Surface topography and bond strengths of feldspathic porcelain prepared using various sandblasting pressures.

OBJECTIVE: The purpose of this study was to determine the bond strength of composite resin to feldspathic porcelain and its surface topography after sandblasting at different pressures. METHODS: In this in vitro study, 68 porcelain disks were fabricated and randomly divided into four groups of 17. The porcelain surface in group 1 was etched with hydrofluoric acid. Groups 2, 3, and 4 were sandblasted at 2, 3 and 4 bars pressure, respectively. Surface topography of seven samples in each of the four groups was examined by a scanning electron microscope (SEM). The remaining 40 samples received the same silane agent, bonding agent, and composite resin and they were then subjected to 5000 thermal cycles and evaluated for shear bond strength. Data were analyzed using one-way anova. The mode of failure was determined using stereomicroscope and SEM. RESULTS: The highest shear bond strength was seen in group 4. however, statistically significant differences were not seen between the groups (P = 0.780). The most common mode of failure was cohesive in porcelain. The SEM showed different patterns of hydrofluoric acid etching and sandblasting. CONCLUSION: Increasing the sandblasting pressure increased the surface roughness of feldspathic porcelain but no difference in bond strength occurred.

Relationship of Gingival Pigmentation with Passive Smoking in Women.

BACKGROUND: Oral mucosal pigmentation is among the most common findings in smokers, affecting smile esthetics. Passive smoking significantly compromises the health of non-smoker individuals particularly women. The purpose of this study was to assess the relationship of passive smoking with oral pigmentation in non-smoker women. MATERIALS AND METHODS: This historical-cohort study was conducted on a case group of 50 married women who were unemployed, not pregnant, non-smoker, had no systemic condition causing cutaneous or mucosal pigmentation, were not taking any medication causing cutaneous or mucosal pigmentation and had a heavy smoker husband. The control group comprised of 50 matched females with no smoker member in the family. Both groups were clinically examined for presence of gingival pigmentation and the results were analyzed using chi-square and logistic regression tests. RESULTS: Gingival pigmentation was found in 27 (54%) passive smokers and 14 (28%) controls (P=0.01). The odds ratio (OR) of gingival pigmentation in women exposed to secondhand smoke of their husbands (adjusted for education and having a smoker parent at childhood) was 3 (95% confidence interval; CI: 1.26 - 7.09). House floor area was correlated with gingival pigmentation in female passive smokers (P=0.025). CONCLUSION: This study was the first to describe the relationship between secondhand smoke and gingival pigmentation in women and this effect was magnified in smaller houses.