Chapter 17: Permanent Posterior Teeth

Occlusal

The masticatory surface of posterior teeth is its _______ surface.

HINT: different from anteriors

Cusp ridges

Some anatomists liken a cusp to a gothic pyramid with four ____ ____ descending from each cusp tip.

Triangular ridges

Cusp rides that descend from the cusp tips toward the central part of the occlusal table.

Occlusal Table

The occlusal surface of permanent posteriors creates an inner _______ ______ bordered by marginal ridges.

Transverse ridge

A collective term given to the joining of two triangular ridges crossing the occlusal table transversely, moving from Labial to Lingual outline.

Marginal Grooves

Developmental grooves that cross marginal ridges and serve as spillways, allowing food o escape during mastication.

Increases

Supplemental Grooves are also prominent in posterior and the amount of these grooves _______ as you travel more posteriorly in the arches.

Complex pit and groove patterns

What characteristic put posterior teeth as an increased risk of caries due to increased biofilm retention.

Succadaneous;Nonsuccadaneous

Premolars are _______ while molar are _________.

HINT: which teeth do they replace?

Grinding

Premolars function to assist the molars in _________ during mastication because of the broad occlusal surface and prominent cusps, especially buccal cusps. They also help maintain the height of the lower third of the vertical dimensions of the face.

Shorter

As posterior teeth, premolars have a _______ crown than anterior teeth.

Buccal ridge

The buccal surface of premolars is more rounded and has a prominent centrally located _______ _____.

True

TRUE/FALSE: first premolars are usually extracted more often than second premolars.

Larger

Maxillary first premolars are _______ than maxillary second premolars.

Smaller

Mandibular first premolars are _______ than mandibular second premolars.

Maxillary first premolars

All premolars have one root EXCEPT for…?

Lingual

Maxillary premolars have two cusps almost of equal size; Mandibular premolars can have more than two cusps, but ______ cusps are always smaller.

Maxillary sinus

The roots of maxillary premolars ay penetrate the anterior part of the ______ _____ as a result of accidental trauma or during tooth extraction because of the close relation of these roots to this anatomical structure. Discomfort in this area can be mistakenly interpreted as tooth-related from the maxillary premolar.

MAXILLARY FIRST PREMOLARS

TOOTH NUMBERS: #5 and #12

ERUPTION: 11 years

CROWN FEATURES: angular had with sharply defined outline. Higher buccal cusp than lingual.

ROOTS: bifurcated. Rounded roots that taper to sharp apices. The buccal root is larger but not longer.

BUCCAL: crown is widest mesiodistally of all premolars. Mesial outline more rounded. Buccal cusp is high and sharp and located slightly distal. Mesial cusp slope longer than distal cusp slope.*

LINGUAL: lingual cus offset toward mesial.

PROXIMAL: mesial marginal ridge, mesial root concavity and developmental depression, more occlusal mesial CEJ curvature.

OCCLUSAL: crown outline hexagonal, prominent buccal ridge of buccal cusp, 4 triangular grooves, 1 transverse ridge.

MAXILLARY SECOND PREMOLARS

TOOTH NUMBERS: #4 and #13

ERUPTION: 11 years

CROWN FEATURES: less angular, more rounded and more crown variations.

ROOTS: single root and longer than first.

BUCCAL: cusps are more equal in height. Fairly symmetrical.

LINGUAL: larger lingual cusp, almost same height at buccal.

PROXIMAL: NO mesial surface features like first.

OCCLUSAL: more rounded and larger than first. Shorter central groove that ends in mesial and distal pits. Supplemental grooves.

False

TRUE/FALSE: mandibular premolars resemble each other closely like maxillary premolars do.

True

TRUE/FALSE: mandibular premolars can have more than two cusps, however the lingual cusp is always smaller.

MANDIBULAR FIRST PREMOLARS

TOOTH NUMBERS: #21 and #28

ERUPTION: 11 years

CROWN FEATURES: more resembles mandibular canine. Long and sharp buccal cusp that is the only functional cusp.

ROOTS: single root, smaller and shorter than second. Deep groove on distal surface.

BUCCAL: almost symmetrical outline. Shorter mesial cusp slope than distal. Distal outline is rounder and shorter.

LINGUAL: lingual cusp is small and nonfunctioning.

PROXIMAL: mesial marginal ridge, mesiolingual groove, and more occlusal mesial CEJ curvature.

OCCLUSAL: crown outline diamond shape. 4 triangular grooves. 1 transverse ridge. SNAKE EYES!

MANDIBULAR SECOND PREMOLARS

TOOTH NUMBERS: #20 and #29

ERUPTION: 11 years

CROWN FEATURES: two cusp type forms U shape groove pattern, three cusp type forms Y shape groove pattern(1 buccal, 2 lingual)

ROOTS: single root, larger and longer than first. Proximal root concavities. Blunt apex.

BUCCAL: shorter buccal cusp than first and more rounded.

LINGUAL: lingual cusps are smaller than buccal cusp. May have one or two. In three cusp type- mesiolingual cusp is larger.

PROXIMAL: crown is wider than first buccolingually and lingual cusps are larger. More of occlusal surface can be seen from distal as marginal ridge is more cervically located.

OCCLUSAL: crown outline is square. 4 triangular grooves.

Three cusp

Which is more common, a two cusp or three cusp mandibular second premolar?

Partial

Permanent mandibular second premolars are commonly involved in _______ anodotia and thus may be congenitally missing.

True

TRUE/FALSE: Grooves and Pits are not only on the occlusal surface of both maxillary and mandibular molars, but also on the lingual surfaces of maxillary molars and buccal surfaces of mandibular molar.

Mulberry Molars

Enamel Hypoplasia that is caused by treponema pallidum and results in a crown with an abnormal shaped occlusal surface characterized by very-like nodules or tubercles of enamel instead of cusps.

Mulberry molars, enamel pearls, Dilaceration of roots

What are three common developmental disturbances in molars?

Wider;Opposite

All maxillary molars are _______ buccolingually than mediodistally.

Are Manidbular molars the same or opposite?

Oblique ridge

A unique feature in occlusal table of maxillary molars, a type of transverse ridge that crosses the occlusal table obliquely from distobuccal cusp to mesiolingual cusp.

MAXILLARY FIRST MOLAR

TOOTH NUMBER: #3 and #14

ERUPTION: 6 years

CROWN: largest crown in permanent dentition. Five developmental lobes (two bucca, three lingual).

ROOTS: three roots, larger and more divergent than second. THICK root trunk.

BUCCAL: mesiobuccal cusp outline is wider, buccal groove divides occlusal outline symmetrically.

LINGUAL: lingual surface is more rounded. Mesiolingual cusp is largest and not as sharp as distolingual cusp. Possible fifth cusp of carabelli on mesiolingual cusp.

PROXIMAL: more prominent mesial marginal ridge.

OCCLUSAL: 4 or 5 cusps. 1 oblique ridge and 1 transverse ridge. 3 triangular grooves. 4 fossa.

Maxillary molars

Most common teeth involved in concrescence?

MAXILLARY SECOND MOLARS

TOOTH NUMBERS: #2 and #15

ERUPTION: 12 years

CROWN: lots of variation, especially in distolingual cusp size. May have 3 or 4 cusps.

ROOTS: 3 roots. Shorter, less divergent and more parallel than first. Narrower furcation notches.

BUCCAL: buccal groove located more distally. Mesiobuccal cusp is longer and less sharp cusp tip than distobuccal cusp.

LINGUAL: larger and longer mesiolingual cusp. Lingual pit usually present at the end of distolingual groove.

PROXIMAL: smaller distobuccal and distolingual cusp than first.

OCCLUSAL: crown outline is rhomboidal and heart-shaped. Less prominent oblique ridge, but other occlusal features similar to first.

MAXILLARY THIRD MOLARS

• #1 and # 16, erupt around 17 years

• Three cusps with heart shaped crown outline (two buccal one lingual) or Four cusps with rhomboidal shaped crown outline

• Trifurcated bust sometimes roots fuse and look like one. Distobuccal root usually smallest and found tucked under crown.

• Clinical Consideration include failure to erupt, Dentigerous cyst formation, location gives increased risk of disease, commonly exhibit partial anodontia, accessory roots

Maxillary third molars and mandibular central incisors

What two teeth in the entire dentition only have one antagonist?

Microdontia

Maxillary Third Molars commonly exhibit partial _______ which leads to a smaller molar crown with one cusp or a peg molar.

Lingual

Quite distinct from maxillary molars, the buccal crown outline of all mandibular molars show strong _____ inclination when viewed from proximal, like the nearby premolars.

Instrumentation

Narrow lingual surfaces and lingual inclination of Manidbular molars present difficulties in __________.

MANDIBULAR FIRST MOLAR

TOOTH NUMBER: #19 and #30

ERUPTION: 6 years

CROWN: first permanent tooth to erupt in oral cavity. 5 cusps (3 buccal, 2 lingual).

ROOTS: bifurcated. Shorter root trunk than second. If one root is longer, it’s usually the mesial one. Fluting present on root surfaces, especially mesial.

BUCCAL: widest tooth mesiodistally because of fifth distal cusp. Mesiobuccal cusp is largest on buccal side. Buccal ridge. Mesiobuccal groove.

LINGUAL: smaller than buccal surface.

PROXIMAL: mesial marginal groove

OCCLUSAL: crown outline pentagonal. Distal cusp is smallest. Y-shaped groove pattern.

Buccal

Pits may occur on the ______ surface of mandibular first molars and are at an increased risk of caries because both increased biofilm retention and thinnest of enamel forming walls of pit.

MANDIBULAR SECOND MOLARS

TOOTH NUMBERS: #18 and #31

ERUPTION: 12 years

CROWN: smaller than first. Four cusps of equal size.

ROOTS: bifurcated, two roots. Smaller, shorter, and less divergent than first. Longer root trunk. Shallower root depressions.

BUCCAL: buccal groove divides same sized cusps.

LINGUAL: same size mesiolingual and distolingual cusps.

PROXIMAL: crown tapers distally.

OCCLUSAL: crown outline is rectangle. cross-shaped groove pattern. 2 transverse ridges.

MANDIBULAR THIRD MOLARS

• #17 an #32, erupt around 17

• Rounded mesial contact when fully erupted is more cervical than any other molar

• Variable shape, usually smaller in all dimensions than second

• Crown tapers distally

• Wrinkled irregular groove pattern

• Two short roots fused

• Clinical considerations include failure to erupt, partial eruption (operculum), involved in partial anodontia, and formation of Dentigerous cyst

Pericoronitis

Due to its posterior arch position, this infection in mandibular third molars can become serious itch resultant Ludwig angina, cellulitis of submandibular space, and thus impact breathing.