title: An ultrastructural study on indirect trauma of dental pulp caused by maxillofacial impact injury in dogs.
abstract: BACKGROUND
  Indirect injuries of adjacent tissues and organs usually accompany maxillofacial impact injuries. However, studies on indirect dental pulp injury are rare. This study was designed to determine the characteristics of indirect dental pulp injury caused by impact injury of mandible in dogs.
  
  
  METHODS
  Eighteen dogs were divided equally into six groups with random allocation. Right mandible of each dog was impacted but teeth were not injured directly. Then, the animals were killed at appointed time points and ultrastructural changes in dental pulp of assigned teeth of each dog were investigated with transmission electron microscope.
  
  
  RESULTS
  Dental pulp of the fourth premolar of right mandible was injured very severely, but irreversible necrosis did not occur in the end. Dental pulp of the second premolar of right mandible was injured less severely and reversibly. Dental pulp of the second premolar of left mandible was injured mildly and temporarily.
  
  
  CONCLUSIONS
  In the indirect injury of dental pulp caused by maxillofacial impact injury, the injured area is relatively extensive. The effect of the trauma decreases progressively and sharply as the distance to the impact site increases. Ultrastructural changes in the damaged nerves take place early.
authors.affiliation: Department of Oral and Maxillofacial Surgery, College of Stomatology, Fourth Military Medical University, Xi'an, PR China. rcq180@sina.com
authors.forename: Changqun
authors.initials: C
authors.lastname: Ren
authors.forename: Ruifeng
authors.initials: R
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Tian
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: Shuxia
authors.initials: S
authors.lastname: Zhou
mesh_terms: D000818:Animals; D003782:Dental Pulp / Q000293:injuries* / Q000648:ultrastructure; D004195:Disease Models, Animal; D004285:Dogs / Q000293:injuries; D005151:Facial Injuries / Q000503:physiopathology*; D008334:Mandible / Q000648:ultrastructure*; D008337:Mandibular Fractures / Q000503:physiopathology; D008440:Maxillary Fractures / Q000503:physiopathology; D015599:Trauma Severity Indices