IADR Abstract Archives
Detecting Subsurface Defect in Bulkfill Composite Resins Restorations After Curing
Objectives: Placing bulk-fill composite resins (BFCR) greater than 2 mm has raised concerns regarding the adaptation of the material causing debond from internal walls. This study aimed to identify subsurface debond immediately after curing by the dynamic of BFCR polymerization shrinkage
Methods: An in-vitro studies, Class-I cavities of 4 x 4 x 4 mm3 were prepared in 25 extracted molars and divided into 5 groups (n:5): G1 - bonded at all surfaces, G2 – debonded at floor, G3 – debonded at mesial wall, G4 - debonded at two adjacent walls and G5 – debonded at two opposing walls. Finite element analysis of the Class-I restoration was carried out using Abaqus 6.13 with dimensions of the model 10.5 mm x 12.4 mm x 7.8 mm for the tooth, 4 x 4 x 4 mm3 for the composite resins and 10-mm thick for the adhesive layer. Linear displacement (LD) were measured from the experiment utilizing microCT and FEA simulation. Agreement between the microCT-measurement and FE-predicted methods were analysed.
Results: The micro-CT images and FEA showed that displacements did occur at all free and debond surfaces, with the largest displacement at the middle of occlusal surface restoration. MicroCT measured LD were G1:62.4±5.2µ, G2:32.8±4.0µ, G3:34.5±4.1µ, G4:30.8±4.8µ and G5:29.4±6.1µ. The FEA values were G1:46.8µ, G2:34.6µ, G3:37.7µ, G4:32.3µ and G5:30.5µ. G1 exhibited the highest value and G5 the lowest in both measurement methods. One-way ANOVA showed significant difference (p<0.05) between G1 to G2, G3, G4 and G5, but no significant difference (p>0.05) noted between G2, G3, G4 and G5.
Conclusions: Debond walls or floor in restorations gave a specific characteristic on the LD polymerization shrinkage. The in-vitro experiment and FEA confirmed that subsurface debond significantly reduces the linear surface displacement of composite resins restoration from a fully bonded restoration.
Methods: An in-vitro studies, Class-I cavities of 4 x 4 x 4 mm3 were prepared in 25 extracted molars and divided into 5 groups (n:5): G1 - bonded at all surfaces, G2 – debonded at floor, G3 – debonded at mesial wall, G4 - debonded at two adjacent walls and G5 – debonded at two opposing walls. Finite element analysis of the Class-I restoration was carried out using Abaqus 6.13 with dimensions of the model 10.5 mm x 12.4 mm x 7.8 mm for the tooth, 4 x 4 x 4 mm3 for the composite resins and 10-mm thick for the adhesive layer. Linear displacement (LD) were measured from the experiment utilizing microCT and FEA simulation. Agreement between the microCT-measurement and FE-predicted methods were analysed.
Results: The micro-CT images and FEA showed that displacements did occur at all free and debond surfaces, with the largest displacement at the middle of occlusal surface restoration. MicroCT measured LD were G1:62.4±5.2µ, G2:32.8±4.0µ, G3:34.5±4.1µ, G4:30.8±4.8µ and G5:29.4±6.1µ. The FEA values were G1:46.8µ, G2:34.6µ, G3:37.7µ, G4:32.3µ and G5:30.5µ. G1 exhibited the highest value and G5 the lowest in both measurement methods. One-way ANOVA showed significant difference (p<0.05) between G1 to G2, G3, G4 and G5, but no significant difference (p>0.05) noted between G2, G3, G4 and G5.
Conclusions: Debond walls or floor in restorations gave a specific characteristic on the LD polymerization shrinkage. The in-vitro experiment and FEA confirmed that subsurface debond significantly reduces the linear surface displacement of composite resins restoration from a fully bonded restoration.