Telescopic Crown-Bridge Systems

Definition and Characteristics: Comprises a metal coping and attachment system tailored to the prepared tooth. Primary: A metal cap that fits the prepared tooth. Secondary: A cast crown that fits over the metal cap. Metal caps are typically prepared with a thickness of 0.4-0.5 mm. Applications of Telescopic Crown-Bridge Systems:...
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Telescopic Crown-Bridge Systems
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Definition and Characteristics:

  • Comprises a metal coping and attachment system tailored to the prepared tooth.
  • Primary: A metal cap that fits the prepared tooth.
  • Secondary: A cast crown that fits over the metal cap.
  • Metal caps are typically prepared with a thickness of 0.4-0.5 mm.

Applications of Telescopic Crown-Bridge Systems:

  • To alter the shape of a tooth.
  • To increase the crown size of a tooth.
  • For non-parallel abutment teeth and implants.
  • Used in cases with early extraction of lower 6th tooth leading to tipping of adjacent teeth.

Indications:

  • When the bridge abutment teeth are non-parallel and their angulations can’t be corrected by tooth preparation.
  • In malformed and malpositioned teeth.
  • For diastema, protrusion, and increasing vertical dimension.
  • To bring teeth at various occlusal plane levels to the same level.
  • In advanced periodontal cases for splinting.
  • In partial dentures where some teeth will accommodate direct retainers.

Contraindications:

  • Teeth with very short clinical crowns.
  • Teeth with small labio-lingual dimensions.
  • Situations with restrictive vertical space.
  • In severe periodontal diseases.
  • Patients with mental and physical disabilities.

Advantages:

  • The retention force between the inner and outer crowns can be adjusted.
  • Retention remains stable over time.
  • Retention force is generated when the outer crown seats over the inner crown.
  • No harmful stresses on supporting teeth during prosthesis removal.
  • Creates a secondary splinting effect on the supporting teeth.
  • Facilitates hygienic conditions for the periodontium.
  • Protects the supporting teeth from caries.

Disadvantages:

  • Potential for plaque accumulation and undercut areas in the collar region.
  • The outer crown faceting can lead to excessive contour.
  • Excessive tooth material removal for primary and secondary structures can harm the pulp.
  • High cost.
  • Requires precise laboratory work.
  • Long-term use may lead to decreased retention due to wear between the inner and outer structures.

These cover the essential aspects of telescopic crown-bridge systems, including their definition, applications, indications, contraindications, advantages, and disadvantages, highlighting their role in restorative dentistry.

Compatibility Between Telescopic Crowns and Abutments:

  • Frictional retention.
  • Viscosity.
  • Negative air pressure.

Retention and Stability:

  • Pressomatic mechanism.
  • Friction fit system: Rigid and Resilient.

Rigid:

  • Directly transfers chewing forces to the abutment teeth.
  • Distributes chewing loads over a broader alveolar bone surface in the supporting tooth.

Resilient:

  • Primarily transfers vertical forces to the soft tissue.
  • Retention of the telescopic crown can’t always be provided by the wide frictional surface of the telescopic crown on the telescopic cap.
  • In very short clinical crowns or in normal-shaped teeth with material wear, the retention of the telescopic structure may be insufficient.
  • Adding an adjustable retentive component (e.g., a pressomatic or magnetic element) can overcome this problem.

Abutment Tooth Selection:

  • Location, number of abutment teeth in the arch.
  • Amount of alveolar bone.
  • Distance between abutments.
  • Root shape.
  • Opposing dentition.
  • Prosthesis design.

Tooth Preparation and Cap Sizes:

  • Intermediate cuts (vital or devital).
  • Long cuts (vital).
  • Pulp-guided preparation for long caps.
  • Approximately 4 mm of parallel surfaces are needed for adequate retention.
  • Sufficient preparation (risk of overcontour) for upper and lower structures.
  • Attention to cutting depth to provide space for aesthetic material in the vestibule.

Attachment Systems

 Definition and Function:

  • Structures that provide fixation and stabilization of the prosthesis.
  • Comprised of negative and corresponding positive parts.
  • Can be fabricated or semi-fabricated.

Features:

  • Attachment negative space boundary should be 1-1.5 mm above cervical.
  • Depth of 2 mm.
  • Flange length of 4 mm.
  • Flange width should be 0.75 mm.
  • Attachment systems may be contraindicated if the supporting tooth is very short or in a covered bite situation.

Intra-Crown Attachment Systems:

  • Score-BR (frictional).
  • Combi-Snap (frictional and mechanical).
  • Omega-M (frictional).
  • Interlock (frictional).
  • Beyeler (frictional).
  • Score-up (sliding).

Extra-Crown Attachment Systems:

  • SwissLoc NG (mechanical and sliding).
  • Hannes Anchor (mechanical).
  • Lew Passive Attachment (sliding).

Overview:

  • Bridges made with telescopic crown applications meet comprehensive prosthetic requirements such as splinting, stabilization, support, retention, and force dissipation in their designs and plans.

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