TYPES OF BRIDGES Dr Priyadarshani Pawar A fixed

TYPES OF BRIDGES Dr. Priyadarshani Pawar

A fixed partial denture is defined as “A partial denture that is cemented to natural teeth or roots which furnish the primary support to the prosthesis”also known as bridges. Types of bridges : CONVENTIONAL FIXED PARTIAL DENTURES • • They are the most commonly used type of fixed partial dentures. The design involves fabrication of a fixed partial denture, which takes support from abutments on either side of the edentulous space. • The design may vary according to the condition of the abutments but the abutments on either side should be able to support the fixed partial denture

CANTILEVER FIXED PARTIAL DENTURES • cantilever fixed partial denture is used when support can be obtained only from one side of the edentulous space. • These dentures have compromised support. • The abutment teeth on the supporting side should be strong enough to withstand the additional torsional forces. • Support can be obtained from more than one tooth on the same side of the edentulous space

• Advantages. Very conservative design especially when a single abutment is involved. When secondary abutments are used, parallel preparation can be easily obtained because the abutments are adjacent to one another. Easy to fabricate. • Disadvantages. Produces torquing forces on the abutment. Cannot be used to restore long span edentulous spaces. Minor design errors can affect the abutments in a large scale.

• SPRING CANTILEVER FIXED PARTIAL DENTURES This is a special cantilever bridge exclusively designed for replacing maxillary incisors but these dentures can support only a single pontic. Support is obtained from posterior abutments (usually a single molar or a pair of splinted premolars).

Advantages. Can be used for diastema cases. Metal crown retainers that require minimal tooth preparation, can be used in posterior teeth to replace missing incisors. Disadvantages. The connector bar may interfere with speech and mastication. Deformation of the connector bar may produce coronal displacement of the pontic. There may be food entrapment under the connector bar, which may lead to tissue hyperplasia.

FIXED PARTIAL DENTURES The term denotes fixed partial dentures with rigid connectors. The design of these dentures is more conventional. Since the connectors are rigid, there can be no movement between the connected components. These are the most commonly used fixed partial denture designs

Advantages The major advantages of these partial dentures include: • Easy to fabricate • Economical design • Strong. • Easy to maintain • Robust design provides maximum retention • and strength • Helps to splint mobile abutments • Can be used for long bridges along with periodontally weak abutments.

Disadvantages. Since the connectors are rigid, unwanted stress and lever forces are directly transferred to the abutment producing considerable damage. Requires excessive tooth preparation to achieve a single path of placement. Difficult to cement on multiple abutments. Contraindicated for pier abutments

FIXED MOVABLE PARTIAL DENTURES It is defined as, A fixed partial denture having one or more non-rigid connectors. { GPT } Here, a non rigid connector is used/ fabricated to connect the components of the fixed partial denture. Commonly used non rigid connectors include Tenon Mortis connectors (TMC), loop connectors, split pontic connectors and cross pin and wing connectors

• • • Advantages. They act like stress breakers while transmitting unwanted leverage forces. The abutment is pressurized only during occlusal loading. Improves the health of the abutment. The tooth preparations need not be parallel to one another. Each abutment tooth can be prepared independently according to its requirements. Allows minor movements between the components of the prosthesis. . Parts of the prosthesis can be cemented separately. Disadvantages. Complex design. . Prefabricated connector components are very expensive. Difficult to maintain. Movable parts tend to wear out under constant usage. Cannot be used for long span bridges. Complicated laboratory procedures. Difficult temporisation

FIXED REMOVABLE PARTIAL DENTURESI REMOVABLE BRIDGES One of the major disadvantages of long span fixed partial dentures is that if one abutment fails, the entire prosthesis has to be sacrificed. To overcome this disadvantage, fixed removable bridges were introduced. These dentures cannot be removed by the patient but can be easily removed by the dentist.

MODIFIED FIXED REMOVABLE PARTIAL DENTURES They were developed by Andrew, hence they are also known as Andrew's bridge systems. These dentures are indicated for edentulous ridges with severe vertical deficit. The prosthesis consists of a fixed component and a removable component.

ALL METAL FIXED PARTIAL DENTURES • These dentures are fabricated using only meta. L • Characteristics. • They are indicated for replacing maxillary and mandibular posterior teeth. • They are not aesthetic. • They have the maximum strength and durability. •

METAL-CERAMIC FIXED PARTIAL DENTURES • Here, metal is used to fabricate the core of the prosthesis. The external surface is fabricated using ceramic. The metal is bonded to ceramic chemically, mechanically and ionically. • • Metal ceramic fixed partial dentures can be of two types. In the first type, the metal is surrounded by porcelain on all the surfaces. • In the second type the lingual and occlusal surface is formed by metal and the labial and gingival surface is alone formed by porcelain. These restorations are also termed as porcelain facings or porcelain veneers.

Advantages Aesthetically pleasing. Stronger metal substructure. Characterization possible with use of internal and external stains. Disadvantages. Significant tooth preparation necessary. To achieve better aesthetics, the facial margin of an anterior restoration is often placed subgingivally, this increases the potential for gingival destruction. Brittle fracture can occur due to failure at the metal ceramic junction. More expensive.

ALL CERAMIC FIXED PARTIAL DENTURES All ceramic partial dentures are fabricated using only ceramic. All ceramics are less fracture resistant, hence, they do not render as good retainers. However, alumina reinforced porcelains (inceram) have sufficient strength to be used as good retainers. Advantages. Superior aesthetics. Excellent translucency. Requires slightly more preparation of the facial surface. The appearance can be influenced and modified by selecting different colors of luting agent.

Disadvantages. • Reduced strength due to lack of reinforcement with metal. • It is very difficult to obtain a well finished margin because the ceramic edges tend to chip easily. • These crowns cannot be used on extensively damaged teeth because they cannot support these restorations. • Due to porcelain's brittle nature, large connectors have to be used, which usually leads to impingement of the inter dental papilla. This increases the potential for periodontal disease. . • Wear of opposing natural teeth. •

ALL ACRYLIC FIXED PARTIAL DENTURES Characteristics. Only indicated for long term temporary or interim prostheses. Can be used for making fixed periodontal splints. Poor wear resistance. Easy to fabricate and adjust. Aesthetically pleasing.

VENEERS Veneer is a layer of restoration placed over the labial surface of a tooth. They are primarily used as aesthetic adjuncts to discolored or fractured teeth. Type of Veneers Ceramic It is the most ideal veneering material when used with metal substructure or in all ceramic restorations. Acrylic Tooth colored acrylic can be used with metallic restorations as a veneer. They are not considered as a permanent material due to poor wear resistance. Recent advances include use of indirect composite resins as veneer materials.

SHORT SPAN BRIDGES These are simple fixed partial dentures, which replace one or two teeth, and the teeth on either side are ideal abutments. These dentures are considered ideal because they have minimal torquing forces. For example replacement. First molar

LONG SPAN BRIDGES Long span bridge denotes a condition where two or more teeth have to be replaced and more than one abutment has to be taken for support on either side. Long span bridges have the potential for producing more torquing forces on the bridge and the weaker abutment. (especially weak abutments are adversely affected) PERMANENT OR DEFINITIVE PROSTHESIS This term denotes all conventional fixed partial dentures inserted as definitive or final treatment. Most fixed partial dentures made of metal ceramic, all metal or all ceramic are considered permanent restorations. They are placed at the final phase of a rehabilitative procedure.

LONGTERM TEMPORARY BRIDGES These dentures are usually made of acrylic resin. They are designed to be used for a few weeks to months. Indications: These restorations may be given for the following conditions: During the interim period of treatment when the patient is undergoing extensive occlusal rehabilitation. (E. g. Intruding a supra erupted tooth). . In patients undergoing periodontal therapy these restorations may be inserted to act as splints.

FIBRE REINFORCED COMPOSITE RESIN BRIDGES These are basically bridges, which are reinforced by a bar of glass fibers over which indirect posterior composites are built. Classification Fibre reinforced composites can be classified into: Pre impregnated (e. g. Fibrekor, Splint it): The manufacturer impregnates them with the resin. Impregnation required (e. g. Ribbond, Cpost): fibre impregnation has to be done by the dentist. Contra indications It cannot be used when fluid control is not possible. Cannot be used for long span bridges It should be avoided in patients with para functional habits It should not be used opposing unglazed porcelain teeth.

RESIN-BONDED FIXED PARTIAL DENTURES As the name implies, these are fixed partial dentures, which are cemented onto the abutments using special resins. Basically these dentures consist of one or more pontics supported by thin metal retainers placed only on the lingual and/ or proximal surface of the abutments. Retention in these prostheses relies on the adhesive bonding between etched enamel and the metal casting (retainer). Indications. • Retainers for fixed partial dentures for abutments with sufficient enamel to etch for retention. • Splinting of periodontally compromised teeth. . dentitions after orthodontics • Medically compromised, indigent and adolescent patients who cannot co operate with long sessions of therapy. • Prolonged placement of interim prosthesis to surgical procedures. Stabilizing augment

• • • Contraindications. Patients with an acknowledged sensitivity to base metal alloys. When the facial esthetics of abutments require improvement. Insufficient occlusal clearance to provide 2 to 3 mm vertical frictional retention in the axial walls. E. g. abraded teeth. Deep vertical overbite. Inadequate enamel surfaces to bond. E. g. extensive caries, existing restorations. Incisors with extremely thin facio lingual dimensions. Advantages. Non invasive to dentin with lingual andproximal tooth preparation including occlusal rests. Decreased pulpal irritation. Conservative with undeniable patient appeal/comfort. . Decreased tissue irritation due to the placement of supragingival margins. Does not require cast alterations or removable die preparation. Reduced cost with less chair time.

Disadvantages. – Criteria for choosing the patient are not discrete. Demanding technique and tooth preparation. – Even minor laboratory errors cannot be corrected easily. Plaque accumulation may occur because design is outside the dimensions of the natural tooth. – Bulky contours may be intolerable in some patients. . Patient expectations of esthetics are high. – Not ideal for replacing more than one tooth. – Graying of the incisal surfaces Types of Resin Bonded Fixed Partial Dentures Resin bonded fixed partial dentures can be classified as: . Rochette bridge, Maryland bridge, Cast mesh fixed partial dentures, Virginia bridge.