FIXED PROS - Impressions and Soft Tissue Management

Question 1

when planning extra coronal restorations, how should the tissues be considered?

Answer 1

• good health for clinical success
• restorations designed to allow plaque control
• avoid iatrogenic damage

Question 2

why must the gingiva be healthy before placing an extra coronal restoration?

Answer 2

• stable gingival margin
• easy to prepare and impression taking
• patient will have good motivation for good oral hygiene

Question 3

how is good periodontal care established?

Answer 3

• OHI
• patient motivation
• remove PRF - calculus, overhangs, temp crowns
• no BOP

Question 4

what 4 things must be considered with restoration designs?

Answer 4

• margins
• material
• embrasure spaces - like my front teeth
• contour

Question 5

what are the 3 margins to consider?

Answer 5

• subgingival
• supragingival
• equigingival - remaining even with the tissue to place the margin

Question 6

6 reasons why you may want to place a subgingival margin?

Answer 6

• to not interfere or damage the natural gingival tissue
• to discourage plaque accumulation by not leaving an edge by the gingival crevice
• increase retention
• improves aesthetics
• to protect against dentinal hypersensitivity
• if there is a subgingival fracture

Question 7

how can you minimise the effect of subgingival margin placement?

Answer 7

• use of retraction cord
• take a sulculus impression
• restorations must be well-fitted and contoured
• good hygiene observation

Question 8

what is a gingival retraction cord?

Answer 8

a absorbent string inserted into the gingival crevice to provide mechanical tissue displacement

Question 9

why must the contour be considered? (2)

Answer 9

• plaque control
• excessive bulk in gingival third = plaque accumulation

Question 10

what is the purpose of taking an impression?

Answer 10

to obtain:
- accurate
- dimensionally stable
- fully supported impression

of prepared teeth and associated soft tissues

Question 11

what has to be considered for a good impression?

Answer 11

• choice of tray
• choice of material
• moisture control
• handling of material and completed impression - label, disinfect, transport, storage
• managing the patient
• accurate assessment of impression
• casting

Question 12

3 ways the soft tissue is managed.

Answer 12

• retract the tissue
• remove the tissue
• control bleeding

Question 13

two ways in which you can retract the gingival tissue.

Answer 13

retraction cord
astringent retraction paste

Question 14

how is gingival tissue removed?

Answer 14

• rotary curette - not recommend, uncomfortable and bleeding
• electrosurgery
• laser

Question 15

state 4 advantages to using a retraction cord and 4 disadvantages.

Answer 15

advantages
- universal technique
- various degrees of retraction are possible
- cheap
- double or single cord available

disadvantages
- bleeding
- painful
- time consuming
- can damage the epithelial attachment, lead to recession

Question 16

describe the double cord/twin cord technique

Answer 16

one chord placed deep
another chord placed on top and removed just before impression taken

• usually with triple 0 chord

Question 17

is there a relationship for a retraction cord and potential for adverse reactions?

Answer 17

yes, direct link
esp more if it is dry

Question 18

what must you note down regarding the retraction cord?

Answer 18

that is has been used
that is has been removed

Question 19

how may bleeding be controlled?

Answer 19

• electrocautery
• pressure effect from cord/putty
• haemostatic agent (astringents)

Question 20

give 4 haemostatic agents (astringents) which can be used to control bleeding. describe: the pH they work at and how they work

Answer 20

1. ferric sulfate
   pH 1.2
   cauterizes tissues
2. aluminium chloride
   pH 3
   constricts tubules
3. aluminium sulfate
   pH 3
   constricts tubules
4. adrenaline
   pH 7
   vasoconstrictor

Question 21

how is ferric sulfate astringent used?

Answer 21

rub on gingival margin using microbrush
wash away black bits before placing cord

Question 22

which astringent:
1. is the least reactive with silicone impression materials?
2. turns tissues black?
3. bleeds on cord removal?
4. can inhibit the setting of impression?
5. has an offensive taste?
6. is difficult to control the dose and can increase heart rate?

Answer 22

1) aluminium chloride
2) ferric sulfate
3) ferric sulfae
4) ferric sulfate
5) aluminium sulfate
6) adrenaline

Question 23

give an advantage to using electrosurgery and 3 disadvantages.

Answer 23

advantage
- post surgical haemorrhage is well control if the tissue is not inflamed

disadvantages
- recession potential
- pacemakers - electrocautery can mimic programming signal and cause device to be reprogrammed
- plastic instruments to be used to not conduct electricity

Question 24

what needs to be considered when assessing the impression?

Answer 24

• assess when it is dry
• all teeth present?
• areas where tray is showing?
• any air blows?
• prep - visible margins? detail of each tooth? shapes of each tooth?

Question 25

why can provisional restorations affect the gingival health?

Answer 25

• always a gap present - PRF
• needs to be finished, surface roughness - PRF

Question 26

is there a relationship between fit of the crown and periodontal disease?

Answer 26

yes, direct correlation
- defective crown margins and reduction interdental alveolar bone

Question 27

what is the ideal finished margin?

Answer 27

• closest possible fit
• thinnest layer of cement visible
• taper with no irregularities, irregularities prevent proper seating

Question 28

what is the least marginal gap most operators miss by?

Answer 28

120μm