7/29/2019 When Does Primary Dentition Last Until
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When does primary dentition last until?
Primary dentition exists
until beginning of mixed
dentition with the
emergence (eruption) of the
permanent first molars at
age six, which erupt distal
to the primary secondmolars. Thus the permanent
molars have no primary
predecessors.
1. How do
primary teeth
compare in
size?
2. How do
they compare
in color?
3. Describe
the cervical
ridges ofprimary
teeth. How
do they
appear at the
cervix?
4. How are
the roots in
relation to
adult teeth?
Primary teeth are smaller
in overall dimensions but
bear resemblance to
permanent teeth except the
primary Mandibular first
molar which is the most
unique primary tooth
morphologically
Primary teeth are lighter
in color Primary teeth have more
pronounced cervical ridges
(i.e. cervical 1/3 B & L
height of contour)
Primary teeth appear more
constricted at the cervix
(neck)
Primary roots are long and
narrow in relation to crown
width and length
1. How do the pulp horns
compare?
2. Describe the shape of theroots of primary teeth?
What do the trunk roots look
like?
3. Describe the buccal and
lingual surfaces of primary
molars
Primary teeth have large pulps with long pulp horns (esp.
molars)
Primary molars have more flared and slender roots which extend
beyond thecrown outlines, thus allowing space for the growth and
development of the
succeeding permanent teeth (i.e. premolars)
Primary molars have short root trunks with furcation areas
approaching the CEJ
Primary molars have buccal and lingual surfaces that are more
convergent
occlusally which results in a narrower occlusal table
1. How does the enamel of
primary teeth compare to adult
teeth?
2. How much dentin do
primary teeth have compared
to adult teeth?
3. How does the shape of theroot compare to the crown?
Primary teeth have thin enamel with consistent thickness; enamel
rods of
primary molars at the CEJ point occlusally rather than
gingivally as with
permanent molars
Primary teeth have little dentin between pulp and dentino-enamel
junction
(DEJ) (clinically significant)
Primary anterior teeth have comparatively longer and narrower
roots with
respect to their crowns (which appear wider mesiodistally and
shorterocclusocervically than the permanent anterior teeth)
What is missing from the
incisal ridge of primary
anterior teeth?No mamelons!
7/29/2019 When Does Primary Dentition Last Until
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1. What is Leeway Space?
How is this relevant to
primary and permanent
molars?
Primary molars are wider mesiodistally than the premolars that
replace them (the
difference between the two dimensions is called the Leeway Space
which allows
space for some mesial movement of the permanent first molars as
the premolars
erupt)
Asjawsgrow,spacingbetweenprimary anteriors occurs thus providing
room for the
larger permanent successors to eruptPrimary teeth sequence..
Mand. Central
Mand. Lateral
Max.Central
Max. Lateral
Mand. M1
Max.M1
Mand. Canine
Max.Canine
Mand. M2
Max.M2
1. Mand central: 6 mos
2. mand lateral: 7 mos
3. Max central: 7+ mos
4. Max lateral 8 mos
5. Mand M1: 12 mos
6. Max M1: 12+ mos
7. Mand canine: 16 mos
8. Mas canine: 16+ mos
9. Mand M2 20 mos
10. Max M2 20+ mos
Primary anterior teeth: incisors
1. Do they have mamelons?
2. Where are the heights of contour?
3. Describe the mesial and distal CEJ in relation
to one another.
4. What are the roots like?
5. What is the DI angle shape?
Incisors very similar in form to permanent counterparts,
but smaller
no mamelons
crown form appears squatted
marked buccal and lingual cervical ridges (bulges) i.e.
heights of contour
mesial CEJ more incisally positioned than distal as in all
teeth
roots more narrow and pointed DI angle of lower lateral
incisor quite rounded
Primary canines
1. What is the shape of the
crown?
2. Describe the mesial cusp and
distal ridge?
3. Where are the cervical bulges
more prominent, max or mand?
4. Which canines, max or mand,
have less prominent marginal
ridges? What aspect is this on?
Canines maxillary canine has diamond-shaped crown (facial
view)
maxillary canine has longer mesial cusp ridge (slope) than
distal slope
(opposite of permanent max. canine) maxillary canine has marked
facial and lingual cervical bulges
mandibular canine has arrow-shaped crown (facial view)
mandibular
canine has shorter mesial slope than distal
slope
mandibular canine more slender with less prominent marginal
ridges on
lingual aspect
Max 1st molar - primary
1. What tooth does it resemble?
Which cusp is the largest?
2. In what dimension is the
crown wider?
3. Where are the heights of
contour?
4. How many roots and what is
their shape?
1st Molar basically resembles maxillary premolar (two major
cusps: MB
and ML are largest; DB and DL insignificant in size; smallest DL
cusp not
always present; largest cusp is MB
crown wider mesiodistally than occlusocervically
prominent B & L cervical heights of contour (bulges) esp.
B
Threerootslikemaxillarymolarbutmore slender and flared
Very small root trunk
Max 2nd molar - primary
1. What tooth is this
identical to?
How is it slightly different
from this tooth?
2nd Molar morphologically identical to permanent maxillary 1st
molar including
cusp of Carabelli; smaller and squatter than permanent maxillary
1st molar; roots
more flared and slender
very small root trunk
larger than primary 1st molar; greatest faciolingual diameter of
all primary teeth
