Mandibular Premolars

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A brief anatomy of Mandibular Premolars

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Mandibular Premolars

  1. 2. Dr.Syed Sadatullah King Khalid University Abha
  2. 3. <ul><li>Buccal aspect </li></ul><ul><li>From the buccal aspect a large well formed, pointed buccal cusp is seen </li></ul><ul><li>The mesial outline is similar to the distal outline </li></ul><ul><li>The mesiobuccal cusp ridge is shorter than the distobuccal cusp ridge (similar to canines) </li></ul><ul><li>The mesial and distal slope of the buccal cusp sometimes show concavity </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  3. 4. Dr.Syed Sadatullah King Khalid University Abha Buccal aspect
  4. 5. <ul><li>Lingual aspect </li></ul><ul><li>The crown tapers and inclines lingually </li></ul><ul><li>The lingual cusp is small, pointed and nonfunctional and in some specimens it is no longer than the cingulum of maxillary canine </li></ul><ul><li>Between the mesiobuccal and lingual lobe is the mesiolingual developmental groove </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  5. 6. Dr.Syed Sadatullah King Khalid University Abha Lingual aspect
  6. 7. <ul><li>Mesial aspect </li></ul><ul><li>The lingual inclination of the crown can be seen from this aspect </li></ul><ul><li>The lingual cusp is approximately two thirds the size of the buccal cusp </li></ul><ul><li>The mesial marginal ridge has extreme lingual slope </li></ul><ul><li>Mesiolingual developmental groove is present between the mesial marginal ridge and the mesiolingual cusp ridge </li></ul><ul><li>The mesial and distal contact areas are in the middle third, the distal contact area being more wider. </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  7. 8. Dr.Syed Sadatullah King Khalid University Abha Mesial aspect
  8. 9. <ul><li>Distal aspect </li></ul><ul><li>. Distal marginal ridge is higher and does not have the extreme lingual slope </li></ul><ul><li>The cervical line curvature is less curved </li></ul>Dr.Syed Sadatullah King Khalid University Abha Distal aspect
  9. 10. <ul><li>Occlusal aspect </li></ul><ul><li>The crown converges sharply to the centre of the lingual surface </li></ul><ul><li>The occlusal surface has two depressions; mesial and distal fossae </li></ul><ul><li>Most common form of mandibular 1st premolar shows a mesiolingual depression and mesiolingual developmental groove </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  10. 11. Dr.Syed Sadatullah King Khalid University Abha Occlusal aspect
  11. 12. <ul><li>Root </li></ul><ul><li>The mandibular 1st premolar has one root </li></ul><ul><li>The root is approximately (3-4mm)shorter than the root of mandibular canine but the outline bears a close resemblance to the canine </li></ul><ul><li>A deep developmental groove is seen on the mesial aspect on the root </li></ul><ul><li>On the distal aspect there is a shallow depression devoid of any developmental groove. </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  12. 13. Dr.Syed Sadatullah King Khalid University Abha 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
  13. 14. Dr.Syed Sadatullah King Khalid University Abha <ul><li>Mandibular Second Premolar </li></ul><ul><li>Mandibular 2nd premolar resembles the mandibular 1st premolar from the buccal aspect only </li></ul><ul><li>The crown assumes two common types. The first and more common type is the 3-cusp type and the second is the 2-cusp type </li></ul><ul><li>The two differ mainly in the occlusal design </li></ul>
  14. 15. <ul><li>Buccal aspect </li></ul><ul><li>The buccal cusp is shorter with the cusp slopes presenting less degree of angulations </li></ul><ul><li>Lingual aspect </li></ul><ul><li>There may be one or two lingual cusps – mesiolingual and distolingual cusps </li></ul><ul><li>The cusp(s) are more developed than the lingual cusp of lower first premolar </li></ul><ul><li>A groove separates the two lingual cusps </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  15. 16. Dr.Syed Sadatullah Ibnsina National Medical College <ul><li>Mesial and Distal aspects </li></ul><ul><li>The crown and root are wider buccolingually </li></ul><ul><li>Unlike mandibular 1st premolar the marginal ridge is at right angle to the long axis of the tooth </li></ul><ul><li>More of occlusal surface is visible form the distal aspect because the distal marginal ridge is at lower level than the mesial marginal ridge </li></ul><ul><li>The contact areas both mesial and distal are broad and appear higher because of the short buccal cusp </li></ul>
  16. 17. <ul><li>Occlusal aspect </li></ul><ul><li>From the occlusal aspect the 3-cusp type appears square and the 2-cusp type appears rounded. </li></ul><ul><li>3-cusp type: </li></ul><ul><li>- each cusp is separated by deep developmental grooves forming a “Y” shape in the centre </li></ul><ul><li>- the occlusal surface also includes </li></ul><ul><li>a. central pit </li></ul><ul><li>b. mesial developmental groove </li></ul><ul><li>c. mesial triangular fossa </li></ul><ul><li>d. distal developmental groove </li></ul><ul><li>e. distal triangular fossa </li></ul><ul><li>f. lingual developmental groove </li></ul><ul><li>g. supplemental grooves </li></ul>Dr.Syed Sadatullah King Khalid University Abha
  17. 18. Dr.Syed Sadatullah Ibnsina National Medical College <ul><li>2-cusp type: </li></ul><ul><li>- one buccal cusp and one well developed lingual cusp is present </li></ul><ul><li>- a central groove travels in a mesiodistal direction </li></ul><ul><li>and end in mesial and distal fossa (forming ‘H’ shape) </li></ul><ul><li>Root </li></ul><ul><li>Mandibular 2 nd premolar has a single root which is larger and longer than the root of mandibular 1 st premolar </li></ul><ul><li>The root is usually wide with a blunt apex </li></ul>
  18. 19. Dr.Syed Sadatullah King Khalid University Abha Buccal aspect Lingual aspect Mesial aspect Distal aspect Occlusal aspect Mandibular Second Premolar

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