Resin Bonded Bridges in Dentistry

Resin Bonded Bridges

• Definition: A single pontic supported by a thin metal retainer placed lingually and proximally on the abutment teeth, with minimal preparation limited to enamel and labial surface remaining intact.

Case Selection

• Patient factors to consider:
  • Health and age of the patient
  • Patient expectations
  • Local factors related to dental health and the missing tooth itself
  • Accepting a shortened dental arch in older patients with reduced manual dexterity
  • Preferable to a removable partial denture (RPD) in cases with significant periodontal disease or dental caries
  • Advantageous for young patients who have suffered early loss of an anterior tooth
  • Minimally invasive, requiring minimal clinical time and rarely needing anaesthetic
  • Suitable for patients who are apprehensive of dental treatment or unable to commit to more involved treatment
  • Importance of managing expectations regarding aesthetic outcome and longevity

Abutment Tooth Selection

• Investigations should be carried out to ensure endodontic and periodontal health
• Periodontal support should be assessed considering bone levels and root configuration
• Abutments with active periodontal disease should be avoided
• Coronally, sufficient enamel should be available for bonding
• Surface area may be compromised if teeth are restored or have significant tooth wear
• Alignment or angulation of teeth may affect the degree to which a retainer can be extended
• Unconventional approaches may be necessary in certain cases
• Deciduous teeth can make good abutments due to their multirooted nature and large coronal surface area

Occlusal Features

• Detailed assessment of both static and dynamic occlusal relationships is crucial for optimal success
• Gingival margins and circumferential preparation can be accomplished with a chamfer or round-tipped diamond
• Occlusal rest seats and cingulum notches can be prepared with a diamond or carbide inverted cone bur
• Retentive features (e.g., slots, grooves) can be made with a tapered fissure bur
• Restoration design should be determined before beginning tooth preparation
• Importance of surveying the abutment teeth and making diagnostic preparations on a cast

Preparation and Bonding

• Step-by-step procedure:
  • Leave margins about 1 mm from the incisal or occlusal edge and, if possible, 1 mm from the gingival margin
  • Definite rests and grooves provide resistance form for the retainers and assist in positive seating during cementation
  • Small, defined gingival margins guide the laboratory as to the gingival extent of the retainer
  • Make an accurate impression, as marginal fit is crucial for a resin-bonded restoration
  • Provide temporary occlusal stops to avoid supraocclusion of the abutment teeth

Bonding Materials

• Three different materials to use for RBB:
  • Metal
  • Ceramic
  • Fiber reinforced

Surface Treatment for Bonding

• Depends on retainer material
• Surface treatment for metal RBB:
  • Mechanical: Macro retention
  • Cast perforated resin-bonded bridge (“Rochette bridge”)
  • Water soluble salt crystals (Virginia bridge)
  • Cast mesh pattern (dura lingual)

Pontic Designs

• Extracted natural teeth
• Acrylic teeth
• Bonded to proximal or lingual surface of abutment by wire or meshwork fixed by composite
• Drawback: degradation of composite and loss of pontic
• Composite resin:
  • Restores esthetics and function
  • Nonirritating and hygienic
  • Can be repaired, modified, or removed
  • Fibres can be arranged unidirectionally or bidirectionally to improve mechanical properties

Dealing with Failure

• Biological reasons for failure: caries and periodontal disease
• Technical reasons for failure: debonding
• Importance of oral health education and patient warning regarding debonding