Everything related to Upper First Pre-Molar is explained. From the functions, chronology and aspects of the tooth completely anatomically. In addition to the shape of the pulp and its structural anatomy

1. Upper First Pre-Molar
By:
Dr: Omar Abdelsalam

2. Functions
1
Mastication
of food
2
Maintain the
vertical
Dimension of
The face
3
Supporting
the corners
Of the mouth
and cheeks
To keep them
from sagging
4
First pre-
molar assist
the Canine in
shearing or
cutting food
particles

3. Chronology
First
Evidence of
Calcification
1.5-1.75
years
Enamel
Completed
5-6 years
Eruption
10-11 years
Root
completed
12-13 years

4. 5
Aspects
Buccal
Lingual
Mesial
Distal
Incisal

5. 1- Buccal Aspect
• Trapezoidal
• M. outline : slightly concave
• D. outline : less concave
• Contacts areas are broad (‫)عريض‬
1. M.C.A & D.C.A : at junction of occlusal
and middle thirds
• Buccal cusp : long & mesial slope is
straight & longer than distal slope &
curved
• Tip is distally to a line bisecting (‫)ينصف‬ the
crown buccally
• Cervical line : slightly convex root wise
Surface
• Convex
• ELEVATIONS :
1. Cervical ridge
2. Buccal ridge
• DEPRESSION :
1. 2 developmental depression
2. 3 lobes middle most developed
3. M.B. & D.B lobes
Root
• Most of them have 2 roots B.LI.
• 2 pulp canals .
• Usually one root with 2 canals .
• Resembles that of the canine only
3,4mm shorter .

6. 2- Lingual aspect
• Li. Cusp : shorter than buccal by 1mm
• Narrower mesiodistally
• Cusp tip : pointed
• M. & D. slopes : meeting at right angle
• Cervical line : regular & less convex root wise than buccal
• Lingual ridge : crest of the lingual convexity which terminate at lingual cusp tip
Surface
• Mesial and distal outline : straight near
convex then convex and continues with
slopes of lingual cusp .
• Surface of crown : convex
Cusp is smooth and convex at all points .
Root
• Lingual portion of root : 2 roots are
present are smooth and convex
• Apex of lingual root : blunter than that of
buccal root

7. 3- Mesial Aspect
• Trapezoidal
• B. outline : convex
• B. crest of curvature : cervical third
• Cusp tip : on line with apex buccally
• Li. Outline : convex
• Li. crest of curvature : near center of the middle third
• Tip : online with lingual apex root
• Li. Cusp : shorter than buccal by 1mm
• M.M.R. at the junction of occlusal and middle thirds
• Cervical line : concave root wise , depth : 1mm
• Mesial developmental depression immediately cervical to the mesial contact area , it runs
beyond cervical line to join a deep developmental depression at bifurcation (‫)التفرع‬ .

8. 4-distal aspect
• Crown : convex (except) small flatted areas :-
1. Cervical to contact area .
2. Buccal to the center of distal surface
• No deep developmental groove crossing the D.M.R.
• Cervical line : less convex ( straight )
• Root trunk : no developmental depression , no developmental grooves
• BIFURCATION is near apical third

9. 5- occlusal aspect
• Hexagonal (‫)سداسي‬ , not equilateral (‫االضالع‬ ‫متساوى‬ ‫)غير‬
• Six sides : M.B & M. & M.Li. & D.B. & D. & D.Li.
• B.Li. : much greater than M.D.
• ELEVATIONS :
1. M.B. cusp ridge meets M.M.R. at right angle
2. D.B. cusp ridge meets D.M.R. at an acute angle
3. M.Li. and D.Li. Cusp ridges are curved
4. B. & Li. Triangle ridges are transverse ridge Mesiodistal marginal ridge
• DEPRESSION :
1. Central developmental groove
2. Mesiobuccal & mesiodistal developmental groove
3. Distobuccal & distolingual developmental groove
4. M. & D. developmental pits (‫)حفر‬
5. No supplemental grooves
6. 2 triangular fossa mesial & distal

10. Pulp cavity
• Root canals : 2 root canals buccal & lingual
• Lingual canal is larger and more accessible (‫إليه‬ ‫الوصول‬ ‫)سهل‬
• Cervical cross section : oval or kidney shaped
• Mesiodistal section : narrow
• Buccallingual section : wide

11. First Pre-Molar
• Have long buccal and sharp cusps assisting canine as a tearing tooth
• Cusp of first pre molar is sharp and long
• Tips of mesial are within the confines(‫)حدود‬ of the root trunk

12. Characteristics common to all posterior teeth and that
differ from those of anterior teeth
1) Greater B.Li. measurement than M.D.
2) Broader contact areas
3) Contact areas more nearly at the same level
4) Less curvature of the cervical line from all aspects
5) Shorter crown than anterior teeth