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Perio II > Crown Lengthening > Flashcards

Crown Lengthening Flashcards

1
Q

what are the indications for functional crown lengthening

A
  • subgingival restorative margins
  • tooth fracture
  • endodontic perforations
  • cervical root resorption
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2
Q

what are the indications for esthetic crown lengthening

A
  • excessive gingival display
  • gingival overgrowth (from medications)
  • altered passive eruption
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3
Q

what is the supracrestal attachment number

A

2.04mm

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4
Q

what is the supracrestal attachment made of

A
  • CT: average of 1.07mm
  • junctional epithelium: 0.97mm
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5
Q

which part of the supracrestal attachment is more variable

A

the JE

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6
Q

what are the indications for crown lengthening

A
  • to allow for restoration of tooth (caries removal, clamp placement)
  • increasing crown length for retention of restoration (adequate ferrule)
  • restoration of tooth in harmony with supracrestal attached tissue (biologic width)
  • esthetics via alteration of the gingival labial profile
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7
Q

what is a ferrule

A

the vertical axial wall that surrounds the tooth

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8
Q

when is the ferrule needed

A

every time a crown is fabricated to help resist fracture and/or crown displacement

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9
Q

how much ferrule do you need

A

at least 2mm of ferrule (natural tooth structure) circumferentially, beyond the core

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10
Q

what are the considerations and limitations for crown lengthening

A
  • is the tooth restorable
  • is the tooth strategically important
  • prognosis
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11
Q

what is considered in if the tooth is restorable

A

caries removal is done

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12
Q

what is considered in “is the tooth strategically important”

A
  • opposing tooth
  • position in the arch
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13
Q

what is considered in the prognosis of crown lengthening

A
  • amount of tooth remaining in supporting bone
  • furcations
  • mobility
  • esthetic concerns
  • thick or thin phenotype
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14
Q

when are the caries removed and when is the provisional crown done in relation to crown lengthening

A

before surgery

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15
Q

when is the final restoration placed after crown lengthening

A

variations between 6 weeks and 6 months but not sooner than that

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16
Q

if you are in doubt how long should you provisionalize the tooth after crown lengthening

A

3-6 months

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17
Q

in health the CEJ should be _____ from osseous crest

A

2mm

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18
Q

in health the gingival margin should be _____ coronal to the CEJ

A

0.5-2mm

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19
Q

describe active eruption

A
  • as the tooth breaks through the gingiva it erupts until it meets its antagonist and occlusion
  • eruption then ceases or slows
  • eruption potential continues throughout life
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20
Q

what is passive eruption

A

apical shift of the dentogingival junction
- occurs during and after active eruption
- tooth does not move, gingiva does (apically)

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21
Q

what are the stages of passive eruption

A
  • junctional epithelium rests on enamel surface
  • JE rests on enamel and cemental surface apical to CEJ
  • epithelial attachment rests on cementum
  • epithelial attachment migrates apically
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22
Q

when does passive eruption conclude

A

when sulcus base is at level of the CEJ placing the gingival margin 1-2mm coronal to the CEJ

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23
Q

what is altered active eruption and what is it exacerbated by

A
  • morphological variant where CEJ is less than 2mm from osseous crest
  • can be exacerbated by orthodontic brackets
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24
Q

what is altered passive eruption and what is it exacerbated by

A
  • morphological variant where gingiva is more than 2mm coronal to the CEJ
  • can be exacerbated by inflammation and medications
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25
Q

what is altered passive eruption

A

when eruption does not progress past stage 1 or stage 2

26
Q

what is the frequency of altered passive eruption in adults

A

12%

27
Q

normal passive eruption may continue throughout:

A

the teen age years

28
Q

why may gingiva be present on the crown of the tooth in adolescents

A

because the dentogingival unit has not fully receded to its final position

29
Q

when do anterior teeth typically undergo passive eruption

A

in the early teen years

30
Q

the posterior teeth can continue to undergo passive eruption into:

A

a patient’s 20’s

31
Q

does everyone have the same supracrestal attachment

A

no

32
Q

what are the 3 categories of supracrestal tissue attachment and their prevalence

A
  • normal crest- 85% of the time
  • high crest: 2% of the time
  • low crest: 13% of the time
33
Q

what are the 2 categories of low crest

A

stable and unstable

34
Q

describe the normal crest

A
  • bone sounding 3mm from gingival crest to alveolar crest midfacial
  • 3-4.5mm from gingival crest to alveolar crest at line angles
35
Q

describe the high crest

A
  • bone sounding less than 3mm from gingival crest to alveolar crest midfacial
  • less than 3mm from gingival crest to alveolar crest at line angles
36
Q

describe the low crest

A
  • bone sounding greater than 3mm from gingival crest to alveolar crest midfacial
  • greater than 4.5mm from gingival crest to alveolar crest at line angles
  • sulcus must be probed in order to determine sulcus depth in addition to bone sounding
37
Q

describe the unstable low crest

A
  • normal attachment apparatus (2mm)
  • greater than normal sulcus depth
  • prone to recession due to the deeper sulcus depth and unsupported gingival crest
  • only category in which a gingivectomy alone is successful
38
Q

describe the stable low crest

A
  • normal sulcus depth
  • longer than normal attachment apparatus
  • susceptible to gingival rebound after crown lengthening due to inadequate ostectomy to accomodate the longer attachment apparatus
39
Q

what are the components of an appealing smile

A
  • teeth: size, shape and position
  • gingival scaffold: health and contour
  • lip framework: shape, length and mobility
  • skeletal profile
  • eyes
40
Q

what is a perfect smile clinically

A
  • show 75-100% of crowns and interproximal gingiva
  • symmetrical display and harmony between the maxillary gingival line and the upper lip
  • lower lip parallel to the incisal edges of maxillary teeth and in close approximation
41
Q

what creates facial harmony

A

parallelism between interpupillary line and commissural line creates facial harmony

42
Q

what is the smile line

A

position of the upper lip relative to the maxillary incisors and gingiva during a natural full smile

43
Q

what is the normal tooth length of the central incisor, lateral and canine

A
  • central: 11-13
  • lateral: 10
  • canine: 11-13
44
Q

what is the minimum tooth length for centrals, laterals and canines in order to still be considered normal

A
  • central: 10mm
  • lateral: 9mm
  • canines: 10mm
45
Q

what is the preferred anatomical crown width to height ratio

A

78%

46
Q

what is the acceptable range of anatomical crown width to height ratio

A

66-80%

47
Q

does the anatomical crown height depend on race or gender

A

no

48
Q

central incisor width is ______ than the lateral incisor

A

60% wider

49
Q

the lateral incisor width is ______ than the mesial portion of the canine

A

60% wider

50
Q

if you assign the value of 1.0 to a lateral incisor then the central incisor would be _____ the width of the lateral incisor

A

1.6x

51
Q

if you assign the value of 1.0 to a lateral incisor then the canine would be _____ the width of the lateral incisor

A

0.6x

52
Q

what would be the indications for a gingivectomy only

A

thick tissue and deep pockets

53
Q

when would the tissue relapse after a gingivectomy

A

if the bone is too overgrown too and you dont reduce the bone

54
Q

what is the gingival zenith of the centrals, laterals, and canines

A
  • centrals:1 mm distal to midline
  • laterals: 0.3mm distal to midline
  • canines: centered MD
55
Q

describe the gingival margin of the anterior teeth

A
  • central and canine ON SAME LINE
  • lateral 0.5-1.0mm coronal to central and canine
56
Q

what should you do to help determine classification and treatment

A
  • perform detailed smile analysis
  • look at amount and location of keratinized tissue
  • evaluate location of supporting bone using radiographs and/or bone sounding with LA
  • understand where the CEJ is located
  • understand the clinical vs anatomic size of the teeth
57
Q

what 2 criteria must be met to diagnose altered passive eruption

A

-the tooth is short by measurement
- the CEJ cannot be detected in the sulcus with the tip of the exploreer

58
Q

what are the treatment goals for an esthetic smile

A
  • thin and move the alveolar bone 2mm apical to the CEJ from facial line angle to facial line angle
  • position the gingival crest 3mm coronal to the new alveolar crest position
  • level the tissue at the new position
59
Q

what is the surgical technique to do an ostectomy

A
  • sulcular incisions
  • extend incisions to mesial of second molar (most of the time)
  • thin the papilla
  • apically position the flap (instead of removal of a collar of tissue)
  • create the ostectomy with parallel sides that are positioned toward the interproximal areas
60
Q

what are the post operative instructions after osteoctomy

A
  • do not do anything to activate the lower lip such as sucking through a straw, kissing or pulling the lip up to look at the surgical site
  • no brushing anywhere for 4 days
  • no brushing of the maxillary arch for 2 weeks
  • rinse twice daily with an antimicrobial rinse for 2 weeks
61
Q
A

Perio II (6 decks)

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