Skip to main content
. Author manuscript; available in PMC: 2013 Jan 1.
Published in final edited form as: Bone. 2011 Nov 4;50(1):265–275. doi: 10.1016/j.bone.2011.10.031

Figure 8.

Figure 8

Diagrammatic representation of the formation of reactionary dentin.

  • Circular and uniformly distributed tubules are present in healthy teeth with odontoblast expression of TLR-2 but not TLR-4. DSP and MMP-2 are sparsely distributed.
  • During extension of caries, LPS expressed by Gram negative bacteria triggers the TLR-4 signalling pathway which induces up-regulation of MMP-2, accompanied by up-regulation of TIMP-2 and MT1-MMP (down-regulation of Endo180 enhances MT1-MMP activity) resulting in cleavage of DSPP by activated MMP-2.
  • DSP cleaved from DSPP is deposited on newly synthesised collagen forming nucleation sites for hydroxyapatite crystal formation.
  • Low levels of TGF-β, released from dentin matrix and activated by bacterial acid or MMP-2, stimulate odontoblasts to increase collagen synthesis.