sistemas ceramicos en prótesis fija unitaria

SISTEMAS CERÁMICOS EN PRÓTESIS FIJA UNITARIA

Roberto Cáceres | Felipe Opazo | Pablo Ríos | Cristian Rosas | Cristian Vera

Docente: Dr. Ricardo Neira

Universidad Austral de ChileEscuela de OdontologíaClínica Integral del Adulto I

OBJETIVO GENERAL

Describir y comparar los diferentes sistemas cerámicos utilizados en Prótesis Fija Unitaria

OBJETIVOS ESPECÍFICOS

- Describir la composición y manufactura de los sistemas cerámicos en PFU.

- Definir parámetros de comparación entre los diferentes sistemas cerámicos.

- Comparar los sistemas cerámicos en parámetros como: translucidez, resistencia, módulo de elasticidad, tratamiento de superficie y éxito en el tiempo.

- Determinar las indicaciones de los sistemas cerámicos

PREGUNTA CON ENFOQUE CLÍNICO

En base a parámetros comparativos ¿Qué sistema cerámico es más estético, más resistente y con mayor éxito en el tiempo?

Búsqueda de la información

1. Determinación de sistemas cerámicos a estudiar.

- Sistemas más utilizados en el mercado actual- Sistemas con más estudios clínicos.

IPS Empress ® (Ivoclar)IPS Empress 2 ® (Ivoclar)

Procera AllCeram ® (Nobel Biocare)In-Ceram ® (VITA)

Cercon Zirconia ® (Dentsply)

Búsqueda de la información

2. Búsqueda en bibliografía sobre materiales dentales y prótesis fija.

3. Búsqueda en PubMed, utilizando los términos:

- translucency AND all-ceramic AND crown

- resistance AND all-ceramic AND crown

- mechanical properties AND all-ceramic AND crown

- surface treatment AND all-ceramic AND crown

- clinical trials AND all-ceramic AND crown

PRÓTESIS FIJA UNITARIA

Coronas metal cerámicas

Coronas libres de metal

Propiedades mecánicas excelentes

Estética

CERÁMICAS DENTALES

Clasificación

Porcelanas convencionales Porcelanas modernas o vitrocerámicas

Porcelanas con buenas propiedades estéticas pero malas propiedades mecánicas

Porcelanas reforzadas con cristales con el objetivo de aumentar sus propiedades mecánicas.

CERÁMICAS DENTALES MODERNAS

Composición básica

% Feldespato

Fase vítrea Fase cristalina% Cristales de refuerzo

• Leucita• Disilicato de Litio• Óxido de aluminio• Óxido de magnesio• Óxido de zirconio

o Vitrocerámicas

Translucidez Resistencia

SISTEMAS CERÁMICOS EN PFU

1. IPS Empress ® (Ivoclar)2. IPS Empress 2 ® (Ivoclar)3. Procera AllCeram ® (Nobel Biocare)4. In-Ceram ® (Alumina, Spinell, Zirconia) (VITA)5. Cercon Zirconia ® (Dentsply)

SISTEMAS CERÁMICOS EN PFU

Núcleo

Porcelana de recubrimiento

Cerámica reforzada, altamente resistente

Porcelana con fase vítrea en alta cantidad

Sistema IPS Empress

Vitrocerámica suministrada en forma de lingotes enucleados, que son calentados a 1150ºC durante 45 minutos, y luego comprimidos, fluyendo dentro de un molde.

IPS Empress IPS Empress 2

Leucita Disilicato de litio40% 60%

Técnica de Laboratorio: Sustitución de cera perdida.

Sistema IPS Empress

Fuente: Invisible, Restauraciones estéticas cerámicas

Sistema In-CeramSe esparce una lechada sobre el muñón y se calienta en un horno a 1120ºC para la confección de cofia parcialmente sinterizada, la que luego es infiltrada con vidrio a 1400ºC durante 4 horas.

In-Ceram Alumina In-Ceram Spinell

óxido de aluminio.

In-Ceram Zirconia

99% 72% óxido de aluminio.

67%óxido de aluminio.

28% óxido de magnesio

33% zirconia

Técnica de Laboratorio: Condensación sobre muñón refractario

In-Ceram Alumina

Sistema In-Ceram (Vita)


Sistema Procera All-Ceram

Bloques prefabricados de cerámica con base de óxido de aluminio, son tallados en forma mecanizada sobre troquel de mayor tamaño (23%), se envía a horno a 500ºC para remover cofia del troquel, y finalmente a horno de 1640ºC para sinterización final con contracción.

óxido de aluminio.99%

Técnica de Laboratorio: Tecnología asistida por computador (CAD-CAM)

Sistema Procera All-Ceram


Sistema Cercon Zirconia

Utiliza un patrón de cera, y el sistema Cercon Brain. Se coloca el patrón a un lado y un bloque presinterizado a otro. El patrón es escaneado, y a su vez esa información es utilizaada para el tallado del bloque.

óxido de zirconio.95% 5%

óxido de itrio

Técnica de Laboratorio: Técnica asistida por computadora (Cercon Brain)

Parámetros de comparación

• Translucidez

• Resistencia a la fractura

• Módulo de elasticidad

• Tratamiento de superficie

• Éxito en el tiempo

Translucidez

IPS Empress Esthetic - Special Edition

ComplesTécnica 3D Complex

ConclusiónEn el pasado, los ceramistas estaban obligados a trabajar con técnicas muy complicadas para

obtener los resultados estéticos deseados. Actualmente, sin embargo, estos efectos se

pueden obtener de forma rápida y sencilla debido a las propiedades de las modernas

cerámicas. La óptica de las nuevas cerámicas, cuyo aspecto es más similar al diente natural,

nos permite olvidar las complicadas técnicas del pasado y sustituirlas por técnicas más

sencillas. Gracias a su estructura cristalina especial las masas de cerámica IPS Empress

Esthetic ofrecen al protésico la posibilidad de reproducir las propiedades ópticas de los

dientes naturales. Esto quiere decir que actualmente podemos obtener de forma elegante y

sencilla excelentes resultados estéticos.

Restauración terminada

10

Fuente: IPS Empress Esthetic Manual Guide

TranslucidezPropiedad física de la materia que permite el paso de la luz dispersando los rayos luminosos. La translucidez es considerada como la situación intermedia entre lo opaco y lo transparente (Bruguera, 2008)

Medición: se asigna valor 0 a un estado de transparencia, y un 1 a un estado de opacidad.

10

restorations in dentistry today.One of the most significant of these changes

occurred in 1983 when Horn5 and Simonsen andCalamia6,7 independently introduced acid-etchedceramics to create the bonded porcelain veneer,one of the most successful restorations whenbonded primarily to enamel. With the advent ofdentin adhesives in the early 1990s, porcelainrestorations with significantly higher bondstrengths than those that had been available pre-viously became possible.8,9 This prompted manypractitioners to forego metal-ceramics and usebonded ceramics in clinical situations in whichthey had never before been used—sometimes suc-cessfully and sometimes unsuccessfully. A chal-lenge still exists in that the dentin/adhesive bondis not as durable or predictable as the enamel/adhesive bond.10

Major strides in technology permitting routineuse of all-ceramic restorations are the improve-ment and scientific innovations in the ceramicmaterials themselves. High-strength corematerials containing alumina, zirconia, zirconia-toughened alumina, magnesium aluminate spineland lithium disilicate have been introduced andclinically tested. Laboratory technicians(ceramists) then apply esthetic veneeringceramics over these core materials to create afinal, esthetic restoration.

The other change that has occurred in the useof all-ceramic restorations has been societal atti-tudes concerning esthetics. Before the early1980s, people in the entertainment industry wereprimarily the only patients who requested elec-tive esthetic dental procedures. With the onlytreatment option being full-mouth rehabilitationinvolving the use of complete-coverage crown

preparations with sub-gingival margins, thesepatients were faced withthe potential risks ofrecession, exposure ofthe margin, discoloredgingivae and pulpalinvolvement. Theseclassic metal-ceramicrestorations requirednot only extensive toothreduction, but a highlyskilled master techni-cian to achieve excellentesthetics.

MATERIALS OPTIONS

Modern all-ceramic systems can be categorizedbroadly into two groups: those that are translu-cent and those that consist of an opaque, high-strength core onto which esthetic layeringceramic must be applied to achieve a naturalappearance (Figure 1). Examples of translucentmaterials are conventional sintered feldspathicporcelain fabricated on refractory dies or plat-inum foil, pressable ceramics (for example, IPSEmpress Esthetic, Ivoclar Vivadent, Amherst,N.Y.) and some of the in-office machinableceramics made via computer-aided design/computer-aided manufacturing (for example,Vitablocs Mark II, Vita Zahnfabrik, BadSäckingen, Germany). Examples of opaque lay-ered materials are nonmetallic restorations madewith alumina, zirconia or lithium disilicate usedas high-strength core materials (for example, IPSe.max, Ivoclar Vivadent; Procera, Nobel Biocare,Göteborg, Sweden; In-Ceram, Vita Zahnfabrik;Lava, 3M ESPE, St. Paul, Minn.; and Cercon,Dentsply Ceramco, York, Pa.).

Properties. As a general rule, the two groupsof all-ceramic systems have distinctly differentproperties in several areas. With regard to toothreduction, clinicians can use the translucentmaterials with more conservative tooth prepara-tions compared with the opaque, layered systems.Optically, the translucent materials usually aremore esthetic than the layered materials. Mosttranslucent restorations must be bonded toimprove their predictability, while layered resto-rations do not have this sensitivity to choice ofluting agent.11

Because of these differences, dentists can usemost opaque layered materials for traditional

20S JADA, Vol. 139 http://jada.ada.org September 2008

Figure 1. All-ceramic and metal-ceramic crowns. Translucent unlayered (left to right): Dicor (Dentsply,York, Pa.; no longer on the market), IPS Empress Esthetic (Ivoclar Vivadent, Amherst, N.Y.), OPC (Pen-tron Ceramics, Somerset, N.J.). Opaque layered: In-Ceram Alumina (Vita Zahnfabrik, Bad Säckingen,Germany), In-Ceram Spinel (Vita Zahnfabrik), Procera Zirconia (Nobel Biocare, Göteborg, Sweden).Metal-ceramic crown with porcelain labial margin and conventional metal-ceramic crown.

Copyright © 2008 American Dental Association. All rights reserved.

on August 15, 2009

jada.ada.orgD

ownloaded from

Sistemas cerámicos están entre 0,65 y 1,00

lated for the remaining specimens, minimal deviation inluminous reflectance was found between the 3 remain-ing specimens and the Empress 2 sample in the previouscore study.3 Comparison of the results was thereforepossible.

Contrast ratio variations after veneering and glazing re-sulted in 3 approximate groupings of decreasing translu-cency: (1) Empress, In-Ceram Spinell, Empress 2, andProcera; (2) In-Ceram Alumina; and (3) In-Ceram Zirco-nia and the metal-ceramic material (52 SF veneered withVita Omega porcelain). This variation may have been dueto differences in core crystal volume and the refractive in-dex. Reduced crystalline content and a crystal refractiveindex close to that of the matrix cause less scattering oflight.8 Compared to In-Ceram and Procera, Empress andEmpress 2 have a lower crystal content within the matrix.Leucite (used to strengthen Empress) and lithium disilicate(used to strengthen Empress 2) have refractive indices of

1.51 and 1.55,6 respectively—close to that of the porcelainmatrix of 1.50.5 In contrast, zirconium oxide has refractiveindex of 2.20, alumina of 1.76, and spinell of 1.72.7 Thethinner core of the In-Ceram specimens, however, com-pensated for the opacity caused by a greater difference inthe refractive index of the In-Ceram crystalline core to thematrix.

The controls used in this study allowed a tangiblecomparison of translucency. Although the glass disc wasthicker than any of the veneered specimens, it was still13 times more translucent (Table III). This result indi-cates that the ceramic materials tested are relativelyopaque. All-ceramic materials have been advocatedlargely on the basis of improved esthetics over metal-ceramic restorations. Interestingly, In-Ceram Zirconiaspecimens and the metal-ceramic negative control ex-hibited similar opacity. If examined clinically, some ofthe other systems might also be indistinguishable from

Fig. 2. Glazed, veneered specimens on black-and-white backing with reflected light.

Fig. 3. Glazed, veneered specimens on black-and-white backing with transmitted and reflected light.

THE JOURNAL OF PROSTHETIC DENTISTRY HEFFERNAN ET AL

14 VOLUME 88 NUMBER 1

Translucidez

residual investment material by ultrasonic immersion for10 minutes in Invex liquid, which contained !1% hy-drofluoric acid (Ivoclar Williams, Ivoclar North Amer-ica, Amherst, N.Y.). The formed reaction layer was re-moved with 50-!m aluminum oxide at 1 bar pressure.

In-Ceram slip for Alumina, Spinell, and Zirconiaspecimens was prepared and rapidly applied with a num-ber 1 sable brush into a vinyl polysiloxane (Reprosil)split putty matrix approximately 0.6 mm in height and13 mm in diameter. The matrix was seated on a flat,special plaster surface (Vita Zahnfabrik). A sintering fir-ing was performed according to the manufacturer’sguidelines. For In-Ceram Alumina, glass powder (A2)was mixed with distilled water and applied in a thicklayer on the surface of the sintered discs; glass infiltrationfiring then was performed. Excess glass was removedfrom the infiltrated discs with a sintered diamond wheel.Finer residues of glass were airborne particle–abradedwith 50-!m aluminum oxide at 3 bar pressure. After oneglass control firing, the specimens still exhibited surfaceglassy areas; the discs therefore were airborne particle–abraded again, and a further glass control firing wasperformed. In total, 3 glass control firings were requiredto remove all evidence of surface glass.

In-Ceram Spinell and Zirconia specimens wereformed in a similar manner in accordance with the man-ufacturer’s instructions. Two glass control firings wererequired to ensure the absence of glass residue for In-Ceram Spinell samples. In-Ceram Zirconia requiredonly 1 glass control firing. Procera AllCeram cores(0.8 mm in thickness) were supplied by the manufac-turer and reduced with a sintered diamond wheel to athickness of approximately 0.5 mm.

Vitadur Alpha dentin powder was mixed withbuild-up fluid (Vita Zahnfabrik). The dentin slurry washand-vibrated into a vinyl polysiloxane matrix (Reprosil,16 mm diameter and 0.8 mm height) on platinum foil.Vibration and absorption with a clean paper tissue were

used to remove excess moisture. The specimens werefired according to the manufacturer’s instructions.

The metal-ceramic specimen was fabricated from awax pattern with use of the vinyl polysiloxane matrixused for the Empress cores. The specimen was cast in52 SF gold-palladium alloy.

The ceramic specimens were finished flat on a grind-er/polisher with wet 120-, 240-, and 400-grit siliconecarbide paper. The metal-ceramic alloy was finished witha metal finishing bur. All specimens were air-particleabraded with 50-!m aluminum oxide at 3 bar to createa similar matte surface finish. The specimens were ultra-sonically cleaned in distilled water for 10 minutes beforebeing measured with a digital micrometer (MitutoyoManufacturing Company Ltd, Kawasaki, Japan). Eachspecimen was measured 3 times; the average of the mea-surements was recorded as the specimen thickness.

A quantitative measurement of translucency wasmade by comparing reflectance of light (ratio of theintensity of reflected radiant flux [light] to that of theincident radiant flux22) through the test specimen over abacking with a high reflectance to that of low reflectanceor high absorbance. This procedure produced a contrastratio (CR) in which CR " Yb/Yw: the reflectance oflight of the material on a black surface (Yb) to the re-flectance on a white surface (Yw) (Fig. 1). This ratiotends toward unity for opaque materials and towardzero for transparent materials.14

An integrating sphere (RSA-PE-20; Labsphere,North Sutton, N.H.) was attached to a calibrated spec-trophotometer (Lambda20; Perkin-Elmer Corp, Nor-walk, Conn.) for specimen measurement. A mask wasplaced to reduce the size of the measuring port from adiameter of 13 mm to 4.5 mm. The specimens weremeasured with 0-degree illumination and diffuse view-ing geometry. Data were measured with Perkin-Elmersoftware to calculate luminous reflectance with CIE il-luminant D65 and the 2-degree observer function. Each

Fig. 1. Measurement of contrast ratio. Opaque: same light is reflected independent of backing. Yb " Yw, contrast ratioYb/Yw " 1. Transparent: all light is absorbed with black backing. Yb " 0, contrast ratio Yb/Yw " 0.

THE JOURNAL OF PROSTHETIC DENTISTRY HEFFERNAN ET AL

6 VOLUME 88 NUMBER 1

Fuente: M. J. Heffernan, et al. (2002). `Relative translucency of six all-ceramic systems. Part I: core materials.'. The Journal of prosthetic dentistry 88(1):4-9.

Estudio / Material

IPS Empress

IPS Empress

IPS Empress 2

IPS Empress 2

In-Ceram Spinell

Procera All-Ceram

In-Ceram Zirconia

In-Ceram Alumina

Cercon Zirconio

Grosor 0,5 mm

0,8 mm

0,5 mm

0,8 mm 0,5 mm 0,5 mm 0,5 mm 0,5 mm 0,5 mm

Chen et al 0,78 - - - - - 1,00 0,94 1,00

Heffernan et al. 0,64 0,72 0,68 0,74 0,67 0,72 1,00 0,86 -

Translucidez

Más translucido Menos translucido

Translucidez

1. Composición del núcleo

Óxido de Aluminio no refleja la luz, por lo que la translucidez es inferior comparada con cristales de leucita o disilicato de litio.

Sistema Procera All-CeramCristales de óxido de aluminio Sistema IPS Empress

Cristales leucita

0,640,72

Translucidez


La espinela de óxido de magnesio presenta translucidez similar a un diente natural (Chen, 2008)

Sistema In-Ceram SpinellCristales de óxido de magnesio

0,67

Translucidez


Los sistemas basados en Zirconio son menos translucidos que los cristales de alumina, magnesio y feldespáticas (Heffernan, 2002)

Sistema In-Ceram ZirconiaCristales de Alumina y óxido de zirconio

Sistema Cercon ZirconiaCristales de óxido de zirconio

1,001,00

Translucidez

2. Efecto del grosor del material

Heffernan analizó un mismo material en diferentes grosores de núcleo, resultando diferencias significativas de translucidez.

IPS Empress 0,5 mm IPS Empress 0,8 mm

0,64 0,72IPS Empress 2 0,5 mm IPS Empress 2 0,8 mm

0,68 0,74Mientras mayor grosor, menor translucidez“ ”

Translucidez3. Efecto del bizcochado

La opacidad se incrementa después del bizcochado.Razones: - Incremento en grosor- Interfase núcleo y porcelana de recubrimiento- Porosidad de las capas- Ciclo de cocción

4. Efecto del glaseado

En los estudios de Heffernan y Chen, se demostró que el glaseado disminuye levemente la translucidez.

Translucidez

Sistema In-Ceram SpinellCristales de óxido de magnesio

Sistema IPS EmpressCristales leucita o disilicato de litio

Alta translucidez

Sistema IPS Empress 2Cristales de óxido de magnesio

0,640,67 0,68

Grosor: 0,5 mm

Translucidez

Moderada translucidez

Sistema Procera All-CeramCristales de óxido de aluminio

0,72

Grosor: 0,5 mm

Translucidez

Baja translucidez

Sistema Cercon ZirconiaCristales de óxido de zirconio

Sistema In-Ceram ZirconiaCristales de Alumina y óxido de zirconio

Sistema In-Ceram AluminaCristales de óxido de magnesio

Grosor: 0,5 mm

1,00

0,861,00

Resistencia flexural biaxial

3

IPS Empress Esthetic


Fuerza flexural (compresiva y traccional) máxima que soporta un material sin sufrir fractura.

Medición: Se realiza una fuerza flexural en cierta unidad de espacio, por lo que se mide en unidades de presión (MPa). Prueba de resistencia consiste en una barra sujeta a ambos lados, sometido a una carga estática.


Análisis de estudiosSistema

cerámicoAlbakry (2003)

Chen (2008)

Wagner (1996)

Yilmaz (2007)

Guazzato (2002)

Tinschert (2000)

Rizkalla (2004)

Ban (2008)

IPS Empress 175 - 132 101,18 - 83,9 120 -

IPS Empress 2 407 355 - - - - 400 400

Procera - - 687 - - - - 472In-Ceram Spinell 352 - - - - 400

In-Ceram Alumina - 514 - 341,80 600 429,3 475 500

In-Ceram Zirconia - 592 - 541,80 620 - - 600

Cercon Zirconia - 910,5 - 1140,80 - 913 - 1200


Clínicamente hay gran variación en los parámetros de diseño y realización, por lo que los estudios sólo son una referencia.

Limitaciones del análisis

Los factores que contribuyen a aumentar la resistencia no dependen exclusivamente de la composición de las porcelanas.


Todos los sistemas analizados poseen adecuada resistencia a la fractura, porque todos superan el valor límite de 100 MPa (ISO 6872). Todos pueden ser utilizados en zonas anteriores y posteriores.

Algunos sistemas convencionales como porcelanas feldespáticas, el valor esta muy por debajo de los 100 MPa, por lo que se contraindicarían en zonas posteriores.


Cercon Zirconia e In-Ceram Zirconia en todos los estudios demuestran ser los más resistentes a la flexión.

Conclusiones

Transformación resistente

En zonas con alto estrés mecánico (como punta de una grieta) sufre transformación de fase cristalina, pasando de tetragonal a monocíclica, adquiriendo mayor volumen, aumentando la resistencia y evitando la propagación de la fractura.


En base a los estudios analizados, podemos agrupar los sistemas cerámicos según resistencia en:

Sistemas con alta resistencia

Sistemas con moderada resistencia

Sistemas con baja resistencia

Cercon ZirconiaIn-Ceram Zirconia

IPS EmpressIPS Empress 2

In-Ceram AluminaProcera

In-Ceram Spinell

Porcelanas feldespáticas

<100 MPa100 - 500 MPa>500 MPa

Módulo deelasticidad

Módulo de elasticidad

Comportamiento elástico de un material, según la dirección donde se aplica una fuerza. Representa la rigidez de un material

Medición: GPa


Análisis de estudios

Sistema cerámico Albakry (2002) Ban (2007) White (2005)

IPS Empress 65 GPa 92 GPa 71 GPa

IPS Empress 2 103 GPa - -

Procera - 420 GPa -

In-Ceram Spinell - 185 GPa -In-Ceram Alumina - 280 GPa -

In-Ceram Zirconia - 258 GPa -

Cercon Zirconia - 210 GPa 224 GPa


Relación % de relleno / Módulo de elasticidad

IPS Empress. 40% 65 GPa

IPS Empress 2 60% 103 GPa

In-Ceram Spinell 72% 185 GPa

Procera AllCeram 99% 420 GPa


IPS Empress corresponde al sistema menos rígido debido a que tiene menor cantidad de fase cristalina (40% leucita), siendo menos rígido y menos resistente.

Por otro lado, Procera tiene el más alto módulo de elasticidad, lo que se explica por su alto contenido de fase cristalina (99% óxido de aluminio).

Conclusiones


En base a los estudios analizados, podemos agrupar los sistemas cerámicos según módulo de elasticidad en:

Sistemas con alto módulo de elasticidad

Sistemas con moderado módulo

de elasticidad

Sistemas con bajo módulo de

elasticidad

Procera All-Ceram In-Ceram AluminaIn-Ceram ZirconiaIn-Ceram SpinellCercon Zirconia

IPS EmpressIPS Empress 2

<150 MPa150 - 400 GPa>400 GPa

Tratamiento desuperficie

Tratamiento de superficie

La composición y microestructura de la superficie de las cerámicas tienen alta importancia en la adhesión.

El tratamiento de superficie, tiene como objetivo producir superficies irregulares necesarias para la adhesión micromecánica. (Torres, 2009)


Tratamientos de superficie existentes

• Grabado con ácido fluohidrico al 10%• Aire abrasivo con partículas de óxido de aluminio• Microarenado• Laser de CO2

¿Qué efecto tienen sobre los diferentes sistemas cerámicos?


Medición

Dos tipos de estudios:

1. Estudios que ven alteraciones microscópicas de morfología superficial luego del tratamiento de superficie.2. Estudios que evalúan resistencia adhesiva luego del tratamiento de superficie.


IPS Empress

Borges (2003), indicó que IPS Empress ve afectada su morfología de superficie al ser tratada con aire abrasivo.

Control (2000x) Abrasión con aire abrasivo (óxido de aluminio de 50 um

por 5 segundos)Fuente: G. A. A. Borges, et al. (2003). `Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.'. The Journal of prosthetic dentistry 89(5):479-488.


IPS Empress

Varios estudios demuestran que existe un gran incremento de la resistencia adhesiva al utilizar grabado ácido y aire abrasivo.

Control (2000x) Abrasión con aire abrasivo (óxido de aluminio de 50 um

por 5 segundos)Fuente: G. A. A. Borges, et al. (2003). `Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.'. The Journal of prosthetic dentistry 89(5):479-488.


IPS Empress 2En los estudios de Torres (2009) y Borges (2003) se determinó que grabado con acido fluorhidrico seguido de tratamiento con aire abrasivo genera microrugosidades favorables para la adhesión.

Control (2000x) Aire abrasivoGrabado ácido fluorhidrico 10% por

20 segundosFuente: G. A. A. Borges, et al. (2003). `Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.'. The Journal of prosthetic dentistry 89(5):479-488.


IPS Empress 2Grabado ácido y aire abrasivo dan como resultado los valores mas altos de resistencia adhesiva comparado al resto de los sistemas ceramicos.

Control (2000x) Aire abrasivoGrabado ácido fluorhidrico 10% por

20 segundosFuente: G. A. A. Borges, et al. (2003). `Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.'. The Journal of prosthetic dentistry 89(5):479-488.


Procera All-Ceram Borges (2002), concluyó que el aire abrasivo produce una superficie lisa. También demostró que el grabado con acido fluorhidrico no causa ningún efecto en este sistema.

Control Aire abrasivo

Fuente: G. A. A. Borges, et al. (2003). `Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.'. The Journal of prosthetic dentistry 89(5):479-488.

Grabado ácido fluorhídrico 10%


Procera All-Ceram En otros estudios, se demostró que ninguno de los tratamientos de superficie produce resistencias adhesivas mayores que una superficie no tratada.

Control Aire abrasivo


Grabado ácido fluorhídrico 10%


In-Ceram AluminaBorges y cols, concluyó que el aire abrasivo modifica levemente la morfología característica de este sistema. El grabado ácido no modifica la morfología.

Control Grabado con acido fluorhidrico 10% por 2

minutos

Aire abrasivo


for the clinical success of ceramic restorations. Adhesive resincements are recommended for all-ceramic restorations toensure clinical success.40 Resin bonding to In-Ceram ceramicscannot be achieved with the methods commonly used withconventional glass ceramics. Thus, the present study aimed toinvestigate the effects of SB with Al2O3, HFA etching, AB andCO2 laser irradiation on surface roughness and shear bondstrengths of IA, IS and IZ. Also, the relationship betweensurface roughness and bond strength was determined.

The null hypothesis was partially accepted, such that, CO2

laser treatment did not increase the surface roughness on anyceramic group, however, revealed increased bond strengthcompared with other treatments, especially on IZ.

The shear bond test is one of the most commonly usedbond strength tests.41–43 Shear stresses are believed to bemajor stresses involved in in vivo bonding failures ofrestorative materials.41,42 Clearly, differing methods of loadapplication lead to differing stress distributions. Thus, one

Fig. 3 – SEM photographs of In-Ceram Alumina surfaces of A, untreated; B, sandblasted; C, airborne particle abrasion; D,hydrofluoric acid etch; E, CO2 laser irradiation (original magnification 1000T).

Fig. 4 – SEM photographs of In-Ceram Spinell surfaces of A, untreated; B, sandblasted; C, airborne particle abrasion; D,hydrofluoric acid etch; E, CO2 laser irradiation (original magnification 1000T).

j o u r n a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 8 4 8 – 8 5 6 853
















In-Ceram AluminaPor otra parte, Ersu (2009) concluyó que si bien hay mínimas modifcaciones superficiales, la resistencia adhesiva no aumenta con aire abrasivo, microarenado ni grabado ácido.


Control Grabado con acido fluorhidrico 10% por 2

minutos

Aire abrasivo






















Tratamiento de superficieIn-Ceram SpinellErsu (2009), determinó que su estructura se ve levemente afectada por microarenado y aire abrasivo.















Microarenado Aire abrasivo








Grabado con ácidofluorhídrico al 10%








Control

Tratamiento de superficieIn-Ceram SpinellSin embargo, sólo se ve leve aumento de resistencia adhesiva con microarenado.















Microarenado Aire abrasivo
















Control

Tratamiento de superficieIn-Ceram ZirconiaTorres y cols, indican que este sistema ve levemente afectada su superficie con aire abrasivo y microarenado, y no se afecta con grabado ácido.

Control


must expect uneven stress distributions and acknowledgethat the bond strengths reported are nominal values and needcautious interpretation. The use of bond strength data basedon static load-to-failure tests should be restricted tocomparisons of relative effects ofmaterial properties,materialmicrostructure and treatment conditions that may enhancethe resistance to fracture.44 Hence, shear bond test wasused in the present study to evaluate the bond strength ofdentin to glass-infiltrated alumina-based ceramics withmodified surfaces.

A potential limitation to clinical use of IA and IS dentalceramics has been inability to etch fit surfaces.5,25 According

to the current study, all surface treatments created roughersurfaces compared with untreated ones, which reveals thatHFA has etched the glassy phases of In-Ceram ceramics. DellaBona et al.28 have reported that although there was not anydifference in surface roughness among untreated and HFAetched IZ, there is reduction in silicon [Si(K)] after HFAtreatment, supporting the assumption of the HFA action onthe glassymatrix. Wood et al.5 have recommended sandblast-ing as the most effective surface treatment for IA and ISceramics. In the present study, SBwith Al2O3 provides roughersurfaces on IS than on IA and IZ, which is in agreement with a

recent study.28 Hence it may be concluded that, SB is analternative conditioning procedure for improving surfaceroughness of IS.

In this study, although SB creates rougher surfaces, it doesnot enhance the bond strength. This may be due to the factthat SB creates surface irregularities without micromechani-cal retention.4,43 Wood et al.5 have reported that SB createdsurface irregularities without undercuts, therefore the bondstrength may be reduced after prolonged periods. Also inagreement with the present study results, Derand andDerand43 have found that SB and HFA did not influence shear

bond strength on zirconia ceramic. On the other hand,according to Della Bona et al.,25 SB revealed significantlyhigher bond strength values than HFA etching for IZ, which isincongruous with our results.

SEM analysis revealed that the surface treatments otherthan CO2 laser did not change the surface structure of anyceramic group. The shallow irregularities observed in thecontrol groups were also found after the treatments as alsostated by other studies.19 Glass-infiltrated alumina-basedceramics are infiltrated by lantanium–aluminum–silicateglass containing less than 5% of silica by weight. As the silicaphase is the only phase able to be etched by HFA, the etching

was therefore inefficient. There were shallow irregularitiescompared with the control groups of ceramic groups, whichmay be related to the high content of alumina present in theseceramics and the glass infiltrated into the framework. There-fore, Al2O3 crystals used for AB and SB might have a hardnesssimilar to that of the Al2O3 crystals present in the ceramicstructure, confirming previous studies.19,27

Different reasons for microcrack formation on ceramicsafter CO2 laser irradiation have been proposed. According toGroßmann et al.,45 during the heating of the ceramic surfacecaused by the absorption of the laser radiation, superficial

emission of ions, electrons, and atoms take place. Due to thecharacteristic photo-ionization caused by the radiation, aphysical plasma emerges. Its formation is accompanied bythe development of extremely high pressure and fluctuationsin temperature in the range 10,000–50,000 K. This may causeextreme physical stress in the rehardening ceramic surface.Furthermore, the formation of two different phases of theceramic within the fused zones, one with crystallinestructure and one with an amorphous structure, bothshowing different thermal expansion coefficients, seems tobe possible.46 When the rounded-off material starts hard-

Fig. 5 – SEM photographs of In-Ceram Zirconia surfaces of A, untreated; B, sandblasted; C, airborne particle abrasion; D,hydrofluoric acid etch; E, CO2 laser irradiation (original magnification 1000T).

j o u rn a l o f d e n t i s t r y 3 7 ( 2 0 0 9 ) 8 4 8 – 8 5 6854













Microarenado













Aire abrasivo















In-Ceram ZirconiaSin embargo, la resistencia adhesiva se ve levemente mayor sólo con el aire abrasivo.

Control


























Microarenado













Aire abrasivo















Cercon Zirconia

Torres indica que la resistencia adhesiva más alta fue cuando Cercon fue tratado con aire abrasivo.

Se determinó además que la superficie no se ve afectada por grabado con ácido fluorhidrico.

Éxito en el tiempo

PRACTICE

be cemented in place with an rmgi cement rather than a resin cement.

254 BRITISH DENTAL JOURNAL VOLUME 205 NO. 5 SEP 13 2008

preparation is generally more aggressive and into dentine (~1.2 mm labially and ~2 mm incisally). This also allows for adequate porcelain thickness to provide increased strength and to develop the necessary aesthetics (Figs 1-4). The con-cept of a dentine bonded crown has been discussed by Burke et al. as arguably an ideal restoration.30,31 It differs from that of a 360° porcelain veneer where the tooth is previously unrestored and all attempts are made to remain in enamel.

The equigingival margins allow for placement of rubber dam for opti-mal moisture control during the resin bonding procedure (Fig. 5). Bonding to the marginal enamel provides a good seal that protects the more vulnerable underlying resin-dentine bond against degradation through water exposure.32

An indiscernible equigingival margin can then be obtained by use of trans-lucent marginal porcelain together with a translucent resin cement thereby tak-ing advantage of the ‘contact lens effect’ as described by Materdomini et al. (Fig. 6).33 Such invisible equigingival margins are not possible with alumina or zirconia based systems because of their increased opacity which requires their margins to be hidden subgingivally.

Another advantage of this type of ‘invisible margin crown’ is that future gingival recession will not cause unsightly exposure of crown margins.

In summary, the requirements for the optimal resin bonded anterior crown are:

• A good underlying substrate colour • Tooth preparation margins on enamel

for predictable resin bonding • Ability to place rubber dam for opti-

mal moisture control during bonding • A glass based all-ceramic system for

optimal translucency • A resin cement for optimal strength

and adhesion/sealing.

DISCUSSION Modern dentistry has seen the develop-ment of many new materials and tech-niques. Two major developments in recent times are dentine bonding and stronger all-ceramic crown systems. These tech-nologies are still relatively new and there-fore have not stood the test of time; good unequivocal scientific evidence is sparse. The dentist is left with the uneasy predic-ament of trying to base clinical decisions on scientific research yet still be able to offer his or her patients the latest materi-als and techniques. The key to the decision making process is a good understanding of the limitations and clinical indications of these newer materials as well as use of the correct techniques. Dentists should also keep basic biomechanical princi-ples in mind and be wary of informa-tion put out by companies with a vested commercial infl uence.

SUMMARY • Crowns on tooth preparations with

margins beyond the CEJ and with adequate resistance form should

This then necessitates the use of a high strength, Al or Zi based ceramic system

• Crowns on tooth preparations with margins beyond the CEJ and with inadequate resistance form should be cemented in place with resin cements. Resin cements allow for either a low strength, glass based or high strength Al or Zi based system to be used assuming the underlying substrate is not too dark. Note that this is an una-voidable compromise because in order to achieve adequate retention, a resin cement needs to be used despite the fact that the margins are on dentine or cementum

• Crowns on tooth preparation with equigingival margins in enamel and good underlying substrate colour should be made from a translucent, glass based ceramic system. These will require cementation with a resin cement under rubber dam

• Crowns on a dark underlying tooth substrate need to be made from a high strength and opaque Al or Zi based ceramic system. For aesthetic reasons, the margins should be extended slightly subgingival beyond the CEJ. This will then necessitate cementation with an rmgi.

With thanks to Dennis Mostert of Ceramiart, London for the excellent technical work.

1. Douglas R D, Przybylska M. Predicting porcelain thickness required for dental shade matches. J Prosthet Dent 1999; 82: 143-149.

2. Andersson M, Carlsson L, Persson M, Bergman B. Accuracy of machine milling and spark erosion with a CAD/CAM system. J Prosthet Dent 1996; 76: 187-193.

3. Conrad H J, Seong W J, Pesun IJ. Current ceramic materials and systems with clinical recommenda-tions: a systematic review. J Prosthet Dent 2007; 98: 389-404.

4. Raigrodski A J. All-ceramic full-coverage restora-tions: concepts and guidelines for material selec-tion. Pract Proced Aesthet Dent 2005; 17: 249-256.

5. Marquardt P, Strub J R. Survival rates of IPS empress 2 all-ceramic crowns and fixed partial dentures: results of a 5-year prospective clinical study. Quintessence Int 2006; 37: 253-259.

6. Fradeani M, Redemagni M. An 11-year clinical evaluation of leucite-reinforced glass-ceramic crowns: a retrospective study. Quintessence Int 2002; 33: 503-510.

7. Odman P, Andersson B. Procera AllCeram crowns followed for 5 to 10.5 years: a prospective clinical study. Int J Prosthodont 2001; 14: 504-509.

8. Fradeani M, D’Amelio M, Redemagni M, Corrado M. Five-year follow-up with Procera all-ceramic crowns. Quintessence Int 2005; 36: 105-113.

9. Heffernan M J, Aquilino S A, Diaz-Arnold A M,

Fig. 6 Final restoration after six months showing excellent cervical aesthetics with invisible equigingival margins

Éxito en el tiempo

En base a estudios prospectivos de entre 2 a 10 años, establece el porcentaje de éxito o rango de supervivencia.

Medición: Rango de supervivencia de Kaplan-Meier.

Parámetro de gran relevancia. Si bien existe muchos métodos de evaluación in-vitro de los sistemas cerámicos, este es el único parámetro que evalúa los sistemas integrando todos los parámetros de éxito.

Éxito en el tiempo


Sistema cerámico

Años de seguimiento

Indice de supervivencia

promedio


dientes anteriores


dientes posteriores

Oden (1998) 5 años 97% - -

Fradeani (2005) 5 años 96,7% 100% 95,15%

Walter (2006) 6 años 94,3% 96,7% 91,3%

Zitzmann (2007) 7 años - 100% 98,8%

Odman (2001) 10,5 años 97,7% - -

Denissen (2002) 4 años 100% - -

1. Sistema Procera All-Ceram

Éxito en el tiempo


2. Sistema IPS Empress

Estudio Años de seguimiento


promedio


dientes anteriores


dientes posteriores

Sorensen (1988) 3 años 98,7% - -

El-Mowaty (2002) - 92-99% - -

Fradeani (2003) 11 años 95,2% - -

Éxito en el tiempo


3. Sistema IPS Empress 2



promedio


dientes anteriores


dientes posteriores

Toskavul (2007)

1 año 4 meses 96,7% - -

Valenti (2009) 10 años 95,5% - -

Marquardt (2006) 5 años 100% - -

Éxito en el tiempo


4. Sistema In-Ceram (Alumina, Spinell y Zirconia)



promedio


dientes anteriores


dientes posteriores

Wassermann (2006) 5 años 91,7 - 100% - -

Bindl (2002) 5 años 92% - -

Huls (1995) 6 años 98% - -

McLaren (2000) 4 años 96% - -

Prubster (1997) 6 años 97,2% - -

Scotti (1995) 4 años 98,4% - -

Segal (2001) 6 años 99,1% - -

Sorensen (1992) 5 años 100% - -

Éxito en el tiempo

Los estudios utilizan diferentes muestras e intervalos de tiempo, sin embargo podemos evaluar las tendencias existentes sobre el éxito en el tiempo de cada uno.

Éxito en el tiempo

Todos los sistemas tienen indices de supervivencia muy altos, y no existe diferencias estadísticamente significativas entre uno y otro.

Los resultados son excelentes a mediano plazo, comparables con las coronas metal-ceramicas.

Deben realizarse más estudios para evaluar rendimiento clínico a largo plazo, e idealmente que todos los estudios diferencien el índice de supervivencia de las coronas en piezas anteriores y posteriores.

CONCLUSIONES

Desde el punto de vista de la translucidez:

Existe influyencia de la composición del núcleo cerámico: los más translucidos son leucita, disilicato de litio y oxido de magnesio.

Mientras más grosor, disminuye la translucidez.

El bizcochado y el glaseado, al ir incorporando más capas de porcelana, van disminuyendo la translucidez.

La translucidez es inversamente proporcional a la resistencia.

Los sistemas basados en Zirconio son los que presentan menor translucidez, por tanto menor estética. No se recomiendan en zonas anteriores.

CONCLUSIONES

Desde el punto de vista de la resistencia

No sólo depende de las propiedades del material, sino de múltiples factores dependientes del paciente y el operador.

Todos los sistemas actuales (porcelanas reforzadas) pueden ser utilizados en dientes anteriores y posteriores, ya que superan los 100 MPa.

Los sistemas basados en Zirconio son los más resistentes, superando ampliamente al resto de los sistemas.

En núcleos de menor resistencia, el esfuerzo lo recibe la porcelana de recubrimiento, lo que es desfavorable para la supervivencia de la corona.

CONCLUSIONESDesde el punto de vista del módulo de elasticidad:

Depende del porcentaje de cristales que refuerzan el material, por lo que los sistemas con mayor cantidad de refuerzo, poseen mayor módulo de elasticidad. Por tanto, Procera al tener 99% de cristales de refuerzo, es el más rígido.

Desde el punto de vista del tratamiento de superficie:

- Grabado con ácido y uso de aire abrasivo tiene el mayor efecto en IPS Empress e IPS Empress 2. El resto de los sistemas sólo ve levemente aumentada la resistencia adhesiva con tratamientos de superficie.

- Cercon de Zirconia e In-Ceram Zirconia no se ven afectados por los tratamientos de superficie.

CONCLUSIONES

Desde el punto de vista de éxito en el tiempo:

Todos los sistemas tienen índices de supervivencia aceptables y no existen diferencias estadísticamente significativas entre uno y otro.

No existe un sistema cerámico aplicable a todos los casos. La elección de un sistema u otro se basa en la necesidad. En la actualidad no existe un material superior en todos los aspectos evaluados en esta revisión.

REFERENCIAS BIBLIOGRÁFICAS1. M. J. Heffernan, et al. (2002). `Relative translucency of six all-ceramic systems. Part I: core materials.'. The Journal of prosthetic dentistry 88(1):4-9.

2. Y.-M. M. Chen, et al. (2008). `Translucency and biaxial flexural strength of four ceramic core materials.'. Dental materials : official publication of the Academy of Dental Materials 24(11):1506-1511.

3. M. Albakry, et al. (2003). `Biaxial flexural strength, elastic moduli, and x-ray diffraction characterization of three pressable all-ceramic materials.'. The Journal of prosthetic dentistry 89(4):374-380.

4. W. C. Wagner & T. M. Chu (1996). `Biaxial flexural strength and indentation fracture toughness of three new dental core ceramics.'. The Journal of prosthetic dentistry 76(2):140-144.

5. H. Yilmaz, et al. (2007). `Flexural strength and fracture toughness of dental core ceramics.'. The Journal of prosthetic dentistry 98(2):120-128.

6. M. Guazzato, et al. (2002). `Mechanical properties of In-Ceram Alumina and In-Ceram Zirconia.'. The International journal of prosthodontics 15(4):339-346.

7. J. Tinschert, et al. (2000). `Structural reliability of alumina-, feldspar-, leucite-, mica- and zirconia-based ceramics.'. Journal of dentistry 28(7):529-535.

8. A. S. Rizkalla & D. W. Jones (2004). `Mechanical properties of commercial high strength ceramic core materials.'. Dental materials : official publication of the Academy of Dental Materials 20(2):207-212.

9. S. Ban (2008). `Reliability and properties of core materials for all-ceramic dental restorations'. Japanese Dental Science Review 44(1):3-21.

10. S. N. White, et al. (2005). `Flexural strength of a layered zirconia and porcelain dental all-ceramic system.'. The Journal of prosthetic dentistry 94(2):125-131.

11. S. M. Torres, et al. (2009). `The effect of surface treatments on the micro-shear bond strength of a resin luting agent and four all-ceramic systems.'. Operative dentistry 34(4):399-407.

12. G. A. A. Borges, et al. (2003). Èffect of etching and airborne particle abrasion on the microstructure of different dental ceramics.'. The Journal of prosthetic dentistry 89(5):479-488.

13. A. Odén, et al. (1998). `Five-year clinical evaluation of Procera AllCeram crowns.'. The Journal of prosthetic dentistry 80(4):450-456.

14. M. Fradeani, et al. (2005). `Five-year follow-up with Procera all-ceramic crowns.'. Quintessence international (Berlin, Germany : 1985) 36(2):105-113.

15. M. H. Walter, et al. (2006). `Six-year clinical performance of all-ceramic crowns with alumina cores.'. The International journal of prosthodontics 19(2):162-163.

16. J . A. Sorensen, et al. (1998). ÌPS Empress crown system: three-year clinical trial results.'. Journal of the California Dental Association 26(2):130-136.

17. O. El-Mowafy & J.-F. F. Brochu (2002). `Longevity and clinical performance of IPS-Empress ceramic restorations-a literature review.'. Journal (Canadian Dental Association) 68(4):233-237.

18. S. Toksavul & M. Toman (2007). À short-term clinical evaluation of IPS Empress 2 crowns.'. The International journal of prosthodontics 20(2):168-172.

19. M. Valenti & A. Valenti (2009). `Retrospective survival analysis of 261 lithium disilicate crowns in a private general practice.'. Quintessence international (Berlin, Germany : 1985) 40(7):573-579.

20. A. Wassermann, et al. (2006). `Clinical long-term results of VITA In-Ceram Classic crowns and fixed partial dentures: A systematic literature review.'. The International journal of prosthodontics 19(4):355-363.

sistemas ceramicos en prótesis fija unitaria

Documents