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Upper First Pre-Molar
By:
Dr: Omar Abdelsalam
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
Chronology
First
Evidence of
Calcification
1.5-1.75
years
Enamel
Completed
5-6 years
Eruption
10-11 years
Root
completed
12-13 years
5
Aspects
Buccal
Lingual
Mesial
Distal
Incisal
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 .
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
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 .
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
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
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
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
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

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Upper First Pre-Molar.pptx

  • 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
  • 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