The document describes the anatomy and morphology of the maxillary first premolar tooth. Key points include: - It has two cusps (bicuspid) and usually two roots (buccal and lingual) - Eruption occurs between 10-12 years of age - The crown is trapezoidal in shape with prominent buccal and lingual ridges

1. DR MONIKA
MDS ORAL PATHOLOGY ,MICROBIOLOGY AND FORENSIC
ODONTOLOGY

3.  Premolars are so named because
they are placed between the anterior
teeth and the molars (pre = before)
 Premolars assist canines & molars
in tearing and chewing food
 Have two cusps (bicuspid) & two
roots (buccal & lingual)
 Eruption : at 10-11 years

4.  TOOTH NUMBERING
 Universal : #5 , #12
 Z-P : 4 4
 FDI : 14, 24

5.  First evidence of calcification :1.5 – 1.75 yrs
 Enamel Completion : 5-6 yrs
 Eruption : 10-11 yrs
 Root completion : 12-13 yrs

7.  Crown : Pentagonal shaped or
roughly trapezoidal .
 Crown closely resembles to
maxillary canine and second
premolar
 Crest of curvature of the cervical
line bucally is near the center of
the root .

8.  Contour of the mesial outline
is concave from the contact area
to the cervical line
 The mesial slope of the buccal
cusp is longer than distal slope,
which is the opposite of canine
 Disto-occlusal angle is a little
less prominent and the cervical
concavity is not as deep

9.  Tip of buccal cusp is distal to a line
bisecting the buccal surface of the
crown .
 Mesial slope of the buccal cusp is
sometimes notched .
 Distal outline of the crown below
cervical line is starighter than that of
mesial somewhat may be concave
 Distal contact area is broader .
 The contact areas are somewhat at
same level .
 Buccal cusp is long and pointed .

10.  Occlusal margin of this tooth
is, similar to the incisal margin
of the maxillary canine
 Buccal ridge
 Mesio-buccal & distobuccal
developmental depressions on
each side of buccal ridge

11.  • The crown tapers
towards the lingual
aspect
 • The lingual cusp is
shorter than the buccal
cusp
 • The lingual cusp is
smooth from the cervical
portion to the area near
the cusp tip

12.  The cusp tip is pointed with
mesial and distal slope
meeting at an angle of about
90 degrees
 • Small portion of the
buccal cusp can be seen
from this aspect
 Smoothly convex in all
directions
 There is no clearly
defined lingual ridge

13.  Mesial and distal outlines
are normally somewhat
convex & shorter than the
same outlines of the buccal
surface
 Lingual cusp tip is not as
sharply pointed as the buccal
cusp tip
 The mesio-occlusal slope is
shorter than the disto-
occlusal slope

14.  • From the mesial and distal
aspect both the buccal and lingual
cusps are visible
 • A well developed mesial
marginal ridge and a mesial
marginal developmental groove is
present
 • In the middle of the mesial
surface is the mesial
developmental depression which
continues beyond the cervical line

15.  Shape of the mesial surface is
trapezoidal
 Buccal outline is generally
convex, with the height of contour
in the cervical third
 Lingually the outline takes the
form of an even arc, with the
height of contour in the middle
third

16.  Occlusal margin is irregularly
concave and the majority of it is
made up of the mesial marginal
ridge.
 A prominent mesial marginal
groove is usually present
indenting the occlusal margin
almost two-thirds of the way from
the buccal to the lingual outline.

17.  There is no developmental
depression or groove on this aspect,
instead it is convex at almost all
points
 The curvature of the cervical is less
on this aspect
 The contact area is near the
junction of occlusal and middle third
distal is remarkably similar to the
mesial surface, although it is slightly
shorter occluso-cervically.

18.  Lingual margin is almost
symmetrical & is quite
convex, especially in middle
third, where height of
contour is located
 Occlusally, distal is similar
to mesial aspect, except that
marginal ridge is located at a
more cervical level
 There is normally no
marginal groove

19.  • Within cusp ridges and marginal
ridges the following are present
 TBC & TLC : Tip of Buccal &
Lingual cusp
 BTR & LTR : Buccal & Lingual
Triangular ridge
 DBDG: disto-buccal
developmental groove
 DTF & MTF : Mesial & Distal
triangular fossa CG : Central
groove

20.  outline of crown can be
described as hexagonal or six-
sided and it is wider
buccolingually than
mesiodistally
 prominent buccal ridge is
primary contributor to generally
convex buccal outline
 lingual margin is evenly
convex, almost in a semicircle
 Proximal margins are relatively
straight & they converge toward
lingual

21.  • Most Maxillary first premolars
have 2 roots, but one and three roots
can also be seen
 • Two roots : buccal and lingual
 • Buccal portion of the root
resembles canine

22.  • The root when viewed from the
proximal side shows a big trunk
and bifurcation area from where
the buccal and lingual root
separate
 • A developmental depression is
seen on the mesial aspect of the
trunk TRUNK

24.  First evidence of calcification.. 2- 2 1/2
years.
 Enamel completed.. 6-7 years.
 Eruption.. 10-12 years.
 Root completion.. 12-14 years.

25.  I. Geometric outline Trapezoidal.
 II. Outline
 a. Mesial - Slightly convex.
 b. Distal -More convex.
 c. Cusp - Short, less pointed and
 Mesial slope is shorter than
Distal slope
 Tip is displaced to the MESIAL.

26.  III. Contact areas:
 a. MESIAL - at the junction
between middle and
occlusal 3rd
 b. Distal at middle of
middle 1/3 rd
 IV. Surface anatomy :
 Buccal and cervical ridges.
 V. Cervical line: convex root
wise.
 VI. Root: single tapering
from cervical to apical with a
Distal curved apex.

27.  Lingual convergence.
 Reversed outlines.
 Lingual cusp is sharp,
lingual cusp is longer ,making
crown longer on the lingual
side or same length as buccal
cusp.

28.  I. Geometric outline- Trapezoidal.
 I. Outlines
 a. Buccal and lingual - Slightly convex.
 b. Cusps.. Almost same length; greater
distance between cusps which widen
the occlusal Surface.

29.  III. Crest of curtvature:
 Buccal :at junction between middle and
cervical 3rd
 Lingual :middle of the middle 3rd
 IV. Surface anatomy :
 Aspect is smooth and convex with NO
depressions.
 Mesial marginal ridge is more occlusion
than Distal one.
 Contact area is broad.
 V. Cervical line: concave root wise.
 VI. Root: single; broad buccolingual with
relatively blunt apex
 . Shallow developmental depression.

30.  Similar to the Mesial aspect.
 Distal contact area is wider and more
cervical.
 Distal marginal ridge is more cervical.
 Straighter cervical lines.
 Deeper developmental depression.

31.  Geometric outline: oval or
rounded.
 Elevations:
 a. Cusps- Both at the same size
with wide distance in between.
 b. Marginal ridges.. thick, strong
and well developed

32.  Depressions:
 a. Central groove.. Short with
multiple supplemental grooves.
 b. Triangular fossae: near to each
other;
 Distal is larger and deeper than
Mesial .