Assessment of Relationships Between Site‐Specific Variables

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142021/1/jper0368.pd

A Re-analysis of Caries Rates in a Preventive Trial using Poisson Regression Models

The analysis of caries incidence in clinical trials has several challenging features: (1) The distribution of the number of caries onsets per patient is skewed, with the majority of patients having few or no cavities; (2) the number of surfaces at risk varies (i) over time and (ii) between patients, due to eruption and exfoliation patterns, dental diseases, and treatments ; (3) surfaces within a patient differ in their caries susceptibility, and (4) caries onsets within a patient are correlated due to shared host factors. Recent statistical developments in the area of correlated data analyses permit incorporation of some of these characteristics into the analyses. With Poisson regression models, the expected number of caries onsets can be related to the number of surfaces at risk, the time they have been at risk, and surface- and subject-specific explanatory variables. The parameter estimated in these models is an epidemiological measure of disease occurrence: the disease incidence rate (caries rate) or the rate of change from healthy (sound) to diseased (carious). Differences and ratios of these rates provide standard epidemiological measures of excess risk. To illustrate, Poisson regression models were used for exploratory analyses of the Ylivieska xylitol study.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67228/2/10.1177_00220345940730021401.pd

The Utility of the BANA Test for Monitoring Anaerobic Infections due to Spirochetes (Treponema denticola) in Periodontal Disease

Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus each possesses an enzyme(s) that hydrolyzes the synthetic substrate benzoyl-DL-arginine-naphthylamide (BANA). The presence of these organisms in a subgingival plaque sample can be determined by the ability of the plaque to hydrolyze BANA. In the present study, we describe the usefulness of the BANA test at various stages of a clinical trial of the efficacy of metronidazole in the treatment of periodontal disease. A BANA-positive test was significantly associated with high levels and proportions of spirochetes in the plaque, so that it provided information comparable with that which could be obtained by a microscopic examination of the plaque. Patients with such anaerobic spirochetal infections were randomly assigned to a group receiving either metronidazole or placebo (250 mg, three times a day) for one week and whose teeth were scaled and root-planed. The advantages of the decision that metronidazole be used were apparent from the comparison with the results obtained in the patients who received only the scaling and root planing. The initially BANA-positive teeth in the patients treated with metronidazole, scaling, and root planing gained attachment and exhibited a significant reduction in the need for periodontal surgery, when compared with the BANA-positive teeth in the patients who received only placebo, scaling, and root planing. After the conclusion of this therapy, those teeth with persistent BANA-positive plaques had significantly higher proportions and levels of spirochetes than did the teeth with BANA-negative plaques. A tooth site which tested BANA-positive after the initial therapy lost significantly more attachment in the year following active treatment than did a tooth site that tested BANA-negative, i.e., a mean difference of 0.48 mm per year. The ability of the BANA test to detect an anaerobic infection due to the BANA-positive species and possibly to predict future attachment loss indicates that this test may be helpful in the management of the periodontally diseased patient.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67896/2/10.1177_00220345900690101301.pd

Multi‐Center Clinical Evaluation of a Chairside Method for Detecting Certain Periodontopathic Bacteria in Periodontal Disease

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141076/1/jper0189.pd