Physico-Mechanical Characteristics of Ormocer and Bulk Fill Composite Resin Restorative Materials: An in-vitro Study

Introduction: Bulk Fill (BF) resins and Ormocers are recently introduced composite restorative materials in order to overcome the disadvantage of polymerisation shrinkage exhibited by most of the conventional resin-based composites.

Aim: To evaluate the physical and mechanical properties of Organically Modified Ceramics (Ormocers) in comparison with BF composite resin restorative material.

Materials and Methods: In this in-vitro study, 20 human extracted premolars were allocated into two groups of 10 each. ORM (Group-1 Admira fusion, n=10) and BF (Group-2 Filtek BF, n=10) composite materials were used to prepare and restore Class-V cavities. The teeth were subjected to thermocycling and immersed in 1% methylene blue dye solution. Along the lateral walls of each sectioned specimen, depth of dye penetration was measured under the stereo microscope. A total of 20 rectangular (25x2x2 mm) and 20 disc (10x2 mm) shaped specimens of the above-mentioned materials were fabricated. Specimens of Flexural Strength (FS) were tested with the universal testing machine and Vickers hardness tester used for Surface Hardness (SH) evaluation. The data was statistically analysed using an unpaired t-test.

Results: Total of 20 extracted premolars were analysed. On inter-group comparison, it was observed that mean dye penetration was lowest for Group-1 (0.6±0.69) compared to Group-2 (2±0.81) and the difference observed was statistically significant (p=0.001). BF exhibited a lower FS of 211.69±43.9 compared to Ormocer 326.19±90.3, the difference is statistically significant (p=0.001). However, BF exhibited a higher SH of 38.3±0.15 compared to Ormocer 33.70±0.86, and the difference is statistically significant (p-value<0.001).

Conclusion: Ormocer exhibited improved marginal integrity and also higher FS compared to BF resin restorative materials. However, BF exhibited higher SH values compared to Ormocer.