口腔医学专业英文

亲爱的口腔医学生们  So nice to meet you here！

最近在学习《口腔医学专业英语》这本书，会在这里记录下我精读的过程哦 也欢迎你的加入！

我们的口号是：加油加油，你紫腚行！

Unit1 Development, Structure and pH of Dental Plaque牙菌斑的形成、结构及pH值

Teeth provide ideal conditions for bacterial colonization and growth. In contrast to mucosal surfaces, the surfaces of teeth are not constantly renewed by shedding of colonized epithelial cells. Furthermore, some sites on the teeth, e. g. approximal surfaces and occlusal fissures, are particularly well protected from the shearing forces from oral mucosa and food and allow undisturbed accumulation of bacteria. These sites correspond to the areas of the tooth where caries is first detected.

Microbial colonization of teeth, however, is not merely a question of passive retention, but requires that bacteria adhere to the surface. The mechanisms involved in adherence are very complex and not yet fully understood. Initially, bacteria are thought to be unspecifically associated with the tooth surface under the influence of Van der Wall's attractive forces as well as repulsive negative electrostatic forces. A high degree of surface hydrophobicity may facilitate an attachment. A firm attachment may subsequently be achieved by specific mechanisms.

Microorganisms do not attach themselves directly to the mineralized tooth surface as the teeth are always covered by an acellularproteinaceous film, the pellicle. The pellicle forms on the "naked" tooth surface within minutes to hours. In uncolonized areas the pellicle reaches a thickness of 0.01-1μm within 24 hours. The major constituents of the pellicle are salivary glycoprotein, phosphoproteins, lipids, and to a lesser extent components from the gingival crevicular fluid.

Because of its permselective nature restricting transport of ions in and out of the dental hard tissues, the pellicle may play an important modifying role in caries. Thus it has been shown that the presence of a pellicle inhibits subsurface demineralization of enamel in vitro. It has not been examined, however, as to whether an experimental increase in thickness of the pellicle, such as observed in association with frequent mouth rinses with milk or cream, provides further protection against permselective of the enamel.

The composition of the pellicle has received considerable attention because of its potential role in determining the composition of the initial microflora. Thus, it has been speculated that the surface characteristics of different materials may influence the composition of aminoacids in the pellicle and thereby modify the number of potential adsorption sites for different bacterial species. However, so far no studies have systematically analyzed the association between aminoacids in the pellicle and the type of the initial colonizers. Furthermore, there is a lack of information about the carbohydrate content in pellicles from different types of surfaces. As oligosaccharides of pellicle glycoproteins may be responsible for mediating attachment of initial colonizers to teeth, it is not possible to draw conclusions about the relative effect of different pellicle components upon the pattern of colonization in vivo.

那今天就到这里啦，感谢努力的自己❥