IN THE NAME OF GOD

POST AND CORE

Present by: Shabnam Abizadeh Niyari

DefinitionPost: is a metallic structure that is placed within the body of the root of a tooth that has had previouse root canal therapy.

Core: is the part of the post that shown in the tooth. It is the part of that can anchor a cop or crown.

Indications• ET teeth dry out over time and suggested more brittle and

may fracture more easily than non-ET teeth.• They are like a dead tree branch in comparison to one that

is alive ,so they tend to break a few years down.• They are likely to shear off because of biting forces. For this

reason, simple fillings do not usually restore them for very long. These teeth need to have crown placed in order to protect the investment in the root canal treatment.

Indications.Post does not strength the tooth structure..Its main function of post is the retention of a core to support the coronal restoration..The evaluation of whether a post is needed is based on how much natural tooth substance remains.

IndicationsConvenient features :1.Maximum retention with minimal loss of tooth structure.2.Simultaneous transfer of stress by core.3.Easy removal if failure treatment.4.Compatibility with crown.5.It must be with good apical seal and proper canal obturation.• Indications for: Molar Premolar Anterior

Molar• Many do not require a post because they have

more tooth substance and a larger pulp chamber to retain a core buildup.

• But it is required when extensive loss of natural tooth substance.

• It should be placed in the largest and straightest canal to avoid weakening the root too much during post space preparation and root perforation in curved canals.(distal canal for mandible and palatal canal for maxilla)

Premolar• Have less tooth substance and smaller pulp

chambers to retain a core buildup than molars.• Posts are required more often in premolars.• There are many anatomical characteristics must

be considered carefully during post space preparation to avoid perforating the root.

Anterior• Post may be necessary to retain the core so that

these can resist functional forces.• Few studies have concluded that a post is not

necessary in an ET anterior tooth with minimal loss of tooth structure.

• Special care must be exercised when placing posts in mandibular incisors, as they have thin roots in the mesiodistal dimension.

Post Types• Custom fabricated (cast)• Prefabricated• Fiber posts

Custom fabricated (cast)

Custom fabricated (cast)

Custom fabricated (cast)

Advantage:1.Accurately filled the canal regardless the shape.2.The core is permanently attached to the post unlike amalgam or composite that breaks away during impression.3.Good and mechanical properties.4.We can use indirect technique.Disadvantage:1.esthatic;as the metal shows through the newer all-ceramic restorations.one way to overcome this is to make a PFM post and core from a metal ceramic alloy.2.Requires two visits and laboratory fabrication.

Custom fabricated (cast)

Prefabricated

Prefabricated

Prefabricated

Prefabricated

Prefabricated

Advantage:1.Can be adjusted and inserted in a single visit.2.Can be used in multi-rooted teeth by using more than one.3.Tooth conservation.4.Good adaptation.5.Few laboratory procedure.Disadvantage:1.Low physical and mechanically prosperities (such as: amalgam corrosion and GICs low strength).2.Difficult procedures.3.susceptibility to micro-leakage.

Prefabricated

Fiber posts

Fiber posts

Fiber posts

Fiber posts

Fiber posts

Fiber posts

• Advantage:1.Lower elastic modulus and good distribution of stress.2.aesthetics.3.Low installation time.• Disadvantage:1.Poor adaptation to channel.

Ceramic posts (zirconia)

References:• www.Google.com• www.Bing.com• www.Slideshare.net• www.Sid.ir• Fixed prosthodontics, Shillingburg

Thank you for your attention

THE END