Characteristics of the Upper Fourth Molar

Crown: Ovoid or square shaped.

Cusps: Slightly rounded, slightly inclined distally.

Mesial and Distal Marginal Ridges: Inclined 30 degrees, forming prominent shoulders along the buccal contours.

Mesial Fossa: Located in the mesial cervical third, slightly depressed in the middle of the crown.

Lobes and Sulci: Three lobes with two shallow sulci.

Root: Conical, converging into a blunt apex.

Lingual Surface: Smaller than the buccal surface, with the buccal outline visible.

Lingual Cusp: Inclined mesially.

Prominences, Ridges, Depressions: No prominences, ridges, or depressions.

Two Lingual Halves: Symmetrical.

Root Apices: Two root apices visible.

Mesial Fossa: Runs along most of the root length.

Buccal Cusp: Viewed from the mesial aspect, the buccal cusp is taller than the lingual cusp.

Mesial Marginal Ridge: Separated by the mesial marginal groove.

Cervical Third of Mesial Surface: Has a mesial fossa.

Root: One buccal root and one lingual root.

Occlusal Table: Located on the combined root trunk.

Occlusal Surface: On the distal aspect, more sulci are visible.

Mesial Marginal Groove: On the distal aspect, no mesial marginal groove.

Distal Fossa: On the distal aspect, no distal fossa.

Root Furcation: On the distal aspect, the root furcation is rather faint.

Crown Outline: MN; Hexagonal crown outline.

Two Mesiobuccal and Distobuccal Angles: MN; The mesiobuccal and distobuccal angles are clearly defined.

Mesial and Distal Borders: MN; The mesial and distal borders converge lingually.

Middle Lobe and Buccal Ridge: MN; Buccal surface: The middle lobe and buccal ridge are the most prominent on the buccal surface.

Occlusal Table: MN; Trapezoidal occlusal table.

Buccal Cusp: MN; The buccal cusp is larger than the lingual cusp.

Buccal Cusp Ridge: MN; The buccal cusp ridge runs mesiodistally and buccolingually, giving the cusp a rotated appearance.

Cusps: MN; The buccal cusp is inclined distally and the lingual cusp is inclined mesially.

Two Triangular Ridges: MN; The two triangular ridges run from the central point of the cusp to the center of the occlusal surface, forming an angle.

Buccal Ridge: MN; The buccal ridge is clearly defined and shows three lobes on the buccal surface.

Mesial Marginal Ridge: MN; The mesial marginal ridge is slightly shorter than the distal marginal ridge.

Central Groove: Long.

Other Grooves: Mesial marginal groove and a few accessory grooves.

MN: This stands for “Mesiodistal View” or “Mesial View.” I’ve included it here to help clarify which characteristics are being described from which perspective.