During the development of the microtensile bond-testing method, large variations in bond strengths were noted among serial sections. The reason for these variations is unknown. The purpose of this work was to determine the consistency of resin-dentin bond strengths across the occlusal surface of coronal dentin by dividing composite resin buildups into an array of 1x1 mm beams, the top half consisting of composite resin, and the bottom half consisting of dentin. Extracted human third molars had the occlusal enamel removed as a single section by means of a diamond saw. Resin composite buildups were made after the dentin was bonded with either One-Step or MacBond. After being stored in 37 degrees C water for 1 day, the teeth were vertically sectioned at 1-mm increments into slabs of bonded teeth. Each slab was further subdivided by vertical sections into 1x1x8 mm beams. Each beam was assigned an x-y coordinate and tested for tensile bond strength. Two different clinicians (A and B) performed the same procedures using One-Step in a parallel study. Using One-Step, clinician A obtained a large number of zero bonds in superficial dentin but fewer in deep dentin. This resulted in a very large standard deviation in bond strengths (mean +/- SD of 22+/-20 MPa in superficial dentin and 27+/-14 MPa in deep dentin). Clinician B obtained much higher (p<0.001) and more uniform bond strengths with One-Step (56+/-13 MPa in superficial dentin and 57+/-12 MPa in deep dentin). With MacBond, there were no zero bonds and hence less variation, with a mean of 41+/-13 MPa in superficial dentin and 27+/-12 MPa (x +/- SD) in deep dentin. When pairs of Z100 resin composite cylinders were bonded together with One-Step and then sectioned into an array, there was little variation in regional bond strength (37 +/-1 MPa). Dividing bonded resin composite buildups into an array of 20 to 30 1x1x8 mm beams allows for the evaluation of uniformity of resin-dentin bonds. The method used in this study detected local regional differences in resin-dentin bond strengths. The largest differences were shown to be related to technique rather than to material. The results indicate that resin-dentin bonds may not be as homogenous as was previously thought.
Comparative studies on resin-dentin bond strength and failure mode were performed between bonding over the whole dentin surface. These results suggest that the non-trimming microtensile test may potentially provide more realistic aspects of resin-dentin bonding than the conventional bulk specimen.
Introduction:This study aimed to compare the attitudes towards people with dementia, knowledge of dementia and ageism amongst Taiwanese and Japanese dental hygiene students.
Material and Methods:A total of 328 students participated in this cross-sectional study. Attitudes, knowledge and ageism were assessed using self-reports.Participants' association with older adults or persons with dementia was also assessed. Primary outcomes included attitude, knowledge and ageism amongst students. Secondary outcomes were the factors related to their desire to work with persons with dementia.Results: Data of 175 Taiwanese and 91 Japanese students were analysed. There were significantly more Japanese (69.2%) than Taiwanese (33.2%) students without experience of cohabitation with older adults. More Taiwanese (45.1%) than Japanese students (30.8%) gave a neutral answer regarding their desire to work with persons with dementia. Japanese students scored significantly higher on the attitude and ageism scales than did Taiwanese students; however, the scores of knowledge assessment were approximately the same. Attitude or ageism did not correlate with knowledge amongst students from either country. Logistic regression analysis revealed that the desire to work with persons having dementia was related to ageism and the relationship with these people, irrespective of country.
Conclusion:Although the students had comparable levels of knowledge, there existed significant difference in the attitudes and the degree of ageism between students from Taiwan vs Japan. This finding may prompt improvement of education on dementia, where differences in nationality and lifestyle, including the rate of ageing and family structure, are taken into consideration.
K E Y W O R D Sageism, attitude, dementia, dental hygiene student
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