Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
|
Placing Rubber Dam
|
Floss between contact
Select clamp and tie floss to it Try clamp around tooth Punch dam Place dam Ligate anterior tooth |
|
|
Define resistance form
|
- ‘Features of the cavity preparation which prevent fracture of the restoration or surrounding tooth tissue’
|
|
|
Define resistance form. Give two examples of how this may be implemented in a Class II cavity. (3 marks)
|
- Appropriate cavosurface angles
- Rounded internal line angles (eg. axiopulpal line angle) - Adequate cavity depth - Removal of plunger cusps - Cap/overlay of weakened cusps |
|
|
State the purposes of using a matrix and wedge during placement of a restoration in a Class II cavity
|
- Matrix: reproduction of natural contour
- Wedges: prevents gingival excess, separate teeth and compensate for the thickness of the matrix |
|
|
On what basis are composite resins classified? (1 mark)
|
Classified according to the average size of filler particles
|
|
|
Describe the setting reaction of a light-activated composite resin
|
Initiator (camphorquinone) is activated by light (470nm) to produce free fradicals which sets off polymerisation of the organic matrix
|
|
|
What type of material is best suited as a lining under composite resin?
|
Resin modified glass ionomer (RMGI) [vitrebond]
Possibly fast-set GIC (eg. Fuji IX for an open sandwich) |
|
|
State 2 reasons for placing a lining under a composite resin restoration
|
Seals the dentine tubules
Replaces lost dentine, decreasing shrinkage |
|
|
Explain how composite resin will be retained in cavities in 11 and 21
|
Micromechanical retention (etch 37% orthophosphoric acid)
Bevel |
|
|
The cavities in 14 and 24 will be filled with GIC Fuji IX
i. How is the material retained |
- Ion exchange bonding between polyalkenoic chain of glass ionomer and Ca+2 and PO43- ions of hydroxyapatite.
- H+ bond between carboxyl group of polyalkenoic chains and the collagen in dentine - Retentive design |
|
|
Describe the steps which must be taken to preserve the water balance of GIC Fuji IX from initial set to maturation. (2 marks)
|
Initial set to 24 hours → Sealing surface with unfilled resin protects from contact with water
1 day to 6 months/maturation → GIC is susceptible to dehydration |
|
|
List the advantages of rubber dam
|
Protect the airway
soft tissue control - improves access protection of soft tissues moisture control reduce bacterial contamination |
|
|
Describe the role and use of a matrix and wedge, in a class II amalgam resto
|
Contour
1. reproduce curvature of proximal surface 2. prevent overhang Contact 1. wedge separates teeth to compensate for thickness of matrix band |
|
|
What precautions are required to maximise the longevity of glass ionomer restorations?
|
Patient selection eg dry mouth, clean dentine surface (no plaque/pellicle selective smear layer removal)
Accurate powder/liquid ration Mixed as per manufacturer’s instruction Dentine ‘camp’, Neither wet nor desiccated GIC applied properly Still glossy Minimal handling/finished during initial set Adequate moisture protection in initial phase Protection from drying |
|
|
Patient with 4 occlusal caries and poor OH. What material do you choose and why?
|
Amalgam
|
|
|
What are the three aims of condensation of amalgam?
|
Adapt it to the cavity walls
Get rid of voids Expel excess mercury |
|
|
What are three limitations with finishing amalgam?
|
?
|
|
|
WHat composite would you avoid for a posterior resto?
|
Microfilled CR
|
|
|
Why is GIC considered a technique sensitive product?
|
It's longevity and effectiveness is governed by the operator's technique in preparation of the cavity for the GIC, the placement of the GIC and the ability of the operator to protect it from water absorption and later dehydration. Any failure in this process or over handling of the material will decrease it's longevity.
|
|
|
LIst the steps in placing a GIC resto to ensure maximum longevity?
|
Ensure the oral environment and cavity is suitable for a GIC restoration
Remove the smear layer on the dentine with dentine conditioner Ensure the cavity surface is moist (not wet or desiccated) Mix the GIC as per the manufacturer's instructions Apply GIC ensuring it is still glossy Minimal finishing with hand instruments during initial set Adequate moisture protection during initial phase Protection from dehydration |
|
|
What are the two goals of finishing amalgam?
|
Provide a smooth surface (minimising plaque retention)
Provide a surface composed principally of unreacted original alloy particles (most corrosion resistant |
|
|
What are the 4 ways to avoid gamma 2
|
High cu spherical
25% lathe High cu blend (Sn, Cu, Ag) High Cu blend (Ag-Cu) |
|
|
What is the amaglam setting reaction
|
y(Ag3Sn) + E(Cu3Sn) + Hg --> n' (Cu6Sn5) + y1(Ag2Hg23) + y + E {these two are unreacted alloy}
|
|
|
What happens if amalgam is moisture contaminated during condensation?
|
All amalgams tarnish and corrode
Zn containing amalgams also experience excessive delayed expansion (Zn scavenger for O2) |
|
|
What are the three steps in the setting reaction of GIC
|
Dissolution
Precipitation Hydration |
