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Dentistry-5th semester > Fixed Prosthodontics II > Flashcards

Fixed Prosthodontics II Flashcards

1
Q

which are the advantages of inlays/onlays?

A
  • Using a prefabricated materials results in superior physical properties, possibly providing a lifespan of 2 to 3 times longer than the clinically finished fillings.
  • Generally more accurate representation of tooth’s original morphology compared to placing normal restoration.
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2
Q

which are the disadvantages of inlays/onlays?

A

More invasive technique because requires preparation of a “path of insertion”.

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3
Q

which are the advantages of Veneers?

A
  • Minimally invasive / non-invasive method.
  • Allows certain corrections of the size, shape and the colour of the teeth.
  • Can be considered as an alternative of orthodontic treatment.
  • Highly aesthetic option.
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4
Q

which are the disadvantages of Veneers?

A
  • Can be used only in healthy teeth that have not been previously restored or have minimal restorations on the approximal and lingual/palatal side.
  • Can be invasive.
  • Can fracture. Have to be and mainly rely on bonding.
  • Due to the translucency may not fully cover some discolorations.
  • Cost?
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5
Q

which are the advantages of Fixed Partial Dentures (FPD) / Conventional Bridge?

A

▪ Fast and effective method for substitution of missing teeth.

▪ Can be used in areas with serious bone loss on the edentulous part.

▪Allows corrections of the size and the colour of the teeth.

▪ Highly aesthetic.

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6
Q

which are the disadvantages of Fixed Partial Dentures (FPD) / Conventional Bridge?

A
  • Can be used only in teeth with comparatively healthy periodontium.
  • Requires preparation of healthy teeth up to 45% of their volume.
  • Similarly to crown preparations there is a risk of devitalisation
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7
Q

which are the advantages of Posts?

A
  • Allows restoration of severely damaged teeth and provides support for the crown.
  • Can be used for certain corrections of improperly inclined teeth.
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8
Q

which are the disadvantages of Posts?

A
  • Can be used only in endodontically treated teeth.
  • Increase the risk of root fractures.
  • High risk of root perforation or root resorption.
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9
Q

which are the advantages of Dental Implants?

A
  • An alternative method for substitution of missing teeth.
  • Considered now as better solution when abutment teeth are sound teeth.
  • No need for preparation of the adjacent dentition.
  • Can be used as an attachment for almost all types of restorations.
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10
Q

which are the disadvantages of Dental Implants?

A
  • Can’t be used if we have insufficient amount of bone (considering no bone augmentation is carried out).
  • The treatment time is longer than the treatment with FPD or RPD.
  • The remaining dentition should not be affected by any chronic disease (periodontal).
  • Requires meticulous hygiene of the patient and strict visits for regular check-up.
  • Invasive procedure – Surgery involved.
  • Contraindicated in certain Medically involved patients.
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11
Q

Which is the role of Splints?

A

➢ To test increase in occlusal vertical dimension.

➢ To check patient is in RCP (Retruded position).

➢ To treat Temporomandibular disorder (TMD) patients where the pain is of muscle origin.

➢ To prevent toothwear before and after restorative care.

➢ To check patients can wear partial dentures or overdentures or onlay dentures

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12
Q

What are crowns indicated for?

A
  • Protection of the remaining tooth structure (teeth can be sufficiently weakened through extensive caries, large restorations, extensive wear, endodontic treatment, presence of cracks)
  • Alteration of Aesthetics
  • Alteration of crown form to facilitate the construction of removable partial dentures (act as abutments)
  • To alter the occlusal plane
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13
Q

Which material is used for All Ceramic Crown?

A

E-max

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14
Q

which are the advantages of All Ceramic Crown?

A
  • Excellent Aesthetics
  • Preservation of tooth structure in some areas
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15
Q

which are the disadvantages of All Ceramic Crown?

A
  • Increased destruction of tooth structure in some areas
  • Longevity
  • Moderate strength
  • Abrasive to opposing teeth
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16
Q

which are the advantages of Ceramo-metal Crown?

A
  • Good Aesthetics
  • Longevity
  • Preservation of tooth structure in some areas
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17
Q

which are the disadvantages of Ceramo-metal Crown?

A

Increase destruction of tooth structure in some areas

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18
Q

Which are the advantages of Full Gold Crown?

A
  • Control and stability of occlusion (kind to opposing teeth)
  • Longevity
  • Maximal preservation of tooth structure
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19
Q

Which are the disadvantages of Full Gold Crown?

A
  • Poor aesthetics
  • Can be expensive these days
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20
Q

Which are the advantages of Partial coverage?

A
  • Good aesthetics
  • Longevity
  • Preservation of tooth structure
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21
Q

Which are the disadvantages of Partial coverage?

A
  • Complicated to prepare and to manufacture
  • Moderate aesthetics – depending on material and colour match
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22
Q

Which are the advantages of Monolithic Zirconia Crown?

A
  • Very good aesthetics
  • Control and stability of occlusion (fairly kind to opposing teeth)
  • Durable (high fracture resistance)
  • Near maximal preservation of tooth structure
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23
Q

Which are the disadvantages of Monolithic Zirconia Crown?

A
  • No true bonding (issue with longevity)
  • Can be layered with porcelain but this leads to increased destruction of tooth structure
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24
Q

Biologic width:

A
  • Junctional epithelium= 0.97mm
  • Connective tissue attachment= 1.07mm
  • Biologic width= 0.97mm + 1.07mm = 2.04mm
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25
Q

Which are the advantages of Full Coverage metal crowns?

A
  • Best control of occlusion
  • Best retention and resistance form from all indirect restorations
  • Least destructive as more tooth structure is preserved when preparing the tooth
  • Usually best marginal fit
  • Kindest to opposing teeth
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26
Q

Which are the disadvantages of Full Coverage metal crowns?

A
  • Poor aesthetics
  • If NON-precious metal used irregularly, they may cause allergy or they may corrode
  • Can be too soft in some situations
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27
Q

Which are the indications of Partial crowns 7/8?

A
  • The primary indication for a 7/8 crown is to restore a maxillary first molar where the mesiobuccal enamel surface is intact.
  • This eliminates the need for porcelain (or some other ceramic material), which is not as durable as gold, and it also has the esthetic advantage of maintaining natural tooth structure.
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28
Q

Which are the contraindications of Partial crowns 7/8?

A

The primary contraindication for a 7/8 crown is when there is some defect or esthetically compromised quality in the buccal enamel of the mesiobuccal cusp.

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29
Q

which is the use of UNC-15?

A

Used to measure the periodontal pockets and make us aware of the biologic width prior to any crown preparation.

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30
Q

which is the use of UNC-15 + Williams Probe?

A

Can be used together with the putty indices to measure the reductions.

  • For a shoulder margin only the UNC 15 and Williams can be used.
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31
Q

which is the use of UNC – 15 Probe / Williams Probe/ BPE Probe?

A
  • All three instruments can be used to check if a chamfer margin is correct – even the BPE probe as the ball tip is 0.5mm.
  • They can all be used to remove any excess cement during the cementation stage.
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32
Q

which is the use of Straight Probe?

A
  • Used mainly to access the margins of the crown – both definitive and provisional
  • Can be used with care to remove excess cement
  • Should not be used to measure any pocket depths as can be traumatic.
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33
Q

which is the use of Flat Plastic?

A
  • Used to remove the provisional crown.
  • Can also be used when modifying the provisional crown with flowable composite – used for shaping.
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34
Q

Retraction cords:

A

They exist in different sizes ranging from size 000 (finest) to size 3 (largest). They are placed within the gingival crevice prior to taking any master impression for fabrication of indirect cast restorations.

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35
Q

Retraction cord packer:

A

is a designated instrument to aid insertion of the cord within the crevice.

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36
Q

Haemostatic agents:

A

such as Racestyptine are used to soak the retraction cord prior to insertion in the crevice.

  • This liquid is impregnated with aluminium chloride that gives a gentle astringent effect and has excellent haemostatic properties.
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37
Q

Articulating papers-use:

A
  • To check occlusal contacts.
  • In crowns they are used to check if the provisional and definitive crowns are harmonious with the remaining occlusal contacts.
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38
Q

Normal Articulating paper:

A
  • can be 70-200 microns
  • Thick and mainly used for dentures
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39
Q

GHM articulating paper:

A
  • 12-20 microns
  • Ideal to check occlusal contacts – most frequently used in restorative dentistry
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40
Q

Shimstock:

A
  • 8 microns
  • also used in crowns** and **implant crowns.
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41
Q

Traditional porcelain composition:

A
  • Traditional porcelain is a blend of three main materials: kaolin**, **quartz** and **feldspar, and firing at high temperature.
  • There are also small concentrations of Alumina, oxides of sodium, potassium and calcium and metal pigments.
  • Ceramic is a term used to describe any product that is essentially made from a non- metallic inorganic material** usually processed by **firing at a high temperature to achieve desirable properties.
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42
Q

Dental all ceramic materials-3 groups:

A
  • Glassy ceramics
  • Particle filled glass ceramics
  • Polycrystalline ceramics
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43
Q

Crystalline ceramic:

A

Higher strength ceramic substructures

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44
Q

Glass ceramic:

A

Highly aesthetic substructures

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45
Q

Feldspar:

A
  • Basic Glass former (60-80%)
  • Natural occurring mineral
  • Has most of the components that are needed to make dental porcelain
  • When heated at high temperature it forms feldspathic glass
  • Quite transparent
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46
Q

Kaolin:

A
  • Acts as a binder (3-5%)
  • White clay like material
  • Give the opacity to the mass
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47
Q

Quartz (Filler):

A
  • Filler (15 to 25%)
  • Provides strength and hardness to porcelain during firing
  • Form of silica
  • Ground quartz acts as a refractory skeleton
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48
Q

All Ceramic Crowns-Advantages:

A
  • Most Aesthetic option as ceramic restorations transmit light through them giving a life like appearance
  • Metal free restorations
  • Biologically acceptable and well tolerated by soft tissues
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49
Q

All Ceramic Crowns-Disadvantages:

A
  • Tooth preparation more destructive
  • Long Term survival not as promising as ceramo-metal crowns. However, improved with recement ceramics
  • More demand on clinicians knowledge for choosing the appropriate system
  • Wear on opposing dentition
  • Low repair potential
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50
Q

Glass-matrix Ceramics:

A
  • Non-metallic inorganic ceramic materials that contain a glass phase
  • Feldspathic+synthetic+Glass-Infiltrated alumina
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51
Q

Feldspathic:

A

suitable for veneering metal substructures

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52
Q

synthetic:

A
  • suitable for inlays, onlays, crowns, 3-unit fixed prosthesis in anterior region
  • e-max
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53
Q

Polycrystalline Ceramics:

A
  • Non-metallic inorganic ceramic materials that do not contain any glass phase.
  • Absence of a glass phase
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54
Q

Absence of a glass phase in Polycrystalline Ceramics:

A

makes the polycrystalline ceramics difficult to etch with hydrofluoric acid, requiring long etching times or higher temperature.

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55
Q

Polycrystalline Ceramics-alumina:

A
  • First introduced in mid- 1990s as a core material for fabrication with CAD/CAM.
  • It had very high hardness and relatively high strength and high elastic modulus.
  • However, it led to vulnerability to bulk fractures.
  • This led to the introduction of materials with improved mechanical properties, such as transformation toughening that is found in stabilized zirconia.
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56
Q

Polycrystalline Ceramics-Stabilized zirconia:

A

Can undergo transformation toughening (changes from monoclinic to tetragonal) and leads to 4% volume increase that can close any cracks, leading to large increases in fracture toughness of the material. In order to get good aesthetics this material needs staining.

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57
Q

Polycrystalline Ceramics: Zirconia- toughened alumina & alumina- toughened zirconia:

A

Composites with zirconia or alumina to improve their strength, fracture toughness, elasticity, hardness and wear resistance.

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58
Q

Ceramo-metal crowns vs. All Ceramic Crowns:

A
  • Ceramo-metal: Chamfer margin (0.5mm) and shoulder (1.2mm) only buccally where the porcelain is added.
  • All ceramic crown: Deep chamfer / shoulder margin (minimum 1mm) circumferentially
  • All ceramic crowns require more tooth destruction compared to ceramo- metal crowns
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59
Q

Contraindications for All Ceramic Restorations:

A
  • Teeth with large pulp space, such as your teeth
  • Adequate tooth reduction is likely to cause pulpal exposure
  • Bruxist
  • Porcelains may be sheered off under excessive occlusal forces.
  • Can be abrasive on opposing teeth
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60
Q

Monolithic Zirconia Crowns:

Advantages:

A
  • Zirconia crowns are highly biocompatible, as the smooth surface helps to reduce plaque accumulation
  • Zirconia is suitable for patients with metal allergies** or who would prefer to have **metal- free restorations.
  • The fairly translucent nature of this material can t_ransmit some of the colour of adjacent teeth_ and it is manufactured in a wide variety of shades, making it easy to accurately match the colour of the patient’s natural teeth.
  • Increased strength and durability making them hard to chip or fracture.
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61
Q

Monolithic Zirconia Crowns:

Disadvantages:

A
  • Expensive: zirconia crowns may cost you more than other crowns.
  • May wear out the opposing teeth: as zirconia crowns are too tough, they may prove stronger against your natural teeth.
  • Although can be fairly translucent they are still not as translucent as all ceramic crowns.
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62
Q

Active and passive in relation to the mucosa:

Impression:

A
  • passive**: gypsum, zinc oxide eugenol, **low viscosity alginate materials which are more fluid and displace tissues less
  • Active**: high viscosity alginates, **high viscosity elastomers
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63
Q

Elastic impression materials:

A
  • Hydrocolloid – reversible and irreversible
  • Polysulfide
  • Silicones –condensation and addition
  • Polyether
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64
Q

Hydrocolloids:

A

have the advantage of WETTING INTRAORAL SURFACES well, but have very limited dimensional stability because they are composed of 85% water.

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65
Q

Agar-Definition:

A

Agar is chemically an organic, hydrophilic hydrocolloid extracted from certain seaweeds, sulfuric ester of a linear polymer of galactose a gel, but on heating becomes a sol.

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66
Q

Agar-use:

A

used extensively for crown and bridge impression before elastomers came to the market. Widely used at present for cast duplication.

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67
Q

Agar-Supplied as:

A

Gel in collapsible tube for impression

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68
Q

Alginate:

A
  • Definition: Irreversible hydrocolloid
  • A mucous extract yielded from certain brown sea weeds.

Types:

Type I: fast setting

Type II: Normal setting Application:

  • For impression
  • In mouth with excessive flow of saliva
  • For impression to make study models and working casts
  • For making preliminary impression
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69
Q

Plain retraction cord:

Aim:

Disadvantage:

A
  • Aim: Sulcus enlargement (physically displace the gingivae away from the finish line.
  • Disadvantage: Sulcular haemorrhage->leading to difficulty in maintaining moisture control and poor accuracy of impression (impression materials are hydrophobic)
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70
Q

Copper band:

Aim:

A
  • Aim: To displace the gingivae and helps to carry the impression material to ensure the finish line is captured in the impression.
  • Disadvantage: Traumatic, Not effective, Not accurate
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71
Q

Impregnated retraction cord:

Disadvantage:

Staining Solutions:

Methods:

A
  • This is retraction cord soaked in a chemical solution.
  • Chemomechanical process combining gentle packing of retraction cord to enlarge the sulcus with chemical action to control sulcular haemorrhage creating a more accurate impression of the preparation margins.

Disadvantage:

  • Systemic side effects
  • Inflammation and tissue necrosis

Staining Solutions:

  • Ferric Sulphate 15%
  • Alum ALK(SO4)3
  • Aluminium Sulphate

Methods:

  • Method 1 – Removal of the cord)
  • Method 2 – Leaving the cord in the sulcus)
  • Dual cord technique
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72
Q

What are RBBs?

A

Resin Bonded Bridges / Resin Retained Bridges (RBBs/RRBs) are a minimally invasive bridge option which rely on composite resin cements for retention.

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73
Q

RBBs-Components:

A
  • Wing
  • Connector
  • Pontic
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74
Q

RBBs-Pontic:

A
  • The pontic is usually porcelain fused to metal substructure. The part that replaces the missing tooth.
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75
Q

RBBs -Connector:

A

The part that links the pontic with the wing.

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76
Q

RBBs -Wing:

A

The wing or retainer is usually fabricated from non precious metal alloy in thin section and is treated to enhance the micromechanical adhesion between the prosthesis and the composite resin cement.

  • The metal used is either Nickel chromium alloy** or **cobalt-chrome alloy sandblasted with 50 microns alumina
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77
Q

RBBs -Advantages:

A
  • Minimally invasive – relatively reversible
  • Requires less clinical time
  • Less expensive
  • Less demanding to fit (although moisture control imperative)
  • Failure less catastrophic than with conventional bridges or implant retained prostheses.
  • Aesthetic
  • Predictable restoration
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78
Q

RBBs -Disadvantages:

A
  • The aesthetics are determined by the tooth the retainer wing is attached to and in the anterior regions the quality and thickness of enamel, the porcelain on the pontic, the extend of the soft tissue defect in the pontic regions and how the soft tissues are managed.
  • Metal connectors may shine through translucent incisors causing them to appear grey.
  • Can de-bond as they only relying on the chemical bond between the tooth cement and metal interface.
  • Recementing is less successful** and **predictable that the initial cementation.
  • Longevity** and **success rate are inferior to the ones provided by implants.
79
Q

Design principles required for RBB:

A
  • Design should be kept as simple as possible
  • Should cover as much of the abutment tooth as possible but minimal thickness of retainer (0.7mm)
  • Be rigid – connector and retainer
  • Hygienic pontic design
  • Permit the control of the occlusal contacts (no contact on pontic in excursions)
80
Q

RBB -Cantilever Design:

A
  • Involves the use of single retainer
  • Abutment tooth maybe either mesial or distal (mesial cantilevers have better longevity)
  • Less expensive, but limited to replacing one missing tooth
  • Better longevity
  • Less likely to fail due to caries
81
Q

RBB -Fixed-Fixed (Maryland) Design:

A
  • One or more retainers are placed on either side of the pontic
  • Problem with debonding due to differential movements of abutment teeth
  • This design of bridge is indicated where excursive movement on pontics cannot be avoided.
82
Q

RBB -Fixed-movable design:

A

Has a rigid connector usually at one end and a movable connector that allows some vertical movement at the other end.

83
Q

RBB -Hybrid design:

A

A combination of a conventional retainer at one end and a resin- bonded retainer at the other end of the pontic.

84
Q

Types of materials used for RBBs:

A
  • Metal framed
  • Fibre-reinforced composite
  • Ceramic / Zirconia
85
Q

Metal framed RBBs:

A
  • Conventionally made substructure that is a non-perforated** and **sandblasted non-precious metal that is cemented with a chemically active resin cement.
  • A disadvantage to this type of bridge is the appearance of the abutment tooth which can appear grey due to the decreased translucency.
  • The metal substructure can be visible and may not be suitable for highly aesthetic cases.
86
Q

Fibre-reinforced composite RBBs:

A
  • Have improved aesthetics and adhesion** of luting agent to the framework as well as **lower costs.
  • An additional advantage is that they can be usually fabricated in mouth during a single visit** or i_ndirectly in the laboratory._**
  • Their main disadvantage is that fracturing and wear of the composite can be commonly seen.
87
Q

Ceramic / Zirconia RBBs:

A

Previously glass-infiltrated aluminium oxide ceramic frameworks were used. More recently, yttrium tetragonal zirconia polycrystal based materials have come into use.

  • The main advantage of this type of bridge is aesthetics** as well as **good biocompatibility** and **lower levels of plaque accumulation.
  • However, connector dimensions are greater than those needed for other types of RBBs and they tend to debond more easily.
88
Q

Fixed Partial Denture (Conventional Bridges):

A

Prosthetic treatment permanently or temporarily attached to remaining teeth, or implants which replaces one or more missing teeth. This type of restoration is what know as a “Bridge”.

89
Q

Articulator-Types:

A
  • Simple hinge articulators.
  • Fixed or mean value condylar path articulators.
  • Adjustable condylar path articulators.
  • Semi-adjustable condylar path articulators.
  • Fully adjustable condylar path articulators
90
Q

Non-adjustable condylar path articulators:

Possible movements:

A
  • simple hinge articulators (class I)
  • The hinge articulator is NOT an articulator! At best it is a cast holder. The only movement is an inaccurate opening and closing.
  • Possible movements: Opening and closing movements only
91
Q

Mean value or Fixed condylar path articulators (Class II):

A

Possible movements:

  • opening and closing
  • protrusive movement at a fixed condylar path angle.

Disadvantages:

  • Most of these articulators do not accept face-bow record
  • The condylar path moves to a fixed angle and it is successful in patients whose condylar angle approximates that of the articulator.
  • No lateral movements.
92
Q

Semi Adjustable Condylar Path Articulators:

Possible movements:

A
  • •Opening and closing.
  • Protrusive movement to an angle recorded from the patient.
  • Lateral movement to an angle
93
Q

Fully vs Semi- adjustable articulators:

A
  • They differ from the semi- adjustable articulators in that the lateral condylar path inclinations are adjusted according to records taken from the patient.
  • These types of articulators differ from fixed condylar path articulators in that have _adjustable condylar and incisal guidance._They can be adjusted so that the movements of its jaw members closely resemble all movements of the mandible for each individual patient
94
Q

Arcon Articulator:

A
  • non-arcon: condyles attached to the upper member of the instrument
  • arcon: condyle attached to the lower member as occurs in nature
95
Q

Rotating condyle:

A

In a lateral mandibular movement the condyle on the side toward which the mandible moves is termed the rotating condyle

96
Q

Orbiting condyle:

A

The condyleon the side opposite the side towards which the mandible moves is termed the orbiting condyle.

97
Q

Posselt’s Diagram:

A
  • Showing Sagittal Jaw Positions
98
Q

Centric Relation (CR):

A

A bilateral, unstrained position of the mandible in which the condylar disc assembly is in the most superior anterior position in the glenoid fossa and the initial 20 mm of incisal opening is a pure hinge axis.

99
Q

Maximum Intercuspal Position (ICP):

A

This is the position where there is most tooth-to-tooth contact for that individual’s occlusion.

100
Q

RCP:

A

Which position do we record and when?

  • RCP is the only reproducible position of the occlusion so is used when we want to make large changes to the occlusion (eg. restoring multiple units) in the fully dentate individual.
101
Q

jaw relationship:

Re-organised approach:

A
  • RCP is the only reproducible position of the occlusion so is used when we want to make large changes to the occlusion(eg. restoring multiple units) in the fully dentate individual.
  • To alter the occlusion** in this way is called Re-organised approach and is used in **wear cases** or **when restoring multiple units.
  • RCP is also used when dealing with edentulous patients (making complete dentures)
  • Re-organised approach is used in more complex treatments.
102
Q

jaw relationship:

Conformative approach.

A
  • We can also use ICP the intercuspal position, when we conform to the patients’ occlusion.
  • This is what you are doing every time you place a restoration, you ensure that the restoration harmonises with the occlusal scheme.
  • For the majority of your clinical work as a General Dental Practitioner you will use the conformative approach.
103
Q

jaw relationship

Manipulation of Mandible into CR:

A
  • Chin point guidance (helps if you have the patient reclined and ask him/her to roll his/her tongue to touch the palate and gently close their mouth)
  • Chin point guidance with anterior jig
  • Bimanual Manipulation
  • Using a splint
104
Q

Zinc Phosphate Cement:

Indications:

A

(longest used cement, however less commonly used nowadays)

  • Single metal or metal-ceramic crowns, Lithium Disilicate, Zirconia crowns with retentive design features.
  • Fixed-partial metal-ceramic dentures
  • Posts – material of choice due to post set expansion.
  • Multiple cementations
105
Q

Zinc Phosphate Cement:

Advantages:

A
  • Longest track record
  • High compressive strength
  • Low film thickness
  • Reasonable working time
  • Resistant to water dissolution
106
Q

Zinc Phosphate Cement:

Disadvantages:

A
  • Low tensile strength (preparation geometry very important)
  • No molecular adhesion to tooth or crown material
  • Not resistant to acid dissolution
  • Powder/Liquid ratio and mixing technique very important for its material properties
107
Q

Polycarboxylate Cement:

Indications:

A
  • As for zinc phosphate cement
  • Traditionally used for vital or sensitive teeth (but no evidence to support its efficacy)
108
Q

Glass Ionomer Cement:

Indications:

A
  • Single metal or metal-ceramic crowns
  • Fixed-partial metal-ceramic dentures
  • Patients with high risk caries (Fluoride release)
109
Q

Glass Ionomer Cement:

Advantages:

A
  • High compressive strength
  • Low film thickness
  • Reasonable working time
  • Fluoride release
  • Forms considerable bond to tooth
  • After setting, resistant to water dissolution
  • High compressive strength
110
Q

Glass Ionomer Cement:

Disadvantages:

A
  • Sensitive to early moisture contamination (protection of margins)
  • Low tensile strength
  • No molecular adhesion crown material
  • Not resistant to acid dissolution
111
Q

Resin-modified Glass Ionomer Cement:

Indications:

A
  • Single metal or metal-ceramic crowns and partial fixed dentures when preparation geometry is borderline
  • Currently NOT recommended for ceramic crowns, onlays or veneers
112
Q

Resin-modified Glass Ionomer Cement:

Advantages:

A
  • High compressive and tensile strength
  • Reasonable working time
  • Low film thickness
  • Fluoride release
  • Molecular adhesion to tooth
  • Resistant to water dissolution
113
Q

Resin-modified Glass Ionomer Cement:

Disadvantages:

A
  • Short track record
  • Water absorption causes expansion and cracking of overlying ceramic
114
Q

Resin Cement:

Indications:

A
  • Porcelain veneers
  • Ceramic, Zirconia and composite onlays
  • Ceramic, Zirconia crowns or fixed-partial dentures
  • Resin-bonded metal bridges
  • Metal, metal-ceramic crowns, Zirconia, FPD with sub-optimal preparation geometry
115
Q

Resin Cement:

Advantages:

A
  • High compressive and very high tensile strength
  • Resistant to water dissolution
  • Resistant to acid dissolution
  • Molecular adhesion to tooth and crown material (can enhance strength of ceramic restorations)
116
Q

Resin Cement:

Disadvantages:

A
  • Highly technique sensitive
  • Variable film thickness
  • Variable difficulty removing proximal and subgingival excess material
  • Marginal leakage due to polymerization shrinkage
  • Postoperative sensitivity varies with materials and technique
117
Q

Preparation of Restoration for cementation:

A
  • Metal - Sandblast fit surface – 50 microns AL2O3
  • Indirect composite – HF acid etch
  • Glass Ceramics - HF etch (timings Emax (L) – 20s, Empress(LD) – 1min) + silane treatment
  • Zirconia(YTZP), Procera (Alumina)–Retentive prep– non-adhesive cement needs no treatment
  • Zirconia(YTZP), Procera (Alumina) – Unretentive prep – adhesive cement needs protein removal followed by Monobond primer.
118
Q

Temporary cements:

Eugenol containing:

Formulation:

Application:

A
  • Formulated as a powder-liquid or two-paste system
  • Powder or Base Paste: zinc oxide particles Liquid or
  • Accelerator Paste: eugenol
  • Slow but proceeds more rapidly in a warm, humid environment
  • Application: for provisional applications
119
Q

Residual free eugenol interference:

A

Residual free eugenol interferes with the proper setting of resin-based composites or resin cements.

120
Q

Permanent cements:

A
  • Zinc phosphate
  • Zinc polycarboxylate
  • Glass ionomer (GI)
  • Resin modified glass ionomer (RMGI)
  • Resin cements
121
Q

GI cement:

applications:

A
  • Metal and Metal-Ceramic Restorations
  • Porcelain restorations
  • All Ceramic Crowns with high strength cores such as alumina or zirconia
122
Q

GI cement:

Advandages:

A
  • Adhere to teeth and metal
  • Fluoride release
  • Ease of Mixing
  • Good flow
  • Cheap
  • Aesthetic
  • Thermal compatible with enamel
  • Low shrinkage
  • Good resistance to acid dissolution
123
Q

GI cement:

Disadvandage:

A
  • Soluble in water
  • Rapid set – time limitation especially in cementation of several units.
  • Moisture sensitivity at set
  • Brittle
  • Low fracture toughness
  • Poor wear resistance
  • Radiolucency
  • Possible pulpal sensitivity
124
Q

Resin modified glass ionomer (RMGI):

Application:

A
  • Core buildups
  • Luting cements
  • Crowns
125
Q

Resin modified glass ionomer (RMGI):

Not used for:

A
  • All-ceramic crowns – due to uptake of water causing swelling and pressure on the crown
  • Veneer – not retentive enough
126
Q

Resin modified glass ionomer (RMGI):

Advandages:

A
  • Dual cure
  • Fluoride release
  • Higher flexural strength than GI
  • Capable of bonding to composite materials
127
Q

Resin modified glass ionomer (RMGI):

Disadvantages:

A
  • Setting expansion may lead to cracking of all- ceramic crowns
  • Moisture sensitive
128
Q

Resin cements:

Application:

A
  • All crown types
  • Inlays
  • Veneers
  • Resin-fiber posts
129
Q

Resin cements:

NOT for:

A
  • If a ZOE cement has been used for the previous temporary.
  • Light cured under a metal crown since it would not cure through the metal.
130
Q

Resin cements:

Advandages:

A
  • Strongest of the cement – highest tensile strength.
  • Least soluble (in oral fluids)
  • High micromechanical bonding to prepared enamel, dentin, alloys, and ceramic surfaces
  • Neutral pH
131
Q

Resin cements:

Disadvandages:

A
  • Setting shrinkage – contributing to marginal leakage
  • Difficult sealing
  • Requires a meticulous and critical technique
  • Possible pulpal sensitivity
  • Difficult to remove excess cement
132
Q

Tooth Surface Loss:

The Three reasons for intervention in toothwear cases:

A
  • Loss of function
  • Sensitivity / Pain
  • Altered appearance
133
Q

Different types of TSL:

A
  • Attrition
  • Abrasion
  • Erosion / Acid dissolution
  • Abfraction
  • Caries
  • Iatrogenic
  • Trauma
134
Q

Attrition:

A
  • ‘wear caused by endogenous material such a microfine particles of enamel prisms caught between two opposing tooth surfaces’. Wear caused by tooth to tooth contact.
  • Signs: Flattening of cusp tips or incisal edges** with associated **wear facets on occlusal or palatal surfaces,** **Horizontal wear**, **Wear or facets on restorations, associated with TMD so patient may be complaining of pain and hypertrophy of masseter muscles.
135
Q

Abrasion:

A
  • ‘the wearing of tooth substance that results from friction of exogenous material forces over the tooth surface’. Usually wear due to overzealous brushing.
  • Signs: seen at the cervical margin of teeth where the enamel is thin and formed in a less regular pattern, can be seen as indentations, most susceptible teeth are upper canines** and **premolars.
136
Q

Acid Dissolution / Erosion:

A
  • ‘progressive loss of tooth substance by chemical processes**, that does **not involve bacterial action, producing defects that are sharply defined**, **wedge- shaped depressions often in facial and cervical areas’.
  • Extrinsic: Dietary (erosive foods, drugs, Vit. C), Environmental (exposure to acids in work such as battery factory workers).
  • Intrinsic: Pathological (cancer, morning sickness, Hiatus hernia, Peptic ulcers, Gastro-Oesophageal Reflux Disease (GORD), Self-induces (Anorexia nervosa, alcoholism)
137
Q

Acid Dissolution / Erosion:

Signs:

A
  • Tooth surface loss not involved in articulation
  • Cupping of incisal edges or cusps tips
  • Smooth Rounded polished lesions with a rim of enamel left around the tooth (known as perimolysis).
  • Restorations can be standing proud of tooth structure
  • The wear is smooth and rounded and often shiny.
138
Q

Acid Dissolution / Erosion:

Extrinsic wear:

A

The buccal surfaces are worn on the upper anterior and the occlusal and palatal surfaces of the posteriors

  • It is not the pH of the acid per se that causes the dissolution but the titratable acidity.
  • The titratable acidity is the amount of alkali needed to bring an acid up to neutral pH and indicates the strength and erosive potential of drinks,
  • The frequency of consumption is also an important factor
139
Q

Acid Dissolution / Erosion:

Intrinsic wear:

A

The palatal surfaces of the upper anteriors are worn and the occlusal surfaces of the posteriors.

140
Q

Abfraction:

A
  • Due to excess force transmitted to the cervical area from biting. There is an increase in stress at the cervical area and that the tooth undergoes a barrelling effect under this stress which may in turn break away the thin cervical enamel and cause a lesion similar to abrasion.
  • Signs: V-shaped cavities are formed cervically
141
Q

Extrinsic causes of Acid dissolution / Erosion:

A
  • It is not the pH of the acid per se that causes the dissolution but the titratable acidity.
  • The titratable acidity is the amount of alkali needed to bring an acid up to neutral pH and indicates the strength and erosive potential of drinks,
  • The frequency of consumption is also an important factor
142
Q

Over-extended margin:

A
  • Poor Impression
  • Surplus untrimmed wax or ceramic
  • Improperly trimmed die
143
Q

Under-extended margin:

A
  • Poor impression
  • Over-polished casting
  • Improperly trimmed die
  • Difficulty identifying finish line
144
Q

Over-Contoured (thick):

A

▪ Over-waxed

145
Q

Open Margin:

A

▪ Casting not completely seated

▪ Poor impressions

▪ Incomplete casting

▪ Improperly trimmed die

▪ Over-polished casting

146
Q

Evaluating the crown prior to cementation:

A

I. Proximal Contacts – use floss to check

II. Marginal Fit – use an explorer to check

III. Aesthetics – Check both shape and shade

IV. Occlusion – Check using GHM articulating paper

The order is important as if the proximal contacts are too tight then it will be impossible to assess the rest.

147
Q

Contraindications for All Ceramic Restorations:

A

➢ Teeth with large pulp space, such as your teeth • Adequate tooth reduction is likely to cause pulpal exposure ➢ Bruxist • Porcelains may be sheered off under excessive occlusal forces. • Can be abrasive on opposing teeth

148
Q

Preparation of All Ceramic Crowns General Principles :

A
  • Heavy chamfer or rounder shoulder margins
  • Rounded inner line angles
  • No sharp edges
  • Flattened occlusal surface for posterior teeth
149
Q

When to manage soft tissues?

A
  • Before the crown preparation - Ensure healthy periodontium.
  • At Crown preparation stage – Supragingival / Equigingival / Subgingival margins.
  • When constructing the provisional crown - Good adaptation of the provisional crown to the tooth preparation margins (no overhangs, no open margins and smooth finish)

➢ At Impression stage - Subgingival preparations need gingival retraction:

  • To prevent bleeding (haemostasis),
  • To act as a physical barrier and retract the gingival tissues, To allow an accurate impression of the preparation margins
150
Q

Soft Tissue Retraction:

A

Aim: To allow reproduction of the entire preparation

Criteria

➢ Effective gingival displacement

➢ Haemostasis

➢ No irreversible damage

➢ No systemic effects

151
Q

Occlusal Scheme: Mutually protected occlusion (also known as Canine Guidance)

A

– This is ideal occlusion in dentate individuals - is ‘an occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximal intercuspal position, and the anterior teeth disengage the posterior teeth in all mandibular excursive movements.

152
Q

Occlusal Scheme: Bilateral Balanced Occlusion:

A

Used in complete denture cases - This scheme involves contacts on as many teeth as possible (both on the working and non- working side) in all excursive movements of the mandible.

153
Q

Occlusal Scheme: Unilateral Balanced Occlusion:

A

Making contact with more than one tooth when you move your jaw in a sideways motion. Is known as group function, it is second to canine guidance.

154
Q

The Dahl Concept:

A
  • The work of Bjorn Dahl in the 80s / 90s demonstrated that when teeth are not in occlusion they have a tendency to move until the occlusion is re-established – He found this through the placement of a flat anterior bite plane in the ‘non-growing’ adult patient.
  • Can be used when we have extensive TSL** and **need to open up (increase the OVD) the bite to provide space for restorations
  • This usually involves **adding a restorative materia_l (eg. Composite Resin) or a _removable appliance on the anterior teeth_ and _leaving the posterior teeth apart**. The reverse is also possible. In 96% of the cases the teeth will move so that the posterior teeth meet.
  • The posterior teeth will extrude, and the anterior teeth will intrude in or order for the occlusion to be re-established.
  • Intrusion can be on average 1.05mm and extrusion 1.47mm. This can take up to 6 months.
155
Q

Table:

Preparations:

A
156
Q

Tooth reductions:

A
157
Q

Materials used for constructing chairside T/P:

A
  • Poly vinyl ethyl methacrylate - Trim
  • Poly ethyl methacrylate –Snap
  • Bis acryl composite – Protemp II, Quicktemp
  • VLC urethane dimethacrylates –Triad
  • Poly methyl methacrylates –Duralay
158
Q

Use of prefabricated crowns:

T/P:

A
  • This method is quick and easy.
  • For anterior teeth Polycarbonate crowns and Celluloid crown formers are used
  • For posterior teeth similarly polycarbonate and celluloid crowns can be used or metal aluminum crowns, which are not directly visible and therefore do not create aesthetic problem.
  • It is difficult to achieve a result with great precision
159
Q

Laboratory Fabricated Crowns:

T/P:

A

Usually made from PMMA or Composite resin

160
Q

Chairside Provisionals (Made by dentist):

T/P:

A
  • In the past their main disadvantage was that the material used was acrylic that would set with an exothermic reaction that was harmful to the tooth.
  • Now Bis acryl is the main material of choice.
  • Also, the aesthetic results are clearly inferior compared to lab fabricated provisionals.
161
Q

Alginate:

properties:

A
  • Good detail
  • It is faster at higher temperatures
  • Elastic enough to be pulled over the undercuts without deforming
  • Unstable during storage due to water lost
  • Non-toxic and non-irritating
  • Setting time may be dependent on how we use it
  • Alginate dust is unstable when stored in humidity or at high temperatures
162
Q

Polyethers:

Chemistry:

A
  • Base paste: Polyether, Filler
  • Catalyst paste: Sulphonic acid ester, inert oils
163
Q

Polyethers:

Advantages-Disadvantages:

A
164
Q

Alginate:

Advantages-Disadvantages:

A
165
Q

Polysulphide:

Application:

A
  • Crowns
  • Bridges
  • Partial dentures
  • Dentures
  • Implants
166
Q

Polysulphide:

A
167
Q

Polysulphide:

Advantages-Disadvantages:

A
168
Q

Silicones:

Classification:

A
  • Condensation silicone
  • Addition silicone
169
Q

Condensation silicones:

Chemistry:

A

Comes as a paste and liquid or two pastes

  • Base paste:
  • Silicone polymer with terminal hydroxyl groups
  • Filler
  • Catalyst paste:
  • Silaxone
  • Activator
170
Q

Condensation silicones:

A
171
Q

Addition silicones:

Chemistry:

A
  • They come in 2 pastes or a pistol and cartridge form as a thin, medium, thick and very thick
  • Paste: contains a polydimethyl siloxane polymer with which some methyl groups are replaced by hydrogen
  • The other paste: contains prepolymer of vinyl groups, it also contains a catalyst
172
Q

Addition silicones:

Advantages-Disadvantages:

A

Avoid: Latex gloves-> inhibit the setting of the material

173
Q

Dual cord technique:

Method:

Aim:

Disadvantage:

A
  • Involves two impregnated cords packed into the sulcus.

Method:

  • The smaller sized cord is placed first and remains in the sulcus during the impression stage.
  • A larger cord is placed on top – in the same stages as described in the previous slides.

Aim:

  • The smaller cord reduces the risk of the gingival cuff recoiling and displacing partially set impression material.

Disadvantage:

  • Increased inflammation and tissue damage.
174
Q

Retraction paste:

Method:​

Advantages:

Disadvantages:

A
  • Gingival retraction pastes can be used to create space between the prepared tooth and the sulcus.
    Some are medicated with e.g. Aluminium Chloride.
    The material is viscous and maintains rigidity, displacing the gingivae away from the tooth without causing trauma.

Method:

  • Express it around the preparation, directly in the sulcus.
  • Leave for 2 mins, then wash away with water, dry the tooth and take the impression.

Advantages:

  • Quicker and seems easier than using retraction cord and astringent.

Disadvantages:

  • Can be technique sensitive with a suboptimal result.
175
Q

Rotary curettage:

Aim:

Advantage:

Disadvantage:

A

Aim:

  • The limited removal of sulcular epithelium with rotary instruments while preparing the marginal finish line.

Advantage:

  • Quick

Disadvantage:

  • Trauma and haemorrhage with poor healing.
  • Increased risk of periodontal destruction.
176
Q

Electrosurgery:

Aim:

Use:

Contraindications:

A

Aim:

  • Controlled tissue destruction from a current flowing from a small cutting electrode (wire) that produces a high current and temperature at the point of contact with the tissue.
  • High frequency electrical currents cut and/or coagulate soft tissues and have interchangeable electrode tips of different configurations.

Use:

  • When the situation may not be feasible or desirable to manage the gingivae with retraction cord along (gingival hyperplasia).
  • Widening of the gingival sulcus, coagulation, gingivectomy.

Contraindications:

  • Do NOT use on patients with cardiac pacemakers
  • Do NOT use with topical anesthetics or flammable aerosols.
177
Q

Crown Lengthening:

Definition:

Advantages:

Disadvantages:

A

Definition:

  • This is a surgical procedure involving bone removal and gingival re-contouring.

Advantages:

  • Increase crown height and retention
  • Create supragingival margins
  • Improve aesthetics

Disadvantages:

  • Discomfort
  • Finish line on root surface cementum (bonding issues)
  • Furcation involvement on molar teeth (issue with cleaning) o Increased crown: root ration
  • Need to allow time for healing
178
Q

Soft tissue management:

Methods:

A
179
Q

RBB:

Pontic Shape:

A
  • Ovate is the ideal
  • Modified ridge lap is useful if there are potential problems with height
180
Q

RBB:

Rigid Connector:

A
  • Nickel Chromium
  • Minimum thickness 0.7mm
  • 180 wraparound
  • Connector Height 3mm
  • Avoid bikinis
181
Q

RBB:

Indications:

A
  • Patients with sound abutment teeth and occlusion well controlled
  • And with good OH
  • Hypodontia cases (not microdontia)
  • Neighbouring teeth are non-restored
  • Maxillary incisor replacement and mandibular incisor replacement (most favourable prognosis)
  • Single posterior tooth replacement
182
Q

RBB:

Contraindications:

A
  • When the abutment teeth are heavily restored – the presence of restorations is not an absolute contra-indication, but where large amounts of the functional surfaces of the abutment teeth consist of restorative material, conventional retainers may be a better option
  • Lack of clinical crown height in the abutment teeth
  • Teeth periodontally involved (with extensive bone loss) – increased
  • functional loading on such teeth can lead to increased rate of periodontal
  • destruction
  • Significant bruxism / parafunctional activity
183
Q

Fixed Partial Denture (Conventional Bridges)

The Four Basic Bridge Designs:

A
  • Fixed-fixed bridge.
  • Fixed- supported (movable )
  • Fixed-free bridge or Cantilever bridge Spring cantilever bridge.
  • Combinations
184
Q

Fixed Partial Denture (Conventional Bridges):

Fixed-fixed Bridge:

A

A fixed-fixed bridge has a rigid connector at both ends of the pontic. This is a minimum of three units and cemented in one piece

185
Q

Fixed Partial Denture (Conventional Bridges):

Fixed- supported (movable) Bridge:

A

A fixed-movable bridge has a rigid connector, usually at the distal end of the pontic, and a movable connector that allows some vertical movement of the mesial abutment tooth.

186
Q

Fixed Partial Denture (Conventional Bridges):

Cantilever Bridge:

Advantages:

Disadvantages:

A
  • A cantilever bridge is a fixed partial denture that attaches to adjacent teeth on one side of the bridge only.

Advantages:

  • The most conservative design when only one abutment tooth is needed.
  • Construction in the laboratory is relatively easier
  • Most suitable in replacing anterior teeth, where there is little risk of the abutment tooth tilting.

Disadvantages:

  • The length of span is limited to one pontic.
  • The construction of the bridge must be rigid to avoid distortion.
  • Occlusal forces on the pontic of small posterior bridges encourage tilting of the abutment tooth.
187
Q

Spring Cantilever Bridge:

A
188
Q

Fixed Partial Denture (Conventional Bridges):

Pontic shape:

A

Hygienic/sanitary:

  • This type is readily cleansable and great for the health of the tissue, but not at all esthetic.

Ridge lap:

  • This type is designed to look like a saddle. It laps over both sides of the ridge like a saddle thrown over the back of a horse. It’s fairly esthetic but not cleansable, and it can result in chronic tissue irritation.

Modified ridge lap:

  • This type is designed so that the saddle laps over the buccal side only.
    The shape and size of the ridge and restoration dictate the lingual design. It curves in and leaves the lingual ridge exposed. It is fairly esthetic and more cleansable than the full ridge lap.

Bullet/conical:

  • rounded and cleanable smaller tip in relation to overall size

Ovate:

  • This type is designed to look like an egg or bullet. It is ideal for anterior teeth; however, it’s not limited for posteriors as it is highly esthetic and cleansable. It is developed by a depression created in the residual tissue ridge that mimics the shape of the natural root and crown. The tooth looks as if it is growing out of the gum tissue and not just resting on top of it. If you demand the best esthetics available, and the least maintenance, the ovate pontic is the best choice.
189
Q

Luting metallic restorations and posts:

A

Conventional glass ionomer and zinc phosphate cements are among the most popular materials for luting metallic restorations and posts

190
Q

esthetic applications:

A

resin-based cements are preferred for esthetic applications.

191
Q

BEWE:

A
192
Q

Guidance using BEWE cumulative risk score:

A
193
Q

Mobility assessment

A
194
Q

Furcation Assessment:

A

Dentistry-5th semester (9 decks)

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