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標題: | 建立人工硬化牙本質模型用於體外微伸拉黏著強度測試 Simulation of Artificial Sclerotic Dentin Model for in vitro Micro-tensile Bond Strength Test |
作者: | Pei-Ying Lu 呂佩穎 |
指導教授: | 姜昱至(Yu-Chih Chiang) |
關鍵字: | 硬化牙本質,牙本質小管,奈米級X光電腦斷層掃描,牙本質黏著劑,微拉伸黏著強度, sclerotic dentin,dentinal tubule,nano-CT,dental adhesive,micro-tensile bond strength, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 目前關於牙本質黏著劑用於齲損牙本質上之黏著強度測試中的體外牙本質模型為兩大類:使用不同pH值的去礦化與再礦化循環溶液,或在生物反應器下創造之齲齒環境所製造之人工齲損(硬化)牙本質。然而,臨床上被齲齒、磨損、咬耗、磨耗或酸蝕等影響之牙本質病灶區,常可見到透明化之深棕色或黃褐色的硬化牙本質層,於顯微結構下可觀察到其牙本質小管內充滿Mg-β-tricalcium phosphate結晶。但是目前為止,尚沒有體外人工牙本質模型能製造具有類似自然牙齒牙本質小管內硬化結晶之結構成分與形態,且能廣泛用於模擬以上各種真實臨床狀況。
因此本研究目的為: 建立標準化模擬硬化牙本質層之體外模型,且能應用於牙本質黏著測試。 本研究總共分為三大部分:第一部份為觀察及分析因齒頸部磨損產生的自然硬化牙本質之顯微結構與組成成分;第二部分主要是建立標準化的人工硬化牙本質實驗模型,以不同配方之sclerotic dentin simulation solutions令牙本質小管內產生結晶,並分析其生長長度、化學組成及結晶性,調整出最佳配方後,利用奈米級電腦斷層掃描,與自然硬化牙本質及正常健康牙本質進行孔隙度及礦化程度分析;第三部份則是利用建立出的人工硬化牙本質進行牙本質黏著劑之微伸拉黏著強度測試。 結果顯示自然硬化牙本質內結晶生成與的膠原蛋白絲有關,小管內充滿由含有Mg的tricalcium phosphate所構成的菱形狀結晶,且愈接近外界處牙本質小管管壁上結晶層愈厚。本實驗建立之人工硬化牙本質模型能令牙本質小管內形成深度至少500 μm之結晶,主要成分應為OCP (octacalcium phosphate)。另外實驗中牙本質小管內晶體由管壁往管中央方向逐漸生成結晶,且初期於管壁上形成的晶體粒徑較小;後期於管中央形成的晶體粒徑較大。奈米級電腦斷層掃描分析結果顯示本研究中所建立的人工硬化牙本質模型與自然牙齒頸部磨損所產生的硬化牙本質於病灶表面往下至50 μm深之範圍內有相似的孔隙率,礦物質密度略高於自然硬化牙本質,其微拉伸黏著強度(25.8±8.1 MPa)低於健康牙本質(30.9±7.6 MPa),但無統計學上顯著差異(p>0.05),且較自然硬化牙本質(18.6±5.1 MPa)高。由目前結果我們得到以下三點結論:(1).自然硬化牙本質應是從生物礦化與生物去礦化的過程中形成。(2).本研究所建立的硬化牙本質模型與自然硬化牙質有相似的顯微結構及組成。(3).目前建立之人工硬化牙本質模型在微拉伸黏著強度低於健康牙本質,高於自然硬化牙本質。 The common artificial dentin models used for in vitro adhesive studies can be classified into two categories: the chemical-pH cycling model and the biofilm model. The chemical-pH cycling model executes different pH values to simulate the demineralization and remineralization of caries initiation process. However, it’s a tough work to mimic the real progress of caries, cervical abrasion, abfraction, attrition or erosion. When restoring teeth with these lesions, we always have to face the challenge of sclerotic dentin which was filled with Mg-β-tricalcium phosphate crystals in dentinal tubules microscopically. Up to now, there is no artificial dentin model can mimic these crystals in the dentinal tubules. Thus, we aimed to simulation the artificial sclerotic dentin model and test with in vitro bond strength test. This study was carried out in three parts, Part I: To investigate the microstructure and compositions of natural sclerotic dentin. Part ΙΙ: To establish an artificial sclerotic dentin model with the simulation of natural sclerotic dentin, growing the crystal inside dentinal tubules. We proposed an appropriate formulation and explore the crystal length, compositions and mechanisms in of the intratubular crystals. The porosity and mineral density were also evaluated by non-destructive nano-CT for comparing with natural sclerotic dentin and sound dentin. Part ΙIΙ: To perform the micro-tensile bonding strength (μ-TBS) of the dental adhesive with artificial sclerotic dentin, natural sclerotic dentin and sound dentin. The results revealed that the rhombus intratubular Mg-tricalcium phosphate crystals in natural sclerotic dentin were formed to tight correlation with collagen fibrils inside the dentinal tubules. In the artificial sclerotic dentin model, crystals in dentinal tubules were detected as OCP (octacalcium phosphate)-like crystals. The growth depth was more than 500 μm and direction of crystal growth was from the surface of peritubular dentinal wall inward the center of dentinal tubule. The initial crystallization was in contact with the peritubular dentin with smaller crystal size. The dentinal tubules were completely occluded by accumulating crystals later on. Porosity evaluation with nano-CT showed similar results of artificial and natural sclerotic dentin around the 50 μm superficial region. The mineral density in artificial sclerotic dentin was slightly higher than the natural sclerotic dentin, and also demonstrated lower μ-TBS than sound dentin (25.8±8.1 MPa vs. 30.9±7.6 MPa, p>0.05). Based the limited results, we concluded that: (1) Natural sclerotic dentin was formed via a “bio-de and -re-mineralization” process. (2) The simulated artificial sclerotic dentin model in our study showed similar micro-/ ultra-structure and compositions. (3) The μ-TBS of artificial sclerotic dentin was lower than the sound dentin which can be applied for further adhesive investigation of standardized model. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/74283 |
DOI: | 10.6342/NTU201903273 |
全文授權: | 有償授權 |
顯示於系所單位: | 臨床牙醫學研究所 |
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