Dental Anatomy: Permanent Maxillary Molars

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Questions and Answers

What is the characteristic of the mesio-buccal cusp?

It has a sharper angle at its mesial and distal slopes.

It has a right angle at its mesial and distal slopes.

It is broader than the disto-buccal cusp. (correct)

It is smaller than the disto-buccal cusp.

How many cusps are visible from the buccal aspect?

4 (correct)

What is the characteristic of the buccal developmental groove?

It starts at the cervical and terminates apically. (correct)

It starts at the occlusal and terminates at the cervical.

It starts at the center and curves distally.

It is not visible from the buccal aspect.

What is the characteristic of the disto-lingual cusp?

It is a small, spheroidal, smooth cusp. Signup and view all the answers

What is the characteristic of the lingual developmental groove?

It starts at the center and curves distally. Signup and view all the answers

How many roots do permanent maxillary molars have?

Three Signup and view all the answers

What is the characteristic of the cusp of Carabelli?

It is located 1.5 mm cervical to the mesio-lingual cusp tip. Signup and view all the answers

What is the main function of maxillary molars?

Grinding and supporting muscles of mastication Signup and view all the answers

How many roots are visible from the lingual aspect?

3 Signup and view all the answers

What is the characteristic of the distal outline of the lingual aspect?

It is semicircular. Signup and view all the answers

What is the shape of the occlusal outline of the maxillary first molar?

Rhomboidal Signup and view all the answers

What is the name of the non-functional cusp on the lingual surface of the mesio-lingual cusp of the maxillary first molar?

Cusp of Carabelli Signup and view all the answers

At what age do maxillary first molars erupt?

6 years Signup and view all the answers

When does the first evidence of calcification of maxillary first molars occur?

At birth Signup and view all the answers

How many well-separated and well-developed roots does the maxillary first molar have?

Three Signup and view all the answers

What is the direction of the convexity of the cervical line on the buccal aspect of the maxillary first molar?

Toward the root Signup and view all the answers

What is the shape of the buccal outline at the junction of the cervical third and middle third?

Crest of curvature Signup and view all the answers

What is the characteristic of the mesio-buccal and disto-lingual line angles?

Acute Signup and view all the answers

What is formed by the union of the triangular ridge of the disto-buccal cusp and the distal ridge of the mesio-lingual cusp?

An oblique ridge Signup and view all the answers

Where is the mesial marginal ridge located?

At the level of 1/5 the height of the crown Signup and view all the answers

What is the shape of the lingual root from the mesial aspect?

Banana shape Signup and view all the answers

How many major fossae are there on the occlusal surface of the tooth?

Two Signup and view all the answers

What is the location of the mesial triangular fossa?

Distal to the mesial marginal ridge Signup and view all the answers

What is the difference between the mesial and distal marginal ridges?

The distal marginal ridge is located more cervically Signup and view all the answers

What is the shape of the occlusal outline?

Rhomboidal Signup and view all the answers

How many developmental grooves are there on the occlusal surface of the tooth?

Six Signup and view all the answers

What is the location of the central pit?

At the junction between the central groove and the buccal developmental groove Signup and view all the answers

What is the order of the cusps from largest to smallest?

Mesio-lingual, mesio-buccal, distolingual, disto-buccal Signup and view all the answers

What is the length of the distal bifurcation?

5mm Signup and view all the answers

What is the direction of the distal oblique groove?

Oblique direction Signup and view all the answers

How many roots can be seen from the distal aspect?

3 roots Signup and view all the answers

What is the location of the distal pit?

At the junction between the distal fossa and distal triangular fossa Signup and view all the answers

Study Notes

Permanent Maxillary Molars

The largest and strongest teeth in the maxillary arch, with three roots: two buccal and one lingual (palatal).
They erupt behind the deciduous molars and have a main function of grinding food and supporting the muscles of mastication and vertical dimension.

Maxillary First Molar

The largest tooth in the maxillary arch.
Principal identifying features:
- Rhomboidal occlusal outline.
- The presence of a fifth cusp (the cusp of Carabelli) on the lingual surface of the mesio-lingual cusp.
- The presence of an oblique ridge extending from the mesiolingual cusp to the disto-buccal cusp.
- Three well-separated and well-developed roots: two buccal and one lingual, with the lingual root being the longest.
- Eruption time at 6 years, with first evidence of calcification at birth.

Buccal Aspect

The crown is roughly trapezoidal, with the cervical line showing very little convexity, directed towards the root.
Mesial outline of the crown is straight until it reaches the contact area, then convex to the tip of the cusp.
Distal outline of the crown is convex, with the contact area located at the center of the middle third.
Mesio-buccal cusp is broader than the disto-buccal cusp, with the mesial and distal slopes meeting at an obtuse angle, and the mesial and distal slopes of the disto-buccal cusp meeting at a right angle.

Lingual Aspect

Semicircular distal outline from the cervical to the occlusal tip of the cusp.
Mesial outline is the same as in the buccal aspect.
Lingual cusps only are visible.
Mesio-lingual cusp is the largest, accounting for 3/5 of the mesio-distal width of the crown, with an obtuse angle.
Disto-lingual cusp accounts for 2/5 of the mesio-distal dimension, with no angle visible at the tip due to its small spheroidal smooth cusp.
Lingual developmental groove starts at the center mesio-distally, curves sharply distally, and continues on the occlusal surface.

Mesial Aspect

Buccal outline has a crest of curvature at the junction of the cervical third and middle, with a convex outline to the crest of curvature, then slightly concave to the junction of the middle and occlusal third, and convex again to the tip of the cusp.
Lingual outline has a crest of curvature within the middle third, with a convex pattern until it reaches the tip of the cusp.
Mesial marginal ridge is located at a level 1/5 the height of the crown.
Cervical line curves occlusally about 1 mm.
Mesial contact area is buccal to the bucco-lingual center of the crown at the junction of the occlusal and middle third.

Distal Aspect

General outline is similar to the mesial aspect, except:
- Bucco-lingual measurement is more mesially than distally.
- Distal marginal ridge is located more cervically, so part of the occlusal surface is visible.
- Curvature of the cervical line is straight zero.
- All three roots are visible, with the distobuccal root being the smallest.
- Distal bifurcation is 5 mm in length, while mesial aspect is 3 mm in dimension.

Occlusal Aspect

Occlusal outline is rhomboidal, with a greater bucco-lingual measurement mesially than distally, and a greater mesio-distal measurement lingually than buccally.
Four well-developed cusps are visible:
- Mesio-lingual cusp is the largest.
- Mesio-buccal cusp.
- Disto-lingual cusp.
- Disto-buccal cusp.
- Cusp of Carabelli (secondary cusp).
Mesio-buccal and disto-lingual line angles are acute, and the mesio-lingual and disto-buccal line angles are obtuse.
Oblique ridge is formed by the union of the triangular ridge of the disto-buccal cusp and the distal ridge of the mesiolingual cusp, crossing the occlusal surface obliquely.
Four fossae are present:
- Mesial central fossa.
- Linear distal fossa.
- Mesial triangular fossa.
- Distal triangular fossa.
Six developmental grooves are present:
- Central developmental groove.
- Buccal developmental groove.
- Distal oblique groove.
- Lingual developmental groove.
- Transverse groove of the oblique ridge.
- Fifth cusp groove.
Three pits are present:
- Central pit.
- Mesial pit.
- Distal pit.

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Description

This quiz covers the characteristics and functions of permanent maxillary molars, including their roots, eruption, and role in mastication and vertical dimension.