In vitro study of fracture incidence and compressive fracture load of all-ceramic crowns cemented with resin-modified glass ionomer and other luting agents

Statement of problem. Anecdotal reports based on clinical observation have recently linked resin-modified glass ionomer luting agents with postcementa tion fracture of all-ceramic crowns. Purpose. This study evaluated the fracture incidence of In-Ceram and VitaDu r Alpha porcelain jacket all-ceramic crowns cemented with 5 luting agents ( Fuji I, Fuji Plus, Vitremer, Advance, and Panavia 21) during 2 months stora ge in 0.8% NaCl solution. Material and methods. Fifty human maxillary premolar teeth were prepared fo r each ceramic system and divided into 5 subgroups of 10 teeth to be cement ed with 5 luting cements. Specimens were observed for fracture lines and cr ack initiation at storage times up to 2 months. Incidence of fracture was a nalyzed with Fisher's Exact test. Specimens that did not fracture during st orage were loaded in compression to failure. Failure loads were analyzed by analysis of variance and multiple pairwise comparisons. Results. Only all-ceramic crowns cemented with Advance cement fractured dur ing the 2-month observation period, and porcelain jacket crowns were found to fracture earlier and more frequently than In-Ceram crowns. Cracks initia ted at the crown margin, and multiple crack lines were found as the time of storage increased. In-Ceram crowns were significantly stronger (140 +/- 21 .5 kg) than porcelain jacket crowns (98.6 +/- 17.8 kg) at P < .05. For In-C eram crowns, cement type did not influence failure load while for porcelain jacket crowns, Fuji I (110.5 kg) was significantly higher than Vitremer (8 6.6 kg) at P < .05. Conclusions. For the cements studied, only crowns cemented with Advance cem ent demonstrated fracture during 2-month storage. Results for the true resi n-modified glass ionomer cements do not support anecdotal reports of fractu re of all-ceramic crowns cemented with these materials.