Tooth Numbering

SystemDr. Amitha G

Dept of Oral Pathology

The Primary (Deciduous) Teeth◦The postnatal period of development is about 2½ years

◦Remains intact until a child is about 6 years of age when the transition to the permanent dentition begins.

◦The number of primary teeth present in the child is usually 20(unless congenitally missing or lost due to disease)

Dental formula for the primary teeth in humans is: I 2 C 11 M 2 = 10 2 1 2

Nomenclature for Deciduous Teeth◦The “Universal System notation for the entire primary dentition is,

A B C D E

F G H I J

T S R Q P

O N M L K

◦ Another notation system divides the arches into quadrants with the entire dentition notated as,

E D C B A A B C D E

E D C B A

A B C D E

The Permanent Teeth◦ The number of teeth in adults, including

third molars when present is 32Transition to permanent dentition begins:◦ with the eruption and emergence of the first

permanent molars, ◦ shedding of the deciduous incisors and ◦ emergence and eruption of the permanent

incisors

◦After shedding of the deciduous canines and molars, emergence and eruption of the permanent canines and premolars, and emergence and eruption of the second permanent molars.◦This process requires about 20 years to complete

Nomenclature for Permanent Teeth◦ The permanent dental formula is: I 2 C 1 P2 M 3 = 16 2 1 2 3◦Universal notation system ◦ Palmer Notation system

Nomenclature for permanent teeth

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

Thus, the right maxillary first molar is designated as 3, the maxillary left central incisor as 9, and the mandibular right first molar as 30

Universal System the maxillary teeth are numbered from 1 through 16, beginning with the right third molar. Beginning with the mandibular left third molar,the teeth are numbered 17 to 32.

8 7 6 5 4 3 2 18 7 6 5 4 3 2 1 1 2 3 4 5 6 7 81 2 3 4 5 6 7 8

8 7 6 5 4 3 2 18 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

◦Another notation system (Palmer Notation) uses the quadrant system, in which beginning with the central incisors, the teeth are numbered 1 through 8 (or more).

◦ Two digit system or FDI system(by Federation Dentaire Internationale)

◦ For both the primary and permanent dentitions has been adopted by WHO and accepted by other organizations such as the International Association for Dental Research .

◦Primary Teeth

55 54 53 52 51 61 62 63 64 65 85 84 83 82 81 71 72 73 74 75

Permanent Teeth

First digit indicates the quadrant Permanent dentition ( 1 to 4) Primary dentition ( 5 to 8)

Second digit indicates the tooth within the quadrant Primary dentition (1 to 5) Permanent dentition (1 to 8)

18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 2848 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38

The Crown and the Root◦The crown is covered with enamel◦Root is covered with cementum◦Join at the cemento enamel junction(cervical line)◦With pulp chamber and pulp canals

The four tooth tissues◦ Enamel◦ Cementum ◦Dentin◦ pulp

The root portion

◦Maybe single with one apex or terminal end

Found in anterior teeth and some of the premolars◦Or Multiple with a bifurcation or trifurcation dividing the root portion into two or more extensions or roots with their apices or terminal ends found in all molars and premolars.

The root portion of the tooth is firmly fixed in the bony process of the jaw, so that each tooth is held in its position relative to the others in the dental arch

The alveolar process is the portion of the jaw which serves as a support for the tooth

The crown portion◦ is partly covered at the

cervical third in young adults by soft tissue of the mouth known as the gingiva or gingival tissue.

Surfaces and ridges

◦Crowns of the incisors and canines have four surfaces and a ridge

◦Crowns of the premolars and molars have five surfaces

◦Surfaces are named according to their positions and uses

◦

Labial,buccal (facial surfaces)lingual ,proximal (mesial/distal) incisal occlusal

Contact area- the area of the mesial or distal surface of the tooth which touches its neighbor in the arch

Other Landmark◦ Cusp- is an elevation or

mound on the crown portion of a tooth making up a divisional part of the occlusal surface

Cingulum◦ - is the lingual lobe of an

anterior tooth. It make up the bulk of the cervical third of the lingual surface.

Tubercle◦ is a smaller elevation on

some portion of the crown produced by an extra formation of enamel

Ridge◦ is any linear elevation on

the surface of the tooth and is named according to its location (buccal ridge, incisal ridge, marginal ridge)

Marginal ridge◦ are those rounded borders

of the enamel that form the mesial and distal margin of the occlusal surfaces of premolars and molars and the mesial and distal margins of the lingual surfaces of the incisors and canines.

10. Distal Marginal Ridge10. Distal Marginal Ridge 11.11.Mesial Marginal RidgeMesial Marginal Ridge

Oblique ridge-

◦is a ridge crossing obliquely the occlusal surfaces of maxillary molars.

15. Oblique Ridge

Transverse ridge

◦A transverse ridge is the union of a buccal and lingual triangular ridge that crosses the surface of a posterior tooth transversely (roughly 90 degrees to both the buccal and lingual tooth surfaces).

Fossa- is an irregular depression or concavity

Lingual fossae are on the surface of incisors

Centrasl fossae are on the occlusal surface of molars

Triangular fossae- are found on molars and premolars on the occlusal surfaces mesial or distal to marginal ridges

11. Mesial Triangular Fossa12. Distal Triangular Fossa

13. Central Fossa

Sulcus◦ is a long depression or

valley in the surface of a tooth between ridges and cusps the inclines of which meet at an angle.

Developmental groove◦ is a shallow groove or line

between the primary parts of the crown or root.

◦

Supplemental grooves- less distinct, is also a shallow linear depression on the surface of the tooth, but it is supplemental to a developmental groove and does not mark on the buccal and lingual surfaces of posterior teeth.

Pits◦ are small pinpoint

depression located at the junction of the developmental grooves or at terminals of those grooves.

Central pit-Central pit- use to describe a use to describe a landmark at the central landmark at the central fossa of molars where fossa of molars where developmental grooves joindevelopmental grooves join

Lobe

◦ is one of the primary section of formation in the development of the crown.

◦Lobe- is one of the primary section of formation in the development of the crown.

◦Mamelons is any one of the three rounded protuberances found on the incisal ridges of newly erupted incisor teeth

For purposes of description

◦ the crowns and roots of

teeth have been divided into thirds and junctions of the crown surfaces are described as line angle and point angle

Line angle◦ is formed by the junction of two surfaces and derives its name

from the combination of the two surfaces that joinLine angles of anterior teeth are:Mesiolabial distolingualDistolabial labioincisalMesiolingual linguoincisal

The line angles of the posterior teeth mesiobuccal distolingual bucco-occlusal distobuccal mesio-occlusal linguo-occlusal mesiolingual disto-occlusal

Point angles◦ is formed by the junction of the three surfaces◦ Ex. The junction of the mesial,buccal, and occlusal surfaces of

a molar is called the mesiobucco-occlusal point angle.

◦ Point angles of the anterior teeth are: mesiolabioincisal mesiolinguoincisal distolabioincisal distolinguoincisal◦ The point angles of the posterior teeth are: mesiobucco-occlusal mesiolinguo-occlusal distobucco-occlusal distolinguo-occlusal

THANKYOUReference:Wheelers – Dental Anotomy, Physiology and Occlusion- 9th edition.