Single-Unit Crown - Post Placement in Endodontically Treated Teeth

Contents:

• The role of a post 
• When to place a post vs. when not to place a post
• When should a core build-up be performed?
• Achieve Long-term Success for Endodontically Treated Teeth with Help from Dentsply Sirona 

Along with the endodontic treatment itself, we know that coronal restorations influence the long-term success of endodontically treated teeth. Based on one large study, the success rate for endodontically treated teeth was 96% over eight years, while 85% of the failures were due to poor coronal coverage.¹ This data highlights how critical good restorative care is for successful outcomes in endodontically treated teeth. Here, we’ll review the role of a post, and when a post and core build-up should/should not be placed.

The role of a post 

A post is defined by the American Association of Endodontists as ‘A custom or preformed rod that is fitted and cemented into the root canal of an endodontically treated tooth for core retention.²

The traditional role of a post is to retain a core build-up when insufficient coronal tooth structure remains to support the core. Glass fiber posts adhesively luted are now considered the gold standard.

When to place a post vs. when not to place a post

Two primary factors must be considered in determining whether a post should be placed are:

• The amount of tooth structure, marginal ridges and number of walls remaining.
• The position of the tooth in the dental arch.

In addition, the presence of risk factors predisposing endodontically treated teeth to fracture influences clinical decision-making. Here we’ll first look at clinical recommendations generally indicated, using a minimally invasive approach when possible, and then consider the risk factors.

If an indirect restoration is necessary, when is a post needed?

An indirect restoration is needed when both ridges are lost, one wall remains, or no walls remain. The assessment of coronal walls must be based on what will remain after tooth preparation. It’s essential to visualize what the remaining tooth structure will look like after preparation. How many coronal walls will remain, and will the walls be sufficiently thick? For example, caries removal during preparation may result in thin and/or fewer coronal walls.

The type of indirect restoration and need for a post is then evaluated based on the number of walls present and whether the tooth is an incisor, premolar or molar, as follows:

• Incisors– A post is needed as well as a ferrule and crown if both ridges are missing, only one wall remains, or no walls remain.
• Premolars – a post is always needed if both ridges are missing, only one wall or no walls remain regardless of whether a single-unit crown is indicated or cuspal coverage (an adhesively luted onlay, partial crown or standard crown). A ferrule and single-unit crown are always needed if no walls remain. 
• Molars – a post is always needed if no walls remain, along with a ferrule and single-unit crown. Cuspal coverage without placement of a post may be possible if both ridges are lost or at least one wall remains (in contrast to incisors and premolars, molars present with more residual hard tissue). (Table 1)

If a post is needed, which type of post is best?

Options for posts include custom/pre-fabricated metal or ceramic posts as well as carbon fiber posts and glass fiber posts. Research supports the use of a tapered glass fiber post as the gold standard, with a modulus of elasticity (stiffness), coefficient of thermal expansion and compressive strength similar to root dentin. Overall, glass fiber posts exhibit:

1. An overall survival rate of 92.8% compared to 78.1% for metal posts⁵
2. Non-catastrophic failure rate of 14.2%, compared to 22.6% for carbon fiber posts and 22.1% for cast metal posts⁵
3. Catastrophic failure rates similar to cast metal posts (3.6% vs 3.4%) and much lower than carbon fiber posts or prefabricated metal posts.⁵

When should a core build-up be performed?

The role of the core is to retain a crown. A core build-up is usually placed when more than half of the coronal tooth structure is missing and deemed to be insufficient for retention of the indirect restoration. When a fiber post is selected to retain the core build-up, its taper helps to preserve tooth structure in the root canal and the post can be adhesively bonded to both the tooth structure and the core build-up.   Selecting a fiber post helps with clinical success when a post is needed, with a 2.7-fold reduced risk of failure found for all-ceramic crowns in one study and significant reductions in failure rates for premolars in a second study.^7,8 

In summary, knowing when and when not to place a post and core build-up is essential for an optimized restorative treatment plan and clinical success. When a post is needed, selecting a fiber post is a gold standard that helps in achieving favorable long-term outcomes for endodontically treated teeth.

Achieve Long-term Success for Endodontically Treated Teeth with Help from Dentsply Sirona

Here at Dentsply Sirona we want to support you with products that help you achieve successful long-term outcomes for endodontically treated teeth. That’s where Dentsply Sirona’s FluoroPost™ Endodontic Fiber Post, Fluorocore® 2+ Core Build-Up and Prime&Bond active® Universal Adhesive come in, together meeting your post, core build-up and adhesive needs.

Best Post to Use

When you need to place a post, Dentsply Sirona’s FluoroPost™ Endodontic Fiber Post is a glass fiber post that delivers high bond strength⁹ without any extra pre-treatment such as sandblasting to treat the surface. Glass fiber posts keep catastrophic and restorable fracture rates low, increasing the overall longevity and success of your final crown restoration.⁵ The tapered shape of this post perfectly fits to the provided precision drill helping you achieve a precise fit, and with a modulus of elasticity similar to dentin a high level of fatigue resistance and reduced stress is achieved.¹⁰

Best Core Material to Use

Dentsply Sirona’s Fluorocore® 2+ Core Build-Up is both an ideal build-up material and post cement. With its high bond strength and strong dark cure it delivers reliable bonding^,11 and for core build-ups provides high compressivtensile, and flexural strengths^.12 Fluorocore® 2+ Core Build-Up properties also delivers following:

• Dual curing
  • Reliable dark cure deep into the root canal
  • Convenience of light cure for the upper part of the core build-up
• Cuts like dentin and easy to use
• Good radiopacity for radiographs
• Dual-purpose for convenience

Best Adhesive to Use

For long-lasting results excellent bonding of the indirect restoration is also required. Dentsply Sirona’s Prime&Bond active® adhesive offers a low film thickness, versatility, and can be used with all etching techniques. When combined with the Self-Cure Activator, the mixture can be used for priming the post as well as well as adhesive within the post space and for bonding the core build-up.

Here at Dentsply Sirona we want to support you further with our entire online dental academy complete with webinars, how-to videos, and real-world examples on how to create streamlined solutions with efficient procedures and even greater patient satisfaction. Contact us now and let’s get started!