title: Effects of biglycan on physico-chemical properties of ligament-mineralized tissue attachment sites.
abstract: Matrix proteoglycans define matrix structure, mineralization, and resulting biomechanics of tissues and their attachment sites.
  
  
  OBJECTIVE
  We therefore investigated physical and (bio)chemical differences in enamel and periodontal tissues/attachment sites from mice that lack a specific nanoscale small leucine-rich proteoglycan (SLRPs) named biglycan (BGN).
  
  
  METHODS
  Experimental groups consisted of N=4, biglycan knockout (BGNKO) and N=5 wildtype (WT) 8-week-old, male C3H mice. Morphology, histochemical and mechanical analyses were performed through micro X-ray computed tomography (Micro XCT™), immunohistochemistry, and microindentation. Unless mentioned otherwise, all differences between BGNKO and WT were demonstrated to be statistically significant through Student's t-tests with a 95% confidence interval (P≤0.05).
  
  
  RESULTS
  Histomorphometry performed by using Micro XCT™ images indicated significantly higher BGNKO-enamel (0.46 ± 0.03mm(3)) and BGNKO-root (1.81 ± 0.10mm(3)) volumes compared to WT-enamel (0.37 ± 0.02mm(3)) and WT-root (1.65 ± 0.07mm(3)). BGNKO tooth size was relatively larger than WT mice, with no significant difference between skull sizes. Immunohistochemistry indicated BGN expression in the periodontal ligament (PDL), alveolar bone (AB), at the bone-PDL and cementum-PDL attachment sites in WT mice. Deeper AB resorption pits within interdental region of BGNKO specimens compared to WT resulting in significant differences in PDL-space of BGNKO (93 ± 13μm) and WT (74 ± 11μm) were observed. Microhardness of BGNKO-enamel (2.46 ± 0.60GPa) and BGNKO-AB (0.52 ± 0.10GPa) was significantly lower than WT-enamel (2.67 ± 0.60GPa) and WT-AB (0.54 ± 0.10GPa).
  
  
  CONCLUSIONS
  Results indicate that BGNKO-mice exhibit significant differences in tissue properties compared to WT-mice.
authors.affiliation: Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, University of California San Francisco, San Francisco, CA 94143, United States.
authors.forename: R
authors.initials: R
authors.lastname: Chiu
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.forename: R P
authors.initials: RP
authors.lastname: Herber
authors.forename: S J
authors.initials: SJ
authors.lastname: Marshall
authors.forename: M
authors.initials: M
authors.lastname: Young
authors.forename: S P
authors.initials: SP
authors.lastname: Ho
mesh_terms: D016301:Alveolar Bone Loss / Q000378:metabolism; D000818:Animals; D058578:Biglycan / Q000737:chemistry / Q000378:metabolism*; D003739:Dental Cementum / Q000378:metabolism*; D003743:Dental Enamel / Q000033:anatomy & histology / Q000378:metabolism*; D003746:Dental Enamel Proteins / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D010513:Periodontal Ligament / Q000378:metabolism*; D014057:Tomography, X-Ray Computed; D014074:Tooth Calcification; D014092:Tooth Root / Q000033:anatomy & histology / Q000378:metabolism*
chemical_list: D058578:Biglycan; D003746:Dental Enamel Proteins; D016326:Extracellular Matrix Proteins