Chemistry and Materials science

Future generations of dental Zirconia should combine high fracture toughness and strength, the key factors for durable dental restorations. Resisting clinical fractures is one of the key features that will prove more use and safe use of Zirconia for dental application and biomedical implants.​

Zirconia substituted with Y2O3, CeO2 and CaO exhibits high fracture toughness and ability arrests crack propagation​

• A ceramic material, but as tough as a “ceramic steel”​

Tetragonal zirconia (t) transforms to monoclinic (m) structure at the crack tip → 4.3% volume expansion closes the crack​

• t-phase → high strength and fracture toughness​
• t′, t″, and c (cubic) phases cannot transform to m​

Requires further development for expanded applications​

• Understanding the stability of the t-phase versus its transformability to m​
• Grain size in nano-range for increased grain size toughening​
• Sinterability, densification and optical properties​
• Evaluation using clinically relevant testing – realistic designs and clinically relevant fractures

NIOM employs organic analytical chemistry to identify, quantify, and structurally characterize small organic molecules released by dental biomaterials, and to elucidate their reactions and biological fate using in vitro bioassays.

Analytical methods and targets

We develop and validate targeted chromatography–mass spectrometry (LC‑MS/MS and GC‑MS) methods to quantify key components in leachates from dental materials, including methacrylate monomers (HEMA, TEGDMA, UDMA, BisGMA, BisEMA homologues, etc.), photoinitiators, stabilizers, and bisphenol A. We have extensive experience using an artificial saliva model containing salts, small organic molecules, mucin, and α‑amylase as a chemically defined surrogate to study leaching from, for example, printed dental biomaterials, thereby directly linking chromatography‑MS‑based quantification to oral exposure modelling.
In addition to targeted analyses, NIOM also utilizes untargeted high‑resolution mass spectrometry to achieve broad chemical coverage. Datasets from untargeted analyses require further evaluation using statistical modelling and bioinformatics and often reveal a larger number of putative leachables, indicating more complex release patterns than those suggested by targeted analysis alone.

Reaction and biotransformation studies

To understand and investigate how biomaterial components, such as methacrylates, interact with biomolecules, NIOM combines LC‑MS techniques with NMR spectroscopy (in collaboration with the University of Oslo). For example, we have studied the reactions of dental methacrylates with thiols such as L‑cysteine and glutathione. The synthesis and structural characterization of HEMA–thiol conjugates, and their subsequent use as reference standards, enabled us to demonstrate their formation in an osteoblast‑like cell line exposed to HEMA, thereby directly linking dental monomer chemistry to cellular detoxification pathways.

Metabolomics

In a broader oral health context, untargeted LC‑HRMS‑based metabolomics can generate new knowledge on interactions of either biomaterial components or other xenobiotic substances with biological systems. For instance, we have used nicotine‑exposed monocytes to map biotransformation products and nicotine‑induced metabolic perturbations, illustrating how organic analytical chemistry can reveal pathway‑level effects of oral exposures such as snuff or nicotine pouches.