Dental News - Cementation of restorations: A new luting composite

Stephanie Huth, DDS

Tue. 19 January 2016

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Variolink Esthetic (Ivoclar Vivadent), the light- and dual-curing luting composite, allows the dental professional to adhesively cement highly esthetic ceramic and composite restorations thanks to its flexible and well-structured Effect shade concept. Pre-polymerized excess material can be easily and efficiently removed.

Cementation materials establish a durable bond between the tooth structure and the restorative material and, therefore, contribute significantly to the long-term success of indirect restorations. Cementation materials are classified into three different types: conventional luting cements, self-adhesive and adhesive resin cements.

The advantage of conventional cements (e.g. zinc phosphate or glass ionomer cements) lies in the ease of use and more forgiving properties in adverse clinical conditions, such as excessive saliva or bleeding. However, these luting cements adhere mechanically to the tooth structure, hence retentive tooth preparation is required, and esthetically they are easily discernible because of the opaque shade.

The advent of adhesive resin cements has contributed to the rising importance of innovative restorative materials. Adhesive resin cements bond chemically with highly esthetic all-ceramics restorations, such as IPS e.max Press/CAD (Ivoclar Vivadent), and hence can be used even if no retentive preparation has been performed.

It is essential in such cases, however, that a luting material of an appropriate shade and translucency level is selected in order to obtain excellent esthetic results. This applies in particular to restorations with a low material thickness.

An additional advantage of adhesive luting composites over conventional cements represents the enhanced long-term integrity of the restoration margin. The low solubility and high resistance to wear of these luting composites lead to a reduced washing out of the cement gap.

Adhesive resin cements use adhesive to ensure a reliable bond to the tooth structure. The adhesive penetrates into the dentin tubuli and forms a hybrid layer by bonding to collagen fibres. Etching of the tooth structure removes the smear layer and exposes the dentin tubuli, resulting in an increased micro-retention.

The luting composite forms a chemical bond with the hybrid layer and, therefore, adheres well to dentin and enamel. Although the pre-treatment time of well-established self-adhesive composite cements is considerably reduced as no conditioning is required, they demonstrate lower bond strength values.

The high strength of IPS e.max lithium disilicate (Ivoclar Vivadent) allows clinicians to choose conventional, adhesive or self-adhesive composite cement for cementation. However, because of lower bond strength, it is recommended that self-adhesive and conventional cements be utilized in clinical situations with retentive prep design (less than 8 degree taper and minimum 4 mm height), adequate thickness (greater than 1 mm for anterior and 1.5 mm for posterior) and tight fit.

Although adhesive cements (e.g., Variolink Esthetic) are also indicated for these conditions, adhesive cements compliment IPS e.max lithium disilicate’s high strength in a variety of additional indications, including all types of restorations, any preparation design and any thickness of restorations. With no minimum requirements for adhesive cementation, adhesive cementation provides higher immediate bond strengths and a better marginal seal with IPS e.max restorations.

Optimum esthetics for a broad range of indications

Variolink Esthetic is a light- and dual-curing luting composite for the permanent cementation of ceramic and composite restorations. The light-curing version (Variolink Esthetic LC) is suitable for high translucent restorations where a longer working time is desired. This allows the dental professional to position, secure and subsequently light-cure all-ceramic veneers without any time constraints.

The dual-curing version (Variolink Esthetic DC) is suitable for ceramic and composite restorations for which a complete polymerization with light cannot be ensured because of the material’s opacity or strong wall thickness. In such cases, complete polymerization of the luting composite is achieved by the material’s combination of light- and self-curing properties, resulting in a reliable adhesion of the restoration.

Variolink Esthetic is available in five different shades. Variolink Esthetic Neutral, which features the highest level of translucency, does not affect the brightness value of the restoration and is color neutral.

“Warm” and “Warm+” increase the chroma of the restoration and, therefore, result in a gradual darkening of the overlying ceramic and composite restoration. The shades “Light” and “Light+” have a gradual brightening effect on the restoration. Utilizing the Variolink Esthetic Try-In pastes ensure that the ideal shade is selected to flow seamlessly with the adjacent dentition.

Easy excess removal

In the past, the time-consuming removal of excess luting cements before and after polymerization represented a disadvantage of the adhesive cementation technique. Variolink Esthetic has been further developed and sets a new standard for easy removal of excess material, making esthetic cementation simple. Excess material can be easily removed while still in a gel-like consistency because of the material’s optional pre-polymerization feature.

For the pre-polymerization, Variolink Esthetic DC is light-cured using the quarter technique, i.e., each quarter surface (mesio-oral, disto-oral, mesio-buccal, disto-buccal) is polymerized with light for two seconds. In case of Variolink Esthetic LC, the entire cement gap is pre-polymerized for two seconds (circular technique).

Controlled viscosity

The consistency of Variolink Esthetic has been optimally adapted to the requirements of dental practitioners. It has a convenient level of flowability and can be effortlessly and precisely extruded from the syringe. Furthermore, excess material smoothly flows from the cement gap but remains stable at the cementation joint so that it can be readily removed after successful pre-polymerization.

Combination with Adhese Universal

The adhesive material Adhese Universal (Ivoclar Vivadent) ideally complements Variolink Esthetic. The optional etching step with phosphoric acid is part of the “selective-etch” and the “etch and rinse” technique and results in an enhanced adhesion to enamel and optimized marginal seal. Adhese Universal is applied onto the tooth surface to be treated, starting with the enamel margins, and agitated for at least 20 seconds.

Subsequently, the adhesive is dispersed with oil- and water-free air until a glossy, stable film results. Because of the adhesive’s adapted thixotropy, the film thickness is kept to a minimum so the fit of the restoration is not affected. The material is polymerized with a light intensity of ≥ 500 mW/cm2 for 10 seconds before the placement of the indirect restoration.

Clinical case

A 25-year-old patient presented to our practice with a compromised resin composite restoration and secondary caries on tooth# 19. Because of the defective area was very large, treatment with an IPS e.max CAD restoration was decided in order to achieve an efficient and esthetic result.

After placement of the core build-up and preparation of the tooth, the tooth was scanned intraorally and a partial crown was designed.

Subsequently, the non-crystallized restoration in blue stage was tried in in the patient’s mouth to check the contact points and the fit of the restoration.
In order to assess the esthetic appearance and the shade effect, the characterized and fired restoration was again tried in using Variolink Esthetic Try-In Paste Neutral.

During these trial placements, care was taken that the tooth was sufficiently moist to ensure a lifelike shade impression. An anatomically shaped rubber dam (OptraDam Plus) was used for absolute isolation during the final placement of the restoration.

First, the enamel was etched for 15 seconds, followed by the entire cavity for another 15 seconds. Then, Adhese Universal was scrubbed onto the prepared tooth surface for 20 seconds and dispersed with a stream of air. Special care was taken that no material pools formed at the cavity floor. Subsequently, the restoration was light-cured with a polymerization light (Bluephase Style) for 10 seconds.

To obtain an optimum bond, the IPS e.max CAD restoration was etched with hydrofluoric acid (IPS Ceramic Etch Gel) for 20 seconds and conditioned with Monobond Plus 60 seconds followed by air-drying. In a next step, Variolink Esthetic DC was applied on the restoration, which was subsequently positioned on the tooth. After pre-polymerization of the excess material using the quarter technique (two seconds per quarter surface), the gel-like excess material could be easily removed using a scaler. Glycerine gel (Liquid Strip) was applied to prevent the formation of an oxygen inhibition layer.

In a final step, each segment of the restoration was light-cured for 10 seconds, the composite gap was finished and polished (Astropol) and the occlusion was checked.

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