Fracture resistance and failure modes of endocrowns constracted with different materials

Abstract

AbstractPurpose: The purpose of this in vitro study is to compare the fracture resistance andmodes of fracture or failure between different endocrown restoration materials as lithiumdisilicate ceramic (IPS e max press) and indirect composites (Solidex &Gradia)performed for endodontically treated mandibular molars.Materials and Methods: Forty sound human mandibular first molars (N =40, n = 10 pergroup) were selected and randomly divided into four groups.Group1was left intact(control). Group 2 endodontically treated teeth (ETT) restored with endocrown made oflithium disilicate ceramic (IPS e.max press, Ivoclar Vivadent, Schaan, Liech-tenstein).Group 3: ETT restored with endocrown made of Solidex indirect composite (Shofu inc.Japan) Group 4: ETT restored with endocrown made of Gradia indirect composite (GCCorporation, Japan).Fracture resistance (N) was measured using a universal testingmachine. Load was applied parallel to the long axis of tooth till failure. Fractures orfailures were divided into two groups repairable (favorable) and irrepairable(unfavorable). The mean loads of fracture of each group were statistically comparedusing ANOVA p<0.001.Results: The mean fracture strength (N) of IPS e.max group had significantly highermean fracture resistance value (3320±961) when compared to Solidex (2222±938) andGradia (2366±420) indirect composite groups. There was no significant differencebetween mean fracture resistance of Solidex composite and Gradia composite groups.As regard to failure modes the results showed that 80% of the Solidex composite groupsexhibited repairable failure, also that 60% of Gradia composite groups exhibitedrepairable and only 10% of IPS e.max press group exhibited repairable failure.Conclusions: The lithium disilicate ceramics endocrowns exhibited higher fractureresistance when compared to indirect composite endocrowns. Indirect compositeendocrowns exhibited more repairable failure mode when compared to lithium disilicateceramics endocrowns.