Inclusion Criteria:  Participants who had received a mandibular overdenture supported by two implants with either Locator attachments or a Dodler bar attachment following an immediate loading protocol as part of a randomized controlled trial [Kappel S, Giannakopoulos NN, Eberhard L, Rammelsberg P, Eiffler C. Immediate Loading of Dental Implants in Edentulous Mandibles by Use of Locator® Attachments or Dolder® Bars: Two-Year Results from a Prospective Randomized Clinical Study. Clin Implant Dent Relat Res. 2016 Aug;18(4):752-61. doi: 10.1111/cid.12349. Epub 2015 May 7. PMID: 25950679.] and for whom intact working casts with laboratory implant analogs representing the reference implant positions were available. Participant is legally capable Signed informed consent form available  Exclusion Criteria:  Participant not contactable Participant not willing to participate New overdenture or dolder bar attachment based on a working cast other than that used for immediate loading No intact working casts available Diagnosed epilepsy Pregnancy and lactation Local or systemic acute or chronic (also in the past) general medical diseases and conditions, which contradict a participation in the study and or expose the patient to a higher risk in case of a study participation Known allergies or intolerances to the materials used in the study. Lack of compliance