Primary Maxillary Second Molar

The primary maxillary second molar is similar in characteristic to the permanent maxillary first molar, but, is smaller.

Buccal Aspect

Crown is much larger than the primary first molar.
Shows two well-defined buccal cusps (nearly equal in size), with a buccal developmental groove between them.
Crown is narrow at the cervix in comparison to MD measurement at the contact areas.

Lingual Aspect

Shows three cusps: two well developed mesiolingual and distolingual cusps, and a third poorly developed supplemental cusp known as Tubercle of Carabelli, or the fifth cusp.
- It lies apical to the ML cusp and acts as a buttress or supplement to the bulk of the ML cusp.
- If the fifth cusp is missing, some traces of developmental lines or dimples remain.
The ML and DL cusps are separated by a well-defined developmental groove, which connects with the developmental groove outlining the fifth cusp.

Mesial Aspect

Crown has typical molar outline, resembling permanent molars.
Crown appears short as its buccolingual width is shorter in comparison to its length.
Mesiolingual cusp with its fifth cusp appears large in comparison to the mesiobuccal cusp.
Mesiobuccal cusp appears relatively short and sharp, and is directly below the bifurcation of MB and lingual root.

Distal Aspect

The distal measurement of the crown is less than the mesial measurement.
The lingual outline is smooth and rounded, while, the buccal surface is almost straight from the crest of curvature to the tip of the buccal cusp.
Distobuccal and distolingual cusps are about the same length.
Cervical line is approximately straight, as found mesially.

Occlusal Aspect

The tooth resembles permanent maxillary first molar.
Shape is somewhat rhomboidal, with four well-developed cusps and one supplemental cusp.
Buccal surface is flat with developmental groove between the cusps (less prominent compared to permanent first molar).
Occlusal surface has a central fossa with a central pit, well defined mesial triangular fossa, distal to the mesial marginal ridge with a mesial pit at its center.
Central groove is well-defined, present at the bottom of a sulcus, connecting mesial triangular fossa with the central fossa.
Buccal developmental groove extends buccally from the central pit, separating the triangular ridges (occlusal continuations of MB and DB cusps).
Oblique ridge is prominent and connects the ML cusp with the DB cusp.
Distal fossa lies distal to the oblique ridge and harbors the distal developmental groove.
Distal groove acts a line of demarcation between the ML and DL cusps, and continues on to the lingual surface as lingual developmental groove.
Distal marginal ridge is as well developed as the mesial marginal ridge. (Marginal ridges are not developed equally in the primary maxillary first molars.)

Occlusal surface of primary upper second molar

Buccal Aspect

Root appears slender.
Longer and heavier than the roots of primary first molar.
Point of bifurcation between the buccal roots is close to the cervical line of the crown.

Lingual Aspect

All three roots can be seen.
Lingual root is large and thick compared to other two roots, however, it is approximately the same length as the MB root.

Mesial Aspect

Mesiobuccal root appears broad and flat, and extends lingually far out beyond the crown outline.
Lingual root have somewhat similar curvature as lingual root of primary maxillary first molar.
Point of bifurcation between MB and lingual root is 2-3 mm apical to the cervical line.

Distal Aspect

All three are seen, although the distobuccal root is superimposed on the mesiobuccal root.
Distobuccal root is shorter and narrower than the other roots.
Point of bifurcation between DB and lingual root is more apical than any other points of bifurcation, and is nearly centered above the crown.

Wheeler's Dental Anatomy, Physiology and Occlusion(2019), Stanley J. Nelson DDS MS, Elsevier.

*This article is excerpt from the above mentioned book and Medical Sutras does not make any ownership and affiliation claims.