[1] Univ Dusseldorf, Dept Operat Dent Periodontol & Endodontol, Moorenstr 5,Bldg 18-13, D-40225 Dusseldorf, Germany
[2] Univ Dusseldorf, Univ Childrens Hosp, Dept Gen Paediat, Moorenstr 5,Bldg 14, D-40225 Dusseldorf, Germany
[3] Univ Witten Herdecke, Dept Operat & Prevent Dent, Witten, Germany
[4] Univ Dusseldorf, Inst Med Microbiol & Hosp Hyg, Moorenstr 5,Bldg 22-21, D-40225 Dusseldorf, Germany