difference between primary and permanent teeth

DIFFERENCE BETWEEN

PRIMARY AND PERMANENT DENTITION

Dr. J. Jude

NUMBER

Primary A total of 20 teeth 10 in each jaw and 5 in each quadrant.

Permanent A total of 32 teeth 16 in each jaw and 8 in each quadrant

DENTAL FORMULA

Primary  I 2/2 ,C 1/1 ,M 2/2

Permanent I 2/2 ,C 1/1 ,PM 2/2 ,M 3/3

ERUPTION SEQUENCE Primary A B C D E / A B D C E

Permanent Maxillary Teeth: 6124357 Mandibular Teeth: 6123457

DURATION OF DENTITIONPrimary Lasts from 6months to 6 years

Permanent 12 years and beyond

SIZEPrimary smaller in over all size and crown dimensions

Permanent larger

COLORPrimary lighter. Their refractive index is comparable to

that of milk.

Permanent darker. They appear yellowish white

SHAPE ( ANTERIOR TEETH )

Primary Mesiodistal length is more than the cervicoincisal

length.

Permanent Cervicoincisal length is greater  

CERVICAL CONSTRICTIONPrimary More prominent

Permanent Less prominent 

CERVICAL RIDGEPrimary More prominent

Permanent Less prominent

MAMELONS Primary do not exhibit mamelons

Permanent Newly erupted permanent incisors exhibit

mamelons. 

CANINES Primary More conical in shape and the cusp tip is more

pointed and sharp.

Permanent Less conical and cusp tips are less pointed. 

 OCCLUSAL PLANEPrimary relatively flat

Permanent curved contour.

GROOVESPrimary Supplemental grooves are more

Permanent Supplemental grooves are less

CONTACT AREASPrimary broader, flatter and situated gingivally

Permanent narrower and situated occlusally

 MOLARSPrimary Crown of second molar is larger than the first

molar.

Permanent Crown of first molar are larger than the second

and third molar. 

UPPER 1ST MOLARPrimary Has 3 cusps

Permanent Has 4 cusps + 1 accessory cusp.

UPPER 2ND MOLARPrimary 4 cusps + 1 accessory cusp

Permanent Has 4 cusps

LOWER 1ST MOLARPrimary 4 cusps

Permanent Has 5 cusps

LOWER 2ND MOLARPrimary 5 cusps

Permanent Has 4 cusps

ROOTPrimary narrow and straight

Permanent longer and curved

ROOT TRUNKPrimary Furcation of molar roots is placed more cervically

so that the root trunk is much smaller

Permanent Furcation in molars is placed more apically and

thus trunk is larger.

RESORPTIONPrimary undergo physiologic resorption and the primary

teeth are shed naturally

Permanent Physiologic resorption is absent

PULP CHAMBERPrimary proportionately larger when compared to crown

size

Permanent smaller in relation to crown size  

PULPAL OUTLINEPrimary follows DEJ more closely

Permanent follows DEJ less closely

PULP HORNSPrimary higher and closer to outer surface

Permanent lower and away from outer surface

ROOT CANALSPrimary thin, tortuous and branching path

Permanent well defined and less branching

ACCESSORY CANALSPrimary Floor of the pulp chamber is more porous

Permanent Floor of the pulp chamber do not have many

accessory canals.

APICAL FORAMENPrimary wider

Permanent smaller/Narrower

ENAMEL THICKNESSPrimary Enamel is thinner and is about 1mm of uniform thickness

Permanent Enamel is 2-3 mm thick and is not uniform in thickness.

DIRECTION OF RODSPrimary Enamel rods at the cervical third of primary

crowns are directed occlusally

Permanent Enamel rods at the cervix are directed

apically.

DENTIN THICKNESSPrimary half that of permanent teeth.

Permanent Greater thickness of dentin

DENTINAL TUBULESPrimary less regular.

Permanent more regular.

INTERGLOBULAR DENTINPrimary Absent

Permanent present

BLOOD SUPPLYPrimary primary teeth have abundant blood supply,

poor localization of infection and inflammation.

Permanent reduced blood supply. Thus, infection and

inflammation are comparatively well localized 

NERVE SUPPLYPrimary less densely innervated.

Permanent more densely innervated

CEMENTUMPrimary Cementum is thin, made up of only primary

cementum

Permanent Cementum is thick, both primary and secondary

cementum are present.

MINERAL CONTENTPrimary Both enamel and dentin are less mineralized and

less dense

Permanent Both enamel and dentin are more mineralized

and more dense.

NEONATAL LINEPrimary Neonatal lines are present in all primary

teeth both in enamel and dentin

Permanent Neonatal lines are seen only in first molar.