title: Expression of TGF-beta1, osteonectin, and BMP-4 in mandibular distraction osteogenesis with compression stimulation: reverse transcriptase-polymerase chain reaction study and biomechanical test.
abstract: OBJECTIVE
  This study compared the levels of transforming growth factor-beta1 (TGF-beta1), osteonectin, and bone morphogenetic protein-4 (BMP-4) expression in regenerated bone in a rabbit mandible that had undergone conventional distraction osteogenesis (DO) with those in regenerated bone from a modified DO technique with compression stimulation.
  
  
  METHODS
  A total of 42 rabbits were used in this reverse transcriptase-polymerase chain reaction study. In the control group, distraction was performed at 1 mm/day for 8 days. In the experimental group, overdistraction was performed for 10 days, followed by a 3-day latency period and 2 days of compression to achieve the same amount of DO. Three rabbits per subgroup were killed at 0, 5, 13, 20, 27, 34, and 41 days after the initial osteotomy. The levels of TGF-beta1, osteonectin, and BMP-4 in the bone regenerates were measured by reverse transcriptase-polymerase chain reaction. A biomechanical microhardness test was also performed in 8 rabbits as a separate experiment.
  
  
  RESULTS
  Reverse transcriptase-polymerase chain reaction revealed a greater level of TGF-beta1 in the experimental group immediately after applying the compression force that continued for 2 weeks. The level then decreased to that of the control group at 3 weeks. The greater level of osteonectin in the experimental group after compression than that in the control group continued for 3 weeks. In the experimental group, the level of BMP-4 increased immediately after compression. However, the level in the control group decreased. The microhardness ratio of distracted bone to normal bone on the cortex was statistically different at 0.47 in the control group and 0.80 in the experimental group (P = .049) at 55 days after osteotomy.
  
  
  CONCLUSIONS
  The effectiveness of the new DO technique with compression stimulation was confirmed by the gene expression study and the biomechanical test findings.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Pusan National University School of Dentistry, Pusan, Republic of Korea. kuksjs@pusan.ac.kr
authors.forename: Uk-Kyu
authors.initials: UK
authors.lastname: Kim
authors.forename: Seong-Jin
authors.initials: SJ
authors.lastname: Park
authors.forename: Wook-Jin
authors.initials: WJ
authors.lastname: Seong
authors.forename: Jun
authors.initials: J
authors.lastname: Heo
authors.forename: Dae-Seok
authors.initials: DS
authors.lastname: Hwang
authors.forename: Yong-Deok
authors.initials: YD
authors.lastname: Kim
authors.forename: Sang-Hun
authors.initials: SH
authors.lastname: Shin
authors.forename: Gyoo-Cheon
authors.initials: GC
authors.lastname: Kim
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D055415:Bone Morphogenetic Protein 4 / Q000096:biosynthesis* / Q000235:genetics; D001861:Bone Regeneration / Q000502:physiology*; D002146:Bony Callus / Q000378:metabolism; D019245:Compressive Strength; D003799:Dental Stress Analysis; D015870:Gene Expression; D006244:Hardness; D008334:Mandible / Q000378:metabolism / Q000601:surgery*; D019647:Oral Surgical Procedures / Q000379:methods*; D019857:Osteogenesis, Distraction; D015676:Osteonectin / Q000096:biosynthesis* / Q000235:genetics; D010027:Osteotomy / Q000379:methods; D010812:Physical Stimulation; D011817:Rabbits; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D055415:Bone Morphogenetic Protein 4; D015676:Osteonectin; D053773:Transforming Growth Factor beta1