Ralf Schön

Universitätsklinikum Freiburg, Freiburg an der Elbe, Lower Saxony, Germany

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Publications (102)116.57 Total impact

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    ABSTRACT: A prevalent modality to increase the amount of available bone prior to implantation is grafting of the maxillary sinus. Multiple factors such as the surgical technique, moment of implant placement as well as grafting materials and membranes are known to affect implant survival. However, the role of different factor combinations and associated reciprocal effects remain unclear. Conventional statistical methods do not consider inconsistency of study designs and do not take covariables into account. Hence, a systematic research and meta-analysis was conducted to investigate the influence of various treatment modalities on implant survival in the grafted maxillary sinus. A meta-analysis was conducted according to the PRISMA guidelines. Articles published from 1980 through January 2013 were electronically and manually searched in MEDLINE (Ovid), the Cochrane Register of Controlled Trials, the Database of Abstracts of Effects, and the Cochrane Database of Systematic Reviews. Clinical reports on single intervention sinus augmentation with root-form implants, a minimum of 10 patients and 6 months of loading were eligible for inclusion if implant survival was stated or calculable. Results were calculated by non-parametric univariate Kaplan-Meier analysis and Bayesian multivariate interval-censored Cox regression. A total of 122 publications on 16268 endosseous implants placed in grafted maxillary sinus were included. The treatment parameters surgical approach, grafting material and implant type showed no selective preference. However, application of membranes showed a significantly reduced hazard-ratio, independent of other co-factors. The use of membranes is the most significant factor to achieve long-term implant survival in sinus augmentation procedures. More data exceeding 3 years follow-up are needed to address prospective confounding and improve clinical evidence.
    PLoS ONE 09/2013; 8(9):e75357. · 3.53 Impact Factor
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    ABSTRACT: Fragestellung. Durch limitierte extraorale und transorale Inzisionen bei der endoskopisch assistierten operativen Versorgung von Kollumfrakturen wird das Risiko für eine N.-facialis-Schädigung und Narben im sichtbaren Bereich reduziert. Patienten und Methoden. Die endoskopisch assistierte operative Versorgung von Kollumfrakturen wurde bei 17 unselektierten Patienten, bei denen in dem Zeitraum von April 1998–Dezember 1999 die Indikation zur operativen Versorgung von Kollumfrakturen gestellt wurde, durchgeführt. 14 der 17 Patienten zeigten weitere Unterkieferfrakturen, 11 der operativ versorgten Kollumfrakturen waren disloziert, 7 nichtdisloziert. Bei 1 Patientin wurde eine bilaterale dislozierte Kollumfraktur operativ behandelt. Eine nichtdislozierte Kollumfraktur war nach offener Reposition und Osteosynthese einer Trümmerfraktur des aufsteigenden Unterkieferasts der Gegenseite auffällig und wurde konservativ behandelt. Zugänge. 9 der 17 Patienten wurden über einen submandibularen, 8 über einen transoralen Zugang operativ versorgt. Eine regelrechte Frakturreposition und Osteosynthese wurden über den submandibularen und den transoralen Zugang mit endoskopisch assistierter Technik erreicht. Bei 4 von den 8 Patienten, die über einen transoralen Zugang versorgt wurden, wurde unter Verwendung von gewinkelten Bohrern und Schraubendrehern die Osteosynthese transoral ohne transbukkale Stichinzision durchgeführt. Der transorale Zugang bewährte sich auch als zuverlässiger Zugang bei der operativen Versorgung von Kollumfrakturen mit Dislokation nach lateral. Der extraorale Zugang war bei stark dislozierten Kollumfrakturen mit Dislokation nach medial oder bei Trümmerfrakturen indiziert. Aim of the study. Using limited extraoral and transoral incisions for an endoscopically assisted open reduction of condylar mandible fractures, the risk of facial nerve damage and extensive visible scars can be reduced. Patients and methods. The endoscopically assisted treatment of 17 consecutive patients with fractures of the condyle was performed from April 1998 to December 1999. Of the 17 patients, 14 had additional mandibular fractures, and 11 of the condylar fractures were dislocated. Of the 17 patients, 9 were treated by submandibular and 8 by transoral approach. Adequate anatomic reduction was achieved by the submandibular and transoral approaches using an endoscopically assisted technique. Approaches. In four patients angulated drills and screwdrivers facilitated the transoral treatment of condylar fractures. Transbuccal stab incisions and the use of trocars were not needed in these four patients. The transoral approach proved to be a reliable surgical approach for fractures of the mandibular condyle even when dislocation with lateral override was present. The extraoral approach was used for severely dislocated fractures such as fractures with medial override or comminution. Kollumfraktur Endoskopisch assistierte Osteosynthese Extraoral TransoralFracture of the collum Endoscopically assisted osteosynthesis Extraoral Transoral
    Mund- Kiefer- und Gesichtschirurgie 07/2013; 6(4):236-240.
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    ABSTRACT: Gorham disease is a very rare condition associated with spontaneous destruction and resorption of 1 or more bones anywhere in the body. Many authors have suggested and/or implicated trauma as the initiating factor in the majority of the reported cases. It can affect almost all bones, and a combination of bones has been reported. In the maxillofacial skeleton, the first facial case was reported by Romer in 1928. Until now, only a few cases of Gorham disease affecting the maxillofacial bones, including this case report, have been reported. We present a brief review of the pathogenesis and treatment modalities of the disease and report a very rare clinical picture of the disease affecting a young and otherwise healthy patient with massive osteolysis of the mandibular bone and extensive involvement of the mouth floor and skin of the chin, which to our knowledge, is the only case report with skin manifestation affecting the maxillofacial region. Such skin manifestations play an important role for the diagnosis and add a clue for management of such condition.
    Oral surgery, oral medicine, oral pathology and oral radiology. 12/2012; 114(6):e23-9.
  • International Journal of Oral and Maxillofacial Surgery 10/2011; 40(10):1018-1018. · 1.36 Impact Factor
  • Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 06/2011; 69(6):1657-60. · 1.58 Impact Factor
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    ABSTRACT: Precise anatomical reconstruction of extensive orbital fractures is a challenging procedure for surgeons. Computer-assisted technologies, anatomical preformed implants and the possibility of acquiring 3D images using cone beam computed tomography are considered as the new standards. In this short review these applications are presented.
    Der Ophthalmologe 06/2011; 108(6):540-5. · 0.72 Impact Factor
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    ABSTRACT: Die präzise anatomische Rekonstruktion ausgedehnter Frakturen der Orbita stellt eine Herausforderung für den Chirurgen dar. Computerassistierte Techniken, anatomisch präformierte Implantate und die Möglichkeit der intraoperativen Bildgebung mittels digitaler Volumentomographie stellen einen neuen Standard in der primären und sekundären Orbitarekonstruktion dar. In diesem Übersichtsbeitrag sollen diese Verfahren dargestellt werden. Precise anatomical reconstruction of extensive orbital fractures is a challenging procedure for surgeons. Computer-assisted technologies, anatomical preformed implants and the possibility of acquiring 3D images using cone beam computed tomography are considered as the new standards. In this short review these applications are presented. SchlüsselwörterOrbitarekonstruktion–Anatomisch präformierte Implantate–Computerassistierte Chirurgie–Intraoperative Bildgebung–Orbitatrauma KeywordsOrbital reconstruction–Anatomical preformed implants–Computer-assisted surgery–Intraoperative imaging–Orbital trauma
    Der Ophthalmologe 01/2011; 108(6):540-545. · 0.72 Impact Factor
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    ABSTRACT: The aim of this study was to compare a combination of a locking system with self-tapping (ST-L) or self-drilling-tapping (SDT-L) screws with a combination of conventional miniplates with self-tapping (ST) and self-forming (SF) screws. A standardized osteotomy and osteosynthesis with one of the above mentioned systems was performed in 24 sheep. Callus formation was measured with the help of CT scans assisted by a navigation system. Specimens of each osteotomy gap were taken and examined histologically. The best results were observed when self-tapping screws and the Mini-Locking-System (ST-L) were applied. The slowest healing was seen in animals treated with miniplates and SF screws. After 8 weeks an increase in bone formation could be observed in the ST, SF, SDT-L systems. The results after 8 weeks were comparable with those achieved by the ST-L system after 4 weeks. The improved stability of the osteosynthesis with the ST-L system resulted in early ossification of the osteotomy gap and the smallest amount of callus formation.
    International Journal of Oral and Maxillofacial Surgery 11/2010; 40(1):94-102. · 1.52 Impact Factor
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    ABSTRACT: The use of a 2.0-mm locking plate system was evaluated in mandibular surgery. 53 patients (42 male, 11 female) with a total of 56 mandibular fractures were treated with a 2.0-mm mini-locking-plate system and retrospectively examined. Gender, age, cause of fracture, surgical access, classification of fractures, osteosynthesis, postsurgical findings and complications were evaluated. Assault in male patients (mean age 31) was the most common aetiological factor. Fractures in women (mean age 43 years) mostly occurred due to falls. Mandibular angle fractures were the most common and this anatomical site also presented the highest complication rate. Only 6% of patients had minor occlusal disturbance postoperatively, and minor complications (infections and dehiscence) occurred in 14% of patients in this study. Major complications only occurred in one patient included in the study (1.9%). Risk factors for the development of complications in this series were a history of alcohol or tobacco use, mandibular angle fractures, associated facial fractures, presurgical occlusal disturbance and concomitant dental infections. Surgical access to the fracture and the interval from injury to surgery was not associated with the development of complications. The use of a 2.0-mm locking plate system with its advantages of improved handling characteristics, increased stability, shorter surgical time and the preservation of bony perfusion is a viable alternative to conventional miniplates in the management of mandibular fractures.
    Journal of cranio-maxillo-facial surgery: official publication of the European Association for Cranio-Maxillo-Facial Surgery 02/2010; 38(7):501-4. · 1.25 Impact Factor
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    ABSTRACT: To evaluate current trends in maxillofacial trauma, a retrospective review of mandibular fractures at a German university hospital was carried out. In this retrospective study, records of 444 patients with mandibular fractures between 2000 and 2005 at the Department of Oral and Maxillofacial Surgery, University Hospital of Freiburg, Germany, were reviewed. A total of 444 patients presented with 696 mandibular fractures. Three hundred twenty-nine (74%) of the fractures occurred in male and 115 (26%) in female patients (2.9:1). One hundred forty-two fractures (32%) resulted from road traffic accidents, 126 from fights (28%), and 116 from falls (26%). Forty-four fractures were caused by sport accidents (10%) and 16 by pathologic fractures (4%). The mandibular condyle area was the most common fracture site, with 291 fractures (42%), followed by 144 fractures of the symphyseal and parasymphyseal area (21%) and 141 angle fractures (20%). Combined fractures were found in nearly half of the cases. Five hundred seventy-nine (83%) of patients with mandibular fractures were treated by surgical intervention, 117 (17%) of patients conservatively. Regarding the surgical treatment, 561 (65%) miniplates, 247 (29%) locking plates, and 51 (6%) lag screws were used. Complications, such as postoperative infections, abscesses, and osteomyelitis appeared in 66 (9%) cases. We concluded that osteosynthesis of mandibular fractures by miniplates and locking plates are both reliable.
    Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 07/2009; 67(6):1251-5. · 1.58 Impact Factor
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    ABSTRACT: This clinical case describes mandibular osteomyelitis in a healthy 31-year-old man as a severe complication following third molar removal. Recurrent abscess formations were treated with intensive therapy involving antibiotics, surgical debridement of the affected region, and hyperbaric oxygen. In the follow-up, despite microbiologic study to determine the indicated treatment approach, a severe osteomyelitis was present, clinically and radiographically. Finally, a partial resection of the mandible, including exarticulation, was indicated to manage this severe complication.
    Quintessence international (Berlin, Germany: 1985) 06/2009; 40(5):351-4. · 0.64 Impact Factor
  • Ralf Schön, Rainer Schmelzeisen
    Skull Base Surgery 04/2009; 19(01). · 0.60 Impact Factor
  • Skull Base Surgery 04/2009; 19(01). · 0.60 Impact Factor
  • Skull Base Surgery 04/2009; 19(01). · 0.60 Impact Factor
  • Skull Base Surgery 04/2009; 19(01). · 0.60 Impact Factor
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    ABSTRACT: Owing to the risk of facial nerve damage and the creation of visible scars, surgical treatment of condylar mandible fractures using an extraoral approach remains controversial. The transoral endoscopically assisted approach of condylar fractures has been reported to avoid these complications. A prospective, randomized controlled, multicenter trial was performed to quantify the patient benefit after open reduction and internal fixation of condylar mandible fractures using endoscopically assisted treatment compared with surgical treatment without endoscopic assistance. Patients with dislocated uni-/bilateral condylar neck fractures were randomized to receive either nonendoscopic open reduction and internal fixation using an extraoral (submandibular, preauricular, retromandibular) approach or a transoral endoscopic procedure. The primary functional outcome measure was investigated using the asymmetric Helkimo dysfunction score at 8 to 12 weeks and 1 year after surgery. A total of 74 patients were recruited between 2003 and 2006; the nonendoscopic extraoral group included 34 patients and the endoscopically assisted open reduction group included 40 patients. Comparable functional results were noted in both groups without any statistical significance. Endoscope-assisted treatment proved to be more time consuming. For the extraoral group, visible scars were rated by most of these patients as being cosmetically acceptable; however, a greater number of facial nerve injuries were reported. The treatment of condylar mandible fractures with a minimal invasive endoscopically assisted technique is reliable and may offer advantages for selected cases, particularly concerning the lower occurrence of facial nerve damage.
    Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 02/2009; 67(1):147-58. · 1.58 Impact Factor
  • R. Schön
    Der MKG-Chirurg 01/2009; 2(1):40-41.
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    ABSTRACT: To assess the prevalence of speech and swallowing impairment after radical surgery for oral and oropharyngeal cancer from the patient's viewpoint and to examine the association of these functional alterations with selected clinical characteristics regarding patients, tumors, and oncologic treatment. Cross-sectional, multicenter study using a self-administered questionnaire. Forty-three hospitals in Germany, Switzerland, and Austria. A total of 3894 questionnaires about rehabilitation problems after treatment for oral and oropharyngeal squamous cell carcinoma were sent to patients. Of these, 1652 were filled out and returned, and 1334 (80.8%) met the inclusion criteria. Morbidity associated with treatment of oral and oropharyngeal cancer. Speech problems were reported by 851 patients (63.8%), and swallowing problems were reported by 1006 patients (75.4%). The variables that presented a significant association with speech and swallowing impairment were sex, tumor location, pTNM stages, stage of tumor, treatment modality, and reconstruction type. This survey, based on patient perception, suggests that those who undergo radiotherapy associated with the surgical removal of a tumor, have late-stage tumors (III-IV), or have tumors located in the floor of the mouth should be informed of the greater risk of persistent severe speech and swallowing problems.
    Archives of otolaryngology--head & neck surgery 01/2009; 134(12):1299-304. · 1.92 Impact Factor
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    ABSTRACT: Today plate and screw osteosynthesis of mandibular fractures is a standard procedure in routine clinical practice. In this review, the breakthroughs and drawbacks of the development of this important aspect of maxillofacial surgery are followed-up. Medline search of relevant English and German literature. In 1886, Carl Hansmann was the first who applied steel screws and plates. Until today the material, the types of plates and applications have been continually improved. Over the last two decades miniplate osteosynthesis has induced a revolution in mandibular fracture treatment. The modern systems provide better handling, higher stability and less pressure on the bone. Modern miniplates have great advantages, like the intra-oral approach and the easy adaptability. In addition, it is no longer necessary to expose bone as extensively.
    Journal of Cranio-Maxillofacial Surgery 08/2008; 36(5):251-9. · 2.60 Impact Factor
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    ABSTRACT: Intraosseous malformations are rarely reported in the maxillofacial area. Because of bone growing processes, it is still a challenge to find the appropriate way to treat this disorder. The gold standard treatment for arteriovenous malformation is an endovascular embolization, combined with surgery. The case of a 14-year-old boy with arteriovenous malformation of the mandible was followed during a period of 8 years. Several embolizations and surgical interventions were required, culminating in bone reconstruction with a fibula graft to achieve normal mandibular form and function. There was no recurrence of the malformation during the follow-up period. To obtain stable results in the case of intraosseous arteriovenous malformations of the mandible, a combination of embolization and surgery is recommended. Superselective embolization is possible in an emergency case.
    Journal of Craniofacial Surgery 05/2008; 19(3):816-9. · 0.68 Impact Factor

Publication Stats

992 Citations
116.57 Total Impact Points


  • 2002–2012
    • Universitätsklinikum Freiburg
      • Oral and Maxillofacial Surgery Clinic
      Freiburg an der Elbe, Lower Saxony, Germany
  • 2011
    • St. Josefs Hospital
      Клоппенбург, Lower Saxony, Germany
  • 2002–2011
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany
  • 1999–2011
    • Deutsche Gesellschaft für Mund-, Kiefer- und Gesichtschirurgie e.V.
      Crefeld, North Rhine-Westphalia, Germany
  • 2009
    • Hannover Medical School
      Hanover, Lower Saxony, Germany
  • 2003
    • Center For Oral & Maxillofacial Surgery
      Georgia, United States