Comparative Evaluation of Flexural Strength of Heat Polymerised Polymethyl Methacrylate Provisional Fixed Restorative Resin Reinforced with Different Percentages of Silanised Zirconium Oxide Nanoparticles: An In-vitro Study

Introduction: The purpose of providing a provisional restoration includes immediate replacement of missing teeth, for protection of pulp and maintenance of periodontal health, to maintain occlusal stability, to preserve the position of the teeth and for masticatory efficiency. Provisional restorations fabricated from heat processed acrylic resin have been used successfully. Incorporation of inorganic nanoparticles into Polymethyl Methacrylates (PMMA) resin has been shown to improve its physical properties.

Aim: To evaluate and compare the flexural strength of heat polymerised PMMA provisional restorative resin reinforced with different percentages of silanised zirconium oxide nanoparticles.

Materials and Methods: This is an in-vitro study performed in the Department of Prosthodontics, VSPM’s Dental College and Research Centre, Nagpur, Maharashtra, India, from June 2018 to February 2020. A die was used to create sixty heat-cured PMMA resin specimens, which were then divided into four groups: group A includes controls with conventional heat polymerised provisional restorative resin (PMMA) and groups B, C and D conventional heat polymerised provisional restorative resin reinforced with different percentages of silanised zirconium oxide nanoparticles (1 wt%, 2.5 wt%, 5 wt%, respectively), having fifteen specimens in each group. Three point bending tests were conducted on all samples using a universal testing machine. The flexural strength of each specimen was calculated. Mean value of flexural strength of each group was used for statistical analysis. One-way analysis of variance test was used to find out the mean value of flexural strength of each group.

Results: The mean flexural strength for control group was 53.76±2.97 MPa. For group B (1% Zirconium oxide) it was 58.14±4.86 MPa, for group C (2.5% Zirconium oxide) was 63.29±4.22 and for group D (5% Zirconium oxide) it was 59.02±3.99 MPa. Statistical analysis showed that maximum strength was obtained by reinforcement with 2.5% silanised zirconium oxide nanoparticles.

Conclusion: Polymethyl methacrylate reinforced with silanised 2.5% of zirconium oxide nanoparticles promises to be better material in terms of flexural strength.