添加不同比例的成孔劑對於氧化鋯材料性質及樹脂黏著強度的影響

Abstract

氧化鋯（Zirconia oxide）因其強度特性，牙科早期多應用於全陶瓷支架；但近年隨著釔安定氧化鋯（Yttria –stabilized tetragonalzirconia polycrystalline, YTZP）發展，除了大幅度增加氧化鋯以強度更強的立方晶相(tetragonal phase)在室溫穩定存在，而非純氧化鋯的單斜晶相（Monoclinic phase）；還增加陶瓷的透度，使得氧化鋯開始能夠兼具耐受口腔咀嚼的使用強度、以及仿生美學需要的光線透射質感。 然而氧化鋯的粘著強度穩定性以及表面處理，相對於長石類的陶瓷來的較弱而且流程複雜許多。目前的黃金標準是使用噴砂法（Sandblasting）：以0.2 MPa高壓空氣，噴出粒徑為50 μm氧化鋁細粒撞擊，增加表面的粗糙程度以利粘著。但此法可能造成微觀的陶瓷裂痕，以致部分的立方晶相晶體轉變成為單斜晶相，造成日後容易受力裂開。而且過度噴砂也會造成黏著力下降。 因此本實驗為自行調配氧化鋯漿料，參雜不同比例的成孔劑，燒結成型後，料塊如蜂巢狀，形成內外的孔洞以及粗糙表面，替代噴砂法對氧化鋯陶瓷表面可能的物理傷害，並節省臨床的操作時間，製作更為深入的連續孔洞，造成更好的黏著劑浸潤效果，增加顯微機械附著的強度。實驗以市售常用的3M Single Bond Universal、RelyX Ultimate、Z350 Light- cured Resin為黏著材料。 由系列實驗：表面粗糙度測試（Surface roughness test）：確認表面粗糙度的數值；剪切應力黏著測試(Shear bonding strength test)：利用萬能材料試驗機，確認樹脂黏著劑與不同粗糙程度的氧化鋯表面，受到剪切應力（Shear force）的大小變化；X光繞射分析（X-ray diffractometer, XRD）：檢查前後晶體型態的變化；電子顯微鏡攝影（Scanning Electron Microscope , SEM）：直觀的檢視受力實驗前後，不同粗糙度的氧化鋯表面與截面型態；表面孔隙比例：藉SEM圖片，給予孔隙率與黏著力關係的量化比較。 結果顯示，隨著成孔劑參雜率由0%開始增加，平均黏著強度隨之增加，到40%參雜率為最大值，該組別黏著力顯著大於0%組別；60%參雜率的平均粘著強度反而下降。代表成孔劑參雜率40%的氧化鋯表面粗糙狀況，是最適合樹脂粘著的組別。 日後發展3D列印氧化鋯的漿體時，可以此成孔劑參雜比率做為參考基準，由此進行更深的討論。

Zirconia oxide has long been utilized in dentistry primarily for all-ceramic frameworks due to its strength characteristics. However, recent advancements in yttria-stabilized tetragonal zirconia polycrystalline (YTZP) have significantly increased zirconia's ability to maintain its stronger tetragonal phase at room temperature, as opposed to the monoclinic phase of pure zirconia. Additionally, these developments have enhanced the ceramic's translucency, allowing zirconia to combine both the required chewing strength within the oral cavity and the aesthetic need for lifelike light transmission. Nevertheless, clinicians have faced challenges regarding zirconia's adhesive strength and surface treatment, which are comparatively weaker and more complex than those of feldspathic ceramics. The current gold standard involves sandblasting, using 50 μm alumina particles at 0.2 MPa to increase surface roughness for improved adhesion. However, this method may induce microscopic ceramic cracks and lead to partial transformation of tetragonal phase crystals into monoclinic phase, rendering them susceptible to fracture under stress. Moreover, excessive sandblasting can reduce adhesive strength. To address these issues, this experiment involved formulating zirconia slurries with varying proportions of pore-forming agents. After sintering, the resulting blocks exhibited a honeycomb-like structure with internal and external pores and rough surfaces, aiming to replace sandblasting and mitigate potential physical damage to zirconia ceramic surfaces. This method also aimed to save clinical operation time and create more profound continuous pores, thereby enhancing adhesive wetting and micro-mechanical attachment strength. The experiment utilized commonly available adhesive materials: 3M Single Bond Universal, RelyX Ultimate, and Z350 Light-cured Resin. Through a series of experiments, including surface roughness tests, shear bonding strength tests, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) imaging, and porosity comparison, results demonstrated that adhesive strength increased with the incorporation of pore-forming agents up to a 40% rate, with a subsequent decline at 60%. This suggests that a 40% incorporation rate of pore-forming agents is optimal for zirconia adhesion. In future developments of 3D printing zirconia pastes, this optimal pore-forming agent incorporation rate can serve as a reference benchmark for further discussion.