Fracture resistance of teeth restored with composite or ceramic inlays

Objectives: The objective of the present study was to evaluate fracture resistance of teeth restored with composite and bonded ceramic inlays. Methods: Twenty-six non-carious posterior human teeth were selected and stored in saline solution. Teeth were randomly divided in 3 groups: G1 control group (n=5) – no cavity preparation was performed; G2 unrestored teeth (n=5) – standard MOD inlay preparations was performed and teeth remained unrestored; G3 composite group (n=8) – MOD preparations were restored using dentin adhesive bonding (Single Bond –3M) and composite resin (P60 – 3M); and G4 bonded ceramic group (n=8) – MOD preparations were restored using dentin-bonding agent (Single Bond – 3M), resin cement (RelyX – 3M) and ceramic inlays (IPS D.SIGN - Ivoclar). The MOD inlay cavities were prepared with 1/3 of the intercuspal distance. A XL 3000 (3M) light curing unit was used during the experiment. Materials were used according to the manufacturer's instructions. After finishing and polishing, the specimens were subjected to the compressive load by a universal testing machine (Kratos), at crosshead speed of 0.5 cm/m. Results: Means were calculated in MPa, according to surface area of each tooth: G1=52.58 (± 22.32), G2=20.36 (± 4.09), G3=36.18 (± 10.14), and G4=26.86 (± 5.63). Data were submitted to statistical analysis using ANOVA and Tukey Post-Hoc test. G2 and G4 groups were similar and both showed lower fracture resistance than G1 (p<0.05). G3 exhibited intermediate values, being similar to G1 and G4. Conclusions: Based on the methodology employed it was concluded that cavity preparation reduced tooth resistance to fracture and ceramic restorations did not increase significantly this resistance.