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it is generally present in the amount of 70 to 80 per cent.
     Conventional products most often contain crystalline quartz and/or lithium glass ceramics, however, other fillers, such as calcium silicate, glass beads and glass fibers have been used. As some radiopacity is desirable in a restoration, this is achieved by filler blends containing barium and strontium glasses and most recently lanthanum glass.
     Particle size distribution is an important consideration for the filler. In most conventional composites, the distribution ranges from l to 100 blicrometers. Generally, blends of fine particles     (l-20pm) and coarse particles (<100um) are employed.
                                         Coupling Agents
     A stable, adhesive bonding of the filler to the resin is essential for strength and durability in the composite. Thus, the manufactures coat the surface of the filler with a suitable coupling agent. Such agents may also act as a stress absorber at the filler-resin interface. Vinyl silane coupling agents were first used. These have now been replaced by more reactive compounds, such as A- 174 (methacryloxypmpyltrimethoxysilane).

VOCABULARY

l. Composite                                复合树脂
  dental composite resin                      牙科复合树脂
  dental composite restorative materials          牙科复合树脂充填材料
2. conventional composite                     传统(型)复合树脂
  traditional composite                       传统(型)复合树脂
3. microfilled composite                       微细填料(型)复合树脂
4. hybrid composite                          混合填料(型)复合树脂
5. organic binder                             有机粘合(结)剂
6. inorganic filler                             无机填料
7. polymerization                             聚合作用
8. coupling agent                             偶联剂
9. resin matrix      &n本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。