ADHESIVE CEMENTATION IN ANTERIORS
Cementation is a crucial step in the process of ensuring the retention, marginal seal and durability of indirect restorations. Cementing procedures are either adhesive or non-adhesive. Adhesive cementation involves the use of an agent to promote bonding of the restorative material to the substrate; it is a combination of adhesive chemical bonding and micro-mechanical interlocking. Non-adhesive cementation involves the use of a luting agent to fill the space between the restoration and the natural tooth and relies solely on micro-mechanical retention. The clinician must have a good understanding of metal alloys or ceramic type to determinate whether a restoration should be cemented adhesively or non-adhesively. Choosing and applying the appropriate surface treatment and cementation procedure will contribute to long-lasting restorations.
CEMENTATION OF GLASS CERAMICS RESTORATIONS
This ceramic is highly esthetic, biocompatible and resistant to abrasion and compressive forces. It must be cemented to the prepared tooth adhesively to increase the restoration’s resistance to fracture (4). Nonadhesive cementation is not indicated for feldspathic ceramic5. The clinician must condition the glass feldspathic ceramics before performing adhesive cementation. The clinicians etches the ceramic internal surface with a solution of hydrofluoric acid (HF) 5% for approximately two minutes (6), to increase surface area, micro-mechanical retention and to clean surface for adhesive cementation. Then the surface must be silanized (5-6). Adhesive cementation to enamel or dentine requires the use of an adhesive system, followed by application of a resin cement (7). Adhesive systems can be either self-etching or total etching (8). Resin cements can be cured via light, chemicals or a dual process combining the two. Light-polymerized resins are recommended when the ceramic is thin and fairy translucent (9). Dual-polymerized resin cements are indicated when the ceramic is too thick or too opaque to allow the light transmission (5).
Pre-operative image of a veneer case.
Ceramic veneers in try-in stage.
Etch and rinse steps under rubber dam isolation.
Cement in place before polymerization.
Before and after, look at the profile change.
Before and after, look at the profile change.
Before and after.
TIPS & TRICKS
To pierce the dam in a multiple way without getting it dirty, we can use one as a template, place it on the one we must use and pierce both.
You can also use a new product which already has the image of the areas that have to be pierced on it.
CEMENTATION OF METAL RESTORATIONS
The cementetion of metal or metal-ceramic restorations can be performed with conventional cements (zinc phosphate, glass ionomers, resin-modified glass ionomer) or with a chemical polymerization resin cement. In using chemical polymerization composite cements, base-metal alloys can increase adhesive bond to metal and metal-ceramic restorations due to the formation of a oxides layer capable of reacting with cement acid groups (1-2). Silanize the surfaces of silicate metal (Rocatec, 3M ESPE, St. Paul, Minnesota, USA; and Silicoater, Heraeus Kulzer, Hanau, Germany) can further improve the micromechanics interconnection and chemical covalent bonds (3). The adhesion that is reached is a micro-mechanical type and some surface treatment is generally required to increase the adhesive bond. However, the noble alloys offer a lower adhesion capacity compared to other materials, such as vile alloys.
It is often difficult to lute adhesive restorations with sub-gingival preparation. The real trouble is wetness. We must avoid bleeding, so we need healthy tissues before cementation. Then we need to always put a retraction cord.
CEMENTATION OF ALUMINUM OXIDE CERAMICS
Adhesives protocols applied with success to the silica-based ceramics cannot be used for the aluminum oxide ceramics, because the etching with HF acid does not appear to increase the retention of resin cements10. These ceramics can be cemented conventionally rather than adhesively. Long-term adhesion studies recommend blasting (with particles of Al2O3 from 30-50 µm at 2,8-3 atm) to roughen the surface for micromechanics adhesion (11-12). Coating the ceramic with tribochemical silica and the air abrading of intaglio surface, followed by application of 10-methacryloyloxydecyl dihydrogen phosphate before using resin cement (chemical or dual cured resin cement ), improve the bond to this type of ceramic (13-14).
CEMENTATION OF ZIRCONIA CERAMICS
Zirconium oxide ceramics are characterized by the absence of glass in their composition. These ceramics possess high toughness and strength. Polycrystalline ceramics most often are cemented conventionally but can benefit from adhesive cementation. The use of low-pressure air abrasion with aluminum oxide particles or tribochemical silica application followed by application of an adhesion-promoting agent increase the bond-strength of resin cements (chemical or dual cured resin cement)(15).
It is mandatory that the clinician achieve affective isolation to keep the field free of saliva and other contaminants when using adhesive cements (16). Field isolation in not required in the case of zinc-phosphate and glass-ionomer cementation, but it’s necessary the fluid and saliva control.
CEMENTATION OF COMPOSITES
The bond between composite restoration and resin cements is very high and allows to have good levels of adhesion. So we can reach a very good adhesion even with indirect restorations. To have it one of the most effective protocols is that one that provides sandblasting the inner surface of the restoration with aluminum oxide for about 10 seconds, silanization (possibly activation with hot air or in special ovens of the silane), drying, then the application of a layer of bonding resin and at the end the luting procedures with a resin material that could be a dual composite cement or composite photo polymerizable (generally pre-heated in a special oven)(17-18).
Even crowns can be luted under rubber dam isolation. Just use an Ivory clamp for anteriors (no. 9, 9T or 212). Check that you see the whole preparation margin.
TIP: sandblast dentin with glycine powder to polish it and to increase its adhesive capacity.
Composite anterior indirect restorations can be easily luted with light-curing composite, thanks to the physical properties of this material. Heat the composite to 55°C in a dedicated oven for 20 minutes.
Not to include air bubbles, we must push the restoration with delicate pressure and in just one move, until it’s completely seated.
TIP: Whenever possible, immediate dentin sealing (IDS) is a must! Whenever we can use a rubber dam, we have to do it. How? Well, with an etch and rinse system, or with an etch and dry one. Just respect the right protocols (See Part 1 of this series of articles)
TIP: We need to always sandblast the inner surface of composite restorations, and sometimes, we must use 50 micron aluminum oxide particles to sandblast the build-up as well. The older the composite, the more important it is to sandblast the substrate for adhesion.
TIP: Luting with adhesive systems needs low lights. An operative light which is too strong (even with the loupes) could start the conversion of our adhesives or cements jeopardizing adhesion.
We have to use dual cements when the restoration is not easily penetrable by the halogen light. Among the dual cements those who do not self-polymerize in less than 6 minutes are preferred: this in order to reduce any problems done from the shrinkage of composites.
We can use light-cured composites when the artifact is easily crossable by halogen light and it is of adequate thickness (over 7-800 micron).
In the end we could us flowable composites when the restoration is easily crossable by halogen light but is very thin (less than 7-800 micron)(19-20-21).
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18. D’Arcangelo C, Vanini L. Effect of three surface treatments on the adhesive properties of indirect composite restorations. J Adhes Dent. 2007 Jun;9(3):319-26.
19. Magne P. Composite resins and bonded porcelain: the postamalgam era? J Calif Dent Assoc. 2006 Feb; 34(2): 135-47.
20. Devoto W. Direct and Indirect Restorations in the Anterior Area: A Comparison Between the Procedures. QDT 2003: 127-138.
21. Magne P, Belser U. Bonded porcelain restorations. Quintessence Books,2002.
All of the research works and references are by Prof. Angelo Putignano, Prof. Giovanna Orsini and Dr. Walter Devoto.The clinical work from pictures 1 to 18 & pics 24,25,26,29,30,31 is by Dr. Giuseppe Marchetti, the clinical work in pics 19,20,21,22,23 is by Dr. Monaldo Saracinelli, the clinical work in pics 27-28 is by Dr. Jordi Manauta & Dr. Walter Devoto.The creation of this article is by Dr. Giuseppe Marchetti, Prof. Giovanna Orsini and Style Italiano.This a copyright of Style Italiano – www.styleitaliano.org