磷酸三鈣及羥機磷灰石基底之光聚合式活髓治療生物材料之發展

Development of tricalcium phosphate (TCP) and hydroxyapatite (HA) based light-cured biomaterial for vital pulp therapy

林君諺(Chun-Yen Lin)

指導教授 ： 陳敏慧

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104249

摘要

近年來牙科活髓治療越趨普及，在牙髓暴露齲齒處理的治療選擇除了根管治療之外還有其他可能性。活髓治療原本較常使用於乳牙齒列，但隨著近年來材料的發展，在成人齒列之成功率也提高了許多。儘管活髓治療之成功率和牙齒本身之初始狀況有最大的相關，但使用的活髓治療材料也有很大的影響，近年來較常使用成功率較高的活髓治療材料有mineral trioxide aggregate (MTA)及生物陶瓷材料像是Biodentine，但現有這些高成功率材料仍有些缺點，像是臨床使用操控性、較長的固化時間、較高的價格及牙齒變色等，而另外一款光聚合式材料Theracal LC解決了長固化時間的問題，但其細胞毒性仍較高不適合作為活髓治療使用。故本實驗目標為評估不同比例混合之低毒性光聚合樹脂材料及填料作為直接活髓治療材料之可行性。
本實驗選用兩種不同的樹脂材料並分為兩大組，A大組使用之樹脂材料為ethoxylated (15) trimethylolpropane triacrylate，並混入不同比例之tricalcium phosphate (TCP)及hydroxyapatite (HA)(分為A0-A5組)，B大組使用之樹脂材料為polyethylene glycol (600) diacrylate，一樣混入不同比例之TCP及HA(分為B1-B5組)。硬度測試(每組n=6)及固化放熱測試(每組n=5)在材料上進行。細胞活性測試及分化測試(Alizarin Red Staining (ARS) assay)利用人類牙髓細胞做體外實驗(每組n=6)，最後再利用B4及B5組別與Biodentine及control組於SD大鼠(Sprague-Dawley rats)之上顎大臼齒做體內實驗，並切片染色觀察。
實驗結果發現硬度部分各組結果均介於4至7 HV之間，和現行市售活髓治療材料MTA或Biodentine相比顯著低許多；而聚合時溫度上升量在B4及B5組(有加入較高比例之去離子水)皆少於5度C，其餘光聚合材料組別均上升超過11度C，有60%可能性造成牙髓之不可逆損傷；牙髓細胞活性測試部分僅第1天之B4組顯著低於B5組及control組，第3天、第7天各組間皆無顯著差異；牙髓細胞分化實驗部分在未加分化配方的部分到了第10天時B5及Biodentine組顯著高於B4及control組，相較於第4、7天也有顯著較高；大鼠體內實驗部分可以在第三週及第六週之Biodentine及B5組別觀察到較明顯之礦化生成，Biodentine組在第六週時無觀察到發炎情況，B5組則是在第三週及第六週皆無發現發炎情況。
由本實驗結論可知，本實驗材料因硬度不高，外層仍需高抗磨耗高硬度之材料進行窩洞復形。B4及B5材料之溫度上升量在安全範圍內，不用擔心牙髓產生不可逆損傷。而B5材料對於牙髓細胞幾乎無毒性，且發炎反應結束時間相較於Biodentine更快，也和Biodentine一樣可以誘導牙髓組織產生礦化，而其相較於Biodentine之優點為臨床使用時有更快的固化時間。

關鍵字

活髓治療 ； 活髓治療材料 ； 光聚合樹脂活髓治療材料

並列摘要

Vital pulp therapy (VPT) is used to maintain healthy pulp tissue through elimination of bacteria from the dentin-pulp complex and is a potential alternative to root canal treatment. It has been commonly performed in primary dentition, but with the recent development of material, the survival rate is also very high in secondary dentition. Although the success rate of VPT is mostly dependent on the status of the pulp tissue, the material used for VPT is also a major factor. Recent studies have demonstrated that mineral trioxide aggregate (MTA) and bioceramics such as Biodentine are commonly used for VPT in permanent dentition with high success rates. Although these two materials are highly biocompatible, some of these materials still have disadvantages such as difficulty in handling, long setting time, high cost, and may cause tooth discoloration. Other light-cured materials with decreased setting time, such as Theracal, may instead be cytotoxic to dental pulp cells. Therefore, the purpose of this study is to develop a new light curing material for shortening the setting time with low cytotoxicity for vital pulp therapy.
Two different resin materials were selected as the base material and separated into two groups. Group A consisted of ethoxylated (15) trimethylolpropane triacrylate mixed with different ratios of tricalcium phosphate (TCP) to hydroxyapatite(HA) (subgroups A0~A5), while group B consisted of polyethylene glycol (600) diacrylate mixed with different ratios of TCP to HA (subgroups B1~5). The hardness (n=6 for each subgroup) and temperature change (n=5 for each subgroup) were tested on the materials. Cell viability and Alizarin Red Staining (ARS) assay were tested in vitro on human dental pulp cells (n=6 for each subgroup). Lastly, B4 and B5 groups were then compared with Biodentine and control groups in the molars of Sprague-Dawley (SD) rats in vivo for histology assessment. According to the invitro results, both B4 and B5 groups were demonstrated with less temperature change after setting and were selected for further in vitro studies.
Results demonstrated that the hardness of all materials to be within 4 to 7 HV. This hardness is significantly lower compared to the hardness of MTA or Biodentine. The temperature change for groups B4 and B5 were both under 5 degrees Celsius. For the in vitro assessments, cell viability of B4 on day 1 was significantly lower than B5 and control groups, but no significant difference was seen on day 3 and day 7. Alizarin Red Staining (ARS) assay showed significantly higher mineralized nodule formation when treated without induction medium for B5 and Biodentine groups on day 10 compared to B4 and control groups. B5 and Biodentine groups treated without induction medium were also significantly more mineralized on day 10 compared to those on day 4 and day 7. Histology assessments demonstrated higher mineralized content in B5 group and Biodentine group on week 3 and week 6. The inflammatory cells in the dental pulp complex of the Biodentine group resolved on week 6 while the inflammation resolved in Group B5 on week 3.
According to the results, TCP HA based light cured biomaterial is suitable for vital pulp therapy. The cytotoxicity of the B4 and B5 groups is low and the temperature change after setting is also less than 5°C, which are biocompatible with dental pulp cells. B4 and B5 groups can also induce mineralization of dental pulp tissue similar to the effects of Biodentine, but has the advantage of a shorter setting time compared to Biodentine. Although both TCP and HA light cure biomaterials in groups B4 and B5 are suitable for vital pulp therapy, the hardness is low and might not be suggested for direct restoration.

並列關鍵字

Vital pulp therapy ； Vital pulp therapy material ； Light-cured resinous vital pulp therapy material

參考文獻

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