RESTO.ppt for education

Defined as any restoration requiring the placement of one or more pins in the dentin to provide adequate resistance and retention forms for tooth with extensive caries or fractures

Used whenever adequate resistance and retention forms cannot be established with slots, locks, or undercuts only.

It has a greater retention than those using boxer or relying solely on bonding system

A. GROSSLY MUTILATED TEETH B. EXTENDED PREPARATIONS

 D. Extensive class V restoration

C. Cores for full coverage restoration

Fine, strong, long term restoration/build-up

Less expensive than a crown

Completed in one appointment

Conservasation of tooth structure

Dentinal microfracture

Microleakage around pin

Perforation of pulp or external tooth structure

Decrease strength of amalgam

Cemented pins/Friction-locked pins/Self-threading pins

rarely used today Pin hole usually large Cemented with

zinc phosphate polycarboxylate

cement LEAST RETENTIVE pin is 0.002 smaller than the

channel 2mm into tooth with

3mm post above tooth

Rarely used Hole in tooth is smaller than cemented Pin is tapped into place MORE RETENTIVE than cemented 3mm into tooth structure & 3mm post above pin is 0.001 larger than the channel

Hole in tooth slightly smaller than pin

Retained by threads on pin More than TWICE AS RETENTIVE as

others 2mm into tooth,

2mm post above pin is 0.001-0.004 larger than the channel

Correct number of pins to place depends upon:

Size of pins Larger diameter ▪ more retention ▪ greater inter-pin distance

*as far as possible 1 pin must be placed for each missing cusp and 1 pin for each missing proximal surface

Within reason, increasing the number of pins increases the retentiveness of the restoration.

With more pins: risk of crazing increases      available dentin decreases strength of the restoration

decreases

At the proximal line angles of molars

At the proximal line angles or cusp tips of premolars

interproximals furcation areas near root concavities (M of mx 1st PM)

in demineralized dentin

At least 0.5mm from DEJ (preferably 1.0mm) in the dentin

If below enamel on tooth, measure 1.0mm from edge of tooth

Pins are made up Pins are made up of of TITANIUMTITANIUM OR OR STAINLESS STEEL STAINLESS STEEL and are and are gold gold platedplated. .

7mm long After placement, the pin is reversed 1/4th turn to reduce stresses on dentin

Pin height can be adjusted appropriately

Available in varying lengths During pin placement when the pin

reaches the bottom of the pin hole, the head automatically shears off, leaving a portion projecting from dentin

It consists of 2 pins connected by means of a joint which serves as a shear line for peripheral pin

Total length is 9mm and 2 pins are about 4mm each

The handpiece need not be reloaded during insertion of more than 1 pin

They have a plastic sleeve that fits into the latch type contra angle handpiece or a special plastic hand wrench

Self shearing Pin engages the dentin and the plastic

sleeve can be discarded Can align well into pin channels

Similar to link series design Self shearing Available as single or 2 in 1 pins The major difference in this pin design is that

pins have sharper threads and a tapered tip to decrease dentinal stresses while seating