TREATMENT OF ABRADED TEETH USING METAL FREE CERAMICS AND CONVENTIONAL METAL-CERAMIC RESTORATIONS

Sažetak Uvod. Savremena rekonstruktivna stomatologija se smatra bioestetskom disciplinom, učenjem o lepoti živih bića i izvornom obliku i funkcijama. Diskutovati o estetskoj stomatologiji, vrhunskim veštačkim nadoknadama u ustima pacijenta, teško prepoznatljivim za oko posmatrača, sublimira niz kvaliteta. Gubitak tvrde zubne supstance koji nije uslovljen karijesom je fiziološki proces koji je prisutan tokom celog života, ali pojedini faktori mogu dovesti do opsežnog gubitka tvrdog zubnog tkiva. Gubitak tvrdog zubnog tkiva je uslovljen kombinacijom raznih etioloških faktora, kao što su: genetski i funkcionalni. Prikaz slučaja. Pacijent dolazi u stomatološku ordinaciju i žali se na opsežan gubitak tvrdog zubnog tkiva, loš izgled svojih zuba, poremećaj govora, kao i na probleme pri mastikaciji. Intraoralnim pregledom je ustanovljeno postojanje izuzetne abrazije. Plan terapije je pojednostavio postupak kombinacijom klasičnih metalo-keramičkih restauracija i novog bezmetalnog keramičkog sistema IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein). Zaključak. Na ovom kliničkom slučaju sa prisutnom abrazijom prikazana je kombinovana terapija primenom bezmetalnih restauracija i standardnih metal-keramičkih nadoknada u cilju ponovnog uspostavljanja zdravlja, funkcije i estetike. Primenom restauracija od bezmetalne keramike sa osnovom od cirkonijuma (IPS e.max ZirPress, Ivoclar Vivadent, Schaan, Liechtenstein) moguće je postići besprekorne kliničke rezultate kako u frontalnom tako i u bočnom segmentu. Ključne reči: abrazija, metal-keramičke restauracije, bezmetalne keramičke restauracije


Prikaz slučaja
Pacijent dolazi u stomatološku ordinaciju i žali se na opsežan gubitak tvrdog zubnog tkiva, loš izgled svojih zuba, poremećaj govora, kao i na probleme pri mastikaciji.Pri ekstraoralnom pregledu nisu uočene nikakve nepravilnosti niti asimetrije.Pri otvaranju usta ustanovljena su pucketanja na obe strane, ali su granične kretnje donje vilice izvodljive i bez prisustva bolova u delu viličnih zglobova.Intraoralnim pregledom je ustanovljeno postojanje izuzetne abrazije (sl.1).Nije bilo praznih prostora kao posledica of living beings in their natural forms and with their natural functions.A discussion of esthetic dentistry, state-of-the-art artificial replacements in the patient's mouth, hardly discernible to an unexperienced eye, involves a sequence of qualities 1 .Natural appearance, functionality, and a perfect smile today are a permanent de mand in dentistry clinics.On the other hand, a very rapid development of therapeutic clinical procedures and restoration materials in den tistry make possible for us to offer our patients a wide array of therapeutic modalities 2,3 .In direct restorations made of metal free ceramics represent an approach of choice in the visible segment of teeth, but are increasingly used in the lateral segments as well.The development of materials and recent technical advances in dentistry increase the reliability of new metal free ceramic systems in the frontal and lateral segments.
In most patients, the use of new forms of indirect restorations, in addition to excellent esthetic results, can afford other significant advantages.We should mention the simplicity of clinical procedures and supragingival place ment of the crown edges, which exerts favor able effects on the parodontium 4 .Moreover, the use of composite cements increases retention.These specificities are extremely important in the treatment of large defects of hard dental tis sues, with the very common concomitant pres ence of untreated pathologic conditions, such as open bite and reverse overjet.
The loss of hard dental tissue, not caused by caries, is a physiologic process present through out our life, but some factors may lead to ex tensive losses of hard dental tissues.The loss of hard dental tissue, as in the clinical case we intend to present here, is the result of a combi nation of various etiologic factors, both genetic and functional 5,6 .
Ovaj kompozitni cement se u osnovi ba zira na klasičnim restaurativnim kompozitima.Sastoji se od monomera i neorganskih čestica punila.Vezivanje se bazira na unakrsnom povezivanju polimernih lanaca, koje se može inicirati hemijski ili putem svetla.Adhezivno cementiranje omogućava vezivanje restauracija kod kojih već postoji insuficijentna veza usled 15.In the next phase, final teeth preparations were made to bear metal free crowns, using the rounded step (1.0 mm) bur abrasion.The advan tage of IPSe.max metal free system used in this case was that excellent esthetic results could be achieved in a limited space and with little den tal tissue, since there was no need here to use an opaquer for metal coverage.The creation of rounded, smooth and precise preparations required special attention, since we wanted to prevent contact point overloads (fig.3 and 4).The possibility to place the preparation border at the gingival level facilitated the preparation and creation of a final impression.The impres sion was taken using a standard spoon and addi tion silicone (Virtual, Ivoclar Vivadent, Schaan, Liechtenstein).The casts of the upper and lower jaw were placed into the articulator after the transfer with a buccal arch.Determination of interjaw rela tionships was done in the central position using three wax registrations on the prepared upper and lower jaw teeth.After the try-in of metal free skeletons and metal frameworks, the color and final shape of the teeths were determined (fig.5 and 6).Metal-ceramic bridges were cemented with a glass-ionomer cement (Viva glas, Ivoclar Vivadent, Schaan, Liechtenstein), while metal free crowns were cemented using a composite cement (Multilink Automix, Ivoclar Vivadent, Schaan, Liechtenstein).
This composite cement is based on classical restoration composites.It consists of monomers and inorganic filling particles.The binding is based on the cross-linking of polymer chains, initiated chemically or by light.Adhesive ce menting enables binding of the restorations with insufficient binding ability due to small manjka retentivne površine, kao što je u ovom kliničkom slučaju.Navedeni sistem odab ran je zbog karakteristika univerzalnosti.Iako se ne smatra vrhunskim estetskim sistemom (izbor tri boje), jačina njegove veze je veća u poređenju sa drugim kompozitnim cementom.Ovaj kompozitni cement se sastoji od kompozi ta i Multilink Primer-a A i B. Sistem inicijatora omogućava hemijsku vezu (samoatherencija) koja je poboljšana kontaktom kompozita sa prajmerom.Postoji i mogućnost inicijacije svetlom, zbog prisustva odgovarajućeg fotosenzibilnog inicijatora.retention surfaces, as in this clinical case.The system was chosen for its universal characteris tics.Although it is not a top-notch esthetic sys tem (the choice of only three colors), its bond ing strength exceeds that of other composite cements.This composite cement consists of a composite and Multilink Primers A and B. The system of initiators enables chemical bonding (self-adherence), further improved by the com posite-primer contact.There is a possibility of light curing too, due to the presence of an ap propriate photo-sensitive initiator.Ceramic restorations are etched using the fluorohydric acid (IPS Ceramic etching-gel).After washing and drying, a bonding substance is applied (Monobond -S, Ivoclar Vivadent, Schaan, Liechtenstein) to the inner surface of the replacement and left for 60 seconds.After that the surfaces are air-dried.Multilink Primer liquids A and B are mixed in 1:1 ratio (one drop of primer A and one drop of primer B).The combined primer is then applied to the replace ment surface for 15 seconds.This cement type is applied to the restoration surface due to overacceleration of the process of bonding induced by the primer-composite contact.All the crown were illuminated for 20 seconds with a LEDlamp (Bluephase 16i, Ivoclar Vivadent, Schaan, Liechtenstein).fine retraction filaments were previously placed in the sulcus in order to achieve better control over the crown edge and to facilitate the removal of cement debris.for interdental cement debris to be removed, the fil aments soaked in glycerin were placed between the teeth to facilitate the removal.The patient was very satisfied with his natural appearance, function, and speech (fig.7).

Discussion
Although it appears that the use of metal free replacements in the routine practice of dentistry produces good results, long-term be havior of these new ceramic materials is still largely unknown.Consequentially, the already proven prosthetic solutions, such as conven tional metal-ceramic bridges, would represent a reliable alternative.Two most recent review papers have analyzed all the articles dealing with the success and complication rates of metal free bridges compared to metal-ceramic crowns 7 .The five-year success rate of full ce ramic crowns has been 93.3%, compared to 95.6% with metal-ceramic crowns.
In addition to basic biologic complications, the loss of pulp vitality has been equal to both full ceramic and metal-ceramic crowns, with the five-year rate of 2.1%.A five-year tooth loss rate with full ceramic crowns has been lower than that with metal-ceramic crowns (1.8% vs 3.2%) 8 .
The fundamental technical complication as sociated with full ceramic crowns has been the fracture of their base, while the rate of cracks in the ceramic layer in full ceramic crowns has been lower (3.7%)than that with metal-ceram ic crowns (5.7%).Compared to metal-ceramic bridges, metal free bridges have demonstrated the presence of the same biologic complica tions encountered in individual crowns made of the same material.In contrast, technical com plications have been more common in metal-Slika 7. Kompletna rehabilitacija Figure 7. Completed rehabilitation va sa višom stopom frakture osnove (osim kod osnove od cirkonijuma-oksida) 9 .
The data favor the use of zirconium-oxide bases in the fabrication of metal free bridges.The second important technical complication observed in a five-year period with zirconiumoxide bridges has been the presence of limited or wide fractures of the ceramic material placed over the basis 10 .This can be explained by the need for improvement of the mechanical-phys ical properties of ceramic material and insuf ficiently strong bond of the base and ceramic layer 11,12 .

Conclusion
In this clinical case with abrasion we dem onstrated a combined treatment approach with the use of metal free restorations and standard metalceramic restorations in order to rees tablish the health, function, and esthetics.Us ing the restorations made of metal free ceramic based on zirconium (IPS e.max zirPress, Ivo clar Vivadent, Schaan, Liechtenstein), it is pos sible to achieve perfect clinical results in both frontal and in lateral segments.Moreover, the introduction of new composite cements (Multi link Automix, Ivoclar Vivadent, Schaan, Liech tenstein) has contributed to the achievement of predictable and stable bonding between the prepared tooth surface and ceramic restoration, and the need for surgical elongation of clinical crowns has been obviated.Since these modern metal free systems have been introduced only recently, there is a small number of longitudi nal studies, but further studies will give new information about the longevity of these dental constructions.

Slika 3 . 3 .
Model sa definitivnom preparacijom gornjih zuba Figure Model with final preparation of upper teeth

Slika 4 . 4 .
Model sa definitivnom preparacijom donjih zuba Figure Model with final preparation of lower teeth

Slika 6 . 6 .
Izgled substrukture prednjih i bočnih kruna Figure View of the substructures for the anterior and lateral crowns