Dental Anatomy - Primary Dentition

primary dentition are also known as

deciduous dentition

Universal Notation

- alphabetic

- A-J (starting at maxillary right)

- K-T (starting at mandibular left)

- E and F, O and P are central incisors

there are __ teeth in primary/deciduous dentition

20

Palmer Notation

- A: central incisor

- B: lateral incisor

- C: canine

- D: first molar

- E: second molar

- bracket indicates quadrant

- maxillary right canine is upper right bracket and C

FDI Classification

First number (quadrant)

5- maxillary right

6- maxillary left

7- mandibular left

8- mandibular right

Second number (tooth)

1- central incisor

2- lateral incisor

3- canine

4- first molar

5- second molar

Dental Formula

- number and letter designation of the various types of teeth

- indicates dentition on only 1 side of the mouth but does include upper and lower quadrants so you multiply by 2 for the entire dentition

Dental Formula Example

- number pattern for primary and permanent human teeth

- I - incisor, C - canines P - premolars and M - molars

- Permanent Dentition (2 on top, 2 on bottom, etc)

I: 2/2 C: 1/1 P: 2/2 M: 3/3

- Primary Dentition

i: 2/2 c: 1/1 m: 2/2

Characteristics of Primary Teeth

- smaller in overall dimension than permanent teeth

- roots are longer and more slender than their crowns

- narrow cervical root necks on anterior teeth

- cervical ridge on anterior (La and Li) and posterior (Buccal)

- short and narrow root trunks on posteriors

- posterior roots flare considerably

- minimal or no root trunk

- more opaque and whiter than permanent teeth

the purpose of root flare on posteriors is to

creates additional space for the permanent premolar crown to develop

Characteristics cont

- pulp chamber proportionately larger than permanent tooth chambers

- pulp horns are higher and closer to the enamel than in permanent teeth

- root canals are narrower and finer than permanent teeth

- thin enamel and dentin (can cause cavities to occur quicker)

Eruption schedule

Central Incisors: 6 mo (Mand) 7.5 mo (Max)

Lateral Incisors: 7 mo (Mand), 9 mo (Max)

Canines: 16 mo (Mand), 19 mo (Max)

First Molars: 12 mo (Mand), 14 mo (Max)

Second Molars: 20 mo (Mand), 24 mo (Max)

Replacement of Deciduous Teeth

- permanent teeth positioned lingual or beneath predecessors

- resorption (osteoclastic activity) melts deciduous roots away for around a year or longer

- exfoliation (detachment) of deciduous crown

Active Eruption

- movement through mucous membrane of alveolar process

- completed when tooth contacts opposing dentition

Passive Eruption

continuous process of adaptation to changing conditions like tooth wear or loss

Primary Dentition Period

- when you only have deciduous teeth

- 6 mo to 6 years of age

Mixed Dentition Period

- deciduous and permanent teeth present

- 6 years to 12 years of age

Maxillary Central Incisors

- greater mesiodistal than cervicoincisal length

- no mamelons or grooves

- nearly straight incisal edge

- prominent labial and lingual cervical ridges

Maxillary Central Incisors roots

- twice the length of the crown

- tapers toward apex

- round cross section

Maxillary Lateral Incisors

- similar crown to centrals but smaller in all dimensions

- greater cervicoincisal length compared with mesiodistal width

- deeper lingual fossa and more pronounced marginal ridges than central incisors

Maxillary Lateral Incisors roots

appear much longer in proportion to the crown compared to centrals

Mandibular Central Incisors

- straight incisal margin

- no mamelons

- M and D sides taper evenly

- marginal ridges less pronounced than primary max incisors

- wide labiolingual dimension

Mandibular Central Incisors roots

- 2-3x the crown height in length

- taper to pointed apex

- narrow and conical (cone shaped)

Mandibular Lateral Incisors

- wider, longer, more developed cingulum than centrals

- sloped incisal margin

- labiolingual dimension is equal to central incisors

- cingulum offset to the distal

Mandibular Lateral Incisors roots

- distal longitudinal groove

- distal curvature

Maxillary Canines

- bulkier than primary incisor crowns in every aspect

- more cervically restricted in regard to mesiodistal width

- more convex on mesial and distal surfaces

- longer mesioincisal ridge

- well developed facial lobes with a sharp cusp

- ML and DL fossa

Maxillary Canines roots

- twice as long as the crowns

- more slender than perm max canines

Mandibular Canines

- narrower labiolingually than maxillary canines

- similar incisocervical length

- longer distoincisal cusp ridge

- less prominent lingual features than maxillary canines

Mandibular Canines roots

- long, narrow, almost twice the crown length

- shorter and more tapered than maxillary canine roots

Maxillary First Molars

- different from other primary or permanent teeth

- wider buccolingually than mesiodistally

- two major cusps (MB and ML)

- distolingual cusp may be present (small and rounded)

- cervical line offset toward mesial

- transverse and oblique ridges

- central, mesial, distal triangular fossae

- prominent cervical ridge on buccal surface

- disto-occlusal groove

Maxillary First Molars roots

- 3 roots, lingual largest

- flare to accommodate developing permanent premolar

- very short root trunk

- roots are long, slender, widely divergent

Maxillary Second Molars

- shape similar to maxillary first permanent molar

- smaller than permanent maxillary first molars but larger than primary maxillary first molars

- 4 major cusps and 5th minor Cusp of Carabelli

- cervically narrow

Maxillary Second Molars roots

- shorter root trunk than perm max molar

- longer roots than primary first molar

- 3 widely flared roots (lingual longest, distobuccal shortest)

Mandibular First Molars

- crowns unlike any other primary or permanent tooth

- wider MD than BL

- 2 buccal cusps (M larger than D)

- 2 lingual cusps (M larger than D)

- bulbous curvature on buccal surface in cervical 3rd with narrow occlusal table

- central and mesial pits

- transverse ridge

Mandibular First Molars roots

- 2 roots (M and D)

- mesial root is flat and broad with two root canals

- distal root has one root canal and is thinner and shorter

- apex is very blunt and almost flat

Mandibular Second Molars

- crown like permanent mandibular first molars but smaller

- less pentagonal shape

- MB, DB, D cusps more equal in size

- narrow BL dimension

Mandibular Second Molars roots

- twice as long as the crowns

- slender, long, widely flaring

- M root longer than D