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Dental Anatomy Primer

The Mouth

The more you understand about the mouth and your child’s oral health the better you’ll be able to collaborate with your dentist to achieve your mutual goals of complete dental health and wholeness for your family.

The mouth serves as the first step of the digestive process by cutting, tearing and grinding food. The mouth is the only part of the digestive system with nerve endings that respond to taste, pain, pressure and temperature.

The tongue aids in swallowing and talking. The small projections on the tongue are called papillae. Some of the papillae on the tongue serves as taste buds.

Primary teeth

There are 20 primary teeth. They erupt, starting with the lower front teeth, around six months of age. The last primary teeth to erupt are the second molars, which present around 20-24 months of age.

Usually girl’s teeth erupt earlier than boy’s teeth and lower erupt earlier than corresponding upper teeth.

Primary teeth are important to keep healthy and in place because they are necessary to maintain the space for the permanent teeth that will be replacing them.

                            Eruption Shedding
Central incisor 7 1/2 mo. 7 1/2 yrs old
Lateral incisor 9 mo. 8 yrs old
Cuspid 18 mo. 11 1/2 yrs old
First molar 14 mo. 10 1/2 yrs old
Second molar 24 mo. 10 1/2 yrs old


  Eruption    Shedding
Central incisor 6 mo. 6 yrs old
Lateral incisor 7 mo. 7 yrs old
Cuspid 16 mo. 9 1/3 yrs old
First molar 12 mo. 10 yrs old
Second molar 20 mo. 11 yrs old

Permanent teeth

Permanent teeth follow the same basic sequence of eruption as primary teeth. Adults have a total of 32 teeth, including wisdom teeth.

The first permanent teeth usually erupt between six and eight years of age.

A primary tooth is lost prior to the eruption of each tooth except for permanent molars. These molars do not replace any primary teeth as they come in further back in the mouth than any primary teeth.

The permanent teeth are meant to last a lifetime.

Central incisor 7-8 yrs old
Lateral incisor 8-9 yrs old
Cuspid 11-12 yrs old
First bicuspid 10-11 yrs old
Second bicuspid 10-12 yrs old
First molar 6-7 yrs old
Second molar 12-13 yrs old
Third molar 17-21 yrs old

Central incisor 6-7 yrs old
Lateral incisor 7-8 yrs old
Cuspid 9-10 yrs old
First bicuspid 10-12 yrs old
Second bicuspid 11-12 yrs old
First molar 6-7 yrs old
Second molar 11-13 yrs old
Third molar 17-21 yrs old

The Tooth

Crown: The portion of the tooth above the gumline.

Neck: The intersection between the crown and root of the tooth.

Root: The portion of the tooth that extends into the jaws. The root forms the anchorage component of the tooth.

Enamel: Enamel forms the outer shell of the tooth above the gumline. Enamel is the hardest substance in the body, capable of withstanding unbelievable forces. Hard but brittle enamel does not heal like a broken bone. Tremendous care should be exercised in maintaining the health of this tissue.

Cementum: Cementum forms the outer coating of the root of the tooth. Its softer  more porous surface helps anchor the tooth to the jaw bones.

Dentin: Dentin is a bone like substance that forms the substructure of the tooth.
Pulp: The pulp contains blood vessels, nerves, and connective tissue. It is located beneath the dentin and extends through the root to the middle portion of the crown.

Periodontal Ligament: The PDL consists of connective tissue fibers that attach the root to the alveolar socket. The built in shock absorbing characteristics of this tissue allow the tooth to withstand the exceptional forces during biting and chewing.
Alveolar Bone: The hard tissue that forms the jaw bones.

Gingiva: Commonly referred to as the gums. It covers the bone and hugs the necks of the teeth.


These single rooted teeth are the front teeth in the upper and lower jaws. They are broad and flat with thin edges. These teeth are good for cutting. Typically there are four upper and four lower incisors. The pair at the center are called centrals and adjacent to them are the incisors called laterals.


Also called cuspids these single rooted teeth are adjacent to the incisors and form the corners of the arch. There are four canines. These teeth are thick and like an ice pick come to a point tearing and ripping foods that may be tough.


Adjacent to the canines in the permanent dentition are two premolars (also called bicuspids) for a total of eight teeth. These teeth are a cross between canines and molars in that they have two broad points for tearing but also present with a broader chewing surface for chewing and grinding. Upper first premolars typically present with two roots and the second with one root. Lower premolars typically present with one root.


Adjacent to the premolars are three molars for a total of twelve. The first molar also called the six year molar presents at six years of age. The second molar also called the twelve year molar presents at approximately twelve years of age. Finally the third molar also called the wisdom tooth are the last teeth in the mouth and present if there is enough room between eighteen to twenty-one years of age. These multi-rooted teeth with broad chewing surfaces are ideal for crushing, grinding and chewing foods.

Tooth Numbering

The International Numbering System is a standardized approach for referencing particular teeth. In this system teeth that should be present are numbered according to location and sequence. The first number corresponds to the quadrant location with 1 representing the upper right, 2 the upper left, 3 representing the lower left and 4 representing the lower right. The second number represents the sequence of the teeth from front to back. Thus, 1 is the front central incisor, 2 the lateral incisor, 3 the canine, 4 the first premolar, 5 the second premolar, 6 the first molar, 7 the second molar and 8 the third molar. As an example tooth number 33 is the lower left canine and tooth number 15 is the upper right second premolar.
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