65 - Esthetic incrustation of the bridge restorations – with acrylic resin or ceramics. Technologies. Types of retention.

section

• retention in orthodontics

• MCR and PFM

• primary and secondary retention

• retention in orthodontics

• Retention is the phase of orthodontic treatment that attempts to keep teeth in the corrected positions after treatment with orthodontic braces.

• Without a phase of retention, there is a tendency for teeth to return to their initial position

MCR AND PFM

primary and secondary retentions

Primary Retention

• Definition:
  Mechanical retention that holds the restoration (e.g., crown, bridge) in place due to its shape and fit.

• How it works:
  It relies on the physical resistance of the tooth preparation—like parallel or slightly tapered walls—to prevent dislodgement.

• Examples:

  • Parallel or slightly converging walls of a tooth prep

  • Friction between the internal surface of the crown and the tooth

Secondary Retention

• Definition:
  Additional features or materials that help strengthen the bond and keep the restoration in place.

• How it works:
  It involves chemical bonding, cementation, or extra mechanical features beyond the basic shape.

• Examples:

  • Use of adhesive or resin cement

  • Micromechanical retention from surface roughness or etching