Premolars Revision - Dentition

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    07-May-2015

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  • 1.BYDr. Rehab Ali Lecturer Oral biology department

2. Maxillary first premolar It has 5 aspects:BuccalLingualMesial occlusalDistal 3. Maxillary second premolar It has 5 aspects:BuccalLingualMesialocclusalDistal 4. 1.5-2y 2-2.5y 4-5mEruptionRoot completed10-11 10-1210-12 11-1211 9years 3+4 4 5 5 3 3Crown completedyears 5-Beginning of calc. (month) 5. Geometric outline of the crown Facial and lingual aspects have trapezoidal out line. The smallest uneven side cervically. 6. Facial Outlines and surface anatomy of the crown 4DMB 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.5DMB 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. 4DM5DMProminent B ridgeLess prominent B ridgeShort root.Longer root. 8. Lingual outline and surface anatomy of the crown 4The L cusp is shorter by 1 mm than the B cusp. 80%, 2 roots L root is shorter than B root.5The 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. Do or you ..? like t obea re al d ent ist 10. Geometric outline of the proximal aspect Distal aspectTrapezoidal in shapeMesial aspectSmallest uneven sides occlusaly 11. Mesial aspect 45B cusp is longer than L cusp by 1mmThe 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. Mesial aspect 4MMR at the M1/3 Contact area: At the middle third (OC dimension) and slightly buccal to midline (BL dimension)5MMR positioned more occlusal. At the jun. of O and M 1/3 (OC dimension) and slightly buccal to midline (BL dimension) 13. Distal aspect 45DMR more occlusal than MMRDMR more cervical than MMRCA occlusally positioned and more buccally than MCA.CA cervically positioned and more buccally than MCA. 14. Distal aspect 4Root 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.5One 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. Ihop eyouare be tter now , 16. Occlusal aspect 54 DMIts hexagonalDMIts ovalB & L triangular ridges.B & L triangular ridges.M & D marginal ridgesThicker M & D MRs 17. 45Long Central DGShorter Central DG.M developmental grooveNot found.M and DM and DNot found.fossae.fossae.Supplemental grooves could be found (wrinkled) 18. Pulp cavity. MD sectionRoot canalsBL section2 root canals (B&L) but rare 3 canals L canal is larger &more accessible NarrowWidePulp chamber In 5 one centralized large canal is present, but may two canals could be exist. 19. Mandibular first premolar It has 5 aspects:BuccalLingualMesial occlusalDistal 20. Mandibular second premolar :It has 5 aspectsBuccalLingualMesialocclusalDistal 21. Geometric outline of the crown Facial and lingual aspects have somewhat wider trapezoidal shape due to wider cervical third than 4. 22. Facial Outlines and surface anatomy 4B cusp pointed and long Well prominent B ridge5B cusp short and less pointed Less prominent B ridge 23. Lingual outline and surface anatomy45Two cusp typeThe L cusp is short and small reaching 2/3 . the crown length and has a pointed tipL cusp is shorter and smaller than B cusp but larger than of 4The lingual surface is convex with maximum convexity at M 1/3The surface convex with .maximum convexity at O1/3ML developmental groove at the ML .line angleNo MLDG 24. :Threecusp type 5ML 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 .convergancyD 25. Proximal outlines 45.Rhomboidalin shape with narrow occlusal tableLingual inclination well prominentLingual inclination less prominent 26. 45Maximum convexity at M1/3Maximum convexity at O1/3The L cusp is short and small reaching 2/3 the crown length.The B cusp centered over the rootL cusp is shorter and smaller than B cusp but larger than of 4B cusp tip on line with junction .of B & M 1/3 of the rootThe mesial MR is oblique while distally is straightThe mesial and distal marginal ridges are straight 27. Proximal surface anatomy Distal aspectMesial 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. Mesial aspectDistal aspect:Three cusp type ML cusp is longer and larger than . DL cuspDL cusp is shorter and smaller . than ML cuspBoth lingual cusps are shorter than the buccal cusp and less pointed Surface anatomy is simillar to that of 4 29. Geometric outline of the occlusal aspect 4:Two cusp type.Its diamond-shaped .Lingual convergence is sharp:Three cusp type The outline is square5The outline is oval Slight lingual convergence 30. :Surface anatomy of occlusal aspect 4:Elevations5.B triangular ridge .L triangular ridge Transverse ridge M & D marginal ridges 31. 4:Depressions 5Central 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.(Hor U shaped).M and D triangular fossae both r circular,but D is) (deeper 32. :Three cusp type :Elevations .Btriangular 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!!!