physiologyoftoothformfunctin1 TOOTH MORPHOLOGY.pptx

Best pdf for dental technology practitioners

1. TEETH MORPHOLOGIES

2. Form and Function Normal tooth form, plus proper alignment in the jaws, promotes efficiency during mastication, but in addition, the major portion of the form operates to insure the life of the tooth through stabilization. Form does not only means shape but also biomechanical attributes that contributes to maintenance. The relationship of tooth form to the form of the supporting structures, including gingiva must be considered in terms of clinical significance.

3. Protective Functional Form of the Teeth Includes: Proximal contact areas Interproximal areas (formed by proximal surface in contact) Embrasures (spillways) Height of contours ( labial & buccal contours at the cervical 3 rd , & lingual contour at the middle 3 rd ) Curvature of the Cemento -enamel junction ( curvature of cervical lines on the mesial & distal surfaces)

4. Proximal Contact Areas All teeth contact adjacent teeth at a proximal contact area except: distal of the last tooth In the arch diastemas pathology (caries) faulty restorations

5. Types of proximal contact POINT CONTACT- it is nothing but a misnomer, when the individual is quite young & the teeth are newly erupted , some of the teeth come close to having POINT CONTACT only. Eg . Distally on canines & mesially on premolars. CONTACT AREA- it is formed because of wear of one proximal surface against another during physiologic tooth movement.

6. Importance: Ensures food will not be packed between teeth causing inflammation to the supporting tissues thereby causing gingivitis & periodontitis It helps stabilize the dental arches by the combined anchorage of all the teeth in either arch in positive contact with each other (exception - third molars.) Each tooth is individually supported by these contact areas.

7. CONTACTS are OBSERVED from 2 views- Labial / buccal aspect- demonstrates the cervicoincisal / cervico - occlusal position Incisal / occlusal aspect- demonstrates the facio -lingual position

8. Anterior teeth have contacts that are generally centered faciolingually when view from the incisal Posterior teeth have contacts that are generally located buccal to the center of teeth when viewed from the occlusal

9. Proximal Contacts Maxillary Mesial Distal Central incisor Incisal 1/3 Junc of incisal/middle 1/3 Lateral incisor Junc of incisal/middle 1/3 Middle 1/3 Canine Junc of incisal /middle 1/3 Middle 1/3 1 st pre Middle 1/3 Middle 1/3 2 nd pre Middle 1/3 Middle 1/3 1 st molar Middle 1/3 Middle 1/3 2 nd molar Middle 1/3 Middle 1/3 3 rd molar Middle 1/3 n/a

10. Proximal Contacts Mandibular Mesial Distal Central incisor Incisal 1/3 Incisal 1/3 Lateral incisor Incisal 1/3 Incisal 1/3 Canine Incisal 1/3 Middle 1/3 1 st pre Middle 1/3 Middle 1/3 2 nd pre Middle 1/3 Middle 1/3 1 st molar Middle 1/3 Middle 1/3 2 nd molar Middle 1/3 Middle 1/3 3 rd molar Middle 1/3 n/a

11. Contact area move cervically from anterior to posterior in each quadrant On individual teeth the distal contact is more cervically located then the mesial contact Contacts increase in size from anterior to posterior 2 **Note: Contacts on incisors in incisal1/3, Where as contacts on molars in middle / 3

12. Contacts Mandibular Teeth : Contact their class counterpart and the tooth mesial Maxillary Teeth : Contact their class counterpart and the tooth distal

13. Interdental Areas Triangular in shape Base=alveolar bone Sides=prox. surfaces of teeth Apex=proximal contact area These triangular shaped areas are normally filled with gingival tissues

14. Embrasures The curvature formed by two adjacent teeth in an arch form a spillway space that is called an embrasure Note the Symmetry of the embrasure of the central incisors

15. Embrasures Embrasures are named relative to the contact area Facial or lingual views show the occlusal / incisal embrasures and cervical/ gingival embrasures Occlusal views show the buccal / labial and lingual embrasures

16. Significance of Embrasure form Serves as a spillway for food material during mastication Prevents food from being forced through the contact area and injuring the periodontal tissues. Also, Enhances the self-cleansing process of the tooth by exposing the surfaces to oral fluids, mechanical cleansing, and friction from the tongue, lips, and cheeks

17. Facial or lingual aspects: The incisal / occlusal embrasures increase in size from anterior to posterior The cervical embrasure decreases in size from anterior to posterior The incisal embrasure of the maxillary lateral/canine =greatest or longest The incisal embrasure of the maxillary canine/premolar= widest angle

18. Embrasures Mandibular posterior area occlusal view Arrows denote the facial and lingual embrasure areas The lingual embrasures are larger than the facial embrasures, because of lingual convergence of the crown.

19. Heights of Contours It is a line encircling a tooth In more or less horizontal plane, representing its greatest circumference . The facial and lingual contours: Protect the gingiva by the deflection of foods and help prevent trauma Lingual Buccal

20. The height of contour on both the facial and lingual surfaces of anterior teeth is located in the cervical third. Lingual Buccal

21. The height of contour of the buccal surfaces of posterior teeth is located in the gingival third The height of contour of the lingual surface of posterior teeth is located in the middle or occlusal third The average curvature is around 0.5mm, with mandibular posterior having a lingual curvature of 1mm. Mandibular anteriors having curvature of less than 0.5mm. Lingual Buccal

22. Height of Contours Maxillary Facial Lingual Central incisor Cervical 1/3 Cervical 1/3 Lateral incisor Cervical 1/3 Cervical 1/3 Canine Cervical 1/3 Cervical 1/3 1 st pre Cervical 1/3 Middle 1/3 2 nd pre Cervical 1/3 Middle 1/3 1 st molar Cervical 1/3 Middle 1/3 2 nd molar Cervical 1/3 Middle 1/3 3 rd molar Cervical 1/3 Middle 1/3

23. Height of Contours Mandibular Facial Lingual Central incisor Cervical 1/3 Cervical 1/3 Lateral incisor Cervical 1/3 Cervical 1/3 Canine Cervical 1/3 Cervical 1/3 1 st pre Cervical 1/3 Middle 1/3 2 nd pre Cervical 1/3 Middle 1/3 1 st molar Cervical 1/3 Middle 1/3 2 nd molar Cervical 1/3 Middle 1/3 3 rd molar Cervical 1/3 Middle 1/3

24. OVERCONTOURED RESTORATIONS- a restoration containing so much excess restorative material that normal anatomic structure is altered; may cause plaque retention and open or deficient gingival margin. UNDERCONTOURED RESTORATIONS- a restoration containing too little restorative material so that a space occurs between the margin and the cavity wall; may result when either the matrix band or wedge is improperly placed.

25. Curvature of the CEJ The CEJ is a stable line whose curvature is related to the widths and lengths of the crown and the location of the contact areas interproximally The extent of the curvature depends on- Height of the contact area above the crown cervix Diameter of the crown labiolingually .

26. The CEJ is curved toward the apical on the facial and lingual surfaces of teeth The CEJ is curved toward the incisal or occlusal surfaces on the proximal surfaces of teeth The depth of the curvature is greater on the mesial than on the distal aspect The depth of curvature on the CEJ on all surfaces is greater on anterior teeth and decreases toward the posterior

27. Axial Alignment The alignment of teeth within the dental arches. All teeth are mesially inclined, with the possible exception of the most distal maxillary teeth. Maxillary teeth are inclined facially Mandibular posterior teeth are inclined lingually Mandibular anterior teeth are inclined facially

28. L MAXILLARY CENTRAL INCISOR abial It is the widest tooth in the maxillary arch . The mesial margin is straight and meets the incisal edge at right angle. The distal margin is shorter and more rounded. The distoincisal angle is more rounded than the mesioincisal angle. Mesial margin straight & meets at 90 degree Distal margin shorter & rounded Distoincisal angle more rounded, making an obtuse angle Mesioincisal angle rounded, making somewht 90 degrees

29. The labial surface is marked by two developmental groove and has convexity in cervical third . Mesiodistally the crown is narrowest cervically , & becomes broadest in the incisal 3 rd . Convexity in cervical third a b

30. Lingual aspect The crown profile is same as that of labial surface except that there is a broad depression in the central portion called the lingual fossa and a well developed cingulum . Maxillary incisor with a deep & large lingual fossa & prominent mesial & distal marginal ridges are called as SHOVEL SHAPED INCISOR Due to the distal displacement of the cingulum , the mesial marginal ridge is slightly LONGER than the distal marginal ridge Lingual fossa Cingulum Marginal ridges Lingual ridge

31. The lingual fossa is bordered by mesial and distal marginal ridges on the sides and the cingulum cervically. The cervical line on labial and lingual surface is convex apically . Cervical line convex Lingual aspect Labial aspect

32. Mesial aspect From this aspect the crown appears WEDGE SHAPED, with base of traingle at cervix & apex towards the incisal edge. From the mesial aspect the labial margin is convex The lingual margin is ‘S’ shaped, being convex near cingulum and concave in the middle Labial margin convex Convex near cingulum Concave in the middle

33. Mesial curvature of cervical line (3.5mm) is the most pronounced compared to any other tooth. The cervical line on the mesial and distal surface is convex incisally Cervical line

34. Distal aspect Distal aspect Distal surface is very similar to the mesial surface. when central incisor viewed from distal aspect, the crown gives the impression of somewhat thicker towards the incisal 3 rd , this is because the distoincisal angle is slightly lingually positioned than mesioincisal angle.

35. Incisal aspect The crown and incisal margin are centered over root Crown profile is almost bilaterally symmetrical The incisal margin of newly erupted teeth show three elevations called mamelons . The middle One is smallest.They correspond to the developmental lobes. Incisal ridge Bilaterally symmetrical

36. Root The root is straight and tapers from the cervical line to the apex giving it a conical shape The root ends in a blunt apex . Root : crown ratio is 1.3:1.05 Straight conical blunt root 3.5 2.5 6.0 7.0 7.0 8.5 13.0 10.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter of crown Root Length Crown Length Average Dimensions in millimeters

37. Maxillary Lateral Incisor The general shape is similar to maxillary central incisors except that they are shorter and narrower. Next to third molars maxillary lateral incisors are the teeth that show most variation in crown size, shape and form Maxillary central incisor bigger and lateral incisor smaller

38. The mesioincisal and distoincisal angles are more rounded than the corresponding angles of the maxillary central incisor Distoincisal angle more rounded Mesioincisal angle more rounded Maxillary Lateral Incisor Maxillary Central Incisor Mesioincisal angle Distoincisal angle

39. On the lingual aspect the marginal ridges and cingulum are more prominent Prominent cingulum Prominent marginal ridges

40. MAXILLARY CENTRAL INCISOR MAXILLARY LATERAL INCISOR LABIAL VIEW 1. CROWN IS LARGER CROWN IS SMALLER 2. MESIOINCISAL ANGLE AT 90 DEGREE & DISTOINCIAL ANGLE SLIGHTLY ROUNDED MESIOINCISAL ANGLE IS ACUTE & DISTOINCISAL ANGLE ROUNDED 3. MESIAL CONTACT AREA AT INCISAL 3 rd DISTAL CONTACT AREA AT JUNC OF INCISAL & MIDDLE 3 rd .

41. LINGUAL VIEW 1. LINGUAL FOSSA LARGER & SHALLOWER LINGUAL FOSSA SMALLER & MORE CONCAVE. 2. LINGUAL PITS ARE LESS FREQUENT LINGUAL PITS ARE COMMON 3. CINGULUM IS POSTIONED SLIGHTLY DISTALLY CINGULUM IS CENTERED

42. PROXIMAL VIEW 1. CERVICAL LINE CURVATURES ARE MORE CURVATURE IS LESS 2. ROOT IS EVENLY TAPERED ROOT IS MORE CONVEX

43. INCISAL 1. CROWN WIDER MESIODISTALLY THAN FACIOLINGUALLY CROWN SAME BOTH MESIODISTALLY & FACIOLINGUALLY 2. CROWN OUTLINE IS TRIANGLULAR CROWN OUTLINE IS ROUNDED OR OVAL 3. CINGULUM SLIGHTLY DISTAL CINGULUM CENTERED 4. INCISAL RIDGE SLIGHTLY CURVED MESIODISTALLY INCISAL RIDGE RELATIVELY STRAIGHTER MESIODISTALLY

44. MANDIBULAR INCISOR Mandibular central incisor and lateral are similar in anatomy and complement each other in function . L abial aspect Labial surface of mandibular central incisor is very small. It is the narrowest tooth mesiodistally of all the permanent teeth Narrowest tooth in the dentition

45. It is bilaterally symmetrical,that it is difficult to tell the sides. The only differnce is the greater mesial than distal curvature. It is the only incisor where both mesioincisal and distoincisal angles are sharp and at right angles Both mesioincisal and distoincisal angles are sharp

46. Lingual aspect The lingual aspect is concave from the incisal edge to the cervical line Cingulum is smooth, barely visible & no development lines mark the cingulum . Marginal ridges almost absent The surface is smooth and devoid of any grooves. No other tooth in the mouth, except the mandibular lateral incisor, shows so few developmental lines and grooves. No lingual pit is present. Root is slightly narrower on the lingual side than on the labial side.

47. Mesial aspect Crown is wedge shaped, with t he labial outline is almost straight, except near cervical third where it is convex. The labial surface is inclined lingually Root has longitudinal shallow depressions on the middle 3 rd of mesial root surfaces. Labial surface inclined lingually

48. The lingual margin is ‘S’ shaped The cervical line on the mesial and distal surface is convex incisally ‘S’ shaped lingual surface Cervical line convex incisally

49. Distalaspect Distal surface is very similar to the mesial surface. The cervical line is less curved. Distal aspect

50. Incisal aspect This aspect illustrates the bilateral symmetry of this tooth. The incisal edge or ridge is at right angles to the labiolingual root axis plane. The labiolingual diameter is greater than mesiodistal diameter. Newly erupted teeth show mamelons which wear off upon mastication Bilaterally symmetrical Labiolingually bigger than mesiodistally Mamelons

51. Root The root is single and straight. The deflection of the root if present is on the labial or distal side . Root : crown ratio is more in all mandibular teeth 3.0 2.0 5.3 6.0 3.5 5.0 12.5 9.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

52. Mandibular Lateral Incisor Mandibular lateral incisor is slightly wider mesiodistally The distal side of the crown from the labial aspect is slightly bulging in comparison to mesial flatter surface. The crown is slightly tilted distally on the root, & due to this tilt the distal outline of the crown is shorter in length than the mesial outline. Bilateral symmetry not seen, Cingulum slightly towards the distal.

53. The cervical portion of the lingual aspect is narrower while the incisal portion is wider. This gives the crown a more or less a fan shaped appearance Cervical portion narrower Fan shaped appearance

54. The concavity in the lingual aspect is slightly more when compared to mandibular central incisor The incisal edge follows the mandibular arch, giving the crown a slightly twisted appearance on its root Lingual fossa more concave 3.0 2.0 5.8 6.5 4.0 5.5 14.0 9.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

55. MANDIBULAR CENTRAL INCISOR MANDIBULAR LATERAL INCISOR 1. CROWN MORE SYMMETRICAL LESS SYMMETRICAL 2. CROWN & ROOT ARE SHORTER CROWN & ROOT ARE LONGER 3 NO DISTAL SIDE BULGE ON CROWN DISTAL SIDE BULGE ON CROWN 4. CINGULUM CENTERED CINGULUM DISTAL TO CENTRE 5. NO DISTOLINGUAL TWIST OF INCISAL EDGE DISTOLINGUAL TWIST OF INCISAL EDGE 6. MARGINAL RIDGES NOT PROMINENT LONGER MESIAL MARGINAL RIDGE

56. MAXILLARY INCISORS MANDIBULAR INCISORS LABIAL 1. CROWN MESIODISTALLY WIDER & LESS SYMMETRICAL CROWN IS LONG, NARROW & MORE SYMMETRICAL 2. DISTOINCISAL ANGLES MORE ROUNDED MESIOINCISAL SHARP, & DISTOINCISAL ANGLES ARE SLIGHTLY ROUNDED 3. SHALLOW LABIAL DEPRESSIONS ARE COMMONLY PRESENT NOT PRESENT LINGUAL 1. LARGER CINGULUM SMALLER CINGULUM 2. DEEPER LINGUAL FOSSA SHALLOW FOSSA 3. SOMETIMES LINGUAL PITS PRESENT LINGUAL PITS ABSENT 4. PROMINENT MARGINAL RIDGES LINGUAL SURFACE SMOOTH, WITHOUT MARGINAL RIDGES 5 CINGULUM SLIGHTLY DISTAL CENTRAL ALMOST SYMMETRICAL PROXIMAL 1. CINGULUM IS PROMINENT VERY SMALL CINGULUM 2. INCISAL EDGE LABIAL TO ROOT AXIS INCISAL EDGE LINGUAL TO ROOT AXIS

57. INCISAL 1. CROWNS ARE WIDER MESIODISTALLY THAN FACILINGUALLY CROWNS WIDER FACIOLINGUALLY THAN MESIODISTALLY 2. INCISAL EDGE LABIAL TO ROOT AXIS INCISAL EDGE LINGUAL TO ROOT AXIS 3. CINGULUM OF CI IS SLIGHTLY DISTAL CINGULUM OF LI IS IN CENTRE CINGULUM OF CI IS CENTERED CINGULUM OF LI IS SLIGHTLY DISTAL 4. LABIAL SURFACE OF LI IS SLIGHTLY CONVEX CENTRAL & LATERALS HAVE ALMOST FLAT LABIAL SURFACES AT INCISAL & MIDDLE 3 rd .

58. MAXILLARY CANINES Canines are very long and stable teeth There are four canines placed at the corner of the mouth and hence called the ‘corner stones’ of the dentition They have a single pointed cusp (also called cuspids )

59. Labial aspect The crown of maxillary canine is narrower mesiodistally than that of maxillary central incisor. The incisal aspect has a large cusp with a pointed cusp tip It has two slopes (cusp ridges), the mesial slope being shorter than the distal slope The labial surface is smooth and bulky in the middle because of the labial ridge, which runs cervicoincisally . All areas lies mesial to this ridge shows more convexity, while distal shows less convexity.

60. Labial aspect Labial ridge Cusp tip Distal cusp ridge Mesial Cusp Ridge

61. Lingual aspect The crown and root are narrower lingually The cingulum is well developed, large and sometimes pointed like a cusp & in center. Occasionally a well developed lingual ridge is seen that divides the lingual fossa into mesial and distal lingual fossae Heavy marginal ridges are associated with well formed cingulum and fossae

62. Lingual aspect Cingulum Distal marginal ridge Distal lingual fossa Lingual ridge Mesial marginal ridge Mesial lingual fossa

63. Mesial aspect Crown outline is wedge shaped From the mesial aspect canine looks similar but bulkier than maxillary central incisor Maxillary canine is the widest anterior tooth labiolingually The cervical line curvature is towards the cusp ( incisally ) The contact area is near the junction of the incisal and middle third From this aspect the entire labial otline is convex from the cervical line to the cusp tip, & the lingual outline is convex at cingulum , thereafter it straightens out at the middle 3 rd & again slight convex in the incisal 3 rd .

64. Mesial aspect

65. Distal aspect Distal surface is very similar to the mesial surface The cervical line exhibits less curvature The contact area is near the middle third, Distal aspect

66. Incisal aspect The labiolingual dimension is greater than the mesiodistal dimension The cusp tip is labial to the centre of the crown labiolingually and mesial to the centre mesiodistally Mesiodistally , the mesial half of the crown is narrower, than the distal half. The labial ridge and the cingulum are very noticeable from this aspect. The mesial half of labial outline is more convex, than the distal half

67. Root – only one The root is the longest and strongest of all the teeth in the dentition The mesial and distal surfaces of the root have developmental depressions . 2.5 1.5 7.0 8.0 5.5 7.5 17.0 10.0 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

68. Mandibular Canine Labial aspect Mandibular canines are similar to maxillary canines except that they are slightly narrower mesiodistally Mesial outline of the crown is almost straight and inline with the mesial outline of the root. The crown is more towards the distal to the root axis than mesial to it. Because of this crown appears to be distally tilted when the roots are held vertical position. Cusp tip forms a more obtuse line (120 degree) Labial ridge is very rudimentary, & not as marked as maxillary canine. The mesial cusp ridge is smaller than the distal cusp ridge

69. Lingual aspect The lingual surface of the crown is smooth and flat simulating the surface of mandibular lateral incisor Cingulum is less prominent and marginal ridges are less distinct Mesial and Distal aspects These aspects are very similar and the cervical line curves more on the mesial aspect The contact area on mesial aspect is in the incisal third and a little higher on the distal third Incisal ridge is slightly lingual to the root axis. The distoincisal angle is slightly more lingual in position than the cusp tip to give turn to the arch.

70. Incisal aspect Like maxillary canine the labiolingual dimension is more than the mesiodistal dimension The cusp tip appears inclined in a lingual direction The root is shorter by 1 or 2 mm The developmental depression is more pronounced on the lower canine 2.5 1.0 7.0 7.5 5.5 7.0 16.0 11.o Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

71. MAXILLARY CANINE MANDIBULAR CANINE LABIAL 1. APICAL ROOT TIP IS DISTALLY BENT CROWN IS SLIGHTLY TIPPED DISTALLY ON ROOT 2. 3. 4. 5. MESIAL SIDE OF THE CROWN IS LESS CONVEX, WHILE DISTAL IS MORE CONVEX MORE ACUTE CUSP TIP i.e 105 DEGREE LABIAL RIDGE IS MORE PRONOUNCED BLUNT ROOT TIP MESIAL SIDE OF CROWN IS ALMOST IN STRAIGHT LINE WITH THE MESIAL SIDE OF THE ROOT. 120DEGREE LABIAL RIDGE IS LESS PRONOUNCED POINTED ROOT TIP 120 degree 105 degree

72. LINGUAL 1. CINGULUM IN CENTRE SLIGHTLY DISTAL TO THE CENTRE 2. STRONG LINGUAL RIDGE & POOR DISTAL MARGINAL RIDGES. DISTAL MARGINAL RIDGE IS MORE PROMINENT & SMOOTH SURFACE

73. PROXIMAL 1. ROOT DEPRESSION IS MORE DISTINCT ON THE DISTAL SIDE THAN ON THE MESIAL SIDE DISTAL ROOT DEPRESSION IS LESS 2. CUSP TIP LABIAL TO ROOT AXIS CUSP TIP LINGUAL TO ROOT AXIS

74. INCISAL 1. 2. CROWN IS ASYMMETRICAL, WITH MORE BUCCOLINGUAL BULK IN MESIAL HALF, DISTAL HALF IS THINNER. LESS DISTLINGUAL CROWN TWIST DISTAL HALF IS SLIGHTLY THICKER. MORE DISTOLINGUAL CROWN TWIST. 3. ATTRITION OF CUSP TAKES PLACE LINGUALLY ATTRITION OF CUSP TAKES PLACE LABIALLY 4. INCISAL OUTLINE IS ASYMMETRICAL INCISAL OUTLINE IS SYMMETRICAL 5. CUSP TIP- LABIAL TO CENTER LINGUAL TO CENTER 6. MORE BULKY CUSP TIP DUE TO HEAVY LINGUAL RIDGE CUSP TIP & LINGUAL RIDGE IS LESS BULKY

75. MAXILLARY PREMOLARS Premolars are so named because they are placed between the anterior teeth and the molars Maxillary premolars have two cusps and sometimes one or two roots They develop from four lobes, like anterior teeth.

76. Buccal aspect The crown is roughly TRAPEZOIDAL This tooth has two cusps, buccal and lingual cusps . The buccal cusp is long with a pointed tip resembling the cusp of a canine TIP of buccal cusp lies DISTAL to the line bisecting the buccal surface of crown. The mesial slope of the buccal cusp is longer than the distal slope, which is the opposite of canine The buccal surface is convex, showing a strong buccal ridge The crown exhibits little cervical line curvature Mesial & distal side of the buccal ridge from the occlusal to the middle 3 rd , shows development depressions k/a mesiobuccal & distobuccal development depressions.

77. Lingual aspect crown tapers towards the lingual aspect Mesial outline of the crown is convex. Distal outline is straight. The lingual cusp is shorter than the buccal cusp The lingual cusp is smooth from the cervical portion to the area near the cusp tip The cusp tip is pointed with mesial and distal slopes meeting at an angle of about 90 degrees 90 degree

78. Sometimes lingual ridge is present, formed by termination of crest of lingual portion at a point. Small portion of the buccal cusp can be seen from this aspect Lingual root is slightly shorter than the buccal root. Apex of lingual root- more blunt buccal root- pointed.

79. Mesial aspect From this aspect crown appears roughly TRAPEZOIDAL, with longest uneven arm Towards the cervical 3 rd , while shortest Arm at occlusal 3 rd . From this aspect both the buccal and lingual cusps are visible Tips of cusp are within the confines of root trunk of the same side A well developed mesial marginal ridge and a mesial marginal developmental groove is present Buccal outline- curves outwards from the cervical line till the crest of curvature, & from crest of curvature it shows less convexity.

80. Lingual outline from cervical 3 rd to the lingual cusp tip forms a smooth curve. There is a depression at just cervical to the mesial contact area k/a MESIAL DEVELOPMENTAL DEPRESSION.. This feature differentiates it from right & left & also from second premolar ROOT- The outline of the crown bucally is straight, with a tendency towards the lingual inclination Lingual outline also straight. Bifurcation is present at half of total length of root.

81. Distal aspect There is no developmental depression or groove on this aspect, instead it is convex at almost all points The curvature of the cervical line is less on this aspect The contact area is near the junction of occlusal and middle third. Bifurcation of root is more towards the apical 3 rd .

82. Occlusal aspect The occlusal aspect is roughly hexagonal(6 sided i.e MB, M,ML,DB,D,DL) in shape. With mesial side shorter than the distal side. Buccal sides are nearly equal. Mesiolingual side is shorter than distolingual side. The buccolingual dimension of the crown is much greater than the mesiodistal dimension The occlusal surface is circumscribed by the cusp ridges and marginal ridges

83. Following structures can be seen- The distance from the buccal crest to the distal crest is shorter than the distance from the buccal crest to mesial crest. The distance from the mesial crest to the lingual crest is much shorter than the distance from the distal crest to the lingual crest. Buccal portion of the crown is more wider than the lingual portion. Central developmental groove- Runs mesiodistally with pits at both ends. The length of central groove is more than one third of the mesiodistal width of occlusal surface.

84. Mesial marginal developmental Groove- it crosses the mesial marginal ridge. This groove connects the central groove in the mesial triangular fossa . Distal marginal groove may be found, but less frequent than mesial marginal groove Mesial and distal developmental pit are closer to each other than in 2 nd premolar. Mesial and distal triangular fossa Buccal and lingual triangular ridge, buccal ridge more prominent arising from the central groove & converging with the tip of the buccal cusp. Lingual cusp is more pointed, than buccal cusp.

85. Root Most Maxillary first premolars have 2 roots, but one and three roots can also be seen. Two roots; buccal and lingual The buccal portion of the root resembles canine The root when viewed from the proximal side shows a big trunk and bifurcation area from where the buccal and lingual root separate A developmental depression is seen on the mesial aspect of the trunk.

86. 1.0 0 8.0 9.0 5.0 7.0 14.0 8.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

87. Maxillary 2 nd Premolar Buccal aspect The maxillary second premolar resembles the maxillary first premolar in form and function The buccal cusp is not as long as that of maxillary 1 st premolar It is less pointed. The mesial slope of the buccal cusp ridge is shorter than the distal cusp ridge, as in maxillary canine. Crown & root are thicker at the cervical portion.

88. Lingual aspect The lingual cusp is more or less the same size as the buccal cusp Root is single, & tapered towards apex & towards the lingual side. Mesial and Distal aspects There is greater distance between the cusps which widens the occlusal surface buccolingually . No developmental depression is present nor any developmental groove crossing the marginal ridge on the mesial aspect On the distal aspect there is a developmental depression which is deeper than the depression on the mesial surface of maxillary 1 st premolar

89. Occlusal aspect The occlusal aspect is more rounded/ oval The central developmental groove is shorter, & mesial marginal groove is absent. Triangular fossae are smaller & farther from marginal ridges. Mesiodistal diameter is more on the buccal side than the lingual side. There are multiple supplementary grooves radiating from the central groove

90. Root Maxillary 2 nd premolar has one root, which is usually as long or a millimeter longer than the root of maxillary 1 st premolar 1.0 0 8.0 9.0 5.0 7.0 14.0 8.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

91. MAXILLARY 1 ST PREMOLAR MAXILLARY 2 ND PREMOLAR BUCCAL 1. BUCCAL RIDGE IS PROMINENT NOT PROMINENT 2. MESIAL CUSP SLOPE IS LONGEST MESIAL CUSP SLOPE SHORTEST 3. CERVIX NARROW & TAPERS MORE CERVIX BROAD & TAPERS LESS

92. LINGUAL 1. LINGUAL CUSP SHORTER THAN BUCCAL CUSP LINGUAL CUSP ALMOST EQUAL TO BUCCAL CUSP 2. CROWN NARROWER & MORE TAPERS TOWARDS LINGUAL LESS TAPER TOWARDS LINGUAL

93. PROXIMAL 1. TWO ROOTS ONE ROOT 2. BUCCAL CUSP IS LONGER THAN LINGUAL BUCCAL & LINGUAL OF SAME LENGTH 3. CUSP TIP ARE CLOSE TOGETHER CUSP TIPS ARE SPREAD APART 4 MESIAL MARGINAL RIDGE GROOVE IS PRESENT MESIAL MARGINAL RIDGE GROOVE IS ABSENT

94. OCCLUSAL 1. LONGER CENTRAL GROOVE SHORTER CENTRAL GROOVE 2. MORE CONVERGENCE OF PROXIMALS TOWARDS LINGUAL SLIGHT CONVERGENCE TOWARDS LINGUAL 3. PROMINENT BUCCAL RIDGE LESS PROMINENT RIDGE 4. BUCCAL CUSP INCLINES ARE LONGER THAN LINGUAL LINGUAL CUSP INCLINES ALMOST EQUAL TO BUCCAL

95. 6. VERY FEW SUPPLEMENTARY GROOVES MORE SUPPLEMENTARY GROOVES 7. MESIAL SIDE SHORT & SLIGHTLY CONCAVE OR FLAT DISTAL SIDE CURVED OR CONVEX OR LONGER BOTH MESIAL & DISTAL OUTLINES OF CROWN ARE MORE SYMMETRICAL 8. CROWN OUTLINE HEXAGONAL CROWN OUTLINE IS OVAL 9. MESIAL MARGINAL RIDGE GROOVE IS PRESENT IN 97% OF CASES LESS COMMON, PRESENT IN ONLY 37% OF CASES 10. MESIOBUCCAL CUSP RIDGE & MARGINAL RIDGE MEETS AT RIGHT ANGLE MESIOBUCCAL CUSP RIDGE & MARGINAL RIDGE MEETS AT OBTUSE

96. Mandibular First Premolar

97. Buccal aspect A large well formed, pointed buccal cusp is seen.. The mesiobuccal cusp ridge is shorter than the distobuccal cusp ridge (similar to canines ) Tip of buccal cusp is located a liitle MESIAL to the centre of the crown buccally . The mesial and distal slope of the buccal cusp sometimes show concavity. Mesial & distal outline of the crown is Slightly concave above the cervical line.

98. Lingual aspect The crown tapers and inclines lingually , Making it narrower mesiodistally The lingual cusp is small, pointed and nonfunctional and in some specimens it is no longer than the cingulum of maxillary canine. Between the mesiobuccal and lingual lobe is the mesiolingual developmental groove, & extends into the mesial fossa of Occlusal surface. This grooves separates the mesial marginal ridge from mesial slope of lingual cusp. Occlusal surface slopes greatly towards the lingual in a cervical direction down to the short lingual cusp.

99. Root tapers more on the lingual side. A smooth convex narrow linear ridge runs along the full length of the root, because of this ridge & lingual taper most of the proximal surface is visible from this aspect.

100. Mesial aspect The lingual inclination of the crown can be seen from this aspect,because of which the tip of buccal cusp is nearly centered over the root axis Buccal outline is prominently curved. Crest of curvature on buccal side- just occlusal To the cervical line, lingual side- near the tip of the lingual cusp. The lingual cusp is approximately two thirds the size of the buccal cusp The mesial marginal ridge has extreme lingual slope, it is located cervically as compared to distal marginal ridge. The mesial marginal ridge is almost parallel to the triangular ridge of the buccal cusp, & slopes cervically From bucccal towards the centre of occlusal surface at 45 Degree angle. 2/3rd

101. Mesiolingual developmental groove is present between the mesial marginal ridge and the mesiolingual cusp ridge The distal contact areas are in the middle third,. Root- buccal & lingual outline almost runs parallel in cervical & middle 3 rd , then tapers apically to end in a pointed apex, situated in line with buccal cusp tip.

102. Distal aspect Convexity on the distal surface is less as compared to mesial surface. Distal marginal ridge is higher ( occlusal ) and does not have the extreme lingual slope The cervical line curvature is less curved. Root surface is more convex as compared to mesial surface. A shallow linear developmental depression On distal root surface.

103. Occlusal aspect The crown converges sharply to the centre of the lingual surface Crown appears asymmetrical, being somewhat DIAMOND SHAPE. distal outline is more convex, there appears to be more bulk in the distal half of occlusal aspect. Most common form of mandibular 1st premolar shows a mesiolingual depression and mesiolingual developmental groove.

104. The occlusal surface has two depressions; mesial and distal fossae , both of them are circular in shape, hence not termed as triangular fossae Mesial fossa is more linear, & contains mesial developmental groove, extending buccolingually . Distal fossa is more circular in shape & harbours a cresent shaped distal developmental grove. Mesial marginal ridge is at an acute angle with the mesiobuccal cusp ridge Distal marginal ridge is at right angle to the distobuccal cusp ridge. Distal ridge more bulky than mesial marginal ridge.

105. Root The mandibular 1st premolar has one root The root is approximately (3-4mm)shorter than the root of mandibular canine but the outline bears a close resemblance to the canine A deep developmental groove is seen on the mesial aspect on the root On the distal aspect there is a shallow depression devoid of any developmental groove .

106. 1.0 0 6.5 7.5 5.0 7.0 14.0 8.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

107. Mandibular Second Premolar Mandibular 2nd premolar resembles the mandibular 1st premolar from the buccal aspect only The crown assumes two common types. more common 3-cusp type- more angular 2-cusp type- more rounded The two differ mainly in the occlusal design Buccal aspect The buccal cusp is shorter with the cusp slopes presenting less degree of angulations

108. Lingual aspect There may be one or two lingual cusps – mesiolingual and distolingual cusps The cusp are more developed than the lingual cusp of lower first premolar groove separates the two lingual cusps. 2 cusp type- no groove but a distolingual developmental depression appears where the lingual cusp ridge joins the distal marginal ridge 3 cusp type- there is a longer mesiolingual & a comparatively smaller distolingual cusp. A groove is present between the two cusps

109. Mesial and Distal aspects The crown and root are wider buccolingually Buccal cusp is shorter. Mesiolingual developmental groove absent More of occlusal surface is visible form the distal aspect because the distal marginal ridge is at lower level than the mesial marginal ridge

110. Occlusal aspect From the occlusal aspect the 3-cusp type appears square and the 2-cusp type appears rounded . 3-cusp type : each cusp is separated by deep developmental grooves forming a “Y” shape in the centre - BUCCAL cusp largest, then ML & DL shortest. - the occlusal surface also includes a . central pit b . mesial developmental groove travels in a mesiobuccal direction & ends in mesial triangular fossa c. mesial triangular fossa d . distal developmental groove travels in a distobuccal direction & end in distal triangular fossa . e. distal triangular fossa f. lingual developmental groove g. supplemental grooves

111. 2-cusp type: - one buccal cusp and one well developed lingual cusp is present - crown outline is less oval on the lingual side. - a central groove travels in a mesiodistal direction and end in mesial and distal fossa (forming ‘H’ shape) - buccolingual bulk is more in the mesial half than the distal half Root- Mandibular 2 nd premolar has a single root which is larger and longer than the root of mandibular 1 st premolar The root is usually wide with a blunt apex

112. MANDIBULAR 1 ST PREMOLAR MANDIBULAR 2 ND PREMOLAR BUCCAL 1. PRESENCE OF LONGER BUCCAL CUSP CROWN IS SHORTER BUT WIDER. 2. MORE POINTED CUSP(110 DEGREE) ROUNDED CUSP (130 DEGREE) 3. NOTCH PRESENT ON MESIAL CUSP SLOPE NOTCH ON DISTAL CUSP SLOPE 4. LINGUAL SURFACE MORE TAPER FROM CONTACTS TO CERVIX LINGUAL SURFACE RELATIVELY WIDER AT CERVIX 5. ROOT IS SHORTER WITH POINTED APEX ROOT IS LONGER WITH BLUNT APEX 6. BUCCAL RIDGE MORE PROMINENT LESS PROMINENT 110 DEGREE 130 DEGREE

113. LINGUAL 1. CROWN IS NARROWER THAN SECOND PREMOLAR CROWN IS WIDER 2. LINGUAL CUSP IS SHORT & NARROW & NONFUNCTIIONAL LINGUAL CUSP LARGER & FUNCTIONAL 3. FROM THIS ASPECT MORE OF OCCLUSAL SURFACE IS VISIBLE VERY LESS OCCLUSAL SURFACE IS VISIBLE 4 MESIAL MARGINAL RIDGE IS DIVIDED BY MESIOLINGUAL GROOVE MESIAL MARGINAL GROOVE IS ABSENT

114. PROXIMAL 1. LINGUAL CUSP MUCH SHORTER THAN BUCCAL CUSP & NON FUNCTIONAL LINGUAL CUSP ONLY SLIGHTLY SHORTER THAN BUCCAL CUSP & IS FUNCTIONAL 2. CROWN IS MORE TILTED TO LINGUAL SIDE CROWN IS LESS TILTED TO LINGUAL SIDE 3 MESIAL MARGINAL RIDGE IS LOWER & PARALLEL TO TRIANGULAR RIDGE OF BUCCAL CUSP, HENCE MUCH OF OCCLUSAL SURFACE IS VISIBLE MESIAL MARGINAL RIDGE IS HIGH & IS IN HORIZONTAL PLANE, HENCE ONLY LITTLE OCCLUSAL SURFACE IS VISIBLE 4. ROOTS HAVE DEEP LONGITUDINAL DEPRESSIONS NO DEPRESSIONS PRESENT.

115. OCCLUSAL 1. CROWN OUTLINE IS ASYMMETRICAL OUTLINE IS SQUARE 2. SMALL OCCLUSAL & LESS GRINDING SURFACE LARGE OCCLUSAL & MORE GRINDING SURFACE. 3. CONVERGENCE OF MESIAL SIDE TOWARDS LINGUAL IS MORE VERY SLIGHT CONVERGENCE. 3 CUSP - CROWN WIDER LINGUALLY. 4. PRESENCE OF TWO CIRCULAR FOOSAE, TWO GROOVES( MESIAL & DISTAL) 2 CUSP- 2 CIRCULAR FOSSAE 3 CUSP-3 FOOSAE, & 3 GROOVES ( MESIAL, DISTAL & LINGUAL)

116. SOME TERMINLOGIES- RIDGE- is any linear elevation on the surface of a tooth & is named according to its location i.e buccal,incisal or marginal ridge FOSSA- it is an irregular depression or concavity. Eg central fossa are on the occlusal surface of molars, formed by the convergence of ridges terminating at a central point in the bottom of the depression where a junction of grooves occurs. SULCUS- it is a long depression or valley in the surface of a tooth between ridge or cusp GROOVE- it is a shallow linear depression on the surface of the tooth DEVELOPMENTAL GROOVE- it is a shallow groove or line between the primary part of the crown or root.

117. SUPPLEMENTAL GROOVES- it is less distinct & does not mark the junction of primary parts PITS- a small pinpoint depression located at the junction of developmental grooves or at terminals of those grooves

118. Maxillary First Molar It has a large crown with four well developed cusps and occasionally a small fifth cusp. In addition to the cusps it has three well formed roots; two buccal and one lingual.

119. Buccal aspect The crown is roughly trapezoidal two buccal cusp. Mesiobuccal & distobuccal cusp MB cusp is broader, as its mesial slope Meets its distal slope at an obtuse angle . DB cusp- its mesial slope meets the distal Slope at approx rite angles . Therefore the DB cusp is sharper. MB surface of crown is longer & wider than DB surface. Part of mesiopalatal and distopalatal cusps are seen from this aspect as the distopalatal line angle is obtuse The buccal developmental groove divides the two buccal cusps.this grooves mostly ends in a buccal pit .

120. Mesial outline of crown is straight, while distal outline is convex from this aspect. All 3 roots are visible from the buccal aspect. MB root curves distally, starting at the middle 3 rd. distal root is straighter. Point of bifurcation of the 2 buccal roots is approx at 4mm from the cervical line. Point of bifurcation of the palatal root is approx 3mm The common root base is k/a root trunk. 4mm

121. Lingual aspect General outline of lingual aspect is reverse of buccal aspect The mesiopalatal , distopalatal and fifth cusp are the only cusps seen from this aspect Mesiopalatal cusp is largest of all the cusps. Its MD width is about 3/5 th of the MD crown diameter. Its mesial & distal slopes meet at 90degree or so. Distopalatal cusp is small and spheroidal & smooth. The lingual developmental groove separates the lingual cusps 3/5th

122. Sometimes a fifth cusp called the cusp of carebelli may be present.When present it attached to the mesiopalatal surface of the mesiopalatal cusp. This morphological trait can take the form of a well developed fifth cusp, or it can grade down to a series of grooves, depressions, or pits on the mesial portion of the lingual surface. All 3 roots are visible,palatal root is the largest, with bluntly rounded apex.

123. Mesial aspect Mesiobuccal , mesiopalatal and fifth cusps are visible from this aspect also Mesial marginal ridge is placed Higher & is confluent with the mesiobuccal and mesiopalatal cusp ridges and is curved cervically The cervical line is irregular, curving occlusally Mesial aspect

124. Distal aspect Distobuccal and distopalatal cusps are seen The marginal ridge dips sharply cervically , exposing triangular ridges on the distal portion. The cervical line is almost straight. Concavity present on the distal Surface of the DB root,from the cervical line to the area of the root that is on a level with birfurcation separating the DB & lingual roots.

125. Occlusal aspect The occlusal aspect is roughly rhomboidal in shape. Acute angles- MB,DL obtuse angles-ML & DB. Lingual side of crown is slightly wider than the buccal side, & mesial side is wider than the distal side. Maxillary first molar crown is wider mesially than distally and wider lingually than buccally The triangular arrangement of 3 imp molar cusp is called as the MAXILLARY MOLAR PRIMARY CUSP TRIANGLE. The elevations and depression on this surface are: 1. Cusps Mesiopalatal cusp is the largest followed by mesiobuccal , distopalatal , distobuccal , and the smallest being the fifth cusp .

126. 2. Ridges Mesial marginal ridge and distal marginal ridge Oblique ridge( union of MP & DB cusp ridges) 3. Fossae Major fossae : central fossa (roughly triangular & mesial to the oblique ridge) and distal fossa (roughly linear & distal to the oblique ridge) Minor fossae : mesial triangular (immediately distal to the MMR) and distal triangular( immediately mesial to the DMR) 4 Grooves Central developmental groove Buccal developmental groove Lingual developmental groove

127. Fifth cusp groove 5. Pit Central developmental pit( from it the buccal development groove radiates bucally ) Transverse groove of the oblique ridge ( runs mesiodistally across the oblique ridge) Supplemental grooves

128. Root Maxillary first molar has three roots; two buccal and one palatal The palatal root is long and slender with bluntly round apex Mesiobuccal root is broader and curves distally while the distobuccal root is narrower at the base and a lot straighter

129. Both the buccal roots are of equal size but smaller than the palatal root The level of bifurcation area is more closer to the cervical area on the mesial side than on the distal side. 1.0 0 10.0 11.0 8.0 10.0 B L 12 13 7.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

130. Maxillary Second Molar The crown is shorter cervico-occlusally (0.5mm) and about the same width buccolingually when compared with maxillary first molar. The distobuccal cusp is not as well developed and the distolingual cusp is also small. The fifth cusp is absent The roots are almost the same size as that of the first molar. Roots are more inclined distally The apex of the lingual root is in line with the DL cusp tip instead of the lingual groove as was found on 1 st molar- buccal aspect.

131. Less prominent oblique ridge is present. Occlusal parallelogram is more twisted & is faciolinguallly more oblong, whereas the first molar is wider & squarish . Buccal groove is shorter & mostly without a buccal pit.

132. MAXILLARY 1 ST MOLAR MAXILLARY 2 ND MOLAR 1. CROWN IS LARGER CROWN IS SMALLER 2. OCCLUSAL OUTLINE IS ROUGHLY RHOMBOIDAL OCCLUSAL OUTLINE- MORE OBLONG, BECAUSE OF THE REDUCED MESIODISTAL DIMENSIONS 3. CUSP OF CARABELLI IS PRESENT CUSP OF CARABELLI IS ABSENT 4. PROMINENT OBLIQUE RIDGE LESS PROMINENT OBLIQUE RIDGE 5. DISTOPALATAL CUSP IS LARGER THAN DISTOBUCCAL CUSP BOTH DISTAL CUSPS ARE COMPARATIVELY SMALLER 6. OCCLUSAL TABLE IS WIDER & MORE SQUARISH OCCLUSAL PARALLELOGRAM IS MORE TWISTED 7. BUCCAL GROOVE LONGER & ENDING IN A BUCCAL PIT BUCCAL GROOVE SHORTER & WITHOUT A BUCCAL PIT. 8. LESS PROMINENT BUCCAL CERVICAL RIDGE MORE PROMINENT BUCCAL CERVICAL RIDGE

133. Mandibular Molars Mandibular molars are the biggest teeth in the mandibular arch. They have two broad roots for superior anchorage. The crown of lower molars are wider mesiodistally than buccolingually , the opposite is true of upper molars.

134. Mandibular First Molar It has five cusps ; two buccal, two lingual and one distal It has two roots; one mesial and one distal

135. Buccal aspect The crown is roughly trapezoidal from this aspect MB cusp is largest, widest & highest on buccal side DB cusp is slightly smaller, shorter & may be Sharper than the MB cusp. Distal cusp is present On the distobuccal angle of the crown. Two developmental grooves appear on this aspect; mesiobuccal (longer & deeper) and distobuccal developmental grooves. A cervical ridge is found near the cervical line. Point of bifurcation 3mm from the cervical line. Mesial root- curved mesially from the cervical portion to the middle 3 rd . & then curved distally upto the apex. Distal root- less curved, distally from cervical line till apex. 3mm

136. Lingual aspect Three cusps may be seen; two lingual and the lingual portion of the distal cusp The mesiolingual and distolingual cusps are pointed and have cusp ridges that are high enough to hide the buccal cusps The lingual developmental groove separates the lingual cusps The cervical line lingually is irregular. ML cusp is widest MD,with its cusp tip higher than the DL cusp. Mesial outline- convex, from cervical to the marginal ridge. Distal outline -straight from cervical line to a point immediately below the distal contact area. Roots appear 1mm longer lingually than bucally,coz the cusp ridges & cervical lines are at higher level. & MD dimension of the root trunk is less, therefore this slenderness makes roots appear longer. Root bifurcation is 4mm below the cervical line. 4mm

137. Mesial aspect Two cusps; mesiobuccal and distobuccal cusps, and one root; mesial root, are visible from this aspect Crown of mand . 1 st molar are slightly lingually tilted.Because of this they fit beneath & lingual to the maxillary Buccal cusps. Crown outline is roughly rhomboidal. The mesial aspect of the tooth is broader and the mesial cusps are higher hence the distal portion cannot be seen The mesial marginal ridge is confluent with the mesial ridges of the mesial cusps It is occlusally positioned hence triangular ridges not Visible.

138. The contact are is in near the junction of middle and occlusal third. Buccal outline CONVEX immediately above the cervical line. Lingual outline is STRAIGHT from cervical to the middle 3 rd . Cervical line slopes occlusally .

139. Distal aspect The gross outline is similar to the mesial aspect More of the tooth is seen from this aspect because the distal portion is smaller & distal sloping of occlusal surface. and the buccal and lingual surfaces converge distally DMR is short & made up of DCR of the distal cusp & DLCR of the DL cusp. Surface is CONVEX, & apical portion of the root appears to be more rounded. The cervical line is usually straight Distal root is more narrower BL than the mesial root.

140. Occlusal aspect The occlusal aspect is roughly hexagonal in shape The crown is wider mesiodistally than buccolingually The buccolingual measurement on the mesial portion is bigger than on the distal portion Two mesial cusp are larger than the two distal cusp. From a development point- all mandibular molars have 4 major cusps, while maxillary molars have 3 major cusps. 1 2 3 4

141. The elevations and depressions on this surface are: 1. Cusps Mesiobuccal cusp is the largest followed by the two lingual cusps, then the distobuccal , and the smallest being the distal cusp. 2. Ridges- Mesial marginal ridge and distal marginal ridge. Two transverse ridges are present formed by the TRIANGULAR RIDGES OF MB & ML CUSPS, & DB & DL CUSPS. 3. Fossae Major fossae : central fossa ( roughly circular, & placed centrally between the buccal & lingual cusp ridges) Minor fossae : mesial triangular(distal to MMR) and distal triangular fossae ( mesial to DMR)

142. 4. Grooves Central developmental groove Mesiobuccal developmental groove Distobuccal developmental groove Lingual developmental groove Supplemental grooves 5 Pit Central developmental pit Roots Mandibular first molar has two roots; mesial and distal roots The apical third of the both the roots tend to curve distally Both roots are wider buccally than they are lingually Deep developmental depression is found on the root trunk

143. 1.0 0 9.0 10.5 9.0 11.0 14.0 7.5 Curvature of Cervical Line M D Labiolingual Diameter at Cervical Line Labiolingual Diameter at Crest of Curvature Mesiodistal Diameter at Cervical Line Mesiodistal Diameter at Contact Area Root Length Crown Length Average Dimensions in millimeters

144. MANDIBULAR SECOND MOLAR Crown is wider mesiodistally than cervicoincisally or buccolingually 2 buccal cusps & 2 lingual cusps are present. MB cusp WIDER than DB CUSP. The tip of ML & DL cusp are visible from the buccal aspect. Only one buccal groove, separating the MB & DB CUSPS. Cervical line almost straight Mesiolingual cusp is longest & wider than the distolingual cusp. Both lingual cusps are pointed. Mesiodistal width at the cervix is greater than that of 1 st molar. Crown & root both converges lingually .

145. Occlusal aspect of Mandibular 2 nd molar The occlusal aspect of 2 nd molar differs considerably from the 1 st molar Shape is roughly rectangular. The distal cusp and distobuccal groove are absent The buccal and lingual grooves meet in the centre at right angles. The occlusal surface is roughened by numerous supplemental grooves

146. The elevations and depressions on this surface are: Cusps Mesiobuccal , distobuccal , mesiolingual and distolingual cusps Ridges Mesial marginal ridge and distal marginal ridge Fossae Major fossae : central fossa Minor fossae : mesial triangular and distal triangular fossae 4 Grooves Central developmental groove buccal developmental groove Lingual developmental groove Supplemental grooves 5 Pit Central developmental pit Occlusal aspect of Mandibular Second Molar

147. MANDIBULAR 1 ST MOLAR MANDIBULAR 2 ND MOLAR BUCCAL 1. MORE CONVERGENCE OF CROWN LESS CERVICAL CONVERGENCE OF CROWN . 2. TWO BUCCAL GROOVES ONLY ONE BUCCAL GROOVE 3. CONTACT AREA NOT LOCATED CERVICALLY MORE CERVICALLY LOCATED CONTACT AREA 4. LONGER ROOT TRUNK & CURVED ROOTS SHORTER ROOT TRUNKS & STRAIGHTER ROOTS 5. ROOTS ARE NOT CLOSER TOGETHER ROOTS ARE CLOSER TOGETHER

148. OCCLUSAL 1. CROWN OUTLINE ROUGHLY PENTAGON MORE RECTANGULAR OUTLINE 2. CROSS SHAPED GROOVE PATTERN NOT OBSERVED A CROSS SHAPED GROOVE PATTERN 3. CROWN TAPERS MORE FROM BUCCAL TO LINGUAL. CROWN TAPER FROM BUCCAL TO LINGUAL IS LESS 4. CENTRAL GROOVE IS ZIG-ZAG CENTRAL GROOVE IS STRAIGHT 5. LESS PROMINENT BUCCCAL CERVICAL RIDGE A MORE PROMINENT BUCCAL CERVICAL RIDGE

149. MAXILLARY MOLARS MANDIBULAR MOLARS 1. CUSPS MOSTLY FOUR, SOMETIMES THREE, ROOTS THREE (MB,DB,& PALATAL) CUSPS MAINLY FOUR, SOMETIMES FIVE & TWO ROOTS ( MESIAL & DISTAL) 2. CROWN WIDER FACIOLINGUALLY THAN MESIODISTALLY CROWN WIDER MESIODISTALLY THAN BUCCOLINGUALLY 3. LARGE & SMALL LINGUAL CUSP 2 NEARLY EQUAL SIZED LINGUAL CUSPS. 4. 1 ST MOLARS- WIDER ON LINGUAL THAN BUCCAL 1 ST MOLARS- TAPER FROM BUCCAL TO LINGUAL 5. ONE BUCCAL GROOVE PRESENT TWO BUCCAL GROOVES ARE PRESENT ON 1 ST MOLAR 6. OBLIQUE RIDGE IS PROMINENT NO OBLIQUE RIDGE, BUT HAS TWO TRANSVERSE RIDGES 7. FOUR FOSSA, INCLUDING LARGE DISTAL FOSSA THREE FOSSA (LARGE CENTRAL FOSSAE) 8. OCCLUSAL SURFACE- PARALLELOGRAM IN FOUR CUSP- RECTANGULAR IN 5 CUSP- PENTAGONAL 9. ROOT TRUNK SHORTER IN 1 ST MOLAR ROOT TRUNK LONGER 10. 3 ROOTS- MB, DB, PALATAL 2 ROOTS- MESIAL & DISTAL 11. ON VIEWING FROM PROXIMAL SIDE- CROWN ARE CENTERED ON ROOTS CROWN APPEARS TO BE SLIGHTLY LINGUALLY TILTED. 12. NEAR CERVIX CROWNS ARE NARROW CROWNS ARE NOT NARROW ON CERVIX.

150. REFERENCES- WOELFEL – D ental anatomy & its relevance to dentistry 5 th edition 2. WHEELERS- Dental anatomy, Physiology, & Occlusion 8 th edition 3.SATISH CHANDRA- Textbook of Dental & oral anatomy, physiology & occlusion.