Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Craniofacial & tooth biology > Theme I: Tooth morphology, occlusion & chronology > Flashcards

Theme I: Tooth morphology, occlusion & chronology Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

How to distinguish upper 1 and 2

A

1 = broader, square crown.

2= smaller and narrower
-mesial angle more acute. Distal angle more obtuse and rounded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How to distinguish upper and lower incisors

A

Lower= smaller and narrower relative to height

  • Roots more compressed mesio-distally
  • Less rounded distal angle
  • Poorer development of the marginal ridges
  • Lower cingulum so shallow fossa
  • Incisal edge displaced lingually (1) or distally (2)
  • Deep grooves on distal root surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How to distinguish the upper and lower canines

A 
-Lower:
= shorter roots
-smaller and narrower relative to height
-Inclination of the mesial and distal slopes is less pronounced, so less pointy
-More rounded cingulum
-Lower marginal ridges with shallower lingual fossa
-Tip of cusp displaced lingually
-Root more compressed mesio-distally
-Root may be bifurcated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which teeth can be extracted by rocking and rotating

A 
Rocking = Lower 1,2,3. Upper 4,5
Rotating = Upper 1,2,3. Lower 4,5. Upper 8 if roots fused
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which is the hardest tooth to extract

A

Upper 6 due to long strong roots

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How to distinguish the lower permanent 1 and 2

A

2 = bigger crown

  • Longer and wider
  • Distal angle more acute
  • Incisal edge curved distally and lingually (whereas 1 is just lingually)
  • longer root
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Out of all the canines, which one has a longer mesial slope compared to its distal slope

A

Primary upper canine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which permanent premolar has 2 roots

A

upper first premolar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Difference between upper 4 and 5

A

-4 has 2 roots, 5 has 1 root

  • 4 = buccal cups higher than palatal
  • 5= cusps equal height and lower
4= occlusal angle more angular. Has canine groove and fossa on mesial crown
5= smaller, rounder more symmetrical crown. Wider marginal ridges.
4= shorter distal slope
5= shorter mesial slope
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Difference between lower 4 and 5

A

4= canine groove.

  • Less symmetrical
  • Less defined central fissure
  • Steaper buccal cusp, smaller lingual
  • No mesial and distal pits
  • smaller distal slope

5= Larger and more circular crown

  • Buccal cusp not as centred over root trunk
  • Well defined central fissure
  • Has mesial and distal pits
  • smaller mesial slope
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Difference between lower and upper premolars

A
  • Lower= have rounder conical crowns and roots that can be rotated between fingers.
  • Buccal cusp inclines lingually more
  • More prominent buccal cusps than lingual
  • Can have 3rd DL accessory cusp

Upper= flattened mesio-distally.

  • Wider buccal-lingually
  • Larger lingual cusps
  • Strong central grooves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the smallest permanent premolar

A

Lower first premolar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why do lower premolars have curved buccal cusps

A

-Curve lingually to occlude with the upper teeth because the buccal cusp is the functioning cusp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Difference between upper and lower molars (excl. 3rd) shape. roots. largest cusp.

A
  • Upper = 3 roots (2 buccal , 1 palatal)
  • Lower = 2 roots
  • Upper = rhomboid shape
  • Lower = Rectangular. More symmetrical cusps

Upper- mesio-palatal cusp biggest
Lower- mesio-buccal cusp biggest

Lower= buccal cusps displaced lingually as they are the functioning cusps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Key features of upper 6, 7, 8 molars

A

6= tubercle of carabelli on large Mesio-palatal cusp. Common for MB canal to divide. 4 cusps

7= no tubercle. Less divergent roots than 6 so may be partly fused. 3 types:

  • Type 1= 4 cusps. Common. Similar to 6 with smaller disto-palatal cusp
  • Type 2= heart shaped. 3 cusps. No DP.
  • Type 3= Oval crown with 3 cusps in straight line. (fused MP & DB)

8= variable. Usually heart shaped. with 3 cusps. Fused roots. Smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Key features of the lower 6, 7, 8 molars

A

6= 5 cusps- extra distal cusp which is displaced buccally. Buccal cusp tips rounder and lower than lingual, and displaced lingually to occlude with uppers. Mesial root deeply grooved.

7= 4 cusps. no distal cusp. H shaped fissure. Buccal cusps lower and rounder than lingual. Less divergent roots. Wider mesio-distally than 6.

8= 4 cusps or maybe 5. Irregular branching of occlusal fissure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Explain the terms cross bite and scissor bite and the consequence.

A

-Usually upper arch is slightly wider than lower, so palatal cusps of upper are functional cusps where they contact with central fossa of lower.
-Crossbite= If the lower arch is wider, so upper teeth sit inside the lower. The buccal cusps of upper change to the functioning cusps.
=Scissorbite = If upper arch is significantly wider, so the teeth do not occlude or have contact.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Explain the terms dynamic and static occlusion. Intercuspal/ rest position. Working/ non-working side.

A

1-Static= the contact between the teeth when the mandible is not moving (side to side). Either:

  • Intercuspal- when teeth are biting together (maximum crushing of food)
  • Rest position - teeth slightly separated (majority of time like this)

2-Dynamic = contacts when mandible is moving/ chewing/ opening with lateral and protrusive excursions.

  • Working side- side that mandible is moving towards. Rotating condyle
  • Non-working side= side the mandible moves away from. Teeth separated. Orbiting condyle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Explain functioning cusp. What does the non-functioning cusp do

A
  • The cusp that bites into the central fossa of the opposing tooth, when in intercuspal position
  • Upper teeth = palatal cusp
  • Lower teeth = buccal cusp
  • Non-functioning cusp is the guiding cusp
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Explain the 3 different skeletal/ jaw relationships

A
  • 3 classes depending on the position of the the mandible in relation to maxilla
    1. Class 1= normal. Mandible is centrally related to maxilla.
    2. Class 2= Mandible is posterior/ retruded (overbite)
    3. Class 3= Mandible is anterior/ protruded (underbite)
21
Q

Explain the 3 different incisor relationships. Mention the % overbite

A
  • 3 classes depending on how the mandibular incisors occlude with the cingulum plateau of the upper incisors
    1. Class 1= Mandibular incisors occlude with or lie below the cingulum plateau [30% overbite]
  1. Class 2= incisors lie posterior to cingulum. 2 divisions depending on how patient compensates. [75-100% overbite]
    - Type 1= increased overjet. Upper are proclined or normal inclination
    - Type 2= upper are retroclined (more vertical) to compensate and occlude.
  2. Class 3= Lower incisors are anterior to the cingulum plateau. [0-20% overbite]
22
Q

Explain the 3 different molar relationships

A
  • Positions of the 1st molars in relation to each other in intercuspal position. Relate to the positions of the mesiobuccal cusp of the upper to the buccal groove of the lower. [Not always determined by jaw relationship]
  • Class I= mesiobuccal cusp of upper occludes with buccal groove of lower
  • Class II= upper molar is a full tooth width mesial compared to in class I. Moved anteriorly so cusp is beyond the groove.
  • Class III = upper molar is a full tooth width distal to class I. Moved posteriorly
23
Q

Where should the upper 1st molars and the canines be situated with respect to the lower teeth

A
  • Upper 1st molar = slightly behind the lower 6. Upper Mesiobuccal cusp occludes with the buccal groove of the lower.
  • Upper canine= between the lower canine and first premolar.
24
Q

Differences between permanent and primary teeth. Features that affect caries risk

A

Primary are:

  • Smaller and more bulbous in shape
  • Thinner and shorter roots
  • Thinner and softer enamel so caries develops quicker.
  • Pulp larger, thinner dentine
  • Pulp horns closer to enamel so higher risk of exposure
  • Width of crowns of anterior teeth are greater relative to height
  • More proteins and less mineralised so whiter, whereas permanent are ivory coloured due to being more transparent showing the yellow dentine.
  • Less crowded so less interproximal caries
  • Molar roots more divergent to make room for permanent teeth below
  • Have a rounded labial cingulum.
  • Lower palatal cingulum with shallower fossa
25
Q

Theories on how teeth are forced out and erupt

A

-Forces from alveolar bone growth, root growth, blood pressure, tension within the PDL, tissue fluid pressure or cell proliferation.

26
Q

Describe what pre-eruptive, eruptive and post-eruptive movements are of the permanent teeth

A
  1. Pre-eruptive: movements of tooth germs within jaw before eruption. Anterior permanent teeth move into position lingually behind the primary. Posterior move into position between the roots of the primary molars.
  2. Eruptive: Tooth moves from its developmental position in alveolar crypt to its functioning position. PDL remodelled. Resorption. Exfoliation. Erupts while crown and root still forming.
  3. Post-eruption: maintenance of the erupted teeth in occlusion while the jaw continues to grow and to compensate tooth wear (bone and PDL remodelling, cellular cementum thickening)
27
Q

Root reabsorption pattern of anterior and posterior primary teeth during permanent teeth eruption. Is the pulp still in tact of the primary teeth

A
  • Anterior are positioned lingually to the primary. Intact pulp chamber.
  • Posterior positioned underneath, between the roots so root resorption occurs in an occlusal direction. Therefore resorption of pulp chamber, coronal dentine and sometimes enamel.
28
Q

Stages of tooth eruption

A
  • Permanent teeth move into position in alveolar crypt, either lingually or beneath the primary teeth.
  • Reabsorption of primary tooth root begins.
  • Primary tooth is exfoliated
  • Emergence of permanent: through alveolar bone and gingiva.
  • Clinical emergence: becomes visible in the oral cavity.
  • Root completion and closed apex.
  • Teeth in occlusion
29
Q

Why might eruption of permanent teeth be delayed

A
  • Either congenital (disease present at birth)
  • Deficiencies
  • Eruption cysts
  • Impacted teeth- Abnormal eruption pathway and lack of space. Positioned against another tooth
30
Q

What impact might the early loss of primary teeth (due to caries or extraction) have

A
  • Affects space distribution and symmetry. Adjacent teeth may tip into the space beside and cause crowding and affect other teeth erupting
  • Accelerating eruption of permanent teeth below. They might not be developed enough and have unstable roots. And there may not be enough space in the jaw so could cause overcrowding and overlapping. May not erupt in correct place.
31
Q

Most common missing teeth and why could this be

A

-3rd molars (20-30%)
-Lower 2nd premolar
- Upper lateral incisor
(then also Upper premolars and lower central incisors)

Due to these teeth being the last to erupt in their developmental sequence in their tooth class. Or due to evolution and we don’t need as many teeth anymore due to softer diet

32
Q

The different terms for describing patients with abnormal number of teeth. Causes.

A
  • Supernumerary teeth/ hyperdontia: extra teeth, can disrupt eruption of other teeth
  • Hypodontia: missing <6 teeth (excl. 3rd molars)
  • Oligodontia: absence of >6 teeth

Genetic factors can cause congenital missing teeth, or is due to trauma or infection. Mutations in Pax9 and Msx1 genes. Or evolution

33
Q

What tooth features is hypodontia associated with

A
  • Missing <6 teeth (excl. 3rd molars) Usually only affects permanent teeth.
  • Can be syndromic (associated with genetic disease) or non-syndromic (inherited)
  • Usually smaller crowns and roots
  • Enamel hypoplasia (thin enamel)
  • conical crown shape
  • Pulp chamber enlarged vertically
  • Delayed eruption
  • Retention of primary teeth (as no teeth to resorb their roots)
  • Impaction of maxillary canines (grow at odd angle)
34
Q

Explain what happens in the 3 teeth growth periods

A
  1. 0-6 years: Deciduous dentition complete from 6 months to 2.5 years.
  2. 6-12 years: Mixed dentition. Baby teeth shed and replaced by permanent
  3. 12- 18 years: Only permanent teeth. Expansion of jaw to provide space for 3rd molar to erupt.
35
Q

Why knowledge of tooth morphology and chronology is important

A
  • Morphology: to recognise abnormal conditions. Spot genetic diseases or early signs of diseases. To identify is patients are high risk for developing dental disease.
  • Chronology: comparing dental age and actual age to check if development is normal
36
Q

What needs to be taken into consideration before doing endodontic treatment for a young patient.

A

Xray is needed to check the root is complete so that the apex is closed, otherwise filling material would run out.
Delay treatment until root is complete. Put protective cap on in the mean time.

37
Q

Why might a primary tooth be retained

A

1- Hypodontia- missing permanent teeth so no root resorption so does not exfoliate
2-Or failure of successional tooth to resorb it due to an unusual course due to overcrowding. Missed the gubernacular canal that guides its eruption pathway.

38
Q

What are signs of ectodermal dysplasia

A
  • Sparse hair, unusual fingernails, distinctive facial appearance.
  • Hypodontia or oligodontia
  • Perhaps malformed teeth with abnormal conical shape.
39
Q

What 4 steps come after tooth calcification

A
  1. calcification (1st X-ray crown appearance)
  2. Crown completion
  3. Root bifurcation
  4. Eruption
  5. Root completion
40
Q

What are the key dates for lower 6s

A
  • Calcification: just before birth
  • Crown completion; 3 years
  • Root bifurcation: 4.5 years
  • Eruption: 6 years
  • Root completion: 9 years
41
Q

What are the key dates for lower 7s

A
  • Calcification: 3 years
  • Crown completion: 6.5 years
  • Root bifurcation: 8.5 years
  • Eruption: 12 years
  • Root completion: 15 years
42
Q

Key eruption dates for incisors

A
  • Lower 1: 6-7 years
  • Lower 2: 7-8 years
  • Upper 1: 7-8 years
  • Upper 2: 7.5- 8.5 years
43
Q

Key eruption dates for canines and premolars

A
  • Lower 3: 9- 10 years
  • upper 3: 10-12 years
  • Lower & Upper 4: 10-11 years
  • Lower & Upper 5: 10.5 - 12 years
44
Q

There is no primary root absorption before what age

A

5 years. No shedding before then

45
Q

When do 6s, 7s, 8s calcify

A

just before birth
3 years
8-9 years

46
Q

Time between root resorption and exfoliation of primary teeth. (anterior and posterior) Time between clinical emergence and occlusion of permanent teeth (anterior and posterior)

A

anterior: 3 months
posterior: 6 months

anterior: 1 year
posterior: 1.5 years

47
Q

how long after eruption of incisors and molars, will the roots be complete

A

incisors - 2 years

molars - 3 years

48
Q

what is the canal called that teeth erupt in

A

gubernacular canal

Craniofacial & tooth biology (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions