In the face of limited success with these modifications, glass-iononmer compositions were promoted for less demanding applications, such as liners, bases, cements, cores, and root canal filling materials, rather than as restorative materials. During the 1980s the utilzation of glass ionomers for such applications increased. How ever, glass ionomers were plagued by technique sensitivities due to mixing requirements, potential problems with postoperative sensitivity , and the need for moisture protection to prevent surface degradation before the secondary setting reaction was completed. With careful attention to procedural details, glass ionomers have proven clinically successful in many applications. However, in restorative filling applications, glass ionomers have never been as esthetic as composites.