Transcript PERMANENT MANDIBULAR MOLARS

PERMANENT MANDIBULAR
MOLARS
MANDIBULAR
st
1
• the largest and the strongest
mandibular molars
• not considered succedaneous
• first permanent molars to
erupt=six year molars
• 5 cusps
• 2 roots D &M (3 canals: 1-D,
2-M)
MOLAR
UNIQUE FUTURES
• largest mesiodistal crown dimension of any
tooth
• he occlusocervical and faciolingual
dimensions of the first molar are greater than
any other mandibular molar
• Mandibular first molars have three facial
cusps as do some mandibular third molars
• the longest roots of any molar
• the greatest mesiodistal root separation of
any molar
• The mesial root has the greatest faciolingual
dimension of any root in the mouth
Buccal view
• The mesiofacial (mesiobuccal)
cusp is the largest, widest, and
highest of the 3 facial cusps
• The facial (buccal) cervical
line is nearly straight but there
can be enamel that dips
cervically nearly into the
furcation
• The two lingual cusps
(mesiolingual and distolingual)
are visible because they are
taller cusps
• The mesial root
averaged 1 mm longer
than the distal root
• Both roots have an
overall distal inclination
• The distal root is
straighter than the
mesial root
Lingual view
• The greater height of the
lingual cusps hide the
facial cusps
• portions of the proximal
surfaces are visible from a
lingual view
• The lingual cervical line is
nearly straight
Mesial view
• Two cusps can be seen (ML & MB)
• Only one root can be seen (FL length
twice MD)
• The mesial cervical line curves
occlusally
• The lingual height of contour (area of
greatest convexity) has been located
in the middle third of the crown
• The faciolingual (buccolingual)
crown, root, cusps dimension is
greater M than D
• The two major mesial cusps
(mesiofacial and mesiolingual) are
larger than the distal cusps
Distal view
• Distolingual cusp is largest
• distal proximal contact has been
located facial to the crown center
(Fuller/Denehy/Schulein; Renner),
centered over the root
• From a distal view, more of the facial
surface can be seen than from a mesial
view because the crown tapers distally
• More of the occlusal surface is visible
from a distal view than mesial view
because the distal surface is shorter
occlusocervically
Occlusal view
• 5 cusps. All of them functional
• The mesiofacial cusp is the
largest cusp
• The crown tapers lingually
• The outline form has been
described as pentagonal
• There are four developmental grooves
on the occlusal surface: central;
mesiofacial (mesiobuccal); distofacial
(distobuccal); and lingual
• There are three fossae: central;
mesial; and distal
• The central developmental groove has
a zigzag mesiodistal form
• The central development groove
forms a “Y” shape with the lingual
developmental groove. This is one of
the principal occlusal groove patterns
MANDIBULAR
• Resemble 1st B and L
except there no 5th cusp
or D cusp
• Rooth shorter, closer
more D inclined
• 4 cusp nearly equal size
nd
2
MOLAR
UNIQUE FUTURES
• F the roots curve laterally and then
toward each other in a manner that
resembles the handles of a pair of
pliers a unique form shared with
only the maxillary first molar
• a MF prominence, a unique feature
for mandibular molars
• The D proximal contact is centered
both FL and occlusocervically, a
characteristic shared with four other
teeth (Max lateral incisor, Max
canine, Max 1st molar and Max 2nd
molar)
Facial view
• Shorter MD and
cervicoolcclusally than 1st
• Just 2 B cusps
• Roots shorter, closer, more
D inclined
Lingual view
• Little if any of the mesial and distal
surfaces are visible lingually due to
the limited lingual crown taper
• The lingual groove may terminate
on the occlusal surface or extend
onto the lingual surface in the
occlusal third (L pit)
• Contact areas lower D and M
Mesial view
• The FL dimension of the M root is
greater than the distal , but less
rhan 1st molar
• mesial proximal contact - similar to
the 1st molar, slightly to the facial
of the center of the crown
• The cervical line is more cervically
positioned on the facial surface
than lingual
Distal view
• No Distal cusp
• Little of the facial surface is
visible from a distal view
• proximal contact has been
located at the center of the
crown
• Distal root is narrower than M
Occlusal view
• The outline form has been described as
rectangular
• A number of supplemental grooves are
present, “wrinkled” appearance
• mesiobuccal cusp is normally the
largest cusp, but almost equal in size
• developmental grooves: facial; central;
and lingual, forming a cross
• 3 fossae, 3 B, L & M pits+grooves may
present
MANDIBULAR
RD
3
• more varied in size and shape than all
other teeth except the maxillary third
molars
• small apical-occlusal dimension
• the D half of the crown has a noticeably
shorter than the M half
• crown resembles a mandibular second
molar with 4 cusps
• Some mandibular third molars have three
facial cusps
• The mesiolingual cusp is the largest of all
the cusps. The lingual cusps are often
larger and longer than the facial cusps and
more rounded
MOLAR
•
•
•
•
•
•
The roots are usually pointed,
inclined D, often fused, short
There may be multiple roots and as
many as 8 roots
The facial surface is very convex
and the tooth has a bulbous form
occlusal outline form is often ovoid
The occlusal table is distinctly ovoid
in outline form and highly restricted
The occlusal surface is quite
“wrinkled” due to numerous
supplemental grooves and ridges
MANDIBULAR MOLAR
ROOTS
• 2 roots: 1-M, 2 – D with
single root trunk
• M root – longer and
stronger, curves M then
turns D near apex
• Root trunk short and
grooved on B and L
surfaces
CHARCTERISTICS
PULP CAVITY