Written by Martin G. Abel, DDS Monday, 30 November 2009 19:00
Crown and bridgework has been the mainstay for replacing missing teeth for decades. From gold and pyroplast facings, Steele (flatback) facings and porcelain-fused-to-gold, to the introduction of CAD/CAM metal-free bridges in recent years, we have seen developments that allow the delivery of both functional and aesthetic restorations. Of course, implants are becoming standard of care, but quite a few patients are fearful of the technique and/or may desire a more rapid “fix” for their missing teeth. There are circumstances whereby traditional bridges may not be the best treatment. Patients with periodontal issues who still want to preserve their teeth, and not have extractions and implants, do have other options.
With traditional bridgework, we prepare, impress, have the restoration fabricated, and then deliver it using a permanent luting cement. The usual thought during and after the placement process is that the bridgework will not move nor “fall out.” However, what are the options for our patients with periodontal disease, or perhaps “external root resorption problems,” who then need treatment on one or more of the abutments? Removal of the bridge often results in its destruction and the need for it to be remade. This can be very expensive for the patient.
A Description of the Technique
The technique for these procedures is very much the same as for traditional bridgework. The patient is seated, options for treatment and reasons for each are discussed, following the ABCs of informed consent:
A. discuss options of treatment
B. discuss the benefits of each treatment
C. discuss the complications and risks of treatment.
When telescopic bridges are selected as the treatment of choice, alginate impressions are taken and study models are constructed. Vacuum formed trays are then made from the diagnostic models to facilitate the construction of a temporary bridge after the preparations are completed. The preparations may be slightly more aggressive than with traditional design, because we need approximately 0.3 mm extra space circumferentially for the telescopic copings. The preparations may be a deep chamfer or a shoulder-bevel combination. The margins may be placed supra- or subgingivally, depending upon the patient’s aesthetic requirements and the dental/gingival morphology. Retraction cord is placed and a final vinyl polysiloxane (VPS) impression is taken. (Full-arch trays and impressions are recommended.) When only one arch is involved, an opposing arch impression is taken with alginate, or another suitable material. The bite registration is then acquired with a rapid set material, and everything is sent to the dental laboratory with the proper prescription and instructions.
The dental laboratory technicians construct the telescopic copings with high-noble metal (one telescopic coping for each abutment tooth), and send the case back to the dental office. The provisionals are then removed, the preparations cleaned with pumice and rubber cup, and the telescopes are tried-in on the abutment teeth. Radiographs are taken to ensure correct fit of the telescopic copings. Finally, the copings are delivered with an appropriate permanent cement.
A new impression is then taken with the telescopic copings in place, and a new bite registration is also secured. At this point, the vacuum formed provisional splint is brought in and trimmed to fit. The temporization material of choice, bis-acrylic composite, is dispensed into the vacuum formed tray, then placed intraorally with gentle pressure to ensure no voids or bubbles are incorporated into the appliance. The tray is left for enough time to allow initial set, and then gently removed. It is replaced several times to ensure correct fit with no distortion. After the provisional is set, trimming and finishing are done with carbide finishing burs and discs. The provisional is tried-in again, the occlusion adjusted, and then polished and cemented with temporary cement. The dental laboratory technicians will then make a bridge framework, and another try-in appointment will be used to verify proper fit. Finally, the porcelain is added, and the completed restoration is cemented in the mouth with a provisional cement.
Benefits of Telescopic Technique
In the event of one or more of the abutments becoming postoperatively involved, thus requiring extraction, the dentist can carefully remove the bridge, remove the offending tooth, and re-cement after filling the residual opening. The patient doesn’t have to have a replacement bridge constructed. In this way, money, time, and patient discomfort have been minimized.
Figure 1. The veneers before treatment. (Note the gingival levels.)
Figure 2. The preoperative smile.
Our patient desired a very white “Hollywood smile” (Figures 1 and 2). He had resin-bonded splints (upper and lower) which, because of periodontal issues, were constantly breaking. He also had porcelain veneers on his anterior teeth. In addition, he complained of discomfort to his tongue due to the splints.
Figure 3. A gingivoplasty is done using electrosurgery unit.(Dento-Surge [Ellman]).
Figure 4. An image of the upper preparations.
Figure 5. The upper provisional (Luxatemp [DMG America]) in place in the vacuum formed tray.
Figure 6. The preparations.
Figure 7. The telescopic copings in place.
|Figure 8. The final restorations.|
We began by anesthetizing both the upper and lower arches. Impressions were taken of both arches, to be used to construct vacuum formed provisional splints. Gingival recontouring was performed using the Dento-Surge (Ellman) eletrosurgery unit, set at cut.coag level 7 (Figure 3).
I attempted to achieve a more cosmetically acceptable gingival architecture following anatomical guidelines. Preparations were completed (16 teeth) and each then were checked carefully for parallelism (Figures 4 to 6). (As mentioned previously, shoulder-bevel or deep chamfer preparations will work for this technique.)
Retraction cord was placed and VPS (Virtual [Ivoclar Vivadent]) final upper/lower impressions were taken. The bite registration was taken with a fast set VPS bite registration material (Flexitime Bite [Heraeus Kulzer]). To construct the provisionals, Luxatemp (DMG America) was dispensed into the prefabricated vacuum formed trays. Next, the trays were placed over the prepared teeth (Figure 5). After waiting until the material reached initial set, the trays were removed from the mouth and checked for fit and integrity. After placing and removing the provisionals several times to ensure a passive fit, the vacuum formed tray was removed and the trimming process was begun using ultrafine diamonds and ET-type carbide finishing burs (7901-FSQ carbide, [Komet USA]). The dental technicians fabricated telescopes and returned them to our office for installation (Figure 7).
The telescopic copings were individually checked for fit and then cemented in with a strong resin cement (Permacem [DMG America]). A new impression was taken with the telescopic copings in place and sent to the dental laboratory. The dental technicians constructed the final restorations and returned them to our office. They were cemented in with a temporary cement (Figure 8). In the event that any of the abutment teeth become involved and subsequently need extraction, the final bridge can be carefully recovered and the offending tooth extracted. Then, the bridge can be easily cleaned out and recemented with a provisional cement, such as TempBond (Kerr), or Systemp.link (Ivoclar Vivadent).
Patients who have periodontal problems, external root resorption issues, or even a high caries index are candidates for the telescopic bridge technique. This treatment protocol minimizes the risk of damage of adjacent teeth, and the bridge itself, if it needs to be removed for subsequent dental treatment.
Disclosure: Dr. Abel repoorts no conflicts of interest.
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