PMC

AFM topographic images of the occlusal area of enamel near the DEJ. A: WT male, B: D4 male, C: WT female, D: D4 female. More pores were apparent in the D4 male.

A: Schematic drawing of examined area on sagittal section of first molar. B: optical microscopic image (male WT) squares show the examined area in A. C: SEM (backscattered) showing porous structure of enamel.

Pore size (μm²), by tissue type, mouse type, and sex. Plotted are means (95% confidence interval), per tissue type, over 3 male mice at 8 positions; 4 female mice at 8 positions. Pore size is larger in D4 than WT, after controlling for tissue type and sex (P=0.03). Pore size is larger in enamel near the DEJ than in the mid-enamel region (P<0.001).

a. Percentage of 1000 μm² field occupied by pores, by tissue type, mouse type, and sex. Plotted are means (95% confidence interval), per tissue type, over 3 male mice at 8 positions; 4 female mice at 8 positions. Pore areas in enamel are greatest in D4 male mice, in which pores occupied 3.3-fold more area near the DEJ than in mid-enamel (p<0.001).
b. Enamel near the DEJ: Percentage of 1000 μm² field occupied by pores, by mouse type, tissue location, and mouse sex. Plotted are means (95% confidence interval), per tissue type, over 3 male mice at 2 cervical, 3 proximal, and 3 occlusal positions; and 4 female mice at 2 cervical, 3 proximal, and 3 occlusal positions. Male teeth are more porous in the proximal and occlusal regions than in the cervical region, whereas female teeth are more porous in the cervical and proximal regions than in the occlusal region (tests of variation by position: male, P=0.097; female, P=0.042).

In situ hybridization of the TGF-β mouse teeth. Molars showed osteocalcin expression in the dentin (d) and cementum (c) layers (A). Antisense control shows no staining (B). However, since mouse molar enamel development is complete in 2 month old mice, ameloblasts (a) were no longer present. Osteocalcin in situ hybridization (C) and control (D) of incisors show the cervical loop (CL) area where enamel formation is initiated up to the enamel maturation stage. At all stages of enamel formation only the dentin is positive for osteocalcin mRNA, indicating that alterations in the enamel of the TGF-β mice are secondary to TGF-β₂ overexpression by the odontoblasts (o), pulp (p).

These panels show an example of how the AFM images were processed with Scion Image™. A: Topographic image captured by AFM. A 20×50 μm area (shown as white outlined box) along the DEJ was selected. B) The z axis value is shown in the chromatic scales to the right of the image, with darker colors showing lower topography, representing pores in the enamel. C) The Scion image system was used to identify pores by color, with pores defined as small dark spots. When capturing the images of pores in the lighter elevated regions, larger concave areas were falsely identified (green outlined area). These areas were manually deleted and a second image (C2) was made of the pores in the darker concave regions. These two images were transferred to a black scale (binarized) and the total number and size (area) of the pores were counted and recorded.