Complex Pin Amalgam Flashcards
When to use pins:
Slots, locks and undercuts aren’t enough for retention
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
Give added support to pins, if needed
Slots, box-like forms, coves, grooves
Advantages of cpa:
Conservative, 1 appt., resistant a and retention ban be increased w pins and slots, inexpensive compared to crown
Disadv of cpa:
Occlusal contact/ anatomy, resistance form difficult to develop than for cusp-only onlay, internal pins can make craze lines in dentin
Ideal preparation design for cpa’s:
None, we use what is left
Tooth preparation for cpa:
90’ cs margin angle in all areas
Reduce cusp in this situation:
F-L extension is more than 2/3 distance from primary groove toward cusp tip
When to use depth cuts:
When the cusp is intact/ normal height
Burs to use for depth cuts on cusps:
556, 169L (side)
Depth of retentive groove for functional and nonfunctional cusps:
2-2.5, min 1.5
Min amal for functional and non functional cusps
2mm, 1.5mm
Sharp internal corners are removed to:
Resistance to fracture from occlusal forces, reduce stress concentration in amal
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
Provide retention for class 1 and2 restos:
Convergence of opposing walls
Vertical retentive grooves should be placed with:
1/4 round, 169L
Vertical retentive groove is aka:
Vertical retentive lock
Bur to use to make the sentinel slots:
330
Where to make slots:
1mm deep and 0.5-1mm inside DEJ
Bur to make coves:
1/4 round bur
Coves are prepared on his plane
Horizontal
Slots and pins are placed in this plane:
Vertical
Slots are placed along:
Gingival floor, axial to DEJ
Which to place first, retentive grooves or pins?
Grooves
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:
1
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
