Root filled premolar teeth restored with silorane and methacrylate-based resin composite

To compare fracture characteristics of root-filled teeth with variable cavity design restored with a low shrinkage silorane and methacrylate-based resin composite.

77 extracted maxillary premolars were divided randomly into seven groups; 1) intact teeth; Group 2, 3 and 4) MOD plus endodontic access with the buccopalatal width of the occlusal isthmus equals one third of the intercuspal width; Group 5, 6 and 7) MOD plus endodontic access with the buccopalatal width of the occlusal isthmus equals one half of the intercuspal width. Group 2 and 5 were left unrestored, group 3 and 6 were restored with a silorane-based resin composite (Filtek P90) and group 4 and 7 with a methacrylate- based resin composite (Z250). Teeth were loaded in a universal testing machine; load and fracture patterns were recorded and compared statistically using 2-way ANOVA and t-test for pairwise comparisons and 1-way ANOVA with Dunnett test for multiple comparisons.

Unrestored teeth became progressively weaker with more extensive preparations, group 5 (Unfilled ½) showed the lowest fracture load among the groups (71 ± 22 N, P < 0.001). Restorations increased the fracture strength of unrestored teeth regardless of cavity size (P < 0.001), but was still significantly weaker than sound teeth, with no significant difference between silorane and methacrylate groups. Failure of restored teeth was mostly adhesive at the tooth restoration interface.

Silorane-based resin composite have no superior strengthening effect over the conventional methacrylate-based resin composite in restoration of root filled teeth. Both materials showed similar fracture patterns.

Clinical significance: Root filled teeth are considerably weakened via restorative and endodontic procedures. A direct adhesive restoration will aid in preserving tooth structure as far as it provides enough strength.