- 學位論文
以顯微拉力測試及雷射熱解音洩技術來評估牙本質黏著系統之界面接合性 質
Interfacial evaluation of dentin bonding systems by microtensile test and laser thermoacoustic technique
摘要
中文提要: 牙本質黏著強度的傳統機械測試，只能巨觀地獲得斷裂時數 值， 既無法瞭解界面真實情況，且不能觀察斷裂過程及實時破裂模式。 顯 微拉力測試可縮小界面缺陷的影響並直接觀察微小界面，但仍不能實 時觀察破裂過程。 由於感測器及高速資料擷取系統的發達，一種用 來 研究複合材料中各部份接合狀態的技術?p射熱解音洩技術(Laser Acoustic Emission Thermal Technique，簡稱LAETT)已逐漸發展成熟， 其原理是以雷射當熱源，照射於複合材料系統上，引發界面的熱應力 變 化而造成材料內及界面間的斷裂或鍵結解離，進而產生一些音洩訊 號( Acoustic Emission，簡稱AE)。若AE是檢測牙本質黏著系統的有 效工具 ，則75%酒精老化黏著系統的結果(兩者具相近的溶解參數)亦 是值得觀 察。本研究以顯微拉力測試及LAETT測試所得到的資料做 比較，來研究 牙本質黏著系統之界面接合性質。 製作純黏著劑(Optibond、 Scotchbond MP、Tenure)、黏著劑/牙 本質及純牙本質三種試樣(2.5mm 長x 2.5mm寬x 0.25mm厚)，進行 LAETT測試；加上同廠牌樹脂複合材做 成界面面積為1.7mm2的試樣 來進行顯微拉力測試。測試前所有試樣皆浸 泡於37蚓 75%酒精中達 0、2、4、8、24、48小時。 LAETT實驗採用具連 續波的CO2雷 射當熱源產生0.5、1、1.5、2 watt四種不同功率(可經由 分光鏡及 功率測試器得知並校正)去照射試樣，產生的音洩訊號則以高 靈敏度 的感測器接收，經前置放大器(具40dB放大率與100-300 KHZ帶通 濾 波範圍)送入主系統(AEDSP卡，具20dB放大率與10-1200 KHZ帶通濾 波範圍)，將類比電壓訊號轉換成數位訊號，如hit、count、energy 和 amplitude。傳統機械力學與熱音洩實驗結果均配合掃描式電子顯 微鏡 觀察來綜合討論黏著系統之界面性質。 顯微拉力測試所得抗張強度 值比傳統的大30%-100%，表示缺陷少 時，測試值較接近真實，且 Optibond≒Scotchbond MP﹥Tenure。 與其他兩者相較，Tenure系統易 被75%酒精催老化，與其primer成 分的溶解度有關。含填料且樹脂栓深 且長的Optibond系統與不含填料 且樹脂栓寬且短的Scotchbond MP系統 抗張強度竟相差不多，應與操 作步驟有無符合材料強度梯度有關。 在 LAETT方面，Optibond與 Scotchbond MP的界面訊號在60dB以上，而 Tenure則在45-50dB之 間(振幅(dB)大小代表可承受能量的高低)，表示 Tenure界面結合能小 於另二者；而Tenure在1 watt時界面已全裂，而另 二者在1.5watt才 開始裂，亦可証明Tenure界面承受熱應力的能力遠不 及Scotchbond MP及Optibond，此結果與顯微拉力測試結果相符。 雷射熱解音洩技術似乎可成為評估牙本質黏著系統之界面性質的 有效輔 助工具。 英文提要: Traditional mechanical tests of dentin bonding systems can only determine certain mechanical values in a macroscopic observation. It cannot reveal the real conditions of interface and fracture processes . Microtensile tests can directly focus on the effect of interfacial defects and observation, but cannot exactly duplicate a real-time observation . Due to the development of data acqusition systems, a new technique called Laser Acoustic Emission Thermal Technique has been successfully used to study the interfacial bonding status in epoxy-based composites. Laser heating of dentin bonding systems will produce acoustic emission (AE) which may be related to fracture in dentin bonding systems. Storage in a food simulating liquid, i.e, 75% ethanol, having a solubility parameter approximating that of Bis-GMA resin, has been shown to dramatically affect its mechanical properties. If AE is an effective tool for monitoring fracture processes in dentin bonding systems then the systems' response to storage in 75% EtoH should be of interest. In this study, a microtensile test and laser- induced acoustic emissions of ethanol-aged dentin bonding systems were studied to evaluate the interaction of interface (hybrid layer) of dentin bonding systems. Dentin bonding systems (Optibond，Scotchbond MP，Tenure) were fabricated into pure bonding agent，pure dentin and bonding agent/dentin (2.5mm Length x 2.5mm width x 0.25mm thick) for LAETT testing . The same commercial resin composites were used for microtensile test with 1.7mm2 interfacial area . Before testing, the specimens for LAETT & microtensile test were soaked in 37蚓 75% EtOH for 0，2， 4，8，24，48 hours. A continuous wave CO2 laser (Ultra Lasertech RFCL-28) was used at several power levels in the range of 0.5，1，1.5 and 2 watt, which can be read and adjusted by a beam splitter and a power meter. Acoustic emission was detected by a high- sensitivity transducer (Model R-30), then filtered and processed by MISTRAS 2001 (Physical Acoustic corp., with built-in 20dB gain and 10-1200 KHz band pass filler). Detected AE signals were converted to digital parameters such as hit， count，energy and amplitude . The fractured surfaces of microtensile test and laser-heated specimens were examined by a scanning electron microscope (Hitachi S-2400, Japan). The results showed that tensile strength of microtensile test is greater (30%-100%) than that of traditional tensile test (Optibond = scotchbond MP > Tenure) . This indicates that testing value is nearer to real conditions with decreasing quantityof defects (due to decreasing bonding surface area). Tenure was weathered severely after ethanol storage ,and this may be related to it's components. Filled Optibond with long- form tag exhibited the similar tensile strength to that of Scotchbond MP (without filler and wide-form tag) ,which may be due to their operation procedure. In LAETT, the acoustic signal released form Optibond and Scotchbond MP testing produced a high amplitude clusterring pattern (60dB) at 0.5 to 2 watt laser power and Tenure generated a lower one (45-50dB). This means that interfacial energy of Tenure system is smaller than that of Optibond and ScotchbondMP systems. Fracture of hybride layer of Tenure occurred in 1 watt, and the others in 1.5 watt and more. This indicates that Tenure is weaker in enduring thermal stress. The results overall corresponde to those of the microtensile tests. Laser-induced AE appears to be a valuable adjunct to conventional mechanical testing.