This document reviews literature on factors that influence the selection of post and core systems for restoring endodontically treated teeth. It identifies several key factors to consider, including root length and anatomy, amount of remaining coronal tooth structure, post design, material properties, and stresses. The review recommends using custom cast posts for moderate to severe tooth structure loss or irregular canals. Prefabricated parallel-sided posts are preferred for small circular canals. An ideal post system maximizes retention while minimizing tooth structure removal and stress concentrations. The conclusion is that the most appropriate post system should be selected based on the individual tooth needs.
Low Rate Call Girls Pune Esha 9907093804 Short 1500 Night 6000 Best call girl...
Factors Determining Post and Core Selection
1. FACTORS DETERMINING POST
SELECTION
A LITERATURE REVIEW
Aquaviva Fernandes, Sharat Shetty, Ivy
Continho.
JPD 2003;90:556-62
Dr Talib Amin
GDC Srinagar
2.
3. Greater tooth loss in endodontically treated
teeth is due to
Caries/Pathological disease
Endodontic treatment
Previous restoration
Loss of tooth structure compromises retention of
subsequent restoration and increases chances of
fracture during functional loading
4. Longevity of endodontically involved
teeth has been greatly enhanced with
the use of intra radicular devices
varying from
conventional custom cast post to
one visit techniques using pre
fabricated post systems
6. Sufficient tooth structure GROSS
DESTRUCTION
Simple restoration POST & CORE
RESTORATION
FACTORS INFLUENCING CHOICE OF
TREATMENT
Type of tooth (anterior or posterior)
Amount of remaining tooth structure
8. POST-AND-CORE:
A one-piece foundation
restoration for an
endodontically treated tooth
that comprises a post within
the root canal and a core
replacing missing coronal
structure to form the tooth
preparation.
(GPT 8)
9. POST & CORE
Provides retention & support for
cast restoration
Post retains core
Core replaces missing tooth
structure
10. TYPES OF POSTS
Method of
fabrication
Prefabricated
Custom
made
Material used
Metallic
Non
metallic
19. ROOT LENGTH
Determines length of post
Greater the post length, better the
retention and
stress distribution
(Holmes et al JPD1996;75:140-7)
3-5 mm of GP in the apical region to
maintain
apical seal
(Mattison et al JPD 1984; 51: 785-9)
20. Parallel sided threaded post or
Reinforced composite luting
agents can compensate for
reduced post length
(Nissan et al JPD 2001 ;86 : 304 -
8)
For short rooted molars more than
one post will provide additional
retention for core.
21. Variations in terms of root curvature, MD
& LL widths
Root anatomy dictates post selection
Improper post space preparation and use of
large diameter post may cause apical or lateral
perforation
Radiographic assessment is important to
evaluate root
length, width and canal structure
Roots of maxillary centrals and
laterals, mandibular premolars have
TOOTH ANATOMY
22. POST WIDTH
Factors to be considered:
Preservation of tooth structure
Reduction of perforation
Resistance to fracture
Approaches regarding selection of post
diameter
o Conservationist
o Preservationist
o Proportionist(Lloyd & Palik JPD 93) (Tilk et al J Endod
JPD 82) (Pilo, Tamse JPD 2000)
23. PROPORTIONIST
APPROACH
Post width should not be more than
1/3rd
root width at its narrowest
dimension
(Stern & Hirshfeld JPD 73)
Advocated to preserve tooth
26. Increase in post width has no
significant effect on retention
(Standlee et al JPD 1978)
Large diameter posts provide
least resistance to fracture
(Trabest, et al J Endod
1978)
27. CANAL CONFIGURATION &
POST ADAPTABILITY
Canal configuration determines whether to
use
custom designed or prefabricated post
Post should
o Fit closely
o Aptly conform to canal shape & size
o Less dentin removal
o Enhance fracture resistance
28. Funnel shaped canal
Parallel-sided posts & fill remaining space
with cement
Tapered post
Large prefabricated parallel sided post
Canals requiring extensive preparation
Cast post and core is more retentive than pre
fabricated
(Cohen et al JPD 1996)
Wide canal root
Reinforcement with composite
(Scurpe et al QI 1996)
29. Well adapted tapered posts
Increased resistance to fracture
(Sorensen et al JPD 1990)
( Jan, Whang JPD 1985)
More extensive tooth loss on fracture
Custom cast posts success rate of 90%
after 5 yrs
in fracture
(Morgano, Milot JPD 1993)
30. CORONAL
STRUCTURE
1.5-2mm of coronal tooth
structure to achieve resistance form
Non-metal posts (carbon fiber)
Can be used only when ample
Coronal dentin remains and crown is
well supported
Inferior stength
Cast Post & Core
31. 1.5-2mm of coronal tooth
structure to achieve resistance
PREPARED WITH A
FERULE (ARROW)
32. STRESS
Compressive
Tensile
Shear --- most detrimental
Inc. post length
minimum diameter
•Reduces
shear
strength
•Preserves
tooth
structure
•MoreHolmes et al JPD 1996
33. TORTIONAL FORCE
May cause loosening and
displacement of post from canal
failure of post & core system
Anti rotational features
provide resistance
integral for survival of
post & core system (Burgess et al
JPD 1992)
34. modulus of elasticity
are stiffer and transmit
forces directly to the
tooth interface with
shock absorption
(No Damping Effect)
E Zirconia> E Carbon
Post
Fracture is less with
35. HYDROSTATIC
PRESSURE
Cementation enhances retention, stress
distribution, seals irregularities & increases
pressure within the canal
Depends on viscosity of cement
Prevents complete seating of post
Can cause fracture of root
PREVENTION
“Cement vent” design in post for excess
Tapered posts are self venting
36. POST DESIGN
o According to shape:
1. Parallel
2. Tapered
3. Combination
o According to surface characteristics:
1. Active posts
Engage mechanically into dentin with
threads
2. Passive posts
Depend on cement and close adaptation
in canal for retention
37. Active posts
More failures
Tapered posts
Preservation of tooth structure
Wedging effect
Stress concentration at coronal portion of root
Lower retentive strength
Parallel sided post
Increase retention
Uniform stress distribution along post length
38. Combination (parallel
tapered)
Stress conc. Is found at apex of canal
due to un necessary removal of tooth
structure at the apical end and sharp
angles of post
This type of post is parallel
throughout the length except for the
most apical portion
Preservation of dentin at apex
39. Threaded posts
inferior to custom casts
exert a greater stress
Parallel sided, serrated and
vented posts exert least
amount of stress
41. To prevent placement stresses by threaded
posts
Pre tapping post channels
Limiting the no. of threads
Counter rotating the post by ½ turn after full
engagement
Incorporating split shank mechanism
(Cohen, Musikant, Deutsh JPD 1994)
42. POST MATERIAL
Physical properties of material should be similar
to dentin
Bond to tooth structure
Biocompatible
Shock absorber
METAL POSTS
NON METAL POSTS
o Metal and other rigid posts resist
greater forces without distortion ;potential
43. Carbon fiber posts
exhibit mechanical properties similar
to
those of tooth
absorb and dissipate stress
inferior strength than metal posts
44. Zirconium posts
High modules of
elasticity
No shock absorption
More root fractures
than carbon fiber posts
45. MATERIAL
COMPATIBILITY
Ideally made from same alloy
Dissimilar core and post material create galvanic
current and corrosion & accumulation of
corrosion products can increase volume and cause
root fracture
(Peterson J Can Dent Ass 1971)
Causes of corrosion of post
• Access of an electrolyte to post surface through Cementum &
dentin
•Micro leakage around coronal restorations
•Accessory canals which have opened during post preparation
46. Titanium alloy posts are most corrosion
resistant
Alloys containing brass have low
corrosion resistance
Noble metal alloys are corrosion
resistant but
expensive
47. BONDING ABILITY
Single unit tooth-post-core-crown
system
Difficult due to difference in
physical properties of materials and
tooth structure
Traditional cements produce only
frictional resistance (Zinc phosphate)
Newer adhesive resins bond post to
tooth stucture
48. Bonding of post to
tooth
Improve prognosis of post core by
improving retention
Reinforce tooth structure (Distribution
of stress
by bonding material)
•Nature of material is responsible for bonding
of post to tooth structure adhesion
•Carbon fiber & glass fiber post adhere better
with resin luting cements than Zirconia posts
49. CORE RETENTION
core replaces missing tooth structure
main function of post is to retain core
design of head of post should provide adequate
retention &
resistance
Design of core
• crenellated
• flat
• spherical
50. As the no. of interfaces increases the
potential for failure also increases
Prefabricated posts with direct cores
are less reliable than one piece cast post
and core
51. RETRIEVABILITY
Ideally post system should be easy to retrieve
without any substantial loss of tooth structure if RCT
fails or post fractures
cast metal posts are difficult to retrieve ,
involves removal of tooth structure around the post
Carbon fiber posts are easy & rapid to remove
Zirconia posts are more difficult to remove
Use of conventional rotary instruments &
solvents for removal
more preservation of residual dentin
minimizes chances of perforation
52. Certain post systems facilitate easy removal
by providing a milled head, a wrench &
retrieval drills
Other commercially available systems
are
Messeran kit
Post removal system
Endodontic extractors
Ultrasonic devices
53. ESTHETICS
Post and core material should be esthetic
compatibility with crown and surrounding tissue
custom cast posts provide grey tint
composite core material with prefabricated metal
posts aid
in masking color of post
54. Masking depends on thickness of core
Ceramic crown with opaque substructure
can be used when complete masking is
difficult
Metal ceramic crown allows use of any
post and core
All ceramic are translucent and allow
metal to show through
Opaque porcelain fused to core
eliminates the grayish effect of cast
58. 1.Physical properties similar to
dentin
2.Maximum retention with little
dentin removal
3.Even distribution of functional
stresses along root surfaces
4.Esthetic compatibility
5.Minimum stress during
displacement and cementation
59. 6. Resistance to displacement
7. Good core retention
8. Easy retrievability
9. Material compatible with
core
10. Ease of use, safety &
reliability
60. Use of reinforced composite resin
cement significantly increases
retention of parallel sided posts &
tapered posts when compared to
zinc phosphate cement
Parallel sided posts had greater
increased retention than tapered
posts
Nissan ,dmitry, assif JPD
61. o Titanium system posts
least fracture resistance
most catastrophic failures
o Quartz fiber posts
higher fracture resistance
o Glass fiber & zirconia posts
fracture loads did not vary
Akkayan, Gulmez JPD,2002
62. This review identified
factors that influence the
selection of the post &
core system and offers
the following clinical
recommendations:
63. 1. Maximum conservation of tooth
structure
2. Custom-cast post and core for moderate
to severe tooth loss and non circular root
canals
3. Parallel sided, passive serrated, self-
venting prefabricated posts for small
circular canals
4. Posts with anti-rotational features in
circular canals
5. Adequate apical seal
6. More than one post for multi-rooted
short teeth
64. 7. When apical thickness of dentin is
minimum parallel tapered posts should
be used
8. Retentive qualities of post head may
facilitate firm retention of core
material
9. Ensure material compatibility,
bonding ability, adequate rigidity,
esthetic compatibility
10. Easy retrievability
65. Use a post system
that best fits the
individual needs of
each tooth
CONCLUSION
66. REFERENCE
S1. Contemporary fixed prosthisdontics. Rosensteil,
Land, Fujimoto.
2. Shillinburg HT, Hobo S, Whitsett L, Brackett S.
Fundamentals of fixed prosthdontics. 3rd
ed.
Chicago: Quintessence; 1997.
3. Nissan J, Dmitry Y, Assif D. The use of
reinforced composite resin cement as
compensation for reduced post length. J Prosthet
Dent 2001;86:304-8.
4. Akkayan B, Gulmez T. Resistance to fracture of
endodontically treated teeth restored with
different post systems. J Prosthet Dent
2002;87:431-7.
67. 5. Cohen BI, Pagnillo MK, Condos S, Deutsch
AS. Four different core materials measured for
fracture strength in combination with five
different designs of endodontic posts. J Prosthet
Dent 1996;76:487-95.
6. Stockton L. Factors affecting retention of
post system: a literature review. J Prosthet Dent
1999;81:380-
7.Cohen B1, Pagnillo MK, Newman I, Musikant
BL, Deutsch AS. Retention of a core material
supported by three post head designs. J Prosthet
Dent 2000;83:624-8.