Mandibular first premolar

1. Mandibular first premolar It has 5 aspects: Buccal Lingual Mesial Distal occlusal

2. Geometric outline of the crown • Facial and lingual aspects have trapezoid out line. The smallest uneven side cervically.

3. Facial Outlines Mesial and distal outlines are nearly concave B cusp pointed and long Mesial and distal cusp slopes are also slightly concave D M Contact areas: Mesially at the junction of O and M thirds while Distally it’s cervically positioned. Cervical line: is convex root wise.

4. Outline and surface anatomy of the root The M and D outline of the roots tapered to a pointed apex that curved distally. The surface of the root is convex and smooth

5. Surface anatomy of the crown Elevations: • The surface convex with maximum convexity at C 1/3represent………. • The middle lobe is prominent buccally forming BUCCAL ridge. Depressions: Shallow depressions were present mesial and distal to the B ridge

6. Lingual outline and surface anatomy of the crown M and D outlines are convex The L cusp is short and small reaching 2/3 the crown length and has a pointed tip. M D Cervical line: is convex root wise. Elevations: The lingual surface is convex with maximum convixty at M 1/3 Depessions: ML developmental groove at the ML line angle.

7. Geometric outline of the proximal aspect Mesial aspect Distal aspect Rhomboid in shape With narrow occlusal table Lingual inclination well prominent

8. Outlines of proximal aspect Mesial aspect Distal aspect Buccal outline is convex with maximum convexity at C 1/3 represent ……. Lingual outline is convex with maximum convexity at M1/3 Cervical line curves occlusally and decreased distally

9. Outlines of proximal aspect Mesial aspect Distal aspect Occlusal outline: the two cusps are not in same level (what’s the relation in between?) The B cusp centered over the root. This is due to the prominent lingual inclination. The L cusp tip in line with lingual border of the root.

10. Outlines of proximal aspect Mesial aspect Distal aspect MMR inclined from B to L surface \\ to B cusp ridge. DMRin 4 is straight and at right angle to the axis of the tooth. DMR is occlusal than MMR (unique characteristic of this tooth).

11. Proximal surface anatomy Distal aspect Mesial aspect M & D surfaces are smooth and convex except area cervical to contact area it’s concave. nearly at same level Contact area it’s broder, cervically and lingually positioned. ML developmental groove present at the junction of L and M surfaces.

12. Outline and surface anatomy of the root Mesial aspect Distal aspect B & L outlines are nearly straight cervically then taper to apically to a blunt apex The surface is smooth and flat with deep developmental groove The surface is more convex Note: The root may divided apically B & L

13. Geometric outline of the occlusal aspect It’s diamond-shaped. D M Lingual convergence is sharp. Mesial outline is slightly curved. Distal outline is more convex.

14. Surface anatomy of occlusal aspect: Elevations: B triangular ridge. L triangular ridge. M & D marginal ridges Transverse ridge

15. Depressions: Central developmental groove M and D triangular fossae. Mesiolingual developmental groove

16. Mandibular second premolar It has 5 aspects: Buccal Lingual Mesial Distal occlusal

17. Geometric outline of the crown • Facial and lingual aspects have somewhat square shape due to wide cervical third than 4.

18. Facial Outlines and surface anatomy 4 5 B cusp short and less pointed B cusp pointed and long Well prominent B ridge Not well prominent B ridge Pointed apex Blunt apex

19. Lingual outline and surface anatomy 4 5 Two cusp type L cusp is shorter and smaller than B cusp but larger than of 4 The L cusp is short and small reaching 2/3 the crown length and has a pointed tip. The lingual surface is convex with maximum convixty at M 1/3 The surface convex with maximum convixty at O1/3. ML developmental groove at the ML line angle. No MLDG

20. Three cusp type: 5 D M ML cusp is longer and larger than DL cusp. They both shorter than B cusp and less pointed. The surface convex with maximum convixty at O1/3. The L developmental groove between the 2 cusps

21. Proximal outlines 4 5 Rhomboid in shape with narrow occlusal table. Rhomboid in shape with narrow occlusal table. Lingual inclination well prominent Lingual inclination less prominent

22. 4 5 Maximum convexity at M1/3 Maximum convexity at O1/3 L cusp is shorter and smaller than B cusp but larger than of 4 The L cusp is short and small reaching 2/3 the crown length B cusp tip on line with junction of B & M 1/3 of the root. The B cusp centered over the root. The mesial MR is oplique while distally is straight The mesial and distal marginal ridges are straight

23. Mesial aspect Distal aspect Three cusp type: ML cusp is longer and larger than DL cusp. DL cusp is shorter and smaller than ML cusp. Both lingual cusps are shorter than the buccal cusp and less pointed Surface anatomy is simillar to that of 4

24. Geometric outline of the occlusal aspect Two cusp type: 4 5 The outline is oval It’s diamond-shaped. Lingual convergence is sharp. Slight lingual convergence Three cusp type: The outline is square

25. Surface anatomy of occlusal aspect: 4 5 Elevations: B triangular ridge. L triangular ridge. Transverse ridge M & D marginal ridges

26. 4 5 Depressions: Central developmental groove Central developmental groove H or U shapped. M and D triangular fossae. M and D triangular fossae. Mesiolingual developmental groove

27. Three cusp type: Elevations: B triangular ridge. L triangular ridges (ML &DL). M & D marginal ridges Depressions: Central developmental groove Y shape M and D triangular fossae.