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Restoration of ndodonticallyTreated Teeth
Donna N. Deines, DDS, MSFixed Prosthodontics
Sources: Shillingburg et. al.Rosenstielet. al.
Post-Core (Dowel or Dowel-Core)
A post which fits within the canal and retains thecore, which replaces the missing coronal toothstructure.
Does not reinforce endodontically treated teeth. RCT should be gutta percha
Cast Post-Core / Custom Dowel
Custom cast post-core (dowel) Pre-fabricated Post-Core Treatment Planning: Assure Restorability
Remove all caries (before RCT) Assess adequate tooth structure. Determine periodontal health / lack of mobility Determine need for crown lengthening or
extrusion.
Treatment Planning: Restorability
Caries extent to bone level - consider C:R aftercrown lengthening
Evaluate bite-wing radiograph as well as PA Option for FPD or implant replacement
Role of tooth in restorative treatment
Usefulness for effective occlusion Abutment for prosthesis Esthetics Could the tooth be more effectively be replaced?
FPD or implant
Treatment Planning:Determine success of endodontic treatment
Asymptomatic Well-filled
Good apical seal No evidence of pathology
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Poor RCT Fill or Apical Seal:Re-treatment
Treatment Planning
Long-standing temporary filling Recurrent caries Non-restorability Contamination of RCT Re-treatment
Evidence of Pathology
Fractured root Periapical lesion Draining fistula Pain, mobility Isolated deep pocket
Root Resorption Considerations for Anterior Teeth
Intact moderate-size anterior: Bleach and composite resin Porcelain laminate veneer (fx tooth, discoloration) No post will weaken tooth
Anterior Teeth
Extensive coronal destruction Post-core necessary to provide crown retention Resists horizontal dislodging forces
Posterior Teeth
Greater loading vertical fracture Cuspal coverage always recommended .
Full crown with high fracture risk
Large circumference : post not necessary for lateralresistance just retention of core.
Pulp chamber retention / pre-fabricated post / pin-retention dependent on tooth structure.
Amalgam or composite resin
Molars
If a post is needed:
Palatal root of maxillary molars Distal root of mandibular molars (Buccal roots of maxillary and mesial roots of
mandibular molars small, concavities, curvature)
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Premolars
Use post/core only if roots are long, bulky, straight Use post if abutment / lateral stress / height:CEJ
diameter is great. Minimum 2mm axial wall covered by crown (ferrule
effect).
General ConsiderationsCast or Prefab PC / Pin/pulp chamber retention Thickness of tooth
structure surroundingcanal
Bulk / height of remainingcoronal tooth structure
Diameter / morphology ofroot
Bone support Role in final restorative
plan
General considerations :
RCT tooth as abutment for 1-pontic FPD RCT generally not indicated for free-end
RPD abutment. (esp. premolars)
Preparation of clinical crown
Conserve tooth structure Smooth sharp angles in cast post preps to minimize
cementation stress & casting accuracy.
Ferrule Effect Ferrule Effect
Encirclement of vertical axial wall to protectagainst fracture by counteracting spreadingforces generated by the post. Crown margin must be placed on solid tooth structure
or risk root fracture.
Ferrule Effect Anti-rotation
Pins, keyways, or remaining tooth structure. Peripheral distribution of retention and resistance
features of core enhance resistance of restoration.
Anti-rotation features
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Anti-rotation features
2 posts;Oval shape of pulpchamber;remaining toothstructure .
Canal Preparation
Rubber dam isolation: asepsis; protection Remove gutta percha and prepare canal in separate
procedures. Ideal time to make post space is immediately after
obturation.
Post-Core Considerations
Make post-core separately from final preparation. Marginal adaptation and fit Facilitates replacement of crown Facilitates FPD abutment preparation
Retention form of posts: geometry
Serrated Smooth - Threaded
Embedment: Post LengthRetention: 2/3 length of root (embedded in bone) andat least the length of clinical crown
Post Length
Post Embedment
Fracture resistanceFracture resistance ::Post length should extend to at least the distanceof which the root is supported in bone.
Threaded post / inadequate lengthof post fractured root
Post Embedment
Leave 4-5 mm apical seal Without endangering root thickness
1/3 diameter of root at its narrowest 1 mm surround of sound dentin at mid-root and beyond
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A cylindrical post with near perforationof mesial aspect of distal canal
Forces are directed outward along length of post Root fractures often caused by;
Too short a post Too large diameter
Safe removal of gutta percha
Peeso reamer Round bur
TwistdrillHeat Carrier - yes
Cutting instruments NO!
Perforations can be caused by anycutting instrument
Perforation of palatal root maxillary molar
Improper angulation from access preparation. Facial curvature hidden on radiograph.
Remove little if any additional dentinbeyond what is needed to perform the RCT
General guidelines for post design:
Conserve: remove little if any additional dentinbeyond what is needed to perform the RCT
Retain a minimum of 4-5 mm gutta-percha apically.
An adequate ferrule of minimum 2 mm verticalheight and 1 mm dentin thickness. Use a post designed to incorporate mechanical
features that resist rotational forces. Post length: place the post to extend apical to the
crest of the bone at least = height of clinical crown.
Modification of a cylindrical post
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Modification of post space by adding corematerial or casting to cylindrical post
Cast Post-Core Advantages:
Preservation of tooth structure(post fits space)
Anti-rotation properties Core retention (inherent part of
post)
Disadvantages: # of appointments necessary Decreased retention of tapering
design Wedging effect on root ????(If no flat root face vertical stop)
Cylindrical Pre-fabricated Post-Core
Advantages:
Increased retention w/in root Ease of placement
Disadvantages: Enlargement of canal for
post at apex for fit Core retention to post can
be problem Potential for rotation
Cast post-core using cylindrical serrated post Technique: Pre-fabricated Post-Core
1. Measure canal length2. Remove gutta percha (heat carrier)3. Enlarge canal (Peeso reamer)4. Drill post hole (twist-drill)
Pre-fabricated Post-Core
Fit the post; correct length; x-ray Note post #11 is not fully seated due to coronal contact
Place anti-rotation features, if necessary(grooves, pins)
Vlock Post Retentive Head
Active threaded design or Passive serrated design(threaded design root fracture)
Post Cementation
Etch; wash; dry (air and paper points) Coat post with cement Spin cement into canal with Lentulo spiral (ZnPO4) Seat using slow, finger pressure only
Pre-fabricated Post Composite Core
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Pre-Fabricated Post Composite Core
Resin must presentcontrast in posterior teeth.
Retentive headrequires resin core.
Pre-fabricated Post Amalgam Core
Place matrix band and condense amalgam;Leave slightly out of occlusion.
Cast Post-Core: Preparation
Internal walls must diverge (noundercut).No sharp internal angles.
Cast Post-Core: Pattern
Plastic post pattern fitted to lubricated canal withDuralay resin.
Coronal portion added w/ second mix of resin. Resin core shaped to crown preparation.
Cast Post-Core: pattern cast in gold
Resin pattern is invested and cast (type III gold). Vent is cut with inverted cone bur. Cementation complete crown preparation.
Provisional restoration for cast post-core
Internal wireor temporarypost Provisional crown
matrix combinesacrylic resin withpost.
Post Materials Cast metal (Type III gold; Au-Pd) Stainless steel Titanium
Ceramic / zirconium Fiber (carbon / quartz) / composite
Cast metal core to pre-fab post Pressed ceramic to ceramic post
Metal Dowel darkened root
Root discoloration oftencaused by internal debris,corrosion or microleakage.
Translucent posts: Ceramic / Composite Resin
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Ceramic post composite coreResin cementation of post
Ceramic Post - Composite CoreTranslucent post-core with all-ceramic crown
Reinforced Composite Resin Post
Modulus of elasticity same as dentin Post will not cause root fracture Fatigue causes fiber / composite breakdown and post
fracture Use only when well-supported by sound tooth
structure and lack of heavy lateral forces.
Inadequate post depth & retentionDissimilar metals - corrosion
Brass post amalgam core -corrosion
Short post in facial canal. Amalgam condensed into lingual canal(fractured).
Cast post-core:Retention / resistance from both canals.
(long post facial / short lingual)Contiguous metal structure resistsfracture.
Orthodontic and periodontal adjuncts torestoring damaged teeth
Regaining interproximal space Extrusion
Crown lengthening with osseouscorrection Root resection
Long-standing carious lesion on proximalsurface: migration of adjacent tooth
Orthodontic movement to create space
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Orthodontic movement
Core restoration placedand prepared for fullcrown.
Acrylic provisional crownis cemented.
Elastic orthodonticseparator is placed.
Orthodontic movement
0.6 mm ligature wirewrapped aroundcontact and tightened.
Check / tighten at 1-week intervals
Adjust occlusion Add contact to
provisional crown
Orthodontic movement
Adjust occlusion as
tooth is tipped. Surgical crown
lengthening mayalso be necessary.
Full crown is placed .
Extensive loss of tooth structure
Tooth structure lost to level of alveolar crestdoes not allow ferrule effect of crown toprotect from root fracture.
Surgical crown lengthening
Crown lengthening: osseous re-contour andapical re-positioning of flap (3 mm apical tocrown margin).
Deep cervical margin and bone resorption resultin un-esthetic difference in gingival height.
Can be due to deep fracture, caries, and crownlengthening surgery.
Orthodontic Extrusion
Normal anatomic C:R for CI is 11:14 Crown lengthening for 3 mm apical fracture
leaves unstable and unesthetic 14:11. Extrusion / crown lengthening 11:11 - more
esthetic and stable .
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Orthodontic Extrusion
Endodontics and post-core Arch wire with mid-facial loop and embedded
pin in provisional crown Elastic from pin to loop Movement of 1.0 1.5 mm / week
How much movement is necessary?
Distance the destruction extends apical to thealveolar crest
The biologic width of 2.0 mm 1.0 mm for sulcus apical to crown margin
Amount of extrusion desired 3mmBracket placed 3mm apical to center of post-core/provisional;
Arch wire placed in brackets .
Incisal lengthadjusted as toothmoves coronally.
#10 extruded foradequate ferrule withpost-core.Bone travels with root unesthetic gingival line(low).
Eruption of tooth and crestal bone
The descended level of gingiva and bone makesclinical crown shorter.
(The alveolar crest descends with the tooth.) Osseous re-contouring to level of adjacent tooth
allows equal length of clinical crown.
Facial tissuerecontouring withperiodontal surgery
Extract or Restore #13?Unfortunate clinical scenario -Patient desires FPD replacement of #13.
Over-reduction and over-convergence of MF wall#12 pulp exposure necessitates RCT. Near exposure on mesial #14 later needed RCT.
Improper angulation of access preparation nearperforation of mesial concavity.
Mesial perforation of root #12
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Preparations for Periodontally Weakened Teeth
Shoulder finish line extended onto rootsurface requires excessive axial reduction:possible pulpal involvement and weakeningof entire tooth
Conservative treatment:Prepare for metal-ceramic toCEJ;Long bevel or light chamfer metal collar
Furcation Flutes
Preparation finish line intersects with the vertical flutes inthe root trunk.
Axial surface of tooth preparation occlusal to the inversionof the gingival finish line must have a vertical concavity orflute, as will the crown. Like seating groove must parallel path of insertion .
The anatomic facial groove should merge with thevertical concavity extending from the furcation flute
The facial convexity should not be replicated in the restoration.
Root Resection Eradicate areas of tooth which cause
problems in hygiene maintenance. Salvage teeth with endodontic
problems. Must not have excessive bone loss. Furcationmust be in coronal 1/3 and
well separated roots. Must be treatable w/ endo.
DF and MF Root Resection on Maxillary Molars Mesial / Distal Root Resection onMandibular Molars
Mesial root resection #30
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Cast post-core distal root and FPD #29-30 Metal framework and metal ceramicFPD #29-#30
Facial and palatal root resectionson maxillary molars