title: Establishment of a critical-sized alveolar defect in the rat: a model for human gingivoperiosteoplasty.
abstract: BACKGROUND
  Despite technical advancement, treatment of congenital alveolar clefts has remained controversial. Currently, primary alveolar cleft repair (i.e., gingivoperiosteoplasty) has a 41 to 73 percent success rate. However, the remaining patients have persistent alveolar bone defects requiring secondary grafting procedures. Morbidity of secondary procedures includes pain, graft resorption, extrusion or infection, and graft or tooth loss. The authors present a novel rat alveolar defect model designed to facilitate investigation of therapeutics aimed at improving bone formation following primary alveolar cleft repair in humans.
  
  
  METHODS
  Sixteen 8-week-old Sprague-Dawley rats underwent creation of a 7 x 4 x 3-mm complete alveolar defect from the maxillary incisors to the zygomatic arch. Four animals were humanely killed at each of the following time points: 0, 4, 8, and 12 weeks. Morphometric analysis of the alveolar defect was determined by means of micro-computed tomography and histology.
  
  
  RESULTS
  Micro-computed tomography demonstrated that new bone filled 43 +/- 5.6 percent of the alveolar defect at 4 weeks, 53 +/- 8.3 percent at 8 weeks, and 48 +/- 3.5 percent at 12 weeks. Histologically, at 4 weeks, proliferating fibroblasts and polymorphonuclear cells were scattered throughout the disorganized collagen in the intercalary gap. By 8 weeks, nascent woven bone spicules extended from the edges of the defect. At 12 weeks, the woven spicules had remodeled, with scant additional bone deposition.
  
  
  CONCLUSIONS
  This model creates a critical-size alveolar defect that is similar in size and location to human alveolar defects and is suitable for studying proposed therapeutics.
authors.affiliation: New York, N.Y. From the Institute of Reconstructive Plastic Surgery, New York University School of Medicine, and the Department of Biomaterials and Biomimetics, New York University College of Dentistry.
authors.forename: Phuong D
authors.initials: PD
authors.lastname: Nguyen
authors.forename: Clarence D
authors.initials: CD
authors.lastname: Lin
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Allori
authors.forename: John L
authors.initials: JL
authors.lastname: Ricci
authors.forename: Pierre B
authors.initials: PB
authors.lastname: Saadeh
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Warren