Fix Pros Flashcards
1
Q
A
2
Q
What are the aims of fixed prosthodontics?
A
It ranges from restoration of a single tooth to rehabilitation of the entire occlusion.
The main aims are:
- Restore biological health
- Restore function
- Restore aesthetics
3
Q
What are the two categories of restorations?
A
- Direct - activated in mouth
- Indirect - prepared in labs or milling machines (think outside mouth and cemented in)
4
Q
What are the two types of indirect restorations?
A
- Intra-coronal - inlays or onlays
- Extra-coronal - crowns or veneers
5
Q
Why would you choose a intra-coronal restoration rather than a direct material?
A
- Need for stronger material
- Difficulty with getting appropriate contact with direct restoration
6
Q
What is the difference between the cavity preperation for a direct restoration vs indirect intra-coronal restoration?
A
Cavity prep can not have undercuts
7
Q
What are the functions of a crown?
A
- Reproduces the morphology of the damaged coronal portion
- Restore function
- Protect remaining tooth structure
8
Q
What are the indications for crowns?
A
- Protection of weak tooth structure
- To re-establish the occlusion
- Modification of tooth shape
- Replacement of missing tooth structure
- As retainers
- Aesthetics
9
Q
What are the contraindications for crowns?
A
- Poor oral hygiene and active dental disease
- Cost
- Patient’s age - young patients who have large pulp chambers which may be exposed
- Excessive removal of tooth structure
10
Q
What are some of the considerations for a crown selection
A
- Occlusion
- Endodontic status/vitality
- Other teeth requiring treatment
- Future of tooth
- Future dentition
- Restorability of tooth/teeth
11
Q
What are the parts of a dental bridge?
A
- Abutment - a tooth that serves to support or retain the bridge
- Pontic - an artificial tooth/teeth on a prosthesis that replaces a missing natural tooth
12
Q
What are the indications for a veneer?
A
- Diastema closure
- Alter shape, contour, position
- Alter tooth color
- Mask tooth surface anomalies
13
Q
What are primary functions of a post?
A
- Retain the core
- Stabilise the core
- Obturation of the post canal
14
Q
What are the general checks before commencing fixed pros.
A
- There a control of active disease - periodontal, caries, occlusal
- Ensure the patient can maintain good oral health
- Occlusal analysis
15
Q
WHat are the 5 key principles of crown prep?
A
- Preservation of tooth structure - preserve remaining tooth structure
- Retention and resistance form
- Structural durability - enough thickness of the crown material so it doesn’t fail - each material requires different thickness
- Marginal integrity - utilise finish lnes - bevels, chamfers, shoulders - remember bad margin = caries, gingivitis and perio - to recreate the appropriate finish design - use the right bur! easy peasy (remember to just use half of the bur so you dont create undermined enamel) - burs come in different sizes, so the size of the bur will dictate the width of the finish line
- Preservation of periodontium - dont fuck up the periodontium - put your margins supragingival ideally
16
Q
What is retention and resistance form?
A
- Retention prevents removal of the restoration along the path of insertion
- Resistance prevents dislodgement of the restoration by forces in an apical or oblique direction (rocking)
17
Q
How do we achieve appropriate retention and resistance form in crown prep?
A
- Appropriate taper - the more parallel the walls are - the more resistance you have - combined angle of 6 degrees is optimal (3 degrees deviation at the crownal part comparing to the base of the tooth on each side, 3+3=6)
- MORE SURFACE AREA - think big teeth retain crowns better - more crown height and width
- Path of insertion - NO UNDERCUTS, NO NEIGHBOURING TEETH TILTING
18
Q
How many visits usually does a standard crown prep and insertion take?
A
Usually - 3 visits
19
Q
What happens during the first visit of indirect restoration process?
A
Visit 1: Examination, construction of study models, shade selection, finalisation of treatment plan and consent
20
Q
What happens during the second visit of indirect restoration process?
A
Visit 2: Putty key, confirmation of shade selection, crown prep, secondary impression, provisional restoration
21
Q
What happens during the third visit of indirect restoration process?
A
Visit 3: removal of provisional and insertion of final crown
22
Q
What are your options in terms of temporary crown?
A
- Custom made temporary crowns using protemp4 for example
- Preformed crowns - select appropriate size and Bob is your uncle
23
Q
What are the desirable properties of a cement?
A
- Adhesion to enamel and dentine
- Adhesion to corwn
- Biocompatability
- Adequate compressive strength
- Thin film thickness
- Rapid setting time
- Insoluble in oral fluids
- Transparent colour
- Anticariogenic
24
Q
Why do we use alloys rather than pure metals?
A
Alloys have superior physical and mechanical properties in the oral environment vs pure metals
25
What are some of the desirable clinical properties of dental alloys?
1. Grain size - polishibiltiy
2. Phase structure
3. Yield strength - how is it to bend
4. Hardness - to resist occlusal forces
5. Elastic modulus - stiffness or rigidity of the alloy
6. Colour
7. Corrosion - IT BETTER NOT DO THIS
8. Porcelain-bonding properties
9. Ease of casting
10. Cost
11. Ease of soldering or joining
26
What are the three classifications of dental alloys by composition?
1. High Noble Alloys - noble metal content of above 60% and gold of above 40%
2. Noble Alloy - Noble metal content of below 25% with no gold required
3. Base metal - Noble metal content well below 25% with no gold required
27
What are the properties of high noble alloys?
1. Good biocompatibility
2. Good adhesion between alloy and ceramic
3. Good casting accurate for margins
4. Less creep at high temperature
5. Good physical properties
6. Firing temperature close to ceramica
7. More costly than Noble and base metal alloys
28
What are the properties of base metal alloys?
1. Cheaper than noble alloys
2. Better strength than Noble Alloys
3. More chemically reactive
4. Hypersensitivity potential
5. Higher shrinkage on cooling
6. Thicker oxide layer so adhesion to ceramics may be weaker if not processed correctly
29
What are the requirements for metal-ceramic systems?
1. High melting range of the alloy than the ceramic to resist sintering temperature
2. Low fusing temperature of the ceramic
3. Strong bond to porcelain
4. Adequate stiffness and strength of the alloy to provide good support for the ceramic layer
5. High sag resistance (no change in shape)
6. No discoloration of porcelain
7. Compatible coefficients of thermal expansion of the ceramic and metal - make sure that the materials do not expand or constrict too much
30
What are the 3 systems in high noble metal alloys? And what are their advantages and disadvantages?
1. Gold-Platinum-Paladium - easy to adjust and finish but is VERY EXPENSIVE comperative to others
2. Gold-Paladium-Silver - a bit harder but can change colour
3. Gold-paladium - great properties overall but costs a lot
31
What are the 3 systems in noble metal alloys? And what are their advantages and disadvantages?
1. Palladium-Silver - strong but can be discolorised
2. Palladium-Copper-Gallium - very hard material but has bat adherence to porcelain
3. Palladium-Gallium - idk
32
What are the 3 systems used in base metal alloys?
1. Nickel-Chromium - lower cost but remeber nickel allergy
2. Cobalt-Chromium - good for dentures but the finishing of the material kinda shit
3. Titanium - great biocompatibility but very hard to cast
33
Why do we like to use ceramic?
1. Very stable material
2. Good strength
3. They are thermal and electrical insulators
4. Good biocompatibility
5. Great aesthetic properties
6. Holds shape well
34
What are the contraindications for all-ceramic prostheses?
1. Sever bruxism
2. Extensive wear of tooth structure
3. Excessive bite-force capability
4. A previous history of all-ceramic inlay or crown fractures
35
What is the main aspect we use to classify ceramics?
Composition of the ceramic
36
What are the three main compositions of the dental ceramics?
1. Glass Ceramics - main component is Silica
2. Glass ceramics reinforced with fillers - Silica plus some major filler - example is an Emax crown
3. Polycrystalline ceramics - zirconium oxide matrix
37
What are the three main types of ceramic fabrication?
1. Powder liquid - sintering process of painting material and than putting it into the furnace
2. Slip-Cast All-Ceramic Materials - using refractory molds
3. Heat-Pressed All-Ceramic Materials - heat-pressing
38
What is one of the most important propertie of a ceramic material?
It is the optical propertied of the material - the translucency that is similar to enamel
39
What are the three methods of toughening of a ceramic material?
1. Crystaline reinforcement - the design of crystals is altered
2. Glaze application - glaze applied and when heat up the glaze is able to "tighten" the crown
3. Transformation toughening - certain material can tranfer due to temperature change in the furnace - example zirconia
40
What are the usual thickness of the metal coping thickness in a PBM crown?
1. 0.5mm for noble alloys (lower toughness = thicker metal needs to be applied)
2. 0.3 mm for base metals
41
What is the minimal thickness of the porcelain in the PBM crown?
Minimum is 0.7mm and optimal is 1mm
Meaning that for a full PBM crown with porcelein on all surface - it needs to be minimum 1mm reduction on all surfaces (remember that minimum metal framework thickness if 0.3mm and minimal porcelaine thickness is 0.7mm thus 0.7 + 0.3)
42
What are the four mechanisms of metal ceramic bonding to the tooth?
1. Micromechanical bonsing - use air abrasion to create a clean
2. Compressive forces due to thermal coefficient of expansion - essentially the metal can make the porcelein more compressed due to greater changes in structure from the changes in temperature
3. Molecular bonding - any bonding between molecules
4. Chemical bonding through oxide layer - VERY CRITICAL
43
What are the disadvantages of metal ceramic crowns?
1. Destructive preparation
2. Expensive
3. Increased wear of opposing natural teeth and gold restorations
4. Still not as good looking as natural tooth
5. It can be brittle in areas of porcelain
44
What are some of the other crowns we can use instead of PBM?
1. Porcelain bonded to zirconium
2. Full contour zircona crowns
3. E.max crowns
4. Alumina crowns
5. Full gold crowns
45
What are some of the principles of crown preparation?
1. Conserve and protect hard and soft tissues
2. Maintain retention and resistance form
3. Structural durability - proper thickness
4. Margin integrity
46
What are the measurements for the prep of an anterior tooth
The labial:
1/3 (gingival) - 1.0 to 1.3 mm
2/3 (incisal) - 1.5 mm
Proximal
0.5mm at gingival to 1.5 mm at incisal
Lingual:
Gingival cingulum wall - 0.5mm
Concave surface - if metaland ceramic = 1.0mm, If metal only = 0.5mm to 0.8mm
47
What are the 4 major burs you use in PBM crown prep?
1. Technic 847 - tapered wall and flat end
2. L10 - thin bur
3. Komet 8877 - for shoulder
4. Horico 239 - pear shape bur (VERY AGGRESSIVE)
5. 8877 bur - for smoothness
48
What is the advantage of constructing a temporary crown first before doing a secondary impression?
1. Time may be essential
2. Will show you the undercuts
49
What are the functions of provisional restoration?
1. Pulpal protection
2. Positional stability
3. Restoring function
4. Restoring esthetics
5. Maintain periodontium
6. Protect underlying tooth structure
50
What are some of the options for a temporary crown?
1. Prefibricated - crown formers - could be metal for posteriors!
2. Custom made - using Protemp4
51
What is Protemp4?
It is a composite resin based material that produces no heat, is chemically cured and can create dimension stable crowns.
Caution - please be careful when using on skin might be not a good idea
52
What are the steps of constructing of a temporary crown?
1. Take impression of tooth on study model or intra-orally before cutting preparation - use take one putty
2. Place 'Protemp4' in impression and seat on prepared tooth
3. Remove temp from tooth when resin has set to "rubbery" stage - remove with flat plastic
4. Trim with soflex disc
5. Assess the margins, polish and check contact
6. Check the crown on - cement the crown with temporary cement - preferably eugenol free temporary cement - most common is tempbond
7. Check occlusion but remember that the material might crack
53
What are the criteria for a satisfactory secondary impression?
1. Good recording of crown margins and adjacent cervical tooth/root surface
2. All surfaces and line angls of crown preparation
3. All retentive features
4. Adjacent teeth + 'emergence profile' which is the relationship of cervical tooth contrours and gingival tissues
5. Occlusal surfaces so can articulate upper and lower models
6. Edentulous ridge form for bridgework
54
What do we want to avoid in secondary impressions?
1. Air bubles
2. Absence of voids
3. Abscence of drag lines
4. No contact between teeth and tray
55
How do w achieve a satisfactory secondary impression for our crown prep?
1. Well defined and exposed crown margins
2. Gentle handling and retraction of marginal gingiva - use gingival retraction cord or electrosurgery
3. Remove all surface contaminants
4. Dry working field and moisture control
56
What are some of the things to consider in terms of gingival retraction cords?
1. Size
2. If they are impregnated with a haemostatic agents
57
What technique do we apply when we placing gingival retraction cords?
We use a double cord technique:
1. Primary cord - in order to create vertical displacmenet
2. Secondary cord - usually a one size larger cord - to create vaertical and lateral displacement
58
What are the 3 main types of impression materials?
1. Non-elastomeric materials - not elastic
2. Aqueous Elastomers - water + elastic
3. Non-Aqueous Elastomers - no water + elastic (need dry field)
59
How do polysulfieds set? What is it's advantages and disadvanatages?
They set by condensation reaction between sylfydryl groups with lead dioxide and sulfur. Water and heat accelerate the reaction.
Advantages: good tear strength and low cost
Disadvanatages: Poor dimensional stability and very bad odor
60
How do condensation silicones set? What is it's advntages and disadvantages?
It sets by a condensation reaction
Advantages: very good stability and good tear strength
Disadvantages: Alcohol as by product = bad odor
61
How do PolyVinyl Siloxanes (PVS) set? What is it's advantages and disadvantages?
It sets via cross-linking which is better than condensation. It is the most common material use in light and heavy body.
Advantages: Super stable, odor neutral, great tear strength and elastic recovery - amazing delivry system via a gun (automix) or machine (pentamix)
Disadvantages: chemical reaction reacted with latex, locking into undercuts and open membranes and is expensive as shit
62
How do Polyethers set? What is it's advantages and disadvantages?
It sets via cross-linking and is an excellent material in terms of dimensional stability because it does not have a bi-product int eh reaction
Advantages: amazing ccuracy and very good shelf life
Disadvantages: VERY STIFF VERY VERY STIFF do not use if you have undercuts again VERY STIFF VERY VERY STIFF, shorter working time than PVS silicones and sometimes it gets stuck to oral mucosa
63
What are the trays that we can use for secondary impressions?
1. Stock trays that fit most of people - S, M, L sizes - pretty standard
2. Special position tray - it is custom made, expensive but it is super accurate
3. Triple tray - amazing tray but expensive - dual sided, take bite registration aswell - great for gagging patients
64
What type of adhesive do we use on the tray?
Use PVS for PVS, use PE for PE - dont be an idiot
65
What type of technique in terms of viscosity do we use when constructing a secondary impression?
Dual Viscosity Technique
1. Ask DA to start loading heavy body
2. Remove secondary cord Discard 5 mm of light body on the tray, than inject around the margins of the tooth, entire tooth and adjacent teeth
3. Keep the tie below the surface to avoid air bubbles
4. Seat the tray
5. Allow to set for 5 minutes
6. Remove tray
7. Wash with water
8. Dry impression and assess
9. Send to the lab with instruction
66
What is the post of a post and core system?
1. Preserve remaining tooth structure
2. Protect remaining tooth structure
3. Preserve apical seal
67
What are the three main components of the restoration of endodontical teeth using post and core systems?
1. Dowel (post) - core retention
2. Core - replacement of the lost coronal structure
3. Coronal - restoration itself
68
What is the function of the dowel? What are types of dowels?
Function:
1. Give retention of the core
2. Distribute the stresses along the root
3. Use for obturation
Classification:
1. According to material - metallic, combination and all non-metallic
2. According to attachment - 3 piece (all object separate), detached
3. According to method of construction - pre-fibricated or custom made
69
What are the characteristics of ideal post?
1. Post diameter - diameters should be just sufficient to resist bending but not too large to induce root fracture - wider is better for retention but too wide may result in fracture - recommendation if 1/3 of root diameter
2. Post length -
RULES:
1. two thirds the length of the canal - good retention
2. half the length of the root supported by bone in case periodontally affected tooth
3. A minimum of 4-5 mm of GP should be left '
3. Post material - withstand functional stresses and resists corrosion
4. Radio-opacity - needs to be clearly seen on radiographs
5. Bio-compatible
6. Retrievable
7. Can bond to tooth structure and dental materials
8. Consider crack factor
9. No interference with aesthetics
70
When is post necessary?
A post is required if there is insufficient sound coronal tooth structure remaining to provide stability and retention for the final restoration
71
What are contraindications for posts?
1. If core can be retained and supported without post
2. Non-restorable tooth
3. Short roots, thin roots and carious roots
4. Bends/blockages in root canals
5. Existing tooth pathology
6. Poor periodontal support
72
What are desirable properties for a core?
1. High strength
2. Dimensional stability
3. Ease of manipulation
4. Short setting time
5. Ability to bond to both tooth and dowel
73
What types of cores?
1. Direct - think composite resin cores
2. Indirect - cast metal for examples - mainly if you cant fit a pre-fabricated post
74
What is the "Ferrule Effect"?
Even is you have build up a core - a certain amount of tooth structure needs to remain in order to provide adequate resistance in order to reduce 'splitting' of the root.
75
What are some of the problems with post-retained restorations?
1. Loss of retention
2. Secondary caries
3. Root fracture
4. Post fracture
5. Post bending
6. Root resorption
7. Apical infection
76
Why do we do a PBM crown?
Aesthetics – looks tooth like
Great protection and structural integrity – great for all teeth that are heavily restored or when other methods of restoration have failed
77
What is a structure of a PBM crown?
It is a metal coping veneered with ceramic. Metal coping has thickness of 0.3-0.5mm with 1mm (optimal) layer of a porcelain.
Metal used – higher gold content alloys just because for superior properties but it is expensive
78
What are the preparation dimension for a PBM crow for an anterior tooth
Incisal 2mm
Labial – in 2 palins: Incisal 1.5mm, gingival 1/3 = 1.0-1.3
Proximal = 1.0 to 0.5mm
Lingual = gingival cingulum 0.5mm and concave surface 0.5mm-0.8 mm(for porcelain)
79
What is zirconia?
It is a ceramic metal BUT it is not a metal – rather it is a hexagonal ceramic that does not bend AND it is cheaper.
80
How do we manufacture PBZ crowns?
Using CAD-CAM system (Computer-aided design & computer-assisted manufacturing)
81
Why are PBZ crown bad?
Got it needs a lot of prep. 1.3mm shoulder all around EVEN ON PALATAL. It also needs smooth and rounded surface with no sharp points
82
Why do we have smaller preparation on the lingual part of the posterior teeth?
Due to the fact that the lingual/palatal aspect usually only has the metal and no porcelain
83
What are the occlusal reductions for a PBM?
Metal and ceramic (on both cusps but ONLY DUSIRN PCPC) – 2mm
Metal alone on a non-functional cusp – 1mm
Metal alone on functional cusp – 1.5 mm
84
How do you reduce the buccal aspect on the teeth for a posterior PBM?
Follow the natural tooth anatomy
Some may require 2 planes, some 1. Usually 1.3mm is sufficient
85
What are the difference between zirconia and a gold alloy crowns under severe stress?
Zirconia will crack, gold alloy with bend and stretch
86
Which patient should avoid PBZ crowns?
Very very heavy bruxers
87
What are the dimensions of a PBZ reducction?
1. Occlusal – 2mm
2. Buccal and lingual 1.5 mm
3. Buccal and lingual (gingival) 1mm
4. NO SHARP SURFACES JUST SMOOTH
88
What are the indicitation for gold crowns?
1. Weak surfaces of the tooth
2. When there is insufficient interocclusal distance
3. Heavy bruxism
4. Bridge abutment
5. Reshaping and re-angulating abutment
6. Splinting periodontally mobile teeth
89
How do gold crowns classify?
The lower the gold content – the harder the crown – because gold is soft
90
What are the properties of gold as a dental material?
1. It is thin
2. Ductility unbales burnishing
3. Resists oxidation and is acid stable
91
What are the advantages of full gold crown?
1. Retention and resistance
2. High strength
3. Allows for modification
4. Ease of preparation
5. Bridgework
6. Longevity – excellent
92
What are the disadvatages for a full gold crown?
1. Extensive removal of tooth
2. Not aesthetic
3. Difficult to do a pulp test
4. Iatrogenic damage possible
5. Galvanic current
6. Cost – it is expensive
93
What are the different types of glass ceramics?
They are called feldspathic and they included E.Max Ceram and Duracem KISS
94
What are the different types of reinforced glass ceramics?
There are leucite re-enforced, lithium disilicate and glass infiltrated.
The types of lithium disilicate are E.Max CAD and E.Max press
95
What are the different types of glass free ceramics?
They are Alumina and Zirconia. The subtypes of Ziconium oxide once are E.Max ZirCAD and Nobel Procera Zirconia
96
What is the product range for emax crowns?
IPS E.Max Ceram - Nano-fluorapatite veneering porcelain
IPS E.Max CAD & Press - lithium disilicate (can etch with 5% hydroflouric acid)
IPS E.Max ZirCAD - Zirconium Oxide - good for implants
IPS E.Max ZirPress - Fluorapatite glass-ceramic ingots pressed onto IPS E.Max Zir CAD
97
What are the flexular strength of lithium disilicate?
Around 400 MPa for comperison zirconia is 1120MPa and Alumina 600-700 MPa
98
What are the properties of lithium disilicate?
Crack deflection – resistnceto cracking
High transulency
99
What are the contraindications for an E.Max crown?
1. Very deep subgignival preparations
2. Patient with severley reduced residual dentition
3. Bruxism
4. Long span brudges
5. Posterior bridges
100
What two shade should you select for an E.Max crown?
1. Shade for the crown itself
2. Shade for the cement as it is translucent
101
What are the essential rules for a tooth preparation of a E.Max crown?
1. No angles or sharp edges
2. All margins should be a rounded shoulder or chamfer margin
3. Supragingival margins are essential
102
What pre-treatment should you used before cementation of an E.Max crown?
1. Etch fitting surface with 5% hydrofluoric acid
2. Coat fitting surface with saline agent
3. Cement according to manufacturer's instructions
103
What are the indications of Inlays and Onlays?
1. Aesthetics
2. Present sound tooth structure
3. Sufficient area for bonding
4. When access for direct restoratives a problem
5. Larger cavity restoration
104
What are the advantages of inlays and onlays?
1. Aesthetics
2. Better contact and higher strength compared to direct filling
3. For all ceramic: Good tolerance by gingiva, good durbility and good clinical record
105
What are the important aspects of preparations for inlay?
1. Adequate occlusal depth
2. Cavity divergence
3. Adequate isthmus width
4. No opposing cusp contact
5. Rounded line angles
6. Shoulder finish
7. Remove unsuported enamel
8. Block undercuts
9. No bevels at margins
10. AT LEAST 2mm thickness for ceramic
106
What are the indications for laminated veneers
1. Diastema closure
2. Alter shape, contour, position
3. Alter tooth colour (though limited)
4. Mask tooth surface anomalies
107
What are advantages of laminated veneers
1. Excellent aesthetics
2. Good clinical record
3. Conservative preperations
108
What are the limitations of laminated veneers?
1. Not great at masking dark colours
2. Can not correct severe tooth angulation/position
3. Fragile
4. Post insertion sensitivity
109
What are the important aspects of laminated veneer preparations?
1. Preparation design must keep in enamel
2. Margin placement at gingival crest/subgingivaly
3. Labial reduction 0.5mm cervical, 0.8-1 mm coronal
4. Proximal extensions
110
What are the basic components of post and Core?
1. Dowel (post) - main objective is to retain the core
2. Core – main objective is to replace lost coronal structure
3. Coronal restoration – restore function
111
What are the basic principles of restoring Root-Filled teeth?
1. Preserve remaining tooth structure
2. Protect remaining tooth structure from fractures and bacterial ingress
3. Preserve apical seal
4. Optimise length and width of post
112
What is a dowel?
A dowel is a post usually made of metal that is fitted into a prepared root canal of a natural tooth. It provided retention and resistance to the core. Function: retentin of the core and distribution of the stresses along the root
113
How can we classify posts?
1. By materials – metalic, semi-metalic and non-metalic
2. By attachment – all-in-one system or detached (2 piece or 3 piece)
3. Method of construction – ready-made (direct), cast metal (idirect) and fiber-reinforced composite (direct)
114
What are the different types of pre-fabricated posts?
1. Prallelt, tappered or stepped (element of both)
2. Serrated, smooth or threaded (the most destructive)
115
How do we select an ideal post?
1. Post diameter should be 1/3 of root diameter
2. Post length should be 2/3 of the length of the canal, half of the length needs to be covered by bone and 4mm of gutta percha should be left at the apex
3. Post material shuld be suitable to withstand stress and corrosion
4. Radio-opacity – the post should be radio-opaque
5. Post should be biocompatible
6. Post should be retrievable
7. Post should be able to bond to resin cement
8. Elastic modulus should be similar to dentin
9. It should not interfere with aesthetics
116
What are the contraindication for posts?
1. If core can be retained and supported without post
2. Non-restorable tooth
3. Short roots, thin roots, carious roots
4. Bends and blockages in root canals
5. Existing root pathology
6. Poor periodontal support
7. Endo filled cannals without coronal seal
117
What are some of the direct core materials?
1. Amalgam
2. Composite
3. Glass Ionomer
4. Resin modified Glass ionomer
118
What metals are used in PBM crowns?
Noble metals - with high gold content alloys are preferable. Base metals are cheaper but worst due to worst de-bonding with porcelain
119
How does metal bond to ceramic in a PBM crown?
1. Micromechanical bonding with air abrasion
2. Compressive forces due to thermal cooficient of the metal being slightly higher than porcelaine
3. Molecular bonding - Van der Vaals molecular forces
4. Chemical bonding at high temps - metal oxides dissolve in the softened glass phase
120
What are the different types of margins can be on a PMB?
1. Ceramic radial shoulder
2. Ceramic heavy chamber
3. Heavy chamfer with gold collar
4. 45 degree shoulder with gold collar
121
What can Teknik 847 be used for?
It is a flat tappered bur that can be used to make a flat butt shoulder finish for PBM prep
122
What can Komet 8877 be used for?
It is a torpedo shapped bur that can be used to create a fine chamfer for PBM
123
What can Teknik 856 be used for?
It is a tapered bur with a rounded end that can be used to cut fla shoulder with round internal line angle
124
What is the biggest difference between a PBZ and a PBM crown?
PBZ requires larger reduction and full shoulder unlike a PBM
125
What are the different types of gold are used in fix pros?
Type 1 85% gold - for inlays
Type 3 - 60-70% - for gold crowns
Type 4 - <60% - gold post-and-core and PBM
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What are the reduction dimension for a gold crown?
Occlusal reduction - function cusp 1.5mm, non-functional 1.0mm
Buccal reduction - 1.0mm on buccal to 0.5mm to inproximal
Proximal reduction - 0.5 mm
Lingual reduction - 0.8 occlusal third, 0.5 gingival
Use Komet 8877
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What are the guidelines for preparation of an anterior ZirCAD MT/MT Multi preparation?
Monolithic anterior crowns
0.8 mm all around
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What are the guidelines for preparation of an posterior ZirCAD MT/MT Multi preparation?
Monolithic posterior crowns
1 mm all around
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What are the guidelines for preparation of an anterior ZirCAD LT/MO preparation?
Monolithic anterior crowns
0.4 mm
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What are the guidelines for preparation of a posterior ZirCAD LT/MO preparation?
Monolithic posterior crowns
0.6 mm
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What solution can be used for cleaning prior to cementation of a monolithic zirconia crowns?
Ivoclean universal solution with prior sandblasting
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What cement can be used for cementation of monolithic zirconia crown?
SpeedCEM Plus resin based self adhesive and self curing cement with optional light curing
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What are the three biological requirments for a temporary crown?
1. Biologic - protect tooth structure and periodontal tissue
2. Mechanical - resist functional load, retention, easily removed and used in everyday
3. Aesthetic - natural appearance
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What are the material that can be used for recording pre-op tooth anatomy?
1. Alginate
2. PVS Putty - e.g. honigun and take one
3. Thermoplastic sheets
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What are the materials available for construction of resin custom-made temp crowns?
1. Protemp II bis-acryl composite resin (BIS-GMA)
2. Methyl methacrylate e.g. Duralay - increased shrinkage and pulp toxicity
3. Vinylethyl methacrylate e.g. Trim - powder + liquid
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What are the temporary cements that are available for temp crowns?
1. Tempbond - modified ZnO eugenol cement
2. Eurenol free temp cement suitable for resin bonded ceramics & indirect composite resin restorations - Tempbond NE
3. Poly-F cement - polycarboxylate cement - strong temp cement for long time restoration
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What are the main principles of tooth preparation?
1. Preservation of tooth structure
2. Retention and resistance form
3. Structural durability
4. Clear and sound margins
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What are the properties of idirect resin composites like Sinfony 2M/Espe?
1. Light-cured
2. NOT Bis-GMA/TEGDMA based resin
3. Excelelnt aesthetics
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What are the advantages of indirect resin composites?
1. Superior aesthetics to alloy based restoration
2. Better durability than composite resin
3. Less abrasive than ceramics
4. Easier chairside adjustment
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What are the disadvantages of indirect resin composites?
1. Long temr clinical preformance is meh
2. Loss of surface shine
3. Marginal staining
4. Higher immediate cost
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What are the advantages of dental ceramics?
1. Dimensionally stable
2. Excellent aesthetics
3. Excellent biocompatibility
4. High wear resistance
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What are the disadvantages of dental ceramics?
1. Abrasive
2. Complex fabrication
3. High cost
4. Low fracture resistance
5. Poor stress
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What are some of the preparation of ceramic surface etching?
1. Alluminum oxide filler - 10% HF acided for 1 minutes
2. Leucite - 5% HF acid for 1 minutes
3. Lithium disilicate - 5% HF acide for 20 seconds
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What kind of primer is used for porcelain inlay/onlay crowns?
Silane primer
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What are some of type of fixed bridges?
1. Fixed-fixed bridges
2. Cantilever bridge
3. Spring bridge
4. Fixed-movable bridge
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What is the mechanism of bonding of a rochette bridge?
Rochette bridge binds via macromechanical bonding - resin plugs in alloy retainer and micro-mechanical resin-to-enamel bond
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Why is sand-blasting better than electrolytic etching?
It is;
1. Safer
2. Less technique sensitive
3. Creates good oxide layer for adhesion
4. Less air entrapment
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How can fibre reinforced composites be so srong when individual fibres appear so fragile?
The overall strength of the FRC material is directly related to the volume of fibres, their individual stength and the strength of the resin matrix
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What are some of the materials available for splinting?
1. Resin bonded alloy bridge
2. Resin-bonded FRC frame
3. Pinplay-supported bridge
4. Full crown supported prosthesis
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Where is sanitary pontic? Where is it used?
Used for posterior mandible for easy access for cleaning
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What are some facts about the parallel post?
1. Improved retention
2. Distribute load more passively on the root
3. Less conservative canal preparation
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What are some facts about tapered post?
1. Conform better to shape of canal
2. Inducing the wedhing action of the tooth
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What are some facts about stepped post?
It is the best of both worlds
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What is the prefered surface texture for a post/
The serrated
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What are the two systems that are used in SADS for post and core?
1. ParaPost system
2. RelyX
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What material is LuxaCore?
It is a barium glass in a BisGMA based matrix
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How does sonic fill become more liquidy?
By utilising sonic energu
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What are the 6 types of prosthodontic failure?
1. Traumatic - fracture
2. Biological - caries
3. Mechanical - loss of retentuon
4. Aesthetic
5. Functional - poor occlusal contacts
6. Combinations
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How can we repair damaged porcelain?
1. Isolate, etch with HFA 9% for 2.5m and apple silane primaer
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What does code 545 stand for?
Metalic restoration, 5 surface, gold onlay
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What does code 555 stand for?
Tooth colours restoration, 5 surface, ceramic onlay
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What does 556 code stand for?
Veneer - indirect
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What does 597 code stand for?
Direct post (RelyX, Parapost)
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What does 613 code stand for?
Full crown, indirect, non-metalic
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What does 615 code stand for?
Full crown, indirect, veneered
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What does 618 code stand for?
Full crown, indirect, metalic
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What does 627 code stand for?
Direct core for crown
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What does 643 code stand for?
Bridge pontic - indirect
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What does 649 code stand for?
Retainer for bonded bridge
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