BDS2 CDS Operative Techniques > Op Tech Revision Notes > Flashcards

Op Tech Revision Notes Flashcards

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1
Q

what 3 things determine cavity design?

A
  • structure/properties of dental tissues
  • disease (caries/periodontal/tooth surface loss)
  • properties of matierals
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2
Q

when carrying out a cavity there is a strong relationship between which 4 factors?

A
  • position of caries
  • extent of caries
  • shape of prepared cavity
  • final restorative material
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3
Q

what are the 4 categories for the position of caries?

A
  • pits and fissures
  • approximal (posterior, anterior)
  • smooth surface (erosion /abrasion/ abfraction/ hypoplasia)
  • root
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4
Q

when to operatively intervene?

A
  • when a lesion is cavitated
  • when patient can’t access lesion for prevention

consider when:

  • lesion is into dentine radiographically
  • lesion is causing pulpitis
  • lesion is unaesthetic
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5
Q

if there is an enamel fracture when should it be removed?

A

when the enamel fracture is along prisms, there is unsupported enamel and/or under occlusal load should be removed before restoration

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6
Q

what happends to gingival tissues in the presence of plaque?

A

they become inflamed

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7
Q

consideration for restoration margin

A

should be easy to clean

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8
Q

where are enamel side cut prisms

A

on the wall

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9
Q

where are enamel end cut prisms

A

on the floor

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10
Q

what are the tubules like in primary dentine?

A

open

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11
Q

what are the tubules like in tertiary dentine?

A

irregular structure

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12
Q

what are 6 dentine considerations in op tech?

A

1/2/3

intra/inter/peri tubular

Diameter

Density

contents /mineralisation

healthy/diseased/reactive

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13
Q

what are necessary cavity finishings required?

A
  • maximising adhesion
  • occlusal relationships
  • ease of patient cleaning
  • properties of materials used
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14
Q

resistance of dentine and enamel to fluoride caries

A
  • enamel is resistant (high modulus of elasticity)

- dentine is not (low modulus of elasticity

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15
Q

times for acid-etching

A

20 secs on enamel
- more mineralised/less water

10 secs on dentine

  • less mineral
  • highly porous
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16
Q

where is a point of weakness in a cavity?

A

where 2 things interface

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17
Q

when only should healthy tissue be removed?

A
  • Material used requires it
  • Margins of cavity are in contact with another tooth
  • Margins of cavity cross on occlusal contact
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18
Q

process of cavity preparation

A

Identify + remove carious

Remove enamel to identify extent if lesion at the ADJ & smooth the enamel margins

Progressively remove peripheral caries in dentine - from ADJ first, then circumferentially deeper

Only then remove deep caries over pulp

Outline form modification

  • Enamel finishing
  • Occlusion
  • Requirements of the restorative materials

Internal design modification

  • Internal line + point angles
  • Requirements of the restorative material
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19
Q

what should you remove for your final cavosurface margins?

A

remove enamel that will not be supported by the etch technique
- Smooth CSM’s + line angles

Ensure there are no excessively acute line angle transitions and that outline form is smooth + rounded

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20
Q

final cavosurface margins considerations

A

remove enamel that will not be supported by the etch technique
- Smooth CSM’s + line angles

Ensure there are no excessively acute line angle transitions and that outline form is smooth + rounded

Check for stress contractors

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21
Q

what must be checked if removing an existing restoration?

A

no material is left

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22
Q

line angle

A

formed when 2 surfaces of a tooth meet

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23
Q

point angle

A

formed when 3 surfaces meet

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24
Q

cavosurface angle

A

Angle of the tooth structure formed by the junction of a prepared cavity wall and the external surface of the tooth

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25
1st principle of cavity design
access - Apply dam - Remove over lying enamel with high speed fissure bur to gain access to carious dentine (Follow the caries at the ADJ; Do not extend into non-carious areas)
26
2nd principle of cavity design
extent ``` Caries spread at ADJ determines outline form - Encloses extent of caries Clear all caries at ADJ - Check staining at ADJ Smooth enamel CSM’s Examine adjacent contact for caries - Avoid trauma to adjacent tooth ```
27
how to remove an existing restoration
* *NEVER remove a restoration by cutting around the edges - This will over extend the cavity - Start at centre and move towards the edge - Cut into pieces and attempt to ‘chip out’ chunks where possible - Remove any restorative material and any underlying base material
28
3rd principle of cavity design
remove dentinal caries Detected as brown stain or a softened tissue when using a probe - Sound dentine should not yield under probing - Any sticking of the probe indicates residual carious dentine which should be removed Do not probe uncavitated carious enamel Stain should only be left if hard to probe Residual carious dentine must be removed from the ADJ first, then the from the pulpal floor - **caries spreads laterally at the ADJ
29
how should caries at the ADJ be removed?
- Hand-held excavator - Round bur - Chemo-mechanical caries removal - Caries detector dyes may be helpful
30
how should caries at the pulpal floor be removed?
- Large round bur - Large hand held excavator - Chemo-mechanical caries removal using the largest instrument which will conventionally work in the cavity
31
why should small burs/excavators not be used to remove caries on the pulpal floor?
cut deeply and more quickly so more likely to expose the pulp
32
what does enamel caries look like?
white chalky demineralised
33
4th principle of cavity design
modification Once caries/existing restoration is removed - Decide on a restorative material Modify cavity prep as appropriate - Enamel margins - CSMA - Occlusion - Internal anatomy - Dentine quality
34
what are the 2 most commonly used restorative materials for direct plastic restorations?
- composite | - amalgam
35
7 positives of composite
- Aesthetics - Conservation of tooth material - Support for remaining tooth tissue - adhesion / bonding (chemically bonded to tooth) - Command cure (light cure) - Low thermal conductivity - Elimination of galvanism (creation of electrical current caused by two metals coming into contact)
36
negative of composite
technique sensitive
37
positives of amalgam
Strong under occlusal load Prevented from fracture by - Adequate bulk (at least 2 mm deep) Less moisture + technique sensitive
38
negatives of amalgam
Does not bond to enamel or dentine Does not support the tooth Held into the cavity by - Retention - Resistance form Need to remove healthy tissue - For resistance Not tooth coloured Cut dentine required seal resin layer
39
retention
features of the cavity which prevent the restoration from being dislodges in any occlusal direction e.g. undercuts not essential for adhesive restorations
40
retention composite cavity features
Cavosurface angles adjusted to increase bonding area and ensure no unsupported enamel
41
retention amalgam cavity features
Internal dimensions of the cavity greater than access to it
42
resistance amalgam cavity features
Dove tails, keys, flat floors
43
resistance
- Features of the internal cavity design intended to meet the forces of occlusion - Features of the cavity design preventing the restoration to be dislodged in any direction
44
how should the cavity margin/restoration interface be designed?
for maximum strength and minimum leakage
45
how should prisms be aligned for restorations?
bevel to align orientation with prisms for composite consider best approach to achieve end cut prisms
46
cavosurface angle for amalagam
generally 90-120 | butt joint
47
high configuration factor leads to
increased polymerisation contraction stress
48
low configuration factor leads to
reduced polymerisation contraction stress
49
what must be done after finishing cavity preparation?
wash the cavity with a mixture of air and water to remove loose debris, rinse with chlorohexidine and remove - leave surface moist after preparation the cavity will contain: - Loose enamel and dentine chippings - Organic and inorganic dentine debris smeared into walls of cavity
50
what needs to be done prior to placing a dentine bonding agent?
Acid etch applied (35% phosphoric acid). This removes the smear layer and opens smear plugs (i.e. opens tubules) which allows for great wettability by producing a rougher surface area leaving the collagen network exposed for the primer and adhesive to penetrate it.
51
what does acid etch do?
removes the smear layer and opens smear plugs (i.e. opens tubules) - allows for great wettability by producing a rougher surface area leaving the collagen network exposed for the primer and adhesive to penetrate it.
52
how does the dentine bonding agent molecule work?
primers end molecule is hydrophilic and binds to the hydrophilic dentine tubules the hydrophobic methacrylate ends binds to the hydrophobic adhesive
53
what is in Prime and Bond?
HEMA, resin Bis-GMA, acetone & camphorquinone
54
what can be in the adhesive of dentine bonding agents?
filler particles which make it stronger
55
what does dentine bonding agent form when it is light cured
hybrid layer of collagen and resin by micromechanical bonding with the tubules.
56
what material is best used for fissure sealant and why?
bis-GMA | - last longer than GIC fissure seal
57
why do we use fissure sealant?
- To seal fissures and pits to prevent food and bacteria getting caught in them and causing decay. - Because toothbrush bristles cannot clean pits and fissures / expose them to fluoride
58
why would you not use a fissure sealant on a 20 year old?
Patient low risk so unlikely to have caries on molars Preventative measure done only on children
59
what are the main functions of dental dam?
- Protect the airways - Isolation of tooth - Moisture barrier
60
apart from dental dam, what other methods can be used for moisture control?
- Cotton wool rolls - Single tooth dam - Gauze
61
when would you use GIC instead of Bis-GMA as a fissure sealant?
Good moisture control cannot be achieved. High risk children w partially erupted molars Special needs children Poorly cooperating children
62
why and how would you check a fissure sealant is adequately placed?
- Try to dislodge with a sharp probe. - Check there is no air bubbles present. - Check for no interproximal overextension onto soft tissues Do this to ensure the fissure sealant is adequately adhering to the occlusal surface of the tooth
63
affected dentine
- Softened - various levels of demineralised dentine that is not yet invaded by bacteria - inner carious dentine (does not require removal) - Has sensitivity more pulpally - Does not stain acid red with propylene glycol SHOULD BE LEFT TO REMINERALISE
64
infected dentine
- Outer carious dentine - Bacterial plaque - Softened and contaminated w/bacteria - Highly demineralised - Lacks sensation - stains acid red colour with propylene glycol SHOULD BE EXCAVATED
BDS2 CDS Operative Techniques
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