Displacement of a (part of a) radix or in some cases a part of a tooth into the floor of the mouth can occur during the extraction of a tooth in the mandibula. Possible causes of this are a lingual perforation of the radices or an inappropriate surgical technique. Leaving a fragment in situ in the floor of the mouth can lead to pain, swelling and trismus as a result of infection and/or spontaneous displacement of the fragment. We advise that the tooth or radix be removed as soon as possible. When experience is lacking in the removal of a tooth or radix from the floor of the mouth it is sensible to refer the patient to an oral surgeon. We also advise prescribing antibiotics in order to prevent infection.