Premolars Revision - Dentition

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Premolars Revision - Dentition

  1. 1. BY Dr. Rehab Ali Lecturer Oral biology department
  2. 2. Maxillary first premolar It has 5 aspects: Buccal Lingual Mesial occlusal Distal
  3. 3. Maxillary second premolar It has 5 aspects: Buccal Lingual Mesial occlusal Distal
  4. 4. 1.5-2y 2-2.5y 4-5m Eruption Root completed 10-11 10-12 10-12 11-12 11 9 years 3+ 4 4 5 5 3 3 Crown completed years 5- Beginning of calc. (month)
  5. 5. Geometric outline of the crown • Facial and lingual aspects have trapezoidal out line. The smallest uneven side cervically.
  6. 6. Facial Outlines and surface anatomy of the crown 4 D M B cusp is long and pointed Longer M slope than D Mesial contact area in the M1/3 while distally more occlusal. Cervical line curved root wise. 5 D M B cusp is short and blunt Shorter M slope than D Mesial contact area at the jun. of O and M1/3 while distally more cervically. Cervical line less curved.
  7. 7. 4 D M 5 D M Prominent B ridge Less prominent B ridge Short root. Longer root.
  8. 8. Lingual outline and surface anatomy of the crown 4 The L cusp is shorter by 1 mm than the B cusp. 80%, 2 roots L root is shorter than B root. 5 The L and B cusps are nearly of same height (0.5 mm shorter) Rare to have 2 roots(20%) In case of two roots the L root is shorter.
  9. 9. Do or… you ..? like t o be a re al d ent i st
  10. 10. Geometric outline of the proximal aspect Distal aspect Trapezoidal in shape Mesial aspect Smallest uneven sides occlusaly
  11. 11. Mesial aspect 4 5 B cusp is longer than L cusp by 1mm The cusps are nearly at the same level. The occlusal table is wide. The occlusal table is wide,but narrower than 4. Mesial DG and canine fossa. Root trunk about half the root length. The crown surface is smooth and convex while root has shallow developmental depression.
  12. 12. Mesial aspect 4 MMR at the M1/3 Contact area: At the middle third (OC dimension) and slightly buccal to midline (BL dimension) 5 MMR positioned more occlusal. At the jun. of O and M 1/3 (OC dimension) and slightly buccal to midline (BL dimension)
  13. 13. Distal aspect 4 5 DMR more occlusal than MMR DMR more cervical than MMR CA occlusally positioned and more buccally than MCA. CA cervically positioned and more buccally than MCA.
  14. 14. Distal aspect 4 Root trunk is long as the bifurcation is near apical 1/3 Surface is smooth and convex except shallower DD on the root trunk than mesially. 5 One root and if 2 the bifurcation will be more apically. Surface is smooth and convex except deeper DD in the middle of the root than mesially.
  15. 15. Ih op e yo ua re b e tt er n ow ,
  16. 16. Occlusal aspect 5 4 D M It’s hexagonal D M It’s oval B & L triangular ridges. B & L triangular ridges. M & D marginal ridges Thicker M & D MRs
  17. 17. 4 5 Long Central DG Shorter Central DG. M developmental groove Not found. M and D M and D Not found. fossae. fossae. Supplemental grooves could be found (wrinkled)
  18. 18. Pulp cavity. MD section Root canals BL section 2 root canals (B&L) but rare 3 canals L canal is larger &more accessible Narrow Wide Pulp chamber In 5 one centralized large canal is present, but may two canals could be exist.
  19. 19. Mandibular first premolar It has 5 aspects: Buccal Lingual Mesial occlusal Distal
  20. 20. Mandibular second premolar :It has 5 aspects Buccal Lingual Mesial occlusal Distal
  21. 21. Geometric outline of the crown • Facial and lingual aspects have somewhat wider trapezoidal shape due to wider cervical third than 4.
  22. 22. Facial Outlines and surface anatomy 4 B cusp pointed and long Well prominent B ridge 5 B cusp short and less pointed Less prominent B ridge
  23. 23. Lingual outline and surface anatomy 4 5 Two cusp type The L cusp is short and small reaching 2/3 . the crown length and has a pointed tip L cusp is shorter and smaller than B cusp but larger than of 4 The lingual surface is convex with maximum convexity at M 1/3 The surface convex with .maximum convexity at O1/3 ML developmental groove at the ML .line angle No MLDG
  24. 24. :Three cusp type 5 ML cusp is longer and larger than M 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 N.B. Very little or no lingual .convergancy D
  25. 25. Proximal outlines 4 5 .Rhomboidal in shape with narrow occlusal table Lingual inclination well prominent Lingual inclination less prominent
  26. 26. 4 5 Maximum convexity at M1/3 Maximum convexity at O1/3 The L cusp is short and small reaching 2/3 the crown length .The B cusp centered over the root L cusp is shorter and smaller than B cusp but larger than of 4 B cusp tip on line with junction .of B & M 1/3 of the root The mesial MR is oblique while distally is straight The mesial and distal marginal ridges are straight
  27. 27. Proximal surface anatomy Distal aspect Mesial aspect . Contact area nearly at same level Contact area is broader, MCA is directly situated cervically and lingually below the B cusp ML developmental groove positioned. present at the junction of L . and M surfaces
  28. 28. 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
  29. 29. Geometric outline of the occlusal aspect 4 :Two cusp type .It’s diamond-shaped .Lingual convergence is sharp :Three cusp type The outline is square 5 The outline is oval Slight lingual convergence
  30. 30. :Surface anatomy of occlusal aspect 4 :Elevations 5 .B triangular ridge .L triangular ridge Transverse ridge M & D marginal ridges
  31. 31. 4 :Depressions 5 Central developmental groove Central developmental groove M and D triangular fossae )M fossa is oval while D fossa is circular,larger & deeper( snake eyes Mesiolingual developmental groove .(H or U shaped) .M and D triangular fossae both r circular,but D is) (deeper
  32. 32. :Three cusp type :Elevations .B triangular ridge (. L triangular ridges )ML &DL M & D marginal ridges :Depressions Developmental groove )Y shape formed of MB,DB & L .(grooves .M and D triangular fossae Central fossa with central pit. Remember the supplemental grooves!!!

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