Ethical aspects
The study was carried out in accordance with approved guidelines and regulations of the local Ethics Committee (Kantonale Ethickkomission, KEK), where pooled samples of teeth and saliva are categorized as “irreversibly anonymized” and therefore exempt of ethical approval. The volunteers were previously informed about the use of their teeth and/or their saliva in research and their informed consent was obtained. Since the teeth and saliva used in the present study were pooled, according to KEK previous ethical approval is not required.