This document discusses complex amalgam restorations, which replace missing tooth structure from fractures, caries, or existing restorations. They require additional retention methods like pins or slots. Pin-retained and slot-retained amalgam restorations are described in detail, including tooth preparation techniques, pin selection and placement, and potential problems. Amalgam foundations are also briefly covered. The document provides information on indications, advantages, disadvantages, and clinical techniques for complex amalgam restorations.

1. COMPLEX AMALGAM
RESTORATION
Dr. Basavan Gowda
Reader
Dept.of Conservative Dentistry&Endodontics
Navodaya Dental College
Raichur

2. DEFINITION
• Restorations that are used to replace
• any missing structure of teeth that have fractured,
• have severe caries involvement,
• or have existing restorative material.
• These restorations usually involve the replacement of one or more
missing cusps
• and require additional means of retention e.g. Pins, Slots, Locks

3. QUALITY OF AMALGAM
• Easy to use
• High compressive strength
• Wear resistance
• Long term performance

4. ADVANTAGES & DISADVANTAGES
Advantages:
• Conservation of Tooth Structure
• Appointment Time
• Resistance and Retention Forms(comparatively cusp coverage increase
fracture resistance. RFRF can be enhance by pins & slots)
• Economical
Disadvantages:
• Tooth Anatomy (difficult to achieve in large restoration)
• Resistance Form( not as effective as extra coronal restoration, more
difficult to develop)

5. CONTRAINDICATION & INDICATION
Contraindication:
• In significant occlusal problems
• Can not restored with direct restorations because of anatomical or
functional consideration
• Esthetic area
Indication:
• When large amounts of tooth structure are missing
• One or more cusps need capping
• Definitive final restorations
• Foundations
• Control restorations in teeth having questionable pulpal or periodontal
prognosis

6. Continued….
• Control restorations in teeth with acute or severe caries
• Resistance and Retention Forms
• Status and Prognosis of the Tooth
• Role of the Tooth in Overall Treatment Plan
• Occlusion
• Economical
• Age and Health of Patient

7. CLINICAL TECHNIQUE
There are three types of complex amalgam restoration:
1. Pin-Retained Amalgam Restorations
2. Slot-Retained Amalgam Restorations
3. Amalgam Foundations

9. Pin-Retained Amalgam Restorations
• Defined as any restoration requiring the placement of one or more
pins in dentin to provide adequate resistance and retention forms
• Have significantly greater retention compared with boxes or bonding
systems
INITIAL TOOTH PREPARATION:
• Outline form and initial depth, Primary resistance form ,Primary
retention form ,Convenience form
• In extensive caries , reduction of one or more of the cusps for
capping may be indicated
• When the facial or lingual extension exceeds two-thirds the distance
from a primary groove toward the cusp tip

10. Continued…….
• Depth cuts should be made on the remaining occlusal surface of each
cusp to be capped
• Depth cuts should be a minimum of 2 mm for functional cusps and
1.5 mm for nonfunctional cusps
• For less height cusps , depths cuts are less
• Goal is to ensure that the final restoration has restored cusps with a
minimal thickness
• When reducing only one of two facial or lingual cusps, the cusp
reduction should be extended just past the facial or lingual groove,
creating a vertical wall against the adjacent unreduced cusp

12. FINAL TOOTH PREPARATION:
• Removal of any remaining infected carious dentin or old restorative
material
• If a liner or base is used it should not extend closer than 1 mm to a
slot or a pin
• Pins placed into prepared pinholes , provide auxiliary resistance and
retention forms
• Coves and retention locks should be prepared when possible
• Locks and coves should be prepared before preparing the pinholes
• If required Slots prepared along the gingival floor, axial to the DEJ

13. TYPES OF PINS
1. Self-threading pin (frequently used)( most retentive)
2. Friction-locked ( rear)
3. Cemented pins (rear)
Diameter of the prepared pinhole is 0.0015 to 0.004 inch smaller
than the diameter of the pin
General guideline for pinhole depth is 2 mm
Thread Mate System (TMS) most widely used
Due to (1) versatility, (2) wide range of pin sizes, (3) color-coding
system, and (4) greater retentiveness
Pins are available in gold-plated stainless steel or in titanium

17. FACTORS AFFECTING RETENTION OF THE PIN IN
DENTIN AND AMALGAM
1. Type: Selfthreading pin is the most retentive
2. Surface Characteristics: Number and depth of threads on the pin
influence its retention
3. Orientation, Number, and Diameter: Placing pins in a non-parallel
manner increases their retention
• Avoid bending, bends may interfere with adequate condensation of
amalgam around the pin
• Pins should be bent only to provide for an adequate amount of
amalgam (approximately 1 mm) between the pin and the external
surface of the finished restoration

18. Continued……
• increasing the number of pins increases their retention in dentin and
amalgam
• As the number of pins increases, (1) crazing of dentin and the
potential for fracture increase, (2) amount of available dentin
between the pins decreases, and (3) strength of the amalgam
restoration decreases
• Diameter of the pin increases, retention in dentin and amalgam
generally increases
4. Extension into Dentin and Amalgam :Extension into dentin and
amalgam should be approximately 1.5 to 2 mm to preserve the
strength of dentin and amalgam

19. PIN PLACEMENT FACTORS AND TECHNIQUES
• Pin Size : Two determining factors for selecting the appropriate-sized
pin are the amount of dentin available to retention desired
• Number of Pins : Factors to consider (1) the amount of missing tooth
structure, (2) the amount of dentin available to receive the pins
safely, (3) the amount of retention required, and (4) the size of the
pins.
As a rule, one pin per missing axial line angle should be used
 Pins not required if only 2 to 3 mm of the occlusogingival height of a
cusp has been removed

20. Continued……
• Location : Factors aid in determining the pinhole locations (1)
knowledge of normal pulp anatomy and external tooth contours, (2) a
current radiograph of the tooth, (3) a periodontal probe, (4) the
patient’s age
Pinholes should be located near the line angles of the tooth, pinhole
should be positioned no closer than 0.5 to 1 mm to the DEJ or no
closer than 1 to 1.5 mm to the external surface of the tooth
First prepare a recess in the vertical wall with the No. 245 bur to
permit proper pinhole preparation and to provide a minimum of 0.5
mm clearance around the circumference of the pin
Pinholes should be prepared on a flat surface
The minimal inter-pin distance is 3 mm for the Minikin pin and 5 mm
for the Minim pin

22. Continued……
No.1/ 4 round bur is first used to prepare a pilot hole (dimple)
approximately one half the diameter of the bur at each location , for
accurate placement of drill
• Pinhole Preparation : Kodex drill (a twist drill) should be used
 It is color coded so that it can be matched easily with the
appropriate pin size
Drill is placed in the gingival crevice beside the location for the
pinhole and positioned such that it lies flat against the external
surface of the tooth; without changing the angulation obtained from
the crevice position, the handpiece is moved occlusally and the drill
placed in the previously prepared pilot hole

24. Continued……
Drill tip in its proper position and with the handpiece rotating at very
low speed (300–500 revolutions per minute [rpm]), pressure is
applied to the drill. The pinhole is prepared, in one or two
movements, until the depthlimiting portion of the drill is reached
• Pin Design : Several designs are available: standard, self-shearing,
two-in-one, Link Series, and Link Plus
Link Plus pins are self-shearing and are available as single and two-in-
one pins contained in color-coded plastic sleeves
This design has a sharper thread, a shoulder stop at 2 mm, and a
tapered tip to fit the bottom of the Pinhole
 It also provides a 2.7-mm length of pin to extend out of dentin,
which usually needs to be shortened
When the pin approaches the bottom of the pinhole, the head of the
pin shears off, leaving a length of pin extending from dentin

26. Continued…..
• Pin Insertion : Two instruments available: (1) conventional latch-type
contra-angle handpieces (2) TMS hand wrenches
Latchtype handpiece is recommended for the insertion of the Link
Series and the Link Plus pins
 Wrench is recommended for the insertion of standard pins
In latch-type handpiece pin is inserted into the handpiece and
positioned over the pinhole, handpiece is activated at low speed until
the plastic sleeve shears from the pin
Standard design pin is placed in the appropriate wrench and slowly
threaded clockwise into the pinhole until a definite resistance is felt
when the pin reaches the bottom of the hole
Pin should be rotated one-quarter to one half-turn counterclockwise
to reduce the dentinal stress created by the end of the pin

28. Continued……
Length of pin greater than 2 mm should be removed No. ¼ , No. ½ ,
or No. 169L bur, at high speed and oriented perpendicular to the pin
After placement, the pin should be tight, immobile, and not easily
withdrawn
Occasionally, bending a pin may be necessary to allow for
condensation of amalgam occlusogingivally, TMS bending tool placed
on the pin where the pin is to be bent, and with firm controlled
pressure, the bending tool should be rotated until the desired amount
of bend is achieved

30. POSSIBLE PROBLEMS WITH PINS
• Failure of Pin-Retained Restorations : it occur at five location (1)
within the restoration (restoration fracture), (2) at the interface
between the pin and the restorative material (pin– restoration
separation), (3) within the pin (pin fracture), (4) at the interface
between the pin and dentin, and (5) within dentin (dentin fracture)
• Broken Drills and Broken Pins : Twist drill breaks if it is stressed
laterally or allowed to stop rotating before it is removed from the
pinhole, removal is difficult
Treatment for broken drills and broken pins is to choose an
alternative location, at least 1.5 mm remote from the broken item,
and prepare another pinhole

32. Continued……
• Loose Pins : Occur in Self-threading pins, pin should be removed from
the tooth and the pinhole re-prepared with the next largest size drill
or Preparing another pinhole of the same size 1.5 mm from the
original pinhole also is acceptable
• Penetration into the Pulp and Perforation of the External Tooth
Surface : In an asymptomatic tooth, a pulpal penetration is treated by
applying calcium hydroxide liner over the opening of the pinhole, and
another hole is prepared 1.5 to 2 mm away
If the pin were left in the pulp, endodontic treatment recommended
Perforation of the external surface of the tooth can occur occlusal or
apical to the gingival attachment

33. Continued…..
Three options for perforations that occur occlusal to the gingival
attachment: (1) The pin can be cut off flush with the tooth surface
and no further treatment rendered; (2) the pin can be cut off flush
with the tooth surface and the preparation for an indirect restoration
extended gingivally beyond the perforation; or (3) the pin can be
removed, if still present, and the external aspect of the pinhole
enlarged slightly and restored with amalgam
Two options for perforations that occur apical to the gingival
attachment: (1) Reflect the tissue surgically, remove the necessary
bone, enlarge the pinhole slightly, and restore with amalgam, or (2)
perform a crown-extension procedure

34. Tooth Preparation for Slot-Retained
Amalgam Restorations
• Slot-Retained Amalgam Restorations : Slot is a horizontal retention
groove in dentin
can be used in conjunction with pin retention or as an alternative to
it
Slots are particularly indicated in short clinical crowns and in cusps
that have been reduced 2 to 3 mm for amalgam
Slots are less likely to create microfractures in dentin ,Shorter slots
provide as much resistance to horizontal force as do longer slots
No. 330 bur is used to place a slot in the gingival floor 0.5 mm axial of
the DEJ
slot is 1 mm in depth and 1 mm or more in length, depending on the
distance between the vertical walls

35. Continued.....
• Tooth Preparation for Amalgam Foundations : The retention for a
foundation must be sufficiently deep axially so that the final
preparation for the subsequent indirect restoration does not
compromise the resistance and retention forms of the foundation
• Restorative Technique:
Desensitizer Placement
Matrix Placement
Insertion
Contouring
Finishing of Amalgam