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Implant-supported prostheses have been used extensively to rehabilitate completely edentulous arches. Althoughcombinations of different restorative materials have reportedly been used to fabricate such prostheses, a metal frame-work is usually chosen for acrylic resin reinforcement. However, cost and the frequent need to section and solder toattain a passive framework fit are disadvantages for using metal. Zirconia has been used widely in restorative dentistryas an alternative to metal. This clinical report describes the fabrication of a zirconia-reinforced cementable fixed den-

tal prosthesis with a 4-year follow-up. (J Prosthet Dent 2012;108:138-142)

Four-year follow-up of the rehabilitationof a mandibular arch with a cementablezirconia-reinforced fixed dentalprosthesis: A clinical report

Abdulmohsin Alhashim, BDS, MSD,a Mohamed Kamel, BDS,

MSc, MSD,b and William W. Brackett, DDS, MSDcCollege of Dental Medicine, Georgia Health Sciences University,Augusta, Ga; New Jersey Dental School, University of Medicineand Dentistry of New Jersey, Newark, NJ

aAssistant Professor, Department of Oral Rehabilitation, College of Dental Medicine, Georgia Health Sciences University.bAssistant Professor, Department of Restorative Dentistry, New Jersey Dental School, University of Medicine and Dentistry of New Jersey.cProfessor, Department of Oral Rehabilitation, College of Dental Medicine, Georgia Health Sciences University.

The restoration of completely

edentulous arches with implant-sup-

ported prostheses is a predictable

treatment modality.1-3 The choice of

restorative materials and the occlu-

sal scheme for implant-supported

prostheses is generally determined

by the opposing arch. In treatments

where the opposing arch is restored

with a complete denture, a bilateral

balanced occlusal scheme and a re-

inforced acrylic resin prosthesis are

recommended.4-7 Usually, metal is

used to reinforce such prostheses.

Distortion from heating and cooling

during the lost wax casting technique

may make it necessary to section and

solder the framework to obtain a pas-

sive fit. Affordable base metal alloys

cannot be soldered reliably,8 while the

cost of noble metals, which can be

soldered adequately, is prohibitive.The development of computer-

aided design/computer-assisted man-

ufacturing (CAD/CAM) introduced

milled frameworks with significantly

better fit than conventional castings.9

Zirconia has been used extensively

for milled cementable frameworks

that have a lower fabrication cost

than cast frameworks. The use of a

device to verify the accuracy of im-

plant positions on the definitive cast

is recommended because section-

ing and soldering of milled zirconia

frameworks is not possible. Acrylic

resin is attached to cast metal with

mechanical retention, produced by

the addition of beads and strips to

the wax pattern to obtain undercuts.

Undercuts are not easily milled into

zirconia frameworks, and cutting un-

dercuts into the framework after milling

reduces their strength; the framework,

therefore, must be designed to allow

encirclement by the acrylic resin. When

a metal framework is used to reinforce a

prosthesis, an opaque layer is required

to mask the metal color; however, the

opaque layer is not needed for a zirconia

framework. This clinical report demon-

strates the fabrication of a cementablefixed dental prosthesis by using a zirco-

nia framework and acrylic resin.

CLINICAL REPORT

A 55-year-old white male present-

ed for treatment complaining that he

could not wear a mandibular denture.

He expressed a desire for a fixed man-

dibular restoration and also needed a

new maxillary denture. A review of the

patients medical history revealed no

significant findings. Although unable

to wear a mandibular complete den-

ture because of lack of retention and

stability, the patient had successfully

worn a maxillary complete denture for

approximately 10 years.The maxillarysoft tissues appeared firm posteriorly

and slightly displaceable anteriorly,

with evidence of mild inflammation

due to an ill-fitting denture. The pa-

tient had a well-developed mandibu-

lar ridge (Figs. 1, 2). The mandibular

ridge and tongue size provided lim-

ited space for denture flanges, which

compromised retention and stability.

The patient was instructed to

stop wearing the maxillary complete

denture for 48 hours and finger mas-sage the tissue frequently with gauze

moistened with water. Tissue condi-

tioner (Visco-gel; Dentsply Intl, York,

Pa) was applied to the intaglio surface

of the maxillary complete denture.

Maxillary and mandibular preliminary

impressions were made with irrevers-

ible hydrocolloid impression material

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139September 2012

Alhashim et al

(Jeltrate; Dentsply Intl) in stock metal

trays (CEO; GC America, Alsip, Ill).

The impressions were poured with

Type III dental stone (Microstone;

Whip Mix, Louisville, Ky).

Record bases were fabricated with

acrylic resin (Triad Tru Tray; Dentsply

Intl) and occlusion rims were added

by using baseplate wax. A tentativeocclusal vertical dimension was es-

tablished. A centric relation record

was made with impression wax (Alu-

wax; Benco Dental, Pittston, Pa), and

a facebow transfer (Hanau Spring-

Bow; Whip Mix Corp) was made.

The maxillary diagnostic cast was

mounted on an articulator (Hanau

Wide Vue; Whip Mix Corp) with Type

III mounting stone (Mounting Stone;

Whip Mix Corp). The mandibular di-agnostic cast was mounted by using

the centric relation record.

Esthetics and phonetics were used

to establish the position of the anteri-

or teeth. Centric relation was verified

with an additional centric relation re-

cord. A protrusive record was made

to program the articulator settings

for the horizontal and lateral condy-

lar indications. Denture teeth (SR Or-

tholingual DCL; Ivoclar, Amherst, NY)

were selected to develop a balanced,

lingualized occlusal scheme since the

maxillary dentition was provided by a

complete denture. The occlusion and

esthetics were verified at the trial in-

sertion appointment. The mandibu-

lar diagnostic wax trial denture was

duplicated in orthodontic acrylic res-

in (Dentsply Caulk, Milford, Del) to

fabricate a surgical guide for implant

placement.

Six implants (4.7 13 mm; Zim-mer Dental, Carlsbad, Calif) were

surgically placed in the mandible

and allowed to heal for 4 months.

The implants were uncovered and an

open tray implant-level impression

was made in medium-body polyether

impression material (Impregum; 3M

ESPE AG, Seefeld, Germany). Two

temporary abutments (Zimmer Den-

tal) were screwed into the 2 implants

in the mandibular canine locations.The surgical guide was hollowed

out to create room for acrylic resin

around the temporary abutments.

The maxillary diagnostic wax trial

denture and the mandibular surgical

guide were placed into occlusion to

verify complete seating of the surgical

guide. Autopolymerized acrylic resin

(Pattern Resin; GC Corp, Tokyo, Ja-

pan) was injected around the 2 tem-

porary abutments to attach them to

the surgical guide. The patient again

was guided into centric occlusion to

confirm complete seating.A centric relation record was made

with modeling plastic impression

compound (Impression Compound;

Kerr Corp, Orange, Calif). The surgi-

cal guide with the 2 temporary abut-

ments was unscrewed and removed

from the patients mouth in 1 piece.

Implant analogs were connected to

the impression copings and gingival

moulage (Gi-Mask; Coltene/Whale-

dent, Inc, Cuyahoga Falls, Ohio) wasinjected around the junction of the im-

pression copings and the analogs. The

impression was poured with Type IV

dental stone (Microstone; Whip Mix

Corp). A verification index made of

autopolymerized acrylic resin (Pattern

Resin; GC Corp) and 6 nonengaging

temporary abutments were evaluated

intraorally to verify the accuracy of the

mandibular definitive cast.

The flanges were removed from the

mandibular surgical guide. The surgi-

cal guide was screwed onto the man-

dibular definitive cast by using the 2temporary abutments. Then the man-

dibular definitive cast was mounted

to the maxillary diagnostic cast by

using the centric relation record. The

articulator, the maxillary diagnostic

wax trial denture, and the mandibu-

lar surgical guide screwed onto the

mandibular definitive cast were sent

to a processing center (Atlantis Incor-

poration, Cambridge, Mass) to fabri-

cate titanium custom abutments. Theabutments were evaluated intraorally

1 Pretreatment radiograph.

2 Pretreatment mandibular arch.

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The Journal of Prosthetic Dentistry Alhashim et al

to verify the margins of the abut-

ments relative to the soft tissue (Fig.

3). The margins were maintained no

more than 1 mm below the tissue

margin to facilitate complete removal

of any excess cement. The abutments

were scanned by using a CAD/CAM

touch-probe scanner (Forte; Nobel

Biocare, Mahwah, NJ) to fabricate a

cementable zirconia framework.

The fit of the zirconia frameworkwas confirmed with disclosing mate-

rial (Fit Checker; GC Corp) (Fig. 4).

The mandibular teeth were attached

to the zirconia framework by using a

labial index made from the surgical

guide, which was a duplicate of the

original diagnostic treatment. The

wax was wrapped around the zirconia

framework. The wax trial prostheses

were evaluated intraorally and evalu-

ated for esthetics, phonetics, the ver-tical dimension occlusal, and centric

relation. The patient approved the

appearance of the prostheses and

signed the patient record to confirm

his acceptance. A centric relation re-

cord was made intraorally with mod-

eling plastic impression compound to

form an occlusal stage.

A maxillary definitive impression

was made with a tissue conditioning

material (Visco-gel; Dentsply Intl) by

closing gently into the occlusal stage.The maxillary definitive impression

was poured with Type IV dental stone

(Microstone; Whip Mix Corp). The

new maxillary definitive cast (within

the relined maxillary denture impres-

sion) was mounted against the man-

dibular definitive cast by using the

centric relation record. A facebow

preservation index was fabricated.10

The maxillary wax trial denture was

flasked and processed convention-ally with denture resin (Lucitone 199;

Dentsply Intl). The inner surfaces of

the zirconia framework were lubri-

cated with petroleum jelly and filled

with autopolymerized acrylic resin

and dowel pins and poured in stone

to make a new mandibular cast (man-

dibular processing cast). The man-

dibular processing cast was flasked

and processed with denture resin

(Lucitone 199; Dentsply Intl). The

processed mandibular prosthesis wasdeflasked, removed from the process-

ing cast, and placed on the defini-

tive cast. A laboratory remount was

performed to correct any processing

error. The prostheses were removed

from the casts, finished, and polished

(Figs. 5, 6).

The maxillary denture was insert-

ed and pressure indicating paste (PIP;

Mizzy Inc; Myerstown, Pa) was used

to verify complete seating. The bor-ders were evaluated with disclosing

3 Milled titanium abutments placed intraorally.

5 Completed prosthesis.

4 Zirconia framework evaluation.

6 Completed prosthesis, intaglio surface.

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141September 2012

Alhashim et al

wax (Kerr Corp) and adjusted accord-

ingly. The abutments were torqued to

30 Ncm. The relationship of the inta-

glio surface of the mandibular pros-

thesis to the soft tissue was evaluated

with the pressure indicating paste

(PIP; Mizzy) and adjusted according-

ly. Disclosing material, explorers, and

radiographs were used to confirmcomplete seating of the mandibular

prosthesis. A centric relation record

was made with modeling plastic im-

pression compound on the mandibu-

lar prosthesis, and the mandibular

remount cast was mounted against

the maxillary denture. A new centric

relation record was made to verify the

remounted prostheses. Selective grind-

ing was performed to refine the bal-

anced lingualized occlusal scheme. Themandibular prosthesis was cemented

with provisional implant cement (Pre-

mier Implant Cement; Plymouth Meet-

ing, Pa). The occlusion again was veri-

fied intraorally (Fig. 7).

Instructions on how to use and

maintain the prostheses were given

to the patient. The use of super floss

(Oral-B, Inc, Iowa City, Iowa) and a

water jet (Water Pik, Inc, Fort Col-

lins, Colo) to clean underneath the

mandibular prosthesis was demon-

strated to the patient. The patient

was seen after 24 hours and minor

adjustments were made. It was ex-

plained to the patient that the max-

illary complete denture would need

to be relined or remade in the future

and should be done when required to

maintain healthy, physiologic tissue

and minimize bone resorption. Recall

was scheduled every 6 months, and a

maxillary reline was performed after 3years. The 4-year evaluation is seen in

Figures 8 and 9. The positive attitude

of the patient and his satisfaction

with the treatment that addressed his

chief complaints and desires contrib-

uted to a good prognosis (Fig. 10).

SUMMARY

The combination of a zirconia

framework with acrylic resin to fabri-cate an implant-supported fixed den-

7 Completed prosthesis in occlusion.

9 Occlusal view of prosthesis, 4-year follow-up.

8 Prosthesis in occlusion, 4-year follow-up.

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The Journal of Prosthetic Dentistry Alhashim et al

tal prosthesis appears to be a satisfac-

tory treatment option. A cementable

implant-supported prosthesis has

advantages that include the preserva-

tion of intact occlusal surfaces andthe buffer effect of a cement layer that

helps with passive fit.

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3. Adell R, Eriksson B, Lekholm U, BrnemarkPI, Jemt T. Long-term follow-up study ofosseointegrated implants in the treatmentof totally edentulous jaws. Int J Oral Maxil-lofac Implants 1990;5:347-59.

4. Reitz JV. Lingualized occlusion in implant

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6. Sadowsky SJ. The implant-supported pros-thesis for the edentulous arch: design con-siderations. J Prosthet Dent 1997;78:28-33.

7. Nikolopoulou F, Ktena-Agapitou P. Ratio-nale for choices of occlusal schemes forcomplete dentures supported by implants. JOral Implantol 2006;32:200-3.

8. Anusavice KJ, Okabe T, Galloway SE, HoytDJ, Morse PK. Flexure test evaluation ofpresoldered base metal alloys. J Prosthet

Dent 1985;54:507-17.9. Drago C, Saldarriaga RL, Domagala D,

Almasri R. Volumetric determination of theamount of misfit in CAD/CAM and castimplant frameworks: a multicenter labora-tory study. Int J Oral Maxillofac Implants2010; 25:920-9.

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Corresponding author:

Dr Abdulmohsin AlhashimDepartment of Oral RehabilitationCollege of Dental MedicineGeorgia Health Sciences University1430 John Wesley Gilbert AveAugusta, GA 30912Fax: 706-721-8349E-mail: aalhashim@georgiahealth.edu

AcknowledgmentsThe authors thank Dr Robert Flinton and MsEva Bober for guidance in the clinical andtechnical aspects throughout the treatment.

Copyright 2012 by the Editorial Council for

The Journal of Prosthetic Dentistry.

10 Posttreatment radiograph.

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