Classifications of Fixed Partial Dentures and Types Of Removable Partial Dentures

Classifications of Fixed Partial Dentures and Types Of Removable Partial Dentures

Describe the methods used to classify fixed bridges. Add a note on types of retainers used in fixed partial dentures.

Classifications of Fixed Bridges

• Classification depending on edentulous spaces/site
• Classification based on type of connector
• Classification based on type of abutments
• Classification based on retention
• Classification based on materials used
• Classification based on temporary and permanent nature of bridges
• Classification based on span length.

Read And Learn More: Fixed Partial Denture Short Essay Question And Answers

Classification depending on edentulous spaces

Class 1: Posterior edentulous space.

Class 2: Anterior edentulous space.

Class 3: Anterior and posterior edentulous spaces.

Each of these classifications has divisions and subdivisions.

Divisions

To get idea on the type of support.

• Division 1
  • Abutments on one side of the edentulous area are capable of rendering support (Cantilever FPD).
• Division 2
  • Abutments on both sides of the edentulous space are capable of giving support.
• Division 3
  • A single tooth in the center with edentulous space on either side (Pier Abutments).

Sub – divisions

Denote the position of a prospective abutment tooth.

• Sub-division 1: Ideal abutments.
• Sub-division 2: Tilted abutments.
• Subdivision 3: Periodontally-weak abutments.
• Subdivision 4: Extensively damaged coronal structure with good bone support.
• Sub-division 5: Implant abutment.

Groupings

Each of the subdivisions are further grouped into A and B.

Group A: A single abutment on one side of the edentulous space each is sufficient.

Group B: More than one abutment support is required from each side of the edentulous space.

Another classification based on site

• Anterior Bridge — Unilateral (not crossing midline) or bilateral (involves both sides).
• Posterior Bridge — Only in posterior region.
• Complex Bridge — One of terminals beyond canine.

Classification based on type of connector

• Rigid connector.
• Semi-rigid connector.
• Removable fixed partial denture.

Classification based on type of abutments

• Ideal abutment.
• Cantilever abutment.
• Pier abutment.
• Abutment receiving pin support from coronal structure.
• Telescopic crown.
• Endodontically-treated abutment with cast post or post and core support.
• Resin-bonded bridges.

Classification based on retention

Simple and compound.

Simple

Fixed-Fixed—Fixed at both ends.

Fixed-Movable—Nonrigid connector at one terminal (limited movement).

Cantilever—Free end bridge.

Spring cantilever—Pontic at the end of resilient curved arm with support from a distant abutment.

Resin bonded—Presently a single wing is commonly used.

Compound bridge/Hybrid

When more than one type of simple bridges are employed.

Classification based on materials used

Metallic, nonmetallic and combined

Metallic

• Precious (gold alloy)
• Semi precious
• Nonprecious (base-metal alloy).

Nonmetallic

• Resin/Ceramic.

Combined

• Metal with labial/buccal ceramic veneer
• Metal with fullveneer
• Metal-reinforced bridges.

Classification based on temporary and permanent nature of bridges

Provisional

Temporary—After preparation till, a definitive prosthesis is given.

Immediate—Made before extraction and placed immediately after extraction.

Interim prosthesis, splints.

Definitive/Permanent

Fixed partial dentures (single, complex and pier-abutment prosthesis).

Implant abutments.

Classification based on span length

Short span — One missing tooth

Medium span — Two missing tooth

Long span — More than two missing tooth.

Types of Retainers

Complete crowns

• All-metal crowns.
• All-ceramic crowns.
• Metal–ceramic crown.
• Acrylic-fused-to-metal crowns.
• Metal-free (fiber-reinforced composites) crowns.

Partial crowns

Posterior tooth

• Mesial one-half crown.
• Three-quarter crown.
• Modified three-quarter crown.
• Seven-eight crown.

Anterior tooth

• Three-quarter crown.
• Variations of three-quarter crown (Selberg crown).

Complete crowns

All-metal fixed partial dentures

• They are used for replacing maxillary and mandibular posterior teeth
• They also provide proper guide planes for removable partial denture
• Aids in occlusal plane modifications.

Crowns Advantages

• They have the maximum strength and durability
• Less tooth structure is reduced as compared to all porcelain (chamfer margin).

Crowns Disadvantage

• They are not esthetic.

Crowns Indications

• For posterior tooth with short clinical crowns
• For grossly caries or fractured tooth.

Preparation steps

• Occlusal reduction: Using round-end tapered diamond.
• Functional cusp bevel: Round-end tapered diamond.
• Buccal, lingual, axial reduction: Chamfer diamond.
• Proximal reduction: Short thin and chamfer diamond.
• Seating groove: No. 170 bur.

Metals that can be used

Gold

Base-metal alloys.

All ceramic fixed partial dentures

• All ceramic partial dentures are brittle and less fracture resistant compared to all metal partial dentures
• Castable and alumina-reinforced porcelains have more strength compared to conventional porcelains.

Fixed Partial Dentures Advantages

• Can duplicate tooth color exactly
• Good translucency
• Different shades of luting agent give the retainer a natural appearance
• Good as anterior retainers.

Fixed Partial Dentures Disadvantages

• Reduced strength
• Brittle
• More expensive
• Cannot be used on extensively-damaged teeth
• More amount of tooth structure need to be removed compared to other restorations
• Large connectors cause impingement of inter-dental papilla
• Wear of opposing natural teeth
• Two opposing retainers in porcelain can cause a clicking sound
• Not advisable in posterior tooth if heavy loads have to be applied.

Preparation steps

• After placing depth orientation grooves approximately 1.0 mm on labial surface and 2.0 mm deep on incisal half is reduced
• Incisal reduction: 1.5–2.0 mm with flat-end tapered diamond
• Labial and lingual axial reduction: With flat-end tapered diamond
• Lingual reduction: Small wheel diamond
• Axial reduction: Flat-end tapered diamond (aids in retention, resistance and structural durability)
• Shoulder margin: Helps in resistance and marginal integrity.

Types of ceramics

• Conventional platinum matrix ceramics.
• Alumina-reinforced ceramics.
• Slip cast alumina (Inceram).
• Castable ceramics (Dicor).
• Mica glass ceramic (Machinable ceramic: CAD CAM).
• Heat-pressed ceramics: Leucite crystals dispersed ceramics (Optec HSP, IPS empress).
• Resin-bonded ceramics.

Metal–Ceramic fixed partial dentures

This retainer consists of a core of metal with a ceramic external surface.

Two types

• Metal is fused with porcelain on all the surfaces.
• Only the lingual and occlusal surface is of metal, whereas the labial and gingival surface is formed by porcelain.

Fixed Partial Dentures Advantages

• Esthetic and also incorporates the strength of metal
• Characterization can be done by internal and external stains.

Fixed Partial Dentures Disadvantages:

• Not conservative preparation
• For better esthetics, the facial margin needs to be extended subgingivally. This can cause gingival destruction
• Failure at the metal–ceramic junction can occur.

Fixed Partial Dentures Preparation steps:

• For type one with a complete metal and porcelain, preparation is same as for all porcelain
• For type two in which the lingual surface is of metal, a chamfer margin is sufficient, with a shoulder margin on labial aspect to accommodate for the bulk of porcelain.

Acrylic fused to metal

• Poor wear resistance
• Easy to fabricate and adjust
• Esthetically pleasing
• Less expensive.

Fiber-reinforced composite resin bridges

Materials used

Polymer or resin matrices reinforced with glass, polyethylene or carbon fibers. The reinforcing fibers may be unidirectional (long, continuous and parallel), braided or woven.

Classification

• Pre-impregnated with resin (e.g. Fiberkor)
• Impregnation required with fiber (e.g. Ribbond).

Contraindications

• Cannot be used in long-span bridges
• Patients with parafunctional habits
• When opposing tooth is unglazed porcelain.

Advantages

• Optimal esthetics
• Metal free
• Decreased wear of opposing teeth.

Tooth Preparation

• Lingual reduction: Flat end-tapered diamond
• Groove preparation on the palatal surface of the edentulous side
• A shoulder or chamfer margin can be prepared.

Partial crowns

Posterior tooth

• Mesial halves
  • For tilted molar abutments to obtain a parallel path of insertion and to alter the occlusal plane.
• Three quarter crowns
  • Only the lingual aspect is prepared extending till mesiolingual and distolingual transitional line angles
  • Proximal grooves are prepared perpendicular to the prepared surface and the buccal wall is flared with tapered carbide bur
  • In case of additional retention offset is prepared extending from proximal grooves along the buccal cusp.
• Modified three quarter
  • Done on premolars with the preparation extending buccally.
• Seven-eights
  • Includes lingual, occlusal and distal half of buccal surface.

Anterior tooth

Three quarter

Refer to posterior tooth three quarter crown preparation.

Pin ledges

Indications

• When large amount of tooth structure is lost with intact buccal walls
• For restoration and alteration of occlusal surface.

Anterior tooth Contraindications

• In short clinical crowns
• In long-span FPD
• In endodontically treated tooth
• In patients with active caries
• In malaligned abutment tooth.

Anterior tooth Advantages

• Conservation of tooth structure
• Supragingival preparation
• Better visibility of seating and cementation.

Anterior tooth Disadvantages

• Less retentive
• Not esthetic if metal is displayed.