8 Bonding of Ceramic Restorations
8.4 Ceramic Conditioning
Chemical bonds between resin composite and glass-ceramics are achieved by means of coupling molecules, for example, silane. Silane bonds with silicates in the glass matrix of the ceramic material (inor
ganic substance) on the one side, and polymerizes with the organic matrix of the composite resin on the other.
In order to be chemically active, the silane molecules must be hydrolyzed to silanol. Distinctions are made between one and two
component systems. Single-component silanes, which are more fre
quently used in clinical practice, are already hydrolyzed. Their expira
tion date must be strictly observed as they become inactive with time.
(Please note, the fluid must be clear. Discard if cloudy).
In the case of glass-infiltrated ceramics, etching alone does not achieve sufficient surface roughening. Therefore these ceramics must be sandblasted (with 50 to 100 11m Al203 at 2.5 bar). Although ceramic conditioning does not increase bond strength, it does improve wetta
bility'4. Glass-infiltrated ceramics should be cemented with a phos
phate monomer-based cement (see Chapter 7.2.1).
Oxide ceramics contain few or no silicates, and they cannot be silanized in the same manner as glass-ceramics. New resin composite cements (e.g., Panavia 2 1 ) contain an adhesive phosphate monomer ( e.g.,MDP) that can bond to oxides, thus making it possible to achieve chemical bonding of oxide ceramics with or without the use of an adjunctive bonding agent. However, application of an adjunctive bonding agent does improve the long-term stability of bonding and, is therefore, recommended4• As with metals, the improved chemical bonding must be achieved either by means of silica coating (RocatecTM system, Minnesota, USA) and subsequent silanization or without silica coating using special adhesive silanes (with adhesive phosphate monomers).
8.5 Clinical Procedure
8.5 Clinical Procedures
8.5.1 Indications and Recommended Materials
Co.m:litionina B.ondiiJQ.
Gloss-ceramics Etching
9.5% hydrofluoric acid Silonizotion
Syntoc
IMonobond Sl
Gloss-infiltrated Sandblasting Cleorfil SE Bond 100 [J.m Al203, 2.5 bar lor ED Primerl cerom1cs
Oxide ceramics Sandblasting Cleorfil SE Bond
!alumino, zirconiol 100 p.m Al203, 2.5 bar lor ED Primer!
Silonizotion
ICiearfil Porcelain Activator!
8.5.2 Step-by-step Procedure
a. Glass-ceramics
The step-by-step procedure for adhesive bonding of anterior ceramic crowns (Creapress®) is described by way of example.
Fig 1 The preparation for vital tooth 1 1 is circular with o 1 mm wide shoulder and rounded edges, ensuring o minimum loss of tooth struc
ture. Because the stump shade is ideal, the tooth con be restored using o translucent gloss-ceramic. Adhesive bonding increases the fracture strength of ceramic restorations. For this reason, adhesive bonding
should performed with due diligence. A thin retraction cord INo.OOO.OOl should be placed before adhesive luting whenever possible.
Cement Vortolink II
Ponovio 21 Ponovio 21
1 01
Chapter 8 Bonding of Ceramic Restorations
Figs 2a to 2c The pressed and sin
tered dentin core of optimal color and translucency is veneered to match the optical charac
teristics of the adja
cent teeth. Anterior and posterior views of the crown.
Figs 3a and 3b The internal surface of the crown is etched with 9.5% hydrofluoric acid (for example Ultradent'-" Porcelain Etch, Utha, USA) for 60seconds. !NB: Gloves and protective glass must be worn!l. The hydrofluoric acid is then rinsed off with running water. To remove etching precipitates, the crown is ultrasonically cleaned in alcohol for 4 minutes. Alterna
tively, it can be etched again with a weaker acid !phosphoric acidl for 30seconds.
102
8.5 Clinical Procedure
Figs 4a and 4b Scanning electron micrograph and 3D views of on ideally etched (l minute I gloss-ceramic. Significant surface area enlargement and numerous tunnels are clearly visible.
Fig
5
The internal surface of the etched and cleaned crown should hove a matte appearance without white deposits to ensure that the roughened surface shown in Figures 4a and 4b can be optimally used for cementation.Fig 6 Silanization is then performed for example using Ultrodent® Silane or
Monobond S. !NB: Compatibility with the cement is The silanized crown should now completely free of contami
nants (moisture, alcohol, etc.l. Once the sol
vent has evaporated (after about l minute!, a bonding agent is applied to the internal surface of the crown, and the crown is stored in a dark place.
103
Chapter 8 Bonding of Ceramic Restorations
Figs 7 and 8 A dentin bonding agent ISyntac primer, adhesive and bonding agent, Con
necticut, USAI is applied to the prepared tooth according to the manufacturer's instruc
tions. The thin coat of bonding agent gives the conditioned stump a slightly glossy appear
ance.
Fig lOa Bose and catalyst paste of the
some shade !ideally transparent) are mixed at a ratio of l : 1 and applied to the crown with a brush.
104
Fig 9 Variolink II !lvoclar Vivadentl is sup
plied in two consistencies llow and high vis
cosity) and in four shades. To reduce the occurrence of microleakage, the more high
ly filled and more highly viscous types should be used whenever possible. Vori
olink II can be dual-cured I base + catalyst) or only light-cured I basel. When luting all
ceramic crowns with thick layers of ceramic material, the dual curing variant should be used in order to ensure complete curing of the cement in the deep layers. For optimal esthetics, the transparent cement should be used.
Fig lOb Scanning electron micrograph
showing the bond between the conditioned ceramic I top) and Variolink II lbottoml. The cement con to ins various fillers of different sizes !hybrid fillers!.
Fig 1 1 After correct placement of the
crown, excess cement is carefully removed with foam pellets and dental floss. Glycerin gel should be applied around the crown margins in order to prevent oxygen inhibi
tion (i.e., the absence of curing in the resin composite Ioyer exposed to oxygen I. Poly
merization is then initiated for l minute on the buccal, palatal, and incisal surfaces and also when the dual-curing variant is used. Although it tokes up to roughly
24 hours for the cement to cure in the deep
er ceramic layers, the excess cement is removed immediately.
8.5 Clinical Procedure
Figs 12 to 14 Hardened residual cement is carefully removed with on or scaler while gently manipulating the gingiva. The retraction cord is removed, which con bring out some additional cement residue. The margin of the crown is finally carefully finished (e.g., with o covosurfoce bevel!. Radiological control of residual cement is difficult due to its low radiopacity.
105
Chapter 8 Bonding of Ceramic Restorations
b. Oxide ceramics
This procedure is illustrated based on a case example (zirconia crown placement).
Fig 15 Clinical situation after the prepara
tion of a gold post-retained crown on tooth 11. As the old post could not be
removed without endangering the root I risk of fracture!, it was included in the prepara
tion. To achieve an esthetic restoration, the multi-shade stump had to be covered with an opaque coping. The use of a translucent glass-ceramic material was contraindicated because a thick layer of ceramic would
have been required for masking. As the patient wished, a non-metal restoration, zir
conia, was selected. The crown as well as the approximal and occlusal contacts were inspected for fit before cementation. The crown was then degreosed with alcohol.
Figs 16a and 16b Frontal and caudal views of the definitive zirconia crown.
1 06
Fig 17 Scanning electron micrograph
showing the sandblasted surface of the zir
conia ceramic. Sandblasting does not enlarge the bond surface area of zirconia ceramics os much os is does that of etched glass-ceramics.
Fig 18 Cleorfil SE Bond is a two-compo
nent bonding system that consists of a self
etching primer and on adhesive I bonding ogentl. Both components contain the adhe
sive phosphate monomers needed to
achieve chemical bonding to zirconia. The primer alone is sufficient for cementation of zirconia ceramics. It acts as a dentin condi
tioner and silane activator.
Fig 19 Before cementation, the zirconia ceramic is preconditioned with Clearfil
Porcelain Activator, a special silane that must be activated with Clearfil SE Bond primer before application. A mixing dish and a brush ore required.
Fig 21 One drop of porcelain activator is then added.
8.5 Clinical Procedure
Fig 20 First, one drop of bond primer is dis
pensed into a well of the mixing dish.
107
Chapter 8 Bonding of Ceramic Restorations
Fig 22 The two liquids form on emulsion
like liquid that must be mixed well with a brush.
Fig 24 The activated silane is applied to the inner surface of the crown and allowed to react for 5 seconds. The surplus is then
blown off with stream of compressed air.
Fig 23 The mixture should hove a hove a uniform color and consistency.
Fig 25 The internal surface of the crown now looks oily. Warning: the external sur
face of the crown moy also look oily and feel slippery.
Figs 26 and 27 Dentin conditioning: primer !ED Primer or Cleorfil) is dispensed into another well of the mixing troy and applied to the prepared tooth with a brush. Priming time: 90 seconds ED Primer/20 seconds Cleorfil SE. Conditioning with silane is recommended when cementing Iorge resin composite build ups.
108
8.5 Clinical Procedure
Figs 28a and 28b Ponovio 21 TC and Oxyguord; the pastes ore mixed at o ratio of 1 : 1
and applied to the crown with o brush.
Fig 29 Scanning electron micrograph showing the bond between zirconia !top}
and Ponovio lbottoml. The high content of Iorge filler particles in the cement is clearly discernable.
Fig 31 Oxyguard is applied around the crown margins and allowed to react for 7 minutes. This serves to block the supply of oxygen so that the cement curing process can begin. The Oxyguard is subsequently rinsed off with water, and all cement
residues are thoroughly removed with a scaler. Radiological control of fit is possible
because the cement is radiopaque.
Fig 30 After checking the crown for proper fit, excess cement is removed with foam pel
lets.
109
Chapter 8 Bonding of Ceramic Restorations
l l 0
References
l. Albert FE, EI-Mowafy OM. Marginal adaptation and micro leakage ofProcera AJ!Ceram crowns with four cements. lot J Prostbodont 2004;17(5):529-535.
2. Anusavice K. Phillips' Science of Dental Materials. Philadelphia:
Saunders, 2001 :45 I -486.
3. Bertschinger C, Paul SJ, Uithy H, Scharer P. Dual application of dentin bond
ing agents: Effect on bond strength. Am J Dent 1996;9(3):1 15-119.
4. Blatz MB, Sadan A, Martin J, Lang B. In vitro evaluation of shear bond
strengths of resin to densely sintered high-purity zirconium oxide ceramic after long-term storage and thermal cycling. J. Prosthet Dent 2004;91(4):356-362.
5. Buithieu H, Nathanson D. Effect of ionomer base on ceramic resistance to fracture. J Dent Res 1993;72:175; Abstract No. 90.
6. Burke FJ, Fleming GJ, Nathanson D, Marquis PM. Are adhesive technologies needed to support ceramics? An assessment of the current evidence. J Adhes Dent 2002;4(1):7-22.
7. EdelhoffD, Sorensen J. Light transmission through all-ceramic framework and cement combinations. J Dent Res 2002;8 I :Abstract-No I 779.
8. Ferrari M, Mannocci F, Mason PN, Kugel G. In vitro leakage of resin-bonded all-porcelain crowns. J Adhes Dent 1999; I (3):233-242.
9. Gu XH, Kem M. Marginal discrepancies and leakage of all-ceramic crowns:
Influence of luting agents and aging conditions. Int J Prostbodont 2003;
16(2): 109-116.
l 0. Heffeman MJ, Aquilino SA, Diaz-Amold AM, Haselton DR, Stanford CM, Vargas MA. Relative translucency of six all-ceramic systems. Part I: Core
materials. J Prosthet Dent 2002;88:4-9.
11. Jensen ME, Sheth JJ, Tolliver D. Etched-porcelain resin-bonded full-veneer crowns: In vitro fracture resistance. Compend Contin Educ Dent
1989; 10:336-347.
I 2. Junge T, Nicholls J, Phillips K, Libman W. Load fatigue of compromised teeth: A comparison of three luting cements. Tnt J Prosthodont 1998; 1 1 :558-564.
13. Kappert, H.F. (2003) Klinische Materialkunde fiir Zahniirzte, p. 359.
14. Kern M, Thompson VP. Bonding to glass infiltrated alumina ceramic: Adhe
sive methods and their durability. J Prosthet Dent 1995;73:240-249.
15. Magne P, Douglas \VH. Porcelain veneers: Dentin bonding optimization and biomimetic recovery of the crown. lnt J Prosthodont 1999;12(2): 111-121.
16. Malament KA, Socransk.)' SS. Survival of Dicor glass ceramic dental restora
tions over 16 years. Part Ill: Effect of luting agent and tooth or tooth-substitute core structure. J Prosthet Dent 200 1;86(5):51 1-519.
17. Marquis PM. The influence of cements on tbe mecbanical performance of den
tal ceramics. Tn: Proceedings of the 5th lntemational Symposium on Ceramics in Medicine. Bioceramics 1 992;5:3 17-324.
18. Paul SJ, Scharer P. The dual bonding technique: A modified method to
improve adhesive luting procedures. lnlJ Periodont Rest Dent 1997;17(6):
536-545.
19. Rosenstiel SF, Gupta PK, van der Sluys RA, Zimmerman MH. Strength of a dental glass-ceramic after surface coating. Dent Mater 1993;9( 4):274-279.
20. Sjogren G. Marginal and internal fit of four different types of ceramic inlays after luting. An in vitro study. Acta Odontol Scand 1995;53(1 ):24-28.
21. Strub JR, Beschnidt SM. Fracture strength of five different all-ceramic crown systems. Int J Prosthodont 1998; 1 1 :602-609.
22. Tay F, Frankenberger R, Krejci I, Bouillaguet S, Pashley D, Carvalho R, Lai C.
Single-bottle adhesives behave as pem1eable membranes after polymerization.
In vivo evidence. J Dent 2004;32(8):61 1-621.
23. Van Dijken JW, Hoglund-Aberg C, Olofsson AL. Fired ceramic inlays: A six
year follow-up. J Dent 1998;26(3):219-225.
24. White SN, Furuichi R, Kyomen SM. Microleakage through dentin after crown cementation. J Endod 1995;21( 1 ):9-12.
25. Williamson RT, Kovarik RE, Mitchell RJ. Effects of grinding, polishing and overglazing on the flexure strength of a high-leucite feldspatbic porcelain. Jut J
Prosthodont 1996;9( 1 ):30-37.
References
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1 1 3
Chapter 9 All-ceramic Imp/on/ Supported Restorations
1 1 4
9.1 Clinical Aspects a n d Indications
Natural-looking implant-supported restorations play a major role in the esthetic success of prosthodontic treatments in the anterior region.
Two factors crucial to esthetic success are:
• Soft-tissue morphology
• Fmm and esthetics of the restoration.
Prefabricated titanium abutments have several esthetic limitations:
• As their round shape does not correspond to the natural tooth anatomy, the correct contour (emergence profile) must be estab
lished by the crown, that is, by deep submucosal placement of the crown margms. .
• Because the straight shoulder of these standardized abutments does not follow the scalloped contour of the surrounding soft tis
sues, the removal of excess cement can be difficult.
• The gray metallic color of the abutments may show through the soft tissues, resulting in gray discoloration of the gingiva.
In order to resolve these problems, individualizable custom abutments made of alumina ceramics were developed in the early 1990s 7•8•9•
The few available studies on the performance of alumina ceramic abutments show that good long-term results are achieved when these abutments are placed in the anterior and premolar region. In one study, the clinical success rate for alumina ceramic implant abutments was 93% after 1 to 3 years of service2. In a second study, the 5-year success rate for all-ceramic fixed partial dentures supported by alumi
na ceramic abutments was 97.2%3. Abutment fracture was identified as the main cause of implant failure in both studies.
The introduction of zirconia abutments should reduce the risk of abutment fracture by virtue of their superior material properties. The in vitro fracture load of implant-supported all-ceramic crowns with zirconia abutments was found to be 700 N compared with only 280 N for those with alumina abutments 11•
Unfortunately, clinical data on zirconia abutments are still scarce.
In the only long-term study published to date, none of the zirconia abutments studied had fractured after 4 years of service in the ante1ior
or premolar region'. Based on the available evidence, one can at least conclude that the successful placement of ceramic abutments in the anterior and premolar region is possible.
9.2 Advantages of Cera m ic Abutments
• Ideal color
The white or dentin-like color of ceramic abutments is estheti
cally ideal for all-ceramic restorations
Gingival recession causes fewer esthetic problems.
• Customizability
The shape of the individualized custom abutment resembles that of a prepared tooth
As the emergence profile is determined by the abutment, the crown margins can be scalloped to conform to the architecture of the surrounding soft tissues.
Controlled removal of excess cement is possible.
Correction of implant angulation is possible with some restrictions (minimum layer thickness)
• The possibility of veneering allows for prosthetic flexibility
• The implant-abutment connection exhibits good accuracy of fit (due to industrial prefabrication)
• Radiopacity of the abutment permits radiographic monitoring.
9.3 Disadvantages
• Higher risk of fracture due to the material properties of ceramic materials (see Chapter 2)
• Minimum layer thicknesses must be observed
• The screw access hole limits customizability
• The abutment screw is a the weakest link in the system'0
• The dental laboratory procedures are teclmically demanding and time-consuming
• High cost.
9.3 Disadvantages
1 15