Maxillary First Molar Anatomy Quiz

Maxillary First Molar

• Deep developmental groove buccally on the root trunk starts at the bifurcation and progresses downward, becoming shallower until it terminates in a shallow depression at the cervical line
• Mesio-buccal and disto-buccal cusps dominate the facial outline
• Mesio-buccal is wider than disto-buccal
• Buccal developmental groove separates MB and DB cusps and terminates halfway the crown height in the BUCCAL PIT
• Mesio-lingual cusp is the largest
• Disto-lingual cusp is also visible
• All three roots are visible.
• The bifurcation between the MB and DB roots starts at the end of the root trunk on the junction between Cervical and middle thirds.
• Mesio-Buccal root has a curvature and might have two canals.
• Two cusps of unequal size separated by the lingual developmental groove, which is continuous with the distolingual (or distal oblique) groove.
• The larger mesiolingual cusp often displays the Carabelli trait.
• ML cusp makes 3/5s of MD width of the crown
• ML cusp is prominent and blunt
• DL cusp rounded, shorter and narrower
• L groove separates L cusps and terminates midway of L surface
• Only 2 lingual cusps are seen
• Buccal Cusps not seen
• Disto-lingual groove separates the 2 cups
• Cusp of Carabelli is seen
• The 3 roots are visible
• Proximal outline of B roots
• L root is tapered with a blunt apex
• L root apex is in line with crown midline
• Mesio-palatal cusp, mesial marginal ridge, and mesiobuccal cusp are seen
• Cusp of Carabelli is seen in this view
• Maximum BP dimension at the middle of cervical third
• MP is higher than MB cusp
• B cervical 1/3 is strongly convex
• B outline continues in a straight line
• Palatal outline is uniformly convex
• Palatal HOC is at the midpoint
• CL is slightly convex occlusally
• Trapezoidal outline with maximum bucco-palatal dimension is at the cervix of the crown
• Buccal Maximum curvature: middle of cervical 3rd, then outline continues straight
• Palatal maximum curvature: middle of middle 3rd
• Palatal root is narrow and Banana-shaped, it curves palatally then buccally at the apex
• Mesial contact area placed more to the buccal
• Mesial marginal ridge side is marked by several tubercles and supplementary grooves
• Cervical line is slightly curved towards the Occlusal
• Deep developmental groove on the root surface on the mesio-buccal root
• MB & P roots
• MB root is broad BL
• P root is narrow and Banana-shaped
• Both MB & P roots project beyond crown profile
• The two distal cusps are clearly seen.
• The distal marginal ridge is somewhat shorter than the mesial one.
• DB cusp is more prominent than DP
• Only small portions of M cusps are visible
• Distal MR is shorter and less prominent than M
• Distal MR rarely has tubercles
• B & P profiles are similar to those of M aspect
• CL is nearly straight
• Cervical line is straight
• Disto buccal root is shortest
• No Cusp of Carbelli or groove present

Maxillary First Molar Occlusal View

• The tooth outline is somewhat rhomboidal with four distinct cusps.
• The cusp order according to size is: mesiolingual, mesiobuccal, distobuccal, and distolingual.
• A frequent feature of maxillary molars is the Cusp of Carabelli located on the mesio paltal cusp.
• MB & DL angles are acute
• ML & DB angles are obtuse
• 1/3 of B surface & ½ of L are visible
• B outline: D part is more L than M part
• Two distinct components:
  • Trigon:
    • MB, ML & DB cusps
    • Tricuspate triangle
  • Talon:
    • DL cusp & D MR
    • Located DL to the tricuspate triangle
    • Well-developed in 1st molar and undergoes reduction in size in 2nd and 3rd molars

Maxillary First Molar Occlusal Surface

• Mesial and distal triangular fossae
• M triangular fossa
• M pit
• Mesial marginal ridge is longer and more prominent than the Distal marginal ridge
• MB & ML supplementary grooves
• D triangular fossa (minor fossa)
• Distal pit
• Oblique ridge
• DB & DL supplementary grooves
• Two Major Fossae:
  • Central fossa
  • Central pit
  • Buccal groove
  • Distal groove
  • Central groove
  • Distal fossa
  • D pit
  • DL groove or distal oblique which continues as the L groove

Maxillary Second Molar

• Similar to maxillary first molar generally but differ in the followings:

  • The disto-buccal cusp is not as well developed as in maxillary first molar.
  • The disto palatal cusp is smaller.
  • The cusp of Carabelli is absent from this tooth.
  • The roots are of the same length as 1st molar and sometimes longer
  • The roots are slightly less divergent
  • The crown is shorter cervico-occlusally with almost the same width bucco-palatally when compared to maxillary first molar

• The crown is shorter occluso-cervically and narrower mesiodistally when compared to the first molar.

• The distobuccal cusp is smaller than the mesiobuccal cusp.

• The roots are more parallel; the apex of the mesial root is on line with the buccal developmental groove.

• Mesial and distal roots tend to be about the same length.

• Less prominent DB cusp and narrower MD

• Distally inclined B roots

• The two buccal roots are nearly parallel, and they are more straight compared to 1st molar.

• Both Mesial and Distal contact points tend to be centred bucco-palatally below the marginal ridges.

• DP cusp is smaller in width and height

• Palatal root is narrower MD and slightly D inclined

• No cusp of Carabelli

• The crown is shorter than the first molar

• The palatal and MB roots have less divergence.

• The roots tend to remain within the crown profile.

• Less numerous MR tubercles

• Roots tend to remain within the crown profile.

• Buccal Maximum curvature: middle of cervical 3rd

• Palatal maximum curvature: middle of middle 3rd

• Smaller D cusps

• A greater portion of the occlusal aspect is visible

• The distolingual cusp is smaller on the second than on the first molar.

• When it is much reduced in size, the crown outline is described as 'heart-shaped.'

• Cusp of Carabelli is usually absent.

• The order of cusp size, largest to smallest, is the same as the first but is more exaggerated: mesiolingual, mesiobuccal, distobuccal, and distolingual.

• MB and DL angles are more acute

• ML and DB angles are more obtuse

• Talon is more reduced in size

• More variable pit/groove pattern

• More numerous supplementary groove

• Crown is more constricted MD

• narrower crown mesiodistally when compared to the first molar

• The disto-palatal cusp is smaller in the 2nd molar (smaller talon).

• Difference in the size of cusps is more exaggerated: Largest to smallest: mesiopalatal, mesiobuccal, distobuccal, and distopalatal.

Maxillary Third Molar

• Maxillary third molars vary considerably in size shape and position

• Some third molars resemble the adjacent second molar; others may have many cusps, small 'cusplets', and many grooves.

• The crown of this tooth is the smallest of the maxillary molars

• The crown is usually shorter in both axial and mesiodistal dimensions.

• Two buccal roots are present, but in most cases, they are fused.

• The mesiobuccal cusp is larger than the disto buccal cusp.

• Crown is smallest in all dimensions

• Roots are much short, and commonly fused

• Roots shows a pronounced distal inclination

• The crown:

  • Shorter and smaller in all dimensions.
  • The mesio-buccal cusp is larger than the disto-buccal cusp.

• Roots shows a slight distal inclination.

• Mesial contact point middle of crown is below the marginal ridges.

• Technically, the mesial surface is the only 'proximal' surface.

• The distal surface does not contact another tooth.

• In most third molars, there is just one large lingual cusp (DL cusp is usually missing).

• In some cases, there is a poorly developed distolingual cusp and a lingual groove.

• The lingual root is often fused to the two buccal roots.

• The outline of the crown is rounded;

• Crown profile is irregular

• Fused roots

• DL cusp is usually absent

• More of the occlusal surface is visible compared with 1st and 2nd

• The outline of the occlusal surface can be described as triangular or 'heart-shaped.'

• Difference in the size of cusps is even more exaggerated: Largest to smallest: mesiopalatal, mesiobuccal and distobuccal distopalatal is of minimal size.

• Oblique ridge is barely visible

• Pit/groove pattern is variable

• Numerous supplementary grooves