評估新式組織調理材加入聚甲基丙烯酸甲酯樹脂對黏著強度的影響:體外實驗

Abstract

實驗目的: 評估加入適當比例的聚甲基丙烯酸甲酯 (poly methyl methacrylate, PMMA) 樹脂後是否對新式組織調理材(NTU-TC)與活動義齒基底間的黏著強 度有影響。 材料與方法: 實驗組依照組織調理材比例，依序加入 2.5、5、7.5、10、12.5 和 15 wt%的 PMMA 樹脂共 6 大組於新型組織調理材粉劑中和聚乙基丙烯酸甲酯 (poly ethyl methacrylate, PEMA) 樹脂調和，並和液劑— 78.3 wt%乙醯檸檬酸三丁酯 (acetyl tributyl citrate, ATBC)、8.7 wt%超分支聚酯 (hyperbranched polyester, 簡稱 TAH) 和 13 wt%乙醇以粉液比 1.2 均勻混合。控制組為不加入任何 PMMA 樹脂 的 NTU-TC。依據國際標準 (International Organization for Standardization, ISO) ISO 10139-2:2016 規範和美國材料測試協會 (American Society for Testing and Materials, ASTM) ASTM: D429 Method A 的建議進行抗張黏著強度測試，將每組 組織調理材與常用於活動義齒基底之材料—PMMA 樹脂塊 (Lucitone 199, Dentsply) (尺寸直徑為 30 mm、厚度 30 mm) 進行裝配，組織調理材尺寸固定為 截面積 7.07 cm2、厚度 3 mm，以兩塊樹脂塊似三明治般黏著成一受試樣品，接著 模擬口腔環境於不同天數下之 37±1°C蒸餾水中浸泡 (依據浸泡時間分成第 0、1、3、7、14、28 天共 6 小組)，並用萬用測試儀 (universal testing machine) 以 10 mm/min 速率拉開進行抗張黏著強度測試 (tensile test) 以及紀錄抗張黏著強度數 值 (tensile bond strength value)。每小組需 10 個樣品 (n=10)，共計 420 個樣品。 統計方式使用雙因子變異數分析 (two-wayANOVA)、單因子變異數分析 (one- way ANOVA)，再以 Tukey HSD 法作事後比較檢定 (post-hoc test) ，有意義水準 設於 p≤0.05。以肉眼和立體顯微鏡觀察試驗後黏著失效模式 (failure mode) 並記 錄。 實驗結果: 在第 0-28 天間，添加不同比例 PMMA 樹脂的 NTU-TC 和活動義齒基 底 PMMA 樹脂間的平均抗張黏著強度數值，同組間隨著浸泡時間的增加除了控 制組 (p=0.126) 以外都有顯著增加的趨勢 (p≤0.05);各組間加入 7.5 wt% PMMA 樹脂的組別測試結果顯示在第 0 天至第 28 天的平均抗張黏著強度數值均為最 高，和控制組相比，加入 7.5 wt% PMMA 樹脂組別的抗張黏著強度數值，隨著浸 泡時間的增加，除了第 3 天 (p=0.120) 以外都有顯著增加的趨勢 (p≤0.05)。有關 失效模式分析，各組材料都有出現膠合面失效 (adhesive failure) 和混合失效 (mixed failure) 的情況。整體而言，發生混合失效者較多，佔 53.3%，而膠合面失 效佔 46.7%。 結論: 添加不同比例的 PMMA 樹脂和浸泡水中的時間這兩項因素都會對 NTU-TC 和活動義齒基底 PMMA 樹脂間的抗張黏著強度有影響。在第 0-28 天間，加入 2.5-15 wt% PMMA 樹脂均能使 NTU-TC 與活動義齒基底間在 14 天內達到臨床需 求的黏著強度;然而並非隨著添加的 PMMA 樹脂愈多, 黏著強度會增加愈多，其 中以加入 7.5 wt% PMMA 樹脂的組別有最顯著的黏著效果。而自 14 天至 28 天的 觀察期間，加入 5 wt% 的 PMMA 樹脂或是 7.5 wt% 的 PMMA 樹脂都能有效增 加抗張黏著強度而改善 NTU-TC 的黏著強度，使其高於市售產品 Lynal 的黏著強 度。模擬口腔環境下 28 天，所有組別的抗張黏著強度均隨著浸泡水中時間的增 加而有增加的趨勢。各組組織調理材都有出現膠合面失效和混合失效的情況，推 測是添加 PMMA 樹脂之後的聚合物不均質，部分界面因為材料吸水膨脹而分 離，呈現膠合面失效，部分界面因為 PMMA 樹脂使黏著性質增強而超過材料本 身抗撕裂能力、伴隨剪切力量的介入而呈現膠合體失效。然而，本實驗並未觀察 到隨著浸泡天數的增加或添加 PMMA 樹脂比例的增多而趨向膠合面失效或是膠 合體失效的情形。

Objective: This in vitro study was to evaluate the effects of adding poly(methyl methacrylate) (PMMA) resin into a new type tissue conditioner (named as NTU-TC) on its bond strength to PMMA denture base resin. Materials and Methods: This study included six experimental groups (n=10) according to the amount of PMMA added. 2.5, 5, 7.5, 10, 12.5, and 15 wt% PMMA were added to poly(ethyl methacrylate) (PEMA) powder and mixed with the liquid consisted of 78.3 wt% acetyl tributyl citrate (ATBC), 8.7 wt% hyperbranched polyester (TAH), and 13 wt% alcohol by powder/liquid of 1.2. The original NTU-TC with 100wt% PEMA was used as the control group for comparison. According to the methods introduced by ISO10139-2:2016:7.3 and ASTM: D-429, each cylinder samples consisted of two resin blocks (diameter of 30 mm x thickness of 30 mm) and the tested tissue conditioner (with 7.07 cm2 cross-sectional area x 3 mm thickness) placed between the blocks sandwichedly. After immersion in the distilled water at 37±1°C in the simulations of oral environment for 0, 1, 3, 7, 14, and 28 days, the tensile bond strength was examined using a universal testing machine at a crosshead speed of 10 mm/min. The peak force was recorded. The data were analyzed using two-way ANOVA, and one-way ANOVA with Tukey HSD post hoc test. The p value ≤ 0.05 means stastically significant. The failure mode was also observed with visual examination and stereomicroscope, and was recorded as adhesive, cohesive or mixed failure. Results: From Day 0 to Day 28, the mean tensile bond strength value of all groups except the control group (p=0.126) significantly increased with immersion time (p≤0.05). Addition of 7.5wt% PMMA to the NTU-TC showed the highest mean tensile bond strength value, which were 0.416 ± 0.050, 0.480 ± 0.065, 0.499 ± 0.059, 0.545 ± 0.057, 0.601 ± 0.047, and 1.452 ± 0.317 MPa at the day of 0, 1, 3, 7, 14 and 28 individually. The mean tensile bond strength value of the control group was 0.353 ± 0.052, 0.348 ± 0.069, 0.424 ± 0.069, 0.425 ± 0.080, 0.495 ± 0.082 and 0.612 ± 0.055 MPa individually. Compared to the control group, significantly higher mean tensile bond strength was observed in the 7.5 wt% PMMA group from Day 0 to Day 28 (p≤0.05) expect Day 3 (p=0.120). Regarding to the failure mode, all the groups showed both adhesive failure and mixed failure. The proportion of mixed failure (53.3%) was higher than that of adhesive failure (46.7%). Conclusions: Within the limitation of this study, the tensile bond strength of all groups increased with increasing immersion time form Day 0 to day 28. Adding 7.5 wt% PMMA resin to the powder of NTU-TC showed a maximal increase on the tensile bond strength to PMMA denture base resin within 28 days. We think the new tissue conditioner (NTU-TC) had suitable bonding property with addition of proper amount and proportion of PMMA resin.