Impression techniques and soft tissue management Flashcards
β What are the principles of managing periodontal tissue when planning extra-coronal restorations?
Establish periodontal health for clinical success πͺ
Design restorations to allow for plaque control π¦·π§Ό
Avoid iatrogenic damage π«π
Why must gingiva be healthy before starting extra-coronal restorations?
Proves patient motivation π‘
Stabilizes gingival margins β
Facilitates easier preparation & impression taking ποΈ
Inflamed gingiva bleeds easily on touch π©Έ
Swollen gingiva hinders access π·
Poor oral hygiene β‘οΈ gingival recession β‘οΈ visible crown margins π¬
How can you establish gingival health before restorations?
Oral hygiene instruction (OHI) and patient motivation πͺ₯π¬
Remove plaque-retentive factors (PRFs) π§½
Remove calculus and overhanging restorations π¦·
Provide temporary crowns (chairside/lab-made) π
No bleeding on probing or marginal bleeding π«π©Έ
How should a restoration be designed to promote gingival health?
Facilitate plaque removal and discourage accumulation π§Ό
Consider margin position π
Material selection πͺ¨
Embrasure spaces and contour π―
What are the 3 types of margin positions?
Subgingival β¬οΈ
Juxta-/Equigingival π°
Supragingival β¬οΈ
When would a subgingival margin be indicated?
Caries extends into gingival crevice π¦
Need for increased retention π
Existing restoration is already subgingival π
Dentinal hypersensitivity π§π¦·
Aesthetic demands (patient or dentist) π
Subgingival fracture of the tooth π¬
How can you minimise the negative effects of subgingival margins?
Optimal gingival health beforehand π¦·πΏ
Minimal gingival trauma β
Gentle retraction cord use π§΅
Take sulcus impression immediately after cord removal π©Ή
Use well-fitting, properly contoured provisionals π
Observe oral hygiene post-placement ππͺ₯
Why is restoration contour critical for gingival health?
Must allow for optimum plaque control π§Ό
Excessive bulk in gingival third β plaque buildup π«
Excess contour does not protect gingiva
Precision tooth prep is essential for proper contour βοΈ
β What is the aim of a master impression?
To capture an accurate, dimensionally stable, and fully supported impression of the prepared teeth and soft tissues π―π¦·
What factors influence a successful impression?
Right impression tray πͺ£
Proper choice & handling of materials π§ͺ
Field control π
Patient management π
Accurate impression assessment π
Labelling, disinfection, transport & storage π§Όπ¦
Accurate impression casting π§
What is required when capturing a subgingival margin in impressions?
Clear visibility of entire margin ποΈ
Subgingival margins = require soft tissue management π§΅π©Έ
What are the methods of soft tissue management for impressions?
Retraction: Cord or retraction paste π§΅π§΄
Removal: Rotary curettage, electrosurgery, or laser π¨π¬
Bleeding control: Haemostatic agents π§ͺ
What are the advantages and disadvantages of retraction cords?
Advantages:
Universal technique π
Varying degrees of retraction possible π
Inexpensive π·
Single/double cord techniques π―
Disadvantages:
Can cause bleeding π©Έ
Painful for the patient π£
Time-consuming β³
Risk of recession if epithelial attachment is damaged β οΈ
What precautions should be taken with retraction cord use?
Cords have colour/number codes for size identification π¨π’
Healing occurs within days if epithelial attachment is severed carefully π οΈ
Longer cord time = higher chance of adverse effects π
Removing dry cord can tear epithelium β‘οΈ recession π¬
Always document cord removal β
π
How is bleeding controlled during impressions?
Haemostatic agents π§ͺ
Pressure from cord/putty π§΅
Electrocautery β‘
Compare different haemostatic agents:
Aluminium chloride (pH 3) β least reactive with impression materials π‘
Ferric sulphate (1.2%) β stains tissue black, may inhibit impression set π€
Aluminium sulphate (pH 3) β offensive taste π
Adrenaline (pH 7) β hard to dose, can increase heart rate πβ οΈ
What is a retraction paste, and how is it used?
Injectable paste for sulcus retraction π
Keeps field dry βοΈ
Often contains aluminium chloride to control bleeding π§ͺ
Applied for 1β2 mins then rinsed away πΏ
What are the pros & cons of electrosurgery for soft tissue removal?
Pros:
Great haemostasis if tissue isnβt inflamed π©Έ
Cons:
Risk of gingival recession π·
Contraindicated for pacemaker users β οΈ
Cannot use plastic instruments π§΄
How do you assess an impression effectively?
Start with full view, then zoom in π
Dry it and use good lighting π‘
Check for:
All teeth in the arch π¦·
Tray showing through? β
Air blows that affect articulation? π¨
Material stuck to tray? π§½
Prep margins all visible? π§
No drags or voids π«
Adjacent/contralateral teeth visible? β
Which parts of the restoration process can affect gingival health?
Provisional restoration ποΈ
Final restoration and its design π§±
Cementation technique and material π§ͺπ§½
How do provisional restorations impact gingiva?
Poor fit = plaque retention hotspot π¦
Should be used for the shortest time β³
Marginal finish & polish are crucial β¨
Why is the fit of a crown critical?
Poor fit = periodontal disease risk π§«
Defective margins linked with alveolar bone height reduction π
How does surface smoothness affect tissue response?
Roughness aids plaque build-up π¬
Highly polished gold works well β¨
Gingiva prefers ceramic πͺ¨
Composite resin = more issues π«
How should margins be finished for optimal gingival health?
Even experienced clinicians can miss 120ΞΌm gaps π
Aim for the thinnest cement layer possible π
Ensure proper taper and eliminate irregularities π―
