1. Root Formation
• Takes place as the crown is completely shaped and the tooth begins to erupt
therefore the tooth forms from the “top down” – i.e. crown to root
• Root formation is through the formation of a cervical loop
• The CL is the most cervical portion of the enamel/dental organ – two layers
consisting of IEE and OEE
• The CL begins to grow down into the dental sac it forms a Hertwig's root
sheath grows down to encompass all but the basal portion of the pulp this
sheath shapes the root and induces dentin formation in the root area by the
ODs of the dental papilla
• This sheath lacks the stellate reticulum and stratum intermedium
• The root of the tooth is composed by dentin and cementum
• Dentin forms when the outer cells of the dental papilla are induced to
differentiation into ODs
• Similar to what occurs at the crown area
• Influenced by Hertwig’s root sheath
• The ODs then undergo dentinogenesis and secrete predentin
• After dentin formation – the BM disintegrates along with the Hertwig’s
sheath
4
The root is beginning to form as an extension of the inner
and outer dental epithelia in the cervical loop region
(circles) which form a bilayered structure called
Hertwig’s epithelial root sheath.