Aesthetic Efficiency in a Post-and-Core System
A 22-year-old female presented with a recently completed root canal on tooth No. 12. Upon discussion with the patient, it was agreed to restore the tooth with a post-and-core and an all-ceramic crown.
Universal Principles to Consider When Placing Posts
1.Preserve as much healthy tooth structure as possible
2.Avoid contamination of the root canal system
3.Restore the tooth as soon as possible after completion of the root canal
4.Use posts only when necessary to retain a core buildup
5.The post preparation should leave a minimum of 4 mm of gutta-percha at the apical end
The minimum length of the post below the crest of bone should be equal to the height of the tooth above the crest of bone.
6.Removal of the Temporary and Pre-Preparation Steps
First, the temporary material was removed to visualize the remaining tooth structure. A caries detection dye (Seek [Ultradent Products]) was used to ensure that all decay had been removed. The apical extent of the decay required the use of a laser to perform a gingivectomy to allow for the exposure of healthy tooth structure. Probing determined that we were not in violation of biological width; therefore, no osseous removal was required. Figure shows tooth No. 12 with the removal of all temporary material and carious tooth structure, as well as the exposure of the distoapical aspect of the tooth.
Next, a heated instrument was used to remove the gutta-percha. Radiographs were used to determine and ensure that there was a minimum of 4 mm of gutta-percha left in place to protect the apical seal.
Next, the smallest diameter of post drills was used to finalize the post space. In an effort to minimize the removal of healthy tooth structure, it is important to start with the smallest drill size available. With the post spaces created in both buccal and lingual canals, the tooth was then isolated with a disposable matrix (OmniMatrix [Ultradent Products]). Note that the post spaces are barely wider than the gutta-percha seen in the previous photo.
For this tooth, a tapered, prefabricated, resin reinforced fiber post system (LuxaPost [DMG America]) was selected. This system is tooth-colored, will bond to the resin cement that will be used (which will bond to the tooth), comes in a small diameter size, and has a modulus of elasticity that virtually matches that of dentin.
The doctor must provide a date of completion for any root canal therapy on a particular tooth if a core buildup on that tooth is to be supported by either a cast or prefabricated post. (Third-party payers may request a dated radiograph of the completed root canal treatment.)
A post is simply a dowel that is placed in the instrumented canal to retain the core buildup.
Because of the duplication of both purpose and function, the post in addition to the individual buildup is generally reimbursed only once per tooth. The standard exception would be if documentation indicated that the tooth was broken down to the extent that a buildup was necessary to perform the completed endodontic procedure. In such cases, both a core buildup (D2950) before the root canal and a post-and-core buildup after the root canal should be benefited.
Building up the anatomical core attached to a post is not a core buildup as identified by code D2950. When the third-party payer reimburses for a post-and-core on an endodontically treated tooth, the benefit administrator considers the core a completed entity that was payable with the attached post. It would appear inappropriate for the dental office to charge the patient (and/or third-party payer) to recontour or otherwise supplement the size and shape of the core with further build-up material.
When a practitioner simply prepares an endodontically treated canal and delivers a prefabricated post, the appropriate code to identify the procedure code would be D3950-canal preparation and fitting of preformed dowel or post. It is imperative that the same provider does not submit D3950 with either D2952 or D2954 for the same tooth.
Post Placement Technique
A total-etch technique was used to bond the post-and-core. First the entire preparation was acid etched for 20 seconds, then thoroughly rinsed, and lightly air-dried. Next, a fourth generation bonding agent was used (OptiBond FL [Kerr]), including the use of a dual-cured activator for the resin. For the cement, an automix, dual-cured composite resin build-up material (LuxaCore Z [DMG America]) was used. Use of a single material will allow for the entire procedure to be more efficient. The material, when initially extruded from the “gun,” is highly flowable and has a sufficiently low film thickness to be used as a resin cement. As it is a dual cure product, it will completely set in the canals. As a core material, it has excellent compressive strength and cuts with a hardness that duplicates that of dentin.
For post placement, a small amount of LuxaCoreZ was injected directly into the canals. Extrusion was stopped when the material just filled the canals. Then the LuxaPosts were put into place with a reciprocating motion. The reciprocating motion allows the cement to cover the entire canal’s space. Then the posts were held to place and light-cured for 10 seconds. This tack curing ensured that the posts were fully seated and also allowed for the rest of the LuxaCoreZ to be extruded to fill the matrix, creating the core of the restoration. The entire core was then light-cured (Demi [Kerr]) for 30 seconds with the matrix on. Next, the matrix was removed and the core was cured for another 30 seconds. Figure 6 shows final post-and-core before being prepared for the crown. From the beginning of etching to matrix removal, should take less than 4 minutes.
The crown preparation was then completed and readied for the final impression, bite registration, and temporization.
In contemporary dentistry, there is still a place for post-and-core restorations. Modern materials and techniques provide the opportunity to take advantage of our material technology to create a post-and-core complex that is strong, minimizes stresses to the endodontically treated tooth, is tooth-colored, and utilizes adhesive principles to create a post that is well-retained to both the tooth and the core material. The technique demonstrated in the case report presented herein exemplifies all the above advantages. In addition, the entire process can be completed in an extremely time efficient manner.