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Telescope retainers for removable partial dentures
Telescope retainers for removable partial dentures Anselm Langer, D. M. D. * Hebrew
University-Hadassah
Faculty
of Dental
Medicine,
R
emovable partial prostheses are borne partly by the remaining dentition and partly by the mucoperiosteal tissues. These dentures are usually supported and retained with clasps, precision, or semiprecision attachments. An effective type of retainer, possessing retention, support, and a splinting action between multiple abutment teeth, is a double crown known as the telescope retainer.‘. ’ The primary coping of this retainer unit is cemented to the abutment tooth. The secondary crown, which is made to fit and to be held in position by intersurface tension, is rigidly connected with the removable superstructure. In restorations containing two or more telescope crowns, the superstructure acts as a rigid splint when in position, interlocking the primary and secondary parts to act as a functional unit (Fig. 1). Telescope crowns have proven more effective than other direct retainers.:’ Their degree of retention can be planned to suit different situations by modifying the design. The amount of intersurface friction depends on the configuration of the taper angle and area of surface contact. Telescope crowns can also be used as indirect retainers to prevent dislodgement of the distal extension base away from the edentulous ridge. The resistance to this movement is built-in in rigid telescope retainers with cylindrical or conical primary copings designed with no free space between both components. One of the main advantages of telescope retainers is that, being pericoronal devices, they transmit the occlusal forces in the direction of the long axes of the abutment teeth (Fig. 1). This has proven to be the least damaging application force. Lateral forces exert traumatic pressure on the abutments.‘.”
*Associate Professor
and Head,
Department
+ 07900.70/00
1981 The
of Oral
Rehabilita-
tion.
0022-3913/81/010037
C. V. Moshy
Co.
Jerusalem,
Israel
RIGID AND RESILIENT PARTIAL DENTURES
TELESCOPED
There is a controversy in distal-extension partial dentures, whether to rigidly attach the denture to the abutment teeth or to interpose resilient stress-breaking elements between them, reducing the transfer of traumatic forces from the denture to the teeth. Hence, modifications have been introduced to provide freedom of rotation between the primary and secondary crowns, building the stress-breaking principle into the retainer itself.’ The concept of a resilient removable denture seems to be generally accepted where only a small number of teeth are left for supportY Hofmann and Ludwig,“’ for a period of 2 years, observed 72 patients with dentures built over abutments with telescope crowns. These were adjusted to provide a mucosal resiliency factor of 0.2 to 0.5 mm. In all patients, no more than three abutment teeth were left in the restored arches. Hofmann and Ludwig found that most of the teeth were stable during the first 2 years of use. With time, mobility did increase at a creeping rate, and four teeth had to be extracted during the period. Yalisove’ ’ and Yalisove and Dietz” used crown and sleeve coping telescope retainers with a conical taper configuration, irrespective of the number of abutments. The gingival third of the copings contained a 0.003 to 0.010 inch space between the sleeves and crowns, allowing for rotation of the secondary crowns anchored in their denture. This design eliminated the frictional retention of the denture without impairing the splinting action. When a lateral force was exerted on one side of the arch, the stress was properly redistributed to the rest of the abutments and to the other side. E. Koerber’:’ used the rigid telescope denture when possible, but favored a resilient prosthesis when the small number of remaining teeth and their distribu-
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
37
Fig.
1. Superstructure containing the secondary crowns (SC), is a telescope restoration, acting as a rigid splint to interlock the secondary and primary crowns (PC). The telescope retainer transfers the occlusal forces in the direction of long axes of the abutment teeth (arrows).
Fig. 4. Two canine and three premolar primary copings cemented in place.
Fig. 5. Tissue surface of the removable bilateral dist& Fig, 2. Before treatment. Patient needs a complete maxillary denture and a removable bilateral distal-extension mandibular partial denture.
extension partial denture. Secondary crowns, splinted on one side with pontic (arrow) and soldered together on the other side, are rigidly attached to the distal extensions The rigid sublingual bar connector provides bilateral splinting to the abutments.
Fig. 3. Old dove1 crowns (Richmond) on premolars and canines, prepared for inner copings.
38
Fig. 6. Completed restoration in the mouth.
JANUARY
1981
VOLUME
45
NUMBER
1
TELESCOPE
RETAINERS
Fig. 7. Before treatment. Maxillary remade. A unilateral distal-extension indicated.
crowns must be partial denture is
Fig. 9. Abutment
big.
Fig. 8. Teeth after removal of crowns.
tion justified it. K. H. Koerber’-’ felt that the rigid telescope denture is healthier, prolonging the life of the abutment. When all occlusal factors are considered, this principle seems to have a prophylactic effect on the rest of the dentition. Intense functional stimulation to the periodontal tissues of the abutment teeth causes a reactive adaptation following the resorption of the bone support under the denture-base extension. Indeed, clinical experience suggests that taking advantage of periodontal tooth support and relying less on mucoperiosteal support ensures better function and longer preservation of the dental arch.‘“. I’ The insertion of stress-bearing elements into the retainer construction or their interposition between the abutments and mucosally borne parts of the removable superstructure may reduce the total load transmitted to the abutment teeth and prolong their
THE JOURNAL
OF PROSTHETIC
DENTISTRY
10.
Milled,
teeth built up with post cores.
shoulderiess,
cemented to all maxillary
cone-shapea
copings
are
abutment teeth.
survival. On the other hand, the soft supporting tissues may receive the occlusal forces so that the denture may be depressed following traumatic bone resorption. Therefore, the stability of occlusal harmony cannot be maintained very long as the natural teeth come into premature contacts with their antagonists. When using a rigid-type telescope denture, it is important to secure maximal extension of denture base coverage, similar to that used in complete denture techniques. CLINICAL
APPLICATIONS
The best way to preserve the stability and efficiency of the dental arch, whenever enough tooth support is available, is to use a rigidly constructed removable partial denture. One example is the bilateral distal-extension
39
Fig. 11. Fit of splinted secondary crowns is checked in the mouth.
Fig. 12. Tissue surface of the completed restoration. Secondary crowns are an integral part of the superstructure. Rigid palatal connector ensures the abutments a bilateral group action.
Fig. 13. Completed restoration in place.
40
Fig. 14. In a traffic accident, the patient lost the entiw segment of anterior teeth and three premolars.
Fig. 15. Teeth prepared for inner copings.
(Kennedy I) restoration. Cross-arch splinting is nrc‘essary to lend bilateral support? and stability is secured by soldering together secondary crowns ad.jacent to the edentulous spaces (Figs. :! through 6). Because of advanced periodontal disease. the USC of multiple abutments was indicated after some severely affected mandibular teeth bvere extracted and the remaining teeth were treated periodontallv. All maxillary teeth had to be extracted and an immediate denture made. An alternative solution may also bc considered. composed of two unilateral three-unit fixed partial dentures, extending from the canines to the second premolars, with rigid T-type precision attachments built into the second premolars or using clasps for anchorage. Because of the relatively small contact surfaces between the attachment and receptacle
JANUARY
1981
VOLUME
1s
NUhlBER
I
TELESCOPE
RETAINERS
Fig.
16.
Milled copings on the cast.
Fig. 17. Cast gold superstructure is a one-piece unit containing soldered secondary crowns and a retention frame for the denture base. components of the T-type precision attachments, they tend to wear out in distal-extension partial dentures in time, loosing their stabilizing and crossarch splinting action. Thus, the retentive and supporting advantages of the attachments and cast clasps are questionable in the long run. The large surface contact of parallel walls in the double crowns ensures good direct and indirect retention, cross-arch stabilization, and support of the distal extension of denture bases obtained by a functional closed mouth impression of the mucosal denture support area. One additional advantage of telescope retainers over precision attachments and clasps is their more axial transfer of occlusal load that produces less rotational torque upon abutment teeth. A second example is a unilateral distal extension (Kennedy II) restoration where leverage exerted by
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 18. Tissue surface finished superstructure base coverage.
has broad
Fig. 19. Finished restoration on the cast. the distal extension of the removable denture is significantly reduced by multiple abutment splinting. A good result could have been expected without including all maxillary teeth in the construction. However, since all the teeth needed crown restorations, they were included in the prosthodontic construction (Figs. 7 to 9). In the course of treatment, the conical double crown design was chosen (Fig. lo).’ To ease the insertion of the secondary crowns, the occlusal edges of the primary copings were bevelled at slant angles. For the sake of continuity and rigidity of the anterior removable splint, a pontic was included to replace the missing right lateral incisor. In this solution, the occlusal forces are distributed evenly among all remaining teeth in a favorable direction to their long axes. The close fit between the primary and secondary crowns ensures
41
Fig. 20. Cemented inner copings in the mouth.
Fig. 22. Arrow points to cement exposure caused by wear after 7 years. Telescope unit had to be remade. had to be replaced because of the wear of the gold on the occlusal surface, exposing cement (Fig. 22). Except for this and occasional base relining, the situation remained stable. SUMMARY
Fig. 21. Completed
prosthesis in the mouth.
the entire restoration a high degree of retention, stability, and ,joint group action of the splinted individual abutments (Figs. 11 to 13). A third restoration (Kennedy IV) involves a young patient who lost his mandibular anterior teeth, three premolars, and extensive alveolar bone in a traffic accident (Fig. 14). The shortness of the posterior teeth made any kind of intracoronal precision attachments impossible (Fig. 15). Because of the patient’s age, should cast clasps have been used, the abutment teeth would have had to be covered with crowns for protection against caries. Such clasps would not be esthetic nor would they have good mechanical qualities. Since the teeth needed to be prepared for crowns, telescope retainers were used (Figs. 16 and 17). A functional impression was made with an individual acrylic resin base attached to the gold framework (Fig. 18). A removable denture, based upon six telescope retainers was constructed in the course of treatment (Figs. 19 through 21). During a 12-year follow-up period, two of the telescope units
42
Telescope crowns used in removable partial dentures reduce the destructive horizontal and rotational occlusal forces by directing them more axially and less traumatically than other retainers. These properties are combined with excellent conditions for cross-arch and multiple abutment splinting. If one of the abutment teeth needs extracting, the denture can be repaired with acrylic resin simply by remaking the secondary crown into a pontic. The single copings can be easily cleaned due to the good accessibility around their gingival margins. They also protect the abutment teeth against caries and thermal irritation. Soldering of the primary copings or their connection with accessory bars is not necessary in rigidly constructed telescope crowns, because the secondary crowns incorporated in the superstructure provide sufficient rigidity. In addition, the splinted copings gingival hyperplasia often cause inflammatory because the solder joints are too close to the gingival margins, preventing proper hygiene maintenance. The taper configuration or vertical height of the coping, which determines the amount of load transferred to each abutment, can be planned to suit each tooth’s condition and designated function in the restoration. In a fixed restoration, the load is always evenly distributed among all the abutment teeth regardless of their condition, because the crowns are permanently cemented to them. In the telescope denture, the amount of force can be individually
JANUARY
1981
VOLUME
45
NUMBER
1
TELESCOPE
RETAINERS
regulated
by modifying
retainers,
according
and
occlusal
the form to their
and leverage
position,
bone
of the support,
conditions.
9.
REFERENCES 1. Langer, A.: Telescope retainers in prosthodontic restorations. Isr J Dent Med 22:107, 1973. 2. Langer, A.: Telescope retainers and their clinical application. J PROSTHET DENT (To be published). 3. Menetrey, J. P., and Nally, J, N.: Etude experimentale comparative sur divers types de crochets et la couronne teltscopique dam les prosthbses des classes I et II de Kennedy. Schweiz Monatschr Zahnheilk 76:571, 1966. 4. Muehlemann, H. R.: Ten years of tooth mobility measurements. .J Periodontol 31:110, 1960. 5. Muehlemann, H. R., Savdir, S., and Rateitschak, K. H.: Tooth mobility: Its causes and significance. J Periodontol 36:148, 1965. 6. Carlsson, G. E., Hedeg&d, B., and Koivumaa, K. K.: II. Studies in partial dental prosthesis. An investigation of mandibular partial dentures with double extension saddles. Acta Odontol Stand 19:215, 1961. 7. Car&son, G. E., Hedeg&d, B., and Koivumaa, K. K.: III. Studies in partial dental prosthesis. A longitudinal study of mandibular partial dentures with double extension saddles. Acta Odontol Stand 20:95, 1962. 8. Carlsson, G. E., Hedeg&d, B., and Koivumaa, K. K.: IV. Studies in partial dental prosthesis. Final results of a 4-year
JOURNAL
announces
10.
11. 12. 13. 14.
15.
16.
longitudinal investigation of dentogingivally supported partial dentures. Acta Odontol Stand 23:443, 1965. Graber, G.: Teleskoprkronen als Fixationsmittel unterer schleimhautgetragener Prothesen. Schweiz Monatschr Zahnheilk 76:611, 1966. Hofmann, M., and Ludwig, P.: Die teleskopierende Totalprothese im stark reducierten Lueckengebiss. Dtsch Zahnaerztl Z 28:2, 1973. Yalisove, I. L.: Crown and sleeve-coping retainers for removable partial protheses. J PROSTHET DENT 16:1069, 1966. Yalisove, I. L., and Dietz, J. B.: Telescopic Prosthetic Therapy. Philadelphia, 1977, George F. Stickley Co. Koerber, E.: Zum Abstuezungsproblem in der zahaerztlichen Prothetik. Dtsch Stomatol lO:l, 1960. Koerber, K. H.: Konuskronen Teleskope Einfuerung in Klinik und Technik. Dr. Alfred Huetig Verlag GmbH Heidelberg, 197 1. Langer, A.: Physiologic and psychologic considerations in oral rehabilitation. Part II. Treatment of functional breakdown of natural dentition. Isr J Dent Med 20:1, 1971. Langer, A.: Long-term preventive aspects in oral rehabilitation of adults and elderly. Part I. Maintenance of balanced functional jaw interaction. J Oral Rehabil 5:129, 1978.
Reprint requeststo: DR. ANSELM LANCER HEBREW UNIVERSITY-HADASSAH
FACULTY OF DENTAI.
MEDICINE
P.O.B. 1172 JERUSALEM, ISRAEL.
new feature-Tips
from our readers
The JOURNAL OF PROSTHETIC DENTISTRY is pleased to announce a new feature. Tips From Our Readers will consist of brief reports describing a successful laboratory or clinical procedure, or timesaving step in a procedure, that authors would like to share with our readers. Tips From Our Readers will be published on a space-available basis throughout the JOURNAL and will appear in a manner similar to the ZADR Prosthodontic Abstracts. Manuscripts must be limited to approximately 250 words, typed double-spaced, with no more than two black and white illustrations. Color illustrations will not be accepted. The format for title, author(s), institution, and city will be the same as that used for full-length articles. References will not be accepted. Footnotes for commercial products will be used, but they should be held to a minimum. The Tips must describe a commercial a helpful procedure or timesaving step, and of course, they must not be used to promote product. Reprints will be available.to authors at the usual cost. Tips From Our Readers will be accepted immediately for evaluation.
THE JOURNAL OF PROSTHETIC
DENTISTRY
43
University-Hadassah
Faculty
of Dental
Medicine,
R
emovable partial prostheses are borne partly by the remaining dentition and partly by the mucoperiosteal tissues. These dentures are usually supported and retained with clasps, precision, or semiprecision attachments. An effective type of retainer, possessing retention, support, and a splinting action between multiple abutment teeth, is a double crown known as the telescope retainer.‘. ’ The primary coping of this retainer unit is cemented to the abutment tooth. The secondary crown, which is made to fit and to be held in position by intersurface tension, is rigidly connected with the removable superstructure. In restorations containing two or more telescope crowns, the superstructure acts as a rigid splint when in position, interlocking the primary and secondary parts to act as a functional unit (Fig. 1). Telescope crowns have proven more effective than other direct retainers.:’ Their degree of retention can be planned to suit different situations by modifying the design. The amount of intersurface friction depends on the configuration of the taper angle and area of surface contact. Telescope crowns can also be used as indirect retainers to prevent dislodgement of the distal extension base away from the edentulous ridge. The resistance to this movement is built-in in rigid telescope retainers with cylindrical or conical primary copings designed with no free space between both components. One of the main advantages of telescope retainers is that, being pericoronal devices, they transmit the occlusal forces in the direction of the long axes of the abutment teeth (Fig. 1). This has proven to be the least damaging application force. Lateral forces exert traumatic pressure on the abutments.‘.”
*Associate Professor
and Head,
Department
+ 07900.70/00
1981 The
of Oral
Rehabilita-
tion.
0022-3913/81/010037
C. V. Moshy
Co.
Jerusalem,
Israel
RIGID AND RESILIENT PARTIAL DENTURES
TELESCOPED
There is a controversy in distal-extension partial dentures, whether to rigidly attach the denture to the abutment teeth or to interpose resilient stress-breaking elements between them, reducing the transfer of traumatic forces from the denture to the teeth. Hence, modifications have been introduced to provide freedom of rotation between the primary and secondary crowns, building the stress-breaking principle into the retainer itself.’ The concept of a resilient removable denture seems to be generally accepted where only a small number of teeth are left for supportY Hofmann and Ludwig,“’ for a period of 2 years, observed 72 patients with dentures built over abutments with telescope crowns. These were adjusted to provide a mucosal resiliency factor of 0.2 to 0.5 mm. In all patients, no more than three abutment teeth were left in the restored arches. Hofmann and Ludwig found that most of the teeth were stable during the first 2 years of use. With time, mobility did increase at a creeping rate, and four teeth had to be extracted during the period. Yalisove’ ’ and Yalisove and Dietz” used crown and sleeve coping telescope retainers with a conical taper configuration, irrespective of the number of abutments. The gingival third of the copings contained a 0.003 to 0.010 inch space between the sleeves and crowns, allowing for rotation of the secondary crowns anchored in their denture. This design eliminated the frictional retention of the denture without impairing the splinting action. When a lateral force was exerted on one side of the arch, the stress was properly redistributed to the rest of the abutments and to the other side. E. Koerber’:’ used the rigid telescope denture when possible, but favored a resilient prosthesis when the small number of remaining teeth and their distribu-
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
37
Fig.
1. Superstructure containing the secondary crowns (SC), is a telescope restoration, acting as a rigid splint to interlock the secondary and primary crowns (PC). The telescope retainer transfers the occlusal forces in the direction of long axes of the abutment teeth (arrows).
Fig. 4. Two canine and three premolar primary copings cemented in place.
Fig. 5. Tissue surface of the removable bilateral dist& Fig, 2. Before treatment. Patient needs a complete maxillary denture and a removable bilateral distal-extension mandibular partial denture.
extension partial denture. Secondary crowns, splinted on one side with pontic (arrow) and soldered together on the other side, are rigidly attached to the distal extensions The rigid sublingual bar connector provides bilateral splinting to the abutments.
Fig. 3. Old dove1 crowns (Richmond) on premolars and canines, prepared for inner copings.
38
Fig. 6. Completed restoration in the mouth.
JANUARY
1981
VOLUME
45
NUMBER
1
TELESCOPE
RETAINERS
Fig. 7. Before treatment. Maxillary remade. A unilateral distal-extension indicated.
crowns must be partial denture is
Fig. 9. Abutment
big.
Fig. 8. Teeth after removal of crowns.
tion justified it. K. H. Koerber’-’ felt that the rigid telescope denture is healthier, prolonging the life of the abutment. When all occlusal factors are considered, this principle seems to have a prophylactic effect on the rest of the dentition. Intense functional stimulation to the periodontal tissues of the abutment teeth causes a reactive adaptation following the resorption of the bone support under the denture-base extension. Indeed, clinical experience suggests that taking advantage of periodontal tooth support and relying less on mucoperiosteal support ensures better function and longer preservation of the dental arch.‘“. I’ The insertion of stress-bearing elements into the retainer construction or their interposition between the abutments and mucosally borne parts of the removable superstructure may reduce the total load transmitted to the abutment teeth and prolong their
THE JOURNAL
OF PROSTHETIC
DENTISTRY
10.
Milled,
teeth built up with post cores.
shoulderiess,
cemented to all maxillary
cone-shapea
copings
are
abutment teeth.
survival. On the other hand, the soft supporting tissues may receive the occlusal forces so that the denture may be depressed following traumatic bone resorption. Therefore, the stability of occlusal harmony cannot be maintained very long as the natural teeth come into premature contacts with their antagonists. When using a rigid-type telescope denture, it is important to secure maximal extension of denture base coverage, similar to that used in complete denture techniques. CLINICAL
APPLICATIONS
The best way to preserve the stability and efficiency of the dental arch, whenever enough tooth support is available, is to use a rigidly constructed removable partial denture. One example is the bilateral distal-extension
39
Fig. 11. Fit of splinted secondary crowns is checked in the mouth.
Fig. 12. Tissue surface of the completed restoration. Secondary crowns are an integral part of the superstructure. Rigid palatal connector ensures the abutments a bilateral group action.
Fig. 13. Completed restoration in place.
40
Fig. 14. In a traffic accident, the patient lost the entiw segment of anterior teeth and three premolars.
Fig. 15. Teeth prepared for inner copings.
(Kennedy I) restoration. Cross-arch splinting is nrc‘essary to lend bilateral support? and stability is secured by soldering together secondary crowns ad.jacent to the edentulous spaces (Figs. :! through 6). Because of advanced periodontal disease. the USC of multiple abutments was indicated after some severely affected mandibular teeth bvere extracted and the remaining teeth were treated periodontallv. All maxillary teeth had to be extracted and an immediate denture made. An alternative solution may also bc considered. composed of two unilateral three-unit fixed partial dentures, extending from the canines to the second premolars, with rigid T-type precision attachments built into the second premolars or using clasps for anchorage. Because of the relatively small contact surfaces between the attachment and receptacle
JANUARY
1981
VOLUME
1s
NUhlBER
I
TELESCOPE
RETAINERS
Fig.
16.
Milled copings on the cast.
Fig. 17. Cast gold superstructure is a one-piece unit containing soldered secondary crowns and a retention frame for the denture base. components of the T-type precision attachments, they tend to wear out in distal-extension partial dentures in time, loosing their stabilizing and crossarch splinting action. Thus, the retentive and supporting advantages of the attachments and cast clasps are questionable in the long run. The large surface contact of parallel walls in the double crowns ensures good direct and indirect retention, cross-arch stabilization, and support of the distal extension of denture bases obtained by a functional closed mouth impression of the mucosal denture support area. One additional advantage of telescope retainers over precision attachments and clasps is their more axial transfer of occlusal load that produces less rotational torque upon abutment teeth. A second example is a unilateral distal extension (Kennedy II) restoration where leverage exerted by
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 18. Tissue surface finished superstructure base coverage.
has broad
Fig. 19. Finished restoration on the cast. the distal extension of the removable denture is significantly reduced by multiple abutment splinting. A good result could have been expected without including all maxillary teeth in the construction. However, since all the teeth needed crown restorations, they were included in the prosthodontic construction (Figs. 7 to 9). In the course of treatment, the conical double crown design was chosen (Fig. lo).’ To ease the insertion of the secondary crowns, the occlusal edges of the primary copings were bevelled at slant angles. For the sake of continuity and rigidity of the anterior removable splint, a pontic was included to replace the missing right lateral incisor. In this solution, the occlusal forces are distributed evenly among all remaining teeth in a favorable direction to their long axes. The close fit between the primary and secondary crowns ensures
41
Fig. 20. Cemented inner copings in the mouth.
Fig. 22. Arrow points to cement exposure caused by wear after 7 years. Telescope unit had to be remade. had to be replaced because of the wear of the gold on the occlusal surface, exposing cement (Fig. 22). Except for this and occasional base relining, the situation remained stable. SUMMARY
Fig. 21. Completed
prosthesis in the mouth.
the entire restoration a high degree of retention, stability, and ,joint group action of the splinted individual abutments (Figs. 11 to 13). A third restoration (Kennedy IV) involves a young patient who lost his mandibular anterior teeth, three premolars, and extensive alveolar bone in a traffic accident (Fig. 14). The shortness of the posterior teeth made any kind of intracoronal precision attachments impossible (Fig. 15). Because of the patient’s age, should cast clasps have been used, the abutment teeth would have had to be covered with crowns for protection against caries. Such clasps would not be esthetic nor would they have good mechanical qualities. Since the teeth needed to be prepared for crowns, telescope retainers were used (Figs. 16 and 17). A functional impression was made with an individual acrylic resin base attached to the gold framework (Fig. 18). A removable denture, based upon six telescope retainers was constructed in the course of treatment (Figs. 19 through 21). During a 12-year follow-up period, two of the telescope units
42
Telescope crowns used in removable partial dentures reduce the destructive horizontal and rotational occlusal forces by directing them more axially and less traumatically than other retainers. These properties are combined with excellent conditions for cross-arch and multiple abutment splinting. If one of the abutment teeth needs extracting, the denture can be repaired with acrylic resin simply by remaking the secondary crown into a pontic. The single copings can be easily cleaned due to the good accessibility around their gingival margins. They also protect the abutment teeth against caries and thermal irritation. Soldering of the primary copings or their connection with accessory bars is not necessary in rigidly constructed telescope crowns, because the secondary crowns incorporated in the superstructure provide sufficient rigidity. In addition, the splinted copings gingival hyperplasia often cause inflammatory because the solder joints are too close to the gingival margins, preventing proper hygiene maintenance. The taper configuration or vertical height of the coping, which determines the amount of load transferred to each abutment, can be planned to suit each tooth’s condition and designated function in the restoration. In a fixed restoration, the load is always evenly distributed among all the abutment teeth regardless of their condition, because the crowns are permanently cemented to them. In the telescope denture, the amount of force can be individually
JANUARY
1981
VOLUME
45
NUMBER
1
TELESCOPE
RETAINERS
regulated
by modifying
retainers,
according
and
occlusal
the form to their
and leverage
position,
bone
of the support,
conditions.
9.
REFERENCES 1. Langer, A.: Telescope retainers in prosthodontic restorations. Isr J Dent Med 22:107, 1973. 2. Langer, A.: Telescope retainers and their clinical application. J PROSTHET DENT (To be published). 3. Menetrey, J. P., and Nally, J, N.: Etude experimentale comparative sur divers types de crochets et la couronne teltscopique dam les prosthbses des classes I et II de Kennedy. Schweiz Monatschr Zahnheilk 76:571, 1966. 4. Muehlemann, H. R.: Ten years of tooth mobility measurements. .J Periodontol 31:110, 1960. 5. Muehlemann, H. R., Savdir, S., and Rateitschak, K. H.: Tooth mobility: Its causes and significance. J Periodontol 36:148, 1965. 6. Carlsson, G. E., Hedeg&d, B., and Koivumaa, K. K.: II. Studies in partial dental prosthesis. An investigation of mandibular partial dentures with double extension saddles. Acta Odontol Stand 19:215, 1961. 7. Car&son, G. E., Hedeg&d, B., and Koivumaa, K. K.: III. Studies in partial dental prosthesis. A longitudinal study of mandibular partial dentures with double extension saddles. Acta Odontol Stand 20:95, 1962. 8. Carlsson, G. E., Hedeg&d, B., and Koivumaa, K. K.: IV. Studies in partial dental prosthesis. Final results of a 4-year
JOURNAL
announces
10.
11. 12. 13. 14.
15.
16.
longitudinal investigation of dentogingivally supported partial dentures. Acta Odontol Stand 23:443, 1965. Graber, G.: Teleskoprkronen als Fixationsmittel unterer schleimhautgetragener Prothesen. Schweiz Monatschr Zahnheilk 76:611, 1966. Hofmann, M., and Ludwig, P.: Die teleskopierende Totalprothese im stark reducierten Lueckengebiss. Dtsch Zahnaerztl Z 28:2, 1973. Yalisove, I. L.: Crown and sleeve-coping retainers for removable partial protheses. J PROSTHET DENT 16:1069, 1966. Yalisove, I. L., and Dietz, J. B.: Telescopic Prosthetic Therapy. Philadelphia, 1977, George F. Stickley Co. Koerber, E.: Zum Abstuezungsproblem in der zahaerztlichen Prothetik. Dtsch Stomatol lO:l, 1960. Koerber, K. H.: Konuskronen Teleskope Einfuerung in Klinik und Technik. Dr. Alfred Huetig Verlag GmbH Heidelberg, 197 1. Langer, A.: Physiologic and psychologic considerations in oral rehabilitation. Part II. Treatment of functional breakdown of natural dentition. Isr J Dent Med 20:1, 1971. Langer, A.: Long-term preventive aspects in oral rehabilitation of adults and elderly. Part I. Maintenance of balanced functional jaw interaction. J Oral Rehabil 5:129, 1978.
Reprint requeststo: DR. ANSELM LANCER HEBREW UNIVERSITY-HADASSAH
FACULTY OF DENTAI.
MEDICINE
P.O.B. 1172 JERUSALEM, ISRAEL.
new feature-Tips
from our readers
The JOURNAL OF PROSTHETIC DENTISTRY is pleased to announce a new feature. Tips From Our Readers will consist of brief reports describing a successful laboratory or clinical procedure, or timesaving step in a procedure, that authors would like to share with our readers. Tips From Our Readers will be published on a space-available basis throughout the JOURNAL and will appear in a manner similar to the ZADR Prosthodontic Abstracts. Manuscripts must be limited to approximately 250 words, typed double-spaced, with no more than two black and white illustrations. Color illustrations will not be accepted. The format for title, author(s), institution, and city will be the same as that used for full-length articles. References will not be accepted. Footnotes for commercial products will be used, but they should be held to a minimum. The Tips must describe a commercial a helpful procedure or timesaving step, and of course, they must not be used to promote product. Reprints will be available.to authors at the usual cost. Tips From Our Readers will be accepted immediately for evaluation.
THE JOURNAL OF PROSTHETIC
DENTISTRY
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