Nicotine increased human gingival fibroblast-mediated collagen degradation, in part through the activation of membrane-associated MMPs. Nicotine and P. gingivalis had an additive effect on human gingival fibroblast-mediated collagen degradation.

HGFs exposed to nicotine, P. gingivalis LPS, or a combination of both agents increased the expression of multiple cytokines.

This study was designed to evaluate the use of salivary cotinine, salivary thiocyanate, and expired-air carbon monoxide as biochemical validation measures for assessing the smoking status of adults. The participants were 20 known non-smokers plus 216 admitted smokers and 102 proclaimed quitters participating in a clinical trial of approaches to facilitate smoking cessation. Conventional analytical procedures were utilized. By use of data from known non-smokers and admitted smokers, the sensitivity and specificity of the validation measures were as follows: salivary cotinine, 99% and 100%; expired-air carbon monoxide, 96% and 100%; and salivary thiocyanate, 67% and 95%, respectively. The salivary cotinine and expired-air carbon monoxide tests confirmed smoking cessation for 55% and 74%, respectively, of the proclaimed quitters. The length of time since quitting was significantly related to the results observed with the latter measures. Consideration of these observations along with various practical factors suggests that expired-air carbon monoxide assays may be the validation measure of choice for most clinical trials.

Research suggests that high-quality formative assessment has a strongly positive effect upon student learning. Unfortunately, formative assessment does not appear to be frequently used in didactic dental curricula. Our hypothesis was that providing students with practice online exam questions would enable those who voluntarily took the exam to perform better on subsequent summative exams than did students who did not utilize this opportunity. A test bank of exam questions was written for dental students enrolled in two different biomedical science courses. Half the questions were arbitrarily assigned to an electronic test site; the other half were used as a written summative classroom exam taken later. Students who took the online formative exam in the first semester course scored 8.8 percent higher on the summative exam than did those who did not take the practice exam. This represents almost a full letter grade higher for the formative exam-takers. Students who took the formative online exam in the second semester course scored 5.2 percent higher on the summative exam than did the non-takers. Both of these differences were statistically significant. Under these experimental circumstances, providing formative online exams appeared to promote student performance as reflected by higher scores on the summative exams.

Cytologic and cytogenetic studies were performed to assess the prevalence of somatic cell genetic damage in 48 young adults equally divided to represent users and nonusers of smokeless tobacco. Exposure was ascertained by measuring saliva cotinine using capillary gas chromatography. Squamous epithelial cells sampled from the oral mucosa demonstrated significant cytologic alterations associated with tobacco exposure. The frequency of micronucleated cells was significantly (P less than .01) higher in the labial mucosa of exposed (2.22%) compared to unexposed (0.27%) individuals. The frequency of micronuclei varied widely between exposed subjects but was higher in heavily (2.48%) compared to lightly (1.29%) exposed individuals as measured by saliva cotinine levels. Morphologic classification of epithelial cell nuclei showed that the frequency of cells with normal nuclear structure was significantly (P less than .01) reduce in exposed individuals. Analysis of oral epithelial cells of five additional nonusers of smokeless tobacco but wearers of orthodontic appliances to stimulate abrasion demonstrated no difference from the nonexposed control group. Unlike the case with cigarette smokers, peripheral lymphocyte sister-chromatid exchange frequency was not affected by exposure to smokeless tobacco. The oral cytology data, however, support an interpretation of exposure-dependent nuclear alterations, including micronuclei, in the oral epithelium associated with the use of smokeless tobacco. Altogether, results suggest that use of smokeless tobacco may cause genetic damage to cells in the oral epithelium.

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This study was designed to compare various salivary parameters between smokers and non-smokers and to determine the influence of a nicotine-containing chewing gum (used to aid in quit-smoking efforts) upon these same parameters. At the baseline examination, subjects were assigned to one of three groups: non-smokers who did not utilize any gum, smokers provided a nicotine-containing gum, and smokers provided a placebo gum. Saliva was collected from all subjects and analyzed for acidogenicity and buffer pH as well as for levels of thiocyanate, lactoperoxidase, lysozyme, lactoferrin, and secretory IgA. After 15 weeks of gum usage, saliva was again collected from each subject and the identical analyses performed. Significant differences were observed between smokers and non-smokers with regard to three parameters: The saliva of smokers contained greater concentrations of thiocyanate and lower concentrations of lactoferrin, at the baseline examination and after the 15-week test period. In addition, the CO content of alveolar air was higher in smokers at both examination periods. In contrast, the use of the nicotine gum per se had no effect on any of the test parameters.

No abstract