dental anatomy lab Permanent Mandibular right first molar Summary

1. Summary
Permanent Mandibular Right First Molar (Larger Mandibular tooth)

2. •CROWN
•Trapezoidal outline.
•Contact area ;
Mesial- at junction between occlusal and middle third .
Distal- at center of middle third.
•Outline;
Mesial - concave at cervical third then convex near contact area.
Distal - straight above cervical line then convex near contact area.
•Buccal cusps;
1. mesiobuccal.
2. Distobuccal.
3. Distal(smaller more pointed).
4. Part of mesiolingual cusp and distolingual cusp.
•Cusps division = 9 mm
(4.5mm mesiobuccal cusp , 4.5mm distobuccal cusp, 2mm distal cusp).
•Lingual cusps longer than buccal cusps ~ 0.5mm.
•Cervical line; 1-Regular. 2- Dipping apically.
Buccal Surface
Parallel to
root
bifurcation
Parallel with
axis of distal
root
Mesiobuccal
groove
Distaobuccal
groove
Flat

3. •ROOT
•Two roots ;
1- mesial.
2- distal.
•Root Trunk 4 mm from cervical line to
Bifurcation.
•Interapical distance = 7 mm
( 2 mm mesial / 5 mm distal ).
Buccal Surface

4. •CROWN
• Buccal outline; convex above cervical line then straight.
Crest of curvature within cervical third.
• Lingual outline; straight above cervical line then straight from crest point
to the cusp tip .
Crest of curvature within middle third.
• Sulcus depth = 1mm.
• Intercuspal distance = 5 mm ( 2.5 Buccal , 2.5 Lingual).
• Lingual cusps longer than buccal cusps ~ 0.5 mm.
• Cusps in sight;
1- mesiobuccal.
2- mesiolingual.
• Mesial marginal ridge appears also.
Mesial Surface

5. •ROOT
•One root appears (Mesial)
•Mesial root hide distal root.
Mesial Surface

6. Occlusal Surface
•Hexagonal outline.
•Cusps (5);
1. Mesiobuccal.
2. Mesiolingual.
3. Distobuccal.
4. Distolingual.
5. Fifth (Distal cusp).
•Mesiobuccal cusp > each of the lingual cusps.
•Crown converge lingually from contact area.
•Two lingual cusps almost = each other.
1
2 4
3
5
Round
Lingual
Buccal
Distal
Mesial

7. •Fossae;
1- One major
A- Central.
2- Two Minors
A- Mesial triangular.
B- Distal triangular.
•Mesiodistal measurement larger than
Buccolingual measurement by 1mm.
•Buccolingual > on mesial than on distal.
Occlusal Surface
1A
2A 2B
Lingual
Buccal
Distal
Mesial

8. •Grooves;
1- Mesiobuccal developmental.
2- Distobuccal developmental.
3- Central.
4- Lingual developmental.
Occlusal Surface
1
2
4
3
Lingual
Buccal
Distal
Mesial

9. END