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Operative Dentistry Y2 > Operative > Flashcards

Operative Flashcards

1
Q

What is centric occlusion ?

A

The position of the mandible when the teeth are in maximum intercuspation
Tooth related jaw position

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2
Q

What is centric relation ?

A

The position of the mandible e when the teeth first come into contact in the return dead position
Jaw related position
The heads of the condyls are in their medially braced uppermost untrained position
Ideal F/F occlusion

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3
Q

What is anterior guidance ?

A

The pathway of guidance provided by the palatial surfaces of upper anterior teeth during protrusion of the mandible

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4
Q

What is canine guidance ?

A 
The pathway of guidance provided by the palatal surfaces of the upper canines during lateral movement 
The majority of patients with intact dentition and class 1 occlusion will have canine guidance
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5
Q

What is disclusion ?

A

The separation of posterior teeth during anterior guidance and the separation of anterior teeth during canine guidance

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6
Q

What is group function ?

A

Articulation between posterior teeth on the working side during lateral movement of the mandible
Ideal occlusion for full dentures

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7
Q

Which factors determine occlusion ?

A

Teeth
Left and right tmj
Neuromuscular system

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8
Q

Define caries

A

A process affecting the mineralised tissues ie denting enamel and cementum caused by the action of microorganisms on fermentable carbohydrates

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9
Q

What are the common sites of caries ?

A

Pits and fissures
Approximal
Root surfaces

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10
Q

What are the requisites for caries ?

A

Plaque containing cariogenic bacteria
Substrate eg sugar
Susceptible tooth surface
Time

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11
Q

Which bacteria are involved in the caries process ?

A

Strep mutants
lactobacillus deep lesions
Actinomyces for cervical caries

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12
Q

What is the microscopic appearance of primary enamel caries ?

A

Initiation phase
Destruction of enamel
Invasion of enamel by bacteria
Secondary enamel caries

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13
Q

Describe the initiation phase Of primary enamel Caries

A

Translucent zone
Dark zone
Body of lesion
Surface zone

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14
Q

What is the relative porosity of primary enamel caries ?

A 
Normal enamel is 0.1%
Translucent zone is 1%
Dark zone is 2-4%
Periphery of body is 5%
Centre of body is 25% 
Surface zone is 1%
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15
Q

Describe secondary enamel caries

A

Enamel next to dentine is more susceptible to caries due to branching of tubules

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16
Q

What is secondary / reactionary dentine ?

A

Regular is rapid change of direction of dentinal tubules, similar to primary dentine
Irregular is rapid deposition of dentine due to caries, irregular pattern and little tubules

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17
Q

What risk factors are associated with caries ?

A 
Cultural social and economic status 
Age 
Systemic and topical fluoride 
Sugar intake 
General and dental health knowledge
Medical conditions 
Saliva, plaque and bacterial flora
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18
Q

What are the defence reactions of the pulp dentine complex ?

A

Tubular sclerosis
Secondary dentine
Pulpitis

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19
Q

What are the principles of cavity design ?

A

Gain access
Clear caries from adj
Remove unsupported enamel and grossly carious areas
Extend margins to prevent future disease
Consider retention, occlusal strength
Remove debris and dry

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20
Q

What is GV Blacks cavity classification ?

A

Class I - caries in outs and fissures
Class II - caries on approximal surfaces of posterior teeth
Class III - caries on approximal surfaces of anterior teeth
Class IV - caries on approximal surfaces of anterior teeth including the incisal edge
Class V - carries of the cervical surfaces

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21
Q

Why are crowns placed ?

A

Protect remaining tooth structure
Prevent drifting, over eruption
Restore occlusal function and arch integrity
Aesthetics

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22
Q

What are the indications for a crown ?

A

Cusp fracture

Vertical fracture

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23
Q

What are the contra indications of crowns ?

A

Poor oral hygiene
Insufficient tooth structure
Poor periodontal support
Non vital tooth - untreated periodical disease

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24
Q

What is the diagnostic approach towards crowns ?

A

History
Intra oral examination
Radiographs
Diagnostic models or face bow record

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25
Q

What type of articulation should diagnostic casts be set up on for crowns ?

A

Semi adjustable articulator

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26
Q

What are the advantages of diagnostic casts in The process of crown treatment planning ?

A

Can see edentulous areas
View occlusion from lingual aspect
Assess length of abutment teeth to decide best crown design
Assess abutment teeth drifting, rotation, inclination and buccolingual displacement

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27
Q

What are the biochemical principles of crown preparations ?

A 
Preservation of tooth structure 
Marginal integrity
Retention and resistance 
Preservation of periodontium 
Structural durability
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28
Q

What are the consequences of excessive removal of tooth structure during a crown preparation ?

A

Pulpal inflammation and necrosis

Acceleration of restorative cycle

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29
Q

Define retention

A

The ability of a crown to resist removal along its pathway of insertion

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30
Q

Define resistance

A

The ability of a crown to resist removal from apical, oblique or functional directions

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31
Q

What factors contribute to the degree of retention of a crown ?

A 
Degree of taper 
Length of crown 
Type of cement 
Surface area of cement film 
Amount of cement under shear 
Roughness of the tooth surface
32
Q

What is the ideal degree of taper for a crown ?

A

5-8 degrees up to 16 degrees

33
Q

State the advantages, disadvantages, occlusal reduction and finish line for a full metal crown

A

Adv - little tooth preparation, does not wear opposing teeth
Disadvantage - aesthetics
Occlusal reduction is 1 mm non functional cusp, 1.5 mm functional
Finish line is 1 mm champher

34
Q

State the advantages, disadvantages, occlusal reduction and finish line for an all ceramic crown

A

Adv- aesthetics
Disadvantages- increased wear of opposing teeth, substantial tooth preparation
Occlusal reduction is 1.5-2mm incisally
Finish line is 1.2-1.5 mm shoulder

35
Q

State the advantages, disadvantages, occlusal reduction and finish line for a porcelain bonded to metal crown

A

Adv- aesthetics, reasonable tooth prep
Disadvantage - wear of opposing teeth
Occlusal reduction is 2 mm
Finish line is 1.2 mm shoulder on labial surface and 0.5 mm champher on lingual surface

36
Q

What is the history of the rubber dam ?

A

First introduced in 1864 by Dr Sanford Barnum
Clamps in 1870
Harness on 1881
Frame in 1900

37
Q

What are the advantages of rubber dam ?

A

Safety
Moisture control
Patient control

38
Q

What is the role of the rubber dam in protecting soft tissues ?

A

Liquid etchant can penetrate cotton wool roll leading to gingival ulceration

39
Q

What are the disadvantages of the rubber dam ?

A

Damage to gingivae
Feature of tooth or restorations
Allergy
Inhalation or swallowing of clamps

40
Q

What are the dimensions of the rubber dam ?

A

15x15 cm , 0.15-0.35 mm thick, 3 year shelf life

41
Q

What is the difference between a bland and retentive clamp ?

A

Bland clamps above the gingival margin, retentive clamps below

42
Q

What is the disadvantage of using a green or blue rubber dam ?

A

Poor for shade selection

43
Q

Where should the rubber dam stamp be placed ?

A

1.5 cm below the top of the dam

44
Q

Which sized holes are suitable for which teeth when preparing a rubber dam ?

A 
A for mandible are molars and large maxillary molars 
B for maxillary molars and small molars 
C for canines and pre molars 
D for maxillary incisors 
E for mandibular incisors
45
Q

What are the relative merits of placing the clamp after the rubber dam ?

A

Only technique possible for double winged clamps

Restricted to anterior and premolars teeth

46
Q

What are the relative merits of placing the rubber dam and the clamp together

A

Ideal for third molar teeth and endodontics

47
Q

What are the relative merits of placing the rubber dam after the clamp ?

A

Ideal for posterior teeth but not third molars

Minimises the risk of gingival trauma

48
Q

What proportion of lesions are due to fissure caries ?

A

84%

49
Q

What are the non invasive diagnostic methods for fissure caries ?

A

Visual, tactile, electrical, magnification, radiographs , trans illumination, caries detection dyes

50
Q

Why is tactile probing not a suitable method for the diagnosis of fissure caries ?

A

Can introduce cariogenic bacteria into fragile surface zone

51
Q

What type of fissure lesion can be seen in a radiograph ?

A

Occult caries

52
Q

How can dyes diagnose caries ?

A

Selectively complex with carious tooth structure which can be detected by fluorescence
Allows quantitative and qualitative assessment of caries

53
Q

Which dyes are used to detect enamel caries ?

A

Procion- n2 and oh groups irreversibly bond to caries
Calcein- complexes with calcium
Zyglo- not used in vivo
Brilliant blue - not used in vivo

54
Q

Which dyes are used to detect dentine caries ?

A

1% acid red 52 in propylene glycol complexes with dentures dentine
Iodine penetration method measures enamel permeability

55
Q

What are the disadvantages of caries detection dyes ?

A

Dye staying and bacterial penetration are independent events
Dye stains food, pellicle, adj
Dye aided caries removal is laborious

56
Q

How does diode laser fluorescence detect caries ?

A

680 mm wavelength
Optical tip has one transmission fibre and 8 fibres to detect reflected light
Caries has a different fluorescence than normal tooth structure
80% sensitivity

57
Q

How do light emitting diode based devices eg vista proof detect caries ?

A

Violet light 405 nm
Porphyrins metabolites from bacteria are red
Normal tooth structure is green

58
Q

How do electrical methods diagnose the presence of caries ?

A

Demineralisation increases tooth porosity
Porosity contains fluid with increased ions
Increases electrical conductivity
Very high sensitivity and can be used to monitor the progression of a lesion

59
Q

What treatment options are available for fissure caries ?

A 
Observation 
Laser therapy 
Ozone treatment 
Sealant restoration 
Normal restoration
60
Q

How does laser therapy treat caries ?

A

Experimental co2 laser
Re organisation of HA structure
Probably will not raise pulp above 1 degree but no clinical trials

61
Q

Which materials can be used as sealant restorations ?

A

Gic, composite, compomer, fissure sealant , dentine adhesive

62
Q

What are the advantages of the sealant restoration technique in the treatment of fissure caries ?

A

Little tooth prep
Does not weaken tooth structure
Aesthetic
Preventive

63
Q

What is a cavity ?

A

A permanent defect in tooth structure which leads to destruction

64
Q

What is a tooth preparation ?

A

Iatrogenic alteration of the tooth structure in order to accommodate filling material to restore the tooth integrity

65
Q

What is a conventional tooth preparation ?

A

Follows a specific depth, patter, marginal adaptation and form
For amalgam, metal and porcelain materials

66
Q

What is a modified preparation ?

A

Used when bonding of the filling material to tooth structure is possible eg composite, compomer gic

67
Q

What is the classification of radiographic depth scale ?

A

E1 is caries confined in the outer 1/2 of enamel
E2 is caries conforms to the inner 1/2 of enamel
D1 is caries 0.5 mm into dentine
D2 is caries more than 0.5 mm into dentine but less than 0.5 mm from pulp
D3 is caries within 0.5 mm of pulp

68
Q

How long does caries take to reach the adj in deciduous teeth ?

A

3-4 years

69
Q

How long does caries take to reach the adj in permanent teeth ?

A

6 years

70
Q

Which type of cavity most commonly causes cusp fracture in posterior teeth ?

A

Mod

71
Q

What are bonded amalgam restorations ?

A

A resin or gic based luting cement is placed into the cavity followed by the amalgam before the cement sets
Reduces marginal leakage
Useful for non retentive cavities
Increases cost

72
Q

What are the indications for posterior composite restorations?

A

Small or medium class II cavities
Allergy to metals
Non retentive cavity
Where unsupported enamel may be strengthened by composite

73
Q

What are the contraindications of posterior composite restorations ?

A 
Poor oral hygiene 
Susceptibility to caries 
Poor moisture control
Multiple large cavities with contact involvement 
Allergy 
Bruxing and grinding habits
74
Q

What problems are associated with large class II composite restorations ?

A

Micro leakage and secondary caries
Wear and fracture
Cuspal flexure and post op pain

75
Q

How long on average do amalgam restorations last ?

A

15 years

76
Q

How long on average do composite restorations last ?

A

6 years

Operative Dentistry Y2 (7 decks)

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