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Prosthodontic Fundamentals

Principles and Procedures of Dental Prostheses

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Course Objectives

By the end of this module, you will understand:

Classification of prosthodontic treatments
Complete denture fundamentals
Removable partial denture design
Fixed prosthodontic principles
Dental implant systems
Occlusal concepts
Impression techniques
Prosthodontic materials

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Prosthodontic Classification

Fixed Prosthodontics

Crowns:
- Full coverage
- Onlays/overlays
Fixed Dental Prostheses:
- Conventional FDP
- Cantilever FDP
- Maryland bridge
Materials:
- Metal-ceramic
- All-ceramic
- Zirconia

Removable Prosthodontics

Complete Dentures:
- Conventional
- Immediate
- Overdentures
Partial Dentures:
- Cast metal framework
- Acrylic resin
- Flexible
Materials:
- Heat-cured acrylic
- Cobalt-chromium
- Nylon polymers

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Complete Denture Fundamentals

Anatomical Landmarks

Maxillary:
- Incisive papilla
- Rugae
- Vibrating line
- Hamular notch
Mandibular:
- Retromolar pad
- Buccal shelf
- Mylohyoid ridge

Border Molding

Define peripheral seal
Green stick compound
Muscle trimming

Complete Denture

Denture Teeth Selection

Anterior:
- Size (interpupillary width)
- Shape (face form)
- Color (skin tone, age)
Posterior:
- Anatomic vs non-anatomic
- 0° vs 20° vs 33° teeth

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Complete Denture Fabrication

Clinical Steps

Primary impression (alginate)
Custom tray fabrication
Border molding
Final impression (zinc oxide eugenol)
Jaw relation records
Teeth try-in
Denture insertion
Post-insertion adjustments

Denture Fabrication

Laboratory Steps

Cast pouring
Baseplate fabrication
Wax rim contouring
Teeth arrangement
Flasking
Dewaxing
Packing
Curing
Finishing/polishing

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Removable Partial Denture Design

Components

Major connector:
- Palatal strap/bar
- Lingual bar
Minor connector
Rests:
- Occlusal
- Cingulum
- Incisal
Clasps:
- Circumferential
- Bar (RPI, RPA)

Design Principles

Kennedy Classification:
- Class I: Bilateral edentulous
- Class II: Unilateral edentulous
- Class III: Unilateral bounded
- Class IV: Anterior bounded
Surveying:
- Determine path of insertion
- Identify undercuts

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Fixed Prosthodontics

Tooth Preparation

Principles:
- Preservation of tooth structure
- Retention and resistance
- Marginal integrity
Margins:
- Chamfer
- Shoulder
- Knife-edge
Taper:
- 6° total convergence
- Parallel walls

Provisional Restoration

Functions:
- Protect prepared tooth
- Maintain occlusion
- Preserve gingival health
- Esthetics
Materials:
- Acrylic resin
- Bis-acryl

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Impression Techniques

Complete Denture

Preliminary:
- Alginate in stock tray
Final:
- ZOE paste in custom tray
- Border molded first

Fixed Prosthodontics

Dual-phase technique:
- Heavy-body + light-body
Materials:
- Polyvinyl siloxane
- Polyether

Dental Impression

Digital Impressions

Advantages:
- No material distortion
- Immediate evaluation
- Patient comfort
Systems:
- CEREC Omnicam
- 3M True Definition
- iTero

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Dental Implant Systems

Implant Components

Fixture:
- Osseointegrated
- Ti or ZrO₂
Abutment:
- Stock/custom
- Ti, gold, ZrO₂
Prosthesis:
- Crown
- Bridge
- Overdenture

Surface Treatments

Machined
Acid-etched
HA-coated
SLActive

Implant Components

Treatment Planning

Bone assessment:
- CBCT analysis
- Bone density (Lekholm & Zarb)
Prosthetic options:
- Single tooth
- Implant bridge
- All-on-4/All-on-6
Loading protocols:
- Immediate (48h)
- Early (2-6w)
- Conventional (3-6m)

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Occlusal Concepts

Complete Denture Occlusion

Balanced occlusion:
- Bilateral contacts
- Protrusive/working balance
Neutrocentric concept:
- Flat plane
- Neutral position
Lingualized occlusion:
- Max lingual cusps contact
- Reduced lateral forces

Occlusal Schemes

Fixed Prosthodontics Occlusion

Mutually protected:
- Canine guidance
- Posterior disclusion
Group function:
- Multiple contacts
- For compromised canines
Centric relation:
- Reproducible position
- Basis for reconstruction

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Prosthodontic Materials

Polymers

PMMA:
- Denture bases
- Heat-cured/autopolymerizing
Elastomers:
- Soft liners
- Silicone/polyacrylate
Composites:
- Provisional restorations
- Repairs

Dental Materials

Metals & Ceramics

Alloys:
- Cobalt-chromium (RPDs)
- Gold alloys (crowns)
- Titanium (implants)
Ceramics:
- Feldspathic (veneers)
- Lithium disilicate (crowns)
- Zirconia (bridges)

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Troubleshooting Prostheses

Complete Dentures

Sore spots:
- Selective pressure areas
- Relieve with bur
Loose fit:
- Reline/rebase
- Denture adhesives
Fractures:
- Midline fractures
- Repair with acrylic

Denture Problems

Fixed Prostheses

Debonding:
- Improper preparation
- Cementation failure
Fractured porcelain:
- Repair with composite
- Replace restoration
Recurrent caries:
- Marginal leakage
- New restoration needed

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Digital Prosthodontics

CAD/CAM Systems

Workflow:
- Scan → Design → Mill
Materials:
- Zirconia
- PMMA
- Wax
Advantages:
- Precision
- Efficiency
- Reproducibility

3D Printing

Applications:
- Surgical guides
- Models
- Temporary crowns
- RPD frameworks
Technologies:
- Stereolithography (SLA)
- Digital light processing (DLP)
- Selective laser sintering (SLS)

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Prosthesis Maintenance

Removable Prostheses

Daily care:
- Brushing with soft brush
- Denture cleansers
- Overnight soaking
Professional care:
- Annual examinations
- Relines as needed
- Oral cancer screening

Fixed Prostheses

Home care:
- Floss threaders
- Interproximal brushes
- Non-abrasive toothpaste
Professional care:
- Marginal integrity checks
- Occlusal evaluation
- Radiographic monitoring

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Key Takeaways

Proper diagnosis and treatment planning are essential
Biomechanical principles guide prosthesis design
Material selection impacts longevity
Occlusal harmony prevents complications
Digital workflows are transforming prosthodontics
Maintenance ensures long-term success
Patient education improves compliance

Questions and Discussion

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