To Thine Own Self Be True

The author presents a sequel for “To Post or Not to Post.”

By John C. Comisi, DDS, MAGD

In the author’s October 2011 Inside Dentistry article, “To Post or Not to Post,”¹ discussion revolved around the methodologies of using posts and cores, whether to use metal or fiber or no post at all, and the need for good ferrule incorporation into the preparation for resistance and retention of the artificial crown. The feedback the author received from various endodontic specialist colleagues was very interesting in that almost all of the comments regarded a specific issue that endodontists encounter: The creation of post room by the endodontist after endodontic therapy is completed. It seems that there are occasions when the general dentist requires the endodontist to create “post room” even if the treated tooth does not require it.

The question the author posed in response was, “Why?” Why would post room be requested, or even required, if there is more than adequate tooth structure for a good, quality restoration to be created with significant resistance and retention? The answer, of course, is that there is no good reason to do so.

Good clinical judgment is paramount in every treatment that dental professionals render. If we wish to maintain our integrity as a profession and the trust of the patients we serve, we must ethically and professionally determine the appropriate care and treatment based on clinical evidence. In the author’s opinion, there can be no compromise on this point for any reason. There may be excellent reasons for the restoring dentist to create or request post room to be created by the endodontist, and in all likelihood one could speculate that the endodontist would concur and do so when it is indicated. To, in essence, request that a specialist colleague create post room in sound tooth structure when there is no need to do so, or to initiate any other questionable procedure for that matter, is compromising the referral trust and partnership. Consequently, the author has been asked to seek out and investigate other new post-and-core materials for consideration when these procedures are indeed needed in the restorative process.

Post-and-Core Systems and Materials

Spirapost PFS™ by DMG America (www.dmg-america.com) is a unique product that incorporates polyfiber strands (hence the PFS in the product name). It consists of surgical stainless-steel wire twisted around biocompatible polyfiber strands, creating a “caterpillar” shape (Figure 1). This configuration appears to allow the post to travel down the canal and conform to the canal’s unique shape. The polyfiber strands act as a scaffold or rebar for the post cement and the restorative core material to flow through and build on, creating a strong structure that absorbs and distributes external forces to help minimize the risk of failure.

LuxaCore^® Z Dual, also by DMG America, builds upon the successes of Luxacore Dual and improves it by creating a product that, according to the company, shows an increase in strength of 31% over the original product (Figure 2). This is accomplished by the addition of zirconium dioxide via a patented nano-technology process that virtually eliminates particle agglomeration (clumping) within the resin matrix and helps to reduce the film thickness to 20 µm, which enhances the flow characteristics. Additionally, the inclusion of the zirconia provides exceptionally high compressive strength and makes the cutting and polishability of the material more like that of dentin. The manufacturer recommends that a dual-curing adhesive system be used with this material. Even so, this one product includes a cementation and core build-up material in one easy-to-use package, which, in the author’s opinion, is certainly a compelling reason to consider this for use in these procedures.

Grandio^® SO by VOCO America (www.vocoamerica.com) is the latest addition to this company’s line-up (Figure 3). As a flowable dual-cure material designed for core build-ups and the luting of root posts, it has a filler content of 77% by weight, and thus should be able to provide durable restorations. Like most dual-cure materials, it is supplied in a dual-chambered delivery unit with the material mixed through a mixing syringe tip. According to VOCO, the material is highly radiopaque and available in three shades (dentin, blue, and white), and can be used with all enamel/dentin adhesives.

FibreKleer^® 4X™ Fiber Post by Pentron Clinical (www.pentron.com) is a strong, esthetic, and highly radiopaque post system (Figure 4). According to the company, the high radiopacity is up to 400% of aluminum, which helps to ensure that the posts are easily identified on radiographic images. The posts are composed of translucent glass fibers bundled in a proprietary clear resin matrix that provides exceptional flexural strength and helps to preserve the natural lifelike esthetics needed with all-ceramic restorations. They are engineered with a flexural modulus that is similar to dentin. This enables the post to flex with the tooth and transmit stress more evenly along the remaining root structure to minimize the instance of root fractures as compared to metal posts. The posts are color-coded to correspond to the corresponding drill and are available in three body designs: Parallel with a retentive head, Tapered, and Original, enabling the clinician to choose the type of post that best suits each individual case.

Build-It^® FR™ Fiber Reinforced Core Material, also by Pentron Clinical (Figure 5), contains all of the features of an ideal core build-up material: It cuts like dentin, contains fluoride, is dual-cured, and is radiopaque. According to the company, the addition of specially treated glass fibers enhances the material’s compressive strength. It is available in dual-chambered automix cartridges, is syringeable and stackable, and comes in five shades: A2, A3, Opaque White, Gold, and Blue.

D.T. Light-Post^® Illusion™ X-RO^® by BISCO (www.bisco.com) features a double-taper design and fiber-optic construction to allow light to easily be transmitted through the post during cementation with light-cured or dual-cured materials (Figure 6). According to BISCO, these posts exhibit high flexural strength, are radiopaque for easy detection on radiographs, and have “color-on-command” technology. When the post is placed intraorally the intrinsic color of the post disappears, allowing it to blend into the natural dentition. If re-treatment or removal is ever required, the post will reappear on command simply by spraying cold water. They are available in four sizes, with each post being color-coded and concurrently matching the drill markings used to create the post room. Additionally, a free 6-year limited warranty is available within the United States.

Spee-Dee Build-Up by Pulpdent (www.pulpdent.com) is a multi-purpose core and tooth build-up material that is dual-cure, fluoride-releasing, radiopaque, and has a moisture-tolerant resin chemistry (Figure 7). Pulpdent calls it the “spee-dee” way to build up broken-down teeth. The material is self-adhesive and self-etching to dentin, and enables a one-step post-and-core build-up that can help ensure a homogenous, one-piece internal structure that cuts like dentin. Rotary instruments transition smoothly from the tooth to the build-up material, cut accurately, and do not ditch, gouge, chatter, or gum up. The material comes in an automix cartridge with angled tips for controlled dispensing.

Conclusion

As in the author’s previous article on post-and-core materials, the various materials discussed in this article are presented to expand the reader’s awareness of and knowledge about these materials, so that dentists can make informed choices about which tools they should add to their clinical armamentarium. It has been suggested in various publications^2,3 that, “It is best for an endodontist to prepare a post space within the anatomy of the canal. When the restorative dentist does not follow the path of the canal anatomy in preparation for the post placement, failure can follow…”

Is this the basis for the “requests” discussed at the beginning of this article? Is it true that the restorative dentist is not able to create post room properly? The author would submit that the answer is yes and no. The restoring dentist may have been “advised” that they may not be able to effectively or safely create these post-room preparations, so they may be passing it along to an endodontic specialist in order to reduce their liability. But it is the author’s contention that with proper training and by paying close attention to the various nuances of the anatomy and direction in which the posts are placed, the restoring dentist can perform this or any other procedure. Knowing the limits of your ability is the most crucial component of day-to-day practice. As the Bard wrote in Hamlet: “This above all: To thine own self be true, and it must follow, as the night the day, thou canst not then be false to any man.”