Telescopic crowns were initially introduced asretainers for removable partial dentures (RPDs) at thebeginning of the 20th century. They are also known asa double crown, crown and sleeve coping (CSC), or asKonuskrone, a German term that described a cone-shaped design. These crowns consist of an inner or pri-mary telescopic coping, permanently cemented to anabutment, and a congruent detachable outer or sec-ondary telescopic crown, rigidly connected to adetachable prosthesis. Copings were designed to pro-tect the abutment from dental caries and thermal irri-tations and also provided retention and stabilization ofthe secondary crown. The secondary crown engagesthe primary coping to form a telescopic unit and servesas an anchor for the remainder of the dentition.

The tapered configuration of the contacting wallsgenerates a compressive intersurface tension based onwedging action. This concept has been widely used inengineering for rapid and secure fastening of 2 con-gruent mechanical parts. Tension should be sufficient-ly strong to sustain the RPD in place. In restorationsinvolving the entire dental arch, retentive and stabiliz-ing properties of telescopic retainers are directly relat-ed to their number, angle of wall taper, and harmo-nious distribution along the dental arch.

The average wall taper commonly has a 6-degreeangle.1,2 Tapering of the coping walls reduces reten-tion between the unit elements. The smaller thedegree of the taper, the greater the frictional retentionof the retainer.2 If the extent of intersurface contactbetween both components is restricted by limitedabutment height, a reduced angulation, between 2 to5 degrees per side, should be used to improve reten-tion. The splinting action of telescopic restorationsoccurs when multiple outer and fixed inner telescopiccrowns engage each other in situ. Elements of splint-ing and support are not affected by the degree of wallangulation. Taper of the walls of the primary copingcan be adjusted to a predetermined angle, according tospecial requirements of each patient. They are milledto exact configurations of taper angles of the walls with

each other to create a common path of insertion forouter telescopic crowns of a retrievable superstructure.

Although an apparently antiquated method oftreatment, telescope retained dentures, if appropriate-ly applied, have remained a refined and effectiveprosthodontic solution for selected complex patienttreatments that require unique clinical and technicalskills.3-5

CLINICAL CONSIDERATIONS

Telescopic crowns have been used mainly in RPDsto connect dentures to the remaining dentition,1-3 butthey may also be designated as retainers in totally abut-ment-borne detachable prostheses.4 The term detach-able was preferred to removable in the context of thisarticle to avoid confusion with RPDs that receive theirsupport partly from abutments and partly frommucoperiosteal structures.

Telescopic-anchored prostheses are functionallycomparable with conventional fixed partial dentures(FPDs) and are considered to be a most effectivereplacement for lost teeth and are well tolerated psy-chologically. The distribution of abutments for detach-able prostheses should conform to principles that gov-ern fabrication of FPDs. Accordingly, detachable pros-theses are usually indicated only for patients withmultiple abutments distributed bilaterally in strategicpositions along the dental arch.

Telescopic crowns have also been used successfullyin RPDs and FPDs supported by endosseous implantsin combination with natural teeth,5 including over-dentures.6,7 The primary advantage of a telescopicprosthesis is retrievability. If the remaining dentition isin a state of transition, abutments splinted with FPDscan be a problem. A telescopic prosthesis is a more ver-satile alternative for these patients because the pros-thesis can be repaired without reconstruction of theentire superstructure, despite a localized failure.

The patient can disengage telescopic restorationwith dislodgment of the outer telescopic crowns fromtheir copings. The patient should be instructed on pre-cautions to prevent damage to the denture duringcleaning because distortion of an outer telescopiccrown can render the prosthesis nonfunctional. Therehas been ample evidence that telescopic dentures pro-mote oral hygiene and periodontal health because theabutments are more accessible for oral hygiene. In

Tooth-supported telescopic prostheses in compromised dentitions: A clinical report

Yair Langer, DMD,a and Anselm Langer, DMDb

The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, andHebrew University-Hadassah Faculty of Dental Medicine, Jerusalem, Israel

aInstructor, Postgraduate Program, Department of Prosthetic Den-tistry, The Maurice and Gabriela Goldschleger School of DentalMedicine, Tel Aviv University.

bProfessor Emeritus, Department of Prosthodontics, Hebrew Uni-versity-Hadassah Faculty of Dental Medicine.

J Prosthet Dent 2000;84:129-32.

AUGUST 2000 THE JOURNAL OF PROSTHETIC DENTISTRY 129

addition, peripheral gingival margins and the prosthesiscan be readily cleaned after removal from the mouth.2,8

The splinting effect of a telescopic superstructure issimilar to an FPD and has a favorable influence on sta-bilization of the remaining dentition and improvesperiodontal health. This clinical report describes the

clinical and technical aspects of using telescopiccrowns in the restorative treatment of 2 patients.

CLINICAL REPORTPatient 1

The indication for detachable prosthesis is illustratedby a clinical condition of a middle-aged woman (Figs.1 and 2) who wished to retain her remaining maxillaryteeth. The patient was extremely reluctant to have anRPD. Splinting the remaining teeth was indicated toachieve stabilization against occlusal stress. The prog-nosis of the periodontally compromised abutmentsremained guarded, making immobilization with a fixedrestoration a high risk to the patient. The patient wascounseled on the treatment options and chose to receivetreatment with a detachable telescopic prosthesis.

The hopelessly compromised right second premolarand left central incisor were extracted. The remainingmaxillary teeth were prepared. Primary telescopic cop-ings were fabricated and cemented to the remainingteeth from the left second molar to the right first pre-molar (Fig. 3) after preprosthodontic/periodontictreatments, including provisionalization for the dura-

THE JOURNAL OF PROSTHETIC DENTISTRY LANGER AND LANGER

130 VOLUME 84 NUMBER 2

Fig. 1. Radiographs for patient 1 before treatment.

Fig. 2. Fixed provisional restoration that includes all avail-able maxillary abutments in situ.

Fig. 3. Primary copings cemented to all abutments.

Fig. 4. Gingival view of detachable telescopic superstructure.

Fig. 5. Telescopic prosthesis.

tion of the follow-up period (Fig. 2). A definitive,removable telescopic prosthesis, which included 8outer telescopic crowns and 3 pontics (including a leftmolar, central incisor, and a right cantilever premolar),was then made (Figs. 4 and 5). Oral hygiene regimenswere maintained during the course of treatment and thepatient received instructions in meticulous home care. Astrict 3-month recall regimen was recommended.

Patient 2

A 65-year-old patient was previously treated with across-arch FPD that connected the remaining 7endodontically treated mandibular teeth (Fig. 6). Themaxillary arch was restored with a fixed restorationthat was supported and retained by 4 endosseousimplants (Figs. 6 and 7). Mandibular abutments werejudged to be too short to provide sufficient retentionfor crowns and FPDs (Fig. 7). The endodonticallytreated roots posed a latent risk for an irretrievablecemented prosthesis, so a detachable telescopicrestoration was selected as an alternate solution. Theavailable mandibular abutments were provided with

primary copings (Fig. 8). A near parallel 2-degreetaper was selected to ensure frictional retentionbetween the primary and secondary artificial crowns(Fig. 8). The detachable superstructure was comprisedof 7 veneered secondary crowns and 6 pontics that

LANGER AND LANGER THE JOURNAL OF PROSTHETIC DENTISTRY

AUGUST 2000 131

Fig. 6. Panoramic radiograph of patient 2 before treatment.

Fig. 7. Faulty mandibular FPD and maxillary implant-sup-ported and retained FPD (pretreatment).

Fig. 8. All available mandibular abutments provided withprimary copings.

Fig. 9. Gingival view of detachable telescopic superstructure.

Fig. 10. Mandibular telescopic prosthesis in occlusion withimplant-bar-splint–supported and –retained maxillary over-denture.

included a right premolar-shaped cantilever (Figs. 9and 10). The maxillary jaw was treated with a bar-splint–retained and –supported overdenture on the 4dental implants (Fig. 10).

SUMMARY

This article describes indications for treatment withtelescopic restorations on patients with periodontallyand endodontically compromised dentitions thatrequire splinting, with special emphasis on treatmentthat restores the entire dental arch. Stabilization ofcompromised teeth with fixed splinted restorations isusually inadvisable because of the risk factors involved,such as eventual localized abutment failure.

Detachable telescopic prostheses may be preferredas a near equivalent or substitute because they can bedetached and repaired without reconstruction of theentire restoration. Retentive and splinting propertiesof detachable telescopic restorations can be as effectiveas FPDs. Inner telescopic copings can be cemented asindividual crowns to facilitate the procedure. Tele-scopic restorations can be retrieved by the patient forcleaning and easy access to the entire marginal peri-odontal circumference of the abutments. This pro-motes effective home care and oral hygiene. In addi-tion, principles of design and indications, as well astechnical and clinical factors, were discussed.

REFERENCES

1. Langer A. Telescope retainers for removable partial dentures. J ProsthetDent 1981;45:37-43.

2. Langer A. Telescope retainers and their clinical application. J ProsthetDent 1980;44:516-22.

3. Sethi A, Sochor P. Restoration of the maxillary arch using implants, nat-ural teeth and the Konus crown. Dent Update 1994;21:52-5.

4. Langer A. Tooth-supported telescope restorations. J Prosthet Dent1981;45:515-20.

5. Laufer BZ, Gross M. Splinting osseointegrated implants and natural teethin rehabilitation of partially edentulous patients. Part II: principles andapplications. J Oral Rehabil 1998;25:69-80.

6. Besimo C, Graber G. A new concept of overdentures with telescopecrowns on osseointegrated implants. Int J Periodontics Restorative Dent1994;14:486-95.

7. Besimo C, Graber G, Schaffner T. Hybrid prosthetic implant supportedsuprastructures in edentulous mandible. Conus crowns and shell-pin-systems on HA-Ti-Implants: part 2. Prosthetic construction principles.ZWR 1991;100:70-6.

8. Hou GL, Tsai CC, Weisgold AS. Periodontal and prosthetic therapy inseverely advanced periodontitis by the use of the crown sleeve copingtelescope denture. A longitudinal case report. Aust Dent J1997;42:169-74.

Reprint requests to:DR YAIR LANGER

DEPARTMENT OF PROSTHETIC DENTISTRY

MAURICE AND GABRIELA GOLDSCHLEGER SCHOOL

OF DENTAL MEDICINE

TEL AVIV UNIVERSITY

TEL AVIV 69978ISRAELFAX: 972-3-6409250E-MAIL: edek@inter.net.il

Copyright © 2000 by The Editorial Council of The Journal of ProstheticDentistry.

0022-3913/2000/$12.00 + 0. 10/1/108026

doi:10.1067/mpr.2000.108026

THE JOURNAL OF PROSTHETIC DENTISTRY LANGER AND LANGER

132 VOLUME 84 NUMBER 2