title: Evaluation of BSP expression and apoptosis in the periodontal ligament during orthodontic relapse: a preliminary study.
abstract: OBJECTIVE
  To examine the expression of bone sialoprotein (BSP) and apoptosis in an in vivo orthodontic relapse model.
  
  
  METHODS
  Male mice (10-12 weeks old), either transgenic [green fluorescent protein (GFP) driven by the BSP promoter] or wild type, were used in this study. To achieve orthodontic tooth movement (OTM), maxillary right first molars were moved mesially using closed-coil springs. Animals were divided into an OTM group (14 days continuous orthodontic force - 11 animals) or Relapse group (10 days of force application followed by 4 days of relapse - 8 animals). The control group was comprised of the contralateral maxillary molars. The periodontal ligament (PDL) was analyzed in areas of compression and tension for transgenic expression, osteoclast localization, and the presence of apoptotic cells.
  
  
  RESULTS
  There was a significant decrease in GFP-labeled cells on the compression and tension sides of the PDL in the OTM group compared with control. In the relapse group, GFP-labeled cells were significantly decreased only on the old compression side. Osteoclasts were localized on the compression side of the OTM group, whereas in the Relapse group, they were present on both sides. PDL apoptosis significantly increased on the compression side in OTM and Relapse groups.
  
  
  CONCLUSIONS
  Both OTM and Relapse groups exhibited a decreased number of GFP-labeled cells in areas of compression and tension. There was significant PDL apoptosis in regions under compressive forces following OTM and to a lesser extent following relapse.
authors.affiliation: Private Practice, Shrewsbury, MA, USA.
authors.forename: A
authors.initials: A
authors.lastname: McManus
authors.forename: A
authors.initials: A
authors.lastname: Utreja
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: Z
authors.initials: Z
authors.lastname: Kalajzic
authors.forename: W
authors.initials: W
authors.lastname: Yang
authors.forename: R
authors.initials: R
authors.lastname: Nanda
authors.forename: S
authors.initials: S
authors.lastname: Wadhwa
authors.forename: F
authors.initials: F
authors.lastname: Uribe
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000539:Alveolar Process / Q000737:chemistry / Q000473:pathology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology; D003739:Dental Cementum / Q000737:chemistry / Q000473:pathology; D020287:In Situ Nick-End Labeling; D058574:Integrin-Binding Sialoprotein / Q000032:analysis*; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D008437:Maxilla / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D008963:Molar / Q000473:pathology; D010006:Osteoblasts / Q000737:chemistry / Q000473:pathology; D010010:Osteoclasts / Q000473:pathology; D010011:Osteocytes / Q000737:chemistry / Q000473:pathology; D010513:Periodontal Ligament / Q000737:chemistry / Q000473:pathology*; D011312:Pressure; D012008:Recurrence; D013314:Stress, Mechanical; D000071681:Tartrate-Resistant Acid Phosphatase; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: C546872:Ibsp protein, mouse; D058574:Integrin-Binding Sialoprotein; D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase
keywords: apoptosis; osteoblast; osteoclast; periodontal ligament; tooth movement