disorder in elders (CODE)

Attempts to construct an index of oral health or disorder suitable for older adults have been limited in clinical scope or based on the judgement of very few individuals. Consequently, we present here a multidimensional index of Clinical Oral Disorder in Elders (CODE) based on a breadth of clinical measures relevant to elders. The data for the index are derived from a clinical examination of jaw function, dentures, mucosa, teeth, and periodontium. Weighting or ranking for each disorder within the context of an elderly person was established as mild, moderate or severe by experienced dental clinicians and dental hygienists. Subsequently, the index was constructed by transforming the weights into a numerical value for each clinical measure. Individual scores can relate to the heaviest weight identified during the examination or to the sum of the weights assigned throughout the examination, and the average score during a series of examinations will reflect the clinical status of a particular population. Clinical applications in elderly residential-care populations indicate that the index can be constructed efficiently and with reasonable reliability. We suggest, therefore, that the CODE index is suitable for descriptive and comparative research by providing a clinical format for measuring oral disorder in disabled elders, and, when combined with a psychosocial index, it should be very comprehensive indicator of oral dysfunction in older adults.

The informativeness of attachment loss on tooth mortality

BACKGROUND

In periodontal clinical trials, clinical attachment level measurements are commonly used as surrogates for tooth loss. Conclusions regarding treatment efficacy in these trials are valid if: 1) the surrogate is informative on tooth loss, and 2) the surrogate captures the effect of treatment on tooth loss. The goal of this study was to evaluate the first criterion: Are serial clinical attachment loss measurements informative on overall tooth mortality?

METHODS

Young Norwegian men (aged 17 to 35) were first examined in 1969 (n=565) and followed for 26 years with examinations in 1971 (n=381), 1973 (n=292), 1975 (n=245), 1981 (n=228), 1988 (n=202), and 1995 (n=223). Several aspects of the serial attachment loss measurements were related to tooth mortality risk using statistical models that take into account the time-dependent changes of the clinical attachment loss measurements.

RESULTS

The results provided evidence that moderate attachment losses were informative on tooth mortality. Both the lifetime cumulative attachment loss, as well as attachment loss since young adulthood, of > or = 2 mm or > or = 3 mm was informative on tooth mortality. Tooth mortality risk increased as the attachment loss increased; loss > or = 3 mm at the buccal or mesial site increased tooth mortality risk, by 91% (relative risk, 1.91; 95% confidence interval, 1.01-3.60) and 270% (RR, 3.70; 95% CI, 1.83-7.49), respectively.

CONCLUSIONS

We concluded that clinical attachment loss was moderately informative on overall tooth mortality in this Norwegian population. Since this finding has now been demonstrated in 3 different populations, the focus of further research should be on evaluating whether the second criterion for a valid surrogate is satisfied: Does clinical attachment loss capture the effect of periodontal treatments on tooth loss?

Evaluating the burst hypothesis at a site-specific level using the lack-of-fit test

It has been hypothesized that periodontal disease progresses by means of sudden losses of periodontal attachment surface area. Obtaining reliable tests of this burst hypothesis has proven to be difficult; the signal (true model of disease progression) often gets lost in the noise. The purpose of this study was to determine how reliably we could distinguish sudden changes from linear disease progression at a site using a time series of clinical attachment levels. Specifically, the following question was investigated: If, in reality, disease progresses by means of sudden changes in clinical attachment level (bursts), and a linear model is fitted to these data, what is the likelihood of rejecting the linear model using the lack-of-fit test? This likelihood was determined as a function of the probing measurement error (range: 0.2 to 1.0 mm) and the number of clinical examinations over time. The results suggested that bursts of 2 mm or smaller cannot be reliably distinguished from linear disease progression using the lack-of-fit test, except under unusual clinical circumstances. Under typical clinical circumstances, burst sizes needed to be 3 to 5 mm in order to be reliably distinguished from linear disease progression. These results are probably overly optimistic. The ability to verify the burst hypothesis at the site level is likely to be even less than our results indicate because of various assumptions that were required. We conclude that the lack-of-fit test will reliably reject the linear model at a site-specific level only if true disease progresses in such a fashion that a handful of sudden changes leads to a tooth mortality event.

The effects of simple interventions on tooth mortality: findings in one trial and implications for future studies

The purpose of this report was to use a particular clinical trial, the Preventive Geriatric Trial (PGT), as a starting point to discuss whether treatment efficacy can be evaluated by means of tooth mortality. In the PGT, 296 subjects were recruited and randomly assigned to five treatment groups: (1) usual procedures (UP); (2) UP + a cognitive-behavioral intervention (CB); (3) UP + CB + weekly chlorhexidine rinse (CHX); (4) UP + CB + CHX + semi-annual fluoride varnish (F); and (5) UP + CB + CHX + F + semi-annual prophylaxis, including scaling (P). Exploratory analyses revealed that tooth mortality after the 1st year was lower in treatment groups 3, 4, and 5 than in groups 1 and 2. A one-year exposure resulted in a 45% reduction in tooth mortality (p < 0.05); a two-year exposure resulted in a 59% reduction (p-value < 0.04). The PGT findings suggested that it is possible to design trials based on clinically relevant endpoints, such as tooth mortality. For the detection of moderate treatment effects, such trials could take the form of Large, Simple Trials (LST), where many subjects are recruited with minimally restrictive entry criteria, and data are collected only on essential baseline characteristics and tooth mortality. LSTs have provided "reliable answers to important clinical questions" for other chronic diseases, and several arguments suggest that they could play a similar critical role in dental research: (1) Periodontitis and caries are among the most common and costly chronic diseases affecting humans, and the identification of even moderately effective treatments by LSTs can have a large socio-economic impact; (2) the identification of low-cost widely practicable treatments that lend themselves to be investigated in LSTs is likely to benefit more people than the identification of high-cost complex treatments; and (3) tooth mortality is simple to assess and more relevant than the unvalidated surrogate endpoints that have largely failed for more than 20 years to provide reliable answers to certain controversial issues regarding treatment efficacy. The cost of not reliably establishing the safety and the efficacy of treatments may be far greater than the cost of conducting LSTs.