IADR Abstract Archives

Gender Differences in an Altered Decreased Masticatory TMJ Loading Model

Objectives: Greater understanding of mechanical loading and estrogen regulation of mandibular chondrocyte differentiation is critical for regenerative stem cell therapies and to gain further understanding of the temporomandibular joint (TMJ) disease process. The goal of this of study was to determine if there are gender differences in chondrocyte proliferation, cortical mineral apposition rate, condylar cartilage thickness, and subchondral bone density in CD-1 mice exposed to an altered decreased masticatory TMJ loading model.

Methods: 21-day-old male (n=32), female (n=32) CD-1 mice were divided into two groups. The mice were fed either a normal pellet diet (normal loading) or a soft diet and had their incisors trimmed out of occlusion (altered loading) for 4-6 weeks. Bone apposition rate was determined by xylenol orange and calcein double labeling. Chondrocyte proliferation was determined by BrDu immonohistochemistry. Micro-CT analysis was performed on the subchondral bone to evaluate trabecular thickness. Cartilage thickness was determined by measuring sections of the condyle that had been stained with Safranin O and Fast green in photoshop.

Results: Altered loading for 4 weeks resulted in a statistically significant decrease in proliferation, cortical mineral apposition rate, and condylar cartilage thickness in male mice, but not in female mice. Additionally, altered loading for 4 weeks resulted in a statistically significant decrease in the trabecular thickness of the subchondral bone in both male and female mice. Unique to the female mice, when altered loading was extended to 6 weeks, trabecular thickness restored to the level of normal loaded controls.

Conclusions: The increased severity of decreased masticatory loading in male compared to female mice may suggest that estrogen and mechanical loading share a common pathway in the mandibular condylar head. A similar association has been previously defined in bone.

This work was supported by NIDCR K-22 DE017193 (SW)


IADR/AADR/CADR General Session
2009 IADR/AADR/CADR General Session (Miami, Florida)
Miami, Florida
2009
28
Craniofacial Biology
  • Chen, Jing  ( University of Connecticut, Farmington, CT, USA )
  • Amin, Susan  ( University of Connecticut Health Center, Farmington, CT, USA )
  • Kalajzic, Zana  ( University of Connecticut Health Center, Farmington, CT, USA )
  • Barasz, Jonah  ( University of Connecticut Health Center, Farmington, CT, USA )
  • Xu, Manshan  ( University of Connecticut Health Center, Farmington, CT, USA )
  • Yeh, Wei- Chang  ( University of Connecticut Health Center, Farmington, CT, USA )
  • Nanda, Ravindra  ( University of Connecticut Health Center, Farmington, CT, USA )
  • Wadhwa, Sunil  ( University of Connecticut Health Center, Farmington, CT, USA )
    • Oral Session
    TMJ, Orthodontic Tooth Movement
    04/01/2009