Accessory Retention

Question 1

_____ ______ is often used with large restorations
◦ Especially amalgam
◦ Amalgam relies completely on mechanical
retention

Answer 1

Accessory Retention

Question 2

____ ____ does NOT seal or
increase strength!
◦ NO effect on resistance form

Answer 2

Accessory retention

Question 3

_____ _____ is used To improve retention

◦ when more conservative methods can’t be used

Answer 3

Pin placement

Question 4

t/f Pins are typically seen in extensive preps that often have a missing cusp.

Answer 4

true

Question 5

The following are contraindications or indications for pin placement?

Severe loss of tooth structure Endodontically treated teeth Large pulp canals Difficult access Tooth already serves as abutment for partial denture

Answer 5

Contraindications

Question 6

Economical ◦ 70% of four surface amalgams are successful at 5 years compared
to gold crowns (84% success) (Martin & Bader, 1997) ◦ 72% of amalgam restorations survive for 15 years including those
with cuspal coverage (Smales, 1991) One appointment Alternative to extraction Pins remove minimal tooth structure compared to other methods ◦ less than slots, grooves and amalgapins

Answer 6

Advantages of pin placement

Question 7

Introduces stresses in the dentin which can lead to crazing and even fracture

The pin does not strengthen the amalgam
◦ its only function is to provide additional retention and or resistance.
◦ Pins reduce the compressive and transverse strength
of amalgam

Possibility for perforation- Into pulp or into periodontal ligament

Pin Microleakage around pin Perforation
Anatomy harder to carve

Answer 7

Disadvantages of Pin placement

Question 8

t/f: Do not use pins in non-vital teeth

Answer 8

true

Question 9

Why do we not use pins in non-vital or endo treated teeth?

Answer 9

◦ endodontically treated teeth are brittle
◦ Pins can concentrate stress
◦ Lead to fracture

Question 10

the following are alternatives to ___ _____:

Amalgam Core
◦ Retention from pulp chamber Post Retained Amalgams
◦ Post placed in actual canal, not dentin

Answer 10

Pin placement alternatives

Question 11

Where is the pin always placed?

Answer 11

dentin

Question 12

What are the three types of pins used?

Answer 12

Cemented
Friction Lock
Self-Threading

Question 13

Which type of pin is used at UMKC

Answer 13

self threading

Question 14

◦ Pin hole larger than pin (0.001 - 0.002” larger than pin) ◦ Cemented with zinc phosphate cement ◦ Pin must be 3-4mm in length for adequate retention ◦ Least retentive of available pins

Answer 14

Cemented

Question 15

What type of pin is this?
◦ Pin hole is 0.001” smaller than the pin ◦ Pin is tapped to place - resiliency of dentine
retains pin ◦ 2-4mm long pin hole ◦ 2-3 times as retentive as cemented pins ◦ Dentin exhibits signs of stress

Answer 15

Friction lock

Question 16

What kind of pin is this?
Pin hole is 0.002” smaller than pin Pins self threads into dentin

Use hand wrench or Latch grip on slow speed

5-6 times as retentive as the cemented pin

High crestal and apical stresses; Crazing and microleakage

Greater stresses in dentin
There should be at least 1.0 mm dentin around pin hole

USED AT UMKC

Answer 16

self threading

Question 17

Do multiple pins increase retention?

Answer 17

yes

Question 18

disadvantages of multiple pins?

Answer 18

◦ Increases dentin crazing ◦ Amount of available dentin between pins
is decreased ◦ Strength of amalgam restoration is
decreased ◦ More difficult to condense around the
pins

Question 19

t/f: Pins should be placed 5mm apart from each other • MINIMUM of 3 mm apart

Answer 19

true

Question 20

t/f: Pins should be 1mm from wall of prep • MINIMUM 0.5mm from wall

Answer 20

true

Question 21

t’f: Pin should be 2mm deep into the dentin

Answer 21

true

Question 22

t/f: Self-threading pins: 72.6 lbs of retention at 2 mm in the dentin.

Answer 22

true

Question 23

Which type of pin is Type of pin: most common 99% used, and most retentive

Answer 23

self threading

Question 24

T/f: Orientation of Pins: align pins vertically along long access of tooth
◦ If using multiple pins, slightly angle in different directions
◦ Avoid bending, if possible

Answer 24

true

Question 25

t/f: ◦ increasing the number of pins increases retention up to a certain point.
◦ Too many pins reduces the strength of dentin and the restoration and may
cause dentinal fractures

Answer 25

true

Question 26

What did the dentist say when Tiger Woods came in for an appointment?

Answer 26

You have a hole in one.

Question 27

t/f: increased diameter= increased retention

Answer 27

true

Question 28

If pins breaks, place another one __ mm away from broken pin

Answer 28

1.5

Question 29

What pin size is this?
◦ Most frequently used threaded pin ◦ Start with a 0.021 and if you strip the hole, place a
0.027 pin

Answer 29

Minim 0.021

Question 30

t/f: Use one pin per missing cusp, axial wall, or line angle. Use no more than 4 pins/tooth

Answer 30

true

Question 31

t/f: Place the pin in line angles

◦ Greatest area of bulk

Answer 31

true

Question 32

What sites should be avoided for pulp exposures

Answer 32

◦ Mesio facial corner of Max and Mand 1st molar
◦ Distal mand molars and max lingual of molars ◦ Mid-facial, mid-mesial and mid-distal furcations of Max 1st & 2nd
molars

Question 33

Concavities to watch for

Answer 33

Mesial concavity over Max 1st PM

Mid-lingual and mid-facial of Mand 1st and 2nd molars

Mid-facial, mid-mesial and mid-distal furcations of Max 1st & 2nd molars

Question 34

t/f: it is important to drill pin hole on a flat prepped area.

Answer 34

true

Question 35

t/f:
Place pin minimum of 0.5 mm inside DEJ
◦ Preferably 1.0mm inside DEJ

Answer 35

true

Question 36

When placing a crown….
_-__ mm inside DEJ
◦ Want to avoid exposing the pin
during future crown preparation

Answer 36

1.0-1.5

Question 37

t/f: Pins should be a minimum of 0.5 mm from any wall to allow room for condenser and condensation of amalgam around the pin

Answer 37

so very true

Question 38

t/f: There must be 2mm of amalgam over the top of the pin, otherwise the amalgam may fracture

Answer 38

true

Question 39

If pin is too tall, you can do what two things?

Answer 39

reduce height with handpiece or bend slightly (avoid bending if possible)

Question 40

What process is this?
Stabilize the pin with a forceps and cut away the excess with a bur
Cut perpendicular to pin
◦ if you cut parallel to pin the pin will unscrew and
become loose.

Check to see if the pin is loose.

Answer 40

Cutting the Pin

Question 41

t/F: Do not use a condenser or any other instrument to push on the pin and flatten it.
◦ Bending the pin with a condenser will further concentrate
stresses in the crestal region of dentine.

Answer 41

true, but I definitely did this on my prep.

Question 42

t/f: always use a rubber dam with pin placement.

Answer 42

true otherwise could aspirate.

Question 43

t/f: pulpal perforation is preferable to a periodontal ligament perforation

Answer 43

true

Question 44

What kind of perforation?
◦ usually results in an abscess
◦ treated by uncovering the perforation, removing the part of the pin that
extend through and/or plugging this area with amalgam ◦ less predictable prognosis.

Answer 44

periodontal perforation

Question 45

What type of accessory retention is this?

◦ Similar to grooves, but larger
◦ created with 33 1/2 inverted cone bur
◦ 0.5-1.0 mm wide and 1mm deep
◦ should be undercut slightly to provide retention

Answer 45

slot

Question 46

What type of accessory retention?
• allow for restorative material to act as “pin” • more tooth structure is removed • BUT slots result in fewer microfractures compared to pins

Answer 46

locks

Question 47

What kind of accessory retention?
- Utilize #245 bur - Drill hole 1mm wide,
2mm deep -Condense amalgam into pin hole

Answer 47

amalgam pin

Question 48

All of the following are benefits for using (composite or amalgam) for build up material under crown?

oCan visualize when preparing crown
oEase of manipulation
oGood mechanical properties oNot as technique sensitive as composite resin
oGood dimensional stability oGood wear resistance oRelatively inexpensive

Answer 48

Amalgam benefits:

Question 49

t/f: Place slots, locks, grooves before placing pinhole

Answer 49

true