• PRINCIPLES OF TOOTH
PREPARATION

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INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www.indiandentalacademy.com
• 1. CONSERVATION OF TOOTH
STRUCTURE

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• A) Preparation of the canal:
• When creating post space remove only
minimal tooth structure form canal.
• Excessive enl...
www.indiandentalacademy.com
• Pic of split root due to
post

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• The thickness of the remaining dentin is the
prime variable in fracture resistance of the
root.

www.indiandentalacademy...
????
• Hunter et al (JPD 1989:62;166) did a invitro
study and concluded that teeth with a
thicker post (1.8mm) fractured m...
• Fig of root M-d thin,
concavitites.
• Can show a cross
section of tooth.

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• B) Preparation of coronal tissue

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• Every effort should be made to save as
much of the coronal tooth structure as
possible, because this helps reduce stress...
??
• Stein RS et al (JPD 1002;68:428) in their
study concluded that if greater than 2mm of
coronal tooth structure remains...
Extending the preparation
apically
Creates a ferrule effect .

Extension of axial wall of the crown apical to
the missing ...
• Purpose of ferrule ( JPD 1990)
 improve the structural integrity of pulpless
tooth by counteracting
• 1. the functiona...
Extensively damaged teeth
• Crown lengthening
• Orthodontic extrusion

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• 2 Location where
ferrule can be given
• 1. Crown ferrule
ferrule created by the
overlying crown
engaging the tooth
stru...
• 2. core ferrule: ferrule
is a part of cast metal
core

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• Sorensen et al (JPD 1990:63;529) and Tjan
et al (JPD 1985;53:496)
• Ferrule formed as a part of core are less
effective ...
• Ferrules that grasp
larger amount of tooth
structure are more
effective than those
that engage only a
small amount of to...
• Libman et al (IJP 1995;8:155) found that 0.5-1
mm crown ferrule are ineffective , whereas 1.52mm crown ferrule is effect...
• Sloping ferrule

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• Sorensen at al
ferrules are more
effective when crown
encompasses
relatively parallel
prepared tooth
structure , than w...
RETENTION FORM

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ANTERIOR TEETH
•
•
•
•
•
•

Post retention is affected by the
preparation geometry,
post length,
diameter,
surface texture...
preparation geometry,
•

canals with circular cross
section( Max CI) 
prepare post space with
parallel walls.

• Tapered ...
FIG???
• Circular parallel posts are only effective in the
most apical portion of the post space because
majority of prepa...
Post Length

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Standlee et al ( JPD 1978;39:401)

Increase in
dowel length



But relation is not linear

www.indiandentalacademy.com

I...
Ideally post be as long as possible without
jeopardizing the apical seal
Or the strength or integrity
Of remaining tooth s...
If post too long
May damage apical seal
Risk of perforation if
apical third is curved or tapered

www.indiandentalacademy....
If post too short
increased chances of root fracture
(short post force applied near the incisal edge
Of the crown will ge...
Short root + tall clinical crown?
Post short compromised mechanics
Post long  compromised apical seal
3mm apical seal  ...
Post diameter
• Increase in post diameter to increase
retention not recommended. weaken
root.
• Prognosis good when post...
Post surface texture

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Serrated surface

> Smooth surface

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Threaded dowel >

Smooth dowel

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Luting agents

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• Resin cements> GIC = zinc phosphate>poly
carboxylate.

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• Choice of cement more important if post
has poor fit in canal.
• If rotation or post wobbles remake
• Resin cements  i...
• Resin cements affected by eugenol
containing RC sealers
• Eugenol contains 2-methoxy- 4-allyphenol
inhibits polymerizati...
Anthony H.L. Tjan et al (Q Int.
1992;23:839)
• Did a study to evaluate the effect of
eugenol- containing endodontic sealer...
Irrigating the post space with alcohol
or etching with phosphoric acid gel
effectively restored the retention.
• The use o...
Posterior teeth
• Long post with circular cross section 
avoided curved, elliptical or ribbon
shaped roots perforation....
Chances of perforation on distal surface of mesial root
And mesial surface of distal root

www.indiandentalacademy.com
• Retention better by 2 or
more relatively short posts
in divergent canals
• Select canals that are
widest( palatal-max,
d...
www.indiandentalacademy.com
Resistance form

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• Rotational resistance

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• Circular post should not
rotate during function.
• Sufficient tooth structure
present vertical coronal
wall prevents ro...
www.indiandentalacademy.com
• Kurer et al (JPD
1977;38;515)
• Gave a method to prevent
rotation of threaded posts
by placing rotation lock.
• Sig: pla...
Stress distribution
• Post and core improves resistance to
laterally directed forces by distributing
them over a large are...
• Increase in post length decrease stresses.
• Parallel sided post more even stress distribution
than tapered post (wedg...
Basic components used in
restoration of endodontically
treated tooth

www.indiandentalacademy.com
• Restorations for endodontically treated
teeth are designed to :
• Protect remaining tooth from fracturing
• To replace m...
• The final restoration will include a
combination of:
• 1. Dowel,
• 2. core
• 3. coronal restoration

www.indiandentalaca...
Find a better pic
•
•

•

Core: replaces lost coronal;
tooth structure and provides
retention for crown
Dowel: provides re...
• The selection of individual components will
depend on
• whether the tooth is anterior or posterior
• or whether signific...
• DOWEL

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• dowel : a post, usually made of metal that is
fitted into a prepared root canal of a natural
tooth. When combined with a...
• the dowel has both a retentive and protective
function:
• primarily to aid in the retention of the restoration
and
• to ...
•
•
•
•
•
•
•
•

Ideal properties of the dowel.
Maximum protection of the root
Adequate retention within the root
Maximum ...
• CLASSIFICATION OF DOWELS

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•
•
•
•

By Stephen Cohen
Preformed dowels and custom cast dowels
Metallic and non metallic dowels
Rigid and flexible dowe...
•
•
•
•

By Ricketts et al ( BDJ 2005;198: 533)
1 . Active Posts
A. Pre tapped posts
B. Self threading

•
•
•
•

2.Passive...
•
•
•
•
•

III
A.
B
C.
D.

Wein's Classification
Tapered smooth sided
Parallel, serrated and vented posts
Parallel threade...
give examples??
•
•
•
•
•
•
•
•

Acc To Rosensteil
Prefabricated post
Tapered smooth sided posts
Tapered serrated posts
Ta...
•
•
•
•
•
•
•
•
•
•
•
•
•

Acc to material used
Wooden posts
Type III and Type IV gold alloy
Stainless steel
Gold Platinum...
Retentive, Protective and
Esthetic qualities of
dowels

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Retentive qualities:
• Dowel-to-root retention and
• Dowel-to-core retention.

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Dowel retention varies with
• dowel design,
• dowel composition and
• cement type.

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Dowel design and dowel retention

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a) Dowel to root retention

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Parallel sided

>

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Tapered
Serrated surface

> Smooth surface

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Purton et al (IJP 1996;9:484)
Effect of serrations on carbon fiber
post retention within the root canal.

www.indiandental...
Increase in
dowel length



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Increased
retention
Threaded dowel >

Smooth dowel

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• Variousdiameters for tooth ??? From
rosensteil

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Dowel diameter
Increase in post diameter to increase
retention not recommended. weaken
root.

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b) Dowel to core retention

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One piece dowel
and core

>

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Dowel with
locking feature
Large dowel head

>

Smaller dowel head

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Dowel Composition and Dowel
Retention

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• Dowel retention is a clinical quality that is
related to the underlying physical properties
of the dowel material. The i...
• Metal dowels are more fracture resistant 
more retentive than carbon fiber dowel

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???
• Carbon fiber and glass fiberretained by
dentine bonding agents better retention

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Core retention
• The composition of the dowel also affects
the ability to retain the core.

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• Integrated dowel and
core systems in which
both the dowel and the
core are formed
simultaneously from
the same material
...
• Dowel cementation and dowel retention.

• Retention for all types of dowels is
affected by the cement selec­tion.

www.i...
• zinc phosphate
• retention  mechanical means.
• no chemical bond to

dowel
or dentin
• lack of chemical bond  advantag...
• Glass ionomer cements
• bonds to dentin
• but not to dowel

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• Resin cements examples?????
• bonds to dentin
• and most dowel materials

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• Standlee et al (JPD 1992:68;913) did a study on
dowels retained by resin cements and concluded
these dowels achieved ver...
• Cement manipulation procedures and ease
of use  affect clinical retention of
cements to the dowel.

• Cement flow prope...
• strength and retention of resin cements also
depends on complete set­ting.

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• Protective qualities of dowels
• (resistance to root fracture )

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• The dowel must furnish maximum
resistance to root fracture while providing
reten­tion between the root and the core.

ww...
• Dowel design and resistance to root
fracture
• Dowel shape and resistance to root
fracture

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• Parallel metal dowels distribute func­tional
loads to the root more passively than
tapered dowels.

www.indiandentalacad...
• Isidor et al (IJP 1992;5:257)
• Martinez et al( JPD 1998;80;527)
• tapered dowels (including the custom­cast
dowel and c...
• Self threading dowels high rates of root
fracture
• Standlee et al (JPD 1992:68;913)
• 40% of Self threading dowels fai...
??
• About fiber dowels>>>>> less fracture of
roos?????????????

www.indiandentalacademy.com
• Dowel diameter and resistance to root fracture
•
• Sufficient to resist distortion and permanent
bending under functiona...
• Dowel length’ and resistance to root fracture

• Long enough to reduce conc. Of force in areas embedded
in alveolar bone...
• Dowel composition and resistance to root
fracture
• Metal and zirconia dowels stiffer than
dentinemore force conc. On ...
ESTHETIC QUALITIES OF
DOWEL
• Metal and carbon fiber dowels non esthetic
not to be used in esthetically critical areas ....
• ESTHETIC POST SYSTEMS

www.indiandentalacademy.com
Carbon fiber post
(composipost(bisco)…), C­
post(bisco) fig

• Introduced in 1990 by Duret .
• First non metallic post

• ...
•
•
•

•

Advantage:
Clinical procedures are less time consuming
The modulus of elasticity of the metal post is ten times ...
• Disadvantage
• Black colou­unesthetic
• Radiolucency­very difficult to detect
radiographically.
• Undergo degradation on...
• Some studies??????

www.indiandentalacademy.com
Ceramic posts
• have excellent esthetics and biological properties
• . Inherent weaknesses  low flexural strength and low...
•
•
•
•

Advantages
Good esthetics
Biocompatible
Other esthetic post systems lack strength,
Ceramic post are esthetic alte...
• Disadvantages
• High chances of root fracture
• ?

• Trade names
• Cosmo post( Vivadent), Snow post (Danville?)??
• Biop...
• Glass fiber post
• Unidirectional glass fibers embedded in a
resin matrix

www.indiandentalacademy.com
• Quartz fiber post(RTD post)

www.indiandentalacademy.com
•
•
•
•

Advantage:
Modulus of elasticity close to dentine
Esthetic
Made of resinbond strength of resin
cement enhanced.
...
• Disadvantage:
• Variable opacity
• Undergo degradation on repeated
mechanical loading and moisture
contamination reduce...
Polyethylene woven fiber
(Ribbond)
• Suggested for use with composite to
fabricate dowel and core.

www.indiandentalacadem...
• Intraradicular Rehabilitation
• Extensive decay or aggressive
instrumentation of the canal makes the
canal too wide for ...
•
•
•
•
•
•

I. Luminex Light Transmitting
System( Dentatus)
The Light-Transmitting Technology
for restoring Structurally
...
•
•

Lucent Anchor system (Dentatus)
Fiber glass clear resin post

•

designed to refract and transmit natural tooth
color...
• Twin Luscent Anchors(Dentatus)

www.indiandentalacademy.com
Anchor Design
Element

Benefit

Twin Luscent Anchor

Narrow radial
midsection

Mechanica
l
resistance

Provides double ret...
Shape Matches
Root Form
•Twin Luscent and
Luscent Anchors
completely fit
within the confines
of natural teeth
•Anchor desi...
• II. Para Post Fiber White Post :
• The Para post fiber white post is a filled resin mono
directional fiber matrix with a...
• III. FibreKor Post:
• The FibreKor post uses glass fibers bundled in a resin
matrix. The bundles are in turn impregnated...
• IV. Aesthetic-Plus Post:
• The aesthetic­post system is actually a series of
that can be used in a variety of situations...
D.T. LIGHT-POST (Bisco)
•
•

•

constructed from unidirectional, pre­tensed, quartz
fibers bound in a resin matrix
produce...
ÆSTHETI-PLUSTM (2-Stage)
Aesthetic Fiber Post System
Bisco

• These posts can be
used with light­cured
or dual­cured
adhes...
•
•
•
•
•
•
•
•
•

ParaPost fiber white (coltene
whaledent)
Glass Fiber 42%

White, translucent color minimizes the
possib...
•

ÆSTHETI­POST® Carbon/Quartz

•
•
•

FibreKor® Glass
Cosmopost™ Zirconium
Seventeen different FRC posts of various brand...
• In vitro comparison of the fracture resistance and
failure mode of fiber, ceramic, and conventional post
systems at vari...
•
•

AESTHETI­PLUS
Quartz Fibers : 60 % volume
Epoxy Resin : 40 % volume

•

AESTHETI­POSTCarbon Fiber Core: 10 % volume
Q...
•

RTD Fibre Posts

•

Features of RTD Fibre posts
- Strongest of all the fibre posts in
existence (surviving where others...
•

Double Tapered (DT) Light Post
The new double taper posts that
matches canal walls.
­ 4 times stronger than steel
­ Too...
•

The Original Light Post
The Light Post is the latest
evolution of the Composipost.
The Light Post's translucency
means ...
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Thank you
www.indiandentalacademy.com
Leader in continuing dental education

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Principles of tooth preparation /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.


Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
00919248678078

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Principles of tooth preparation /certified fixed orthodontic courses by Indian dental academy

  1. 1. • PRINCIPLES OF TOOTH PREPARATION www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3. • 1. CONSERVATION OF TOOTH STRUCTURE www.indiandentalacademy.com
  4. 4. • A) Preparation of the canal: • When creating post space remove only minimal tooth structure form canal. • Excessive enlargement can: • Perforate • Weaken the root tooth may split during cementation of post or during subsequent function. www.indiandentalacademy.com
  5. 5. www.indiandentalacademy.com
  6. 6. • Pic of split root due to post www.indiandentalacademy.com
  7. 7. • The thickness of the remaining dentin is the prime variable in fracture resistance of the root. www.indiandentalacademy.com
  8. 8. ???? • Hunter et al (JPD 1989:62;166) did a invitro study and concluded that teeth with a thicker post (1.8mm) fractured more easily than those with a thinner one( 1.3mm) www.indiandentalacademy.com
  9. 9. • Fig of root M-d thin, concavitites. • Can show a cross section of tooth. www.indiandentalacademy.com
  10. 10. • B) Preparation of coronal tissue www.indiandentalacademy.com
  11. 11. • Every effort should be made to save as much of the coronal tooth structure as possible, because this helps reduce stress concentrations at the gingival margin.1" www.indiandentalacademy.com
  12. 12. ?? • Stein RS et al (JPD 1002;68:428) in their study concluded that if greater than 2mm of coronal tooth structure remains the post design probably has a limited role in fracture resistance of restored tooth. www.indiandentalacademy.com
  13. 13. Extending the preparation apically Creates a ferrule effect . Extension of axial wall of the crown apical to the missing tooth structure Provides a ferrule. www.indiandentalacademy.com
  14. 14. • Purpose of ferrule ( JPD 1990)  improve the structural integrity of pulpless tooth by counteracting • 1. the functional lever forces • 2. the wedging effect of tapered dowels • 3. the lateral forces exerted during insertion of dowel • Thus prevents root fracture. www.indiandentalacademy.com
  15. 15. Extensively damaged teeth • Crown lengthening • Orthodontic extrusion www.indiandentalacademy.com
  16. 16. • 2 Location where ferrule can be given • 1. Crown ferrule ferrule created by the overlying crown engaging the tooth structure www.indiandentalacademy.com
  17. 17. • 2. core ferrule: ferrule is a part of cast metal core www.indiandentalacademy.com
  18. 18. • Sorensen et al (JPD 1990:63;529) and Tjan et al (JPD 1985;53:496) • Ferrule formed as a part of core are less effective than ferrule as a part of crown • Ferrule effect at both the levels did not increase fracture resistance as compared to ferrule only at crown level. www.indiandentalacademy.com
  19. 19. • Ferrules that grasp larger amount of tooth structure are more effective than those that engage only a small amount of tooth structure. www.indiandentalacademy.com
  20. 20. • Libman et al (IJP 1995;8:155) found that 0.5-1 mm crown ferrule are ineffective , whereas 1.52mm crown ferrule is effective. • Isidor et al (IJP 1999;12:78) increasing crown ferrule length  increases fracture resistance (1.25 & 1.55 mm) • Concluded  ferrule length was more important • Than post length in increasing tooth’s fracture resistance.( ideal 2mm???) www.indiandentalacademy.com
  21. 21. • Sloping ferrule www.indiandentalacademy.com
  22. 22. • Sorensen at al ferrules are more effective when crown encompasses relatively parallel prepared tooth structure , than when it engages sloping tooth structure. www.indiandentalacademy.com
  23. 23. RETENTION FORM www.indiandentalacademy.com
  24. 24. ANTERIOR TEETH • • • • • • Post retention is affected by the preparation geometry, post length, diameter, surface texture, and by the Luting agent www.indiandentalacademy.com
  25. 25. preparation geometry, • canals with circular cross section( Max CI)  prepare post space with parallel walls. • Tapered canals if parallel sided post given canal has to be considerably enlarged weakening of root. • Tepared post with restricted amount of taper( 6-8 degrees) www.indiandentalacademy.com
  26. 26. FIG??? • Circular parallel posts are only effective in the most apical portion of the post space because majority of prepared post spaces demonstrate considerable flare in the occlusal half. www.indiandentalacademy.com
  27. 27. Post Length www.indiandentalacademy.com
  28. 28. Standlee et al ( JPD 1978;39:401) Increase in dowel length  But relation is not linear www.indiandentalacademy.com Increased retention
  29. 29. Ideally post be as long as possible without jeopardizing the apical seal Or the strength or integrity Of remaining tooth structure. 5mm of GP be left in apical area www.indiandentalacademy.com
  30. 30. If post too long May damage apical seal Risk of perforation if apical third is curved or tapered www.indiandentalacademy.com
  31. 31. If post too short increased chances of root fracture (short post force applied near the incisal edge Of the crown will generate a greater couple increased possibility of root fracture Decreased retention www.indiandentalacademy.com
  32. 32. Short root + tall clinical crown? Post short compromised mechanics Post long  compromised apical seal 3mm apical seal  acceptable www.indiandentalacademy.com
  33. 33. Post diameter • Increase in post diameter to increase retention not recommended. weaken root. • Prognosis good when post diameter < 1/3 rd of cross sectional diameter of the root www.indiandentalacademy.com
  34. 34. Post surface texture www.indiandentalacademy.com
  35. 35. Serrated surface > Smooth surface www.indiandentalacademy.com
  36. 36. Threaded dowel > Smooth dowel www.indiandentalacademy.com
  37. 37. Luting agents www.indiandentalacademy.com
  38. 38. • Resin cements> GIC = zinc phosphate>poly carboxylate. www.indiandentalacademy.com
  39. 39. • Choice of cement more important if post has poor fit in canal. • If rotation or post wobbles remake • Resin cements  if post is dislodged and has to be recemented. www.indiandentalacademy.com
  40. 40. • Resin cements affected by eugenol containing RC sealers • Eugenol contains 2-methoxy- 4-allyphenol inhibits polymerization of composites. www.indiandentalacademy.com
  41. 41. Anthony H.L. Tjan et al (Q Int. 1992;23:839) • Did a study to evaluate the effect of eugenol- containing endodontic sealer on retention of prefabricated pots luted with adhesive composite resin cement. They concluded that: • Eugenol significantly reduced the retention of parapost dowels luted with panavia composite resin cement. www.indiandentalacademy.com
  42. 42. Irrigating the post space with alcohol or etching with phosphoric acid gel effectively restored the retention. • The use of alcohol (ehtyl alcohol/ethanol) as a canal irrigant or etching with 37% phosphoric acid gel was found to be effective in restoring the resistance to dislodgement of post. Irrigation with alcohol produced a more consistant and reliable result. www.indiandentalacademy.com
  43. 43. Posterior teeth • Long post with circular cross section  avoided curved, elliptical or ribbon shaped roots perforation. • . www.indiandentalacademy.com
  44. 44. Chances of perforation on distal surface of mesial root And mesial surface of distal root www.indiandentalacademy.com
  45. 45. • Retention better by 2 or more relatively short posts in divergent canals • Select canals that are widest( palatal-max, distal-mandibular) for major post and then prepare short auxiliary post space in other canal with same path of withdrawl www.indiandentalacademy.com
  46. 46. www.indiandentalacademy.com
  47. 47. Resistance form www.indiandentalacademy.com
  48. 48. • Rotational resistance www.indiandentalacademy.com
  49. 49. • Circular post should not rotate during function. • Sufficient tooth structure present vertical coronal wall prevents rotation • Coronal dentine lost small groove anti rotational element www.indiandentalacademy.com
  50. 50. www.indiandentalacademy.com
  51. 51. • Kurer et al (JPD 1977;38;515) • Gave a method to prevent rotation of threaded posts by placing rotation lock. • Sig: placement of post without cement possible facilitates removal of dowel in needed. www.indiandentalacademy.com
  52. 52. Stress distribution • Post and core improves resistance to laterally directed forces by distributing them over a large area. • Post design should distribute stresses as evenly as possible. www.indiandentalacademy.com
  53. 53. • Increase in post length decrease stresses. • Parallel sided post more even stress distribution than tapered post (wedging effect). But Parallel sided post generate more stress at apex. • Threaded post high stress conc during insertion and loading. • High stress during insertion of smooth parallel sided posts as no place for escape for cement. • Cement layer more even stress distribution. www.indiandentalacademy.com
  54. 54. Basic components used in restoration of endodontically treated tooth www.indiandentalacademy.com
  55. 55. • Restorations for endodontically treated teeth are designed to : • Protect remaining tooth from fracturing • To replace missing tooth structure www.indiandentalacademy.com
  56. 56. • The final restoration will include a combination of: • 1. Dowel, • 2. core • 3. coronal restoration www.indiandentalacademy.com
  57. 57. Find a better pic • • • Core: replaces lost coronal; tooth structure and provides retention for crown Dowel: provides retention for core and must be designed to decrease the potential for root fracture from functional forces. Crown: restores the function and esthetics and protects the remaining root and coronal structure from fracture. www.indiandentalacademy.com
  58. 58. • The selection of individual components will depend on • whether the tooth is anterior or posterior • or whether significant coronal tooth structure is missing. www.indiandentalacademy.com
  59. 59. • DOWEL www.indiandentalacademy.com
  60. 60. • dowel : a post, usually made of metal that is fitted into a prepared root canal of a natural tooth. When combined with an artificial crown or core, it provides retention and resistance for the .restoration (GPT-7) www.indiandentalacademy.com
  61. 61. • the dowel has both a retentive and protective function: • primarily to aid in the retention of the restoration and • to protect the tooth by dissipating or disbursing forces along the length of the root. • The dowel itself does not strengthen a tooth. infact the tooth is weakened if dentin is sacrificed to place a large diameter dowel. www.indiandentalacademy.com
  62. 62. • • • • • • • • Ideal properties of the dowel. Maximum protection of the root Adequate retention within the root Maximum retention of the core and crown Pleasing esthetics, when indicated High radiographic visibility Retrievability Biocompatibility www.indiandentalacademy.com
  63. 63. • CLASSIFICATION OF DOWELS www.indiandentalacademy.com
  64. 64. • • • • By Stephen Cohen Preformed dowels and custom cast dowels Metallic and non metallic dowels Rigid and flexible dowels Aesthetic and nonesthetic dowels www.indiandentalacademy.com
  65. 65. • • • • By Ricketts et al ( BDJ 2005;198: 533) 1 . Active Posts A. Pre tapped posts B. Self threading • • • • 2.Passive Posts A. Custom made or prefabricated B. Parallel smooth or serrated C.. Tapered smooth or serrated www.indiandentalacademy.com
  66. 66. • • • • • III A. B C. D. Wein's Classification Tapered smooth sided Parallel, serrated and vented posts Parallel threaded posts Parallel threaded split shank posts. www.indiandentalacademy.com
  67. 67. give examples?? • • • • • • • • Acc To Rosensteil Prefabricated post Tapered smooth sided posts Tapered serrated posts Tapered Threaded posts Parallel smooth sided Parallel serrated posts Parallel Threaded posts • • • Custom made post Direct technique Indirect technique www.indiandentalacademy.com
  68. 68. • • • • • • • • • • • • • Acc to material used Wooden posts Type III and Type IV gold alloy Stainless steel Gold Platinum alloy Titanium/ Titanium alloy Brass Nickel chromium and Cobalt chromium Cobalt chromium molybdenum alloy Amalgam Carbon fiber Glass fiber Ceramic Posts, Zirconium dioxide post www.indiandentalacademy.com
  69. 69. Retentive, Protective and Esthetic qualities of dowels www.indiandentalacademy.com
  70. 70. Retentive qualities: • Dowel-to-root retention and • Dowel-to-core retention. www.indiandentalacademy.com
  71. 71. Dowel retention varies with • dowel design, • dowel composition and • cement type. www.indiandentalacademy.com
  72. 72. Dowel design and dowel retention www.indiandentalacademy.com
  73. 73. a) Dowel to root retention www.indiandentalacademy.com
  74. 74. Parallel sided > www.indiandentalacademy.com Tapered
  75. 75. Serrated surface > Smooth surface www.indiandentalacademy.com
  76. 76. Purton et al (IJP 1996;9:484) Effect of serrations on carbon fiber post retention within the root canal. www.indiandentalacademy.com
  77. 77. Increase in dowel length  www.indiandentalacademy.com Increased retention
  78. 78. Threaded dowel > Smooth dowel www.indiandentalacademy.com
  79. 79. • Variousdiameters for tooth ??? From rosensteil www.indiandentalacademy.com
  80. 80. Dowel diameter Increase in post diameter to increase retention not recommended. weaken root. www.indiandentalacademy.com
  81. 81. b) Dowel to core retention www.indiandentalacademy.com
  82. 82. One piece dowel and core > www.indiandentalacademy.com Dowel with locking feature
  83. 83. Large dowel head > Smaller dowel head www.indiandentalacademy.com
  84. 84. Dowel Composition and Dowel Retention www.indiandentalacademy.com
  85. 85. • Dowel retention is a clinical quality that is related to the underlying physical properties of the dowel material. The inherent strength of the dowel affects the dowel retention to the root and to the core. www.indiandentalacademy.com
  86. 86. • Metal dowels are more fracture resistant  more retentive than carbon fiber dowel www.indiandentalacademy.com
  87. 87. ??? • Carbon fiber and glass fiberretained by dentine bonding agents better retention www.indiandentalacademy.com
  88. 88. Core retention • The composition of the dowel also affects the ability to retain the core. www.indiandentalacademy.com
  89. 89. • Integrated dowel and core systems in which both the dowel and the core are formed simultaneously from the same material eliminate the dowel and core interface. www.indiandentalacademy.com
  90. 90. • Dowel cementation and dowel retention. • Retention for all types of dowels is affected by the cement selec­tion. www.indiandentalacademy.com
  91. 91. • zinc phosphate • retention  mechanical means. • no chemical bond to dowel or dentin • lack of chemical bond  advantageous www.indiandentalacademy.com
  92. 92. • Glass ionomer cements • bonds to dentin • but not to dowel www.indiandentalacademy.com
  93. 93. • Resin cements examples????? • bonds to dentin • and most dowel materials www.indiandentalacademy.com
  94. 94. • Standlee et al (JPD 1992:68;913) did a study on dowels retained by resin cements and concluded these dowels achieved very high retention. • Parallel dowels cemented with an adhesive cement are equal in retention to screw type dowels, without the inherent risk of screw threads in dentine. • This cement mediated maximum retention is not risk free, as 80% of the roots fractured when dowels were dislodged by force. www.indiandentalacademy.com
  95. 95. • Cement manipulation procedures and ease of use  affect clinical retention of cements to the dowel. • Cement flow properties and consistency www.indiandentalacademy.com
  96. 96. • strength and retention of resin cements also depends on complete set­ting. www.indiandentalacademy.com
  97. 97. • Protective qualities of dowels • (resistance to root fracture ) www.indiandentalacademy.com
  98. 98. • The dowel must furnish maximum resistance to root fracture while providing reten­tion between the root and the core. www.indiandentalacademy.com
  99. 99. • Dowel design and resistance to root fracture • Dowel shape and resistance to root fracture www.indiandentalacademy.com
  100. 100. • Parallel metal dowels distribute func­tional loads to the root more passively than tapered dowels. www.indiandentalacademy.com
  101. 101. • Isidor et al (IJP 1992;5:257) • Martinez et al( JPD 1998;80;527) • tapered dowels (including the custom­cast dowel and core) that are closely adapted to the internal shape of the root canal are more likely to result in root fracture than are parallel­sided dowels. www.indiandentalacademy.com
  102. 102. • Self threading dowels high rates of root fracture • Standlee et al (JPD 1992:68;913) • 40% of Self threading dowels failed by angular and vertical root fracture. www.indiandentalacademy.com
  103. 103. ?? • About fiber dowels>>>>> less fracture of roos????????????? www.indiandentalacademy.com
  104. 104. • Dowel diameter and resistance to root fracture • • Sufficient to resist distortion and permanent bending under functional forces • Large risk of fracture • Composition plays a role parallel metal dowels narrower diameter than nonmetallic dowelspreserve tooth structure. www.indiandentalacademy.com
  105. 105. • Dowel length’ and resistance to root fracture • Long enough to reduce conc. Of force in areas embedded in alveolar bone. • Isidor F et al (IJP 1999;12:78)  increasing dowel length from 5mm to 10 mm did not increased the fracture resistance in teeth protected by crowns designed with adequate ferrule. www.indiandentalacademy.com
  106. 106. • Dowel composition and resistance to root fracture • Metal and zirconia dowels stiffer than dentinemore force conc. On root high chance of root fracture • Carbon fibre, glass fibre etcphysical properties resemble those of dentineless force conc on root (stress dissipated better) les chances of root fracture. www.indiandentalacademy.com
  107. 107. ESTHETIC QUALITIES OF DOWEL • Metal and carbon fiber dowels non esthetic not to be used in esthetically critical areas . • Zirconia, fiberglas etc esthetic • Zirconia stiffer than dentine esthetic equivalent to preformed metal dowels.(fig??) www.indiandentalacademy.com
  108. 108. • ESTHETIC POST SYSTEMS www.indiandentalacademy.com
  109. 109. Carbon fiber post (composipost(bisco)…), C­ post(bisco) fig • Introduced in 1990 by Duret . • First non metallic post • Consist of bundles of stretched carbon fibers embedded in an epoxy resin matrix and aligned along the long axis of post. • Unidirectional fibers, 8 microns in diameter • Carbon fiber by exerting uniform tension on the filaments impart high strength to the posts. www.indiandentalacademy.com
  110. 110. • • • • Advantage: Clinical procedures are less time consuming The modulus of elasticity of the metal post is ten times greater than that of dentin. This incompatibility creates stress at the tooth cement post interface occasionally causing post separation and failure. Additionally the transmission of occlusal and lateral forces through the metallic core can focus stresses at specific areas of the most anatomy such as fulcrum resulting in fracture of remaining dentinal structure. The carbon fibers have modulus of elasticity very similar to dentin, this resemblance eliminates the stresses that are often formed at the interface of different material. Easy to remove for retreatment. www.indiandentalacademy.com
  111. 111. • Disadvantage • Black colou­unesthetic • Radiolucency­very difficult to detect radiographically. • Undergo degradation on repeated mechanical loading and moisture contamination reduced modulus of elasticityrisk of debonding.. www.indiandentalacademy.com
  112. 112. • Some studies?????? www.indiandentalacademy.com
  113. 113. Ceramic posts • have excellent esthetics and biological properties • . Inherent weaknesses  low flexural strength and low tensile strength prone to fracture. • New ceramics like pressable ceramics, infiltrated ceramics,and zirconia can be used. • Zirconia posts high flexural strength and tensile strength. • Made from fined grained tetragonal Zirconium polycrystals (TZP). www.indiandentalacademy.com
  114. 114. • • • • Advantages Good esthetics Biocompatible Other esthetic post systems lack strength, Ceramic post are esthetic alternative to metal posts. www.indiandentalacademy.com
  115. 115. • Disadvantages • High chances of root fracture • ? • Trade names • Cosmo post( Vivadent), Snow post (Danville?)?? • Biopost, TPZ post IPS Empress® Cosmo www.indiandentalacademy.com
  116. 116. • Glass fiber post • Unidirectional glass fibers embedded in a resin matrix www.indiandentalacademy.com
  117. 117. • Quartz fiber post(RTD post) www.indiandentalacademy.com
  118. 118. • • • • Advantage: Modulus of elasticity close to dentine Esthetic Made of resinbond strength of resin cement enhanced. www.indiandentalacademy.com
  119. 119. • Disadvantage: • Variable opacity • Undergo degradation on repeated mechanical loading and moisture contamination reduced modulus of elasticityrisk of debonding.. www.indiandentalacademy.com
  120. 120. Polyethylene woven fiber (Ribbond) • Suggested for use with composite to fabricate dowel and core. www.indiandentalacademy.com
  121. 121. • Intraradicular Rehabilitation • Extensive decay or aggressive instrumentation of the canal makes the canal too wide for direct restoration. It is difficult to position the post in an ideal location for the subse­quent restoration www.indiandentalacademy.com
  122. 122. • • • • • • I. Luminex Light Transmitting System( Dentatus) The Light-Transmitting Technology for restoring Structurally Compromised Teeth Fragile, thin­walled teeth Extraction or cast post Now luminex system The clear light transmitting posts polymerize light­cured composites within the entire root canal. Luminex light transmitting post (LTP) allows the passage of light through its body but does not bond to the composite resin.. After curing, the LUMINEX post is removed, leaving a ready canal for a corresponding metal post. www.indiandentalacademy.com
  123. 123. • • Lucent Anchor system (Dentatus) Fiber glass clear resin post • designed to refract and transmit natural tooth colors for esthetic post and core foundation. • A benefit of the translucent anchor is that it can be used with dual-cure resins and bonding techniques, which allow sufficient time for exact centering and seating of the anchor, as well as a complete fill of the composite inside the canal ( • radiolucent and is identified by surrounding resin cement. • • luted to the post space by dual cure resin. easy to remove for re­access to the canals. www.indiandentalacademy.com
  124. 124. • Twin Luscent Anchors(Dentatus) www.indiandentalacademy.com
  125. 125. Anchor Design Element Benefit Twin Luscent Anchor Narrow radial midsection Mechanica l resistance Provides double retention against accidental debonding of resins and other restorative materials Easy release Eliminates hydro­static of excess •Optimal choice for very pressure narrow and small canals, resin from 0.8 mm to 1.2mm Original Luscent Anchor •True taper Longitudinal www.indiandentalacademy.com vent-grove
  126. 126. Shape Matches Root Form •Twin Luscent and Luscent Anchors completely fit within the confines of natural teeth •Anchor design is Twin Luscent tapered apically to match root form, www.indiandentalacademy.com minimizing apical seal CEJ Luscent
  127. 127. • II. Para Post Fiber White Post : • The Para post fiber white post is a filled resin mono directional fiber matrix with a flexural modulus that very closely approximates that of the natural dentin. The color of the post is white translucent, designed to minimize shadowing under all ceramic restorations. The parallel sided posts intended for passive seating in the canal, and the antirotation I post head stabilizes the core materials. The Parapost fibre which is available in four diameters, color coded to match drills. The posts are readily removed should endodontic retreatment be necessary. www.indiandentalacademy.com
  128. 128. • III. FibreKor Post: • The FibreKor post uses glass fibers bundled in a resin matrix. The bundles are in turn impregnated with resin, cured and precision milled. The white color of the post blends in readily with dentin, eliminating the halo affect of metal or carbon fiber posts underneath all­ceramic restorations. The modulus of elasticity of the FibreKor post is closely matched to that of dentin, helping to distribute impact forces more uniformly along the prepared canal interface. The post is available in three diameters with size­matched drills. www.indiandentalacademy.com
  129. 129. • IV. Aesthetic-Plus Post: • The aesthetic­post system is actually a series of that can be used in a variety of situations. The traditional posts are two stage fiber posts, available in white or clear quartz fibers. There is also a tapered white fiber post. The posts have characteristics that are similar to their carbon fiber ancestors, including high flexural strength and a low modulus of elasticity. All the posts are retrievable if required for endodontic retreatment. www.indiandentalacademy.com
  130. 130. D.T. LIGHT-POST (Bisco) • • • constructed from unidirectional, pre­tensed, quartz fibers bound in a resin matrix produces a post with flexural strength exceeding that of metal posts but with a modulus of elasticity very close to that of dentin. dissipates stress rather than transferring and concentrating stress in the residual root structures Because of its translucency, BISCO's D.T. Light­ Posts will transmit light and can be used with light­ cured or dual­cured cements and adhesives. • This post will intimately bond to the tooth structure and core build­up composite • This post is OPTICALLY TRANSLUCENT and RADIOPAQUE, at the same time. Each of the 3 sizes has an apical taper 0.02 (increase of diameter/millimeter), middle taper of 0.06, 0.08 and 0.10, and a parallel coronal section for maximum strength, surface area and core retention. • • • • • www.indiandentalacademy.com
  131. 131. ÆSTHETI-PLUSTM (2-Stage) Aesthetic Fiber Post System Bisco • These posts can be used with light­cured or dual­cured adhesives. www.indiandentalacademy.com
  132. 132. • • • • • • • • • ParaPost fiber white (coltene whaledent) Glass Fiber 42% White, translucent color minimizes the possibility of shadowing in anterior restorations. Metal­free for esthetics and for patients with metal allergies. Flexural modulus measures closer to dentin than other post materials. Filled resin/uni­directional fiber matrix strengthens the structure of the post without. compromising flexibility. Passive, parallel­sided design mirrors the qualities of metal ParaPostÆs. Anti­rotational post head for excellent adaptation of core material. Specially fabricated to bond with most resin cements and core materials. Readily removed if endodontic re­treatment becomes necessary. The posts are color coded for use with existing ParaPostÆ drills. www.indiandentalacademy.com
  133. 133. • ÆSTHETI­POST® Carbon/Quartz • • • FibreKor® Glass Cosmopost™ Zirconium Seventeen different FRC posts of various brands (Snowpost, Carbopost, Parapost, C­ post, Glassix, Carbonite) • C­POST (Bisco); G2: ÆSTHETI­POST (Bisco); G3: ÆSTHETI­PLUS (Bisco); G4: LIGHT­POST (Bisco); G5: D.T. LIGHT­POST (Bisco); G6: PARAPOST WHITE (Coltene); G7: FIBERKOR (Pentron); G8: REFORPOST (Angelus). • Snowpost (yellow) Unidirectional Silica­zirconium fiber (60 vol%) Carbotech, Ganges, France 1.2 • 2 Snowpost (red) Unidirectional Silica­zirconium fiber (60 vol% www.indiandentalacademy.com
  134. 134. • In vitro comparison of the fracture resistance and failure mode of fiber, ceramic, and conventional post systems at various stages of restoration • J Prosthodont. 2001 Mar;10(1):26­36 • The fiber posts evaluated provided an advantage over a conventional post that showed a higher number of irretrievable post and unrestorable root fractures. At the stage of final restoration insertion, there was no difference in force to failure for all but the FibreKor material, which continued to be weaker than all other tested materials. The fiber posts were readily retrievable after failure, whereas the remaining post systems tested were nonretrievable. www.indiandentalacademy.com
  135. 135. • • AESTHETI­PLUS Quartz Fibers : 60 % volume Epoxy Resin : 40 % volume • AESTHETI­POSTCarbon Fiber Core: 10 % volume Quartz Fiber Coating : 50 % volume Epoxy Resin : 40 % volume • COMPOSIPOST/C­POSTCarbon Fibers : 64 % volume Epoxy Resin : 36 % volume • D.T. LIGHT­POSTQuartz Fibers : 60 % volume Epoxy Resin : 40 % volume www.indiandentalacademy.com
  136. 136. • RTD Fibre Posts • Features of RTD Fibre posts - Strongest of all the fibre posts in existence (surviving where others fail) - 4 times stronger than steel - Post & Core formed in one office visit - Integrates with & reinforces tooth - Does not split roots - Absorbs & Dissipates stress - Widely researched & study supported - Flexes with tooth - Fatigue resistant - Corrosion resistant, bonds with resin cement - Readily removable with re-access kit Added advantages of Light Post - Fibreoptic / light transmiting - Translucent - Aesthetic - Ideal for an all ceramic restoration www.indiandentalacademy.com
  137. 137. • Double Tapered (DT) Light Post The new double taper posts that matches canal walls. ­ 4 times stronger than steel ­ Tooth conservative ­ Reduces tooth stress ­ Tapers with canal walls ­ Resists dislodgment, is retentive and has micro­mechanical attachement ­ Radiopaque ­Light transmitting / fibreoptic ­Flexes with dentine ­Easily removed with Reaccess Kit ­Translucent = invisible under restorations ­Aesthetic ­Does not compromise colour of an all ceramicc restoration www.indiandentalacademy.com
  138. 138. • The Original Light Post The Light Post is the latest evolution of the Composipost. The Light Post's translucency means it can be used with light cured or dual cured cements and adhesives. (Recommended is Bisco's post cement HiX for easy radiographic identification.) Parallel sided with step down ­ where the canal has already been prepared. www.indiandentalacademy.com
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  152. 152. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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