Fixed & Removable Prosthodontics Exam Review

Course Information

• Course Title: Fixed & Removable Prosthodontics
• Course Code: DES410
• Faculty: Dr. Christos Theocharides and Dr. Alexandros Panayiotou
• Institution: European University Cyprus, School of Dentistry

Exam Format

• 20 multiple choice questions (MCQs): 10 fixed, 10 removable; each worth 1 mark. Each MCQ has 5 options, only one is correct.
• 10 short answer questions (SAQs): 5 fixed, 5 removable; each worth 4 marks.
• Questions are primarily clinical-based. Review year 3 notes and clinical guidelines for preparation.
• Carefully read each question before answering.

Dental Crowns

• Indications: Protect remaining tooth structure, alter aesthetics, facilitate removable partial denture construction, alter occlusal plane.
• Types (from least to most destructive): Zirconia (monolithic), all-metal crown, all-ceramic crown, ceramo-metal crown, porcelain fused to zirconia.

Tooth Reductions

• A table details reductions for different materials based on occlusal (posterior) and incisal (anterior) areas of the tooth.

Crown Preparation (Steps)

• Take shade of crown (if porcelain or zirconia).
• Take two or three putty indices.
• Apply local anesthetic if required.
• Prepare tooth (use guide indices).
• Fabricate temporary crown.
• Place retraction cord with a hemostatic agent.
• Take an impression.
• Place temporary crown.
• Check occlusion and adjust if needed.
• Complete records and laboratory card.

One Stage Impression Technique

• Select appropriate tray, apply adhesive to tray (following manufacturer's instructions).
• Ensure any undercuts in the mouth are blocked appropriately (using wax if needed).
• Have assistant load heavy-bodied material into the tray (using green/blue mixing tip).
• Simultaneously, use a syringe with light-bodied material (yellow mixing tip) to irrigate around the prepared teeth.
• Firmly hold the tray in the mouth until the impression sets. Do not leave it in too long to avoid trapping undercuts.
• Remove, rinse and disinfect following manufacturer's recommendations.

Inspection of Impression Quality

• Rinse and clean impression to remove saliva and blood.
• Dry and check using 3-in-1 tool and light/magnification.
• Disinfection according to manufacturer's instructions.
• Check preparation margins, tooth morphology, air bubbles.
• Ensure impression material is still attached to impression tray.
• Complete and submit lab form, signed by supervisor.

Crown Cementation (Steps)

• Verify lab work, including fit and shade.
• Remove temporary restoration.
• Clean the underlying prepared tooth.
• Try in the restoration.
• Check marginal fit, contact points, and occlusion.
• Verify patient's satisfaction with fit and appearance.
• Remove crown and clean both crown and tooth surfaces.
• Sandblast with aluminum oxide (50µm) if indicated.
• Cement with proper cement, remove excess.
• Recheck occlusion.

Cements or Luting Agents

Summarizes cements based on soft (temporary) versus permanent (hard) categories. Includes different types within each category, e.g., provisional restorations, acid-base reaction.

Choosing the Right Cement (Luting or Bonding)

• The weaker restoration material, the stronger the cement.
• Bonded cements disperse forces away from the interface.
• Correct amount of retention needed (preparation form, tapers, crown/wall length) is crucial.

Non-Silicate Ceramics (Zirconia)

• Zirconia-based components are difficult to bond to synthetic or natural tissues.
• Traditional adhesive techniques for silica-based ceramics do not work effectively with zirconia.
• Modifications to the surface of zirconia might improve adhesive bonding.

Physical Properties of Zirconia

• Zirconia's composition and physical properties differ from conventional silica-based materials (e.g., porcelain).
• Zirconia is not easily etched, requiring aggressive mechanical abrasion methods to improve surface roughness, possibly creating strength reduction flaws.

Recommended Cements for Zirconia Ceramics

• Resin cements containing 10-MDP (methacryloyloxydecyl dihydrogen phosphate) can chemically bond with zirconia.
• Examples include Panavia V5, SE Bond, or SA Luting.

Some Tips

• Avoid phosphoric acid contact with zirconia during cementation.
• Do not use prophy paste for cleaning tooth preparations. Use pumice and water.
• Use resin-modified glass ionomer (RMGI) cement for zirconia restorations when preparations have near-ideal characteristics.
• Ensure tooth preparation height (at least 4mm) from the gingival margin to the occlusal table.

Permanent Cements

• Provides a table categorizing permanent cements in terms of type and their applications/strengths/weaknesses.

Articulating Papers

• Used to check occlusal contacts in crowns, dentures, provisional, and definitive restorations.
• Explains different types of articulating papers regarding thickness and common uses.

Treatment Planning Process

• Describes a three-phase model: Emergency, Investigation/Stabilization, Rehabilitation, and Maintenance.

Clinical Case Scenario

A patient with severe decay and irreversible pulpitis on tooth #46 is described. The student needs to determine the management approach.

Emergency Phase

• Emergency cases (acute pain) entail either RCT or extraction (if unrestorable), especially if multiple carious cavities and active periodontal disease exist.

Stabilization Phase

• Treat carious cavities and stabilize periodontal disease.
• Complete RCT on tooth #46 in some cases.

Rehabilitation Phase

• Restoration focus on prosthetic stage and restoring all affected teeth.

Maintenance Phase

• Set patient recall intervals for checkups and hygiene.

Common Errors Affecting Marginal Fit

• Tight proximal contacts.
• Casting blebs.
• Over/under-extended crown margins.
• No die spacer.
• Impression distortion.

Checking the Fit of the Crown

• Visual: Check margins (directly or with mirror), use magnification.
• Instrumental: Use explorer probes with different sizes and angles of approach for subgingival margins.

Types of Defective Margins

Describes different types of poor marginal fits, including over-extended, under-extended, over-contoured, and open margins.

Evaluating the Crown Prior to Cementation

• Check proximal contacts (use floss).
• Check marginal fit (use explorer).
• Check both shape and shade.
• Check occlusion (use articulating paper).

Semi-Precision Attachments

• A section on semi-precision attachments.

Objectives of Modifying Abutment Tooth Contours

• Develop a suitable path of insertion.
• Promote favorable biomechanical properties.
• Improve aesthetics.
• Improve structural durability.

Options for Replacing Teeth

• Describes several common options (fixed, removable).
• Includes examples of different materials/designs used in these approaches.

Factors Affecting Prognosis of Teeth

• Patient Factors: Restorative (endodontic, periodontal, and structural), medical, dental and social factors, expectations, financial status, behavior.
• Dentist Factors: Experience, skills, training, available materials & equipment.

Prognosis

• Structural Integrity: Requires at least 1.5mm ferrule, and dentin needs more than 1mm thickness, especially for root-treated teeth.
• Endodontic Integrity: Predictable outcomes require healthy pulps/clean/obturated root canals.
• Periodontal Integrity: Bone loss and tooth mobility influence prognosis.

Strategic Value of a Tooth

• Aesthetics, medical, occlusal, prosthodontic, functional, and financial impacts.

RCP and ICP

• RCP: Bilateral, unstrained mandible position where tooth-to-tooth contact occurs/reproductive position for the occlusion when restoring multiple units.
• ICP: Position of most tooth-to-tooth contact for individual's occlusion.

Management of Teeth with Extensive Tooth Loss

• An overview of management strategies.

Toothwear

• What to check in a clinical exam (Presenting complaint, medical history, social history, diet history, extra-oral and intra-oral exam, wear identification, sensitivity tests, radiographs, prosthodontic assessment.

Types of Tooth Surface Loss

• Attrition, abrasion, erosion, abfraction, caries, iatrogenic, and trauma.

How to Manage Wear Cases

• Questions addressed: What type of wear? Treatment approach? If restoring shape, plans, materials used, and need for splints. Types and function of splints.

Clinical Features of Attrition and Erosion

• Attrition: Flattening of cusps, wear facets, fractures, hypersensitivity, surface loss not related to articulation, possible masseteric hypertrophy/tenderness.
• Erosion: Smooth/shiny enamel loss, deep cupping.

Management of TSL

• A summary of management options ordered from most to least conservative.

How to Manage a Patient with TSL from Erosion - most conservative to most destructive

• Diet analysis and change recommendations.
• Fluoride toothpaste and teeth protection recommendations.
• Composite resin restorations are a key repair option for function and aesthetics.
• Indirect lab-made restorations can restore worn-down teeth.
• Splints are not recommended for active erosion cases.

How a Wear Case is Managed

• Take articulated study casts in centric relation (CR).
• Fabricate wax-ups.
• Demonstrate the wax-up/restoration to patient.
• Make a putty index or plastic retainer.
• Use composite resin to restore the upper anterior teeth.

Role of Splints

• To test an increase in occlusal vertical dimension, in case of TMD, before and after restorative therapy.
• To evaluate patient positioning in RCP (Centric Relation Position).
• To treat TMD patients with muscle origin pain.
• To assess patients who may use partial dentures/overdentures/onlays.

Posts and Cores

• Post: A metal or rigid material placed in the root canal of a non-vital tooth to support a dental restoration.
• Core: A substructure replacing missing coronal tooth structure that supports the final restoration.
• The presence of sufficient natural tooth structure helps anchor a dental. If suitable, no post needed.

How to Decide on Post Type: Direct/Indirect

• Guide for determining the best option (direct or indirect) based on ferrule height.

Differentiating Indirect and Direct Methods

• Indirect: Post/core fabrication in the lab, often using a cast post.
• Direct: Post/core fabrication at the chairside, often involving fiber composite material.
• Indirect Method: Wax or duralay representation is sent to lab for fabrication

Questions: What is ideal length of a post?

• A guide about how to select the ideal post length related to ferrule and the amount of dentin remaining.

Tooth Restorability Index (TRI)

• Structure: Tooth divided into 6 sextants (two proximal, two buccal, two lingual).
• Scoring: Scores 0-3 in each sextant (0 being the least restorable, 3 the most restorable). Maximum is 18 per tooth.
• Clinical Decision: A tool for evaluating tooth restorability based on the remaining tooth structure (remaining coronal tissue).
• Levels of adequacy: None, inadequate, questionable, and adequate.
• TRI Score: Guide for the clinician in determining if the tooth is suitable for a certain treatment.

Clinical Decision based on TRI Score

• A table based on TRI Score that helps determine the suitability for treatment options.

Revision Advice

• Read lectures, lab sessions and clinical guidelines.
• Use the revision lecture as a guide and pay attention to details.