Title: 3395 - Dentin Collagen Architecture Related to Site, Depth, and Aging
Arosha Weerakoon (Presenter)
University of Queensland
Ian Meyers, University of Queensland
Sandrine Roy, Translational Research Institute
Pauline Ford, University of Queensland
David Thomson, University of Queensland
Anne Symons, University of Queensland
Objectives: To test the null hypothesis that dentin collagen architecture does not change with site, depth or aging.
Background: Dentin is composed of mineral hydroxyapatite supported by a collagen scaffold. The collagen scaffold may vary with increasing age and dentin depth. Under polarized light, unstained collagen tissue sections emit birefringent colors in the visible light spectrum. The colors indicate collagen fiber thickness and density. Relatively thin fibers or loosely packed collagen emit short wavelength light (green-yellow-orange) while thick or tightly packed collagen fibers emit longer wavelengths (red, black-other).
Methods: Molars or premolars (N=5/group) were collected from Young (≤27 years) and Mature (≥52 years) patients, stored in phosphate buffered saline at 4°C, and gamma radiated. Teeth were sectioned mesio-distally, to reveal shallow (0.5-0.75 mm below the dentin-enamel junction) and deep (0.5-0.75 mm above pulp chamber roof) regions within the coronal dentin. Sectioned teeth were demineralized in EDTA, paraffin embedded, and stained using Picrosirius Red F3BA (PSR) to enhance collagen birefringence. Stained sections were observed under a Brightfield polarized light microscope (20x). Digital Images were analyzed using NIS elements BR Software to quantitate light wavelength birefringence (green, yellow, orange, red & black/other). The colors within each image were used to compare dentin collagen architecture.
Results: The median ratio of red and black/other to green, yellow and orange in dentin indicated that there was almost twice as much red and black/other in mature dentin (1.91 (0.76, 4.64) when compared to young dentin (0.92 (0.4, 2.55), irrespective of depth and site.
Conclusions: PSR stained deep dentin observed under polarized light indicates mature dentin collagen contains larger fibers or is more densely packed compared with young dentin. The PSR stain combined with polarized light microscopy is a novel and viable method to observe and quantifying variations in dentin collagen architecture.
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE