Morphology of the Deciduous Maxillary First Molar

Timeline of Development

• First evidence of calcification: 15 weeks in utero
• Enamel completion: 6 months
• Eruption into oral cavity: 16 months
• Root completion: 2.5 years
• Exfoliation: ~10 years, replaced by maxillary first premolar

Tooth Notation Systems

Maxillary First Molar (Deciduous)

• Palmer Notation System:
  • Right: B
  • Left: I
• FDI Notation System:
  • Right: 54
  • Left: 64
• Universal Notation System:
  • Right: D
  • Left: D (with different symbols for right and left side)

Morphological Features

Buccal Aspect

• Widest measurement at contact areas
• Narrow at the cervical portion
• Smooth buccal surface, minimal developmental grooves
• Roots:
  • Three roots: Mesial, Distal, Lingual (Palatal)
  • Roots are cylindrical, long, and widely separated
  • Distal root is shorter than mesial roots
  • Division begins just below the cemento-enamel junction
  • Root trunk is not well-developed

Lingual Aspect

• Crown converges towards the lingual side
• Mesio-distal width is less on the lingual side
• Part of mesial and distal surfaces visible
• Cusps:
  • Mesio-lingual cusp: Most prominent
  • Disto-lingual cusp: Short and rounded (sometimes missing)
  • Three cusp type: One lingual cusp, two buccal cusps (if disto-lingual cusp is missing)
• Lingual root is largest and extends prominently lingually

Mesial Aspect

• Mesio-lingual cusp is longer and sharper than mesio-buccal cusp
• Pronounced convexity at the cervical third of the buccal surface
• Cervical line curves towards the occlusal surface
• Lingual root curves sharply buccally above the middle third

Distal Aspect

• Narrow buccal-lingual width of the crown
• Part of buccal and lingual aspects visible
• Cusps:
  • Disto-buccal cusp: Long and sharp
  • Disto-lingual cusp: Small and rounded
• Cervical line extends nearly straight from buccal to lingual side
• Bucal surface and apical area of mesio-buccal root visible

Occlusal Aspect

• Crown converges towards lingual and distal sides
• Mesio-distal width greater buccally than lingually
• Fossae:
  • Central fossa
  • Mesial triangular fossa
  • Distal triangular fossa
• Grooves:
  • Central developmental groove
  • Supplementary grooves arising from central groove
• Marginal Ridges:
  • Mesial marginal ridge: Thick and well-developed
  • Distal marginal ridge: Thin, small, and poorly developed

Additional Information

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• Instagram handle provided at the end of the lecture