The basic concept of modern restorative and reconstructive dentistry is to protect the remaining sound tooth tissue.

When missing tooth structure or teeth are replaced, minimal biologic risk should be involved to reestablish function and esthetics. To proven reliability and durability of complete-crown metal ceramics made them the method of choice for posterior singletooth restorations and fixed partial denture (FPD). However, this restoration required considerable reduction of tooth structure.

The increased use of the adhesive technique and preservation of dental tissues have greatly impacted conservative tooth preparation design. The development of fibre-reinforced composite (FRC) technology and all-ceramic systems has opened the potential for fabrication of metalfree restorations with durability and good aesthetics.

The reduced invasiveness of these resin-bonded FPD´s makes them appealing alternative to conventional preparations. This advantage emphasizes in cases where the residual dentition exhibits low caries activity.

Dentapreg™ Bridge thanks to its outstanding mechanical properties and variety of shapes and fiber architecture allows to follow a minimum invasivity principle: the preparation for bridge retention will exclusively be determined by the shape and size of previous cavity.

Terminology Used in Bridgework

• FPD = Fixed Partial Denture, bridge
• Abutment = tooth to which a bridge or partial denture is attached
• Framework = structure connecting to abutments in order to carry pontic
• Retainer = part of the bridge framework which fit the restoration (crown, inlay) of abutment and is connected with this restoration
• Pontic = artificial tooth as a part of a bridge
• Connector = part of the bridge framework attaching pontic to retainer. Connectors can be rigid or norigid (male-female-locking arrangements)
• Span = space between natural teeth that is to be filled by the bridge
• Saddle = is the area of the edentulous ridge over which the pontic will lie
• Pier = abutment tooth supporting two pontics, each pontic being attached to a further abutment tooth
• Unit = when applied to bridgework, means either retainer or a pontic. A bridge with two retainers and one pontic would therefore be a three-unit bridge
• Member = when applied to bridgework, means replaced tooth. A bridge replacing two teeth would therefore be a two-member bridge
• Substructure = bundle of reinforcement fibers
• Suprastructure = structure creating anatomical shape and contour of pontic over the bridge framework
• Slot/Box = rectangle hollow of the hubic shape in the distal or mesial side of the teeth, no shoulders
• Groove = long shallow semicircular channel which lies on the oral side on the tooth; used mostly for incisors
• Inlay = restoration, which lies inside the cusp tips of a tooth (MO: mesio-occlusal, MOD: mesio-occlusal distal) – intraconal restoration
• Onlay = more extensive restoration that cover one or more cusps of a tooth, clasiffied as smallest extracoronal restoration
• Complete crown = restoration covering the entire anatomy of a tooth´s clinical crown
• Partial crown = restoration covering more than half but not all of the tooth´s clinical crown. A partial crown is named according to the fractional amount of the clinical crown it covers (three-quarters, four-fifth, seven-eights)

Types of Bridge Retainers

• Complete crown
• Partial crown
• Onlay
• Inlay
• Groove
• Slot
• Non invasive/extracoronal – wings
• Non invasive/extracoronal – splint (Rochette´s splint)
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Biomechanics of the Bridge Framework

Primary roles of bridge framework are:

• To carry the pontic
• To shift the load applied to pontic during mastcation to abutment teeth.
  

The major portion of masticatory forces shifted by bridgework from pontic to abutment teeth acts verticaly. Therefore the bridgework is subjected to deflection. It creates compression in upper part of the structure and tension in lower part of structure. This type of stress requires to put substructure (Dentapreg™ Bridge strip) in the bottom part of bridge framework. There are also peeks of shear stress in the interproximal area between abutment teeth and pontic. In order to minimize these peeks it is recommended to form a small curvature with Dentapreg™ strip.

Typology of Bridges Made from Dentapreg^TM

• Complete crown
• Partial crown
  

Intracoronal retentions with reduced invasivity

• Onlay
• Inlay
• Slot
  

Extracoronal non invasive retentions

• Wing
• Splint (Rochette´s Bridge)

Symetry of Retentions

• Bridge with one type of retention (uniform retention)
• Bridge with two types of retention (combined retention)

Durability

• Permanent bridges
• Semipermanent bridges
• Provisional bridges