Mesial

• When the mandibular first molar is viewed from the mesial aspect, with the specimen held with its mesial surface at right angles to the line of vision, two cusps and one root only are to be seen: the mesiobuccal and mesiolingual cusps and the mesial root
• The buccolingual measurement of the crown is greater at the mesial portion than it is at the distal portion.
• The buccolingual measurement of the mesial root is also greater than

  the same measurement of the distal root.

  Therefore, because the mesial portions of the tooth are broader and the mesial cusps are higher, the distal portions of the tooth cannot be seen from this angle.
• The crown from the mesial or distal aspect is roughly rhomboidal, and the entire crown has a lingual tilt in relation to the root axis.
• It should be remembered that the crowns of maxillary posterior teeth have the center of the occlusal surfaces between the cusps in line with the root axes
• difference between the outline form of the mandibular first molar and the mandibular second premolar from the mesial aspect. The first molar compares as follows:

  The crown is a fraction of a millimeter to 1 mm shorter in the first molar.
• difference between the outline form of the mandibular first molar and the mandibular second premolar from the mesial aspect. The first molar compares as follows:

  The root is usually that much shorter as well.
• difference between the outline form of the mandibular first molar and the mandibular second premolar from the mesial aspect. The first molar compares as follows:

  The buccolingual measurement of crown and root of the molar is greater by 2 mm or more.
• difference between the outline form of the mandibular first molar and the mandibular second premolar from the mesial aspect. The first molar compares as follows:

  The lingual cusp is longer than the buccal cusp. (The opposite is true of the second premolar.)
• Regardless of these differences, the two teeth have the same functional form except for the added reinforcement given to the molar lingually.
• Because of the added root width buccolingually, the buccal cusps of the first molar do not approach the center axis of the root as does the second premolar, and the lingual cusp tips are within the lingual outline of the roots instead of being on a line with them.
• From the mesial aspect, the buccal outline of the crown of the mandibular first molar is convex immediately above the cervical line.
• Before occlusal wear has shortened the buccal cusps, this curvature is over the cervical third of the crown buccally, outlining the buccal cervical ridge
• Buccal cervical ridge is more prominent on some first molars than on

  others. Just as on mandibular premolars, this ridge curvature does not exceed similar contours on other teeth as a rule when the mandibular first molar is posed in the position it assumes in the mandibular arch
• Above the buccal cervical ridge, the outline of the buccal contour may be slightly concave on some specimens or the outline may just be less convex or even rather flat as it continues occlusally outlining the contour of the mesiobuccal cusp.
• The mesiobuccal cusp is located directly above the buccal third of the mesial root.
• The lingual outline of the crown is straight in a lingual direction, starting at the cervical line and joining the lingual curvature at the middle third, the lingual curvature being pronounced between this point and the tip of the mesiolingual cusp.
• The crest of the lingual contour is located at the center of the middle third of the crown.
• The tip of the mesiolingual cusp is in a position directly above the lingual third of the mesial root.
• The mesial marginal ridge is confluent with the mesial ridges of the mesiobuccal and mesiolingual cusps. The marginal ridge is placed about 1 mm below the level of the cusp tips.