Medication Related Osteonecrosis of the Jaw (MRONJ) has traditionally been mostly attributed to the exposure to antiresorptive agents such as bisphosphonates and denosumab. Nevertheless, following the development of new medications in oncology, the spectrum of drugs associated with MRONJ widened, with, for example, tyrosine kinase inhibitors, mTOR inhibitor, or monoclonal antibodies against VEGF.

To date, MRONJ has not been assessed or reported in patients treated with guselkumab so far. Guselkumab is a fully human IgG1λ monoclonal antibody that selectively targets the p19 protein subunit of extracellular human IL-23 and inhibits its intracellular and downstream signalling. It consists of two identical light chains and two identical heavy chains. The four chains are linked together by covalent disulfide bonds and noncovalent protein-protein interactions.

The aim of this article is to report a case of a patient with severe psoriasic arhtritis and plaque psoriasis who presented with a clinical condition that could resemble a MRONJ following guselkumab therapy and a dental root extraction.