RESTORATIVE MATERIALS BASED ON SILSESQUIOXANE POLYMERS

目前的聚合物牙科修复复合材料前驱体在过去25年中基本保持不变。这些材料有几个缺点，包括(A)需要大量的填料来提高机械强度，(B)固化不完全，(C)收缩，以及(D)附着力的长期退化。为了克服这些限制，必须在全新的候选材料上追求进步。我们建议使用式为[(SiO1.5)8(OR)x(OSI[CH3]2R‘)8-x]的倍半硅氧烷杂化单体，其中R是短烷基链，R’是可聚合基团，如环氧环或环键烯。这些材料的特点是刚性的(SiO1.5)8核(赋予强度和稳定性)与两个独立的反应基团相结合：-OR和R‘，前者对水解性敏感，与牙本质表面的水分子发生反应，后者用于强本体聚合。其他好处包括易于加工，减少对无机填充物的依赖，以及增加对口腔环境的抵抗力。我们第一阶段的目标是展示这些材料的潜力：(1)相关倍半硅氧烷单体的合成和表征；(2)它们固化行为的测定；(3)它们的机械性能的评估；(4)研究它们与纳米氧化物(即，二氧化钛、氧化锆)的美容效果的兼容性；以及(5)它们在口腔环境中耐用性的初步模型研究。在第二阶段，我们将通过迭代结构/性能研究进一步提高这些材料的性能，并对其在临床条件下的行为进行更严格的研究。拟议的商业应用：除了作为牙科修复剂的预期功能外，这些材料还可以应用于其他医疗修复体、纤维基复合材料的基质材料和先进的粘合剂。

Current polymeric dental restorative composite precursors have remained largely unchanged for the last 25 years. These materials have several short- comings including (a) the need for large amounts of filler for mechanical strength, (b) incomplete curing, (c) shrinkage, and (d) long term degradation of adhesion. In order to overcome these limitations, advances must be pursued in totally new candidate materials. We propose the use of silsesquioxane hybrid monomers of the formula [(SiO1.5)8(OR)x(OSi[CH3]2R')8-x], where R is a short alkyl chain and R', a polymerizable group such as epoxy rings or ring-bound alkenes. These materials feature the combination of a rigid (SiO1 .5)8 core (imparting strength and stability) with two separate reactive groups: the -OR, which is hydrolytically sensitive and reacts with water molecules bound to the surface of the dentin, and R', for strong bulk polymerization. Other benefits include ease of processability, reduced reliance on inorganic fillers, and increased resistance to an oral environment. Our Phase I objectives to demonstrate the potential of these materials are (1) the synthesis and characterization of relevant silsesquioxane monomers; (2) the determination of their curing behavior; (3) evaluation of their mechanical properties; (4) study the compatibility with nanophase oxides (i.e., TiO2, ZrO2) for cosmetic effects; and (5) preliminary model studies on their durability in oral environments. In Phase II we will further improve the performance of these materials by iterative structure/property studies and proceed with more rigorous studies on their behavior under clinical conditions. PROPOSED COMMERCIAL APPLICATIONS: In addition to the intended function as dental restoratives, these materials could have applications in other medical prosthetics, matrix materials for fiber matrix composites, and advanced adhesives.