exam 2 (L11) - clinical crown lengthening

Question 1

define clinical crown lengthening (CCL).

Answer 1

a surgical procedure designed to increase the extent of supragingival tooth structure for restorative or esthetic purposes by apically positioning the gingival margin, removing supporting bone, or both

Question 2

concepts of crown lengthening

Answer 2

• anterior esthetics:
  + gummy smile
  + gingival line symmetry
  + short front teeth
• cervical caries or fracture lines

Question 3

if pt has excessive gingival display, what is the indication and contraindication for CCL?

Answer 3

indicated: not enough of clinical crown displayed

- contraindicated: hypermobile lip, skeletal problem

Question 4

at what measurement (from CEJ to FGM) can passive eruption cause an asymmetrical appearance of teeth?

Answer 4

> 2 mm

Question 5

if patient presents with skeletal defect that causes an asymmetrical smile, what can be done to correct it?

Answer 5

oral surgery; do NOT do CCL

Question 6

Please give a riveting laundry list of anterior aesthetic considerations.

Answer 6

• facial symmetry
• interpupillary line
• smile line: low, medium, high
• dental midline
• gingival display
• harmony of gingival margins
• gingival margins relative to CEJ
• tooth size/proportions
• incisal/occlusal plane

Question 7

for lateral incisors, how much more coronal/incisal should the gingival margin be than for the adjacent centrals?

Answer 7

0.5 mm coronal/incisal

Question 8

if deep caries or inadequate height are present before crown placement, how does CCL help?

Answer 8

• good crown margins
• good impressions with defined prep margins
• gingival health during provisionalization and after final restoration
• aids: adequate crown height, retention, and emergence profile

Question 9

what is the biologic width from alveolar crest to CEJ?

Answer 9

• 2 mm (JE + CT)

- entire dentogingival complex (include sulcus) is 3 mm

Question 10

what 2 problems will occur if biologic width is encroached upon during crown placement?

Answer 10

• gingival recession

- chronic inflammation

Question 11

what is optimal distance from gingival margin to alveolar crest? from sound tooth structure (cavosurface margin) to alveolar crest?

Answer 11

• 3 mm

- at least 4 mm

Question 12

what is “sounding” bone?

Answer 12

under local anesthesia, penetrate JE till you reach alveolar crest so you know pt’s BW

Question 13

what are the 3 objectives of crown lengthening?

Answer 13

• maintain healthy dentogingival junction PDL
• improve esthetics
• improve access and retention for restoration

Question 14

what are the 3 approaches to CCL?

Answer 14

• gingivectomy with no osseous surgery (external VS internal bevel)
• apically positioned flap with no osseous resection
• apically positioned flap with osseous resection

Question 15

in what state does an externally beveled gingivectomy leave the gingiva? indications and contraindications?

Answer 15

• open wound that requires secondary intention healing
• indications = enough keratinized tissue, BW post-op
• contraindications = not enough keratinized, BW invasion

Question 16

when should you do a gingivectomy for CCL?

Answer 16

• external: no bony involvement, remove excess KG

- internal: bony involvement/close to crest, remove excess KG

Question 17

in what state does internally beveled gingivectomy leave the gingiva? indications and contraindications?

Answer 17

• wound can be closed to heal by primary intention
• indications = enough keratinized G, BW post-op
• contraindications = not enough KG, BW invasion

Question 18

what are the two types of incisions for gingivectomy?

Answer 18

• externally beveled (simply for excess tissue)

- internally beveled (more conservative, bony involvement)

Question 19

what are the 3 flap types available, when are they used, and what kind of incisions are available for use with them?

Answer 19

• modified Widman flap:
  + only fold slightly past the alveolar crest
  + cannot apically reposition gingiva
  + used for accessing roots for various procedures
  + has small incisions for SRP & curettage
• partial thickness flap:
  + increase amount of keratinized tissue b/c it grows back bigger when periosteum is not exposed
  + can apically reposition gingiva
  + can use sulcular (coronal or reposition) or scalloped (palatal or apical positioning)
• full thickness flap
  + used whenever you want to access bone
  + can use sulcular or scalloped incision

Question 20

how well does apically positioned flap without osseous resection work?

Answer 20

it doesn’t, because the tissue will simply grow back if the bone remains in place (tissue rebound)

Question 21

when is osseous resection performed concurrently with an apically positioned flap? what incision options do you have?

Answer 21

• when need to establish BW
• submarginal (scalloped) = when adequate KG present
• sulcular w/ apical position = when little KG

Question 22

what is the golden proportion of esthetics?

Answer 22

• anterior teeth have a width:length ration of 0.8
• from frontal plane, W:L = 0.618
  + laterals narrower than centrals
  + canines narrower than laterals
  + canines > premolars

Question 23

how long should you wait after crown lengthening to place the final crown?

Answer 23

at least 6 weeks