1. Department of Conservative Dentistry and Periodontology; Center of Dental Traumatology; University of Würzburg; Würzburg Germany
2. Department of Periodontology, Endodontology and Cariology; Center of Dental Traumatology; University of Basel; Basel Switzerland
3. Department of Oral Surgery, Oral Radiology and Oral Medicine, Center of Dental Traumatology; University of Basel; Basel Switzerland