In dentistry, cobalt-based alloys are widely used by dental technicians in performing fixed dental prosthetic work. For economic reasons, dental technicians often reuse the surplus that remains after casting the metal being a rather controversial practice in terms of guaranteeing future prosthetic restorations that they will perform. The main objective of this study is to identify local clinical adverse reactions of oral tissues on contact with dental alloys on Cobalt berry when reusing this previously molten alloy. The systematic review included several studies on the return of Co-based dental alloys over the past five years. The interaction between this dental alloy and the oral tissues can in some cases lead to allergies and various toxic effects due to the metal present. This review of the literature is important because the allergy rate has been shown to be higher than for other alloys used for the same purpose, therefore, it is recommended to replace this dental alloy whenever there is a suitable alternative. Patients who report such oral symptoms on contact with this dental alloy should have a thorough dental check-up to rule out oral pathology due to the use of such an alloy. These cases present a challenge both for the specialization of dentistry and for general medical specializations and a good collaboration between these medical professions can lead to the correct diagnosis and treatment of such oral pathologies.

Acknowledgements: “The work of the first author is supported by the project ANTREPRENORDOC, in the framework of Human Resources Development Operational Programme 2014-2020, financed from the European Social Fund under the contract number 36355/23.05.2019 HRD OP /380/6/13 – SMIS Code: 123847. The work of the second author was carried out in the framework of the research project DREAM (Dynamics of the REsources and technological Advance in harvesting Marine renewable energy), supported by the Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding – UEFISCDI, grant number PN-III-P4-ID- PCE-2020-0008.”