Comparative study of surface roughness between several finishing and polishing procedures on ormocer-based composite resin and nanohybrid composite resin / 대한치과보철학회지

STATEMENT OF PROBLEM: Proper finishing and polishing enhance both the esthetics and the longevity of restored teeth. Blade finishing technique would be suited for smoothing and finishing. Evaluation of this technique are necessary. PURPOSE: The purpose of this study was to evaluate the blade finishing and polishing procedures on the surface profile and roughness of ormocer-based composite resin and nanohybrid composite resin. MATERIAL AND METHODS: The material included a ormocer-based composite resin (Admira(R) & Admira(R) Flow); a nanohybrid composite resin (Grandio(R) & Grandio(R) Flow). One hundred forty specimens of each group were prepared using a mylar strip and randomly divied into blade finishing and rubber polishing groups (n=10). The average surface roughness (Ra) in micrometers was measured and the surface profile was examined by scanning electron microscopy (SEM) (Magnification X 200). The data were analyzed by Mann-Whitney Test at 0.05 significance level. CONCLUSION: The results of this study indicated that the mylar strip produced the smoothest surface on all materials and among the finishing-polishing methods was not significanct difference (P>0.05). Ormocer-based flowable composite resin performedthe lowest variability in initial surface roughness among the tested materials.

Bronchial responsiveness to methacholine in general population without bronchial asthma / 천식및알레르기

BACKGROUND: Bronchial hbyperresponsiveness (BHR) is a key feature of asthma, and may precede the development of asthma. Genetically determined and acquired factors may contribute to development of BHR. OBJECTIVE: To evaluate expression of bronchial responsiveness to methacholine according to age, sex, smoking habit, and atopy in general population without bronchial asthma, a cross sectional study was performed. METHOD: A total of 1,190 general population who composed of 408 subjects with age less than 19 years (young age group), 621 subjects with age from 20 to 40 years (middle age group), and 161 subjects with age more than 41 years (old age group) were enrolled. Evaluations were made by a questionnaire, serum IgE level and skin prick test to common inhalant allergens, and methacholine bronchial provocation test (MBPT). Bronchial responsiveness were evaluated by positive rate of MBPT (PC,p-methacholine 4 25mg/ml), and slope of dose- response curve (slope, %fall of FEV, / log[last concentration of methacholine, mg/ml]). RESULT: Positive rate of MBPT was 11.0%, and slope (mean+SE) was 10.6+0.2 %/mg/ml. Postive rate of MBPT was more prevalent in the young age group than in middle and old age groups (19.6% vs. 6.6% vs. 6.2%, p<0.05), and slope was higher in young age group than in other groups (14.4+0.4 vs. 8.6+0.3 vs. 8.9+0.5 %/mg/ml, p<0.05). No significant differences in positive rate of MBPT and slope were noted according to sex in young and old age groups. However, in the middle age group, slope was higher in females than in males (9.5+0.4 vs. 7.9+ 0.3 %/mg/ml, p<0.05). No significant differences of slope was observed according to smoking habit in males of middle age group, but in males of old age group, the slope was higher in subjects with smoking habit than those without it (9.6+0.8 vs. 6.5+0.9 %/mg/ml, p<0.05). Significant relationship was observed between geometric value of serum IgE level and slope(r=0. 152, p=0.009). The postive rate of MBPT and slope were significantly higher in subjects with positive skin rea,ctivity to common inhalant allergens than those without it (14.3% vs. 8.6%, p ( 0.05; 11.8+0.4 vs. 9.8+0.3 %/mg/ml, p<0.05). The difference of bronchial responsiveness according to skin reactivity was observed in young and middle age groups, but not in old age group. CONCLUSION: Bronchial responsiveness to methacholine is significantly higher in children than in adults, in middle-aged females than in middle-aged males. Atopy and smoking may have a dif ferent role to determine the bronchial responsiveness depending upon age and sex.