Elias Carlos Nelson, Henriques Flavio Queiroz
Materials Science Department, Military Institute of Engineering, Rio de Janeiro, RJ, Brazil.
J Appl Oral Sci. 2007 Feb;15(1):18-23. doi: 10.1590/s1678-77572007000100005.
In clinical practice, loss of adhesion between the silicone-based denture liner and the denture base resin is always an undesirable event that might cause loss of material softness, water sorption, bacterial colonization and functional failure of the prosthesis.
This study evaluated the effect of thermocycling on tensile and shear bond strengths of three soft liner materials to a denture base acrylic resin.
Three resilient liners (Mucopren-Soft, Mollosil-Plus and Dentusil) and a heat-polymerized acrylic resin (QC-20) were processed according to manufacturers' directions. Sixty specimens (14 x 14 mm cross-sectional area) per bond strength test (20 for each liner) were fabricated and either stored in water at 37 degrees C for 24 hours (control groups; n=10) or thermocycled 3,000 times in water between 5 degrees C and 55 degrees C (test groups; n=10). The specimens were tested in tensile and shear strength in a universal testing machine until fracture. Bond strength means were compared between water-stored and thermocycled groups for each material, as well as among materials for each treatment (water storage or thermocycling). Failure mode (adhesive, cohesive and mixed) after debonding was assessed. Data were analyzed statistically by paired Student's t-test and ANOVA at 5% significance level.
The water-stored groups had statistically significant higher bond strengths than the thermocycled groups (p<0.05). Without thermocycling, Mucopren-Soft (2.83 +/- 0.48 MPa) had higher bond strength than Mollosil-Plus (1.04 +/- 0.26 MPa) and Dentusil (1.14 +/- 0.51 MPa). After thermocycling, Mucopren-Soft (1.63 +/- 0.48 MPa) had the highest bond strength (p<0.05).
The bond strength of the three soft denture liners tested in this study changed with their chemical composition and all of them exhibited higher bond strengths than those usually reported as clinically acceptable.
All soft lining materials tested in this study showed a significant decrease in the bond strength to an acrylic denture base resin after thermocycling. In spite of thermocycling, though, the silicone-based liners had satisfactory bond strengths for clinical application.
在临床实践中，硅酮基义齿衬垫与义齿基托树脂之间的粘结丧失一直是不良事件，可能导致材料柔软度丧失、吸水性增加、细菌定植以及假体功能失效。
本研究评估了热循环对三种软衬材料与义齿基托丙烯酸树脂之间拉伸和剪切粘结强度的影响。
按照制造商的说明加工三种弹性衬垫（Mucopren-Soft、Mollosil-Plus和Dentusil）和一种热聚合丙烯酸树脂（QC-20）。为每个粘结强度测试制备60个试样（横截面积为14×14mm）（每种衬垫20个），并将其在37℃水中储存24小时（对照组；n = 10）或在5℃至55℃的水中进行3000次热循环（测试组；n = 10）。在万能试验机中对试样进行拉伸和剪切强度测试，直至断裂。比较每种材料在水储存组和热循环组之间的粘结强度平均值，以及每种处理（水储存或热循环）中材料之间的粘结强度平均值。评估脱粘后的失效模式（粘结、内聚和混合）。数据采用配对学生t检验和方差分析进行统计学分析，显著性水平为5%。
水储存组的粘结强度在统计学上显著高于热循环组（p<0.05）。在未进行热循环时，Mucopren-Soft（2.83±0.48MPa）的粘结强度高于Mollosil-Plus（1.04±0.26MPa）和Dentusil（1.14±0.51MPa）。热循环后，Mucopren-Soft（1.63±0.48MPa）的粘结强度最高（p<0.05）。
本研究中测试的三种软质义齿衬垫的粘结强度随其化学成分而变化，并且它们的粘结强度均高于通常报道的临床可接受值。
本研究中测试的所有软衬材料在热循环后与丙烯酸义齿基托树脂的粘结强度均显著降低。尽管如此，经过热循环后，硅酮基衬垫的粘结强度在临床应用中仍令人满意。
