Signature pedagogies are widely used in professional education to prepare students for the complex and unpredictable nature of professional work. We argue that assessment moments involving professional artefacts contribute to the evaluation and formation of professional knowledge, skills and moral understandings -- and thus to the signature of the pedagogy. The 'authenticity' these professional artefacts add to assessment is of particular relevance for understanding the pedagogic signature. Drawing on interviews from a professional study programme in dental hygiene, we employ sociocultural theories to analyse how different assessment moments are used to evaluate and develop students' competences of working with professional artefacts: dental radiographs. The findings show how the use of professional artefacts in three different assessment moments requires students to engage deeply with the epistemic, practical and moral dimensions of their profession. Our study contributes both empirical and conceptual insights to the field's understanding of the inner workings of signature pedagogies.