difference between primary and permanent teeth
TRANSCRIPT
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.