Cattani-Lorente M A, Godin C, Meyer J M
Laboratory of Dental Materials, School of Dentistry, University of Geneva, Switzerland.
Dent Mater. 1994 Jan;10(1):37-44. doi: 10.1016/0109-5641(94)90020-5.
The early strength of glass ionomer cements was investigated previously (Cattani et al., 1993). Using the same set of glass ionomer cements, this study was designed to determine if mechanical property degradation occurred after an extended period of storage in water.
In the present study, the effect of aging in water on the compressive, tensile and flexural strengths of twelve commercial glass ionomer cements was evaluated at different time intervals after the beginning of the setting reaction. The aging periods varied from 24 h to 12 mon.
The results show that the mechanical properties of the tested materials are in some cases affected by long-term aging in water. The evolution of strength follows distinct patterns of change. It has been established that the glass ionomer cements are neither characterized by a continuous increase nor a continuous decrease in strength. Most of the materials tested maintained a constant strength. However, several of them first display an improvement of the mechanical strength followed by a reduction. In this case, the 24h and the 12 mon strengths are usually similar.
The aging mechanisms of glass ionomers are complex. Strengthening probably results from additional crosslinking and build-up of a silica gel phase, whereas weakening may result from erosion and plasticizing effect of water.
玻璃离子水门汀的早期强度已在之前进行过研究（卡塔尼等人，1993年）。本研究使用同一组玻璃离子水门汀，旨在确定其在水中长期储存后是否会发生机械性能降解。
在本研究中，评估了12种市售玻璃离子水门汀在凝固反应开始后的不同时间间隔下，水老化对其抗压、抗拉和抗弯强度的影响。老化时间从24小时到12个月不等。
结果表明，在某些情况下，测试材料的机械性能会受到水中长期老化的影响。强度的变化遵循不同的模式。已经确定，玻璃离子水门汀的强度既不会持续增加也不会持续降低。大多数测试材料保持恒定强度。然而，其中一些材料首先表现出机械强度的提高，随后降低。在这种情况下，24小时和12个月时的强度通常相似。
玻璃离子水门汀的老化机制很复杂。强度增加可能是由于额外的交联和硅胶相的形成，而强度减弱可能是由于水的侵蚀和增塑作用。
