Permanent Maxillary First Molars

• Permanent Maxillary molars are represented by the Upper 1st molar.

Maxillary Molars

• Permanent maxillary molars erupt 6 months to 1 year after the corresponding permanent mandibular molars.
• The first permanent teeth to erupt are in the maxillary arch.
• These molars are the largest and strongest teeth in the maxillary arch.
• Maxillary molars are usually shorter occluso-cervically compared to anterior teeth crowns.
• The crown is centered over the root with no lingual inclination.
• Each maxillary molar usually has four major cusps.
• There are 2 cusps on the buccal part, and two on the palatal part, of the occlusal table of each maxillary molar.
• An Oblique Ridge is a unique feature on the occlusal table of maxillary molars.
• The oblique ridge crosses the occlusal table obliquely.
• Mandibular molars never have an oblique ridge.
• Maxillary molars are wider bucco-lingually than mesio-distally.
• Mandibular molars are wider mesio-distally.

Permanent Maxillary First Molar

• The crown has four well-formed cusps: MB (mesiobuccal), DB (distobuccal), MP (mesiopalatal), and DP (distopalatal).
• A tubercle of Carabelli exists on the MP cusp.
• An oblique ridge is on the occlusal surface between MP and DB cusps.

Buccal Aspect

• The buccal aspect of the tooth appears trapezoidal.
• The M. outline is straight from the cervical line to the contact area.
• The D. outline is convex from the cervical line to the contact area, then more convex to the B cusp tip.
• The M. Contact area is at the junction of the occlusal and middle third.
• The D. Contact area is at the center of the middle third.
• The DB cusp is sharper than the MB cusp.
• The MB Cusp is broader than the DB cusp.
• The tip of the MP cusp is seen between the two B cusps.
• Maximum convexity is at the C1/3 cervical ridge.
• The cervical line is slightly convex rootwise.
• The buccal development groove extends from the occlusal surface to the middle third.
• The development groove may fade out, end in a buccal pit, or branch into two small grooves.
• Above the cervical line, the root trunk divides at a bifurcation area into MB and DB roots.
• The bifurcation is around 4 mm from the cervical line.
• The palatal root, or P, is seen between the two roots.
• The MB root curves distally at the apical third.
• The DB root curves mesially at the apical third.
• The palatal root is straight and conical.
• The Palatal root is the longest and lies between the MB and DB roots.

Palatal Aspect

• The palatal aspect appears trapezoidal, with a short side cervical.
• Only palatal cusps can be seen from this aspect.
• The MP cusp is larger than the DP cusp.
• Tubercle of Carabelli is attached to the MP cusp and measures 2mm cervically.
• There is no lingual convergence.
• The mesial outline is straight.
• The distal outline is convex.
• Maximum convexity is at the middle third.
• A palatal developmental groove separates the two palatal cusps.
• The groove separates the two palatal cusps and ends at the center of the palatal surface, possibly fading out or terminating in a palatal pit.
• From that point, a shallow depression extends cervically and continues on the root to its middle third.
• All three roots are visible from this aspect.
• The root trunk is continuous with the crown cervically.
• the palatal root is conical with a blunt, round apex.
• Portions of MB and DB roots are visible in the background.
• The apex of the palatal root is on line with the palatal groove.

Proximal Aspects

• The mesial aspect is visible from the front and the distal aspect from the back.

Mesial Aspect

• The shape is a trapezoid.
• The Buccal outline is convex in the cervical 1/3, concave at the middle 1/3, then convex at the occlusal 1/3.
• The palatal outline is convex with the crest of curvature at the middle third, then it dips inwards to illustrate the "tubercle of Carabelli."
• The Mesial marginal ridge is irregular, curved cervically, at occ ¼.
• M. Contact area is at the junction of the middle and occlusal 1/3 buccally.
• The Cervical line is curved occlusally about 1 mm.
• The MB root is broad and flattened.
• The MB root covers 2/3 width of the crown cervically and has a curved buccal outline and a straight palatal outline; it ends at a blunt apex.
• The palatal root is longer but narrower, diverging in the middle and apical 1/3; it has a convex palatal outline and a concave buccal outline (banana shape).
• Only 2 roots are seen.
• The MP is broad & flattened, covering 2/3 width of the crown cervically.
• The P is longer and narrower than the MB, diverging in the middle and apical 1/3 with a convex palatal outline, and a concave buccal outline.

Distal Aspect

• The outline is similar to the mesial aspect.
• The crown is narrower B-L due to distal convergence.
• The DMR is slightly cervical, exposing part of the occlusal surface.
• The contact area is more cervical than the mesial contact area.
• Root furcation is more apical, at 5 mm or longer.
• Visible roots include P, DB, and part of MB.
• Key distinctions between distal and mesial aspects:Distal Convergence vs Wider mesial surface, Convex distal surface vs Flat mesial surface, and Distal marginal ridge curved cervically vs Mesial marginal ridge less curved.
• The straight cervical line is on the distal side vs the cervical line being concave root wise on the mesial.
• The Root trunk measures 5mm on the distal vs 3mm on the mesial.
• The distal aspect has 3 roots that can be seen vs the mesial where only 2 are visible.

Occlusal Aspect General Features

• The geometric shape is rhomboidal.
• The tooth is wider mesially than distally and wider palatally than buccally with disto-buccal convergence.
• The Mesial marginal ridge is longer and well developed compared to the distal marginal ridge.
• The mesio-palatal cusp is the largest cusp, and it has a large triangular ridge joining the disto-buccal triangular ridge to form the oblique ridge; also, the mesio-buccal triangular ridge helps form a transverse ridge.
• MP & DB angles are obtuse (more than 90°).
• MB & DP angles are acute (less than 90°).
• There is a supplemental elevation: the tubercle of Carabelli, attached to the MP cusp.
• Cusp size relationship is MP>MB>DB>DP>tubercle of Carabelli

Pulp Cavity

• The pulp chamber is broader bucco-palatally than mesio-distally.
• There is a pulp horn beneath each cusp.
• The floor of the pulp chamber is apical to the cervical line.
• The tooth contains 3 root canals, sometimes with two canals in the mesio buccal root.