Objectives: The aim of this retrospective clinical study was to evaluate the performance of high-viscosity glass-ionomer cement (GIC) class-II restorations over 6 years of clinical service.
Methods: All class-II GIC restorations made in 1996 and 1997, in regular attending adult patients of a general dental practice were selected. Restorations made for temporary function were excluded, as were those restorations not made using the main study material: Fuji IX GP (GC). Failures were recorded where replacement or repair had occurred. Radiographs were evaluated where available.
Results: The final study group consisted of 116 class-II restorations in 72 patients (33 males, 39 females). Distribution of restorations was: 30 MO, 40 DO, 46 MOD. Until 18 months no failures were observed. From 18 to 42 months survival dropped to 93%. After 42 months failure rate increased and at 72 months survival was only 60%. In all but one case the recorded reason for replacement or repair was gross loss of GIC in proximal areas. No restorations failed because of occlusal wear or isthmus-fractures. On radiographs, progressive loss of GIC material in proximal areas, just below contact areas, was commonly observed. In absence of adjacent teeth no loss of GIC material was observed at proximal surfaces.
Significance: Rising failure rate of class-II high-viscosity GIC restorations, due to proximal breakdown was observed. We hypothesize that caries-like loss of material as seen on radiographs contributes to this phenomenon. Presence of proximal contacts seems to promote disintegration of cement.