WR is a senior physician at the University Hospital Halle, Martin Luther University Halle-Wittenberg, Department of Oral and Plastic Maxillofacial Surgery, Halle/Saale, Germany.

RS is a clinical research associate at the University School of Dental Medicine, Department of Prosthetic Dentistry, Martin Luther University Halle-Wittenberg, Halle/Saale, Germany.

CH is a consultant at the University Hospital Halle, Martin Luther University Halle-Wittenberg, Department of Oral and Plastic Maxillofacial Surgery, Halle/Saale, Germany.

JH is an assistant professor at the University School of Dental Medicine, Department of Prosthetic Dentistry, Martin Luther University Halle-Wittenberg, Halle/Saale, Germany.

BA is professor and the head of the department at the University Hospital Halle, Martin Luther University Halle-Wittenberg, Department of Oral and Plastic Maxillofacial Surgery, Halle/Saale, Germany.

AWE is a senior assistant professor at the University Hospital Halle, Martin Luther University Halle-Wittenberg, Department of Oral and Plastic Maxillofacial Surgery, Halle/Saale, Germany.

All procedures performed in the study were in accordance with the ethical standards of the institutional research committee (date of issue 21 August 2014, registration number 2014-60) and with the 1964 Helsinki declaration and its later amendments.

Informed consent was obtained from all individual participants included in this study.

Not applicable

Waldemar Reich, Ramona Schweyen, Christian Heinzelmann, Jeremias Hey and Alexander Walter Eckert declare no competing interest.

Bilal Al-Nawas is giving lectures for Straumann, Camlog, Dentsply, Nobel biocare, Geistlich.

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