No abstract

Toothbrushes wear out and progressively lose their ability to clean as the bristles abrade and become curled and matted. To study the factors that influence this process, we developed a quantitative measure of bristle splaying (wear index) and a method for judging and ranking the overall state of brush deterioration (wear rating) and used these to determine the effects of the individual user, brush design, time in use, and bristle material. Wear index is the average increase in brush-head dimensions normalized for maximum bristle length, and is dimensionless. Wear rating is a subjective means of classifying the increasing severity of deterioration on a scale of 0 to 3. The wear characteristics of a variety of commercial and experimental brushes with different design features were determined. Test variables were time in use, brush design (e.g., geometry and size of the brush head), and bristle composition. Time of use, the individual user, and bristle composition were found to have the strongest influences on splaying, and brush design was found to have the least influence. The wear index offers a quantitative means of comparing brushes of different dimensions at various stages of splaying. The wear rating, although qualitative, is a quick means of ranking brushes in various stages of deterioration. The two methods correlate (R2 = 0.87), and both are sensitive to several factors that affect brush durability. Therefore, these methods appear to be suitable not only for research, but also for quality control, the setting of standards, and for substantiation of advertising claims.

In patients undergoing revascularization for AMI, initial stent placement is associated with improvements in several dimensions of health status during the first six months of follow-up. In the absence of differences in mortality, these findings add to the overall argument in favor of initial stenting in patients treated with mechanical reperfusion for myocardial infarction.

Some confusion exists in the literature whether correlations exist between gingivitis severity and plaque levels as measured by the corresponding indices. The results of a clinical trial and a re‐analysis of literature data indicate that a strong statistical correlation exists between the Löe‐Silness Gingival Index values and both the Löe and the Quigley‐Hein Plaque Index measurements. Furthermore, regression analyses also indicate that Löe‐Silness Gingival Index can be expressed as linear functions of either the Löe Plaque Index or the QuigleyHein Plaque Index and that for each unit increment in the mean plaque index values a half unit increase in the gingival index value can be expected.