Q6-Developing Posterior Contours Flashcards

1
Q

The biological contours help to achieve these goals involving the teeth and tissues

A

stimulate natural, healthy gums
protect supporting tissues
maintain the health of the gingiva and attachments
minimize trauma and irritation to bony tissues

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2
Q

Improper contours can result in these issues

A

often induce early breakdown of supportive structures

result in early loss of teeth

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3
Q

The facial and lingual convexities relate to this

A

crest of curvature = height of contour

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4
Q

Where is the greatest convexity (or bulge) of the crown

A

on the axial surfaces

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5
Q

When viewed from the medial or distal, crowns have rather uniform curvatures in which areas

A

cervical third and in the middle thirs

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6
Q

The proper degree of curvature will do what

A

deflect food over the gingival margin preventing irritation

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7
Q

True or False

The proper curvature will allow some stimulation of soft tissue

A

True; massaging of the gingiva while chewing will help to stimulate the soft tissues

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8
Q

What will happen if the proper curvature is absent

A

the gingival tissue will be drivel apically and this will result in pathological changes

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9
Q

What will happen if the proper curvature is too great

A

The gingiva will be protected too much and lose its gingival tone
food and debris may pack under the area and result in chronic inflammation of the gingiva

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10
Q

Where is the facial height of contour

A

in the cervical third

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11
Q

What is the dimension of the facial height of contour

A

no more than 1/2 mm facially beyond the CEJ

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12
Q

Where is the lingual height of contour

A

in the middle third

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13
Q

What is the dimension of the lingual height of contour

A

no more than 1/2 mm lingually beyond the CEJ

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14
Q

What are the exceptions to the lingual height of contour

A

mandibular second premolars and molars
they extend 3/4 to 1 mm lingual
due to the lingual tilt

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15
Q

What is the emergence profile

A

tooth surface that is gingival to the height of contour and above the gingival crest

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16
Q

What describes the angle of the emergence profile

A

the profile of the gingival third of a restoration as it emerges from the gingival crevice

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17
Q

Where is the area of the emergence profile

A

should be flat for 2-3mm above the gingiva

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18
Q

Due to the interdental papillae, what does this do for the proximal surfaces

A

proximal surfaces are ALWAYS flat or slightly concave between the contact area and CEJ to allow room for the papillae

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19
Q

What is the contact area of a tooth

A

the area of the mesial or distal surface of a tooth which touches its neighbors
similar to a ball or ball point contact
can have various locations

20
Q

What are the 4 basic functions of a contact area

A

aids in proper development of the arches
prevents food from packing between the teeth
allows teeth to be self cleaning
prevents injury to the interproximal tissues

21
Q

True or False

The contact areas become contact points as we age

A

False; the contact POINTS become contact AREAS as we age

22
Q

What causes the contacts to become more broad

A

due to wear as the teeth move during function

23
Q

Contact area of all posterior teeth should be where

A

buccal to the central fossa and in the occlusal third

24
Q

What is the exception to having the contact in the occlusal third

A

between maxillary molars

in the junction of the occlusal and middle third or middle third

25
Q

What is the exception to having the contact buccal to buccolingual center

A

between maxillary molars; in the middle third (large lingual)

26
Q

True or False

Mesial contacts are more cervical than distal contacts

A

False; distal contacts are more cervical than mesial contacts

27
Q

What is the only tooth where the mesial contacts are more cervical

A

mandibular first premolar

28
Q

Where would you find the axial transitional line angle

A

between the faciolingual convexities and proximal concavities

29
Q

Improper transitional line angles can present what

A

a hazard to the supporting tissues

30
Q

True or False

Transitional line angles are straight between the proximal contact point and the CEJ

A

True

31
Q

This is on the occlusal surfaces of the teeth at the proximal border; a ridge like structures neighbored by two depressions

A

marginal ridges

32
Q

What forms a marginal ridge

A

two depressions; occlusal embrasure and proximal fossa

it is concave in shape

33
Q

Marginal ridges have what type of crests, are shaped which ways MD/FL, and the adjacent ridges relate how

A

rounded elevated crests
convex MD
concave FL
adjacent ridges are at the same height (opposing cusp to contact)

34
Q

What are the exceptions to a normal marginal ridge

A

premolars and canines

35
Q

Marginal ridges converge from ______ to _______

A

buccal to lingual (buccal 1/2 wider than lingual 1/2)

36
Q

In which tooth is it not true that the facial is wider than the lingual

A

maxillary first molar

37
Q

What is an embrasure space

A

The ā€œVā€ shaped space extending outward from the contact area of the teeth
also known as a spillway space

38
Q

What are the 2 main functions of the embrasure space

A

a spillway for the escape of food during function

helps to keep the teeth clean

39
Q

Which embrasure space is always larger, buccal or lingual

A

lingual space is always larger

40
Q

Cervical curvature/cervical line extends where

A

it curves occlusally at the proximal and apically at the facial and lingual

41
Q

What does the cervical curvature relate to

A

the contour of the bony alveolar bone

42
Q

If the cervical margin is within this distance to the alveolar bone, then the bone will begin to recede

A

1.5-2.0mm

43
Q

An over-contoured crown results from what and causes what

A

inadequate tooth reduction and it can cause a lack of room for biomaterials

44
Q

What can result if a margin of a restoration is placed subgingival

A

inflammation and reduction of gingival height

45
Q

When placing a sub gingival margin it is wise to use what material

A

a metal margin; it is easily tolerated by the tissues

46
Q

True or False

It is important to always establish contours in restorations which are in harmony with the natural tooth structure

A

True