Dentin Structure and Composition
- Dentin consists of microscopic channels called dentinal tubules.
- Dentin contains odontoblast processes and dentinal fluid.
- Dentin has branching canalicular systems of different sizes.
- Dentin is composed of 70-72% inorganic materials, mainly hydroxyapatite.
- It contains 20% organic materials, primarily collagen type 1.
- Dentin also contains dentin-specific proteins and ground substance.
- Water makes up 8-10% of dentin.
- Dentin is porous and yellow-hued.

Dentin Properties and Functions
- Dentin is softer than enamel but provides support for it.
- It decays more rapidly than enamel if not properly treated.
- Dentin has a degree of permeability, which can increase pain sensation and tooth decay.
- Dentin has elastic properties, preventing enamel fracturing.
- Changes in dentinal fluid contribute to dentinal hypersensitivity.

Dentin Types
- Dentin is classified into three types: primary, secondary, and tertiary.
- Secondary dentin is formed after root formation is complete.
- Tertiary dentin develops as a result of a stimulus, such as carious attack or wear.

Dentinogenesis
- Dentinogenesis is the process of dentin formation in teeth.
- It involves the differentiation and maturation of odontoblasts, which are responsible for producing dentin.
- Dentinogenesis is regulated by various growth factors and signaling molecules.
- The mineralization of dentin occurs through the deposition of hydroxyapatite crystals.
- Dentinogenesis is essential for tooth development and repair.

Dentin Defects and Conditions
- Dentinal sclerosis is a change in the structure of teeth characterised by calcification of dentinal tubules.
- Dentinal sclerosis affects primary dentin.
- Dentinogenesis imperfecta is a genetic disorder that affects the development of dentin.
- It is characterised by the abnormal formation of dentin, resulting in weak and discolored teeth.
- Odontoblasts are specialised cells found in the pulp of teeth.
- They are responsible for the formation of dentin and the maintenance of tooth vitality.
- Tooth development begins during embryogenesis and continues throughout childhood and adolescence.
- Tooth development is regulated by a complex interplay of signaling pathways and genetic factors.
- Dentin is a mineralised tissue that forms the bulk of the tooth structure.
- The dentin substrate provides mechanical support to the tooth and helps in transmitting sensory stimuli.