Impression Techniques and Soft Tissue Management

Question 1

list the Principles of managing the periodontal tissues
when planning extra coronal restorations

Answer 1

*Establish health for clinical success
*Design restorations to allow control of plaque
*Avoid iatrogenic damage

Question 2

Gingiva must be healthy before
embarking on extra coronal restorations

why?

Answer 2

*Prove motivation
*Stable gingival margin
*Facilitates preparation and impression taking

Question 3

Gingiva must be healthy before embarking
on extra coronal restorations

how?

Answer 3

Question 4

In terms of restoration design, it should aim to facilitate plaque removal and discourage
plaque accumulation

what sort of aspects of restoration design are important in doing so?

Answer 4

*Margins
*Material
*Embrasure spaces
*Contour

Question 5

In terms of crown margin, what are our 3 choices?

Answer 5

• Subgingival
  *Juxta or Equigingival
• Supragingival

Question 6

Margin Position
It has been shown that in
…..% of people the gingival
aspect of their anterior
teeth does not show
during smiling

Answer 6

33

Question 7

what are the certain circumstances we would you place a subgingival margin?

Answer 7

*Caries into the gingival crevice
*Increase retention
*Existing restoration is subgingival
*Dentinal hypersensitivity
*Aesthetic demands of the patient and
dentist
*Subgingival fracture

Question 8

how do we Minimise the effect of subgingival
margin placement?

Answer 8

*Optimal pre prosthetic gingival health
*Minimal gingival trauma
*Careful use of retraction cord
*Sulcus impression after impression removal
*Well fitting properly contoured provisional
restorations
*Post placement observation of hygiene
measures

Question 9

what are the requirements of the restoration contour?

Answer 9

*Contour must allow for optimum plaque
control
*Excessive bulk in the gingival third leads to
plaque accumulation. It does not protect the
gingivae as previously thought
*In essence precise preparation of the tooth
is required

Question 10

what is the Purpose of master impressions

Answer 10

To obtain an accurate, dimensionally stable, fully supported impression of the prepared teeth…..
and associated soft tissues.

Question 11

What steps are needed to ensure a good
impression and outcome?

Answer 11

*Choice of impression tray
*Choice and handling of the impression material
*Control of the field
*Management of the patient
*Accurate assessment of the impression
*Handling of the completed impression –
labelling, disinfection, transport, storage
* Impression casting

Question 12

what are the 2 ways we can manage soft tissues before taking an impression?

Answer 12

retraction of tissue

removal of tissue

(control bleeding in both situations)

Question 13

before taking an imp, how can we retract tissue?

Answer 13

*Cord (single/twin)
*Paste

Question 14

before taking an imp, how can we remove tissue?

Answer 14

*Rotary Curettage
*Electrosurgery
*(Lasers)

Question 15

list the adv of a retraction cord

Answer 15

*Universal technique
*Various degree of
retraction possible
*Cord is inexpensive
*Double or single cord
techniques possible

Question 16

list the disadv of a retraction cord

Answer 16

*Can cause bleeding
*Painful ??
*Time consuming
*Epithelial attachment
can be damaged
leading to recession

Question 17

Answer 17

Question 18

list the different ways of control of bleeding

Answer 18

*Haemostatic agent
*Pressure effect of cord/putty
*Electrocautery

Question 19

a gingival retraction cord is only used with

a)supragingival margins
b) subgingival margins

Answer 19

b

Question 20

list some of the common haemostatic agents that may form part of the retraction paste or could be used to soakl the cord before placement

Answer 20

Question 21

how should ferric sulphate be used in order to control bleeding?

Answer 21

• on a microbrush
• wrapped around gingival crevice
• by doing this we are pushing it into those exposed blood vessels and causing clotting of top part to stop further bleeding from happening

Question 22

haemostatic agents - disadvantage of Aluminium Chloride?

Answer 22

Least reactive with
addition cured silicone impression materials

Question 23

haemostatic agents - disadvantage of *Ferric Sulphate?

Answer 23

turns tissues black, bleeding
on cord removal and can inhibit set of
impression material

Question 24

haemostatic agents - disadvantage of Aluminium Sulphate?

Answer 24

has an offensive taste

Question 25

haemostatic agents - disadvantage of *Adrenaline?

Answer 25

difficult to control the dose and can increase heart rate

Question 26

if there isnt any bleeding, we dont actually need a haemostatic medicament. what do we place on the cord instead?

Answer 26

water - so not dry when you shove it down

Question 27

describe retraction paste

Answer 27

*Injectable paste for gingival retraction *Opens the gingival sulcus but leaves the field dry

Question 28

what substance may a retraction paste contain to control bleeding?

Answer 28

Aluminium Chloride

Question 29

retraction paste is placed for .... to .... mins then rinsed

Answer 29

1-2 mins

Question 30

adv of electrosurgery?

Answer 30

*Post surgical haemorrhage is well controlled provided that the tissue is not inflamed

Question 31

disadv of electrosurgery?

Answer 31

*Potential for recession after treatment *Pacemakers *Plastic instruments

Question 32

in terms of assessing the crown impression, list the things we are looking for

Answer 32

Question 33

What other aspects of extracoraonal restorations treatment may impact on gingival health?

Answer 33

*Provisional restorations *The restoration *Cementation *The final restoration *The restoration *Cementation

Question 34

Provisional Restorations - Plaque retention very high/low?? with these materials

Answer 34

high

Question 35

Provisional Restorations -Place for the minimum / maximum?? time possible

Answer 35

maximum

Question 36

fit of crown - is there a correlation between poor fit and periodontal dx?

Answer 36

yes Association between defective crown margins and a reduction in the height of interdental alveolar bone has been demonstrated

Question 37

if the roughness of marginal interface of the crown doesnt directly irritate tissues, why is it bad?

Answer 37

allows plaque to accumulate

Question 38

*Highly polished gold/silver/titanium?? is the best interface but gingival tissue responds well to ceramic

Answer 38

gold

Question 39

finish of crown margins - list what we're looking for

Answer 39

*Visible inspection (NB Difficult with subgingival margins). Most experienced operators can miss marginal gap of at least 120μm *Closest possible fit with thinnest layer of cement visible *Proper taper with no irregularities, which can prevent proper seating

Question 40

list important aspect of cementation we need to watch out for

Answer 40

*Do not overfill the crown with cement *Use of microbrush to load *Make sure you are familiar with working and setting times/techniques *Carefully check gingival sulcus for residual cement *Knotted floss