COMPARATIVE EVALUATION OF MICROHARDNESS OF BULK FILL AND CONVENTIONAL COMPOSITE IN HIGH AND LOW VISCOSITY

Background: Composite resins are widely applied in dental restorations, yet conventional layering is slow and may
lead to shrinkage. Bulk-fill composites simplify placement with thicker increments, though their hardness and overall
mechanical reliability compared with traditional types are still uncertain.
Objective: This study aimed to assess and compare the surface microhardness of conventional and bulk-fill
composites with different viscosities to determine their relative suitability for stress-bearing restorations.
Methods: Sixty cylindrical specimens were prepared from four composite groups (n = 15 each): Estelite® Posterior
(high-viscosity conventional), Palfique® Universal Flow (low-viscosity conventional), Beautifil-Bulk Restorative
(high-viscosity bulk-fill), and Beautifil-Bulk Flowable (low-viscosity bulk-fill). Specimens were polymerized
following manufacturer instructions and tested using a Vickers microhardness tester under a 200 g load for 15 seconds.
Mean values were analyzed using one-way ANOVA with Tukey’s post hoc test (p < 0.05).
Results: Estelite® Posterior exhibited the highest microhardness (78.92 ± 7.74 MPa), significantly greater than
Palfique® Universal Flow (53.18 ± 6.55 MPa), Beautifil-Bulk (53.18 ± 10.73 MPa), and Beautifil-Bulk Flowable
(50.86 ± 4.72 MPa) (p≤0.001). No statistically significant differences were observed among the flowable and bulk-fill
groups (p>0.05).
Conclusion: Conventional composites demonstrated superior microhardness compared with both bulk-fill and
flowable systems, underscoring their continued relevance in high-stress clinical applications. Nevertheless, recent
improvements in bulk-fill formulations have reduced performance gaps, suggesting their potential as efficient
alternatives in cases where reduced chair time and simplified placement are prioritized. Further studies evaluating
additional mechanical and biological properties are warranted to establish their long-term clinical reliability.