Posterior Teeth - Premolars

Front 1

On the BUCCAL view of Maxillary 1st premolar, where is the cusp tip located mesiodistally?

Back 1

Cusp tip is so offset the the distal.
-Mesiocclusal is LONGER and STRAIGHTER
-The distocclusal is SHORTER and CURVED

Front 2

What shape is the maxillary 1st premolar from the MESIAL view.

Back 2

•
Trapezoidal in shape

Front 3

Maxillary 1st Mesial View - 3 features
-cusp height
-concavity
-contact pt

Back 3

Easy to observe the difference in height between the lingual and buccal cusps
•
Mesial concavity
•
The contact is roughly circular and offset to the buccal

Front 4

Maxillary 2nd premolar, MESIAL view
-cusp height
-concavity
-mesial groove?

Back 4

•
Notice the nearly equal buccal and lingual cusp length
•
No mesial concavity
•
No mesial groove

Front 5

Maxillary 1st and 2nd premolar differences:(5)

Back 5

Cusp height difference (1 has the greater diff.)
•
Crown concavity (1 has this)
•
Marginal ridge groove (1 has this )
•
Number of roots (1 has 2)
•
Developmental root depression (1 has depressions)

Front 6

MANDIBULAR premolar arch traits
-resemblance to each other
-resemblances to other teeth in the crown

Back 6

The two mandibular premolars do not resemble each other the way the two maxillary premolars do
•
The first premolar reflects the transition from canine, and the second premolar shows the change into a molar
•
Marginal ridges demonstrate the similarity between canine and 1stpremolar while the 2ndpremolar displays a horizontal marginal ridge like other posterior teeth

Front 7

Mandibular First Premolar
Development

Back 7

calcification……..1 ¾ ‐2yrs enamel……… 5‐6yrs
Eruption……… 10‐12yrs
root………….. 12‐13yrs

Front 8

Mandibular Second Premolar
Developmental Table

Back 8

Calc….... .2 ¼ to 2 ½yrs
f Enamel……....6 to 7yrs
eruption……….11 to 12 yrs
Root…………..13 to 14 yr

Front 9

UNIQUE CHARACTERISTICSMandibular First Premolar(Type Traits)
-grooves?
-FL crown dimension?
-FL vs MD dimensions?

Back 9

Presence of mesiolingual groove
•
F‐L crown dimension –smallest of any posterior tooth
F‐L –MD crown dimensions –least difference in mandible

Front 10

UNIQUE CHARACTERISTICSMandibular First Premolar(Type Traits)
-Distal vs Mesial Contact?
-lingual view of occlusal surface?
-Facial vs. lingual cusp heights?

Back 10

•
Distal contact occlusal to Mesial contact (the reverse of all other teeth, along with max. primary canine)
•
Occlusal surface visibility can be viewed lingually
•
Facial cusp is much higher than lingual

Front 11

UNIQUE CHARACTERISTICSMandibular First Premolar(Type Traits)
-mesial vs distal location of marginal ridges
-occlusal surface Lean?
-Mesial Marginal ridges slope?

Back 11

Marginal ridge locations –M more cervical than D marginal ridge
•
Occlusal surface tilts lingually
•
Mesial marginal ridge slopes lingually at about a 45°angle

Front 12

UNIQUE CHARACTERISTICS Mandibular Second Premolar
-Lingual cusp (#)?
-Groove(s)?
-Fossa?

Back 12

Only premolar with multiple lingual cusps
•
Only premolar with a lingual groove
•
Only premolar with a central fossa

Front 13

UNIQUE CHARACTERISTICS Mandibular Second Premolar
-Lingual 1/2 vs the facial 1/2 ?
-Location of Lingual HOC?

Back 13

MD dimension of lingual half of crown greater than facial ½ ‐shared with maxillary 1stmolar
•
Lingual height of contour in the occlusal (or middle)1/3rdof the crown

Front 14

Mandibular Second Premolar
Lingual View
Two cusp type
-Which cusps are present?
-grooves present?
-Single cusp height, relatively?

Back 14

Just one buccal and one lingual cusp present
1) No lingual groove
2) The single cusp is approximately the same height as the ML cusp of the 3 cusp type

Front 15

Mandibular Second Premolar
OCCLUSAL VIEW
-outline shape
-relative lingual convergence?
-Shape of 3 cusp form (a letter)?

Back 15

Square outline
•
Not nearly as severe a convergence toward the lingual as the mandibular first premolar
•
Y type‐the three cusp type takes on the form of a “Y”

Front 16

Mandibular Second Premolar
Occlusal View
-2 cusp type resembles which letter(s)?
-Which type is the most common form of 2nd MAND. pmolar, in MOST cases?

Back 16

•
U or H type‐Two cusp type resembles a “U” or “H”
•
The Y type is the most common form of a second mandibular premolar and is present in the majority of cases

Front 17

Distinguishing Characteristics Mandibular Premolars

Back 17

•
Occlusal crown outline form
•
Presence of a ML groove
•
Number of cusps and pits / fossae
•
Mesial marginal ridge form and location
•
Presence of a lingual groove

Front 18

Distinguishing Characteristics Mandibular Premolars

Back 18

•
F ‐L cusp height difference
•
MD crown dimension lingually
•
FL position of facial cusp
•
Occlusal surface visibility
•
Occlusal groove form
•
Proximal contact locations

Front 19

Maxillary First Molar
Development

Back 19

I calcification……Birth
enamel…….. 21/2‐3 yrs
Eruption………….6‐7 yrs
root………… .9‐10 yrs

Front 20

Maxillary Second Molar
Development

Back 20

calcification…… 2 ½‐3 yrs enamel……. .7‐8 yrs
Eruption……… .12‐15 yrs
root…………. 14‐16 yrs

Front 21

Maxillary Third Molar
Development

Back 21

calcification…… 7‐9 yrs
enamel ……..12‐16 yrs
Eruption…………..17‐21 yrs
root…………. 18‐25 yrs

Front 22

Molar Functions
-Chewing?
-facial dimensions and support?
-Arch continuity?

Back 22

MASTICATION OF FOOD.
•
Maintain the vertical dimension of the face‐keeping the chin a proper distance from the nose
•
Have a minor role in esthetics or keeping the cheeks normally full or supported, as well as keeping the chin a proper distance from the nose.
•
Important in maintaining continuity within the dental arches, thus keeping other teeth in proper alignment (more on this later).

Front 23

Where is the buccal HOC on post teeth?
-Lingual?

Back 23

Buccal HOC is in the gingival 3rd
Lingual HOC in the middle 3rd

Front 24

What is the position of the marginal ridges relative to the long axis on post. teeth?

Back 24

Perpendicular (horizontal)

Front 25

Where do all Mandibular post. teeth crowns lean?

Back 25

All lean lingually AND distally.

Front 26

In what direction – from the occlusal view – do all teeth taper?
There are 2 exceptions, what are they?

Back 26

All teeth taper towards the lingual.
The exceptions are the Mandibular 1st and 3 cusp Mandibular 2nd premolars

Front 27

What shape are ALL premolars from the facial view?

Back 27

All are pentagonal – same as K9s.

Front 28

What is the larger dimension on premolars- faciolingual or mesiodistal?

Back 28

All premolars are wider faciolingually then mesiodistally

Front 29

Which premolars (which arch) are more similar?

Back 29

Maxillary are more similar than mandibular

Front 30

In the Maxillary arch which premolar is larger 1st or 2nd?
The mandibular?

Back 30

In the maxillary arch the first premolar is larger than the 2nd.
The Mandibular 2nd is larger than the 1st (considerably larger)

Front 31

In the Maxillary arch which dimension – buccolingual or mesiodistal – is larger?
The mandibular?

Back 31

In the maxillary arch the buccolingual dimension is wider than the mesiodistal
In the mandibular, these dimensions are approximately equal.

Front 32

What are the relative cusp sizes of maxillary premolars? How many are typical?

Back 32

Maxillary premolars have 2 cusps that are relatively equal in size.

Front 33

In the mandibular arch what are the relative cusp sizes? How many are possible?

Back 33

These may have more than 2 cusps and the Buccal cusp is larger.

Front 34

Of the arches, which premolars are centered over their roots and which possess a lingual lean?

Back 34

The maxillary molars are centered over their roots while the Mandibular lean lingually.

Front 35

Which premolar has 2 root branches?

Back 35

The Maxillary 1st, is the only premolar to have 2 root branches.

Front 36

What are the functions of the premolars?

Back 36

Supplement the grinding of the molars
Aid in shearing of food like the K9s
Aid in sustaining the vertical dimension of the mouth and supporting the corners – keeps them from sagging.
Less esthetic and phonetic function than the K9s but more than the molars.

Front 37

Maxillary Premolar Development

Back 37

Init. Of calc. - 1.75 – 2 yrs
Enamel 5-6 yrs
Eruption 10-11
Root 12-13

Front 38

Maxillary 2nd Premolar Development

Back 38

Init. 2-2.25
Enamel 6-7
Eruption 10-12
Root 12- 14

Front 39

Maxillary 1st unique characteristics - which cusp ridge is longer?
- On which ridge does it have a groove?
Root -?
Crown ?
Central Development Groove?

Back 39

Mesial Cusp ridge is longer
Has a Mesial groove
Root depression present
Crown Concavity and Central Development Groove depth.

Front 40

Maxillary 2nd premolar unique characteristics?
-Symmetry relative to other post.
-Cusp heights relative to each other
-distance of fossae

Back 40

Maxillary 2nd is more bilaterally symmetric than any other posterior tooth
Cusp heights are closer than other premolars
The mesial and distal fossa are closer than other post. teeth

Front 41

What is significant about the Maxillary 1st premolar occlusal cervical distance?

Back 41

Greatest OC distance of all posterior teeth. Shorter than all anteriors.

Front 42

Which anterior tooth does the maxillary 1st premolar resemble from the buccal view?

Back 42

The K9

Front 43

How many developmental depressions does the maxillary 1st premolar have from the Buccal?
How many Lobes of formation?
Perikymata Present?

Back 43

It has 2 dev. Depressions – mesio and distobuccal
These divide it into 3 vertical 3rds – lobes of formation.
It does have perikymata