Post placement and restoration of endodontically treated teeth; literature…
Post placement and restoration of endodontically treated teeth; literature review
ARE ENDODONTICALLY TREATED
Thought that the dentin in endodontically treated teeth was more brittle because of water loss,and loss of collagen cross-linking
Neither dehydration nor endodontic treatment caused degradation of the physical or mechanical properties of dentin
The study did not support the conclusion that endodontically treated teeth are more brittle
RESTORATIVE FACTORS THAT AFFECT THE
PROGNOSIS OF ENDODONTIC TREATMENT
Contamination of the root-canal system by saliva, often referred to as “coronal leakage” caries or fractured restorations
Exposure of coronal gutta-percha to bacterial contamination can lead to migration of bacteria to the apex in a matter of days. Retreatmen should be consider.
Prevented during after endodontic treatment.
glass-ionomer cement or composite resin are preferred.
etched and primed if a resin material is used or “conditioned” if using glass-ionomer
. The barrier material is then placed over the floor of the chamber and light cured, and a temporary restoration is placed with or without a cotton pellet in the chamber.
When the tooth is restored with a “permanent” restoration,
bonded restorations should be used as much as possible to minimize microleakage.
Cuspal coverage was one of the significant factors that
predicted long-term success
INDICATIONS FOR A POST
Retain a core in a tooth with extensive loss of coronal tooth structure
Accidents include perforation in the apical portion
Root fracture and treatment
failure , especially if an oversized post channel is prepared. For these reasons, posts should only be used when other options are not available to retain a core.
A post is of little or no benefit in a structurally sound
anterior tooth and increases the chances for a nonrestorable
If an endodontically treated anterior tooth is to receive a crown, a post often is indicated
The pulp chambers are too small to
provide adequate retention and resistance without a post.
The amount of remaining coronal tooth structure and the functional requirements of the tooth determine whether an anterior tooth requires a post
Unless the destruction of coronal tooth structure is extensive, the pulp chamber and canals provide adequate retention for a core build up
Molars must resist primarily vertical forces.
The post should be placed in the largest, straightest canal,
which is the palatal canal in the maxillary molars and a distal canal in the mandibular molars.
Require posts more often than molars
The remaining tooth structure and functional demands
are, once again, the determining factors.
IMPORTANT PRINCIPLES FOR POSTS
Retention and Resistance
Post retention refers to the ability of a post to resist vertical
-The luting cement used, and whether a post is active or passive.
Active posts are more retentive than passive posts
Retention can be increased slightly by
enlarging the post diameter
Resistance refers to the ability of the post and tooth to withstand lateral and rotational forces.
Fiber posts, tend to have failures that are more likely
to be restorable
Teeth prepared with a ferrule also tend to
fail in a more favorable mode.
The Ferrule Effect
“ferrule effect”, t adds some
retention, but primarily provides resistance
A ferrule with 1 mm of vertical
height has been shown to double the resistance to fracture versus teeth restored without a ferrule
Preservation of Tooth Structure
Preparation of a post space should require minimal removal of additional radicular dentin beyond the requirements for root-canal treatment.
Bonded posts are reported
to strengthen the root initially, but this strengthening effect is probably lost over time as the tooth is exposed to functional stresses.
PROGNOSIS FOR ENDODONTICALLY TREATED
TEETH RESTORED WITH POSTS
Amount of remaining
coronal tooth structure and the quality of the coronal seal
TYPES OF POSTS
Active Versus Passive Posts
Most active posts are threaded and are intended to engage the
walls of the canal, whereas passive posts are retained strictly by the luting agent. Active posts are more retentive than passive posts, but introduce more stress into the root than passive posts
Parallel Versus Tapered Posts
Parallel metal posts are more retentive than tapered posts
Parallel posts induce less stress into the root, because there is less of a wedging effect, and are reported to be less likely to cause root fractures than tapered posts
Prefabricated Post and Cores
Prefabricated posts are typically made of stainless steel, nickel
chromium alloy, or titanium alloy. They are very rigid, and
with the exception of the titanium alloys, very strong.
Custom Cast Post and Cores
Cast post and cores were the standard for many years and are still used by some clinicians
Require two appointments, temporization, and a laboratory fee.
When multiple teeth require posts, it is sometimes
more efficient to make an impression and fabricate them in.
Ceramic and Zirconium Posts
White and/or translucent
Require removal of
additional radicular tooth structure.
Fexible than metal
posts and had approximately the same modulus of elasticity as dentin
PREPARING THE POST SPACE
Minimal enlargement of the canal
Gutta-percha can be removed with the aid of heat or chemicals, but most often the easiest and most efficient method is with rotary instruments.
length equal to 3⁄4 of root canal length, if possible, or at least equal to the length of the crown. They caution that 4 to 5 mm of gutta-percha should remain apically to maintain an adequate seal.
Zinc phosphate, resin, glass ionomer, and resinmodified
Bonded resin cements have been recommended for their strengthening effect in roots with thin walls
Dentin/resin/post can be joined via resin adhesion
into one unit, at least for a period of time
The post should be cemented with
an auto-cure or dual-cure resin cement
Glass-ionomer materials, including resin-modified glass
ionomer, lack adequate strength as a buildup material
and should not be used in teeth with extensive loss of tooth structure.
Amalgam ood physical and
can be clumsy when there is minimal coronal tooth structure
Amalgam can cause esthetic problems with ceramic crowns and sometimes makes the gingiva look dark. There also is a risk of tattooing the cervical gingiva with amalgam particles