dental anatomy & physiology of permanent teeth
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dental anatomy & physiology of permanent teeth

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includes the dental anatomy of all permanent teeth, contacts, contours, fissures, grooves, embrasure,fossa

includes the dental anatomy of all permanent teeth, contacts, contours, fissures, grooves, embrasure,fossa

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dental anatomy & physiology of permanent teeth dental anatomy & physiology of permanent teeth Presentation Transcript

  • DENTAL ANATOMY & PHYSIOLOGY OF TEETH
  • 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.
  • 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 3rd, & lingual contour at the middle 3rd) • Curvature of the Cemento-enamel junction ( curvature of cervical lines on the mesial & distal surfaces)
  • 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
  • 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.
  • 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.
  • CONTACTS are OBSERVED from 2 views• Labial /buccal aspectdemonstrates the cervicoincisal/cervico -occlusal position • Incisal /occlusal aspectdemonstrates the facio-lingual position
  • • 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
  • Proximal Contacts Maxillary Mesial Distal Central incisor Incisal 1/3 Lateral incisor 1st pre 2nd pre Junc of incisal/middle 1/3 Junc of incisal/middle 1/3 Middle 1/3 Middle 1/3 Junc of incisal/middle 1/3 Middle 1/3 1st molar 2nd molar 3rd molar Middle 1/3 Middle 1/3 Middle 1/3 Canine Middle 1/3 Middle 1/3 Middle 1/3 Middle 1/3 Middle 1/3 n/a
  • 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 1st pre Middle 1/3 Middle 1/3 2nd pre Middle 1/3 Middle 1/3 1st molar Middle 1/3 Middle 1/3 2nd molar Middle 1/3 Middle 1/3 3rd molar Middle 1/3 n/a
  • 1. Contact area move cervically from anterior to posterior in each quadrant 2. On individual teeth the distal contact is more cervically located then the mesial contact 3. Contacts increase in size from anterior to posterior 2 **Note: Contacts on incisors in incisal1/3, Where as contacts on molars in middle /3
  • Contacts • Mandibular Teeth: Contact their class counterpart and the tooth mesial • Maxillary Teeth: Contact their class counterpart and the tooth distal
  • 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
  • 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
  • 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
  • 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
  • • 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
  • 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.
  • 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 Buccal Lingual
  • Buccal Lingual The height of contour on both the facial and lingual surfaces of anterior teeth is located in the cervical third.
  • • The height of contour of the buccal surfaces of posterior teeth is located in the gingival third Lingual Buccal • 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.
  • Height of Contours Maxillary Facial Lingual Central incisor Lateral incisor Canine 1st pre Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Middle 1/3 2nd pre 1st molar 2nd molar 3rd molar Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Middle 1/3 Middle 1/3 Middle 1/3 Middle 1/3
  • Height of Contours Mandibular Facial Lingual Central incisor Lateral incisor Canine 1st pre Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Middle 1/3 2nd pre 1st molar 2nd molar 3rd molar Cervical 1/3 Cervical 1/3 Cervical 1/3 Cervical 1/3 Middle 1/3 Middle 1/3 Middle 1/3 Middle 1/3
  • • 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.
  • 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.
  • • 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
  • 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
  • LMAXILLARY CENTRAL INCISORabial • 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. Distal margin shorter & rounded Mesial margin straight & meets at 90 degree Distoincisal angle more rounded, making an obtuse angle Mesioincisal angle rounded, making somewht 90 degrees
  •   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 3rd. Convexity in cervical third a b
  • 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 Cingulum Lingual fossa Marginal ridges Lingual ridge
  •   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 Labial aspect Lingual aspect
  • 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 Convex near cingulum Labial margin convex Concave in the middle
  •   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
  • 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 3rd, this is because the distoincisal angle is slightly lingually positioned than mesioincisal angle. Distal aspect
  • 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. Bilaterally symmetrical Incisal ridge
  • Root The root is straight and tapers from the cervical line to the apex giving it a conical Straight conical blunt root shape The root ends in a blunt apex. Root : crown ratio is 1.3:1.05 Average Dimensions in millimeters Crown Length Root Length 10.5 13.0 Mesiodistal Diameter of crown 8.5 Mesiodistal Diameter at Cervical Line 7.0 Labiolingual Diameter at Crest of Curvature 7.0 Labiolingual Diameter at Cervical Line 6.0 Curvature of Cervical Line M D 3.5 2.5
  • Maxillary Lateral Incisor  The general shape is similar to maxillary central incisors except that they are shorter and narrower. Maxillary central incisor bigger and lateral incisor smaller  Next to third molars maxillary lateral incisors are the teeth that show most variation in crown size, shape and form
  •  The mesioincisal and distoincisal angles are more rounded than the corresponding angles of the maxillary central incisor Maxillary Lateral Incisor Distoincisal angle more rounded Maxillary Central Incisor Mesioincisal angle more rounded Distoincisal angle Mesioincisal angle
  •  On the lingual aspect the marginal ridges and cingulum are more prominent Prominent marginal ridges Prominent cingulum
  • MAXILLARY CENTRAL INCISOR MAXILLARY LATERAL INCISOR 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 3rd DISTAL CONTACT AREA AT JUNC OF INCISAL & MIDDLE 3rd. LABIAL VIEW
  • 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
  • PROXIMAL VIEW 1. CERVICAL LINE CURVATURES ARE MORE CURVATURE IS LESS 2. ROOT IS EVENLY TAPERED ROOT IS MORE CONVEX
  • 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
  • MANDIBULAR INCISOR Mandibular central incisor and lateral are similar in anatomy and complement each other in function. Labial 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
  •   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
  • 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.
  • Mesial aspect    Crown is wedge shaped, with the 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 3rd of mesial root surfaces. Labial surface inclined lingually
  •   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
  • Distalaspect • Distal surface is very similar to the mesial surface. • The cervical line is less curved. Distal aspect
  • 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. Labiolingually bigger than mesiodistally Bilaterally symmetrical • The labiolingual diameter is greater than mesiodistal diameter. • Newly erupted teeth show mamelons which wear off Mamelons upon mastication
  • 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 Average Dimensions in millimeters Crown Length Root Length 9.5 12.5 Mesiodistal Diameter at Contact Area 5.0 Mesiodistal Diameter at Cervical Line 3.5 Labiolingual Diameter at Crest of Curvature 6.0 Labiolingual Diameter at Cervical Line 5.3 Curvature of Cervical Line M D 3.0 2.0
  • 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.
  •  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 Fan shaped appearance Cervical portion narrower
  •   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 Average Dimensions in millimeters Crown Length 9.5 Root Length 14.0 Mesiodistal Diameter at Contact Area 5.5 Mesiodistal Diameter at Cervical Line 4.0 Labiolingual Diameter at Crest of Curvature 6.5 Labiolingual Diameter at Cervical Line 5.8 Curvature of Cervical Line M D 3.0 2.0
  • 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
  • MAXILLARY INCISORS MANDIBULAR INCISORS LABIAL 1. CROWN MESIODISTALLY WIDER & LESS CROWN IS LONG, NARROW & MORE SYMMETRICAL SYMMETRICAL 2. DISTOINCISAL ANGLES MORE ROUNDED MESIOINCISAL SHARP, & DISTOINCISAL ANGLES ARE SLIGHTLY ROUNDED 3. SHALLOW LABIAL DEPRESSIONS ARE COMMONLY PRESENT NOT PRESENT 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 1. CINGULUM IS PROMINENT VERY SMALL CINGULUM 2. INCISAL EDGE LABIAL TO ROOT AXIS INCISAL EDGE LINGUAL TO ROOT AXIS LINGUAL PROXIMAL
  • 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 3rd.
  • 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)
  • 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.
  • Labial ridge Distal cusp ridge Cusp tip Labial aspect Mesial Cusp Ridge
  • 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
  • Cingulum Mesial lingual fossa Distal marginal ridge Mesial marginal ridge Distal lingual fossa Lingual ridge Lingual aspect
  • 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 3rd & again slight convex in the incisal 3rd.
  • Mesial aspect
  • 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
  • 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
  • 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. Average Dimensions in millimeters Crown Length Root Length 10.0 17.0 Mesiodistal Diameter at Contact Area 7.5 Mesiodistal Diameter at Cervical Line 5.5 Labiolingual Diameter at Crest of Curvature 8.0 Labiolingual Diameter at Cervical Line 7.0 Curvature of Cervical Line M D 2.5 1.5
  • 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   
  • 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.
  • 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 Average Dimensions in millimeters Crown Length Root Length 11.o 16.0 Mesiodistal Diameter at Contact Area 7.0 Mesiodistal Diameter at Cervical Line 5.5 Labiolingual Diameter at Crest of Curvature 7.5 Labiolingual Diameter at Cervical Line 7.0 Curvature of Cervical Line M D 2.5 1.0
  • MAXILLARY CANINE MANDIBULAR CANINE 1. APICAL ROOT TIP IS DISTALLY BENT CROWN IS SLIGHTLY TIPPED DISTALLY ON ROOT 2. 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 LABIAL 3. 4. 5. 120 degree 105 degree
  • 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
  • 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
  • INCISAL 1. 2. CROWN IS ASYMMETRICAL, WITH DISTAL HALF IS SLIGHTLY THICKER. MORE BUCCOLINGUAL BULK IN MESIAL HALF, DISTAL HALF IS THINNER. LESS DISTLINGUAL CROWN TWIST 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
  • 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.
  • 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 3rd, shows development depressions k/a mesiobuccal & distobuccal development depressions. 
  • 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
  • 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. 
  • Mesial aspect From this aspect crown appears roughly TRAPEZOIDAL, with longest uneven arm Towards the cervical 3rd, while shortest Arm at occlusal 3rd.  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. 
  •   Lingual outline from cervical 3rd 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. •
  • 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 3rd.
  • 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
  • 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 grooveRuns mesiodistally with pits at both ends. The length of central groove is more than one third of the mesiodistal width of occlusal surface.
  • Mesial marginal developmental Grooveit 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 2nd 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. •
  • 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.
  • Average Dimensions in millimeters Crown Length Root Length 8.5 14.0 Mesiodistal Diameter at Contact Area 7.0 Mesiodistal Diameter at Cervical Line 5.0 Labiolingual Diameter at Crest of Curvature 9.0 Labiolingual Diameter at Cervical Line 8.0 Curvature of Cervical Line M D 1.0 0
  • Maxillary 2nd 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 1st 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. 
  • 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 1st premolar 
  • 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 
  • • Root  Maxillary 2nd premolar has one root, which is usually as long or a millimeter longer than the root of maxillary 1st premolar Average Dimensions in millimeters Crown Length Root Length 8.5 14.0 Mesiodistal Diameter at Contact Area 7.0 Mesiodistal Diameter at Cervical Line 5.0 Labiolingual Diameter at Crest of Curvature 9.0 Labiolingual Diameter at Cervical Line 8.0 Curvature of Cervical Line M D 1.0 0
  • MAXILLARY 1ST PREMOLAR MAXILLARY 2ND PREMOLAR 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 BUCCAL
  • 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
  • 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
  • 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 CUSP INCLINES ALMOST LINGUAL EQUAL TO BUCCAL
  • 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 LESS COMMON, PRESENT IN ONLY 37% OF IN 97% OF CASES CASES 10 MESIOBUCCAL CUSP RIDGE & MARGINAL . RIDGE MEETS AT RIGHT ANGLE MESIOBUCCAL CUSP RIDGE & MARGINAL RIDGE MEETS AT OBTUSE
  • Mandibular First Premolar
  • 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.
  • 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. 
  • • 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.
  • 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
  • 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 3rd, then tapers apically to end in a pointed apex, situated in line with buccal cusp tip. •
  • 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.
  • 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.
  • • 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.
  • 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.
  • Average Dimensions in millimeters Crown Length Root Length 8.5 14.0 Mesiodistal Diameter at Contact Area 7.0 Mesiodistal Diameter at Cervical Line 5.0 Labiolingual Diameter at Crest of Curvature 7.5 Labiolingual Diameter at Cervical Line 6.5 Curvature of Cervical Line M D 1.0 0
  • 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
  • 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 
  • 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 
  • 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 
  • 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 2nd premolar has a single root which is larger and longer than the root of mandibular 1st premolar The root is usually wide with a blunt apex
  • MANDIBULAR 1ST PREMOLAR MANDIBULAR 2ND PREMOLAR 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 BUCCAL 110 DEGREE 130 DEGREE
  • 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
  • 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 & MESIAL MARGINAL RIDGE IS HIGH & IS IN PARALLEL TO TRIANGULAR RIDGE OF BUCCAL HORIZONTAL PLANE, HENCE ONLY LITTLE CUSP, HENCE MUCH OF OCCLUSAL SURFACE OCCLUSAL SURFACE IS VISIBLE IS VISIBLE 4. ROOTS HAVE DEEP LONGITUDINAL DEPRESSIONS NO DEPRESSIONS PRESENT.
  • 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)
  • 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.
  • • 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
  • 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.
  • 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.
  • • 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 3rd. distal root is straighter. • Point of bifurcation of the 2 4mm 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.
  • 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 3/5th 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
  • • 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.
  • 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
  • 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.
  • Occlusal aspect • • • • • 1. 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: Cusps • Mesiopalatal cusp is the largest followed by mesiobuccal, distopalatal, distobuccal, and the smallest being the fifth cusp.
  • 2. 3. 4 Ridges  Mesial marginal ridge and distal marginal ridge  Oblique ridge( union of MP & DB cusp ridges) 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) Grooves  Central developmental groove  Buccal developmental groove  Lingual developmental groove
  •   Fifth cusp groove Pit  Central developmental pit( from it the buccal development groove radiates bucally)  5. Transverse groove of the oblique ridge ( runs mesiodistally across the oblique ridge) Supplemental grooves
  • 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
  • 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. Average Dimensions in millimeters Crown Length 7.5 Root Length B L 12 13 Mesiodistal Diameter at Contact Area Mesiodistal Diameter at Cervical Line 10.0 8.0 Labiolingual Diameter at Crest of Curvature 11.0 Labiolingual Diameter at Cervical Line 10.0 Curvature of Cervical Line M D 1.0 0
  • 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 1st molar- buccal aspect.
  • • 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.
  • MAXILLARY 1ST MOLAR MAXILLARY 2ND 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
  • 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.
  • Mandibular First Molar It has five cusps ; two buccal, two lingual and one distal It has two roots; one mesial and one distal
  • 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. 3mm • 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 3rd. & then curved distally upto the apex. • Distal root- less curved, distally from cervical line till apex.
  • 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 4mm 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.
  • Mesial aspect Two cusps; mesiobuccal and distobuccal cusps, and one root; mesial root, are visible from this aspect • Crown of mand. 1st 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.
  • • 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 3rd. • Cervical line slopes occlusally.
  • 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.
  • 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. • • 2 4 3 1
  •  1. 2. 3. The elevations and depressions on this surface are: Cusps  Mesiobuccal cusp is the largest followed by the two lingual cusps, then the distobuccal, and the smallest being the distal cusp. 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. 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)
  • 4. 5 Grooves  Central developmental groove  Mesiobuccal developmental groove  Distobuccal developmental groove  Lingual developmental groove  Supplemental grooves 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
  • Average Dimensions in millimeters Crown Length Root Length 7.5 14.0 Mesiodistal Diameter at Contact Area 11.0 Mesiodistal Diameter at Cervical Line 9.0 Labiolingual Diameter at Crest of Curvature 10.5 Labiolingual Diameter at Cervical Line 9.0 Curvature of Cervical Line M D 1.0 0
  • 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 1st molar. • Crown & root both converges lingually.
  • Occlusal aspect of Mandibular 2nd molar  The occlusal aspect of 2nd molar differs considerably from the 1st 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
  • The elevations and depressions on this surface are: 1. Cusps  Mesiobuccal, distobuccal, mesiolingual and distolingual cusps 2. Ridges  Mesial marginal ridge and distal marginal ridge 3. 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
  • MANDIBULAR 1ST MOLAR MANDIBULAR 2ND MOLAR 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 BUCCAL
  • 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 CROWN TAPER FROM BUCCAL TO LINGUAL 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
  • 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. 1ST MOLARS- WIDER ON LINGUAL THAN BUCCAL 1ST MOLARS- TAPER FROM BUCCAL TO LINGUAL 5. ONE BUCCAL GROOVE PRESENT TWO BUCCAL GROOVES ARE PRESENT ON 1ST 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 1ST MOLAR ROOT TRUNK LONGER 10. 3 ROOTS- MB, DB, PALATAL 2 ROOTS- MESIAL & DISTAL 11. ON VIEWING FROM PROXIMAL SIDECROWN ARE CENTERED ON ROOTS CROWN APPEARS TO BE SLIGHTLY LINGUALLY TILTED. 12. NEAR CERVIX CROWNS ARE NARROW CROWNS ARE NOT NARROW ON CERVIX.
  • REFERENCES1. WOELFEL – Dental anatomy & its relevance to dentistry 5th edition 2. WHEELERS- Dental anatomy, Physiology, & Occlusion 8th edition 3.SATISH CHANDRA- Textbook of Dental & oral anatomy, physiology & occlusion.