Er,Cr:YSGG 雷射製備牙本質窩洞之形態分析及複合樹脂填補後鍵結關係之探討

Dentin Bonding after Cavity Preparation Using Er,Cr:YSGG Laser

林伯彥(Po-Yen Lin)

指導教授 ： 藍萬烘

共同指導教授 ： 林俊彬(Chun-Pin Lin)

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01714

摘要

在牙科復形領域中，由於傳統高速磨牙基的使用會使病患感受到震動、擾人的噪音、以及酸痛等等的不適，因此眾多學者皆致力於尋找出更新、更有效率的方法，期能改善這些情形。雷射應用在牙科的發展已經邁入第四十個年頭，近幾年，科學家們發現Er:YAG以及Er,Cr:YSGG這兩種雷射由於其能量很容易被水及氫氧磷灰石（hydroxyapatite）吸收，因此非常適合應用在牙齒的硬組織如窩洞的製備上。而根據研究發現，Er,Cr:YSGG雷射製備過後的牙本質表面沒有碎屑以及塗抹層的堆積，牙本質小管的開口也很清晰地顯露出來，因此可以推測為相當適合複合樹脂填補的介面，然而，關於Er,Cr:YSGG雷射製備過後之牙本質窩洞與複合樹脂之間的鍵結關係，其相關的文獻卻不多，因此，本實驗即以高速磨牙鑽針修形牙本質窩洞作為對照組，利用立體光學顯微鏡與掃瞄式電子顯微鏡做形態之觀察與分析，並進行拉力測試，以研究探討使用Er,Cr:YSGG雷射製備牙本質窩洞，對於牙本質與複合樹脂間黏著關係的影響。

本實驗可分為三部分，第一部份以功率3.5 W、噴水量80%、噴氣量80%的Er,Cr:YSGG雷射以及高速磨牙鑽的cylinder bur #411分別在3 mm厚的牙本質切片上製備牙本質窩洞，之後並分為酸蝕前與酸蝕後兩組進行立體顯微鏡以及掃瞄式電子顯微鏡的觀察。第二部份的實驗，將各組試片窩洞內側塗上黏著劑One Coat Bond (Coltene)，並用複合樹脂（Palfique Estelite Paste）加以填補。固化後將牙齒劈開，將這些試片用HCl以及NaOCl去礦化以及去蛋白質化，以立體顯微鏡以及掃瞄式電子顯微鏡觀察其介面的情形。最後一部份的實驗，利用拉力測試機（INSTRON）測試各組牙本質窩洞與複合樹脂間的tensile bond strength，使用 Kruskal-Wallis及Mann-Whitney兩種統計方法進行分析，之後並以立體顯微鏡以及掃瞄式電子顯微鏡觀察分析斷裂面的形態。

於表面觀察的實驗中，可以見到在Er,Cr:YSGG雷射製備過後的牙本質窩洞，在未經酸蝕的狀態下，其表面的塗抹層皆被移除，構造呈現鱗片狀，且牙本質小管開口的形態清晰可見，此外，可以見到管周牙本質（peritubular dentin）突出於管間牙本質（intertubular dentin）之上，顯示出Er,Cr:YSGG雷射對於管間牙本質具有較強的移除作用。而在劈開觀察介面的部分，則可以看到不論是高速磨牙鑽針或是Er,Cr:YSGG雷射所製備之窩洞，經過37%磷酸酸蝕後之試片都可以見到許多的樹脂突延伸到牙本質小管中，且其基部呈現漏斗狀（funnel-shaped）；Er,Cr:YSGG雷射製備而無酸蝕的試片中，也可以看到多量且長的樹脂突進入到牙本質小管中，而呈現圓柱狀（cylindrical shape）的形態。至於在第三部分的拉力測試實驗中，A組（高速磨牙鑽針並以37%磷酸酸蝕）的tensile bond strength平均為5.37 MPa，B組（Er,Cr:YSGG雷射並以37%磷酸酸蝕）為5.17 MPa，C組（Er,Cr:YSGG雷射無酸蝕）則為3.29 MPa。統計結果顯示A、B兩組之間沒有顯著的差異（p > 0.05），而B、C兩組之間則有顯著的差異（p < 0.05）。在斷裂模式方面，依照光學立體顯微鏡觀察的結果，A組的斷裂模式有5個type 1（adhesive failure）、4個type 2（partial adhesive and cohesive failure）、以及1個type 3（cohesive failure in resin）；B組的斷裂模式有3個type 1以及7個type 2；C組則為7個type 1以及3個type 2。

Er,Cr:YSGG雷射製備後的窩洞可與複合樹脂之間產生良好的鍵結關係，由拉力測試實驗中可以發現，不論是高速磨牙鑽針或是Er,Cr:YSGG雷射所製備之窩洞，在酸蝕過後皆會加強牙本質與複合樹脂間的鍵結關係。由於Er,Cr:YSGG雷射作用在牙本質上的機制目前尚未能完全透徹了解，因此我們還必須進行更多的實驗以及研究，期能在臨床上提供更有價值的應用。

關鍵字

Er,Cr:YSGG雷射 ； 酸蝕 ； 牙本質 ； 掃描式電子顯微鏡 ； 鍵結 ； 混合層

並列摘要

For many years, dentists have used conventional mechanical high speed systems to remove diseased dental hard tissues and prepare cavities for restoration. This process is efficient but uncomfortable for the patient. Therefore, lots of investigators tried hard to obtain a new model to solve these problems. Research concerning dental applications of lasers has been undertaken for more than 40 years. Recently, Er:YAG and Er,Cr:YSGG lasers, with wavelengths corresponding to absorption peaks for water and hydroxyapatite, have been shown to remove dental hard tissue effectively without causing undesirable thermal effects. Based on the literature reviews, the dentin surface after Er,Cr:YSGG laser irradiation was very clean, with patent tubule orifices and lacked of smear layer coverings. So it might be a favorable technique for the removal of carious dentin and cavity preparation, followed by composite resin restoration. However, surprisingly little attention has given to the evaluation of the quality of the Er,Cr:YSGG laser irradiated dentin surface for composite resin bonding. Thus the aim of this study was to investigate bonding between human dentin and composite resins in cavities prepared with an Er,Cr:YSGG laser, compared with high-speed drills. The morphological features of the irradiated dentin after acid etching were also observed.

This study consisted of three parts. The first part compared the morphological analysis of the prepared dentin surface between Er,Cr:YSGG laser irradiation and high speed bur drilling, before and after 37% phosphoric acid etching. The laser was set at 3.0 W with 80% water and 80% air, in non-contact mode. The 2 x 2 mm square and 1 mm deep cavities, which were prepared on approximate 3 mm thick dentin disks, were then observed under light stereoscopy and scanning electron microscopy. The second part of our study was to observe the resin-dentin bonding interfaces. The cavities grouped as the first part were treated with adhesive (One Coat Bond, Coltene®) followed by composite resin (Palfique Estelite Paste) restoration. After splitting, the dentin discs were observed under scanning electron microscopy after dentin-resin interface demineralization (10N HCl) and deproteinization (1% NaOCl). The final component of this study was to estimate the tensile bond strength of the groups just like the above. The INSTRON Universal Testing Machine was chosen with testing speed set at 0.5 mm/min. After test, the data was computed by Kruskall-Wallis statistics and the fracture modes were recorded, followed by scanning electron microscopy observation.

The Er,Cr:YSGG laser beam produced cavities without signs of thermal damage of dentin. Undesirable thermal effects such as surface cracking or carbonization were not observed. In cavities prepared with high-speed drills, resin tags were more frequent and thicker in dentin subjected to acid etching then without etching. Bonding to laser irradiated dentin resulted in more and thicker resin tags in cavities compared with high speed drills; moreover, the removal of intertubular dentin was more prominent than peritubular dentin. Acid etching resulted in hybrid layers that could be detected under SEM observation. The tensile bond strength of the high speed bur preparation after acid etching was 5.37 MPa, which is not significantly different (p > 0.05) to that of Er,Cr:YSGG laser irradiation after acid etching, 5.17 MPa. The tensile bond strength of the Er,Cr:YSGG laser irradiation without acid etching was 3.29 MPa, which is significantly lower (p < 0.05) than the above two. As for the fracture modes, 5 adhesive failures (type 1), as well as 4 partial adhesive and partial cohesive failure (type 2) and 1 cohesive failure in resin (type 3) were noted in the group treated with high speed bur preparation with acid etching. 3 type 1 and 7 type 2 failure modes were in the teeth irradiated with Er,Cr:YSGG laser with acid etching. Without acid etching, 7 type 1 and 3 type 2 failure modes were recorded.

These findings indicated that it is possible to remove dentin using Er,Cr:YSGG laser irradiation with minimal thermal damage. Bonding between resin and dentin after laser irradiation was equivalent to the conventional technique. Further studies should be conducted in order to obtain more information about the characteristics of Er,Cr:YSGG laser irradiated dentin.

並列關鍵字

Er,Cr:YSGG laser ； acid etching ； dentin ； scanning electron microscopy ； adhesion ； hybrid layer

參考文獻

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