Dentin Characteristics
Incremental lines:
Von Ebner lines
Appearance:
- Banding along the dentinal tubules
- Perpendicular to dentinal tubules
Cause:
- The dentine formation occurs incrementally ~ 4mm / day.
- A change of collagen fiber orientation was seen more clearly after 5-day cycle of this daily deposition
Appearance:
In longitudinal ground sections, they appeared as dark bands.
Cause:
- Changes in the coloration of the dentin
- Periods of illness
- Changes of body metabolism or inadequate nutrition
Tom's granular layer:
Appearance:
- Black granules.
- Only clear in ground section.
- Increasing in the granules occurs from the CEJ to the apex of the tooth
- Visible in radicular (root) dentin near DCJ
Cause:
- Looping back of dentinal tubules
- Special arrangement of collagen & non- collagenous proteins between dentin and cementum
Interglobular dentine:
Appearance:
- This pattern of mineralization is best seen in circumpulpal dentin just below mantel dentin, because of the globular pattern of mineralization in this region
- In a ground section of dentin, the less-calcified areas of dentin appear as irregularly shaped crescents
Cause:
- Areas of unmineralised or hypomineralised dentin, where globular zones of mineralization defect to fuse into a homogenous mass within mature dentin
- Common in persons with Vitamin D deficiency or high levels of Fl- at the time of dentinogenesis
Changes in dentinal tubules:
Dead tracts
Appearance:
- Appears dark in ground sections
- Mostly in the coronal Dentine
Cause:
- They occur as age change
- A severe injury or stimulus causes the odontoblasts to be destroyed in the region
- When dentin is damaged, odontoblastic processes die or retract leaving empty dentinal tubules
Sclerotic dentine
Appearance:
- Dentin appeared glassy and becomes translucent
- Is most common in the apical third of the root
Causes:
- Increase with age
- Due to noxious stimuli as in chronic caries
- Irritated odontoblasts forms sclerotic dentin as a protective wall