A study on the effects of chewing patterns to occlusal contact points and chewing efficiency 저작형태가 교합접촉 및 저작 능 률에 미치는 영향에 관한 연구

Thesis (master`s)--서울대학교 대학원 :치의학과 치과보철학전공,1995.Maste

A Study on the effects of texture of food on chewing movements and EMG of masticatory muscle

학위논문(박사)--서울대학교 대학원 :치의학과 치과보철학전공,1998.Docto

A study on the effects of texture of food on chewing movements and EMG of masticatory muscle

To elucidate the effects of food texture such as hardness, cohesiveness, adhesiveness on mastication procedure, the electromyographic activity (EMG) of the masticatory muscles and the chewing movements were analyzed in eighteen young subjects during ordinary chewing. Seven different foods were selected by sensory texture profiling and mechanical test with texturometer; egg white, sausage, pizza cheese, yang-geng, biscuit, peanut and almond. The indexes of jaw movements used were the chewing number, chewing time, maximum opening, average opening, closing velocity and opening velocity. The EMG indexes analyzed were maximum and average integrated amplitude of the anterior temporal and masseter muscles. The results obtained were as follows. 1. The chewing time and chewing number, mandibular displacement and mandibular movement velocity were not changed by the hardness, cohesiveness and adhesiveness of the food (p>0.05). 2. The harder food materials showed a higher amplitude of the anterior temporal muscle integrated EMGs than the softer ones (p<0.05). 3. The maximum and average integrated EMGs of the masseter muscle increased with the increase of hardness of the food (p<0.05). 4. The integrated EMGs of preferred side and non-preferred side masticatory muscles increased with the increase of hardness of the food (p<0.05). 5. The adhesiveness and cohesiveness of the food were not the determining factor to the integrated EMGs of masticatory muscles (p<0.05)

Correlation between microhardness and wear resistance of dental alloys against monolithic zirconia

PURPOSE. The aim of this study is to compare the hardness according to the conditions of metal alloys. Moreover, the correlation between the cast crown hardness before and after wear testing and the degree of wear for each dental alloy was assessed. MATERIALS AND METHODS. Cast crowns of three metal alloys (Co-Cr, gold, and Ni-Cr alloys) opposing smooth-surface monolithic zirconia were used. The Vickers microhardness of the ingot (which did not undergo wear testing) and the cast crown before and after wear testing were measured for each alloy. Two-way ANOVA and Scheffe tests were used to compare the measured hardness values. Moreover, the Pearson correlation coefficient was used to evaluate the relationship between the surface hardness and the wear of the cast crown (a=.05). Results. There was no significant difference in the hardness before and after wear testing for the gold alloy (P &gt;.05); however, the hardness of the worn surface of the cast crown increased compared to that of the cast crown before the wear tests of Ni-Cr and Co-Cr alloys (P &lt;.05). Furthermore, there was no correlation between the wear and hardness of the cast crown before and after wear testing for all three metal alloys (P &gt;.05). CONCLUSION. There was a significant difference in hardness between dental alloys under the same conditions. No correlation existed between the surface hardness of the cast crown before and after wear testing and the wear of the cast crown