Taira et al.

Int Chin J Dent 2004; 4: 51-55.

Osseointegrated implant connected with natural tooth using asemiprecision attachment: A clinical report
Yohsuke Taira, DDS, PhD, Kiyoshi Nagano, DT, and Mitsuru Atsuta, DDS, PhD
Division of Fixed Prosthodontics and Oral Rehabilitation, Nagasaki University Graduate School of
Biomedical Sciences, Nagasaki, Japan
Present report consists of a clinical evaluation of an implant-tooth supported prostheses using an
intracoronal semiprecision attachment. An osseointegrated implant was inserted in the mandible as analternative to the right second molar. The superstructure was designed as a fixed partial denture to replace
the missing mandibular right first molar, and the attachment was used between the pontic and mandibular
right second premolar. Although slight gingival recession was observed around the implant after 11 yearsof service, no accidental changes were found in the implant body, the natural tooth abutment, or thesuperstructure. The success resulted from certain clinical guidelines including plaque control after thecompletion of prosthodontic treatment. The semiprecision attachment made maintenance easy andadequately connected the implant with the natural tooth for long term. (Int Chin J Dent 2004; 4: 51-55.)
Key Words: biomaterial, implant-tooth support, prognosis, superstructure.

Introduction
Cylindrical root-form osseointegrated implants form a popular option for replacing missing teeth.
Although a variety of cylinders are applicable, whether or not the implant can be connected with the natural
tooth is of great concern to clinicians in the selection of a suitable implant system.1,2 The IMZ system(Friadent GmbH, Mannheim, Germany) was reported to be characterized by an intramobile element (IME)and an intramobile connector.3-5 These intramobile components, which are made with polyoxymethylene,
simulate the physiological movement of a natural tooth.6 The distributed occlusal stress is considered tofacilitate bone remodeling around the implant. The intramobile components must be renewed periodically,
due to deterioration and surface contamination.7
Screw-fixed attachments have been used as a standard of care for IMZ system with good results.8
Semiprecision attachments, such as custom fabricated keyway and prefabricated slide type attachments,
allow the superstructure to be removed when exchanging the intramobile components.9 In comparison to
the screw-fixed attachments, however, limited information is available concerning implant-tooth supported
prostheses fabricated using semiprecision attachments.

This clinical report followed a prosthodontic

service with the purpose of evaluating an intracoronal semiprecision attachment placed between the IMZ
implant and the natural tooth abutment.

Clinical Report
A 33-year-old healthy female had a chief complaint of mobility of the fixed partial denture placedbetween the mandibular right second premolar and second molar. The patient was unhappy with the fixed
partial denture and wanted a fundamental solution.

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Fig. 1. Intraoral view before treatment with the dental implant.
Fig. 2. a, Occlusal view following placement of IMZ implant and the superstructure.
The superstructure was partially veneered with fired porcelain.
b, The distal part of the superstructure could be detached from the second premolar
abutment of the semiprecision attachment.
Fig. 3. Intramobile element (IME) and transmucosal implant extension, which were replaced at
6 months intervals. Considerable dental plaque was attached to the screw of IME.
Fig. 4. Lateral views and radiographs of the implant-tooth supported prosthesis. Except for slightgingival recession, no significant changes were observed between 4 months and 11 years
after the completion of the superstructure.
a, Clinical situation showing the prosthesis 4 months after treatment.
b, Radiograph, corresponding to Fig. 4a.
c, Clinical situation showing the prosthesis 11 years after treatment.
d, Radiograph, corresponding to Fig. 4c.
A patient interview was conducted, records were reviewed, and radiographs were made; diagnosis and atreatment plan were then completed. Severe tooth collapse due to caries was observed around the inserted
post core in the mandibular right second molar. The mobility was therefore resulted from the prostheticloosing. It was explained to the patient that tooth extraction would be advisable, and that prosthetic
treatment was possible by means of a removable partial denture or dental implant. The radiographic
examination suggested that the available bone volume was too small to insert implant in the area of rightsecond molar because of the location of mandibular foramen.
The fixed partial denture was cut in the distal area of the mandibular right second premolar and partiallyremoved, after which the mandibular right second molar was extracted and an interim denture wasfabricated. Eight months after the extraction (Fig. 1), an IMZ system implant body (4 mm in diameter and13 mm long) was inserted in the area corresponding to the distal portion of the mandibular right first molar.
The superstructure was designed as a fixed partial denture in which an attachment (The Beyeler Slide
Attachment, Inoue Attachment Co. Ltd, Tokyo, Japan) was used between the first molar pontic and thesecond premolar restoration (Figs. 2a and 2b). A high gold containing alloy (Degudent Universal, Dentsply
Sankin Co. Ltd, Tokyo, Japan) was cast directly onto the prefabricated attachment to form the male andfemale components of the superstructure, then the metal framework was partially veneered with afeldspathic porcelain (VMK 68, Vita Zahnfabrik GmbH, Bad Säckingen, Germany).
Following placement of the superstructure, observation was conducted on the second week, the firstmonth, the third month, and at intervals of 6 months thereafter. Since the semiprecision attachment used inthis repot did not have minute screws (thus differing from screw type fixation), handling was comparatively
easy.
Dental plaque was attached to IME and transmucosal implant extension (TIE) when they were replaced
at 6 months intervals (Fig. 3). Eleven years after the placement of the superstructure, no significant
changes were found in the implant or the abutment tooth, except for slight gingival recession around theimplant (Figs. 4a-4d). According to the success criteria reported by Esposito et al.,7 it is considered that
this implant-tooth supported prosthesis had functioned well.

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Discussion
Amongst the variety of options available for replacement of missing teeth, this article presented amodification of a traditional technique for implant-tooth supported prostheses.

In situation that

osseointegrated implants are connected to natural teeth, there is concern with respect to potential fracture of
implant components or the natural teeth, bone resorption, secondary caries, and lost screws.7-9 Furthermore,
the natural teeth occasionally subside, causing positional discrepancy in slide type attachments, which may
be due to the differences between the amount of displacement of the implants and that of natural teeth
during loading.2 Although dental plaque attached to the IME (Fig. 3) suggests that the IME was loose, suchaccidents did not occur in this case. The authors speculate that this was because the load applied to theretainer during occlusion was appropriate, the displacement amount of the IME was similar to that of thenatural teeth, the IME and TIE were replaced at comparatively short intervals of 6 months, and the friction
force in the attachment area was sufficiently high.
The IMZ implant system has the potential to survive for over 16 years in the oral environment.5
However, when part of the plasma-sprayed area of the implant body is exposed in the oral cavity
accompanied by gingival recession, plaque control becomes difficult. Regular oral hygiene instruction,observation of occlusal changes and adjustment, and attention to gingival recession are therefore essential
to longer-term success.
The present report suggests that a favorable prognosis may be expected when a three unit fixed partial
denture is planned. Taking the undesirable effects of a cantilever into account, vertical displacement at theattachment may be increased when a load is applied to a multi-unit pontic.
In the limited experience presented here, the intracoronal semiprecision attachment made maintenanceeasier, and proved adequate in the role of connecting the implant with the natural tooth for 11 years.

References
1. Gunne J, Åstrand P, Lindh T, Borg K, Olsson M. Tooth-implant and implant supported fixed partial dentures: a 10-year
report. Int J Prosthodont 1999; 12: 216-21.
2. Watanabe H, Matsushima H, Fujino S, Hoshino K. Regarding as a case connecting osseointegration typeimplant-natural dentition. J Jpn Soc Oral Implant 2000; 13: 146-54.
3. Kirsch A. Plasma-sprayed titanium-I.M.Z. implant. J Oral Implantol 1986; 12: 494-7.
4. Kirsch A., Ackermann KL. The IMZ osteointegrated implant system. Dent Clin North Am 1989; 33: 733-91.
5. Noack N, Willer J, Hoffmann J. Long-term results after placement of dental implants: longitudinal study of 1,964
implants over 16 years. Int J Oral Maxillofac Implants 1999; 14: 748-55.
6. Haganman CR, Holmes DC, Aquilino SA, Diaz-Arnold AM, Stanford CM. Deflection and stress distribution in threedifferent IMZ abutment designs. J Prosthodont 1997; 6: 110-21.
7. Esposito M, Hirsch JM, Lekholm U, Thomsen P. Biological factors contributing to failures of osseointegrated oralimplants. (I) Success criteria and epidemiology. Eur J Oral Sci 1998; 106: 527-51.
8. Fugazzotto PA, Kirsch A, Ackermann KL, Neuendorff G. Implant/tooth-connected restorations utilizing screw-fixedattachments: a survey of 3,096 sites in function for 3 to 14 years. Int J Oral Maxillofac Implants 1999; 14: 819-23.
9. McGlumphy EA. Implant-supported fixed prostheses. In: Rosenstiel SF, Land MF, Fujimoto J (eds). Contemporary
fixed prosthodontics. St. Louis: Mosby; 1995. p. 268-300.

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Reprint request to:
Dr. Yohsuke Taira
Division of Fixed Prosthodontics and Oral Rehabilitation
Nagasaki University Graduate School of Biomedical Sciences
1-7-1, Sakamoto, Nagasaki 852-8588, Japan
Fax: +81-95-849-7689 E-mail: yohsuke@net.nagasaki-u.ac.jp
Received May 8, 2004. Revised May 26, 2004. Accepted May 27, 2004.
Copyright ©2004 by the Editorial Council of the International Chinese Journal of Dentistry.

International Chinese Journal of Dentistry 2004 Outstanding Article AwardInternational Chinese Journal of Dentistry announces the third Outstanding Article Award.
Award:A cash prize of US$ 600 and a certificate of commendation are awarded for the most outstanding article
published in the International Chinese Journal of Dentistry.
Criteria:
Original articles, clinical reports, and dental technology articles published in the Journal between issue 1
and issue 4 are considered for the award. The winning article will be selected by a committee on the basisof scientific impact on the dental professional communities, and interest to the readers. The 2004 Award issponsored by the International Chinese Journal of Dentistry and the following award sponsors.
Award Sponsors:
GC Corporation, Tokyo, Japan, http://www.gcdental.co.jp
Kuraray Medical Inc., Tokyo, Japan, http://www.kuraray.co.jp/dental
Shofu Inc., Kyoto, Japan, http://www.shofu.co.jp
Sun Medical Co., Ltd., Moriyama, Japan, http://www.sunmedical.co.jp
Toho Dental Products, Saitama, Japan
Tokuyama Dental Corp., Tokyo, Japan, http://www.tokuyama-dental.co.jp
3M Health Care Limited, Sagamihara, Japan, http://www.3m.com/espe/
2003 Award Winner:
Nikaido T, Yoda A, Foxton RM, Tagami J.
A resin coating technique to achieve minimal intervention in indirect resin composites: A clinical report
Int Chin J Dent 2003; 3(3): 62-68.

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