Aesthetic Post and Core to Complement the All-Ceramic Crown

Tooth preservation and enhanced appearance are both key factors that challenge dental professionals when they are treatment planning cases. With the patient population base living longer and maintaining its dentition, procedures that preserve the teeth while advancing aesthetics are in high demand. Realizing this potential, the progressive dental team can take advantage of these treatment options to enhance the practice. The introduction of improved and predictable dental materials and technologies create the opportunity for alluring aesthetic restorative procedures. 

After many decades of functional load, large restorations, caries, and general breakdown, the natural dentition may require comprehensive care. Due to these various conditions, endodontics is often performed to preserve the remaining root and coronal structure. Subsequently, there is often a postendodontic need to re-establish the lost coronal foundation by use of a direct post and core system. This is usually followed by some type of crown placement as the final restorative measure. Similar situations that are present in the anterior portion of the dentition require greater scrutiny relative to aesthetic treatment options available. These everyday operations can be simplified by approaching them one project at a time.

Very often the patient has neither the desire nor the financial means for an all-inclusive major reconstruction at one time. Further, modern restorative dentistry mandates the implementation of systems that are not only strong but also very aesthetic in nature. These 2 restorative criteria are available to practitioners through the use of fiber-reinforced post and core systems and all-ceramic crowns. With these materials the clinician can confidently proceed in prescribing this treatment modality for his or her patients and realize the very positive impact this regimen can have on the practice.

CASE REPORT

Figure 1. Preoperative labial view of No. 7. Figure 2. Preoperative radiograph of No. 7.

A 70-year-old male patient was referred to my office for restorative evaluation. Clinical examination  revealed significant attrition of the maxillary anterior segment along with multiple large composite restorations. The maxillary lateral incisors had both been treated with endodontics, and tooth No. 7 had been temporarily shrouded with composite (Figure 1). There was very little residual coronal structure remaining as determined by the radiograph (Figure 2). Occlusal analysis indicated very limited overbite and overjet. The periodontal support was very favorable, with slight gingival inflammation.

After completing the oral exam and analysis, full-arch maxillary and mandibular alginate impressions were taken for study models. An interview was conducted with the patient regarding a personal assessment of his smile and what goals he deemed most important. He stated his main goals were to preserve the anterior teeth and to enhance their appearance in a subtle way. Arch symmetry and tooth length were acceptable along with the intrinsic coloration of his teeth. This was all noted, and the patient returned for a second appointment to discuss treatment options and recommendations.

Figure 3. Armamentarium for post and core.

Based on all these factors plus important dental insurance criteria, a treatment plan was established. This year our only focus would be reconstruction of tooth No. 7. This would require placement of a post/core complex followed by a full-coverage crown. Teeth Nos. 8 to 10 would undergo therapy over the next couple of years with similar placement of a post/ core on tooth No. 10 and crowns on all 3 teeth. Due to the very apparent location of tooth No. 7 visually, a decision was made to optimize the appearance through the use of aesthetic restorative materials. The post and core placement would be accomplished by employing the ParaPost Fiber Lux System (Coltène/Whaledent, Figure 3). The entire restorative armamentarium also includes an adhesive cement and fiber-reinforced core material to complement the system (Figure 3). The cement kit’s adhesive qualities would lead to increased retentive capabilities of the post, and the increased strength of the fiber-resin core would increase durability and provide favorable properties for preparation.

The Fiber Lux Post kit provides increased flexural strength, transillumination properties, and natural aesthetics. After the foundation completion, the case would be finished by placement of a Procera ceramic crown (Nobel Biocare). It has been the author’s experience that not only is this aluminous, core-based system very strong and beautiful in appearance, but it also is extremely accurate in fit and marginal adaptation. The post and core system would help emulate color from within in addition to enhancing and complementing the shade of the all-ceramic crown. This is due in part to the vitality and translucency this ceramic system affords.

The key factor was to blend this one very functional tooth with the other anterior teeth in a natural but enhanced way. This would be the true measure of success. A number of essential elements would be integrated for this case to achieve the desired outcome.

Figure 4. Digital photo with Kodak camera. Figure 5. X-rite spectrophotometer for shade taking.

Before beginning any therapy requiring shade-matching techniques, it is important to complete this step at the very beginning of the appointment. As treatment progresses during the appointment the teeth will dehydrate and create an erroneous reading. Three scientific devices help ensure a proper tooth match along with good visual acuity. The first and foremost device for shade communication with the dental laboratory is a photo taken with a high-quality digital camera. I have tried many digital cameras and have been most impressed with the Kodak DX7590 dental digital camera (Kodak, Figure 4). This camera coupled with the Easy Share 600 dye-sub printer dock (Kodak) provides an excellent color rendition of the teeth in a couple of minutes. Following this procedure a shade was selected using the X-Rite Shade Vision device (X-Rite). This equipment offers a quick, precise color reading of the appropriate teeth (Figure 5). It offers the clinician and dental technician a color map of the tooth, which is invaluable for the eventual porcelain buildup of the crown. The shade (3L-2.5) that the Shade Vision selected was verified visually by use of the Vita 3-D shade guide (Vident), which offers a wonderful array of tooth colors and in my estimation is deemed the foremost guide.

Figure 6. Comparing post to radiograph.

Following these 3 tasks, an assessment was made of the canal in tooth No. 7 for approximate length and width of the post to be placed. With the radiograph as a backdrop, the appropriate size post was placed on top to verify dimensions. In this case, the yellow (1-mm diameter) ParaPost Fiber Lux was selected as the best size to fit the canal (Figure 6). The goal was to place the post two-thirds down into the canal and also maintain a solid thickness of lateral radical dentin. This feat was accomplished by initiating gutta-percha removal with a Gates Glidden Drill to the appropriate depth.

Figure 7. Reaming of canal. Figure 8. Try-in Fiber Lux post.

The proper size ParaPost reaming drill (in this case, yellow) was then used to shape the canal to accept the post (Figure 7). This parallel-sided system allows for intimate fit of the post and excellent retention. After ensuring depth placement by comparing drill guide marks to the radiograph, the yellow Fiber Lux post was tried in (Figure 8). This step verifies fit, seating, and extent of the head portion extending out from the canal orifice. This post, due to its modulus of elasticity, allows dissipation of forces, and the rounded head design allows for great retention and stress distribution of the core.

Figure 9. Placement of adhesive into canal. Figure 10. Placement of cement into canal.

There are 3 steps in the adhesive cementation process of the post with the ParaCem Kit (Coltène/Whaledent). The resin content of the post allows for bonding with resin cement. Step one was to apply the black-bottle, nonrinse conditioner into the canal to the most apical portion. This was done by use of a Micro Tip (Microbrush); the material was allowed to remain stagnant for 30 seconds (Figure 9). Excess was removed with a paper point and lightly air-dried. Following this, one drop of adhesives A and B (red and yellow bottles) were mixed and used to similarly saturate the canal. Excess fluid was removed, and gentle drying formed a thin layer of adhesive within the canal. Now the post was ready to be cemented into place with the dentinal shaded ParaCem by dispensing equal amounts of base and catalyst (2 syringes) and mixing for 30 seconds. This dual-cure, fluoride-releasing material has a low film thickness and flows very well. It was injected into the canal using a Centrix gun and Access tip (Centrix). This small orifice needle was extended to the most apical portion of the canal while constantly withdrawing it so as not to trap air. Once the canal was filled, the post was inserted and positioning was verified (Figure 10).

Figure 11. Photo curing of cement.

It is essential to cover the head portion of the post with the cement to ensure adequate coating and maximize bond strength between the post and cement. The cement will auto-cure, but the trans-illumination of the post (due to unidirectional fibers) will allow light polymerization. This feature will ensure rapid and complete cement polymerization to the most apical portions of the canal, plus it will stabilize the post prior to core buildup. In this case the cement was cured en masse with the Coltolux LED curing light (Coltène/Whaledent) for 30 seconds (Figure 11).

Figure 12. Injecting core material into post.

The final step was to build up the core with the fiber-reinforced, dual-cured ParaCore material (Coltène/Whaledent). This fluoride-releasing, dentin-shaded material (building color from within) is packaged in an automix cartridge with a small dispensing tip. As be-fore, it was desirable to cover the post/cement mass with the core material to ensure maximum surface contact between the resin materials (Figure 12). The appropriate shape ParaForm (Coltène/

Whaledent) acts as a carrier and shape for the core material. After proper positioning of the shell, the excess core material was removed, and the mass was light-cured for 40 seconds as before.

With the foundation established, the preparation phase was undertaken. All-ceramic core crown systems require a 1.5-mm labial/incisal reduction and approximately 0.7-mm lingual reduction in the anterior zone. Due to the Procera aluminous core being only 0.4 mm in thickness, the ceramist is able to apply ample amounts of porcelain for aesthetics. It is necessary to establish a rounded shoulder finish line for the marginal configuration. The margin was placed slightly subgingival, and adequate ferrule concepts were employed.      

Figure 13. Injecting Magic FoamCord around prep.
Figure 14. Placement of Comprecap. Figure 15. Exposed margins of prep.

The impression step is extremely important to capture the details of the margins. This will ensure complete closure due to the accuracy of the Procera crown fabrication system. To aid in soft-tissue displacement Magic FoamCord (Coltène/Whaledent), which is an expanding PVS material, was employed to gently and cleanly displace the free gingival margins and open up the sulcus. The material is supplied in an automix cartridge and was injected around the marginal areas (Figure 13). The foam expansion was kept in check by placement of a small Compre Cap (Coltène/Whaledent), which was left in place and stabilized by having the patient bite into the cap for 3 minutes (Figure 14). After removal, one can plainly observe the margins due to the soft tissue being distended (Figure 15).

Figure 16. Injecting of lb Affinis impression material. Figure 17. Final impression of No. 7.

The impression must be taken immediately. The field should be dry and clean. The light-body PVS impression material (Affinis, Coltène/Whaledent) was chosen because of its flow characteristics, coating capabilities, and accuracy. This material was injected into the preparation via the Affinis automix cartridge and microdelivery system (Figure 16). To support the impression, the similar fast-set heavy-body version of Affinis was placed into a stock tray and allowed to polymerize for 2 minutes. After easy removal, the color contrast of the impression material made it evident that the margins had been captured (Figure 17).

Figure 18. Placement of provisional with TempoSil.

The final phase of this appointment was to construct the provisional crown. The method employed was to take the preoperative stone model, spray it with silicone, and form a putty matrix utilizing Affinis Putty Soft from teeth Nos. 6 to 8 as a keying index. The bis-acrylic resin material shade A3.5 of Cool Temp (Coltène/Whaledent) was in-jected into the mold and allowed to polymerize for 4 minutes over the prepared tooth. This class of materials shrinks very little for easy removal, and it is extremely durable. After finishing and polishing in the lab, it was seated with TempoSil (Coltène/Whaledent). This temporary cement composed of zinc oxide and siloxane was easily peeled off the temporary crown (Figure 18).

Figure 19. Poured up die model.

Finally, an opposing impression was made with Affinis monobody mixed with the Penta mixing machine (3M ESPE). After the models were poured, the die was trimmed and marked, and all relevant information was sent to the lab for fabrication of the Procera crown. With use of the new Forte scanner (Nobel Biocare), the margins were read and the coping design was established. It is extremely important to have a well-defined margin and accurate die to ensure the optimum fit of the crown on the prepared tooth (Figure 19).

Figure 20. Final placement of Procera crown.

After 2 weeks the crown was returned from the lab and inspected for fit and overall architecture. From an intraoral perspective the shade, margins, and occlusion were analyzed. Centric stops were verified, and lateral excursions were reviewed with red Accufilm articulating paper (Parkell). Once all criteria were checked, the abutment was cleaned with a slurry of pumice. The final cementation of this very aesthetic crown was accomplished using ParaCem, as described previously. After easy cleanup procedures, the entire fixture was light-cured as before for improved physical properties and immediate stabilization (Figure 20).

CONCLUSION

 

The proper integration of restorative materials offers biological harmony with hard and soft tissues. The chemistry and physics of similar materials act in synergy to promote retention and strength and offer excellent aesthetics. It is fortunate for clinicians, and especially patients, that we have predictable materials available for aesthetic restorative dentistry.



Dr. Braun maintains a full-time specialty practice in prosthodontics located in Saginaw, Mich. He lectures throughout the country and internationally on the very latest dental technologies, equipment, and materials relating to aesthetic restorative dentistry. He can be reached at (989) 793-5551 or jbraundds@ aol.com.