| A bivariate multi-level model, which avoids mathematical coupling in the study of change and initial periodontal attachment level after therapy. | |
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MedLine Citation:
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PMID: 17265045 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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When relating the change of periodontal attachment level to its baseline value, mathematical coupling has to be taken into account. Oldham's strategy of testing the differences in variances of two repeated measurements was recently advocated as a possible solution. Here, a simple bivariate three-level (site and subject with a lowest level specifying the multivariate structure) model is introduced where gingival units (sites) were nested in subjects. It allows the easy interpretation of the variance-covariance structure and fixed model estimates, and provides an unbiased estimate of the correlation between the mean and change of periodontal measurements. The properties of this model are exemplified using data of a study on the clinical effects of non-surgical periodontal therapy in adults. Based on the covariance terms, correlation between the change in clinical attachment after therapy and the mean of the pre-operative and post-operative attachment level was very low (about -0.11, p < 0.001) at the site level, and not significant at the subject level. Regarding the attachment level, differential treatment effects may be neglected. With regard to periodontal probing depth, however, patients with larger extent and severity would benefit more from treatment. The present communication provides an easy strategy for the avoidance of mathematical coupling in the study between change and initial value by employing a bivariate multi-level model. |
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Authors:
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Hans-Peter Müller |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2007-01-31 |
Journal Detail:
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Title: Clinical oral investigations Volume: 11 ISSN: 1432-6981 ISO Abbreviation: Clin Oral Investig Publication Date: 2007 Sep |
Date Detail:
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Created Date: 2007-08-01 Completed Date: 2007-10-18 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9707115 Medline TA: Clin Oral Investig Country: Germany |
Other Details:
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Languages: eng Pagination: 307-10 Citation Subset: D |
Affiliation:
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Faculty of Dentistry, Kuwait University, Safat, Kuwait. hp.muller@hsc.edu.kw |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Algorithms Anti-Infective Agents, Local / therapeutic use Chlorhexidine / analogs & derivatives, therapeutic use Dental Scaling Gingiva / pathology Humans Models, Statistical* Mouthwashes / therapeutic use Oral Hygiene Periodontal Attachment Loss / pathology, therapy* Periodontal Index Periodontal Pocket / pathology, therapy Periodontics / statistics & numerical data Periodontitis / therapy Root Planing |
| Chemical | |
Reg. No./Substance:
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0/Anti-Infective Agents, Local; 0/Mouthwashes; 18472-51-0/chlorhexidine gluconate; 55-56-1/Chlorhexidine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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