title: Analysis of reasons for osteonecrosis of the jaws.
abstract: OBJECTIVE
  Osteonecroses of the jaws are caused by several reasons. Bisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) is known since 2003 with an increasing incidence in the first years. Along with more knowledge about the pathophysiology, preventive strategies were implemented trying to reduce the incidence. The aim of this retrospective study was to analyze the frequency and overall proportion of BP-ONJ within the field of osteonecrosis. The data was compared to a similar study performed in 2005.
  
  
  METHODS
  All patients with osteonecrosis or osteomyelitis treated in the period from April 2005 to July 2012 in the Oral and Maxillofacial Surgery at the University of Mainz, Germany, were analyzed.
  
  
  RESULTS
  The reasons for osteonecrosis were bisphosphonates in 45 %, odontogenic or surgically induced osteonecrosis in 32 %, osteoradionecrosis in 17 %, traumas in 1 %, and in 4 % the reason remained unclear. The BP-ONJ became the most important factor for osteonecrosis. Its fraction in the years 2000-2005 was 10 % only.
  
  
  CONCLUSIONS
  Although preventive strategies are implemented, the number of new cases got bigger. The implemented prevention strategies did not manage to reduce the overall number of new cases. Furthermore, the launch of other medications with a similar side effect on the jawbone as the BP-ONJ for bisphosphonates might influence the overall distribution of osteonecroses.
authors.affiliation: Oral and Maxillofacial Surgery-Plastic Surgery, University Medical Center of the Johannes Gutenberg-University Mainz, Augustusplatz 2, 55131, Mainz, Germany, walter@mkg.klinik.uni-mainz.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Walter
authors.forename: Keyvan
authors.initials: K
authors.lastname: Sagheb
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bitzer
authors.forename: Roman
authors.initials: R
authors.lastname: Rahimi-Nedjat
authors.forename: Katherine Joyce
authors.initials: KJ
authors.lastname: Taylor
mesh_terms: D059266:Bisphosphonate-Associated Osteonecrosis of the Jaw / Q000453:epidemiology*; D050071:Bone Density Conservation Agents / Q000009:adverse effects; D004164:Diphosphonates / Q000009:adverse effects; D005151:Facial Injuries / Q000453:epidemiology; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D010025:Osteoradionecrosis / Q000453:epidemiology; D012189:Retrospective Studies
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates