title: Critique of Kingman's methods of projecting long-term relative efficacy of products exhibiting small short-term efficacy.
abstract: This paper critically reviews Kingman's "methods of projecting long-term relative efficacy of products exhibiting small short-term efficacy," a report he prepared for a scientific workshop on the relative anticaries efficacy of fluoride dentifrices, which reveals serious deficiencies. Of the three specific models that Kingman suggests, the compound growth model (CGM), which leads to the largest projected future percentage reductions, is based on a false premise of an increasing universe of caries-free surfaces available for caries-attack with the passage of time. The second suggested model, the demineralization square root model (DSR), is supported only by a personal communication, unavailable for scrutiny. The third suggested model, a stabilization model (STA) is plausible, but unsupported. Other plausible models for extrapolating short-term observed effects are ignored by Kingman. Most of Kingman's choices of data illustrations to fit his suggested models are ill-chosen because the studies were repeated cross-sectional surveys or involved the delivery of systemically and topically delivered fluorides, which contraindicate their use. The most serious breach is Kingman's selective use of subsets of data from two long-term studies of fluoride dentifrices that support his premise, when other, more comprehensive data from the same studies do not. He also ignores findings from other studies that fail to support his suggested models. Kingman's report fails to prove that studies which show small short-term effectiveness after 1, 2 or 3 years will lead to greater relative effectiveness after long periods of use.
mesh_terms: D002327:Cariostatic Agents / Q000627:therapeutic use*; D002648:Child; D002986:Clinical Trials as Topic; D004245:DMF Index; D003627:Data Interpretation, Statistical; D003731:Dental Caries / Q000517:prevention & control*; D018865:Dental Research / Q000379:methods* / Q000706:statistics & numerical data; D003802:Dentifrices / Q000627:therapeutic use; D004341:Drug Evaluation / Q000379:methods*; D005459:Fluorides / Q000627:therapeutic use; D005544:Forecasting; D006801:Humans; D008962:Models, Theoretical; D011785:Quality Assurance, Health Care; D013997:Time Factors
chemical_list: D002327:Cariostatic Agents; D003802:Dentifrices; D005459:Fluorides