Tooth Eruption & Exfoliation

• The aim is to enable students to understand the sequence and importance of the chronology for eruption and exfoliation of primary and secondary dentition.
• To know the terminology used in the eruption and exfoliation sequence
• Understand the reasons why it is important to be able to differentiate normal vs abnormal

Learning Outcomes

• Know calcification dates, eruption dates, and exfoliation dates for primary and permanent dentition.
• Primary teeth hold a place in the jaw for permanent teeth as they move into place when primary teeth are shed.
• Understand the normal sequence of exfoliation and eruption to determine deviations.
• Girls' dentition generally erupts sooner than boys'.

Impact of Systemic or Local Issues on Permanent Dentition

• Systemic issues may cause delayed eruption, non-formation of teeth, or Molar-Incisor Hypomineralisation (MIH).
• Systemic factors include genetic issues, nutrition, hormonal or endocrine disorders and pyrexia due to systemic infections.
• Diseases like kidney disease or cancer, medications like chemotherapy or phenytoin, fluorosis, and low birth weight or smoking environments can impact permanent dentition.
• Local factors can cause delayed eruption, non-formation, or Molar-Incisor Hypomineralisation (MIH).
• These factors include early loss of deciduous teeth, impacted or misplaced teeth, and missing dentition, usually maxillary 2s and mandibular 8s.
• Gum overgrowth, oral clefts and eruption cysts can affect the development of teeth
• Trauma, supernumerary teeth, gingival hyperplasia/fibrosis, oral clefts, and eruption cysts are also local factors.

Order and Timing of Deciduous Teeth

• The chronology and timing of deciduous dentition:
  • Maxillary first inscisor calcification occurs 3-4 months in utero, crown is completed in 4 months, eruption at 7.5 months, root complete in 1.5-2 years
  • Maxillary second incisor calcification occurs 4-5 months in utero, crown completion at 5 months, eruption at 8 months, and root completion at 1.5-2 years.
  • Maxillary canine calcification at 5 months in utero, crown complete at 9 months, erupts 16-20 months, root complete in 2.5-3 years.
  • Maxillary first molar calcification at 5 months in utero, crown is completed at 6 months, eruption occurs at 12-16 months, and root complete in 2-2.5 years.
  • Maxillary second molar calcification is at 6 months in utero, crown completed in 10-12 months, erupts at 1.75-2.5 years, root completed in 3 years.
• Mandibular first incisor: calcification at 4-5 months in utero, crown complete in 4 months, erupts at 4 months, and root completes in 1.5-2 years
  • Mandibular second incisor: calcification at 4-5 months in utero, 4.5 months to complete crown, eruption at 4.5 months, root completes in 1.5-2 years
  • Mandibular canine calcification at 5 months in utero, 9 months to complete the crown, eruption in 9 months, root completes in 2.5-3 years
  • Mandibular first molar: calcification at 5 months in utero, 6 months to complete its crown, erupts in 6 months, with root completion in 2-2.5 years.
  • Mandibular second molar: calcification at 6 months in utero, crown complete in 10-12 months, erupts in 10-12 months, and root completion in 3 years.

Order of Eruption - Deciduous Dentition

• Maxillary eruption order: A-B-D-C-E.
• Mandibular eruption order: A-B-D-C-E.

Tooth Eruption Chronology – Permanent Dentition

• Maxillary central incisor calcification occurs 3-4 months after birth, crown completion at 4-5 years, eruption at 7-8 years, root complete in 10 years.
• Maxillary lateral incisor calcification occurs 10-12 months after birth, crown completion in 4-5 years, eruption at 8-9 years, and root completed in 11 years.
• Maxillary canine calcification occurs 4-5 months after birth, crown is completed in 6-7 years, eruption at 11-12 years, and root completed in 13-15 years.
• Maxillary first premolar calcification is 18-21 months after birth, crown completed in 5-6 years, erupts at 10-11 years, and root completed in 12-13 years.
• Maxillary second premolar calcification in 2-2.5 years, crown completed in 6-7 years, erupts at 10-12 years, and root completed at 12-14 years.

Permanent Mandibular

• Mandibular central incisor calcification 3-4 months after birth, crown at 4-5 years, erupts 6-7 years, and root is complete at 9 years.
• Mandibular lateral incisor calcification is 3-4 months after birth, crown completed at 4-5 years, erupts 7-8 years, and the root is complete at 10 years.
• Mandibular canine calcification occurs 4-5 months after birth, crown completes in 6-7 years, erupts at 9-10 years, and the root completes between 12-14 years.
• Mandibular first premolar development begins at 21 months to 2 years, crown completes at 5-6 years, erupts between ages 10-12 and completes root development 12-13 years
• Second premolar calcification at 2.25-2.5 years, crown completion 6-7 years, erupts 11-12 years and the root is completed at 13-14 years

Upper and Lower Molars

• Upper 1st molar initial calcification occurs birth/slighly before, crown completed in 2.5 - 3 years, erupts between 6-7 years, and root is complete at 9-10 years
• Upper 2nd molar initial calcification in 2.5-3 , crown completion in 7-8 years, erupts between 12-13 years, root completion in 14-16 years
• Upper 3rd molar calcification 7-9 years, crown is made by 12-16, eruption occurs 17-21 years, root completion 18 - 25 years
• Lower 1st molar: Initial calcification at birth/slighly before, the crown completion at 2.5-3 years, as the eruption between 6-7 years, and root made at 9-10years
• Lower 2nd molar initial calcification at 2.5-3 years, crown completion at 7-8 years, erupts between 11-13 years, and root is complete at 14-15 years of age
• Lower 3rd molar initial calcification 8-10 years, crown complete at 12-16 years, erupts at 17-21 years, root complete from 18 -25 years

Mixed Dentition & Radiographs

• Impacted teeth, unerupted or ectopically placed, and tooth infections can affect the permanent dentition.
• Trauma to primary teeth can also affect the permanent successor.
• Order of eruption of permanent dentition:
  • Maxillary: 6-1-2-4-5-3-7-8
  • Mandibular: 6-1-2-3-4-5-7-8