Dissertation > Excellent graduate degree dissertation topics show

Study on the Erovise Wear Properties of Human Teeth in Citric Acid

Author: HuangHuan
Tutor: ZhengJing
School: Southwest Jiaotong University
Course: Mechanical Design and Theory
Keywords: Human teeth Erosive wear Gitric acid
CLC: R783.5
Type: Master's thesis
Year: 2010
Downloads: 28
Quote: 2
Read: Download Dissertation

Abstract

With a worldwide increase in the ingestion of acidic soft drinks, erosive wear of human teeth is becoming normal, especially in young people. Previous studies mostly focused on the friction and wear behaviors of human teeth in artificial saliva. Their erosive wear behaviors in acid medium are still far from being well understood. Therefore, understanding of the erosion wear behaviors of human teeth in acid medium would extend bio-tribology and help the clinical treatment of toothwear.The wear behaviors of human teeth have been tested under ball-on-flat contact using a reciprocating apparatus in 0.001 M citric acid medium. Various analyses by using microhardness tester, laser confocal scanning microscopy (LCSM), scanning electron microsopy(SEM),energy dispersive spectroscope(EDX), profilometer have been performed. Main conclusions are drawn as follows:1. Wear loss of enamel almost increases linearly with the number of cycles in citric acid, and erosion caused by acid-attack has a significantly influence on the wear behaviors of enamel. Compared with artificial saliva, the friction coefficient of enamel is lower and fluctuates more significantly in citric acid. The worn surface of enamel exhibits more significant delamination trace and higher wear loss in citric acid than in artificial saliva.2. Increasing the normal load causes a progressive increase in the wear loss of enamel and a change of its wear mechanism in citric acid. Given that erosion dissolution softens the surface of enamel, delamination pits and ploughing caused by adhesion are dominant for the wear of enamel under low load. With the load increasing, brittle fracture by the loading force aggravates. As a result, obvious flake delamination happens under high load. It is found that the effect of erosion on the wear behaviors of enamel under low normal load is more obvious than under high normal load.3. Erosive wear behaviors of human teeth depend strongly upon its age. Young permanent teeth have better resistance against erosive wear than that of the primary teeth and old permanent teeth. Compared with the young permanent teeth, more massive delamination happens for the primary teeth, especially for the old permanent teeth, accompanying with stronger fluctuation in the evolution of friction coefficient.4. Erosive wear behaviors of a tooth are closely associated with its microstructure. Better resistance against erosive wear is observed in the enamel zone than in the dentin zone. Furthermore, the erosive wear properties of tooth depend strongly on its microstructure orientation. In citric acid, a tooth shows better wear-resistance along the occlusal section than along the axial section.

Related Dissertations

CLC: > Medicine, health > Oral Sciences > Oral orthotics > Journal of Orthodontics
© 2012 www.DissertationTopic.Net Mobile