Studies have reported that the primary cause of fragment loss is new dental trauma or the nonphysiological use of the restored tooth. 研究认为，牙碎片缺失的原发性原因是新近牙体创伤或对已修复牙齿施加非生理性作用力。
Depth and particle size were primary and secondary environment variables that influence the community structure of brachyuran crabs in the present geographic region. 深度与沙粒粒径大小，分别为影响调查区域内螃蟹群聚结构之主要与次要因素。
