RESTORATIVE MATERIALS BASED ON SILSESQUIOXANE POLYMERS

目前的聚合物牙科修复复合前体在过去的25年里基本保持不变。这些材料有几个缺点，包括(a)需要大量的填充剂来提高机械强度，(b)不完全固化，(c)收缩，(d)长期的附着力退化。为了克服这些限制，必须在全新的候选材料方面取得进展。我们建议使用公式为[(SiO1.5)8(OR)x(OSi[CH3]2R‘)8-x]的硅氧烷杂化单体，其中R是短烷基链，R’是可聚合的基团，如环氧环或环键烯烃。这些材料的特点是刚性（SiO1）的组合。5)8核心（赋予强度和稳定性）与两个独立的反应基团：-OR，它是水解敏感的，与结合在牙本质表面的水分子反应；R'，用于强体聚合。其他好处包括易于加工，减少对无机填料的依赖，以及增加对口腔环境的抵抗力。我们第一阶段的目标是证明这些材料的潜力：(1)相关硅氧烷单体的合成和表征；（二）养护性能的确定；(3)力学性能评价；(4)研究与纳米相氧化物（如TiO2、ZrO2）的相容性对美容效果的影响；(5)口腔环境耐久性的初步模型研究。在第二阶段，我们将通过反复的结构/性质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高级粘合剂。

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.