What structure is responsible for root development?
Cervical loop
What does the cervical loop consist of?
IEE (inner enamel epithelium) and OEE (outer enamel epithelium)
How is Hertwig’s epithelial root sheath formed?
The cervical loop elongates away from the crown enclosing more dental papilla.
Why isn’t enamel formed in the root if you have IEE and OEE?
The other cell linings are not present (Stellate reticulum and stratum intermedium) so the body recognizes this and will not form enamel.
What are the functions of Hertwig’s epithelial root sheath?
- Induction of Odontoblasts
- Determines size, shape, and # of roots.
- After roots are completed the sheath disintegrates and becomes “epithelial rests of Malassez”
How is cementum formed in the root?
- Disintegration of HERS.
- Contact b/w undifferentiated mesenchymal cells with newly formed dentin.
- Immature cementoblasts
- Secretion of a matrix called cementoid
- Maturation of the matrix (hydroxyapatite) where cementoblasts are trapped and become cementocytes which eventually become cementum
What is HERS?
Hertwig’s epithelial root sheath.
What is the origin of the periodontal ligament?
Ectomesenchyme from the dental sac.
How is the PDL formed?
- Collagen fibers are organized into bundles.
2. The ends of the groups insert into the outer cementum and surrounding alveolar bone.
True of False; The PDL makes humans theocodonts.
True
What is the name for a special ligament attachment from root to bone?
gomphosis
