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PresRes 3 > Posts and Core > Flashcards

Posts and Core Flashcards

1
Q

Moisture Content of ETT

A
  1. moisture levels between ETT and vital teeth are not different
  2. dehydration alone doesn’t account for changes in physical properties
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2
Q

Flexibility of ETT

A
  1. less flexible compared to vital teeth

2. endo tx alone affects stiffness only by 5%

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3
Q

Proprioception of ETT

A
  1. ETT requires 57% higher pressure to initiate a pressoreceptive response
  2. ETT have pain threshold levels that are more than 2X as high as those of vital teeth
  3. RESULT: failures due to patients not being aware of applied force
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4
Q

Classic Physical Properties of ETT

A
  1. hardness, load to fracture, toughness, strength (compressive, shear, tensile)
  2. no definitive conclusions due to considerable variation amount the various studies
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5
Q

Structural Integrity of ETT

A

higher occurrence of fracture

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6
Q

To crown or not to crown an ETT?

A
  1. due to extensive loss of tooth structure, full coverage restoration usually indicated
  2. EXCEPTION: anterior ETT with very conservative access
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7
Q

Endodontic Posts

A
  1. pin usually made of metal that is fitted into prepared root canal of a natural tooth
  2. provides retention and resistance for the restoration when combined with an artificial crown or core
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8
Q

Purpose of Endodontic Posts

A
  1. decreases fracture resistance of ETT (EXCEPTION…ETT with thin root canal walls due to over-instrumentation)
  2. MAIN PURPOSE: provide retention of the core
  3. RESULT: if the core can be retained without a post, a post isn’t necessary (more than 50% of tooth structure remains)
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9
Q

Desirable features of endodontic posts

A
  1. should not cause root fracture
  2. retentive in the root
  3. retain core material
  4. provide adequate coronal seal
  5. esthetic
  6. radiopaque
  7. biocompatible
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10
Q

Fabrication methods of posts

A
  1. pre-fab

2. custom

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11
Q

Design of posts

A
  1. tapered: less retentive
  2. parallel sided: more retentive
  3. threaded
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12
Q

Fit of posts

A
  1. passive

2. active: more retentive, but cause fractures

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13
Q

Material of posts

A
  1. metallic (stainless steel, titanium, gold)

2. non-metallic (glass fiber reinforced, quartz fiber reinforced, carbon fiber reinforced)

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14
Q

Advantages of pre-fab posts

A
  1. post and core completion in one appointment
  2. tooth can be immediately provisionalized
  3. can be more esthetic
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15
Q

Disadvantages of pre-fab posts

A
  1. separate core material necessary

2. available sized may not match canal shape

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16
Q

Pre-fab post technique

A
  1. ETT with temporary material
  2. temporary material removed
  3. size-associated drill is used to re-shaped canal to proper length and width
  4. post is tried in, shortened, and cemented
  5. core build-up made with composite resin, prepared to resemble complete tooth prep
17
Q

Features of custom cast post/cores

A
  1. post and core are one piece
  2. customized to canal shape
  3. needs two appointments
  4. Indications: loss of significant tooth structure, canal has circular shape
  5. expensive!!
18
Q

Custom cast post/cores technique

A
  1. pre-fab plastic pattern
  2. pattern resin-powder and liquid
  3. monomer applied to plastic pattern
  4. resin applied to plastic pattern
  5. coronal resin is added to form core
  6. resin prepared to resemble a complete crown prep
  7. post/core resin pattern removed and sent to lab
19
Q

Post length

A
  1. general guidelines: 2/3 to 3/4 of root canal length
  2. must have at least 4 mm of apical seal, ideally 5 mm
  3. long roots: as long as possible while retaining 5 mm of apical seal
  4. molars: post should not extend more than 7 mm apical to root canal orifice
  5. anterior and premolars: extend half way the root portion that is embedded into bone
20
Q

Post diameter

A
  1. general guidelines: shouldn’t exceed 1/3 of root diameter
  2. post size should be between 0.6 mm-1.2mm depending on tooth size
  3. primary roots, D roots of mandibular molars, P roots of maxillary molars (need to have more than 1 mm of dentin around post)
  4. IMPORTANT: protects tooth from perforation, increases fracture resistance
21
Q

What should be considered with the post diameter?

A
  1. root size and curvature
  2. place post into D root of mandibular molars
  3. place palatal root of maxillary molars
22
Q

Biological Width

A
  1. distance between crestal bone and deepest point of sulcus
  2. 2 mm in most patient
  3. SHOULD not be violated
23
Q

Ferrule Effect

A
  1. band of metal that surrounds tooth, which greatly increased fracture resistance
  2. ideally need 2 mm of circumferential tooth structure
  3. MORE IMPORTANT THAN POST LENGTH
  4. remaining coronal tooth structure is the most important factor for good long term prognosis
24
Q

What if the ferrule is less than 2 mm?

A
  1. sub-gingival margin placement (DON’T violate biological width)
  2. crown lengthening
  3. orthodontic extrusion
  4. tooth extraction
25
Q

Complications of restoring ETT

A
  1. post loosening
  2. root fracture and root perforation
  3. caries and periodontal disease
26
Q

Desirable features of core materials

A
  1. high compressive strength
  2. dimensional stability
  3. easy to use
  4. short setting time
  5. ability to bond to both post and tooth
  6. esthetic when applicable
27
Q

Types of core materials

A
  1. composite resin core
  2. amalgam core
  3. cast core
28
Q

Composite resin core

A
  1. bond to teeth
  2. short setting time
  3. easy to use
  4. relatively strong
  5. tooth can be prepared for crown the same day
29
Q

Amalgam core advantages

A
  1. very strong
  2. easy to use
  3. material with longest history of success
30
Q

Amalgam core disadvantages

A
  1. crown prep cannot be complete the same day
  2. environmental concerns
  3. corrosion potential
  4. discoloration of dentin or gingiva
31
Q

Summary

A
  1. purpose of post is to retain artificial core
  2. post space prep should be conservative (AT LEAST 1 mm of radicular dentin around the post)
  3. always maintain adequate apical seal (IDEALLY 5 mm, minimum 4 mm)
  4. remaining coronal tooth structure is most important for success (2 mm ferrule and 2 mm biological width)
32
Q

Restoring ETT Summary

A
  1. Ferrule: at least 2 mm long
  2. BWD: at least 3 mm (sulcus=1 mm, BW=2 mm)

Total: at least 5 mm from bone to most coronal area

Proposed finish line: margins must be in sound tooth structure

PresRes 3 (6 decks)

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