Modifying dental composites to formulate novel methacrylate-based bone cements with improved polymerisation kinetics, and mechanical properties

Muhammad Adnan Khan; António Hs Delgado; Anne M Young

doi:10.1016/j.dental.2023.10.010

Modifying dental composites to formulate novel methacrylate-based bone cements with improved polymerisation kinetics, and mechanical properties

Dent Mater. 2023 Dec;39(12):1067-1075. doi: 10.1016/j.dental.2023.10.010. Epub 2023 Oct 10.

Authors

Muhammad Adnan Khan¹, António Hs Delgado², Anne M Young³

Affiliations

¹ Dental Materials Department, Institute of Basic Medical Sciences, Khyber Medical University, Peshawar, Pakistan; Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, London, UK.
² Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, London, UK; Centro de Investigação Interdisciplinar Egas Moniz (CiiEM), Monte de Caparica, Almada, Portugal. Electronic address: asalesdelgado@egasmoniz.edu.pt.
³ Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, London, UK.

PMID: 37821331
DOI: 10.1016/j.dental.2023.10.010

Abstract

Objectives: The aim was to develop bone composites with similar working times, faster polymerisation and higher final conversion in comparison to Cortoss™. Additionally, low shrinkage/heat generation and improved short and longer-term mechanical properties are desirable.

Methods: Four urethane dimethacrylate based composites were prepared using tri-ethylene-glycol dimethacrylate (TEGDMA) or polypropylene dimethacrylate (PPGDMA) diluent and 0 or 20 wt% fibres in the glass filler particles. FTIR was used to determine reaction kinetics, final degrees of conversions, and polymerisation shrinkage/heat generation at 37 °C. Biaxial flexural strength, Young's modulus and compressive strength were evaluated after 1 or 30 days in water.

Results: Experimental materials all had similar inhibition times to Cortoss™ (140 s) but subsequent maximum polymerisation rate was more than doubled. Average experimental composite final conversion (76%) was higher than that of Cortoss™ (58%) but with less heat generation and shrinkage. Replacement of TEGDMA by PPGDMA gave higher polymerisation rates and conversions while reducing shrinkage. Early and aged flexural strengths of Cortoss™ were 93 and 45 MPa respectively. Corresponding compressive strengths were 164 and 99 MPa. Early and lagged experimental composite flexural strengths were 164-186 and 240-274 MPa whilst compressive strengths were 240-274 MPa and 226-261 MPa. Young's modulus for Cortoss™ was 3.3 and 2.2 GPa at 1 day and 1 month. Experimental material values were 3.4-4.8 and 3.0-4.1 GPa, respectively. PPGDMA and fibres marginally reduced strength but caused greater reduction in modulus. Fibres also made the composites quasi-ductile instead of brittle.

Significance: The improved setting and higher strengths of the experimental materials compared to Cortoss™, could reduce monomer leakage from the injection site and material fracture, respectively. Lowering modulus may reduce stress shielding whilst quasi-ductile properties may improve fracture tolerance. The modified dental composites could therefore be a promising approach for future bone cements.

Keywords: Biomaterials; Bone cement; Bone substitute; Dental composite; Mechanical properties; Polymerisation kinetics; Reaction kinetics.

MeSH terms

Bone Cements*
Composite Resins*
Dental Materials
Materials Testing
Methacrylates
Polyethylene Glycols
Polymethacrylic Acids
Stress, Mechanical

Substances

triethylene glycol dimethacrylate
Composite Resins
Bone Cements
ethylene dimethacrylate
Methacrylates
Polymethacrylic Acids
Polyethylene Glycols
Dental Materials