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.

1. FACTORS DETERMINING POST
SELECTION
A LITERATURE REVIEW
Aquaviva Fernandes, Sharat Shetty, Ivy
Continho.
JPD 2003;90:556-62
Dr Talib Amin
GDC Srinagar

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

5. ENDODONTICALLY TREATED TEETH
WITH POST AND CORE HAVE GOOD
PROGNOSIS
 Serve well in function
 Act as an abutment in FPD or
RPD

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

7. DEFINITION

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

11. Tapered smooth posts
Tapered serrated posts
Tapered threaded posts
Parallel sided smooth posts
Parallel sided serrated
posts
Parallel sided threaded
posts
Combination
PREFABRICATED POSTS

12. CUSTOM MADE
 Direct pattern in patients
mouth
 Indirect pattern in
operatory

13. Pt- Au- Pd
Ni- Cr
Co- Cr
Stainless
steel
Au- Pt
Ni- Cr
Ti
Parallel sided
Tapered
METALLI
C

14. NON METALLIC
Carbon fiber
Glass fiber
Woven fiber (polyethen
Zirconia fiber
Ceramic fiber

15. This article is basically a
review of literature in which
various factors that
influence the selection of
post and core assembly are
mentioned.

16. BIOLOGICAL FACTORS
 Root length
 Tooth anatomy
 Root width
 Canal configuration
 Amount of coronal tooth structure

17. MECHANICAL
FACTORS
 Torquing forces
 Stresses
 Hydrostatic pressure
 Post design
 Post material
 Material compatibility
 Bonding capability
 Core retention

18. ESTHETIC
FACTORS

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

24. CONSERVATIONIST
APPROACH
 Minimal canal preparation
 Maintaining as much as
residual dentin as possible

25. PRESERVATIONIST
APPROACH
Post surrounded by
minimum of 1 mm of sound
dentin
( Halle,Nicholls, Hassel. J Endod
1984 )

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

40. Retention of posts
Threaded > serrated > smooth

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

55. DISCUSSION

56. Post & core contributes in
providing predictable
restorative options for
endodontically treated
teeth.

57. After reviewing the
literature, it appears that
an ideal post system
should have the
following features:

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.