@entity174 resistance of endodontically treated maxillary premolars restored by XXXX -based composite with or without fiber or nano-ionomer.

@entity691 @entity11379 @entity16971 @entity174
PURPOSE: This in vitro study investigated the @entity174 resistance of endodontically treated premolars restored using @entity16971 - or @entity11379 -based composite along with or without fiber or nano-ionomer base. MATERIALS AND METHODS: Ninety-six intact maxillary premolars were randomly divided into eight groups (n = 12). G1 (negative control) was the intact teeth. In Groups 2-8, root canal treatment with mesio-occlusodistal preparation was performed. G2 (positive control) was kept unrestored. The other groups were restored using composite resin as follows: G3, @entity11379 -based composite (Z250); G4, @entity11379 composite (Z250) with @entity691 fiber; G5 and G6, @entity16971 -based composite (Filtek P90) without and with the fiber, respectively; G7 and G8, @entity11379 - and @entity16971 -based composite with nano-ionomer base, respectively. After aging period and thermocycling for 1000 cycles, @entity174 strength was tested and @entity174 patterns were inspected. The results were analyzed using ANOVA and Tukey HSD tests (a=0.05). RESULTS: Mean @entity174 resistance for the eight groups (in Newton) were G1: 1200    169(a), G2: 360    93(b), G3: 632    196(c), G4: 692    195(c), G5: 917    159(d), G6: 1013    125(ad), G7: 959    148(d), G8: 947    105(d) (different superscript letters revealed significant difference among groups). Most of the @entity174 in all the groups were restorable, except Group 3. CONCLUSION: @entity16971 -based composite revealed significantly higher strength of the restored premolars compared to that of @entity11379 one. Fiber insertion demonstrated no additional effect on the strength of both composite restorations; however, it increased the prevalence of restorable @entity174 of @entity11379 -based composite restored teeth. Using nano-ionomer base under @entity11379 -based composite had a positive effect on @entity174 resistance and pattern. Only fiber-reinforced @entity16971 composite restoration resulted in a strength similar to that of the intact teeth.
