Prof. Dr. Ralf Bürgers

Prof. Dr. Ralf Bürgers

Prof. Dr. Ralf Bürgers

Klinikdirektor Prothetik
Seit 07/2013 in der Abteilung
Telefon

0551-39-65654

Fax
0551-39-22800
Ort
UBFT, 4.C1.209

Spezialist für Zahnärztliche Prothetik (DGPro)
Fortgebildeter Gutachter (DGPro)
Tätigkeitsschwerpunkt für Parodontologie (DGParo)

 

  • Implantatprothetik
  • Abnehmbarer und festsitzender Zahnersatz
  • Diagnostik und Therapie von Kiefergelenkserkrankungen
  • Klinkdirektor, Lehrstuhlinhaber
  • Sprecher der Kommission für außerplanmäßigen Professor*innen der UMG
  • Mitglied Ausschuss für Zahnärztliche Lehre
  • Prüfer für Zahnersatzkunde in der Zahnärztlichen Prüfung (Staatsexamen) und Zahnärztlichen Vorprüfung (Physikum)
  • Gerichtsgutachten
  • 1976                Geboren in München
  • 1997 – 2003   Studium der Zahnmedizin an der Universität Regensburg
  • 2003 – 2005 Assistent in der Poliklinik für Zahnerhaltung und Parodontologie der Universität Regensburg (Prof. Dr. G. Schmalz)
  • 2005 Promotion „Helicobacter pylori in Mundhöhle und Magen“ bei Prof. Dr. S. Ruhl (University at Buffalo, USA)
  • 2005 – 2008 Assistent in der Poliklinik für Zahnärztliche Prothetik der Universität Regensburg (Prof. Dr. G. Handel)
  • 2009 Habilitation („Mikrobielle Adhäsion auf dentalen Biomaterialien“) und Venia Legendi Ernennung zum Oberarzt
  • 2012 Ruf der Georg-August-Universität Göttingen auf den Lehrstuhl für Zahnärztliche Prothetik
  • seit 2013 Klinikdirektor und Lehrstuhlinhaber Zahnärztliche Prothetik
  • 2007 Wrigley Prophylaxe Preis der Dt. Gesellschaft für Zahnerhaltung
  • 2009 Alex-Motsch-Preis der Deutschen Gesellschaft für Funktionsdiagnostik und –therapie
  • 2015 ITI Fellow
  • Dt. Gesellschaft für Zahn-, Mund- und Kieferheilkunde (DGZMK)
  • Dt. Gesellschaft für Prothetische Zahnmedizin und Biomaterialien (DGPro)
  • Dt. Gesellschaft für Funktionsdiagnostik und –therapie (DGFDT)
  • Dt. Gesellschaft für Parodontologie (DGParo)
  • Int. Association for Dental Research (IADR)
  • Antimikrobielle Oberflächen
  • Orale Biofilme
  • Craniomandibuläre Dysfunktionen

1. R. Bürgers, M. Rosentritt, G. Handel

„Bacterial adhesion of Streptococcus mutans to temporary crown and bridge material”

J Prosthet Dent (2007); 98(6): 461-469 [Imp. 1,009]

2. A. Faltermeier, R. Bürgers, M. Rosentritt

“Bacterial adhesion of Streptococcus mutans to orthodontic adhesives with various filler-volume fractions”

Am J Orthod Dentofacial Orthop (2007); 132(6): 728.e7-728.e11 [Imp. 1,126]

3. R. Bürgers, J. Wagner, G. Handel

„Schmelzmatrixproteine bei der plastischen Deckung singulärer und multipler Rezessionen“

ZWR – Das deutsche Zahnärzteblatt (2007); 116(7+8): 353-358

4. R. Bürgers, G. Schmalz, G. Handel 

„Behandlung einer generalisierten aggressiven Parodontitis unter Berücksichtigung regenerativer Therapien“

Quintessenz Zahnmedizin (2007); 58(8): 755-766

5. M. Rosentritt, S. Hahnel, G. Gröger, B. Mühlfriedel, R. Bürgers, G. Handel
„Adhesion of Streptococcus mutans to various dental materials in a laminar flow chamber system”

J Biomed Mater Res B Appl Biomater (2008); 86(1): 36-44 [Imp. 2,030]

6. S. Hahnel, M. Rosentritt, R. Bürgers, G. Handel

„Surface properties and in vitro Streptococcus mutans adhesion to dental resin polymers”
J Mater Sci Mater Med (2008); 19(7): 2619-2627 [Imp. 1,508]

7. A. Faltermeier, R. Bürgers, M. Rosentritt

„Bacterial adhesion of Streptococcus mutans to esthetic bracket materials”

Am J Orthod Dentofacial Orthop (2008); 133(4 Suppl): 99-103 [Imp. 1,442]

8. R. Bürgers, M. Rosentritt, W. Schneider-Brachert, M. Behr, G. Handel, S. Hahnel

„Efficacy of denture disinfection methods for controlling Candida albicans colonization in vitro”

Acta Odontol Scand (2008); 66:174-180 [Imp. 1,095]

9. R. Bürgers, W. Schneider-Brachert, U. Reischl, A. Behr, K.-A. Hiller, N. Lehn, G. Schmalz, 

S. Ruhl

Helicobacter pylori in human oral cavity and stomach”

Eur J Oral Sci (2008); 116: 297-304 [Imp. 1,957]

10. S. Hahnel, R. Bürgers, G. Handel

„Xerostomie – ein Überblick über Ätiologie, Klinik, Diagnostik und Therapie”

ZWR – Das deutsche Zahnärzteblatt (2008); 117: 349-356

11. S. Hahnel, M. Rosentritt, R. Bürgers, G. Handel

„Adhesion of Streptococcus mutans NCTC 10449 to artificial teeth: An in vitro study”

J Prosthet Dent (2008); 100(4): 309-315 [Imp. 1,139]

12. S. Hahnel, M. Rosentritt, G. Handel, R. Bürgers

„Influence of saliva substitute films on initial Streptococcus mutans adhesion to enamel and dental substrata“

J Dent (2008); 36(12): 977-983 [Imp. 2,033]

13. R. Bürgers, G. Schmalz, G. Handel

„Tratamentul unei parodontite generalizate agresive cu utilizarea formelor de terapie regenerative”

Quintess Int Roman (2008); 6: 507-519

14. S. Hahnel, A. Leyer, M. Rosentritt, G. Handel, R. Bürgers

„Surface properties and in vitro Streptococcus mutans adhesion to self-etch adhesives“

J Adhes Dent (2009); 11: 263-269 [Imp. 1,638]

15. R. Bürgers, M. Rosentritt, W. Schneider-Brachert, G. Handel, S. Hahnel
Candida albicans adhesion to composite resin materials”

Clin Oral Invest (2009); 13: 293-299 [Imp. 2,233] 

16. R. Bürgers, W. Schneider-Brachert, M. Rosentritt, , S. Hahnel, G. Handel

„Streptococcal adhesion to novel low-shrink silorane-based restorative”

Dent Mat; (2009); 25: 269-275 [Imp. 2,882]

17. S. Hahnel, M. Rosentritt, G. Handel, R. Bürgers

„In vitro evaluation of artificial ageing on surface properties and early Candida albicans adhesion to prosthetic resins“

J Mater Sci Mater Med (2009); 20(1): 249-255 [Imp. 1,955]

18. R. Bürgers, S. Hahnel, U. Reischl, R. Müller, M. Rosentritt, G. Handel, M. Behr

„Streptococcal adhesion to various luting systems and the role of mixing errors“

Acta Odontol Scand (2009); 67(3): 139-145 [Imp. 1,412]

19. R. Bürgers, T. Cariaga, R. Müller, U. Reischl, M. Rosentritt, G. Handel, S. Hahnel

„Effects of aging on surface properties and adhesion of Streptococcus mutans on various fissure sealants”

Clin Oral Invest (2009); 13(4): 419-426 [Imp. 2,233]

20. R. Bürgers, R. Frankenberger, A. Eidt, M. Rosentritt, H. Schweikl, G. Handel, S. Hahnel

„The anti-adherence activity and bactericidal effect of microparticulate silver additives in composite resin materials“

Arch Oral Biol (2009); 54(6): 595-601 [Imp. 1,649]

21. M. Behr, M. Rosentritt, J. Wimmer, R. Lang, R. Bürgers, G. Handel

„Self-adhesive resin cement versus zinc phosphate luting material: A prospective clinical trial begun 2003”

Dent Mater (2009); 25(5): 601-604 [Imp. 2,882]

22. M. Behr, R. Bürgers

“Tinnitus“

Dtsch Zahnärztl Z (2009); 64(3): 136-137 

23. S. Hahnel, M. Rosentritt, G. Handel, R. Bürgers

„Surface characterization of dental ceramics and initial streptococcal adhesion in vitro”

Dent Mater (2009); 25: 969-975 [Imp. 2,882] 

24. M. Rosentritt, M. Behr, R. Bürgers, A. Feilzer, S. Hahnel

„In vitro adherence of oral streptococci to zirconia core and veneering glass-ceramics”

J Biomed Mater Res B: Appl Biomater (2009); 91: 257-263 [Imp. 2,185] 

25. S. Hahnel, M. Behr, G. Handel, R. Bürgers

„Saliva substitutes for the treatment of radiation-induced xerostomia – a review”

Support Care Cancer (2009); 17: 1331-1343 [Imp. 2,089] 

26. M. Gosau, F. Draenert, S. Müller, B. Frerich, R. Bürgers, T. Reichert, O. Driemel

„Two modifications in the treatment of keratocystic odontogenic tumors (KCOT) and the use of Carnoy’s solution (CS) – a retrospective study lasting between 2 and 10 years”

Clin Oral Invest (2010); 14(1): 27-34 [Imp. 2,250]

27. L. Prantl, R. Bürgers, S. Schreml, J. Zellner, M. Gosau

„A novel antibacterial silicone implant material with short- and long-term release of copper ions”

Plast Reconstr Surg (2010); 125: 78e-80e [Imp. 2,647]

28. M. Gosau, S. Hahnel, F. Schwarz, T. Gerlach, T.E. Reichert, R. Bürgers

„Effect of six different peri-implantitis disinfection methods on in vivo human oral

biofilm”

Clin Oral Impl Res (2010); 26: 359-365 [Imp. 2,812]

29. R. Bürgers, S. Hahnel, T.E. Reichert, M. Rosentritt, M. Behr, T. Gerlach, G. Handel  

“Adhesion of Candida albicans to various dental implant surfaces and the influence of salivary pellicle proteins”

Acta Biomater (2010); 6: 2307-2313 [Imp. 4,824]

30. S. Hahnel, R. Bürgers, G. Handel, M. Rosentritt

„Investigation of mechanical properties of modern dental composites after artifical aging for one year“

Oper Dent (2010); 35: 414-421 [Imp. 1,560]

31. S. Hahnel, A. Henrich, M. Rosentritt, G. Handel, R. Bürgers

„Influence of artificial ageing on surface properties and Streptococcus mutans adhesion to dental composite materials“

J Mater Sci Mater Med (2010); 21: 823-833 [Imp. 2,325] 

32. R. Bürgers, T. Gerlach, S. Hahnel, F. Schwarz, G. Handel, M. Gosau

„In vivo and in vitro biofilm formation on two different titanium implant surfaces”

Clin Oral Impl Res (2010); 21: 156-164 [Imp. 2,812]

33. M. Gosau, L. Prantl, A. Eidt, M. Feldmann, A. Kokott, S. Hahnel, R. Bürgers

“The effects of copper additives on the quantity and cell viability of adherent Staphylococcus epidermidis in silicone implant material”

Biofouling (2010); 26: 359-365 [Imp. 3,333]

34. S. Hahnel, M. Behr, M. Rosentritt, V. Kopzon, R. Bürgers, G. Handel

“The effects of erroneous mixing of zinc carboxylate cements”

J Oral Sci (2010); 52(1): 89-93

35. S. Hahnel, T. Ettl, M. Rosentritt, G. Handel, R. Bürgers

„Influence of saliva substitute films on the initial adhesion of Candida albicans to dental substrata prior to and after artificial aging”

Arch Oral Biol (2010); 55:391-396 [Imp. 1,463]

36. R. Bürgers, S. Hahnel, M. Rosentritt, G. Handel

„Biofilmbildung auf dentalen Implantatoberflächen”

ZWR – Das deutsche Zahnärzteblatt (2010); 119: 244-252

37. W. Waiss, R. Bürgers, W. Kleeberger, T.E. Reichert

„Differentialdiagnose der Wangenschwellung: Lymphangiom“

Zahnärztl Mitteilungen (2010); 23: 50-54

38. R. Bürgers, T. Gerlach

„Regenerative Parodontalchirurgie“

ZMK (2011); 26: 762-768

39. S. Müller, R. Bürgers, M. Ehrenfeld, M. Gosau

“Macroplate fixation of fractures of the edentulous atrophic mandible: immediate function and masticatory rehabilitation”

Clin Oral Invest (2011); 15: 151-156 [Imp. 2,364]

40. V. Vielsmeier, T. Kleinjung, J. Strutz, R. Bürgers, P. M. Kreuzer ., B. Langguth 

„Tinnitus with temporomandibular joint disorders – a specific entity of tinnitus patients?”

Otolaryng Head Neck Surg (2011); 145(5): 748-752 [Imp. 1,630]

41. M. Behr, S. Meier, S. Hahnel, R. Bürgers, G. Handel, M. Rosentritt

„Glass ionomer layer thickness and its influence on zirconia failure“

J Mech Behav Biomed Mater (2011), 4(7): 1567-1570 [Imp. 2,814]

42. S. Hahnel, M. Rosentritt, R. Bürgers, G. Handel, R. Lang

Candida albicans biofilm formation on soft denture liners and efficacy of cleaning
protocol“

Gerodontology (2012); 29(2): e383-3391 [Imp. 1,828]

43. S. Hahnel, G. Mühlbauer, , A. Ionescu, R. Bürgers, M. Rosentritt, G. Handel, I. Häberlein

Streptococcus mutans and Streptococcus sobrinus biofilm formation and metabolic activity on dental materials” 

Acta Odontol Scand (2012), 70(2): 114-121 [Imp. 1,358]

44. M. Behr, F. Zeman, T. Passauer, M. Koller, S. Hahnel, R. Bürgers, R. Lang, G. Handel, C. Kolbeck

“Clinical performance of cast clasp-retained removable partial dentures: A retrospective study”

Int J Prosthodont (2012); 25 (2):138-144 [Imp. 1,625]

45. M. Behr, S. Hahnel, A. Faltermeier, R. Bürgers, C. Kolbeck, G. Handel, P. Proff

“Two main theories on dental bruxism”

Ann Anat (2012), 194(2): 216-219 [Imp. 1,960]

46. S. Hahnel, R. Bürgers, M. Rosentritt, G. Handel, M. Behr

„Analysis of veneer failure of removable prosthodontics“

Gerodontology (2012), 29(2): e1125-e1128 [Imp. 1,828]

47. R. Bürgers, C. Witecy, S. Hahnel, M. Gosau

„The effect of various topical peri-implantitis antiseptics on Staphylococcus epidermidis, Candida albicans, and Streptococcus sanguinis

Arch Oral Biol (2012), 57(7): 940-947 [Imp. 1,549]

48. M. Gosau, R. Bürgers, T. Vollkommer, T. Holzmann, L. Prantl

“Effectiveness of antibacterial copper additives in silicone implants”

J Biomater Appl (2013), 28(2): 187-198 [Imp. 2,764]

49. C. Koch, R. Bürgers, S. Hahnel

Candida albicans adherence and proliferation on the surface of denture base materials”

Gerodontology (2013), 30(4): 309-313 [Imp. 0,806]

50. S. Viale-Bouroncle, R. Bürgers, C. Morsczeck, M. Gosau

„β-tricalcium phosphate induces apoptosis in dental follicle cells”

Calcif Tissue Int (2013), 92(5): 412-417 [Imp. 2,748]

51. R. Bürgers, T. Kleinjung, M. Behr, V. Vielsmeier 

„Is there a link between tinnitus and temporomandibular disorders?”

J Prosthet Dent (2014), 111(3): 222-227 [Imp. 1,753]

52. C. Winkler, L. Schäfer, O. Felthaus, J. Allerdings, S. Hahnel, M. Behr, R. Bürgers 

„The bacterial adhesion on and the cytotoxicity of various dental cements used for implant-supported fixed restorations”

Acta Odontol Scand (2014), 72(4): 241-250 [Imp. 1,030]

53. L. Raue, C.D. Hartmann, M. Rödiger, R. Bürgers, N. Gersdorff

“Anisotropic local physical properties of human dental enamel in comparison to properties of some common dental filling materials”

Acta Odontol Scand (2014); 72(8): 591-569 [Imp. 1,030]

54. B. Schminke, H. Muhammad, C. Bode, B. Sadowski, R. Gerter, N. Gersdorff, R. Bürgers, V. Rosen, N. Miosge

“A discoidin domain receptor 1 knock-out mouse as a novel model for osteoarthritis of the temporomandibular joint”

Cell Mol Life Sci (2014); 71(6): 1081-1096 [Imp. 5,808]

55. M. Rödiger, S. Rinke, F. Ehret-Kleinau, F. Pohlmeyer, K. Lange, R. Bürgers, N. Gersdorff

“Evaluation of removal forces of implant-supported zirconia copings depending on abutment geometry, luting agent and cleaning method during recementation”

J Adv Prosthodont (2014); 6(3): 233-240 [Imp. 0,640]

56. S. Rinke, R. Bürgers, D. Ziebolz, M. Rödiger

“Clinical outcome of double crown-retained implant overdentures with zirconia primary

crowns”

J Adv Prosthodont (2015); 7(4): 329-337 [Imp. 0,844]

57. S. Mueller, B. Hohlweg-Majert, R. Bürgers, T. Steiner, T.E. Reichert, K.D. Wolff, M. Gosau

“The functional and aesthetic reconstruction of midfacial and orbital defects ba combining free flap transfer and craniofacial prosthesis”

Clin Oral Invest (2015), 19(2): 413-419 [Imp. 2,207]

58. S. Rinke, H. Rasing, N. Gersdorff, R. Bürgers, M. Rödiger

“Implant-supported overdentures with different bar designs: a retrospective evaluation after

5-19 years of clinical function”

J Adv Prosthodont (2015), 7(4): 338-343 [Imp. 0,844]

59. D. Papavasileiou, M. Behr, T. Gerlach, R. Bürgers

“Peri-implant biofilm formation on luting agents used for cementing implant-supported fixed restoratives: a preliminary in vivo study”

Int J Prosthodont (2015), 28(4): 371-373 [Imp. 1,487]

60. B. Schminke, F. vom Orde, R. Gruber, H. Schliephake, R. Bürgers, N. Miosge

“The pathology of bone tissue during peri-implantitis”

J Dent Res (2015), 94(2): 354-361 [Imp. 4,602]

61. S. Krohn, N. Gersdorff, T. Wassmann, K.D. Merboldt, A.A. Joseph, R. Bürgers, J. Frahm

“Real-time MRI of the temporomandibular joint at 15 frames per second – A feasibility study”

Eur J Radiol (2016); 85(12): 2225-2230 [Imp. 2,462]

62. S. Rinke, K. Kramer, R. Bürgers, M. Rödiger

“A practice-based clinical evaluation of the survival and success of metal-ceramic and zirconia molar crowns: 5-year results”

J Oral Rehabil (2016); 43(2): 136-144 [Imp. 2,098]

63. M. Gosau, M. Haupt, S. Thude, M. Strowitzki, B. Schminke, R. Bürgers

“Antimicrobial effects and biocompatibility of novel metallic nanocrystalline implant coatings”

J Biomed Mater Res B Appl Biomater (2016) 104(8): 1571-1579 [Imp. 3,189]

64. T. Ettl, J. Weindler, S. Müller, M. Hautmann, F. Zeman, M. Koller, D. Papavasileiou,  R.

Bürgers, O. Driemel, I. Schneider, C. Klingelhöffer, J. Meier, U. Wahlmann, T.E. Reichert

“Impact of radiotherapy on implant-based prosthetic rehabilitation in patients with head and neck cancer: A prospective observational study on implant survival and quality of life-Preliminary results”

J Craniomaxillofac Surg (2016), 44(9): 1453-1462 [Imp. 1,583]

65. T. Wassmann, S. Kreis, M. Behr,  R. Bürgers

“The influence of surface texture and wettability on initial bacterial adhesion on titanium
and zirconium oxide dental implants”

Int J Implant Dent (2017), 3(1): 32.doi

66. M. Rödiger, A. Heinitz, S. Rinke, R. Bürgers

“Fitting accuracy of zirconia single crowns produced via digital and conventional impressions – a clinical comparative study”

Clin Oral Investig (2017), 21(2): 579-587 [Imp. 2,386]

67. S. Krohn, P. Brockmeyer, D. Kubein-Meesenburg, C. Kirschneck, R. Bürgers

“Elongated styloid process in patients with temporomandibular disorders – is there a link?”

Ann Anat (2018), 217: 118-124 [Imp. 2,241]

68. M. Rödiger, J. Kloß, N. Gersdorff, R. Bürgers, S. Rinke

“Removal forces of adhesively and self-adhesively luted implant-supported zirconia copings depend on abutment geometry”

J Mech Behav Biomed Mater (2018), 87: 119-123 [Imp. 3,485]

69. S. Rinke, J. Wehle, X. Schulz, R. Bürgers, M. Rödiger

“Prospective evaluation of posterior fixed zirconia dental prostheses: 10-year clinical results”

Int J Prosthodont (2018), 31(1): 35-42 [Imp. 1,490]

70. R. Bürgers, C. Morsczeck. O. Felthaus, M. Gosau, H.C. Beck, T.E. Reichert

“Induced surface proteins of Staphylococcus epidermidis adhering to titanium implant substrata”

Clin Oral Invest (2018), 22(7): 2663-2668 [Imp. 2,453]

71. S. Krohn, J. Frahm, K.D. Merboldt, T. Wassmann, A.A. Joseph, R. Bürgers

“Diagnosis of disk displacement using real-time-MRI”

J Prosthet Dent (2018), 119(2): 206-209 [Imp. 2,787]

72. S. Krohn, A.A. Joseph, D. Voit, T. Michaelis, K.D. Merboldt, R. Bürgers, J. Frahm

“Multi-slice real-time MRI of temporomandibular joint dynamics”

Dentomaxillofac Radiol (2019), 48(1): 20180162 [Imp. 1,796]

73. S. Rinke, L. Schneider, X. Schulz, V. Wiedemann, R. Bürgers, M. Rödiger

“Overdentures borne on less than four abutments with telescopic crowns: 5-year results of a retrospective clinical study”

Clin Oral Invest (2019), 23(8): 3153-3160 [Imp. 2,815]

74. A. Schubert, C. Ziegler, A. Bernhard R. Bürgers, N. Miosge

“Cytotoxic effects to mouse and human gingival fibroblasts of a nanohybrid ormocer versus dimethacrylate-based composites”

Clin Oral Invest (2019), 23(1): 133-139 [Imp. 2,815]

75. S. Krohn, T. Hampe, F. Brack, T. Wassmann, R. Bürgers

“Intraoral sensor-based monitoring of stabilization splint therapy in patients with myofascial pain”

Int J Comput Dent (2020), 23(1): 11-16 [Imp. 1,714 in 2019]

76. T. Wassmann, A. Schubert, F. Malinski, M. Rosentritt, S. Krohn, K. Techmer, R. Bürgers

“The antimicrobial and cytotoxic effects of a copper-loaded zinc oxide phosphate cement”

Clin Oral Invest (2020), 24(11): 3899-3909 [Imp. 2,812 in 2019]

77. S. Krohn, J. Frahm, A. Mahler, H. Dathe, S. Sedaghat, D. Kubein-Meesenburg, F. Linss, T. Wassmann, R. Bürgers

“Biomechanical analysis of temporomandibular joint dynamics based on real-time magnetic resonance imaging”

Int J Comput Dent (2020), 23(3): 235-244 [Imp. 1,714 in 2019]

78. S. Rinke, M. Rödiger, R. Bürgers

“Intraorale Scanner und digitale Abformung – Perspektiven für die zahnärztliche Praxis”

Quintessenz Zahntechnik (2020), 46(11): 1182-1196

79. A. Schubert , R. Bürgers , F. Baum , O. Kurbad , T. Wassmann

Influence of the Manufacturing Method on the Adhesion of Candida albicans and Streptococcus mutans to Oral Splint Resins

Polymers (Basel). 2021 May 11;13(10):1534. doi: 10.3390/poly,13101534

  • Hauptvorlesung Zahnersatzkunde I
  • Hauptvorlesung Zahnersatzkunde II
  • Vorlesungen TPK
  • Vorlesungen Phantomkurs I
  • Vorlesungen Phantomkurs II
  • Vorlesungen Werkstoffkunde I und II
  • Auscultando et practicando
  • Vorlesungen Orale Biologie