Old School Meets New School by John Nosti, DMD, FAGD, FACE, FICOI

One would have to agree that in the past 20 years the advancements in implant dentistry have allowed us to significantly change the quality of our patients’ lives.

Educational institutions have changed their curriculums to include both the surgical and prosthetic techniques of implant dentistry to remain current and competitive. Sadly, many of our older prosthodontic techniques are now being taught less frequently in schools in favor of their implant counterparts, and are thus becoming lost art forms.

The patient ultimately suffers when implants are not a clinical solution or are financially too far out of reach. Stress breakers and precision attachments, once commonly fabricated, are no longer prescribed. It’s time to reinvent some of these lost art forms and techniques with materials readily available to us.

An extremely underutilized technique is the use of telescopic copings in fixed and removable prostheses. The use of gold copings was first introduced as a fixed partial denture retainer at the beginning of the 20th century.¹ It was not until the 1950s, however, when the concept of the telescopic coping was reported to overcome the problem of abutment parallelism during the fabrication of fixed partial dentures.

Telescopic copings
The telescopic or primary coping concept was then successfully applied in extensive prosthodontic treatments for periodontally compromised patients for many years—until the advent of dental implants.^3–14

The telescopic crown is defined as an artificial crown fabricated to fit over a coping.¹⁵

“Each primary coping is usually fabricated parallel to the adjacent copings with an average wall taper of a 6-degree angle of convergence. The copings are definitively cemented to abutment teeth, and then a fixed prosthesis as a secondary structure is fabricated over the copings and placed with different types of cements or medium.”¹⁶

• 

  Figure 1

• 

  Figure 2

• 

  Figure 3

Dr. James D. Weaver outlined a series of three advantages and disadvantages of telescopic prostheses in one study. The primary advantages he outlined include:

1. Excellent fit of copings to the prepared teeth may reduce the possibility of recurrent caries on the abutment teeth when a long-span fixed partial denture is fabricated, or when abutment teeth have different degrees of mobility. We’ve all seen cases of long-span bridgework start to fail because of recurrent caries on an opened margin (Fig. 1).
2. Aligning abutments for the fabrication of a fixed partial denture without over-reducing tooth structure. This is one of the most difficult challenges when dealing with multi-abutments with long-span bridgework (Fig. 2).
3. Potential ability to retrieve superstructure, which is usually placed on the copings with provisional medium (temporary cement). This feature may allow removal of the superstructure when there is a need for additional periodontal or endodontic therapy, extraction of failed abutments, or implant placement after the completion of prosthodontic treatment (Fig. 3).

Furthermore, Weaver added additional advantages to telescopic copings due, in part, to the dental materials readily available to date.

• 

  Figure 4

• 

  Figure 5

• 

  Figure 6

Correction copings may be used in aesthetic cases where one must deal with a dark preparation (Fig. 4). The correction coping can be fabricated of an opaque ingot that blocks out the dark preparation. This coping can then be externally stained to match either the adjacent preparation or adjacent tooth structure. (Details about this procedure appear later in this article.)

Another advantage of these copings can be found in large-span bridge work with the presence of a pier abutment. A pier abutment, also known as an intermediate abutment, is a natural tooth between terminal abutments that serves to support a fixed or removable dental prosthesis. A typical example is when the patient is missing the maxillary first molar and maxillary first premolar on the same side. The maxillary second premolar is the pier abutment between the canine and the second molar¹⁵ (Fig. 5). A pier abutment requires a nonrigid connector if it’s going to be restored with a fixed prosthesis

Disadvantages
Telescopic copings presented some disadvantages that limited their uses to specific clinical situations:

• Fabricating copings and superstructure involves more complex laboratory and clinical procedures, such as additional casting and clinical remounting.
• Laboratory costs and treatment fees are generally increased, and thus the restorative treatment plan will have a higher cost for the dentist to cover these fees.
• In the past, the use of the conventional telescopic prosthesis may not have been recommended when there was a high aesthetic demand, because the copings were traditionally fabricated from a gold or similar alloy.
• It may be difficult to place both the gold collar of the coping and the metal margin of the superstructure subgingivally if a patient presents with high lip line at smile and thin, delicate gingival tissue around anterior abutment teeth. This gingival tissue biotype is more prone to recession, possibly caused by prosthodontic procedures such as tooth preparation and impression making^16–20 (Fig. 6).

Advantage: lithium disilicate
Previous studies and articles have used porcelain or zirconia copings to manage the obvious disadvantages in aesthetic cases.^16,20,21 This article will demonstrate the use of E.max (lithium disilicate, Ivoclar Vivadent) copings and discuss its advantages over traditional gold and zirconia copings.

Handling a dark preparation: Many of us have had the aesthetic case of two or more anterior aesthetic restorations where one of the teeth has a dark preparation. (Figs. 4 and 7). Typically, a dark preparation is handled by using an opaque restorative medium such as a porcelain fused to metal or zirconia crown.

The issue becomes that the opaque restorative materials tend to be slightly higher in value and offer less natural fluo­rescence than adjacent natural teeth or restorations. The treating practitioner is typically forced to make one, both or all restorations more opaque to compensate for the dark preparation.

The result can be an aesthetic failure. In the case where one or two teeth were treated, these restorations will not match the adjacent natural teeth in value and will appear brighter than the adjacent natural teeth. In the case of a cosmetic smile design the restorations will all be of a higher value, and the added opacity or brighter appearance can result in an artificial appearance.

The solution is to fabricate an E.max correction coping, which can be made of an opaque ingot, to block out the underlying dark preparation. The coping is then externally stained to match the adjacent, normal preparation (Fig. 8).

The telescopic crown can then be made of the same ingot as the adjacent crown’s. This provides several benefits over gold or zirconia copings. One, it allows the practitioner complete control of value by utilizing warming (lower value) or brightening (higher value) try in pastes and cements.

Secondly, considering that the coping is being used as a block-out medium and not being used as a stress-breaker, the coping can be bonded to the tooth using a total-etch technique (recommended because the coping is typically less than 1.5 millimeters thick), as well as the ability to bond the E.max coping to the E.max crown. Lastly, the telescopic crown allows practitioners to use one cement for the entire case, rather than multiple materials, as was recommended in traditional coping cases.

• 

  Figure 7

• 

  Figure 8

• 

  Figure 9

• 

  Figure 10

Walkthroughs
The first steps are to bond the E.max coping to the tooth and to choose the correct value of cure cement to bond the crown to the coping and adjacent restorations to the natural teeth. Next, while the adjacent teeth will be treated with phosphoric acid, the coping can be treated with Monobond Etch and Prime (Ivoclar Vivadent), which has received FDA clearance for intraoral use as a safe alternative for hydrofluoric acid.

The bonding agent can then be placed and polymerized on the adjacent teeth only. This means waiting to place the bonding agent on the coping until just before pla­cing the restorations loaded with cement. The cement and bonding agent between the correction coping and the crown is polymerized using the sandwich technique.

The result is an aesthetic, all-ceramic smile with the block-out result of a metal coping (Figs. 9 and 10).

Conclusion
Telescopic copings have proven to be a viable alternative for implant prosthetics in cosmetic cases without the limitations it once had in the past. They can also be considered a first-line treatment option in cases when handling dark preparations. With these added treatment alternatives, dentists can now provide a time-tested, predictable, long-term outcome with the benefit of new age cosmetics.

References
1. Peeso FA. Crown and bridgework for students and practitioners. Philadelphia: Lea & Febiger Co; 1916. p. 480. J Prosthet Dent. 2004 Sep;92(3):220-3.
2. Steinberg GJ. The telescopic type of fixed partial denture abutment. J Prosthet Dent 1959; 9:863-6.
3. Prichard J, Feder M. A modern adaptation of the telescopic principle in periodontal prosthesis. J Periodontal 1962; 33:360-4.
4. Yuodelis RA, Faucher R. Long-term stabilization. In: Schluger S, Yuodelis R, Page RC, Johnson RH. Periodontal diseases: Basic phenomena, clinical management, and occlusal and restorative interrelationships. 2nd ed. Philadelphia: Lea & Febiger; 1990. p. 672-
5. Amsterdam M, Abrams L. Periodontal prosthesis. In: Goldman H, Cohen DW. Periodontal therapy. 5th ed. St Louis: CV Mosby Co, 1968;1001-4.
6. Amsterdam M. Periodontal prosthesis. Twenty-five years in retrospect. Alpha Omegan 1974; 67:8-52.
7. Berman H, Lustig LP. Primary substructures and removable telescopic superstructures in dental reconstruction. J PROSTHET DENT 1960; 10:724-32.
8. Prichard J, Feder M. A modern adaptation of the telescopic principle in periodontal prosthesis. J Periodontal 1962; 33:360-4.
9. Endo SS. The use of the telescopic crown. NACDL 1970; 17:9-15.
10. Talkov L. Lining up multiple abutments. J Prosthet Dent 1951; 1:727-32.
11. Gordon T. Telescopic reconstruction, an approach to oral rehabilitation. J Am Dent Assoc 1966; 72:97-105.
12. Steinberg GJ. The telescopic type of fixed partial denture abutment. J Prosthet Dent 1959; 9:863-6.
13. Schluger S, Yuodehs R, Page R. Periodontal disease. Philadelphia: Lea & Febiger Co, 1977;678-82.
14. Pugh CE, Smerke JW. Rationale for fixed prostheses in the management of advanced periodontal disease. Dent Clin North Am 1969; 13:243-62. 15. The Glossary of Prosthodontic Terms. J Prosthet Dent 1999; 81:102.
16. Fixed partial denture supported by all-ceramic copings: a clinical report. Pellecchia R1, Kang KH, Hirayama H.
17. Weaver JD. Telescopic copings in restorative dentistry. J Prosthet Dent 1989; 61:429-33.
18. Parikh et al. Precisive Means to Manage Pier Abutments. European Journal of Dental Therapy and Research, 2013:3:160-166 166
19. Becker W, Ochsenbein C, Tibbetts L, Becker BE. Alveolar bone anatomic profiles as measured from dry skulls. Clinical ramifica-tions. J Clin Periodontal 1997; 24:727-31.
20. Sanavi F, Weisgold AS, Rose LF. Biologic width and its relation to periodontal biotypes. J Esthet Dent 1998; 10:157-63.
21. Uludag B1, Sahin V, Ozturk O Fabrication of zirconium primary copings to provide retention for a mandibular telescopic overden-ture: a clinical report. Int J Prosthodont. 2008 Nov-Dec;21(6):509-10.
22. Groesser J, Sachs Philipp, C et. al Clinical Oral Investigations May 2014, Volume 18, Issue 4, pp 1173–1179 Retention forces of 14-unit zirconia telescopic prostheses with six double crowns made from zirconia—an in vitro study.
23. Misch, CE: Dental Implant Prosthetics, Ed 2., St. Louis, 2015. CV Mosby/Elsevier.

Support these advertisers included in the May 2017 print edition of Dentaltown magazine.

Click here for an entire list of supporters.