title: Bone regeneration with BMP-2 and hydroxyapatite in critical-size calvarial defects in rats.
abstract: BACKGROUND
  This study describes the effect of bone formation by BMP-2 (bone morphogenetic protein-2), a bone formation inducer, with or without hydroxyapatite (HAP) application to critical-size defects in rat calvarial bone.
  
  
  METHODS
  Twenty male Wistar rats were divided into four groups of 5 animals each: control, HAP, BMP, and mixed BMP/HAP. A Critical-size defect of 4mm was made using a trephine in the calvarial bone and, after that, BMP and/or HAP was applied to the defect according to the grouping. Defects were evaluated radiographically and histologically using ImageJ color analyzer software at 4 weeks postoperatively.
  
  
  RESULTS
  The histological data were more precise than the radiologic data due to the white color of the porous-type HAP material. The highest radiopacity was noted in the mixed BMP/HAP group (162.07±9.06), followed by the HAP group (133.15±21.8), then the BMP group (100.79±8.27), and, lastly, the control group (54.45±8.39). After subtracting the white background and using ImageJ for histological analysis, the highest rate of osteochondrogenesis was in the mixed BMP/HAP group (85.29%±8.21), and then the BMP group (77.34%±7.39), followed by the HAP group (59.82%±11.23), and, lastly, the control group (40.27%±7.44). Differences in the values between groups were then analyzed using confidence intervals (CI) of 95 and 99%.
  
  
  CONCLUSIONS
  Within 4 weeks, the mixed BMP/HAP group showed the highest level of bone induction, especially compared to the BMP group, but this was non-significant; even with a 95% CI, the result was negative. This reveals that BMP alone can be applied, with a final result the same as that seen in the mixed BMP/HAP group. BMP and HAP, both being osteoinducting agents, even though they differ from a material classification point of view, have a positive effect on osteogenesis.
authors: Kansai Medical University, Department of Plastic and Reconstructive Surgery, 2-3-1 Shinmachi, Hirakata, Osaka, Japan. frederik.zefanya@gmail.com,
authors: Frederik Zefanya
authors: FZ
authors: Notodihardjo
authors: Natsuko
authors: N
authors: Kakudo
authors: Satoshi
authors: S
authors: Kushida
authors: Kenji
authors: K
authors: Suzuki
authors: Kenji
authors: K
authors: Kusumoto
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D001847:Bone Diseases / Q000188:drug therapy / Q000601:surgery*; D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use*; D001861:Bone Regeneration / Q000187:drug effects*; D018786:Bone Substitutes / Q000627:therapeutic use*; D020219:Chondrogenesis / Q000187:drug effects; D017886:Durapatite / Q000627:therapeutic use*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008648:Mesoderm / Q000473:pathology; D010006:Osteoblasts / Q000473:pathology; D010012:Osteogenesis / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012886:Skull / Q000187:drug effects / Q000601:surgery*; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D018786:Bone Substitutes; D017886:Durapatite