Crash Course in Fixed Prosthodontics
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Questions and Answers

What can occlusal problems lead to?

Tooth wear, fracture of tooth or restoration, restoration de bonding, bone resorption, gingival recession, tooth mobility, PDL sensitivity and pain.

What indicates an ideal bite in static occlusion?

Equal contacts on all cusp tips and fossa with heavier contacts posteriorly.

In dynamic occlusion, lateral excursion refers to moving the jaw to the ______ and ______.

right, left

Which of the following techniques is used to examine the location of contact points?

<p>Articulating paper</p> Signup and view all the answers

What should you do before making any restoration?

<p>Perform occlusal analysis.</p> Signup and view all the answers

What factors are assessed in the periodontal considerations during tooth restorability evaluation?

<p>All of the above</p> Signup and view all the answers

What is the definition of the ferrule effect?

<p>A ring of remaining tooth structure that provides resistance to displacement in the coronal direction.</p> Signup and view all the answers

What are some endodontic considerations when assessing tooth restorability?

<p>Ease of RCT and post placement, check for curved canals, calcified canals, root resorption, root fracture/perforation, PA lesions.</p> Signup and view all the answers

Premature contacts are caused by low cusps.

<p>False</p> Signup and view all the answers

What can be added to hybrid ceramics to improve their properties?

<p>Composite</p> Signup and view all the answers

What is the strongest material used in dental ceramics?

<p>Zirconia</p> Signup and view all the answers

Which of the following is a disadvantage of all ceramic restorations?

<p>Reduced strength</p> Signup and view all the answers

Porcelain layering includes Opaque, Dentine, and ______.

<p>Incisal</p> Signup and view all the answers

What thickness is needed for incision reduction in all ceramic anterior crown preparation?

<p>2 mm</p> Signup and view all the answers

What causes the porcelain to bond to the metal in metal-ceramic restorations?

<p>All of the above</p> Signup and view all the answers

All ceramic restorations do not require any supporting metal structure.

<p>True</p> Signup and view all the answers

What should be done before cementing thin ceramics anteriorly?

<p>Just air spray the bonding agent and don't cure it before cementing.</p> Signup and view all the answers

Match the following ceramics with their thickness requirements:

<p>Opaque porcelain = 0.2 mm Body porcelain = Bulk of the restoration Enamel porcelain = Provides translucency Porcelain-metal junction = At least 0.5 mm thick</p> Signup and view all the answers

What factors should be considered for a patient before dental treatment?

<p>Patient has systemic disease or risk factors like smoking.</p> Signup and view all the answers

The width of the remaining wall for Class 1 ferrule should be at least ____ mm for aesthetic margin.

<p>≥ 2.2</p> Signup and view all the answers

The ideal height of remaining tooth for Class 1 ferrule is ____ mm.

<p>≥ 2</p> Signup and view all the answers

Which treatment option is NOT a way to gain retention for extensively damaged teeth?

<p>Routine cleaning</p> Signup and view all the answers

When should you decide to crown a tooth?

<p>When there is insufficient ferrule and large contact restoration is not feasible.</p> Signup and view all the answers

A patient with adequate tissue support is a good candidate for a removable partial denture (RPD).

<p>True</p> Signup and view all the answers

What is a consequence of losing balanced occlusion?

<p>Tilted teeth can cause occlusal interferences.</p> Signup and view all the answers

Match the bridge classifications to their descriptions:

<p>Conventional = Removes tooth structure and replaces it with a retainer Minimal prep = Uses wings and preserves natural tooth structure Hybrid = Combines conventional and minimal prep Cantilever = Provides support at one end only</p> Signup and view all the answers

What are indications for implants?

<p>Inadequate number of abutment teeth, strength to support conventional FPD.</p> Signup and view all the answers

Combining an implant and a natural tooth is recommended.

<p>False</p> Signup and view all the answers

What is necessary for checking the taper of a preparation?

<p>Looking for all margins with one eye from a distance of 30 cm.</p> Signup and view all the answers

The optimum crown-to-root ratio is ____.

<p>2:3</p> Signup and view all the answers

Which finish line is used in all metallic restorations?

<p>Chamfer</p> Signup and view all the answers

What is the depth range for a chamfer finish line?

<p>0.3 – 0.5 mm</p> Signup and view all the answers

What is the most destructive type of finish line?

<p>Shoulder</p> Signup and view all the answers

What materials can be used to layer the metal in prosthodontics?

<p>All of the above</p> Signup and view all the answers

A beveled shoulder margin is used when gingival esthetics are not critical.

<p>True</p> Signup and view all the answers

Match the ceramic types to their characteristics:

<p>Feldspathic = Most conservative and most translucent ceramic Leucite = Strong material utilized for its thermal expansion properties Lithium Disilicate = Strong and very translucent material Zirconia = Highest strength with no glass matrix</p> Signup and view all the answers

What should the connector thickness be for PFM bridges?

<p>Minimum 3 mm</p> Signup and view all the answers

The depth for heavy chamfer finish line is ______.

<p>1 mm</p> Signup and view all the answers

What material is primarily used for dental implants?

<p>Porcelain</p> Signup and view all the answers

What type of ceramic is indicated when less than 50% of enamel remains?

<p>Zirconia-reinforced Lithium Disilicate</p> Signup and view all the answers

What are the two main ways ceramic can be fabricated?

<p>Mix powder + liquid or use a block/ingot of ceramic</p> Signup and view all the answers

What structure should you choose towards the midline when determining a patient's midline?

<p>the nose or the philtrum</p> Signup and view all the answers

What is the indication for using PFM over all ceramic for long span bridges?

<p>Better longevity in certain applications</p> Signup and view all the answers

What length should the maxillary incisors be established by?

<p>anterior guidance and phonetics</p> Signup and view all the answers

What is the position of lower incisors in relation to the maxillary incisors when saying the letter S?

<p>1 mm behind and 1 mm below</p> Signup and view all the answers

Which of the following is a contraindication for using PFM crowns?

<p>Heavy discolorations</p> Signup and view all the answers

What type of smile line exposes all of the anterior teeth plus soft tissues?

<p>High smile line</p> Signup and view all the answers

For posterior PFM crowns, the functional cusp should be reduced by ____ mm.

<p>2 mm</p> Signup and view all the answers

Older patients tend to have high smile lines.

<p>False</p> Signup and view all the answers

What type of preparation should be used for anterior PFM crowns?

<p>Depth guiding grooves, incisal and buccal reduction</p> Signup and view all the answers

The height to width ratio in the golden proportion is _____ (value).

<p>0.618</p> Signup and view all the answers

All ceramic bridges have a higher risk of fractures compared to PFM bridges.

<p>True</p> Signup and view all the answers

Match the following statements regarding veneers with their descriptions:

<p>Direct veneers = Composite material Indirect veneers = Porcelain, acrylic resin, gold Advantages of composite veneers = Simple and quick application Disadvantages of composite veneers = Cannot mask deep discolorations</p> Signup and view all the answers

What does metamerism refer to?

<p>The object will look differently under different light sources</p> Signup and view all the answers

What is a common disadvantage of using indirect veneers?

<p>Requires high skills and is time-consuming</p> Signup and view all the answers

Which shade guide is the only one approved by the ADA?

<p>Vita Pan 3D Master</p> Signup and view all the answers

What is the aesthetic consideration mentioned for shade selection?

<p>Diagnostic wax up and mock ups for patient expectation</p> Signup and view all the answers

What should be done to prevent eye fatigue when choosing the shade of restoration?

<p>Choose the shade at the beginning of the appointment</p> Signup and view all the answers

What affects the choice of posts when restoring a tooth?

<p>All of the above</p> Signup and view all the answers

When preparing veneers, sufficient interproximal clearance is needed to place a _____ between adjacent teeth.

<p>mylar strip</p> Signup and view all the answers

The final color of the veneer is affected equally by the porcelain color and the cement color.

<p>False</p> Signup and view all the answers

Parallel-sided posts are more retentive than tapered posts.

<p>True</p> Signup and view all the answers

What is the recommended post length compared to the remaining coronal height?

<p>Posts should be as long as possible without jeopardizing the apical seal</p> Signup and view all the answers

The optimal post diameter should not be greater than _____ of the diameter of the root.

<p>1/3</p> Signup and view all the answers

What is one advantage of having a post and core alone rather than a crown in one piece?

<p>Better marginal adaptation</p> Signup and view all the answers

Study Notes

Occlusion Examination

  • Occlusal problems can result in tooth wear, fractures, restoration debonding, bone resorption, gingival recession, and tooth mobility.
  • Ideal static occlusion (ICP/MI) requires equal contact on all cusp tips, with heavier contacts posteriorly.
  • Premature contacts are caused by high cusps; deflective contacts occur from large cusps affecting mandibular movement.
  • Use articulating paper (40 µm) for contact points and shimstock to assess contact heaviness.
  • In dynamic occlusion, lateral excursion should show no working or non-working side interferences, except in complete denture patients.
  • Protrusion analysis should have even contacts on anterior teeth and no posterior interferences, with adjustments avoided to prevent creating new interferences.

Assessing Tooth Restorability

  • Begin with the removal of all caries and previous restorations.
  • Evaluate remaining tooth structure, focusing on the ferrule effect both vertically and horizontally.
  • Assess the crown-root ratio for structural integrity.
  • Consider endodontic factors such as the complexity of root canal treatments, root canal morphology, and any pathogenic conditions affecting roots.
  • Review periodontal health, including pocket depth, clinical attachment loss, bone loss, mobility, and presence of endodontic-periodontal lesions.### Patient Factors
  • Presence of systemic diseases or risk factors like smoking impacts treatment choices.

Ferrule Effect

  • Vertical measurement: Distance from the gingival margin to the top of the remaining wall measured using a probe at four locations (buccal, lingual, mesial, distal).
  • Ideal Class 1 ferrule requires remaining tooth height of ≥ 2 mm.
  • Class 2 ferrule acceptable with height of 0.5–2 mm, especially with post and core.
  • Class 3 ferrule unacceptable with height < 0.5 mm.

Horizontal Ferrule

  • Measurement at future crown margin level using gauge calipers or a probe.
  • Minimum wall thickness must be preparation thickness + 1 mm.
  • Aesthetic margin (AM) for metal-ceramic or all-ceramic; non-aesthetic margin (nAM) for metal only.
  • Class 1: Wall width ≥ 2.2 mm (AM) or ≥ 1.5 mm (nAM).
  • Class 2: Wall width ≥ 1.5 mm (AM) or ≥ 1 mm (nAM).
  • Class 3: Wall width < 1.5 mm (AM) or < 1 mm (nAM).
  • Margins: Chamfer width = 0.5 mm; Shoulder width = 1.2 mm.

Tooth Retention and Resistance

  • Extensively damaged teeth can gain retention through ortho extrusion, crown lengthening, or RCT with post and core.
  • Note: Ferric sulfate and aluminum chloride astringents can negatively affect bond strength of composite to dentin. Rinse with water if contact occurs.

Crown Decision Factors

  • Crown placement is indicated when:
    • Direct restoration is inadequate.
    • Axial surfaces are weakened or restored.
    • Tooth serves as an abutment for a bridge.
    • Risk of tooth fracture is high.
  • Subgingival margins may be necessary, but caution is required regarding biological width and impression quality.

Diagnosis & Treatment Planning for Restoration

  • Comprehensive patient assessment includes medical history, clinical examination, and radiographs.
  • Consider options: nothing, RPD, implants, FPD.
  • Need to understand why to replace missing teeth: functional and esthetic restoration, occlusal stability, etc.

Bridge Classification Based on Preparation

  • Conventional: Tooth structure is removed and replaced with a retainer.
  • Minimal Preparation: Resin bonded bridge or Maryland bridge, preserving intact abutments.
  • Hybrid: Combination of conventional and minimal prep retainers.

Treatment Planning for Missing Teeth

  • Replace missing teeth options: implant, RBB, cantilever, 3-unit bridge.
  • Dynamic equilibrium disrupted by tooth extraction may lead to further dental issues.
  • Tilted teeth may cause occlusal interferences, requiring adjustments.

RPD and FPD Indications

  • RPD: Indicated for cross-arch stabilization, bilateral spaces, ridge support.
  • FPD: Indicated for a few missing posterior teeth, favorable abutments, and good inter-arch space.
  • Avoid RPD in patients with tongue issues or xerostomia; avoid FPD in caries-active or periodontal diseases patients.

Resin Bonded Bridges

  • Suitable for single missing incisor or premolar; typically temporary.
  • Contraindications: deep bites, short clinical crowns, misaligned abutments.

Implants - Indications and Considerations

  • Implants suitable when inadequate abutment teeth exist.
  • Caution in combining implants with natural teeth due to differing responses to occlusal forces.
  • Vertical forces are preferable for implants for better load distribution.

Abutment Assessment for Bridges

  • Radiographs essential for evaluating periodontal support, pulp health, and restorability.
  • Low crown-root ratios (C:R) acceptability may apply in specific conditions.

Biomechanical Principles of Tooth Preparation

  • Conservation of tooth structure is paramount; excessive removal leads to complications.
  • Retention affected by taper, length, and freedom of displacement parameters.
  • Marginal integrity and structural durability of restoration are crucial for longevity and health.

Finish Lines

  • Various types: Knife edge (conservative but plaque-retentive), chamfer (moderate retention), and shoulder (provides rigidity).

These aspects are essential for successful fixed prosthodontic treatment planning and implementation.### Finish Lines

  • Chamfer finish line is used for all metallic restorations and the PFM's lingual portion; it's non-plaque retentive.
  • Heavy chamfer features a rounded internal angle and a 90-degree cavo-surface angle, mainly for ceramic restorations.
  • Shoulder finish line is employed in the facial portion of PFM and ceramic restorations, but the internal angle must be rounded.
  • Beveled margin eliminates unsupported enamel, allowing for better cast metal margins against tooth structure.
  • Knife edge is suitable for mandibular posterior teeth; it permits thin margins but is prone to distortion.

Common Mistakes in Finish Lines

  • Discontinuity and roughness can be rectified using an enamel hatchet.
  • Undercuts from improper taper can damage the margin.
  • Insufficient proximal clearance may lead to lab-related damage during die preparation.
  • Marginal lip occurs if the bur is inserted more than halfway into the margin.

Ideal Margin and Preparation Guidelines

  • Ideally, margins should be supragingival, positioned 0.5 mm away from the gingiva.
  • Complete stabilization phase including perio and caries control is required before restorations.
  • Functional cusps require 1.5 mm of reduction, while non-functional cusps need 1 mm; bevel the functional cusp at 45 degrees.
  • Lingual and proximal reductions should maintain a chamfer margin of 0.3-0.7 mm.

Dental Ceramics

  • Ceramics are used to veneer metal or zirconia cores, applied directly to teeth, and for dentures.
  • Porcelain contains feldspar, kaolin, and quartz.
  • Fabrication involves either mixing powder and liquid or using pre-formed blocks/ingots.

Types of Ceramic Fabrication

  • Sintering involves mixing powder and applying it onto a cast, followed by high-temperature firing.
  • Slip casting uses a refractory material to duplicate a master cast, helping the ceramic to separate post-firing.
  • Heat pressing and milling are other methods of creating ceramics.

Ceramics Strength and Aesthetics

  • Ceramic strength varies with melting temperature: high melting for blocks, low melting for PFM, and ultra-low for aesthetic adjustments.
  • Strength hierarchy: zirconia > lithium disilicate > feldspar; aesthetics hierarchy: feldspar > lithium disilicate > zirconia.
  • Predominantly glassy ceramics offer translucency; opaque ceramics are formed from polycrystalline materials.

Strengthening Brittle Ceramics

  • Techniques include glass infiltration, dispersion strengthening, and transformation toughening (specific for zirconia).
  • Glassy ceramics are preferable when shade matching is unnecessary; opaque ceramics mask discolorations.

Glass Ceramics

  • Feldspathic ceramics lie at the high end for translucency but have the lowest strength.
  • Leucite ceramics are stronger than feldspathic due to added potassium oxide, while lithium disilicate provides high strength and translucency.
  • Zirconia is the strongest option and is ideal when under 50% enamel remains.

Oxide Ceramics

  • Alumina-based ceramics incorporate high crystalline content for opaqueness and are layered with feldspar.
  • Zirconia ceramics, being 100% polycrystalline, are exceptionally strong but can damage opposing teeth.

Repairing and Adjusting Ceramics

  • Repair of chipped ceramics may involve using hydrofluoric acid, silane coupling agents, and bonding agents.
  • Adjustments to zirconia occlusion require sending restorations back for re-glazing.

Advantages and Disadvantages of All-Ceramic Restorations

  • Advantages include high aesthetics and translucency, allowing for shade modification.
  • Disadvantages consist of reduced strength due to brittleness, potential wear on opposing teeth, and the need for thicker connectors in bridges.
  • Indications revolve around high aesthetic demands, while contraindications include unfavorable occlusal loads and insufficient tooth structure.

Porcelain Layering Technique

  • Opaque layers (0.2 mm) mask the core color, dentine layers (1.5 mm) provide bulk, and incisal layers grant translucency.
  • Each shade change demands an extra removal of 0.2 - 0.3 mm.
  • Internal bleaching can be conducted prior to crown preparation on RCT teeth for better color matching.

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Crash Course In Fixed Prosthodontics PDF 2020

Description

This quiz covers essential concepts in fixed prosthodontics, including occlusion examination and assessing tooth restorability. Ideal for dental students and practitioners looking to refresh their knowledge in this specialized field. Test your understanding and apply these principles in practice.

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