Evaluation of Fracture Resistance of Endocrowns Fabricated by Two Different Materials of Different Cavity Configurations and Luted with Two Different Luting Cements – an in Vitro Study

Abstract

BACKGROUND:

Clinical success of endodontically treated posterior teeth is determined by the postendodontic restoration. Endocrowns represent a conservative and esthetic restorative alternative to full coverage crownrestorations especially in clinical cases where the coronal hard tissue loss is excessive and inter-arch space is limited.

OBJECTIVES:

The purpose of this in-vitro study is  to evaluate the fracture  resistance  of the  `endodontically` treated teeth with three cavity configurations  restored with two different crown materials  (metal & Composite resin) “Endocrowns”. And the influence of two different luting cements (glass ionomer and resin luting cement)

MATERIALS AND METHODS:

Three freshly extracted  maxillary premolars  were `endodontically`  treated with  conventional  access opening and obturated with gutta-percha by lateral condensation method .Then class-I, class-II-[MO], class-II [MOD] preparations done. Elastomeric impressions were made and the tooth duplicated with auto-polymerizing  acrylic resin and mounted in a polyvinyl chloride (PVC) rings with the help of a surveyor and the specimens are randomly divided into three groups

Metal and composite endocrowns are fabricated  cemented with two different luting cements ie., self-adhesive(GIC) and self-curing dental resin cement.

All the specimens were subjected to static mechanical loading in an universal testing machine with a cross head speed of 20mm/min and scanned  for presence of fracture under scanning electron microscopy.

RESULTS:

The data obtained were statistically analyzed using one way ANOVA and Student‘t’ test. The fracture pattern and failure modes were classified and analyzed with chi square test.

The finding of this study shows that the mean fracture load for Group-I is 2362.65 N; Group-IIis 1703.50 N; Group-IIIis 1635.25 N. The mean fracture load of teeth restored with metal endocrowns were 2680.30N and composite erndocrowns were 2045N. teeth restored with metal endocrowns showed better   with significant difference between metal and composite material of Group-I & Group-IIand no significant difference between themateral of Group-III.

Regarding the modes of failure, the maximum number of favorable fractures was observed in group-Cg, group-Cr and catastrophic failure among the metal endocrown groups.

CONCLUSION:

Within the limitations of this study, it can be concluded that the conventional metal (nickel chromium) alloy can be used to fabricate endocrown restorations. Laboratory processed composite,however can be used in cases with normal to maximum masticatory forces, but should be avoided in para-functional, abnormal situations with very high masticatory force. Regarding the luting agents, GIC can also be used in endocrown situations, but it’s efficacy regarding the retention is to be evaluated.