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Journal of Oral Science, Vol. 40, No. 1, 43-47, 1998

Case Report

A case report of removable partial denture using the dimple-

bar telescopic system

Morio Iijima Noriyuki Narita, Toshihiko Matsurnoto and Sunao Ikeda

Department of Removable Partial Denture Prosthodontics, Nihon University School of Dentistry at Matsudo, Chiba 271-8587,

University Research Center, Nihon University, Tokyo 102-0074

Received 16 July 1997 and accepted 22 January 1998)

Abstract: The authors have devised a new

attachment for a removable partial denture with a

dimple-bar clasp, guiding channels, and a shoulder,

named the dimple-bar telescopic system. This system

has advantages over the clasp-type retention device in

that it not only satisfies esthetic requirements, but also

improves the handling and adjustability of the

attachment denture. Furthermore, it was shown

clinically that the dimple-bar telescopic system was

free from food impaction when used as an

intracoronal attachment, and maintained a feeling of

comfort during tongue movement and speech. We

present a typical case in which the dimple-bar

telescopic system was used. J. Oral Sci. 40, 43-47,

1998)

Key words: removable partial denture; esthetic

prostheses; telescopic system; attachment.

Introduction

Retention devices for removable partial dentures can

be classified into two types: the general clasp type, and an

attachment system combining male and female portions.

Both are required to be not only functional and easy to

clean, but also esthetically acceptable. The clasp type is

commonly applied to removable partial dentures because

of its simple structure. However, many problems exist

from the viewpoint of esthetics, one of which is exposure

of the metallic color, and in addition, due to crown

contours the clasp type tends to be difficult to keep clean.

In contrast, from both esthetic and hygienic viewpoints,

the attachment system is applicable to many cases of

tooth loss, even if located anteriorly to the dental arch.

The authors have treated 6 patients who required

removable partial prostheses using a new system called

the dimple-bar telescopic system DBT). All the patients

have retained clinically good conditions for more than

five years.

We report a typical case in which the DBT system was

used as a retention device. The system comprises a

dimple-bar clasp 1), guiding channels 2) and a shoulder

2), is capable of withstanding functional pressure, and is

applicable in situations demanding high esthetic quality.

Case Report

The patient was a 45-year-old woman. Tooth loss

comprised the upper right second premolar, upper left

lateral incisor, lower right first and second molars and

lower left second molar. In the mandible, tooth loss was

divisible into class I according to the Kennedy

classification. The patient complained of the following:

1) discomfort due to incompatibility of the crown

prostheses, 2) secondary caries of the upper teeth, and 3)

incompatibility of the one-sided Conus denture mounted

across the lower right edentulous space. She required

improvement of esthetic quality and desired a fixed

prosthesis in the maxilla and removable partial denture in

the mandible. The occlusal plane was not smooth and

early centric occlusal interference was evident. However

she had no notable clinical history, such as evidence of

temporomandibular disorders.

a) channel

b) shoulder

c) dimple

Correspondence to Dr. Morio Iijima, Department of Removable Partial

Denture Prosthodontics, Nihon University School of Dentistry at

Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo-shi, Chiba 271-8587,

Japan

Fig. 1 Inner cap component of the dimple-bar telescopic

system. Inner cap component comprises channel a),

shoulder b), and dimple c).


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Fig. 2a Occlusal view.

Fig. 2b View from defective side.

Fig. 2c Lingual view.

Fig. 3a Views of outer caps and metal frame.

Fig. 3b Views of outer caps and metal frame.

Fig. 3c Porcelain fused to metal crowns and metal frame

assembled on the master model.

Figs. 2 Photographs of inner caps mounted on the master

model.

Fig. 3d DBT system with 2 rigidly anchored free end saddles;

inner and outer caps separated.


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Porcelain fused-to-metal crowns and bridges were

designed as shown in Fig. 4a, b. In the mandible, the DBT

system was applied to the right second premolar and left

first molar using porcelain fused-to-metal crowns, and

prostheses consisting only of a guiding channel. A

shoulder was designed for treatment of the right first

premolar and left second premolar. For treatment of the

tooth loss in the mandible, a metal plate denture was

designed by combining the DBT system, a metal frame,

and an outer cap. On the basis of the cross-arch

stabilization theory 3), a denture was designed

bilaterally, and the altered casting technique was applied

to achieve functional support. Establishment of the

functional support not only protected the abutment tooth,

but also provided a retention effect with a rigid

connecting system.

Fig. 4a

Fig. 4b

Fig. 4c

Fig. 4d

Fig. 4e

Figs. 4a-e Clinical photographs of entire DBT system used in the present case in Figs. 2a-c and 3a-d.

Figs. 4a, b, c, d and e : reflected in a mirror)


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The basic aim of the treatment was to improve esthetic

quality, to correct the occlusal plane, and to make the

movement of the mandible smoother using the mutually

protected occlusion for the anterior guidance of

mandibular movement.

The basic structure of the DBT system is shown in

Figs. 1, 2a-c and 3a-d. The inner cap prosthesis of the

abutment tooth consists of a guiding channel formed

along the distal and mesial axial walls of the abutment

tooth, a shoulder formed on the lingual axial wall, and a

dimple formed on the surface adjacent to the missing

tooth. The outer cap is designed to accept the components

of the inner cap, and the dimple faces a semi-spherical

protrusion designed on the tip of the resilient retention

arm of the dimple-bar.

The friction force generated between the main and

auxiliary structural components, which include a rigid

inner cap and a removable outer cap, enable superb

retention. The auxiliary component consists of a dimple

and dimple-bar.

The guiding channel restricts the direction of the

denture pathway and protects the outer cap from

excessive external force and abrasion during wear and

removal. The guiding channel also produces a clamping

effect that increases the stability of the outer cap to

prevent it from moving to the lateral direction.

The shoulder has a rectangular shape designed to

support the vertical occlusal force, and the width of the

shoulder is adaptable according to the shape of the crown

and the direction of the dental axis. If the width of the

lingual axial wall is insufficient to support functional

force, it can be supported at the bottom of the guiding

channel.

The dimple on the axial wall at the side of the missing

tooth provides the force to retain the outer cap by

insertion of the semi-spherical protrusion on the tip of the

dimple-bar. The dimple is a semi-spherical retraction.

The depth of the dimple is equal to half that of the 5 or

6 round bar. The diameter of the dimple is the same as

that of the 5 or 6 round bar. The length of the dimple-

bar is 1.5 cm (4). Therefore, the force from the dimple-

bar supplements the friction force between the inner and

outer caps, and because it is on the axial wall to the side

of the missing tooth, the dimple-bar is covered by the

mesial surface of the artificial teeth.

Discussion

The retaining appliance for the removable partial

denture was developed in consideration of the increasing

demand for esthetic quality. Many attachments have been

designed, but most have been used without improvements.

Owing to progress in casting techniques and the

development of the parallelometer, the compatibility and

operating properties of the telescopic crown have

improved markedly. For example, the Channel Shoulder

Pin (CSP) introduced by Steiger (2), the Telescopic

system devised by Botteger (5), the removable closure of

the interdental space by Gaerny (6), and the cone

telescope developed by Korber (7) have been widely used

in a clinical setting. However, these are very expensive,

custom-made semi-precision crowns. The ability of

dentists to handle such developments must be improved,

as the soldering and manufacturing processes are

complex, and some difficulties exist in postoperative

maintenance due to reduction of retaining ability and

breakage. Recent progress in reproduction techniques for

models in the process of manufacture of metal frames has

made it possible to make more complex casts, resulting in

improvements in compatibility and retaining ability.

The retaining ability of a telescopic crown decreases in

accordance with wearing time. If 1000 denture-wearing

times are repeated, the retaining force of the telescopic

crown decreases to 50% of its original force (8).

Therefore, an auxiliary retaining appliance is required to

compensate for this decrease in retaining force. In this

case, the dimple-bar designed for the lower left first

molar and lower right second premolar produces a

retaining force through insertion of the semi-spherical

protrusion part into the dimple, and maintains the

retaining force for extended periods due to its high

flexibility. In addition, it is possible to control the

retaining force by simply adjusting the dimple-bar.

Regarding the submergence of the denture base in

accordance with rotation of the denture around the

abutment teeth during functional loading, the ridge of the

alveolar bone beneath the denture base might be absorbed

and reduced. Therefore, in the present case a newly

altered casting technique was applied to obtain an optimal

functional supporting effect with the denture base.

Furthermore, in addition to the altered casting technique,

guiding channels were formed at right angles to the

occlusal plane on the left second premolar and the right

first premolar. It is conceivable that guiding channels at

right angles to the occlusal plane might be effective for

preventing submergence of the partial denture. Also,

taking the vertical support of the abutment tooth at

occlusal loading into account, shoulders were formed at

right angles to the direction of occlusal loading on the

lingual wall from the mesial to the distal guiding

channels. From the above, it can be assumed that the

DBT system has a clamping effect which stabilizes and

minimizes functional loading on the remaining tissue; i.e.

the abutment tooth and its surrounding tissue, and

beneath the denture base. Also, as the DBT system can

be formed within the intracoronal space of the abutment

tooth, it has an advantage in maintaining the comfort of

the tongue during orofacial motor functions, such as in

chewing and speech.

Conclusion

Our clinical evaluation of the DBT system can be

summarized as follows :

1. The system satisfied the esthetic desire of the patient

by showing no exposed metallic surfaces of the

retaining appliance.

2. It is possible to compensate for the decrease in

retaining force of the telescopic system using the

dimple-bar.

3. A porcelain fused-to-metal crown was applicable to

the DBT system.


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4. Improvement of handling properties and adjustability

resulted in easy clinical application.

5. The intracoronal attachment with the DBT system is

easy to clean, and the patient is satisfied with the

result.

Through this therapeutic experience, it is considered

that this system is favorable for clinical cases in which

esthetic quality is demanded.

References

1. Matsumoto, T. 1985) Aesthetic prosthesis utilizing

Dowel, Dimple-bar System. Nihon Univ. J. Oral Sci.

11, 35-41 in Japanese)

2. Steiger, A.A. 1949) Planostat und Parallelofor zur

Rillen-Schulter-Stift-Befestigung von partiellen

Prothesen. Schweiz. Mschr.

Zahnheilk. 59, 21-29 in German)

3. Fauchard, P. 1969) The surgeon dentist or treatise on

the teeth. 2nd ed., Vol.11, Milford House Inc., New

York, 88-92

4. Kuroda, N., Ishii, T., Iijima, M., Shimazaki, R.,

Matsumoto, T. and Ikeda, S. 1988) Utilizing of

tubing method to horizontal bar clasping system.

Nihon Univ. J. Oral Sci. 14, 469-472 in Japanese)

5. Mager, H. 1973) Das Teleskopsystem in der

zahnarztlichen Prothetik. 4th ed., Johann Ambrosius

Barth, Leipzig, 33-85 in German)

6. Gaerny, A.A. 1972) Removable closure of the

interdental space C.I.S.). Buch-und Zeitschriften-

Verlag Die Quintessenz, Berlin, 13-34

7. KOrber, K. 1983) Konuskronen. Das rationelle

Teleskopsystem Einfiihrung in klinik und Technik.

5th revised ed., Dr. Alfred Huthig Verlag, Heidelberg,

64-90 in German)

8. Nagasawa, T., Kubo, M., Maeno, N., Yamashina, T.

and Tsuru, H. 1978) Experimental study on the

decrease of retentive force of several attachments. J.

Hirosima Univ. Dent. Soc. 10, 63-69 in Japanese)

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