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1In previous years, CoCr alloys were primarily used forPD frameworks. Currently, they are also used moreommonly than NiCr alloys for fixed prostheses.7 CoCrlloys contain predominantly cobalt, and sometimesungsten in small amounts, and possess high rigidity

congenitally missing and replaced by the canines, labialversion and rotation of the maxillary incisors, with largeembrasures present, and the presence of mandibularRPD extracoronal clasp retainers, which negativelyaffected esthetics (Fig. 1).

Clinical and radiographic examination confirmedlabial version of the maxillary incisors with periodontalinvolvement of the teeth. The patient was partially eden-tulous, and the following teeth were absent in the max-illa: right and left lateral incisors, right second premolar,left canine, first premolar, and first molar. The mandib-ular left first premolar, first and secondmolars, right sec-ond premolar, and first molar were also missing.Numerous existing fixed prostheses were also noted:

ssociate Professor, Department of Prosthodontics, Faculty ofOdontology, Claude Bernard University Lyon I.rofessor, Research Director, Institut National Polytechnique deGrenoble.rofessor, Department of Prosthodontics, Faculty of Odontology,Claude Bernard University of Lyon I; Dental Clinic, HospicesCivils de Lyon.ssociate Professor, Department of Biomaterials, Faculty of Odon-tology, Claude Bernard University Lyon I.Combination fixed and removable proA clinical report

Stephane Viennot, DDS,a Francis Dalard, PhDBrigitte Grosgogeat, DDS, PhDd

Faculty of Odontology, Claude Bernard UniverCivils de Lyon, Lyon, France; Institut National P

It is now possible to provide combination fixed/ralloy, such as CoCr, a nonprecious alloy. This alloysion resistance. This clinical report demonstrates usdentures in conjunction with a mandibular remova

Irrespective of many encouraging reported advancesin the field of materials science using all-ceramic systemssince the early 1980s,1 alloys are still used extensively forinfrastructures of ceramic restorations, especially in fixedprosthodontics.2 Historically, precious alloys have beenused most frequently, but the popularity of base metalalloys has increased since the 1970s.3 Base metal alloyshave demonstrated good clinical performance and re-sistance to permanent intraoral deformation in mostclinical situations.4 The high elastic modulus and hard-ness of base metal alloys are adequate for long-spanmetal-ceramic restorations or removable partial den-tures (RPDs). The mechanical properties of base metalalloys and low cost make them attractive. Potential bio-logical hazards and difficult handling characteristics re-main their primary disadvantages.5,6

Clinicians have promoted the use of NiCrMo,CoCrMo, or CoCrW nonprecious base metal alloys.Apart from economic reasons, they have become in-creasingly used, predominately in removable prostho-dontics and, to a lesser degree, in fixed prosthodontics.Frameworks can be made thinner, are 40% to 50%more rigid than precious alloys, and are significantlylighter than precious alloys (nearly 8 g/cm3 comparedto 15 g/cm3 for precious alloys).5 The presence of chro-mium (nearly 20%), tungsten (nearly 5%), and molyb-denum ensures biocompatibility and high resistance tocorrosion.400 THE JOURNAL OF PROSTHETIC DENTISTRYstheses using a CoCr alloy:

,b Guillaume Malquarti, DDS, PhD,c and

sity of Lyon I, Lyon, France; Dental Clinic, Hospicesolytechnique de Grenoble, Grenoble, France

emovable prosthetic restorations using only 1 dentaloffers clinical performance and demonstrated corro-

e of a single CoCr alloy for metal-ceramic fixed partialble partial denture. (J Prosthet Dent 2006;96:100-3.)

and hardness.8 Electrochemical studies show that CoCralloys are more resistant to corrosion than NiCr al-loys.9-11 Nickel-based alloys also have a greater sensiti-zation potential than cobalt chromium alloys, whereasCoCr alloy allergies are rare.12,13 Furthermore, thecasting of CoCr alloys has become a routine proce-dure in dental laboratories.14

Biocompatibility and mechanical properties for an al-loy used for a dental prosthesis depend both on the ma-terial and correct processing during fabrication. Giventhe desire to eliminate and/or minimize possible gal-vanic corrosion that may occur with the use of multiplealloys in restorations for a patient, the use of a singleCoCr alloy for components of a complex reconstructionmay be advantageous. Disadvantages of such a choiceare complex laboratory procedures, such as additionalcasting and good metallurgical knowledge regardingthe various uses of a single alloy. This clinical report illus-trates the use of CoCr alloy for both fixed and removableprostheses for a patient.

CLINICAL REPORT

A 40-year-old woman was referred by her dentistto the Department of Prosthodontics, Dental Clinic,Hospices Civils of Lyon, France, for prosthodontic con-sultation and to address the esthetic concerns of the pa-tient. These included maxillary lateral incisors that wereVOLUME 96 NUMBER 2

THE JOURNAL OF PROSTHETIC DENTISTRYVIENNOT ET ALa maxillary fixed partial denture (FPD) with cantileveredleft canine, 2 crowns on the maxillary right and themandibular left second premolars, and a mandibularconventional RPD replacing the left first premolar, firstand second molars, right second premolar, and first mo-lar (Figs. 2 and 3). The intercuspal position was deter-mined to be unstable given the excessive vertical andhorizontal overlap of incisors and canines (Fig. 4).

Onlyonemaxillary treatmentoptionwas offered to thepatient to satisfy her functional and esthetic needs. Thepatient expressed a desire to retain as many of her maxil-lary incisors and canines for as long as possible. Therefore,the patient agreed to a periodontal and orthodontic treat-ment, and expressed a desire to retain the remaining teethand restore with amaxillary singlemetal-ceramic FPD ex-tending from the right second molar to left first molar(Fig. 5). Two mandibular treatment options were dis-cussed: a bilateral mandibular implant-supported fixedprostheses after extraction of the mandibular left secondpremolar, or a single metal-ceramic crown (mandibularright second molar) and a mandibular RPD retainedby an 8-unit mandibular metal-ceramic FPD from the

Fig. 1. Pretreatment frontal view.

Fig. 3. Pretreatment view of mandibular arch.AUGUST 2006mandibular left second premolar to the mandibular rightfirst premolar, including semiprecision attachments tosplint the teeth following orthodontic treatment.

The patient rejected the placement of implantsbecause of the need for additional surgery and theunacceptable duration of the treatment phase. Thetreatment plan selected included periodontal surgerywith open flap debridement to treat periodontal bonydefects, and orthodontic treatment to align teeth andimprove the sagittal and vertical dental relationshipsand facial esthetics to create a more favorable startingpoint for the prosthodontic phase. The orthodontictreatment was provided using a standard straight-wireappliance,15 including vestibular multiwired braces(Dentaurum, Ispringen, Germany). Abutments for themetal-ceramic crowns were prepared supragingivallydue to the thin marginal tissues following periodontalsurgery. Pulp vitality was maintained for all the teethwith an emphasis on conservative tooth preparations.A single nonprecious CoCr alloy (Remanium 2000;Dentaurum) was selected as the metal for all the metal-ceramic restorations and for the mandibular RPD

Fig. 2. Pretreatment view of maxilla.

Fig. 4. Pretreatment view of teeth in occlusion. Note exces-sive vertical and horizontal overlap.101

VIENNOT ET ALframework. This alloy was chosen because of its low co-efficient of thermal expansion and low hardness.16 Themandibular FPD included semiprecision attachments(CPA semi-precision attachments; Servo-Dental, Ha-gen, Germany). The mandibular RPD design included1 retentive clasp on the right second molar and 2attachments without clasps on the left second premolarand the right first premolar (Fig. 6). All abutmentswere designed with occlusal rests and guiding planes toincrease retention and provide stabilization. The maxil-lary and mandibular FPD frameworks were cast in a sin-gle piece and verified for fit. Then, the ceramic material(IPS; Ivoclar Vivadent, Schaan, Liechtenstein) was ap-plied to the frameworks, the restorations were onceagain verified for fit, and equilibrated occlusally. Next,the mandibular RPD framework was cast and verifiedfor fit (the matrix portions of the attachments were in-corporated into the framework). Then, artificial teeth(SR Postaris; Ivoclar Vivadent) were arranged and es-thetics,maxillomandibular relations, stability, andocclu-sion were verified intraorally (Fig. 7). The mandibular

Fig. 5. Maxillary fixed partial denture.

Fig. 7. Post-treatment view of mandible. Fixed and remov-able partial dentures with attachments.

THE JOURNAL OF PROSTHETIC DENTISTRY102RPD was processed with heat-polymerized acrylic resin(Ivocron; Ivoclar Vivadent). Subsequently, the FPDswere cemented with glass-ionomer cement (Fuji I; GCCorp, Tokyo, Japan).

The patient was monitored at 5-month intervals for2 years, and once each year thereafter. Eight years afterplacement, the patient acknowledged a general feelingof comfort and showed no biological incompatibility(no allergy, gingival discoloration, burning feelings, ortingling) or corrosion of the prostheses. This treatmentmaintained pulp vitality, restored function, and wasesthetically satisfactory (Fig. 8).

SUMMARY

The dental profession has used gold-based alloys suc-cessfully for many years. However, because of cost, theuse of nonprecious alloys has increased. Questions re-main about the biological compatibility and corrosionsusceptibility, particularly regarding NiCr alloys. TheCoCr nonprecious alloy described in this clinical report

Fig. 6. Attachment and RPD restoring tooth contour.

Fig. 8. Prostheses 8 years after insertion.VOLUME 96 NUMBER 2

as a single alloy used for fixed and removable prostho-dontics avoided the disadvantages of NiCr alloys.

Special thanks to Laboratoire de Prosthe`se PFEFFER, 69 Dardilly,

France.

CONTRIBUTING AUTHOR

Michele Lissac, DDS, PhD, Professor, Department of Biomate-

rials, Faculty of Odontology, Claude Bernard University Lyon I.

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4. Craig RG, Powers JM. Restorative dental materials. 7th ed. St. Louis:

Mosby; 2002. p. 128.

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7. Taher NM, Al Jabab AS. Galvanic corrosion behavior of implant supra-

structure dental alloys. Dent Mater 2003;19:54-9.

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the corrosion of dental metal alloys. J Oral Rehab 2000;27:563-75.

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Quintessence Int 1996;27:513-20.

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a review of the method and comparisons of the equipment. J Oral Rehabil

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treatment. In: Host, et al, editors. Orthodontics and periodontics. Chi-

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Braz Dent J 2005;16:50-5.

Reprint requests to:

DR STEPHANE VIENNOT

LABORATOIRE DETUDE DES INTERFACES ET DES BIOFILMS EN ODONTOLOGIE (EA 637)

FACULTY OF ODONTOLOGY, CLAUDE BERNARD UNIVERSITY OF LYON I

RUE GUILLAUME PARADIN

69372 LYON CEDEX 08

FRANCE

FAX : 0033-478-77-8696

E-MAIL: stephane.viennot@wanadoo.fr

0022-3913/$32.00

Copyright 2006 by The Editorial Council of The Journal of ProstheticDentistry.

doi:10.1016/j.prosdent.2006.04.013

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THE JOURNAL OF PROSTHETIC DENTISTRYVIENNOT ET ALInterproximal papillaof single-tooth implaSchropp L, Isidor F, KImplants 2005;20:753

Purpose: The aim of this study was to evaluate interproplacement of single-tooth implants according to early aMaterials and Methods: Forty-five patients were randelayed group. They were treated with a single-toomandibular anterior or premolar region an average of(in the case of delayed placement) following tooth extcrown height were evaluated using a score index in 3months after prosthesis delivery. The patients were eplacement (baseline) and approximately 1.5 years afterResults: It was demonstrated by logistic regression the7 times greater at baseline for delayed cases than for eain the proximal spaces improved significantly from basno significant difference between the groups found aimplant placement was inversely correlated with patiesignificantly more cases in the early group than in the ddelayed group exhibited an inappropriate height; of theDiscussion and Conclusion: Early placement of singleplacement technique in terms of early generation ofappropriate clinical crown height, but no difference inof the implant crown.Reprinted with permission of Qu

Noteworthy Abstractsof theCurrent LiteratureAUGUST 2006levels following early versus delayed placementts: A controlled clinical trialostopoulos L, Wenzel A. Int J Oral Maxillofac61.

imal papillae and clinical crown height following thed delayed protocols.domly allocated to either the early group or theth acid-etched Osseotite implant in the maxillary or0 days (in the case of early placement) or 3 monthsaction. Interproximal papilla dimensions and clinical9 patients who attended a follow-up visit 16 to 18valuated in photographs taken 1 week after crownrown placement (follow-up).risk of presenting no papilla or a negative papilla wasly cases (33% versus 8%). However, the soft tissue fillline to the 1.5-year follow-up in both groups, withfollow-up. The papilla height almost 2 years aftert age. The clinical crown height was acceptable inelayed group at follow-up. Half of the crowns in these, almost two thirds were assessed to be too short.tooth implants may be preferable to delayed implantinterproximal papillae and the achievement of anapilla dimensions was seen at 1.5 years after seatingintessence Publishing.103

Combination fixed and removable prostheses using a CoCr alloy: A clinical reportClinical reportSummaryContributing authorReferences