Tanoue et al.

Int Chin J Dent 2005; 5: 97-100.

Repair and re-seating of resin-bonded fixed partial denture
performed after minimal abutment reduction: A clinical report
Naomi Tanoue, DDS, PhD,a Saiji Shimoe, BA, CDT,b Mika Nemoto, DDS, PhD,c andHideo Matsumura, DDS, PhDc
aDepartment of Specialized Dentistry, Nagasaki University Hospital of Medicine and Dentistry,bNagasaki, Division of Oral Health Science, Hiroshima University Faculty of Dentistry, Hiroshima, andcDepartment of Crown and Bridge Prosthodontics, Nihon University School of Dentistry, Tokyo, JapanThis clinical report describes repairing and re-seating of a resin-bonded fixed partial denture placed in a patient
suffering from periodontitis as well as leukemia. A mandibular seven-unit fixed partial denture (FPD) made of typeIV gold alloy was seated in a 62-year-old male patient with an adhesive resin. Five years and two months after
seating, two retainers detached probably due to labial inclination of the abutments. Two retainers were cut with adiamond rotary instrument, and the fractured composite veneer was repaired extraorally. The abutments wereminimally reduced to remove the adhesive resin remnant. The repaired five-unit cantilever FPD was re-seated witha combination of the Metaltite primer and the Super-Bond Opaque resin. The FPD and abutments have beenfunctioning satisfactorily for more than six months. (Int Chin J Dent 2005; 5: 97-100.)
Key Words: adhesive, indirect composite, primer, repair, resin-bonded fixed partial denture.

Introduction
Resin-bonded fixed partial dentures (FPDs) and splinting devices are seated generally to abutments with
sufficient enamel structure. Clinicians frequently encounter cases indicated for FPD or splint especially in themandibular anterior dentition. It is desirable for patients to keep the reduction of tooth structure to a minimallevel during preparation of vital abutment teeth. Several types of noble metal adhesive systems have beendeveloped during the last decades,1-8 and resin-bonded castings made of noble metal alloys are widely employed
as alternatives to base metal alloy castings.9-16
Prostheses made of noble metal alloys have several advantages over those made of base metal alloys, i.e.,
improved adaptation to abutments, adequate mechanical properties after age-hardening, adjustability ofmaxillo-mandibular occlusal contact, and polishability. Limited information, however, is available regarding
bonding systems, clinical outcome, and techniques to repair or re-seat of such FPDs and splints. This clinicalreport describes the procedure of repairing and re-seating of a fractured and once detached resin-bonded FPD in
conjunction with minimal intervention to abutment tooth structures.

Clinical Report
Fabrication and seating of the original FPD
A 62-year-old male patient presented with the chief complaint of masticatory disturbance derived frommobility of mandibular anterior and posterior teeth. The patient suffered from periodontitis and leukemia. After
extraction of mobile teeth and initial preparation of periodontal tissue under hemostatic control, the patient
preferred prosthodontic treatment with a resin-bonded FPD.

Figs. 1 and 2 show the post-extraction andpre-operative view of the mandibular anterior dentition. There was a remarkable increase in crown/root ratio
associated with gingival recession. Application of a conventional FPD with full-coverage casting and dental
implants appeared to be difficult in this case. Fortunately, the mobility of abutments was within the range ofgrade I.

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Figs. 1 and 2. Pre-operative lateral and frontal views.

Fig. 3.

Metal framework of the FPD.

Fig. 4.

Occlusal view of the FPD.

Fig. 7.

Fracture of the pontic veneer. Figs. 8 and 9. Adhesive-cohesive failure of the Super-Bond resin.

Fig. 10. Dislodged FPD.

Figs. 5 and 6. Seven-unit FPD seated with Metaltite and Super-Bond.

Figs. 11 and 12. Frontal and occlusal views of the re-seated FPD.

The mandibular central incisors, right canine, and first premolar were missing. The left canine, lateral incisors,
and right second premolar were selected as abutment teeth. Tooth reduction was limited to within enamel asmuch as possible. An impression was made with silicone elastomeric materials (Exafine Putty and Injection, GC
Corp., Tokyo, Japan) using a stock tray. A working cast was prepared with die and lab stones, and mounted on
an articulator with an opposing cast. The wax pattern of the FPD was fabricated, invested with a cristobalite
material, and a metal framework consisting of four retainers and three pontics was cast from type IV gold alloy(Casting Gold type IV M.C., GC Corp.; Fig. 3). The facial surface of the pontics was veneered with adual-polymerized indirect composite system (Alloy Primer, Cesead II Opaque Primer, Cesead II Opaquecomposite, and Estenia composite, Kuraray Medical Inc., Tokyo, Japan). The veneering technique used in thiscase has been reported previously (Fig. 4).1798

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The FPD was tried-in, and the inner surface of the retainers was air-abraded with alumina (Hi-Aluminas,Shofu Inc., Kyoto, Japan) using an air-borne particle abrader (Micro Blaster MB102, Comco Inc., Burbank, CA,USA), and conditioned with a single liquid primer (Metaltite, Tokuyama Dental Corp., Tokyo, Japan). The
abutment enamel surface was etched with 40% phosphoric acid (K-Etchant, Kuraray Medical Inc.), washed withwater, and air-dried.

The FPD was then seated with a tri-n-butylborane (TBB) initiated adhesive resin(Super-Bond C&B Opaque Ivory, Sun Medical Co., Ltd., Moriyama, Japan) using a brush-dip technique (Figs. 5and 6). The patient entered a maintenance program and the FPD was examined regularly.
Repair and re-seating of the FPD
Five years and two months after seating the FPD, the patient felt mobility of the anterior teeth (Fig. 7).
Examination revealed crevices between the two left retainers and abutments. Detachment appeared to be causedby movement of abutments in a mesio-labial direction. The veneered composite was also fractured at the edgeof the incisor pontic.
The FPD was dislodged with a crown remover combined with an ultrasonic instrument. Examination revealed
no recurrent dental caries in all abutments. However, deposition of calculus was apparent at the root surfaces
and periodontitis of the abutments appeared to be taking a turn for the worse. Figs. 8 and 9 show combinedcohesive-adhesive failure of the adhesive resin between the premolar abutment and the retainer, whereas
majority of the adhesive resin remained on the abutment surface rather than on the retainer (Fig. 10).
Two left retainers were cut with a rotary diamond instrument because they could not be seated in their original
position due to inclination of the abutments. The fractured veneer was repaired extraorally with a hybrid
composite (Epricord, Kuraray Medical Inc.), and the modified five-unit FPD was seated again with thecombination of the Metaltite primer and the Super-Bond Opaque resin (Figs. 11 and 12). The resin material
remaining on the abutment surface was removed before bonding the FPD, and reduction of enamel structure
could be restricted to a minimal level. Six months after re-seating, the FPD is still functioning satisfactorily.

Discussion
One of the advantages of resin-bonded FPDs is minimal reduction of abutment teeth. During preparation ofabutments, anesthesia is usually unnecessary. However, the technique of bonding the retainer to minimallyreduced enamel structure has several disadvantages compared with the full-coverage restorative technique. Oneof these is higher probability of detachment of the retainer from the abutment surface. This detachment is moreprobable in a high-mobility dentition.

Abutments affected by periodontitis are frequently located at themandibular anterior area. On the other hand, risk of dental caries is somewhat low in this area. Althoughresin-based adhesives are considerably resistant against tensile stress, the resistance to bending, shearing, andpeeling forces is not particularly high. Resin-bonded FPDs and splints applied to the anterior areas, therefore,tend to detach due to occlusion or inclination of the abutments. Clinicians should be aware of the limitation inlongevity of resin-bonded FPDs especially when attached to mobile abutments.
Movement of abutments in the current case was remarkable compared with other patients. Dental caries,fortunately, was not detected at the abutment surfaces. In addition, the incisor pontic was considerably narrow.
Two left retainers of the FPD were therefore cut, and the FPD was re-seated after repair of the fractured veneer
as a cantilevered FPD. If necessary, the remaining abutments can be fixed using the Super-Bond adhesive withor without using proximal pin retainers.

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Even after detachment of the original FPD, the outline form of the left abutments remained intact. This is themost outstanding advantage in application of resin-bonded FPDs. Continuous efforts to improve bond durabilityof such techniques are mostly required.

Also, careful selection of indication and adhesive technique areimportant factors for the success of the resin-bonded FPDs.
Acknowledgment
This clinical report associated with survival analysis of resin-bonded FPDs and bonding of noble metal alloy was
supported in part by a Grant-in-Aid for Scientific Research C 17592030 (2005-2007) from the Japan Society for thePromotion of Science (JSPS), and by Uemura Fund (2005), Nihon University School of Dentistry.

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Reprint request to:
Dr. Naomi Tanoue
Esthetic Dentistry, Department of Specialized Dentistry
Nagasaki University Hospital of Medicine and Dentistry
1-7-1, Sakamoto, Nagasaki 852-8588, Japan
Fax: +81-95-849-7689 E-mail: t-naomi@net.nagasaki-u.ac.jp
Received November 8, 2005. Revised November 30, 2005. Accepted December 7, 2005.
Copyright ©2005 by the Editorial Council of the International Chinese Journal of Dentistry.

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