How a root of tooth is developed.

2. ROOT FORMATION OF A TOOTH
DURING ODONTOGENESIS
By Maier Zaman Khan
Class no. 05

3. LEARNING OBJECTIVES
 Steps of root formation
 Epithelial Diaphragm
 Root formation in Single Rooted vs Multi rooted Tooth

4. 1.STEPS OF ROOT FORMATION
Formation of Hertwigs Epithelial Root Sheath
Deposition Of Dentin
Degeneration Of HERS
Deposition Of Cementum

5. Formation of HERS
• Initiates after the Enamel and Dentin deposition of the Crown has reached the cervical loop
• Originates at the Cervical loop and grows into the underlying ectomesenchyme separating Dental
Papilla from Dental Sac
• Formed by the extension of Inner Enamel Epithelium and Outer Enamel Epithelium
Function Of HERS
• It sends signals to the Dental Papilla cells
• The Dental Papilla cells on receiving the signals differentiate into Odontoblasts

7. Deposition Of Dentin
• Once the Dental Papilla cells differentiate into Odontoblasts , they start the deposition of Dentin
• Once Dentin Deposition Starts , the function of HERS is over

8. Degeneration Of HERS
• Once Dentin Deposition Starts , The function of HERS is over.
• The cells of HERS undergo degeneration.
• The degeneration of HERS is not complete and leaves remnants of cells.
• These remnants are called “Rests Of Malassez”.
• These are dormant cells.
• May give rise to pathologies like “cysts” and “tumors”.

10. Deposition Of Cementum
• After the degeneration of HERS, The Dental Sac cells come in direct contact with the Dentin.
• This contact of cells of Dental Sac with the Dentin differentiates them Into Cementoblasts.
• These Cementoblasts start depositing Cementum.
• In this way Root formation is completed.

12. 2.EPITHELIAL DIAPHRAGM
• The HERS bends and grows horizontally to form an “Epithelial Diaphragm”.
• This Epithelial Diaphragm does not meet in the middle and thus reduces the size of the Cervical
Opening to form the “Apical Foramen”.

13. 3.ROOT FORMATION IN SINGLE VS MULTI ROOTED
TEETH
• In a single rooted tooth, the cervical opening is one which gives rise to a single root
• In a multi rooted tooth ,however, the Epithelial Diaphragm grows in extensions to form two or three
cervical openings which give rise to multiple roots.

15. THANK YOU