[Compatation study of two posterior composite operation in endodonticaly treated maxillary premolar with mesio-oclioso- distal cavity before and after mounting in a artificial mouth]

ABSTRACT

There are many restorative designs for root canal treated maxillary premolars that each of which have their own advantages and disadvantages. One of this treatments is composite inlay restoration with fiber-reinforced composite which has sufficient retention, strength and acceptable apearence,as well as more compatibibility and less leakage than cast-metal restoration. In this -experimental study, after calculating a sample groups, 72 sound maxillary premolar teeth with the same size were chosen and fixed in acrylic resin so that the CEJ was 2 mm upper than the level of resin. The sample were randomly divided in to six groups of 12. Group 1[positive control] intact teeth. Group 2 [negative control] root canal treated with MOD cavity preparation that had been extended 1 mm below CEJ. Group 3 and 4 root canal treated teeth with MOD cavity preparation for fiber- reinforced [Nulite F] composite inlay using Nulite F2 liner. Group 5 and 6 these groups were prepared in the same way as groups 3 and 4, differing in that, this specimens were restored by 3MP60 composite instead of Nulite F. Following restoration, all specimens was termocycled 500 times. Specimens of groups 1,2,3,5 were loaded by the universal testing machine [Zwick z020, Germany] at speed of 0.5 mm/min. specimens in groups 4 and 6 onset were loaded by artificial mouth 1000,000 times then loaded by universal testing machine. Finally the results were analyzed using ANOVA test and comparasion multiple tests. Average fracture resistance for first group was 2.091 killo nioton, [kn] second group was 0.862kn, third group was 1.577 kn, fourth group was 1.431 kn, fifth group was 1.296 kn and sixth group was 1.170 kn. According to data analysis the deference between first and secovd groups to other groups was significant. Fracture resistance of 3th group with 5 and 6 groups and 4 th group with 6 group have significant deference. Because of increasing of the fracture resistance in endodontically treated teeth that restorated with fiber-reinforced composite [Nulite F] and their significant deference in comparasion with conventional posteror composite [3MP60] as well as their other properties, can say that we can use fiber - reinforced composite as an acceptable method for reconstruction of endodotically treated maxillary pre molar