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AbstractThe patients interested in physiognomic restorations

may choose from among a large range of available mate-rials and techniques. The full-ceramic systems usingzirconia, combined with the CAD-CAM technology, al-low the realization of full-ceramic restorations in any areaof the dental arch. Their particular qualities - aesthetic,biological, strength, shearing, elasticity, capacity of pre-venting fissure propagation, simple cementation tech-nique – strongly recommend these materials in every daystomatological practice.

The paper describes a case study devoted to the utili-zation of zirconia as a support material for ceramic resto-rations, combined with the CAD-CAM technique, of atooth in the frontal aesthetic zone.

Keywords: zirconia, CAD -CAM, aesthetic anterior area

INTRODUCTION

The aesthetics of the frontal zone assumesintegration of both colour and of each compo-nent – facial, dento-facial, dental, gingival andfunctional – of the smile. (1)

Patients interested in physiognomic restora-tions may choose from among a large range ofavailable materials and techniques. The full-ce-ramic systems using zirconia, combined with theCAD-CAM technology, allow the realization offull-ceramic restorations in any area of the den-tal arch. The working technique is based on pre-paring the skeleton of the prosthetic structuresmade of ceramic blocks, and subsequently cov-ered with a specially-designed ceramic mass.The first ceramic blocks available on the marketare the alumina ones, the more recent ones beingthe zirconia. The support of the prosthetic workis obtained by means of certain computer pro-grams which establish the shape and sizes of thefuture restoration. (2)

THE CAD-CAM TECHNOLOGY AND THE ZIRCONIA-BASED SYSTEMSIN THE FRONTAL AESTHETIC AREA. A CASE STUDY

Mona Ionas1, Mariana Sabau2, T. Ionas3

1 Lecturer, „Victor Papilian” Faculty of Medicine, „Lucian Blaga” University of Sibiu2 Assist. Prof., „Victor Papilian” Faculty of Medicine, „Lucian Blaga” University of Sibiu3 Dental specialist doctor, S.C. AMIC S.R.L., SibiuCorresponding author: Mona Iona[, e-mail monaionas@yahoo.com

MATERIALS AND METHOD

F.D., a 25 year-old patient, came to the dentalsurgery to have replaced a fractured acryliccrown with subgingivally-situated margins,made several years ago for the non vital 11 tooth.

Case analysis shows the triangular shape ofthe teeth in the frontal area, with a flat incisalimage and pronounced incisal angles, main-tained teeth proportion, normal bending of thedental axes, moderate texture, normal occlusionin all planes of the frontal zone. At the level ofthe marginal periodontium, a symmetrical con-tour may be noticed, with a Gal class I aestheticline, a thick biotype, with no inflammation,hypertrophy or recession, and normally-shapedgingival papillae.

An integrally-ceramic crown with a zirco-nium oxide support was designed, in coopera-tion with the patient.

Impressing of the prosthetic field and of theworking model was performed by the classicalmethods in use. The working model wasscanned with the specialized equipment of theCercon system, the „Cercon eye” (Degussa Den-tal GmbH, Germany), while the digital process-ing of data, for the realization of the zirconiumskeleton, was performed with the „Cercon art”program. Burring was made with “Cerconbrain”, from a block of zirconium oxide ceram-ics. The advantage of the industrially-made ce-ramic block is its homogeneous, non-porousstructure. Presinterized ceramics was used,which required its subsequent sinterization. Theprosthetic work is burred so that, aftersinterization, the final dimensions are obtained.Sinterization was made in a „Cercon heat” oven

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Prosthetic Dentistry

International Journal of Medical Dentistry 195

and final layering with IPS e.max Ceram (IvoclarVivadent) shade A2. (fig.1). Cementing wasdone by the classical technique.

RESULTS

An excellent aesthetic and functional restora-tion was achieved, the patient being reallyhappy. (fig. 2)

Fig. 2. Aspect of pacient after application of theintegrally-ceramic crown on 1.1

a) b)

c) d)

e)

Fig. 1. Apects of the integrally-ceramic crown: a) designing of zirconia caping, b) cape aspect immediatelyafter burring, c) zirconium cape prepared for burning, d) application of implanting ceramics,

e) final aspect of the prosthetic work

THE CAD-CAM TECHNOLOGY AND THE ZIRCONIA-BASED SYSTEMSIN THE FRONTAL AESTHETIC AREA. A CASE STUDY

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DISCUSSION

Nowadays, available on the market are fourlarge classes of ceramic materials: feldspathpowder/liquid porcelains, ceramics eitherpressed or processed with glass particles, crys-talline ceramics with increased resistance(alumina- and zirconia-based systems), metalo-ceramics.

Considering its characteristics and followingthe recommended indications, the material se-lected for the study was ceramics made of zirco-nium oxide. Once known that the experimentsinvolved removal of a considerable amount ofdental structure, a highly resistant ceramics waspreferred. More than that, the margins of thepreparation were situated subgingivally, beingknown that any zirconia device applied on theskeleton will assure a better marginal closing atthis level. For obtaining a maximum aestheticeffect, capable of hiding the colour modificationsoccurring in the dental substratum, a 1.5 mmspace should be created for the ceramic masses.

Ceramics with increased resistance is indi-cated when a significant part of the dental struc-ture is missing, an unfavourable factor of flexionand distribution of stress being thus present.(3)

The elasticity modulus and the bending re-sistance of the zirconium oxide ceramics arecomparable with those of the CoCr alloys,(4),showing a bending and fracture resistance supe-rior to those of the other integral ceramics, (5)the presence of zirconia being also capable ofinhibiting fissure propagation, which reducesthe risk of therapeutical failure.(6)

The zirconia-based systems are highly bio-logically-integrated, as they do not suffer addi-tional oxidation, showing only reduced accumu-lation of bacterial plaque (7,8), and goodcharacteristics of light optics.(4)

In achieving integrally-ceramic restorationswith zirconium oxide skeleton, of special impor-tance is the selection of the type of ceramics usedfor the plaque, a correct establishment of itsthickness, and modelling of the anatomo-shap-ing of the zirconium dioxide skeleton.(7,8)

In this clinical case, classical crown cement-ing was performed, considering that other stud-ies reported that fracture strength is excellent,whichever the type of cementation system ap-plied: adhesive or classical. (9)

CONCLUSIONS

The CAD-CAM technology, applied togetherwith zirconia systems, represents an excellentoption for exigent physiognomic restorations.

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Culic B., Iona[ T., Smarandache A., Sas A.,“No]iuni introductive de estetic\ în medicinadentar\: note de curs.”, Editura Universit\]iiLucian Blaga, Sibiu, 2010;

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3. Mc Laren E.A., Whiteman Y.Y.,”Cerammics:Rationale for Material Selection” ,Compendium 2010, 31(9), pag. 666-680;

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Mona Ionas, Mariana Sabau, T. Ionas