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Decision Making in the Restoration
of Endodontically Treated Teeth

The post endodontic restoration plays an important role in tooth survival, in fact, endodontic success rate can drop from 90% to 18% because of a poor coronal restoration. 

The restoration of endodontically treated teeth has to be selected by following a process that considers the residual tooth structure, together with the clinical situation of the patient. 

The choice of the post endodontic restoration can go from the direct to the indirect restoration, with or without post. In the indirect restorations, one can choose between composite restoration or full crown. 

Risk factors

The risk factors that have to be taken into account when choosing between direct and indirect are the following. 

First of all, one has to consider the residual tooth structure: prerequisite for direct restoration is that the tooth has no undermined and thus weakened residual coronal walls.

In molars, one has also to consider function (group function Vs canine-protected occlusion), periodontal status, tooth location, number of adjacent teeth. 

Moreover, to decide if it is necessary to place a crown, other parameters as parafunctional habits, gender, age, dietary habits have to be taken into account. 

Prerequisite for direct restoration is that the tooth has
no undermined and thus weakened residual coronal walls

Crowns

Analysing the residual tooth structure, one can affirm that cuspal coverage for endodontically treated teeth lacking three or more coronal surfaces is advised, both crowns or composite onlays. Even if cusp replacement is generally carried out in indirect procedures, direct resin-based cusp replacement has shown equally effective. 

The Literature has shown that in two surface class II configuration the increase in fracture resistance through cusp replacement, though statistically significant, seems to be much less pronounced. Both composite restorations and porcelain fused-to-metal crowns are acceptable approaches for achieving good survival and success rates. In fact, the long term durability of class II posterior composites with 2.5 to 3 mm cusp thickness in ETT was clinically comparable to that of vital teeth.

The Literature can provide some important data regarding crowns: they are proven to function well as a long term restorative measure for endodontically treated teeth, and the preparation of a ferrule is deemed a decisive success factor in that context. On one hand crowns work very well, on the other hand, with classic crowning a significant amount of residual tooth structure is sacrificed. 

Criteria for deciding between direct and indirect restoration

When the tooth has:

• 3 or 4 coronal walls left

• at least one marginal ridge

• no undermined cavity

direct adhesive restoration may be considered as an alternative to cuspal coverage

For posterior teeth with few or undermined coronal walls, cuspal coverage with an adhesively placed onlay, a partial crown or a conventional crown is advised.

To post or not to post

The decision to place or not a post can be taken basing on the evidence reported in the Literature.
This is based as always on the function, the residual tooth structure and the position of the tooth.
To summarize, we can say as follows.

Incisors and canines

  • the only scenario where a posts gives a benefit to the tooth is that of decoronated teeth, with zero residual walls
  • possibility of fracture is greater in case of deep overbites, a horizontal envelope of function, extreme parafunctional forces may increase the possibility of fracture or loss 
  • in maxillary central incisors, tooth stability decreases starting with the preparation of the endodontic access cavity. 
  • preservation of tooth structure is a decisive factor for successful restoration of ETT: post space preparation should be kept at minimum. 

Premolars

  • the amount of residual coronal walls influences survival: the more residual coronal structure, the fewer failures
  • glass fibers posts reduce failure risks and protect against root fracture
  • in decoronated teeth, quartz fiber posts simnifically extend the time to restoration failure
  • no post when 50% or more of the coronal structure is preserved, especiallly when cusp protection is planned
  • the posts are ineffective in increasing the fracture resistance of teeth with cusp coverage

Molars

  • no post when 50% or more of the coronal structure is preserved, especiallly when cusp protection is planned
  • the posts are ineffective in increasing the fracture resistance of teeth with cusp coverage

References:

  • Mannocci F, Cowie J. Restoration of endodontically treated teeth. Br Dent J. 2014 Mar;216(6):341-6. doi: 10.1038/sj.bdj.2014.198. PMID: 24651340.
  • Atlas A, Grandini S, Martignoni M. Evidence-based treatment planning for the restoration of endodontically treated single teeth: importance of coronal seal, post vs no post, and indirect vs direct restoration. Quintessence Int. 2019;50(10):772-781. doi: 10.3290/j.qi.a43235. PMID: 31559397.
  • Bhuva B, Giovarruscio M, Rahim N, Bitter K, Mannocci F. The restoration of root filled teeth: a review of the clinical literature. Int Endod J. 2021 Apr;54(4):509-535. doi: 10.1111/iej.13438. Epub 2021 Jan 5. PMID: 33128279.
  • Shu X, Mai QQ, Blatz M, Price R, Wang XD, Zhao K. Direct and Indirect Restorations for Endodontically Treated Teeth: A Systematic Review and Meta-analysis, IAAD 2017 Consensus Conference Paper. J Adhes Dent. 2018;20(3):183-194. doi: 10.3290/j.jad.a40762. PMID: 29984369.

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Where are we placing the post?

Close to the wall that mostly needs support

PREMOLARS

Upper:
palatal root
buccal root if the buccal wall is missing

MOLARS

Lower: distal root
Upper: palatal root

How long should the post be?

1. Half of the length of the root surrounded by bone

How long should it be the post

2. Always consider the anatomy
3. Stop coronally to curvatures and splits

How long should the post be - 2nd part
A Randomized Controlled Trial of Endodontically Treated and Restored Premolars
M. Ferrari, A. Vichi, G.M. Fadda, M.C. Cagidiaco, F.R. Tay, L. Breschi, A. Polimeni and C. Goracci
J DENT RES 2012 91: S72 - DOI:10.1177/0022034512447949

Anteriors

Decision making process

Endo restho flowchartCoronal restoration incisors workflow
in these images you can find the decisional workflow to follow to decide when placing a fiber post.

And now some examples

1.

Access cavity 

No glass fiber post

Composite filling

There might be an exception for extremely wide canals, where the placement of a fiber post is advised in order too reduce the C-factor

2.

One ridge lost

No glass fiber post

Composite filling

3.

Two ridges lost

Glass fiber post

Ferrule and crown

4.

One wall remaining

Glass fiber post

Ferrule and crown

5.

No walls remaining

Glass fiber post

Ferrule and crown

Premolars

Decision making process

Premolars decision making process 3

And now some examples

1.

Access cavity 

No glass fiber post

Composite filling

2.

Three walls remaining

Check the thickness of the walls

Thickness > 2,5 mm

No glass fiber post

Composite filling/Inlay

3.

Three walls remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage 

4.

Two walls remaining

Check the thickness of the walls

Thickness > 2,5 mm

No glass fiber post

Cusp coverage

5.

Two walls remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage

6.

One wall remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage

7.

One wall remaining

Check the thickness of the walls

Thickness > 2,5 mm

No glass fiber post

Cusp coverage

8.

One wall remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage

9.

No walls remaining

Glass fiber post

Ferrule and crown

Molars

Decision making process

Molars decision making process

And now some examples

1.

Access cavity 

No glass fiber post

Composite filling

2.

Three walls remaining

Check the thickness of the walls

Thickness > 2,5 mm

No glass fiber post

Composite filling/Inlay

3.

Three walls remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage 

4.

Two walls remaining

Check the thickness of the walls

Thickness > 2,5 mm

No glass fiber post

Cusp coverage

5.

Two walls remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage

6.

One wall remaining

Check the thickness of the walls

Thickness > 2,5 mm

No glass fiber post

Cusp coverage

7.

One wall remaining

Check the thickness of the walls

Thickness < 2,5 mm

Glass fiber post

Cusp coverage

8.

No walls remaining

Glass fiber post

Ferrule and crown

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