Lecture #6 Flashcards Preview

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Flashcards in Lecture #6 Deck (21)
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1
Q

Complex Amalgam Restoration (PART 2)

Resistance/Retention (cont’d)

A

Pins,
Slots,
Peripheral Shelf,
Endodontically-Treated Teeth

2
Q

Pins - Indications/advantages

A

o Extensive loss of tooth structure/coronal dentin (need retention)
o Sufficient O-G height (4 mm)
o Quicker/less expensive/more conservative than crown

3
Q

Pins - Disadvantages

A
o Risk of pulpal/periodontal perforation
o Stresses tooth – crazing/cracking
o Extra equipment needed
o Difficult to adequately condense amalgam
o Weakens amalgum
4
Q

Types of Pins

A

o Cemented, friction-locked, threaded (most common)
o Thread Mate System (TMS) – threaded, each size of pin has drill
▪ 4 Sizes: minuta, minikin, minim, regular (smaller =
less stress)
▪ Pin hole slightly smaller diameter than pin
o Max Pin – has shoulder stop

5
Q

Pins - Placement

A

o Place 1 mm​ inside DEJ
o Allow space for small condenser all around (use cove ​prep)
o Within confines of future crown prep, on flat​ surface
o Place starter hole w/ 1⁄2 mm round bur (guide for drill)
o Drill 1 mm at a time (to 2 mm), keep drill straight, parallel ext. surface, 90° to
pulpal floor
o Place pin w/ slow speed, ccw direction​, self-limiting depth (2 mm)
o Rule of 2’s: 2 mm of pin in dentin, 2 mm in amalgam, 2 mm bulk above

6
Q

Pins - Place in line angles (corners) of tooth

A

o 1 pin per missing line angle
o Danger spaces: middle, mesial concavity of max. 1st
premolar, bifurcation of 1st/2nd molars

7
Q

Pins - Interpin distance (>2 increases stress) – 3 mm for minikin, 5 mm for minim/regular

A

:) You’ve got this!!!

8
Q

Pins - May need to bend pin to w/in restoration outline

A

Yay!!!

9
Q

Pins - Cutting pins:

A

use high speed, #169 bur, come from side, brief contacts

10
Q

Pins - Horizontal pins IDICATIONS

A

not need cusp reduction (keep facial cusp = esthetic)

11
Q

Pins - Horizontal pins PREPARATION: same guidelines as vertical

A

▪ increases mechanical advantage if near occlusal surface

▪ minim/minikin pins only

12
Q

Slots INDICATIONS

A

o minimum O-G height with horizontal bulk of dentin
o no extra equipment needed
o rapid to place
o less chance of pulpal/periodontal perforation
o does not stress dentin or weaken amalgam/tooth

13
Q

Slots DISADVANTAGES (same as amalgapin)

A

o may fracture if matrix is moved (not stable) or removed too early
o risk of voids from inadequate condensation
o need more dentin thickness
o decreased tensile strength

14
Q

Slots PREPERATION

A

o use inverted cone bur to full depth, then follow DEJ around tooth (retentive b/c channel is wider at the bottom)

15
Q

***Amalgapins -

A

vertical bulk / Slot – horizontal bulk

16
Q

Peripheral Shelf INDICATIONS/ADVANTAGES

A

o need additional resistance
o allows conservative prep if enamel lost w/o dentin or cervical
decalcification/restoration present
o no extra equipment needed
o does not stress dentin or weaken amalgam/tooth

17
Q

Peripheral Shelf DISADVANTAGES

A

o unidirectional resistance only
o risk of voids from inadequate condensation
o time-consuming
o more external restoration/amalgam display
o no advantage over amalgapin/slot

18
Q

Peripheral Shelf PREPERATION

A

use # 58 bur to guide 1.5 mm wide/deep shelf

19
Q

Endodontically-Treated Teeth

A

Pulp chamber provides great retention

20
Q

Amalgum bonding –

A

in addition to mechanical retention; must condense into amalgam well

21
Q

Matrix

A

▪ Many types: Tofflemire, Automatrix, etc.

▪ Stabilize w/ wedges, bite registration, modeling compound