Prosthodoritics

The all-porcelain, resin-bonded bridgeMatthias Kern* / Helmut Knode** / Jörg Rudolf Strub***

This case report describes the clinical and laboratory procedures for the fabrication andinsertion of In-Ceram alt-porcelain, resin-bonded bridges. Alt-porcelain crowns andfixed partial dentures have better biocompatibitity and better esthetic results than doceramometal restorations. In-Cerani has been shown to have better physical propertiesthan other ceramic or glass materials. However, long-term clinical studies of the mate-rial are not yet available. (Quintessence Int 1991:22:257-262.)

Introduction

The primary and the secondary (after rebonding}long-term success rates of resin-bonded bridges withmetal frameworks were between 66,5% and 88.0%and 93.0% and 93,5%, respectively,'"' The esthetic dis-advantage of conventional resin-bonded prostheses isthe grayish shine-through of the metal framework,'' Inaddition, the biocompatibihty of certain nonpreciousmetal alloys is in question,'-^

To overcome these problems, all-porcelain, resin-bonded bridges were introduced,'"* The greatest dis-advantage of using traditional ceramic materials incrown and bridge prosthodontics is their lack of sta-bility in the oral environment,' The development ofIn-Ceram (Vita Zahnfabrik), a new ceramic materialthat has shown better stabihty than have traditionalceramics,'""'- makes the longevity of all-porcelain, res-in-bonded prostheses appear more promising.

This paper describes a new technique for the fab-rication of the In-Ceram resin-bonded bridge and theclinical procedures for its insertion.

Assistant Professor, Department of Prosthodontics, Aibert-Ludwigs University, School of Dentistry, Hugstetterslrasse 55,7800 Krciburg, Germany,Undergraduate Student, Albert-Ludwigs University, School ofDentistry,Professor and Chairman, Department of Prosthodontics,Albert-Ludwigs University,

Case report

The patient was missing toodi 11, Tooth 12 was cariesfree, and tooth 21 was restored mesially with com-posite resin material (Figs 1 and 2).

The resorbed marginal ridge in the area of tooth 11was built up pre pro s ihe tic a lly with a piece of pre-shaped lyophilized cartilage to create an ideal soft tis-sue profile for the planned ridge lap pontie. The sur-gical ridge augmentation procedure is important forgetting optimal esthetic and functional results (Fig 3),A removable provisional denture was inserted in themaxillary arch (Figs 4 and 5) for 8 months to allowthe augmented ridge to heal and remodel (Figs 6and 7),

At that time, a minimal veneer preparation was cre-ated on the lingual side of the abutment leeth, 12 and21, If there is no occlusal contact between the all-porcelain, resin-bonded fixed partial denture and theopposing teeth, only 30 to 50 fim of superficial enamelis removed. The removal of the outer layer of enamel,which has a high fluoride content, provides the bestbonding strength between the resin and the toothstructure after etching," In the occlusal contact area,the depth of the tooth preparation should be 0,5 mmto provide space for a sufficient thickness of porcelain,

Hydrocolloid impressions were then taken and mas-ter casts were poured in Type IV die stone. One of themaster casts and the study cast of the mandible weremounted in the articulator by use of the facebow, Awaxup of the planned In-Ceram coping was made tocheck that no occlusal and functionai discrepancieswere present (Fig 8),

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Fig 1 Frontal view of the preoperative situation. Tooth 11is missing and the alveolar ridge in the area ol tooth 11 isresorbed.

Fig 2 Occlusal view of the preoperative situation.

Fig 3 Ridge augmentation with lyophilized cartilage in thearea of tooth 11 {Courtesy of Dr M. Hurzeler, Albert-LudwigsUniversity).

Fig 4 Frontal view ot the removable provisional pros-thesis.

Fig 5 Occlusal view of the removable provisional prosthesis.

Fig 6 Frontal view 8 months after the alveoiar ridge aug-mentation in the area of tooth 11,

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iF' Ifj

Fig 7 Occlusal view 8 months after alveolar ridge aug-mentation in the area of tooth 11.

Fig 8 Occlusal view ot the waxup of the coping on themaster cast, which is made out of Type IV die stone.

Fig 9 Palatal view of the transferred waxup onto Ihe spe-cial piaster cast.

Fig 10 (right) Injection of the In-Ceram coping materialthrough the injection sprue Into the duplicated mold of thewaxup with the special plaster cast.

Then, a duplicated cast of the abutment teeth. 12and 21, and the pontic area was made out ofa specialplaster provided with the In-Ceram kit. The waxup ofthe coping was then transferred onto the special plas-ter cast (Fig 9). A duplication mold to the waxup andthe special plaster cast was made. Then the waxup wasremoved from the special plaster cast. It was replacedhy an aluminum oxide slip, which was pressed throughthe injection spine into the duplication mold (Fig ]0).The moistness of the slip cast was absorbed by thespecial plaster cast. Afterward, the slip cast was taken

out of the duplication mold together with the specialplaster cast. The special plaster cast was glued on analuminum oxide firing tray with cyanoacrylate resin.Then, it was cut with a saw mesial to teeth 12 and 21(Fig 11), According to the manufacturer, the In-Ceramcoping can also be produced directly on the specialplaster cast with a brush build-up technique.

After the application of the In-Ceram stabilizer, theslip cast and the special plaster cast were sintered inthe Vita Inceramat furnace {Vita Zahnfabrik) at1120 °C for 2 hours. Contrary to the slip cast, the

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Fig 11 In-Ceram coping after removal Irom the duplicationmold and after the special plaster cast has been glued ontoan aluminum oxide tiring Iray and cut with a saw.

Fig 12 in-Ceram coping after ttie sintering process. Notethe shrinkage ot the special plaster cast. The sintered cop-ing has remained slable.

Fig 13 In-Ceram coping after glass infiitration finng. Ex-cess glass is removed by air abrasion with aluminum oxideparticles.

Fig 14 Frontal view of the veneered in-Ceram resin-bond-ed bridge.

Fig 15 Palatai view of the veneered In-Ceram resin-bond-ed bridge.

Fig 16 Occlusal view ot the maxillary teeth covered witha rubber dam ready lor cementation.

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Fig 17 Frorital u¡ew ot the inserted all-porcelain, resin-bonded bridge.

Fig 18 Ocelusal view ot the all-porcelain, resin-öondedbridge.

special plaster cast exbibits shrinkage during the sin-tering process (Fig 12). However, this effect did notdamage tbe slip cast, because the special plaster casthad been cut before sintering. The sititered coping,whieh was removed easily from the special plaster cast,bad an excellent marginal fit. It had a chalkhke con-sistency and could be remodeled easily. Powder par-tieles of colored glass from the Vita shade system weremixed with distilled water and brushed onto the sur-faces of the coping. The inner surfaces of the copingwings, which are responsible for the bonding to theenamel, and the basis of the pontic excluded from theabove-mentioned procedure, Tben the coping, coatedwith glass powder, was placed on a platinum foil andftred in the Vita Inceramat at a temperature of 1100 °Cfor 4 hours. During thts process, the melting glassinfiltrates the sintered coping completely (Fig 13). Aft-er the infiltratton firing, excess glass was removed withaluminum oxide powder air abrasion.

To finish the In-Ceram resin-bonded fixed partialdenture, the coping was veneered with Vitadur-N ce-ramic material (Vita Zahnfabrik) (Figs 14 and 15),After the try-in of the all-porcelain, resin-bonded pros-thesis, the inner surfaces of the coping wings were airabraded with aluminium oxide particle and coatedwith silane to increase the bonding strength with theluting cement.'^

The abutment teeth and the adjacent teeth were cov-ered with a rubber dam (Fig 16). The abutment teetbwere cleaned with a rotating rubber cup and nonfluor-idated pumice. Then they were conditioned witb anacid-etching gel (37% phosphoric acid) for 60 sec-

onds, rinsed with water spray, and dried with air pres-sure. Then ihe fixed partial denture was inserted andcemented with Panavia Ex luting cement (KurarayCo), After 15 minutes, excess resin cement was re-moved with fine rotating diamonds. Then the neees-sary ocelusal corrections were performed. Two daysafter insertion, the margins of the In-Ceram resin-bonded bridge were pohshed (Figs 17 and 18).

Discussion

In-Ceram is a newly developed aluminum oxide ce-ramic with physical properties better than those ofotber ceramic or glass materials."'"'- Claus" sbowedthat the flexural strength of ln-Ceram is three to fourtimes higher than that of traditional ceramic mate-rials. When In-Ceram is used, developing microcrackscannot spread out because of the intense contact be-tween the aluminum oxide grains. Therefore, it can beexpected that all-porcelain, resin-bonded prostbesesmade out of In-Ceram will bave a good prognosis iftreatment protocol is respected. The minimal thick-ness of the retainer wings should be 0.5 mm"; toachieve this goal, sufficient space must be present,either because of overjet that is present or because oftootb preparations. Deep bite situation and brnxismare contraindications to use of this technique.

This material appears to provide esthetic and func-tional fixed partial dentures. However, long-term clin-ical experiences with In-Ceram and the described tech-nique for resin-bondcd prostheses are not availableyet.

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Ackaowledgtnent

The authors thank Dr H, F, Kappert, Chairman of Dental Mate-rials, Albert-Ludwigs University, Tor his advite and technical as-sistance.

References

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15, Kern M, Schwarzbach W, Strub JR: In vitro stability of resinbonded all-porcelain bridges (In-Ceram), Presented at the 27thAnnual Meeting of the International Association for DentalResearch, Continental European Division, Berne, September1990- Ü

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