DENTITION & TOOTH ANATOMY

DENTITION 

• Teeth are small, calcified, hard whitish structures found in the mouth for mechanically breaking down items of food by cutting and crushing them.

• Humans usually have 20 primary(deciduous, baby or milk) teeth and 32 permanent (adult) teeth.

Teeth are classified as:

• Incisors

• Central incisors

• Lateral incisors

• Canines

• Premolars

• Molars

Teeth are the only part of human body that cannot repair itself.

Incisors

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  Present at the front of the mouth

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  These teeth have sharp edges and are adapted for cutting food into small, chewable pieces.

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  Humans have eight incisors, four incisors in the upper jaw and four in the lower jaw.

Canines- 

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  Also called as cuspids.

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  They are situated at the corners of the dental arches.

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  They have sharp, elongated and pointy surfaces.

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  Their function is to grip and tear food.

Premolars

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  Also called as bicuspids.

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  They are located behind the canines.

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  These teeth have a flat surface with ridges.

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  Adapted for crushing and grinding food into smaller portions.

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  Humans have eight premolars, two on each side of the jaw.

Molars 

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  They are the largest and strongest teeth.

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  They have large and flat biting surface.

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  Their function is to grind food.

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  Humans have 12 molars, 6 in each jaw.

Wisdom teeth

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  Also referred to as third molars.

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  They are the vestigial and final set of molars which comes in between the ages of 17 to 25.

Teeth are organized into two opposing arches:

1. Maxillary(upper)

2. Mandibular(lower)

• These can be divided down the midline into right and left.

• The normal permanent(adult) dentition comprises four incisors, two canines, four premolars and six molars in each jaw comprising 32 teeth.

The human dentition is composed of two sets of teeth: 

1. Primary

2. Permanent

• Primary dentition also called as deciduous teeth, baby teeth, milk teeth or primary teeth.

• Permanent dentition also called as secondary dentition or adult teeth.

 The primary teeth are grouped into four quadrants each containing two incisors, a         canine and two molars.

The primary dentition arises from 2 and a half years of age to 6-7 years of age.

• Mixed dentition- it is the stage where both primary and permanent teeth are present.

The deciduous dental formula

I 2/2 C1/1 M2/2 =10

The permanent dental formula

I 2/2 C1/1 P2/2 M3/3=16

TOOTH ANATOMY

• Each tooth has a crown and root portion.

• The crown portion is the part covered with enamel and the root portion is the part covered with cementum.

• The crown and root join at cemento- enamel junction or cervical line.

• The main bulk of tooth is composed of dentin.

• The pulp cavity contain the pulp tissue.

• The clinical crown -it is the erupted part ( crown or root) of the tooth seen in the mouth.

• The anatomical crown- it is the part of the tooth which is covered with enamel.

• The root portion of the tooth may be single with one apex as found in all anterior teeth and some of the premolars or multiple with a bifurcation or a trifurcation dividing the root portion into two or more roots as found in all molars and some premolars.

Parts of teeth

Your teeth are composed of four dental tissues:

Hard tissues: Enamel

                      Dentin

                      Cementum

Soft tissue: Pulp 

Dental tissues:

Enamel: the protective outer surface of the anatomic crown. 96% of it is composed of mineral and is the hardest tissue in the body.

Dentin: located in both the crown and root. It makes up the bulk of the tooth beneath the enamel and cementum. It lines the pulp cavity.

Cementum: this substance covers the surface of anatomic root.

Pulp: the central, innermost portion of the tooth. It functions during the life of the tooth.