• Admin
  • 9 January, 2022

Basics of Human Teeth - Here's What you Must Know

Human oral cavity comprises of 32 teeth which includes 4 wisdom teeth. The teeth are mineralized bone-like structures projecting from the alveolar processes of the jaws.  

Functions of the teeth includes:

  • Grind the food materials during mastication 
  • Teeth helps sometimes as a weapon 
  • Teeth boosts up the confidence by helping in speech and beautifies the face 

The humans are diphyodont, i.e., two sets of teeth develops in a human’s lifetime. The first set of teeth is called as primary or deciduous teeth. They begin to form prenatally about 14 weeks in intrauterine life and formation completes postnatally at about 3 years of age. They shed from the age of 5 and later on permanent teeth starts erupting.  

At first lower incisors erupt approximately 6 months after birth and the last milk tooth to erupt is molars at approximately 2 years. The first permanent tooth erupts at approximately 6 years and continues until about 17 years of age. The wisdom teeth are less predictable and if they erupt, it is between the ages 17 and 25. If they fail to erupt, it is called as impacted teeth. 

Eruption of Deciduous Teeth – Approximate timeline 

  • Lower central incisors: 6 months 
  • Upper central incisors: 7 months 
  • Lateral incisors: 8–9 months 
  • First molar: 12 months (1 year) 
  • Canines: 18 months (1 year 6 months) 
  • Second molars: 24 months (2 years) 

Eruption of Permanent Teeth - Approximate timeline 

  • First molar: 6 years 
  • Medial incisors: 7 years 
  • Lateral incisors: 8 years 
  • First premolar: 9 years 
  • Second premolar: 10 years 
  • Canines: 11 years 
  • Second molars: 12 years 
  • Third molar (Wisdom tooth): 18–24 years 

Parts of a tooth includes:

The outermost enamel, followed by dentin and deep within is the pulp of the tooth. The root portion is covered by cementum. The tooth / teeth is located within the bony sockets of the jaw bone. It is surrounded by the periodontal ligament which comprises of cells and fibres. The pulp of the tooth contains the blood vessels and the nerves.  

The tooth is the hardest and chemically most stable tissue in the body. Hence, they are presented or fossilized after death for medicolegal purpose to identify the unrecognizable dead bodies.

Number of roots in all types of teeth:

  • Upper molars - 3 roots each (2 lateral and 1 medial) 
  • Lower molars - 2 roots each (1 anterior and 1 posterior) 
  • All other teeth except first upper premolar - 1 root 

 

Article by Dr. Siri P. B.

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