Complex amalgam

2. CONTENTS
• DEFINITION
• HISTORY
• CLASSIFICATION OF CORONAL TOOTH DESTRUCTION
• TYPES OF COMPLEX AMALGAM RESTORATION
• EXTRA RETENTIVE DEVICES
• INDICATIONS FOR PINS
• ADVANTAGES & DISADVANTAGES
• CLASSIFICATION OF PINS
• FACTORS AFFECTING RETENTION OF PINS
• PRINCIPLES OF PIN PLACEMENT
• COMPLICATIONS OF PIN PLACEMENT
• SLOT RETAINED AMALGAMS
• AMALGAM FOUNDATIONS
• AMALGAPINS
• RESTORATIVE TECHNIQUES
• CONCLUSION
• REFERENCES

3. Complex posterior restorations are used to replace missing tooth structure of teeth that
have fractured or are severely involved with caries or existing restorative material.
These restorations usually involve the replacement of one or more missing cusps, and they
often employ a bonding technique.
STURDEVANT

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

5. HISTORY

6. CLASSIFICATION OF CORONAL TOOTH
DESTRUCTION
Textbook of operative dentistry vimal sikri

8. TYPES OF COMPLEX AMALGAM
RESTORATIONS
• Pin-retained amalgam restorations
• Slot-retained amalgam restorations
• Amalgam foundations.

9. EXTRA RETENTIVE DEVICES
• To compensate the lost tooth structure , one or more than one retentive device is utilized
• The routinely used retentive devices are
Slots
Grooves/locks
Pins

10. SLOTS
• Slots are given to increase the surface area for the restoration
• 0.75-1.0 mm deep and 1.0-3.0 mm wide cut is given on pulpal and or cervical wall
• This rectangular depression in these walls increase the bulk for the restoration and also
increases the area for bonding
Dentinal slots are prepared approximately 1mm deep and 0.5-1 mm inside the dentinoenamel junction
(DEJ)

11. INDICATIONS
• Horizontal areas of short clinical crowns where loss of
vertical height is approx. 2-4 mm
• Slot retention may be used in conjunction with pin
retention ,or as an alternative to it

12. LOCKS
A retention lock is a prepared groove
whose length is in a vertical plane
and which is in dentin
Placement of retention locks .A) Position of No
169L bur to prepare the retention lock . B)Lock
prepared with No 14 bur

13. GROOVES/LOCKS
GROOVES LOCKS
• Given in direct restoration
• Extend upto pulpal wall
• converge occlusally
• Given in indirect restorations
• Extend upto cavosurface margins
• maintains the parallelism of walls
• Given at axiobuccal and axio- lingual line
angles
Wassell, Robert & Smart, E.R. & St George, Geoffrey. (2002). Crowns and other extra-coronal restorations: Cores for teeth with vital pulps. British dental journal.
192. 499-502, 505.

14. PINS
• In 1958 Dr Miles Markley introduced stainless steel pins to provide retention and resistance in
extensively decayed teeth.
• A pin retained restoration is defined as any restoration requiring the placement of one or more pins in
dentin to provide adequate and retention form . {Sturdevant }
• A pin is an extension of a restoration into a prepared hole or a metal rod secured in a hole drilled in
dentin for the purpose of retaining a restoration in or on the tooth {Atlas of operative dentistry }
• A pin is a small rod that fills into a channel drilled into dentin away from the pulp space .It is also
referred as a dentinal pin or a parapulpal pin {Richard J,shillingburg d.C.N.A }

15. RATIONALE
Pin help to support the restorative material and
resist their dislodgement in severely damaged and
weakened teeth
provide efficient and adequate retention with the
least sacrifice of healthy tooth structure
cavity preparation can also be limited to only
damaged surfaces thereby preserving esthetics and
contour
the use of pin is restricted for extra retentive
purposes
Pins are auxillary aids of retention

16. 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
• Control restorations in teeth with acute or severe caries

17. CONTRAINDICATION:
• In significant occlusal problems
• Can not restored with direct restorations because of anatomical or functional
consideration
• Esthetic area

18. ADVANTAGES:
• Conservation of tooth structure
• Appointment time
• Resistance and retention forms
• Economical

19. DISADVANTAGES
• Dentin fracture : use of pins in teeth where less dentin is present may result in stress in
dentin in the form of craze lines or cracks
• Strength of amalgam :compressive strength is not increased by use of pins ,but there is
decrease in tensile and transverse strength of amalgam
• Perforations :
• Microleakage
• Tooth anatomy

20. CLASSIFICATION
PINS
INDIRECT PINS /
PARALLEL PINS
CAST GOLD PINS
WROUGHT
PRECIOUS METAL
PINS
DIRECT PINS /NON-
PARALLEL PINS
CEMENTED PINS
FRICTION LOCKED
PINS
SELF THREADING
PINS

21. INDIRECT PINS
• Under sized to their pin holes
• integral part of cast restoration
• Parallel pins – method necessitates placement of pins parallel to each other as well as
parallel to the path of insertion of the restoration
• Less retention as compared to non parallel pins
TWO TYPES
 Cast gold pins
 Wrought precious metal pins

22. CAST GOLD PINS
• Relatively smooth surface
• Restoration using these pins are fabricated by keeping the nylon bristles or plastic pins
in the pin holes on which the rest of the restoration is built in the conventional form with
blue inlay wax.
• The whole assembly is then invested and casted with pins jamming an inherent part of
the restoration

23. WROUGHT PRECIOUS METAL PINS
• They have surface that is deformed by means of threaded or knurled patterns
• These pins are alloys of gold , platinum , palladium or platinum indium
• The pins are placed in the pinholes and are included in the wax pattern
• Their high melting point and tarnish resistance enable them to be incorporated into the
final gold casting
• These are 20-30 %more retentive than smooth cast pins

24. DIRECT PINS
• Made of stainless steel and inserted into dentin followed by the placement of a
restorative material like amalgam ,resin or cement directly over them
• Non parallel pins – can be inserted directly into the tooth structure
• 3 types
Cemented pins Friction locked pins Self threading pins

25. CEMENTED PINS
• Introduced by Markley in 1950s
• Pins are 0.0013”-0.0023” smaller than pin channels and the difference in
diameter provide space for cementing medium
• Indicated in cases where
• Least crazing and stress are desired in the remaining tooth structure
eg. Endodontically treated tooth
• Bulk of dentin to accommodate the pin is limited
• Dentin has lost its elasticity because of sclerosis or dehydration
• When pin has to be placed near dentinoenamel junction.
• Preferred technique in class IV preparation

26. TECHNIQUES
Self centering spiral drill
mounted in a low speed
handpiece is used to prepare
the pin channel
Desired length of pin is cut
extraorally
Depth to which pin channel
has been drilled is marked in
the pin
Dry the prepared pin
channels with endodontic
paper points. • Place cement
mix into pin channel with a
root canal file or/an explorer
or a lentulo-spiral running at
slow speed of 1000 rpm
Hold the pin in forceps and
coat with cement. • Insert the
pin into hole
Hold the pin in its position till
it sets. • Remove excess
cement with an explorer.

27. ADVANTAGES
• Cemented pins are approximately 0.001”-0.002” smaller than their pinholes and hence are more
likely to be seated to the full depth of the hole
• They are passively retained in the dentin
• Cement seals the interface between the pin and the tooth chances of microleakage are reduced
• These can be cut or bent to their final configuration before fixing them in the pin holes

28. DISADVANTAGES
• They offer less retention compared to the friction locked and threaded pins
• It is often difficult to insert cement into the pinhole and later locate the hole after cement has been
introduced
• A poorly cemented pins is easily dislodged when the filling material is being inserted
• Greater time is required for the mixing and hardening of the cement

29. FRICTION LOCKED PINS
• Introduced by Goldstein in 1966
• Pins are 0.001” larger than their pin channel and hence utilize the
elasticity of dentin for retaining the tapped pins in a wise like grip
Indication
• Teeth that are vital and periodontally sound
• where direct access is possible so that the tapping force can be
applied parallel to the long axis of the pins .
• when sufficient amount of dentin is available to surround the pin
and in no way should they be placed closer than 1.5 mm to the dej

30. TECHNIQUES
Remove
excess length
with a small
round bur.
Apply force
with mallet
parallel to long
axis of pin until
pin reaches
desired length
Insert the pin
into a pin setter
and carry to
pinhole
Cut the pin to
desired length
before
insertion

31. ADVANTAGES
• Cement is not required
• Pins acquire stability from the moment they are inserted
• Better retention than the cemented pins

32. DISADVANTAGES
The length of the pin is judged by trial and error - it cannot be removed from dentin for
cutting to the desired length once inserted
 Bending or contouring of the pin after it has been inserted into the pinhole leads to
further stresses
 Driving pins into their respective pinholes generates stresses in dentin in the form of
cracks or craze lines
Many a times , the pin do not reach the full depth of the channel because of gouging and
hence may lose some of their retentive capacity
Microleakage is higher than for cemented pins if the overlying restoration leaks

33. THREADED PINS
• Introduced by Going in 1966
• Pins are 0.0015-0.002” larger than their pin channel they are retained by
the elasticity of dentin
• They actively engage the tooth structure through their threads similar to a
screw inserted into a wooden block
• Most popular due to their ease and rapidity of insertion and maximum
retention offered
Indicated in
• Vital teeth and where maximum retention is needed
• when sufficient amount of dentin is available to surround the pins

34. ADVANTAGES
• Ease of insertion
• Superior retention
• Require less depth for placement
• Require no cementing medium

35. DISADVANTAGES
• Generate great stresses in dentin in form of craze or crack lines.
• Pins may fail to seat completely.
• If pin is forced into pinhole, it may strip the sides of dentin resulting in loose fit.
• Microleakage is higher than cemented pins if the overlying restoration leaks.
• If pin is to be bent, cut or contoured after placement, it generates extra stress on the
tooth or loosens the pin.

36. CEMENTED PINS
FRICTION
LOCKED PINS
SELF THREADED
PINS
Stainless steel with
threads or serrations
Stainless steel with
threads
Stainless
steel/Titanium with gold
plating
Pin channel [0.020” to
0.32”] larger than pin
size [0.018” to 0.30”]
Pin channel is 0.001”
smaller than pin size
Pin channel is 0.015”
to 0.004” smaller than
pin size
Luted with standard
luting agents
Taped into place with
mallet
Placed by hand wrench
or contra angle hand
piece
Ease of placement Pin placement is
difficult
Pin placement is easy

37. CEMENTED PINS FRICTION
LOCKED PINS
SELF THREADED
PINS
Less internal
stresses
Increased internal
stress
Increased internal
stresses but less as
compared to friction
locked pins
Least retentive 2-3 times more
retentive than
cemented pins
5-6 times more
retentive than
friction locked pins

38. THREAD MATE SYSTEM (TMS)
It is the most widely used self-threading pin because of its:
1. Versatility of design
2. Wide range of pin sizes
3. Colour coding system,
4. Greater retentiveness
5. Gold plated surface finish, which may eliminate the possibility of corrosion

39. Four varieties of
threaded pins
depending on their size
in decreasing order as
Regular- 0.030”,0.031” Minim – 0.024”,0.025” Minikin – 0.019”,0.020 Minuta – 0.014”,0.015”
THREAD MATE SYSTEM (TMS)

40. Four basic
design of
threaded pins
Standard
design
Self shearing
single pin
design
Two –in-one
design
Disposable
latch head
design

42. REGULAR
Largest diameter pin among thread mate system pins.
It is rarely used
Disadvantages: –
great amount of stress and crazing around pins. –
More chances of perforation in pulp chamber.

43. MINIM PIN
This pin is also preferred in some cases, depending upon the availability of dentin
because: – it provides less dentinal crazing as compared to regular pins
it is used in cases where pinholes for minikin gets over-prepared.

44. MINIKIN:
The pin of choice in grossly decayed posterior teeth because of:
– Less dentin crazing
– Better retention
– Lesser chances of pulp involvement
– Lesser chances of periodontal perforation

45. • MINUTA:
Smallest in size among self threaded pins.
It is too small to provide retention in the tooth. I
Rarely used nowadays

46. DESIGNS
Standard
Self-
shearing
Two-in-
one
Link
series
Link plus
series.

47. STANDARD DESIGN
• The standard pin is a full length pin ie .7 mm long which can be cut to the required length after
placement
• It provides flattened head for engagement with the hand wrench or the hand piece chuck
• It is threaded to place until it reaches the bottom of pinhole as judged by tactile sense
Advantages
 It can be reversed one quarter to one half turn Following insertion to full depth
to reduce stress created at the apical end of the pinhole
 Pin height can be cut to appropriate length after placement

48. SELF SHEARING DESIGN
• Available in varying length depend upon the diameters
• The pin is designed so that when it reaches the bottom of the pinhole, the head
separates automatically at the shear line,leaving a portion of it to project from the
dentin
• Shearing occurs when there is marked resistance to turning ie pin insertion is torque
limited

49. TWO-IN-ONE DESIGN
• In this, two pins are connected each other at a joint. This joint marks the shear line for
peripheral pin.
• Length of two-in-one pin is approximately 8-9 mm with two pins of equal lengths.
• It has a flat head to engage the hand wrench or the handpiece chuck.
Out of the two pins, one which is released
first-pin a or the peripheral pin
second- pin or the wrench attachment pin
Advantage – hand piece need not be reloaded during two pin insertions

50. LINK SERIES PIN
• Disposable latch head design has a plastic sheath/head designed to fit in a slow speed
contra angle handpiece.
• Pin appears to lie freely in the plastic sheath.
• This helps in self-alignment as pin engages the pinhole.
• When pin reaches bottom of the pinhole, there is resistance which causes the separation of
head from the pin at the shear line.
• Plastic sheath is then discarded

51. LINK PLUS DESIGN
• Link plus series pin design has the following modifications from link series:
• incorporation of sharper threads
• tapered tip which readily fits in pinhole
• shoulder stop.

52. ADVANTAGES
• Multipurpose designs
• Wide variety of pin sizes
• Good retention
• Color-coding system for easy identification and use
• Gold plating for good surface finish and also for reducing corrosion.

53. FACTORS AFFECTING RETENTION OF PINS IN TOOTH
STRUCTURE
PIN DIAMETER
• Retention is directly proportional to diameter of pin
• However, overzealous increase in diameter may decrease amount of dentin and thus
weaken the tool.
PIN NUMBER
• Increase in number of pins increases the retention in dentin.

54. PIN TYPE
• Cemented pins are least retentive. Friction locked pins show intermediate retention and
threaded pins are the most retentive.
• Friction locked and threaded pins are retained by elasticity of dentin and this accounts
for their higher retention.
PIN DEPTH IN DENTIN
• Increasing the depth of pin in dentin increases the retention.

55. CEMENTING AGENTS
• Zinc phosphate cement is more retentive than polycarboxylate and zinc-oxide eugenol
cements.
• Glass ionomer cement is also more retentive.
• varnish reduces the retentive ability of the cemented pins.

56. ASSOCIATION BETWEEN PIN CHANNEL AND PIN CIRCUMFERENCE
• Poor quality in the manufacture of pins can result in problems like mismatch between the
pin and drill diameters, variations in the inside diameter and thread shapes of the pins,
etc.
TYPE OF DENTIN
• Young resilient primary dentin offers more retention than secondary dentin.

57. FACTORS AFFECTING RETENTION OF PINS IN
RESTORATIVE MATERIAL
PIN LENGTH
• Increase in length of the pin in restorative material increases the retention.
PIN NUMBER
• Increase in number of pins, increases the retention of restoration.
• Excessive increase in the number of pins makes condensation of restorative material
difficult and decreases the overall strength.

58. PIN DIAMETER
• Retention increases with increase in diameter of the pin.
PIN ORIENTATION
• It also affects retention, for example, pins placed in non-parallel increase retention.
PIN SHAPE
• retention cleats and square or pear-shaped heads on the pins improve retention of pin.

59. INTERPIN DISTANCE
• Placing pins close to each other (minimum interpin distance 2 mm) increases retention. If
distance is lesser than 2 mm, pin retention is reduced because of the less amount of
material present in between the pins and increase in residual stresses in dentin

60. PIN RESTORATION INTERPHASES
• An ideal interphase between pin and material is one which is not interrupted.
when gold plated stainless steel pins are to be used with silver amalgam, gold
should be pure for mercury to react with it.
When silver plated stainless steel pins are used with amalgam, voids are seen at
interphase because mercury (of amalgam) reacts with silver plating and dissolving
it.

61. SURFACE CHARACTERISTICS
• Number of serrations present on pin surface affects its retention.
• Serrated pins are more retentive than smooth pins.
BULK OF MATERIAL SURROUNDING THE PIN
• Pin retention is directly proportional to bulk of material surrounding the pin.
• Retention is almost lost when the material around the pin is less than half the diameter of
the pin.

62. PRINCIPLES OF PLACEMENT OF PINS
• NUMBER OF PINS
• PIN SITE
• PIN ORIENTATION
• PIN DIAMETER
• PIN LENGTH
• INTER PIN DISTANCE

63. NUMBER OF PINS
• Increase the no of pins increase the chance of stress , pulpal damage and or
perforations , hence aim should be to achieve adequate retention with minimum
possible number of pins

64. UNNECESSARY USE OF PINS CAUSES
• Stress in the tooth resulting in fracture of tooth
• voids in restoration
• Decrease in available interpin dentin
• Decrease in strength of amalgam restoration.

65. PIN SITE
• Knowledge of normal pulp anatomy to avoid pulpal exposure or external tooth
perforations
• avoid placing the pins directly under occlusal loads as this may weaken the amalgam
• Pinhole should be at least 0.5 mm inside the dentin to reduce chances for crazing of
tooth structure
• Pinholes should be located on a flat surface, which should be perpendicular to the
direction of pinhole or on less angular surface

66. • when more than two pinholes are planned, they should be placed at different levels to
prevent stresses in same transverse plane of the tooth
• If two or more pins are to be placed, interpin distance should be such that it results in
lower levels of stresses in dentin and restorative material around pins can be
manipulated
• there should be at least 1 mm of sound dentin around circumference of the pin

67. • There should be at least 1 mm of dentin between pulp and the pin to avoid pulpal
damage
• Intermittent radiographic monitoring should be done constantly, while preparing and
placing the pins.

68. LOCATION OF PINS
FACTORS THAT AID IN DETERMINING PINHOLE LOCATIONS:
Knowledge of normal pulp anatomy and external tooth contours,
 a current radiograph of the tooth,
 a periodontal probe, and
 the patient's age

71. • Most desirable location : facio/linguoproximal line angles or corners of the tooth
• Least desirable location: middle of the facial , lingual , mesial and distal surface of a
tooth
• Placing pinholes overlying furcation and concavities – hazardous
• the site should be half way between the pulp and dentino-enamel junction/external
surface of the tooth

73. • Pinholes should be located near the line angles of the tooth,
• The pinhole should be parallel to the adjacent external
surface of the tooth.
• Pinholes should be located halfway between the pulp and
the dej or external surface of the tooth root
• The 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, whichever distance is greater

74. A non–depth-limiting pin channel drill is
aligned parallel to the external surface
Pinhole position. Position relative to
Dej (a). Position relative to external tooth surface (B).

75. A, pin placed too close to vertical wall such that adequate condensation
of amalgam is jeopardized, b and c, prepare recessed area in vertical
wall of mandibular molar with no. 245 bur to provide adequate space
for amalgam condensation around pin.

76. PIN SIZE :
• Two determining factors for selecting pin size:
• The amount of dentin available
• The amount of retention desired.
• The pins of choice for severely involved posterior teeth are the minikin (0.019 inch [0.48 mm])
and, occasionally, the minim (0.024 inch [0.61 mm]).
• Of the four pin sizes, the regular pin caused the highest incidence of dentinal cracking that
communicated with the pulp chamber.
(WEBB EL, STRAKA WF, PHILLIPS CL. J PROSTHET DENT 61(5):624-628, 1989.)

77. LENGTH OF PIN INTO DENTIN AND AMALGAM
• Pin extension of 2 mm into dentin and amalgam provide maximum required retention.
• Pin extension more than 2 mm is avoided so as to preserve the strength of dentin and
the restoration
• Care should be taken when pins are placed in cusp coverage areas, they should extend
minimally into restorative material.
• To prevent overextension of pins, depth limiting drills, or pin bender to reduce length of
pin should be used

79. PIN ORIENTATION
• Pins should be oriented parallel to the long axis of the tooth.
• in excessively cervically placed areas towards the cemento-enamel junction where
sharp constrictions are likely to be present and dentin thickness is reduced, it is
mandatory to direct the pin parallel to the closest external surface of the tooth and then
bend it slightly as needed.
• . The best possible way to determine presence of any abnormal contours is to place a
probe adjacent to the surface close to the intended location and examine its direction.
• Radiographs can also be helpful.

80. PIN DIAMETER
• The diameter of the pin depends upon
(a) The amount of dentin available
(b) The size of the concerned tooth
(c) The amount of retention required.
Increasing the diameter of the pin offers increased retention

81. INTER-PIN DISTANCE
• Spacing between pins, or the interpin distance, must be considered when two or
more pinholes are prepared.
• The optimal interpin distance depends on the size of pin to be used.
• The minimal interpin distance is 3 mm for the minikin (0.019 inch [0.48 mm]) pin
and 5 mm for the minim (0.024 inch [0.61 mm]) pin.
• Maximal interpin distance results in lower levels of stress in dentin

83. PINHOLE PREPARATION
• The kodex drill (a twist drill) should be used for preparing pinholes-
• A depth-limiting drill should be used to prepare the hole – to achieve optimal depth of
pin in dentin-2mm
• Prepare a hole on a flat surface that is perpendicular to the drill- only then the correct
depth will be prepared.

84. PINHOLE PREPARATION.

85. PINHOLE PREPARATION

86. PINHOLE PREPARATION
Certain clinical locations require extra care in determining pinhole angulation
• Distal of mandibular molars and the lingual of maxillary molars
• Teeth that are rotated in the arch
• Teeth that are abnormally tilted in the arch-
e.g mesially tilted mandibular 2nd molars.

87. ARMAMENTARIUM FOR PIN INSERTION
• Two instruments for the insertion of threaded pins
• Conventional latch type contra angle handpieces
• TMS hand wrenches
• Latch type hand piece – link series and link plus pins
• Hand wrench – standard pins

88. HAND WRENCH
• Provides tactile sense during threading of pin into
dentin
• insertion of standard pin
Hand wrenches for the thread mate
system (TMS) pins.
A Regular and Minikin
B Minim
C Minuta
D Link series and Link plus

90. CONVENTIONAL LATCH TYPE CONTRA-ANGLE HANDPIECE
• A 10:1 reduction gear contra-angle hand piece is
available to insert the pins
• During the insertion of the pins the low speed hand
piece increase the tactile sense of the operator
• It also reduces the risk of stripping the thread in the
dentin once the pin in place
• Latch type hand piece – insert a link series or link
plus pin

94. Placement of cemented
pins.
• Prepare pinholes with appropriately sized twist drill.
• Cut proper length of pin with wire-cutting pliers.
• Slightly round the end of the pin with rotating
carborundum disk.
• Place pins in tooth, and evaluate need for bending.
• Hold pin with two pairs of pliers, and bend as
necessary.
• Pins bent.
• Convey cement into pinholes with a lentulo spiral
instrument.
• Pins cemented

95. FAILURE OF PIN-RETAINED RESTORATIONS
• The failure of pin-retained restorations might occur at any of five different
locations:
• Within the restoration (restoration fracture)
• At the interface between the pin and the restorative material (pin-restoration
separation)
• Within the pin (pin fracture),
• At the interface between the pin and the dentin (pin-dentin separation)
• Within the dentin (dentin fracture)
• Failure is more likely to occur at the pin-dentin interface than at the pin-
restoration interface

96. WITHIN THE RESTORATION
• Restoration may fracture because of improper condensation, trituration or manipulation

97. WITHIN PIN
• Pin fracture may occur because of improper pin placement
technique
Pin fracture can occur in the following conditions:
• During bending or if turned more than required in the pinhole
• Excessive force is applied while its placement
• Pin is rotated despite being fully seated in the pinhole.
Removal of broken pins and drills is difficult. It is best to choose another site about 1.5 mm away
from the previous site and leave the broken pin as if it is not interfering in occlusion or condensation
of amalgam.

98. AT PIN RESTORATION INTERFACE
• Restoration may pull away from pin because of
corrosion products at pin restoration interface

99. AT PIN TOOTH INTERFACE
• Pin may separate along with restoration because of
improper pin tooth joint
• more common than at pin-restoration interface

100. WITHIN TOOTH
• Dentinal fracture can occur because of
concentration of internal stresses because
of improper selection of pin according to
dentin type.

102. PROCEDURAL PROBLEMS ENCOUNTERED
• BROKEN DRILLS AND BROKEN PINS.
• LOOSE PINS.
• PENETRATION INTO THE PULP AND PERFORATION OF THE EXTERNAL TOOTH
SURFACE.

103. BROKEN DRILLS AND BROKEN PINS
• A twist drill breaks if it is stressed laterally or allowed to stop rotating before being
removed from the pinhole. -Use of sharp twist drills helps eliminate the possibility of
drill breakage.
• The standard pin usually breaks if turned more than needed to reach the bottom of the
pinhole
• The treatment for broken drills and broken pins is to choose an alternate location, at
least 1.5 mm remote from the broken item, and prepare another pinhole.
• Removal of a broken pin or drill is difficult, if not impossible, and usually should not be
attempted. The best solution for these two problems is prevention.

104. LOOSE PINS
Loose pins can occur in the following conditions:
• repeated insertion and removal of drill during pin preparation
• pin drill is rotated more than required
• pinhole is too large
• manufacturer’s discrepancy, i.e. Poor quality control between pin drill and pin size
• Pin failed to be driven in the pinhole resulting in stripped out or chipping of dentin or enamel.

105. PULPAL PENETRATION
• Pin placement can also result in pulp and periodontal perforation
• Perforation is indicated by sudden bleeding while operating the drill
.
• Penetration or perforation can be verified by radiograph.
• If pulpal penetration occurs, and tooth is asymptomatic with very
little bleeding, do direct pulp capping and prepare a fresh hole.
• If tooth has extensive restorations or caries, root canal treatment
should be done in case of pulpal exposure.

106. PERFORATION OF THE EXTERNAL TOOTH SURFACE.
• 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;
(3) The pin can be removed, if still present, and the external aspect of the
pinhole enlarged slightly and restored with amalgam

107. 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
(2) Perform a crown-extension procedure

108. External perforation of pin. A, radiograph showing external perforation of pin. B, surgical access
to extruding pin (arrow). C, pin cut flush with tooth structure and crown lengthening procedure
performed. D, Length of pin removed

109. SLOT-RETAINED AMALGAM
RESTORATIONS.

110. SLOT-RETAINED AMALGAM
RESTORATIONS.
• Slots are horizontally prepared channels in dentine.
• The slot is at least 0.5 mm in depth and 1 mm or more in length depending on the
distance between the vertical walls
• placed on the facial, lingual, mesial, and distal aspects of the preparation
• The slot may be continuous or segmented, depending on the amount of missing tooth
structure.
• Shorter slots provide as much resistance to horizontal force as do longer slots.
• Slots can be used in combination with pins to generate additional retention and
resistance forms.

112. SLOT PREPARATION
• A no. 33'/2 (inverted cone) bur is used to place a slot in the gingival floor 0.5 mm axial of
the DEJ.
• An alternative technique is to prepare the slot initially with a no. 169L bur. Then, ensure
its convergence by refining it with a no. 331/2 bur.

113. 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

114. AMALGAM FOUNDATIONS

115. AMALGAM FOUNDATIONS
• A foundation is an initial restoration of a severely involved tooth. The tooth is restored so that
the restorative material (amalgam, composite, or other) will serve in lieu of tooth structure to
provide retention and resistance forms during the development of the subsequent final cast
restoration.
• A foundation is indicated for a tooth that is severely broken down and lacks the resistance
and retention forms needed for an indirect restoration
• Foundations are placed in preparation for a full crown, especially in endodontically treated
teeth.

116. AMALGAM FOUNDATIONS
• The amalgam foundation restorations mainly rely on chamber retention.
• If the height of available pulp chamber is 4-6mm adequate retention can be gained by
filling from the orifices.
• If the height of available pulp chamber is 2mm or less extension into the root canal space
2 to 4 mm is recommended

119. AMALGAPIN
• Concept of amalgapin was given by Shavell in 1980 to allow amalgam to act as retentive pins.
• Amalgapins are vertical posts of amalgam anchored in dentin
• Pits prepared in dentin are shallow and little wider than pinholes. These are called ‘dentin
chambers’. Post formed by amalgam in dentin chamber is called ‘amalgapin’.
• Dentin chamber is prepared by using inverted cone bur on gingival floor 0.5 mm in dentin with 1 to
2 mm depth and 0.5 to 1 mm width.
• Amalgapins increase the retention and resistance of complete restoration. They also increase the
bulk of amalgam.

120. RESTORATIVE TECHNIQUES
use of desensitizer or
bonding system
Matrix placement
Inserting the amalgam
contouring and finishing
the amalgam

121. USE OF DESENSITIZER OR BONDING
SYSTEM
• Once prepataion completed ,clean the preparation
• Inspect for detection and removal of debris
• To reduce dentin permeability and seal the dentin – use dentin desensitizer

122. MATRIX PLACEMENT
• Universal matrix ;
• The tofflemire retainer and band can be used successfully for the majority of posterior
amalgam restorations
• It requires sufficient tooth structure to retain the band after it is applied .

123. AUTOMATRIX
• Retainerless matrix system for any tooth regardless of its circumference and height
• automatrix band supplied in three width
• 3/16 inch
• ¼ Inch
• 5/16 inch

124. ADVANTAGES
• Convenience
• Improved visibility because of absence of retainer
• decrease time for applications as compared to copper band matrix
• Ability to place the autolock loop on the facial or lingual surface of the tooth

125. DISADVANTAGES
• Band is flat and difficult to burnish
• Development of proper proximal contours and contacts can be difficult with the
automatrix bands

126. INSERTING THE AMALGAM
• High copper alloy is strongly recommeneded
• Spherical alloys can be condensed quickly with pressure to ensure good adaptation around the
pins
• Proximal contacts may be easier to achieve with admixed alloy because of their condensabilty

127. FINISHING AND POLISHING PROCEDURE
• Objective of polishing is refinement of the margins, development of the contour and smoothening
of the surface.
• Polishing must be done after 24 hours of restoration placement.
• Round steel finishing bur or small wheel diamond is used to contour the occlusal restoration.
• Silica or aluminum oxide is applied by prophylactic cup to polish the surface

128. CONCLUSION
• Planning the restorative treatment of badly broken down teeth with vital pulps
• The prognosis of involved tooth and its role in the overall treatment plan help to decide
the restoration to be placed
• If amalgam is selected as the restorative material pin placed in dentin improve the
retention
• studies now leads to the conclusion that the deleterious effect of pins outweighs their
benefits .Alternative methods of retention and other options are considered

129. REFERENCES
• Eberting JJ. A review of the amalgapin technique for complex amalgam restorations.
Gen dent. 2000 jan-feb;48(1):92-5.
• Operative dentistry modern theory and practice m a marzouk
• Textbook of operative dentistry – vimal k sikri
• Sturdevant’s art & science of operative dentistry
• Textbook of operative dentistry-Nisha Garg
• Clinical operative dentistry –principles and practice