Elevated TGF-beta2 signaling in dentin results in sex related enamel defects.
Initiation of enamel formation requires reciprocal signaling between epithelially and mesenchymally derived cells.


OBJECTIVE
In this study, we used a transgenic mouse model which drives overexpression of an activated form of TGF-beta2 under control of the osteocalcin promoter, to investigate the role of TGF-beta2 in the dental mesenchyme, on enamel formation.


METHODS
Dentin and enamel were imaged by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Dentin mechanical properties were characterized for hardness and elasticity, following nanoindentation with a modified AFM. Pores found in enamel were quantified and compared using image analysis software (Scion Imagetrade mark).


RESULTS
The elastic modulus of dentin was significantly reduced in the male TGF-beta2 overexpressor mice as compared to male wildtype mice, with no significant differences between female mice. Similarly, there were significantly more pores in enamel of the male transgenic mice as compared to male wildtype mice, with no significant differences between female mice. In situ hybridization of the continuously erupting incisor confirmed that osteocalcin expression was limited to the odontoblast cell layer at all stages of tooth formation.


CONCLUSIONS
TGF-beta2 overexpression in the dentin matrix, results in sex-linked differences in dentin and enamel formation.
Saeki
Kuniko
K
Preventive and Restorative Dental Sciences, University of California, San Francisco, Box 0758, 707 Parnassus Ave, San Francisco, CA 94143-0758, USA.
Hilton
Joan F
JF
Alliston
Tamara
T
Habelitz
Stefan
S
Marshall
Sally J
SJ
Marshall
Grayson W
GW
Denbesten
Pamela
P
D000566:Amelogenesis / Q000502:physiology; D000818:Animals; D003743:Dental Enamel / Q000002:abnormalities* / Q000648:ultrastructure; D003804:Dentin / Q000502:physiology* / Q000648:ultrastructure; D004195:Disease Models, Animal; D004548:Elasticity; D005260:Female; D006244:Hardness; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008648:Mesoderm / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D009804:Odontoblasts / Q000502:physiology; D009805:Odontogenesis / Q000502:physiology; D015675:Osteocalcin / Q000502:physiology; D016062:Porosity; D012737:Sex Factors; D015398:Signal Transduction / Q000502:physiology*; D053781:Transforming Growth Factor beta2 / Q000502:physiology*
D053781:Transforming Growth Factor beta2; D015675:Osteocalcin