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T A DeRouen

Publications and source records attributed to T A DeRouen.

At least 19 recordsLinked to original sources
PubMed2004

Efficiency issues among statistical methods for demonstrating efficacy of caries prevention.

Although repeated tooth-surface-specific information is commonly collected during a longitudinal caries clinical trial, traditional methods often make limited use of the repeated measures. Newer methods of analysis, such as methods based on time-to-event and methods for longitudinal or clustered data, have the potential to increase the efficiency of the statistical analysis. We compare a range of analytical methods from the traditional analysis based only on the number of caries onsets to newer methods that incorporate time at risk and surface-specific information, such as Poisson regression methods for clustered data, with respect to the efficiency of treatment comparisons. Under most circumstances, the greatest gain in efficiency associated with time-to-event methods will be due to the ability of subjects to contribute caries onsets to the analysis until they are lost from the study. Incorporating the number of surfaces at risk, the surface time at risk, and surface-specific characteristics will typically produce only a modest gain in efficiency.

Clinical Trials as Topic↗
PubMed2003

A hidden periodontitis epidemic during the 20th century?

OBJECTIVES: Increasing evidence suggests a strong causal link between smoking and periodontitis. The goal of this study was to impute how the secular changes in smoking prevalence during the 20th century impacted the advanced periodontitis incidence in the US. METHODS: Epidemiological analyses based on US prevalence data of advanced periodontitis and smoking, and predictions of future smoking prevalence. RESULTS: Assuming other risk factors for periodontitis remained constant, we estimated that the incidence of advanced periodontitis decreased by 31% between 1955 and 2000. The changes in smoking habits, and consequently the changes in periodontitis incidence, depended strongly on education and gender. Between 1966 and 1998, we estimated a 43% decreased periodontitis incidence among college-educated individuals versus only an 8% decrease among individuals with less than a high school education. Between 1955 and 1999, we estimated a 41% decrease among males versus a 14% decrease among females. By the year 2020, the incidence of advanced periodontitis may decrease 43% from its level in 1955. CONCLUSIONS: A periodontitis epidemic fueled by smoking remained hidden for most of the 20th century. Because this epidemic was hidden, it distorted our understanding of the treatment and etiology of periodontitis. The socioeconomic polarization of this epidemic will dictate alterations in patterns of periodontal care.

Adult↗
PubMed2003

Bias induced by self-reported smoking on periodontitis-systemic disease associations.

Non-causal associations between periodontitis and systemic diseases may be spuriously induced by smoking because of its strong relationship to both. The goal of this study was to evaluate whether adjustment for self-reported smoking removes tobacco-related confounding and eliminated such spurious confounding. Using NHANES III data, we evaluated associations between attachment loss and serum cotinine after adjustment by self-reported number of cigarettes smoked. Cotinine, a metabolite of nicotine, should not be related to attachment loss, if self-reported smoking captures the effect of tobacco on attachment levels. Adjustment for self-reported cigarette smoking did not completely remove the correlation between attachment loss and serum-cotinine level (r = 0.075, n= 1507, p = 0.003). Simulation studies indicated similar results for time-to-event data. These findings demonstrate the difficulty in distinguishing the effects of periodontitis from those of smoking with respect to a smoking-related outcome. Future studies should report results of analyses on separate subcohorts of never-smokers and smokers.

Bias↗
PubMed2002

Pre-existing cardiovascular disease and periodontitis: a follow-up study.

Periodontal infections in individuals with pre-existing heart disease are believed to increase the risk for future coronary heart disease (CHD) events. The goal of this study was to search for an association between periodontitis and CHD events among individuals with pre-existing heart disease, reported in the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study. Dentate adults (n = 636) with a history of pre-existing cardiovascular disease were followed for CHD events. The presence of periodontitis and gingivitis did not increase CHD risk among these at-risk individuals (hazard ratio [HR], 0.97, and 95% confidence interval [CI], 0.72-1.31; and HR, 1.09, and 95% CI, 0.79-1.50, respectively). When limited to individuals with a self-reported prior heart attack, periodontitis was associated with a 34% decreased CHD risk (HR, 0.66; 95% CI, 0.42-1.05). It is concluded that periodontitis or gingivitis does not elevate CHD risk among individuals with a prior heart attack or self-reported pre-existing cardiovascular disease.

Adult↗
PubMed2001

A covariance estimator for GEE with improved small-sample properties.

In this paper, we propose an alternative covariance estimator to the robust covariance estimator of generalized estimating equations (GEE). Hypothesis tests using the robust covariance estimator can have inflated size when the number of independent clusters is small. Resampling methods, such as the jackknife and bootstrap, have been suggested for covariance estimation when the number of clusters is small. A drawback of the resampling methods when the response is binary is that the methods can break down when the number of subjects is small due to zero or near-zero cell counts caused by resampling. We propose a bias-corrected covariance estimator that avoids this problem. In a small simulation study, we compare the bias-corrected covariance estimator to the robust and jackknife covariance estimators for binary responses for situations involving 10-40 subjects with equal and unequal cluster sizes of 16-64 observations. The bias-corrected covariance estimator gave tests with sizes close to the nominal level even when the number of subjects was 10 and cluster sizes were unequal, whereas the robust and jackknife covariance estimators gave tests with sizes that could be 2-3 times the nominal level. The methods are illustrated using data from a randomized clinical trial on treatment for bone loss in subjects with periodontal disease.

Alveolar Bone Loss↗
PubMed2000

Periodontal disease and coronary heart disease risk.

CONTEXT: Research has suggested a relationship between periodontal disease and coronary heart disease (CHD), but data on the association between these 2 common conditions are inconclusive due to the possibility of confounding. OBJECTIVE: To evaluate the risk of CHD in persons with periodontitis, gingivitis, or no periodontal disease. DESIGN: Prospective cohort study. SETTING: The First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study, conducted in 1982-1984, 1986, 1987, and 1992. PARTICIPANTS: A total of 8032 dentate adults aged 25 to 74 years with no reported history of cardiovascular disease, including 1859 individuals with periodontitis, 2421 with gingivitis, and 3752 with healthy periodontal tissues. MAIN OUTCOME MEASURE: First occurrence of death from CHD or hospitalization due to CHD, or revascularization procedures, obtained from death certificates and medical records, by baseline periodontal status. RESULTS: During follow-up, 1265 individuals had at least 1 CHD event, including CHD fatality (n = 468) or at least 1 hospitalization with a diagnosis of CHD (n = 1022), including coronary revascularization procedures (n = 155). After adjustment for known cardiovascular risk factors, gingivitis was not associated with CHD (hazard ratio, 1.05; 95% confidence interval, 0.88-1.26), while periodontitis was associated with a nonsignificant increased risk for CHD event (hazard ratio, 1. 14; 95% confidence interval, 0.96-1.36). CONCLUSION: This study did not find convincing evidence of a causal association between periodontal disease and CHD risk. JAMA. 2000;284:1406-1410.

Adult↗
PubMed2000

Between-subject and within-subject statistical information in dental research.

The evaluation of risk factors in dental research frequently uses observations at multiple sites in the same patient. For this reason, statistical methods that accommodate correlated data are generally used to assess the significance of the risk factors (e.g., generalized estimating equations, generalized linear mixed models). In applications of these methods, it is typically assumed (implicitly, if not explicitly) that between-subject and within-subject comparisons will produce the same estimated effect of the risk factor. When between- and within-subject comparisons conflict, the statistical methods can give biased estimates or results that are difficult to interpret. For illustration, we present two examples from periodontal disease studies in which different statistical methods give different estimates and significance levels for a risk factor. Statistical analyses in dental research should assess whether different sources of information give similar conclusions about risk factors or treatments.

Confounding Factors, Epidemiologic↗
PubMed1998

Association of oral spirochetes from periodontally healthy sites with development of gingivitis.

The purpose of this investigation was to determine whether the presence of selected disease-associated bacteria in health-associated plaque correlated with future gingivitis. Sites of periodontal health were identified in 65 adults. Six months later (recall 1) plaque was collected from sites that remained in periodontal health, and 5 species of specific bacteria and pathogen-related oral spirochetes were detected using monoclonal antibodies in a microscopic assay. Members of the spirochete morphogroup were also identified by phase contrast microscopy. The relationship between site-specific detection of bacteria at recall 1 and development of gingivitis at recall 2 or 3 was evaluated by means of logistic regression using generalized estimating equations, from which odds ratios (OR) were estimated. Significance was conservatively defined as OR > 2.0 and P < 0.05. We found that 488 of 1,424 healthy sites developed gingivitis over the 12-month interval between recall 1 and 3. Only the spirochete morphogroup (OR =2.04; P=0.002) was significantly associated with the transition from health to gingivitis. The association of Treponema socranskii with future gingivitis was higher than expected (OR=2.27), but the relationship was not statistically significant (P=0.163). Campylobacter rectus, Eikenella corrodens, Porphyromonas gingivalis, and pathogen-related oral spirochetes did not correlate well with gingivitis (OR < 2.0). Health-associated plaque from 5 sites contained Treponema denticola, and all 5 sites progressed to gingivitis. An OR could not be calculated because T. denticola was not detected in health-associated plaque from stable healthy sites. These findings indicated that the presence of T. denticola and unidentified spirochetes in health-associated plaque was associated with increased susceptibility to gingival inflammation. Future studies assessing a larger panel of dental plaque microorganisms, with shorter intervals between baseline and follow-up assessment, are necessary to more fully evaluate the association between detection of specific organisms at healthy sites and risk for gingivitis.

Adult↗
PubMed1997

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

Most periodontal trials are based on the assumption that the superior treatment, as judged by short-term intangible changes in probing attachment levels (the surrogate), is also the treatment most likely to affect tooth mortality. This assumption is valid if: (1) the surrogate is informative about tooth mortality, and (2) the surrogate captures a substantial proportion of the treatment effect on tooth mortality (e.g., > 50% or 75%). The goal of this study was to evaluate whether both conditions were satisfied in a randomized controlled trial (RCT) of elders at high risk for dental diseases. The results suggested that the first condition for a valid surrogate was satisfied: Both one- and two-year changes in probing attachment level were informative about tooth mortality risk. A 1-mm loss measured over a one-year period was associated with a 56% increased tooth mortality risk (relative risk = 1.56; 95% confidence interval, 1.08 to 2.26; p = 0.017); a 1-mm loss measured over a two-year period was associated with a 102% increased risk for tooth mortality (relative risk = 2.02; 95% confidence interval, 1.26 to 3.25; p = 0.004). The second condition necessary for a valid surrogate could not be confirmed in the present trial. With 95% confidence, it was concluded that one-year changes in probing attachment level measurements did not capture a significant proportion of the treatment effect (point estimate, 6%; 95% confidence interval;-38% to 53%). No useful statements could be made regarding the proportion of treatment effect captured by two-year changes, due to the width of the confidence interval (point estimate, 18%; 95% confidence interval;-151% to 140%). It is concluded that (1) the evidence surrounding the one-year change in probing attachment level indicates that it can be ruled out as being anything more than a weak surrogate marker for tooth mortality, and (2) further research is required to study the validity of two-year change in probing attachment level as a surrogate marker. Due to characteristics of the population and the treatments investigated, the generalizability of these findings to other RCTs is questionable.

Aged↗
PubMed1997

Association of oral spirochetes from sites of periodontal health with development of periodontitis.

The purpose of this investigation was to determine whether the presence of disease-associated bacteria in health-associated plaque correlated with susceptibility to periodontitis over time. Sites of periodontal health were identified in 65 adults. Six months later (recall 1), plaque was collected from sites that remained in periodontal health, and specific bacteria were detected using monoclonal antibodies in a microscopic assay. The spirochete morphogroup was identified by phase contrast microscopy. The relationship between detection at recall 1 and development of periodontitis over two successive 6-month intervals (recalls 2 and 3) was evaluated by means of logistic regression using generalized estimating equations (GEE), from which odds ratios (OR) were estimated and tested for significance. Significant relationships were defined as those having ORs with P < 0.05. Ninety-three of 1,032 sites developed signs of early periodontitis over the 12-month interval between recall 1 and recall 3. The spirochete morphogroup (OR = 3.13, P < 0.001) and pathogen-related oral spirochetes (PROS) (OR = 3.68, P < 0.001) were significantly associated with healthy sites that developed periodontitis. The association of Treponema socranskii was not significant (OR = 3.62, P = 0.0918). Odds ratios for Campylobacter rectus, Eikenella corrodens, and Porphyromonas gingivalis were less than 2.0 and not significant. Treponema denticola was not detected in health-associated plaque from stable health sites and was detected in only three sites that progressed to periodontitis. These findings indicate that the presence of PROS and some unidentified spirochetes in health-associated plaque is associated with increased susceptibility to periodontitis.

Adult↗
PubMed1997

Comparison of a bioabsorbable GTR barrier to a non-absorbable barrier in treating human class II furcation defects. A multi-center parallel design randomized single-blind trial.

This multi-center single-blind study compared clinical outcomes following guided tissue regeneration (GTR) treating human Class II furcation defects with a new polylactic-acid-based bioabsorbable barrier (test treatment) or a non-absorbable ePTFE barrier (control treatment). Clinical parameters evaluated were change in vertical attachment level (VAL), horizontal attachment level (HAL), probing depth (PD), and gingival margin location (REC). Surgical treatment resulted in clinically and statistically equivalent changes when comparisons were made between test and control treatments. VAL gain was 2.0 mm for test and 1.6 mm for control groups; HAL gain was 2.1 mm for both test and control groups. PD reduction was 2.3 mm for the test group and 2.1 mm for the control group. Test sites experienced an additional 0.3 mm of recession beyond baseline; control sites, 0.5 mm. Within-group comparisons showed that the amount of recession was not significantly different from baseline in the test group. Recession in the control group was significantly different from baseline. All other parameters in both the test and control groups were significantly different from baseline. Evaluation of safety data indicated no significant differences between test and control treatments, although there was a strong trend for the control group to have more postoperative abscess or suppuration than test sites (control = 11; test = 4; P = 0.06).

Absorption↗
PubMed1996

Associations between Porphyromonas gingivalis and oral treponemes in subgingival plaque.

Colonization and/or proliferation of Treponema denticola may depend on the presence of Porphyromonas gingivalis. The aims of this study were to confirm this synergistic relationship, to determine whether other oral bacteria were similarly associated with P. gingivalis and to relate coinfection to the periodontal status of plaque donors. Subgingival plaque was collected from every tooth except third molars in 106 subjects who were grouped by their worst periodontal condition. In addition to P. gingivalis, monoclonal antibodies were used to identify Campylobacter rectus, Eikenella corrodens, T. denticola, Treponema socranskii and pathogen-related oral spirochetes. Associations of these bacteria with coinfection by P. gingivalis were assessed by estimated odds ratios. The results indicate that coinfection with P. gingivalis is linked to all tested bacteria, but each pair was associated with distinct periodontal conditions. The distribution of coinfected sites suggests biased colonization of facial surfaces over lingual surfaces.

Adult↗
PubMed1996

Periodontal status and detection frequency of bacteria at sites of periodontal health and gingivitis.

It is generally recognized that bacteria in dental plaque at sites of periodontal diseases are not commonly found at sites of periodontal health. One hypothesis to explain the etiology of periodontitis is that pathogenic bacteria from diseased sites infect healthy sites. It has been suggested that gingival inflammation may predispose sites to colonization by bacteria associated with periodontal diseases. The purpose of this cross-sectional study was to determine whether the detection frequency of selected bacteria at sites of periodontal health or gingivitis differed between subjects who were in good periodontal health, subjects who had gingivitis, or subjects with periodontitis. The clinical status of every tooth (except third molars) from 106 subjects was characterized by means of clinical attachment level, probing depth and by signs of inflammation. Subgingival plaque was collected from mesio-facial and disto-lingual surfaces. Specific monoclonal antibodies were used in an immunocytochemical assay to identify Campylobacter rectus, Eikenella corrodens, Porphyromonas gingivalis, pathogen-related oral spirochetes (PROS, using Treponema pallidum subspecies pallidum monoclonal antibodies), T. denticola (serotypes A-D), T. socranskii subspecies buccale and T. socranskii subspecies socranskii. Differences in detection of bacteria between groups of subjects were measured using odds ratios (OR). Results of this study indicate that PROS was the only identified bacterium at sites of both health and gingivitis that demonstrated a significant positive relationship with the presence of periodontitis. These findings do not prove that bacteria spread from periodontitis sites, nor do they imply that disease necessarily results from infection. However, these data do suggest that some bacteria associated with periodontitis are more likely than others to tolerate conditions at healthy sites and that the presence of periodontitis increases risk of infection at healthy sites.

Adult↗
PubMed1996

A multi-center clinical trial of a new chairside test in distinguishing between diseased and healthy periodontal sites. II. Association between site type and test outcome before and after therapy.

The aim of the present study was to evaluate the association between the outcome of a chairside test measuring gingival crevicular fluid (GCF) levels of the enzyme aspartate aminotransferase (AST) and other clinical measures of disease including probing depth, severity of inflammation, and GCF flow before and after therapy. We studied 91 patients with moderate to severe periodontitis. Eight sites with probing depths between 5 mm and 8 mm and obvious signs of inflammation were selected and designated diseased sites. Four sites with probing depth < or = 3 mm with no or minimal signs of inflammation were selected and designated non-diseased sites in patients. Thirty healthy individuals were enrolled and four sites in each were selected and designated healthy controls. Patients were treated with scaling and root planing and control subjects with supragingival prophylaxis. Measurements including GCF volume, gingival inflammation, and probing depth were performed at screening baseline, 1 week later at pretreatment baseline, and at weeks 2 and 4 after treatment. AST content of GCF was measured using a chairside colorometric test. It was concluded that the outcome of the test is an effective objective measure distinguishing between diseased sites and non-diseased sites in patients and control subjects when evaluated both prior to and following application of therapy. Use of this simple chairside test, when combined with other standard diagnostic procedures, provides an objective measurement permitting improved capacity to distinguish between diseased and non-diseased periodontal sites, and to better assess and monitor the outcome of therapy.

Adult↗
PubMed1995

A survey of endpoint characteristics in periodontal clinical trials published 1988-1992, and implications for future studies.

Endpoints are conditions or events that are associated with individual study subjects and that are used to assess treatment efficacy. 2 types of endpoints can be distinguished: "true" endpoints (reflect unequivocal evidence of tangible benefit to the patient) and "surrogate" endpoints (usually a measure of disease process). The purpose of this study was to survey four aspects of endpoint usage in randomized controlled trials (RCT's) on the treatment of periodontitis: (1) the typical number of endpoints per RCT, (2) the proportion of RCTs using the same endpoint, (3) the proportion of RCTs using true endpoints, and (4) whether treatment choice influenced endpoint choice. 92 publications (1988-1992) reporting on 82 RCT's were identified. The typical number of endpoints per RCT was 6 (range: 1-28). The 3 most frequently used endpoints were mean probing depth (78% of the trials), mean probing attachment level (66%), and the plaque index (37%). In total, 153 distinct surrogate endpoints were defined. Most of these were used infrequently; over 80% of the 153 endpoints were used in fewer than 5 of the 82 trials. No trials used tooth loss as a true endpoint. In the design of an RCT, treatment choice influenced surrogate endpoint choice. Surrogate endpoints based on re-entry surgery were exclusively used for regenerative procedures and microbiological surrogate endpoints were mostly used for RCT's on anti-microbials. The conclusion is that the typical RCT used multiple surrogate endpoints, some of which were used infrequently by other trials. Such endpoint usage characteristics are suitable for exploratory RCTs (designed to identify active treatments or to elucidate treatment mechanisms). The question is raised as to whether periodontal research has reached the point of needing properly designed definitive studies, whose purpose it would be to provide unequivocal evidence of tangible benefits to the patient by the various treatments. If a need for definitive randomized controlled trials is perceived, then the use of (multiple) surrogate endpoints as primary outcomes should be questioned. Surrogate endpoint usage has led to both false positive and false negative conclusions in other chronic disease studies. Endpoint selection and validation in RCTs may be an important element in resolving controversies about periodontal treatments.

Humans↗
PubMed1995

A multicenter clinical trial of PerioGard in distinguishing between diseased and healthy periodontal sites. (I). Study design, methodology and therapeutic outcome.

We designed and performed a multicenter clinical trial to determine the relationship between measurements of the level of the enzyme aspartate aminotransferase (AST) in gingival crevicular fluid (GCF) to other measures used to detect periodontal disease and monitor outcome of treatment, including pocket depth and gingival inflammation. 32 periodontitis patients were enrolled at the University of Washington, Seattle, 30 at the University of Florida, Gainesville, and 34 at the University of Illinois, Chicago. 10 periodontally normal control subjects were enrolled at each location. 8 diseased and 4 healthy sites were designated for study in each patient and 8 healthy sites designated in each control subject. Measures of disease included pocket depth, severity of gingival inflammation, and GCF volume. AST levels were measured using the PerioGard test kit. Clinical measurements were made and GCF samples harvested and tested 2x before and 2x after therapy consisting of scaling and root planing under local anesthetic. Specific design and other issues are discussed, including selection of patients and control subjects, sample size, selection of experimental test sites, methods for assessment of diseased and therapeutic improvement, harvesting of GCF and selection of appropriate biostatistical methods for data analysis. Demographics of the patient populations at the 3 locations are reported. As expected, therapy induced only negligible changes in the measures of disease at healthy sites in control subjects, and relatively minor improvement in healthy sites in patients. In contrast, statistically significant improvement relative to pretreatment baseline status in all 3 measures of disease was observed for diseased sites at all 3 study locations with all p-values less than 0.0002. The magnitude of improvement was comparable to that reported previously by others. The % of PerioGard-positive sites decreased significantly between the screening baseline and both post-treatment visits for patients at all 3 locations, with p values of 0.0001 to <0.0008.

Adult↗
PubMed1995

Do caries explorers transmit infections with persons? An evaluation of second molar caries onsets.

UNLABELLED: Dental caries explorers may become contaminated during routine caries examinations with pathogenic organisms and thereby potentially transmit infections from one tooth to another within a patient. The purpose of this study was to test the hypothesis that the contamination status of explorers influenced the caries risk of second molars. Two explorer contamination statuses were defined: (1) contamination status 1--explorers which had probed a carious molar just prior to examining the second molar, and (2) contamination status 2--sterile explorers versus explorers which had probed several teeth. Caries examinations were performed by 4 dentists on a cohort of 4th grade students in Belize City. The examination dates and sample sizes (n) were: September-October 1989 (n = 1,277), January 1991 (n = 1,111), and January 1992 (n = 961), and January-February 1993 (n = 861). Within this cohort, there were 221 subjects who (1) had at least one pit and fissure carious onset on a caries-free second molar, (2) had no evidence of dental treatments, and (3) were examined by the same examiner during the entire study. After adjusting for confounding variables, the examination of a second molar with a dental caries explorer in either contamination status 1 or 2 had no substantial effect on the caries risk (rate ratio 0.95, 95% confidence interval: 0.77-1.18, and rate ratio 1.18, 95% confidence interval: 0.89-1.56, respectively). If a true rate ratio of 1.7 or greater was associated with the contamination status 1 and 2, these analyses had more than 99 and 80% probability of detecting it, respectively. CONCLUSIONS: Examining a sound second molar with a contaminated dental explorer either does not affect the caries risk, or results in such a small increase in caries risk that it can only be reliably identified in studies where the exposure of sound teeth to contaminated dental explorers is randomized.

Child↗