Study on mechanisms of vertical root fracture

碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 88 === Vertical root fracture(VRF)is difficult in diagnosis and treatment. According to the literature review, VRF occurs more frequently in teeth that have received endodontic treatment. There are some studies working on the possible causes of vertical root fractures,...

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Main Author: 蔡宜玲
Other Authors: 藍萬烘
Format: Others
Language:zh-TW
Published: 2000
Online Access:http://ndltd.ncl.edu.tw/handle/54656404663376025901
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spelling ndltd-TW-088NTU015900122016-01-29T04:18:53Z http://ndltd.ncl.edu.tw/handle/54656404663376025901 Study on mechanisms of vertical root fracture 垂直牙根斷裂之斷裂機制的研究 蔡宜玲 碩士 國立臺灣大學 臨床牙醫學研究所 88 Vertical root fracture(VRF)is difficult in diagnosis and treatment. According to the literature review, VRF occurs more frequently in teeth that have received endodontic treatment. There are some studies working on the possible causes of vertical root fractures, but the etiologies of this disease still remained uncertain. Besides, VRF can also be found clinically in non-endodontically treated teeth. The relative literature is sparse, therefore, its possible causes are yet to be known. Understanding the factors that predispose a tooth to fracture is essential to develop thorough concept of diagnosis, treatment, and prevention. The specific aims of this study were as follows: 1. the characteristics of VRF by clinical survey; 2. to observe the fracture characteristics; 3. to understand more comprehensive in its possible etiologies and mechanisms; 4. to compare the biomechanical properties of dentin in VRF teeth with those of normal ones. One hundred and twenty teeth with the diagnosis of VRF were included in this study. The patients’ dental history, clinical manifestation, and radiographic findings were recorded. All the fractured teeth were divided into 6 groups: 1. Group ED  endodontically treated teeth, operative restorations without posts; 2. Group EC  endodontically treated teeth, crowns or bridges reconstruction without posts; 3. Group EPC  endodontically treated teeth, crowns or bridges reconstruction with posts; 4. Group N  non-endodontically treated teeth without any restorations; 5. Group ND  non-endodontically treated teeth with operative restorations; 6. Group NC  non-endodontically treated teeth with crowns or bridges reconstruction. Stereomicrographic observation and SEM fractographic study were utilized to determine the directions of crack initiation and propagation, and the fracture patterns. Vickers microhardness and elastic modulus of dentin were determined by the dynamic microindentation test in order to understand the differences of mechanical properties between vertical root fractured teeth and normal ones. The results revealed that: 1. 87% VRF occurred in endodontically treated teeth with crowns or bridges reconstruction. It implies that restorations such as full crowns or bridges do not prevent VRF. 2. Fractures extended primarily buccolingually not only in endodontically treated teeth but in non-endodontically ones. 3. Most fractures extended to reconstructed crown margins in group EC, EPC, and NC. However, in group ED, N, and ND, fractures never extended within 0.5㎜ to CEJ. It appears that DEJ may play an important role in resisting crack propagation. 4. VRF is chronic fracture as well as a fatigue fracture. 5. The change of biomechanical properties of root dentin seems not to affect the occurrence of vertical root fracture. 藍萬烘 林俊彬 2000 學位論文 ; thesis 100 zh-TW
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language zh-TW
format Others
sources NDLTD
description 碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 88 === Vertical root fracture(VRF)is difficult in diagnosis and treatment. According to the literature review, VRF occurs more frequently in teeth that have received endodontic treatment. There are some studies working on the possible causes of vertical root fractures, but the etiologies of this disease still remained uncertain. Besides, VRF can also be found clinically in non-endodontically treated teeth. The relative literature is sparse, therefore, its possible causes are yet to be known. Understanding the factors that predispose a tooth to fracture is essential to develop thorough concept of diagnosis, treatment, and prevention. The specific aims of this study were as follows: 1. the characteristics of VRF by clinical survey; 2. to observe the fracture characteristics; 3. to understand more comprehensive in its possible etiologies and mechanisms; 4. to compare the biomechanical properties of dentin in VRF teeth with those of normal ones. One hundred and twenty teeth with the diagnosis of VRF were included in this study. The patients’ dental history, clinical manifestation, and radiographic findings were recorded. All the fractured teeth were divided into 6 groups: 1. Group ED  endodontically treated teeth, operative restorations without posts; 2. Group EC  endodontically treated teeth, crowns or bridges reconstruction without posts; 3. Group EPC  endodontically treated teeth, crowns or bridges reconstruction with posts; 4. Group N  non-endodontically treated teeth without any restorations; 5. Group ND  non-endodontically treated teeth with operative restorations; 6. Group NC  non-endodontically treated teeth with crowns or bridges reconstruction. Stereomicrographic observation and SEM fractographic study were utilized to determine the directions of crack initiation and propagation, and the fracture patterns. Vickers microhardness and elastic modulus of dentin were determined by the dynamic microindentation test in order to understand the differences of mechanical properties between vertical root fractured teeth and normal ones. The results revealed that: 1. 87% VRF occurred in endodontically treated teeth with crowns or bridges reconstruction. It implies that restorations such as full crowns or bridges do not prevent VRF. 2. Fractures extended primarily buccolingually not only in endodontically treated teeth but in non-endodontically ones. 3. Most fractures extended to reconstructed crown margins in group EC, EPC, and NC. However, in group ED, N, and ND, fractures never extended within 0.5㎜ to CEJ. It appears that DEJ may play an important role in resisting crack propagation. 4. VRF is chronic fracture as well as a fatigue fracture. 5. The change of biomechanical properties of root dentin seems not to affect the occurrence of vertical root fracture.
author2 藍萬烘
author_facet 藍萬烘
蔡宜玲
author 蔡宜玲
spellingShingle 蔡宜玲
Study on mechanisms of vertical root fracture
author_sort 蔡宜玲
title Study on mechanisms of vertical root fracture
title_short Study on mechanisms of vertical root fracture
title_full Study on mechanisms of vertical root fracture
title_fullStr Study on mechanisms of vertical root fracture
title_full_unstemmed Study on mechanisms of vertical root fracture
title_sort study on mechanisms of vertical root fracture
publishDate 2000
url http://ndltd.ncl.edu.tw/handle/54656404663376025901
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