Complex Pin Amalgam Flashcards by Tedman McMahon

When to use pins:

Slots, locks and undercuts aren’t enough for retention

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Indications for cpa:

One or more cusps need capping, definitive final restoration, foundation resto, control resto in teeth that have a questionable pulpal and pd px, control resto in teeth w a uterus or sever caries

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Give added support to pins, if needed

Slots, box-like forms, coves, grooves

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Advantages of cpa:

Conservative, 1 appt., resistant a and retention ban be increased w pins and slots, inexpensive compared to crown

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Disadv of cpa:

Occlusal contact/ anatomy, resistance form difficult to develop than for cusp-only onlay, internal pins can make craze lines in dentin

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Ideal preparation design for cpa’s:

None, we use what is left

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Tooth preparation for cpa:

90’ cs margin angle in all areas

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Reduce cusp in this situation:

F-L extension is more than 2/3 distance from primary groove toward cusp tip

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When to use depth cuts:

When the cusp is intact/ normal height

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Burs to use for depth cuts on cusps:

556, 169L (side)

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Depth of retentive groove for functional and nonfunctional cusps:

2-2.5, min 1.5

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Min amal for functional and non functional cusps

2mm, 1.5mm

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Sharp internal corners are removed to:

Resistance to fracture from occlusal forces, reduce stress concentration in amal

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Cusp reduction should extend to here:

Just past F/L groove, vertical wall against the adjacent in reduced cusp, try to have 2 opposing walls that converge, if possible

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Provide retention for class 1 and2 restos:

Convergence of opposing walls

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Vertical retentive grooves should be placed with:

1/4 round, 169L

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Vertical retentive groove is aka:

Vertical retentive lock

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Bur to use to make the sentinel slots:

330

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Where to make slots:

1mm deep and 0.5-1mm inside DEJ

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Bur to make coves:

1/4 round bur

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Coves are prepared on his plane

Horizontal

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Slots and pins are placed in this plane:

Vertical

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Slots are placed along:

Gingival floor, axial to DEJ

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Which to place first, retentive grooves or pins?

Grooves

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Types of pins:

Cemented, friction locked (undersized channels), self threaded

How to place friction locked pin:

Mallet into undersized channel

Pin types, shortest to longest:

Self-threading, cemented, friction-locked

Cemented pins:

Miles Markley, 1958, stainless steel, threads or serrations, less internal stress, least retentive, rarely used, 0.025 pin in 0.027 hole in dentin, 3-4mm hole depth, 2mm projects above hole, zinc phosphate cement

Instrument to push cement into pin holes:

Lentulo spiral instrument

Cut pin w:

Wire cutting pliers

When to use rotating carborundum disc on pin:

To round end

How to bend pin:

2 pairs of pliers

Friction locked:

Goldstein, 1966, 0.022 inch (typo?) tapped into 0.021 inch hole, takes advantage of elasticity of dentin, 2-3mm depth, 3mm above hole pin, 2-3 X more retentive than cemented, more internal stress than cemented

Most used pin system:

Self threading

Self threading pin system:

1966, Going, diameter: 0.0015-0.004in smaller than diameter of pin, dentin elasticity permits insertion, depth: 2mm, 2mm above hole, 3-6 X more retentive than cemented, dentinal stress during insertion causing craze lines

TMS

Thread mate systems, most widely used, many sizes, color coded, great retention, (pin, wrench, drill in set), gold plated stainless steel or titanium

Types of hand wrenches:

Metallic or plastic

4 sizes and diameters of TMS pins:

Regular: gold, minim: silver, minikin: red, minuta: pink (largest to smallest)

2 types of twist drills:

Depth limiting 2mm, standard 5mm

2 factors in choosing pin:

Amount of dentin, amount of retention desired

For posterior teeth:

Minikin pins (0.019), reduce dentinal crazing, pulpal penetration, and potential penetration, minim back up if hole is over prepared

Minuta:

Least retention. Can't use for posterior teeth

The larger the pin,

The greater the retention

5 designs of TMS pins:

Standard, self-shearing, 2-in-1, link series, link plus

Standard:

Self-shearing:

Top portion shears off once the bottom is hit, plastic sleeve discarded

2 in 1:

Shears in half, one half in handpiece, can place in another pinhole, each is shorter than standard pin

Link series:

Available in all sizes,

Link plus

Shorter stalk at 2mm, single and 2 in 1 design, 2.7mm length extends out of dentin, self shearing, color coded, plastic sleeve

Minuta hand wrench shank:

Not straight

Minim wrench:

Banded

Non banded wrench:

Regular and minikin

Standard can only be used w, all others an be used w:

Hand wrench, latch type contrangle w approp chuck

Hand wrenches must use:

Dental tape/ floss around upper portion

If rubber dam can't be used with patient, what should you do?

Cotton gauze to shield throat

Location for pin placement:

Need 2mm amal, 1mm sound dentin around pin channel, 0.5-1m from DEJ or 1-1.5mm from external surface of tooth, whichever is greater

Pin channel placement:

Parallel to external tooth surface, perpendicular to direction of pin channel, prevents perforation

Lager pins:

Greater retention, rarely used, create crazing/ cracking, risk of exposing pulp chamber

Can pins be placed directly next to walls?

No, need access to condense amalgam around pin

What to do if there is not adequate space to condense around a pin?

Create a cove around the pin, 169L or 245 bur

Purpose of pilot hole

Accurate pin placement/ twist drill placement, prevent crawling if drill during rotation

Bur to make pilot hole:

1/4 round

What can we use to insert the depth limiting twist drill

Plastic hand piece or slow speed

Why we add slow gear onto slow speed for pin placement

Increases torque, tactic sense, reduces risk of stripping threads in dentin when pin is in place

Drill system we are using:

Link plus system

Speed for pin placement of drill

Very low speed

How many hand movements for pin placement

2 max, don't angle either, should always vessels rotating

Pins should not be bent for these reasons:

To make parallel with other pins, to increase pin retention

When to bend pin

To allow condensation, with pin bender tool, firm, even pressure

Why not to use black spoon excavator to bend pin

Risk of slipping, less control while bending, bend pin at orifice, increases risk of crazing/ cracking dentin, cracking pin, pin bending tool places fulcrum of bend above the point of insertion into dentin

How to close open space of Tofflemire system when doing large prep:

Insert cut piece of matrix band between band and adjacent tooth

Alternate system to create proper contour of large resto:

Auto matrix system, 360' coverage

How to shorten pins after placement

1/4 round bur