Precision attachment

Intracoronal attachments

Extracoronal attachments

Bar type

Frictional

Magnetic: Good retention

Tapered & Parallel walled boxes & tubes

Cantilver

Rigid

Mobile

The rigid could provoke tilting &periodontal destruction, these attachments were developed to allow rotation and resilience within the joints, and therefore reduce the torque over abutment teeth

Resilient

Definition

Semi precision attachments

It includes the largest number of attachments

One part is included within the Crown-root structure

Main role: connecting units or fixed prosthesis or retaining restorations with distal extensions

Studs飾紐

Adjustable metal plates

locks

spring-loaded plungers

Also known as Interlocks

Mainly for joining different sections of fixed prosthesis.

Provide vertical stabilization & support

retangular (box-block): friction can be increased

A slit: in the male part: be widened with a scalpel Blade, increasing retention(Mccollum or Crismani)

Succumb屈於to fatigue & the male (embedded in denture) need replacement

Minimum of 2.5mm of height

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The plunger can be replaced

Require from 4-5mm of height

A spring protrudes a plunger rod that engages to depression in the box

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used for overdenture retention (full denture)

It consist in an stud soldered to a post 螺柱焊接到post上 (cemented in a RCT root) that clips into a flexible ring (embedded in the resin of a denture)

The clip or the stud should be placed once they are no linger resilient

The size of the stud (ball) should meet with the verticle dimension avalaible, so that construction of artificial teeth could be done

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A device which parts lock rapidly together (T-block attachment)

Minimun of 6mm requrired

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recently introduced iron neodymium magnets

Metal keeper attached to tooth

Cobalt-samarium magnets (corrossion)

Ideal for reduced skills

Bad resistance to shear forces (lateral movement)

definition: due to the limitation of size of the intracoronal and the need of movement between the abutment crowns and the removable denture. (more difficult to keep hygiene)

Pin and tube joints or multiple pin-tubes-slots.

Require the use of teeth with strong periodontal support, and should be entirely supported by teeth

Denture becomes a rigid extension of cantilever.

Excellent retention.

Movement only occurs during insertion of denture

inidication

patients with low caries rate

abutments in a food periodontal status, but rampant resorption of the residual ridge

Kennedy class II, with abutments showing good periodontal support&ridge with little resorption

Rotated

Hinges that allow prosthesis to rotate around an horizontal axis transmitting the forces to the residual ridge.

Dalbo attachment is a good example of ball-socket joint

Dalbo stress breaker attachment with an spring within the body of the socket that allows a small amount of verticle setting beside the abutment teeth.

Crismani attachment has also a modification in which and spring is available at the bottom of the box

Require and space of 6mm

Provide good retention & stability, but are difficult to clean(gingival overgrowth)

Bars used to splint roots, crowns or implants are used for retaining either removable bridges, partial dentures and overdentures (mainly)

If indication is not good, may result in weakness of the denture

Depending on the number of abutments/extension will have single sleeve joints or multiple sleeve joints