從18世紀以來，人類便懂得使用氟化物預防齲齒，雖然科學家對於氟離子抗齲機制尚未完全明瞭，但如今越來越多報導顯示，長期使牙齒周遭唾液含低濃度氟離子是最有效的抗齲方法。研發出能夠釋放氟離子之牙科修復物是當今熱門的研究方向，但此領域之研究大多著重於溝隙封填劑之改質，尚未有人將此法運用於瓷牙冠。瓷牙冠失效的原因有50 %是源自於二次齲齒，若瓷牙冠最外層之牙瓷釉藥能夠長期釋出氟離子預期將能減少二次齲齒的問題。
本研究欲藉由改質釉粉來降低瓷牙冠下的真牙發生齲齒的機率，但於此同時，改質釉粉所燒製出的釉層試樣也需有足夠的透明度、光滑度及硬度，如此才適用於臨床。本研究以1 wt%、5 wt%和10 wt%氟化鈉熔入商用牙科釉粉，探討各釉粉試樣之氟離子含量、氟離子釋放量及其微觀結構之變化，並藉由提升燒釉溫度及燒製時間，探討不同的改質釉粉及燒釉流程對燒製出的釉層之粗糙度、氣泡含量、微硬度及色澤之影響。研究結果顯示以5 wt%氟化鈉混入商業牙科釉粉，於650 ℃煆燒2小時再於1000 ℃熔融2小時所得之改質釉粉較少氟離子與氫化合成氟化氫而逸散，故其殘存的氟含量最高，氟離子釋放量亦最多；釉粉微觀結構顯示隨氟化鈉添加量越多其網狀交連度越低，釉粉的軟化點也隨之降低。商用牙科釉粉及以1 wt%、5 wt%和10 wt%氟化鈉熔製之改質釉粉之軟化點分別為685 ℃、678 ℃、635 ℃和543 ℃。
在釉層的性質方面，燒釉溫度由820 ℃提升至900 ℃並持溫15分鐘將減少釉層表面粗糙度；5 wt%和10 wt%氟化鈉熔製之改質釉粉以900 ℃並持溫15分鐘的燒釉流程燒製將能得到氣泡最少之釉層試樣；諸改質釉粉以兩種燒製流程所燒製出之釉層試樣其微硬度皆略低於原始釉粉以820 ℃所燒製出之釉層；5 wt%和10 wt%氟化鈉熔製之改質釉粉以820 ℃燒製將會碳素殘留導致釉層色澤偏黑，若燒釉溫度提升至900 ℃並持溫15分鐘碳素含量將顯著減少而可得到透亮之釉層試樣。
總的來說，5 wt%氟化鈉熔製之改質釉粉以900 ℃並持溫15分鐘的燒釉流程燒製出的釉層最符合本研究的目的。

The objectives of this study had two (a) decreasing the secondaries anti-caries probability of monolithic zirconia crown and (b) obtaining smooth and transparent glaze. To achieve the first objective, the strategy was to modify glaze powders and made it able to release more fluoride ions. As for the second objective, the strategy was adjusting the firing process of manufacture’s suggestion. Modified glaze powders were fabricated by mixing 1, 5 and 10 wt% sodium fluoride with commercial glaze powder. These mixture powders were calcined at 650 ℃ for 2 h and then melted at 1000 ℃ for 2 h to make them become amorphous and homogeneous glaze frits. These glaze frits were ground and sieved to form modified glaze powders. These modified glaze powders were fired by two kinds of firing processes. Original firing process was firing at 820 ℃, and the adjusting one was firing at 900 ℃ and holding for 15 minutes. The fluoride release amounts, roughness and transparency were measured by fluoride ion selective electrode, surface roughness measuring instrument, and colorimeter. The microstructure and crystal structure were observed by SEM and XRD. The results indicated that the modified glaze powders were amorphous, and 5NaF glaze powder released the most amount of fluoride ions. Adjusting firing process would obtain smoother and more transparent glaze than original firing process. To sum up, 5NaF 900 glaze sample had better anti-caries effect and its surface was smooth and transparent, simultaneously.

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