Material science advancements have enabled dental professionals
to design and fabricate highly customized restorations that
meet patients’ aesthetic and functional requirements. Such
advancements are especially helpful when replacing failing or defective
restorations. Especially with large defects in the molar region,
where direct restorative therapy reaches its limits, both anatomy
and aesthetics can be restored by all-ceramic restorations.
In the past, posterior restoration guidelines dictated that function
and strength be the most important characteristics of restorative
materials. Although all-ceramic systems were produced from
the late nineteenth century, their indications have been limited due
to their poor mechanical properties and the associated failure rates.
Therefore, cast gold or other porcelain-fused-to-metal (PFM)
restorations with a higher fracture toughness and flexural strength
were generally employed for posterior restorations, where respective
forces of mastication occur. With the introduction of all-ceramic
systems, which could be improved by structural reinforcement and
defect-minimizing production process, the range of indications
could be expanded. Another breakthrough was achieved by adhesive
cementation, thus increasing the mechanical strength and
improving the longevity of a ceramic.
However, development of new materials in recent years has
allowed clinicians a reprieve from deciding between function
and aesthetics. Materials such as lithium disilicate (IPS e.max,
Ivoclar Vivadent) and universal cementation systems (Multilink
Automix Next Generation, Ivoclar Vivadent) have expanded
opportunities for dental professionals to offer the highest quality
metal-free, durable and aesthetic restorations for all clinical
indications, regardless of their location in the mouth.
IPS e.max is a ceramic material composed primarily of finegrained
Lithium Disilicate Crystals (LDC) that are embedded in
a glassy matrix consisting of silica, potassium oxide, phosphorous
oxide, zirconia, zinc oxide, alumina, magnesium oxide, and
coloring components. The amount of 70 Vol-% needle-like
crystals in the matrix leads to a microstructure that effectively
controls the optical, physical and mechanical properties of the
material, allowing for an overall stable and strong structure. The
material itself is highly translucent due to its adjusted refractive
indices between glassy matrix and LDC, making it an optimal
choice for aesthetic restorations. However, the material’s monolithic
nature also results in an extremely durable restorative
option, boasting a flexural strength of 360-400 MPa, according
to the manufacturer. This unique combination of strength and
aesthetics indicates lithium disilicate for effective use for a wide variety of restorations, including anterior and posterior crowns,
inlays, onlays, veneers and implant restorations.
A Universal Cementation System
To maximize the potential of such capable materials as
lithium disilicate, an equally efficient bonding system can be
employed to guarantee clinical long-term success. Multiple steps
are typically required in the cementation process, such as pretreatment
of the ceramic and the prepared tooth surface, to
ensure that complete bonding is achieved. As such, an ideal
cementation system would address all of these needs, with all
system elements working seamlessly together to provide the
most efficient bonding mechanism.
Multilink Automix Next Generation (Ivoclar Vivadent) is
such a system, providing exceptional restorative bonding while
simultaneously enhancing aesthetics. The self-curing luting
composite with light-curing option is indicated for placing indirect
restorations fabricated from a variety of materials, including
silicate and oxide ceramics, composites and metals.
According to the manufacturer, the Multilink Automix system
achieves optimal bonding when used in conjunction with
lithium disilicate (IPS e.max) restorations.
The Multilink Automix System enables an efficient clinical
workflow. The pre-treatment of the tooth surface can be conducted
with the timesaving application of the mixed, self-etching
Multilink Primer A/B onto the entire bonding surface. In addition,
Multilink Automix is dispensed from the automix syringe,
and the desired amount can be directly applied to the restoration.
There is no need for the use of manual mixing or activating
capsules. Moreover, a constant mixing ration is guaranteed.
The enhanced cement formula also promotes easier cleanup;
the material can be light-cured in quarter segments (e.g., mesiooral,
disto-oral, mesio-buccal, disto-buccal) for one to three seconds
per quarter surface to achieve a gel-like consistency that
can be easily removed with a scaler. The light exposure interval
depends on the light intensity of the polymerization lamp, the
distance between optical conductor and excess cement, and the
number of cemented abutments.
Patients and dentists alike will also benefit from other recent
updates to the Multilink Automix Next Generation system.
Shading has been expanded to include a new shade, white, that
demonstrates a medium translucency and is excellently suited
for glass-ceramic restorations. Try-in pastes are also now available
for determining the appropriate shade of Multilink
Automix with respect to the restoration.
The following case demonstrates how the use of advanced
materials such as lithium disilicate and an advanced universal
cementation system enables clinicians to meet patient demands
for functional yet highly aesthetic restorations, regardless of the
location in the mouth.
A patient presented with a failing restoration in the posterior
region (Fig. 1). After discussing several restorative options with
the patient, it was ultimately decided that the treatment plan
would consist of an IPS e.max lithium disilicate inlay restoration,
cemented with Multilink Automix Next Generation.
Though the restoration was located in the posterior region, the
patient expressed a desire for a natural looking restoration, leading
to the selection of a pressed lithium disilicate restoration.
To facilitate the development and fabrication of the provisional
and final restorations, an impression was taken first. The
patient was then anesthetized with 3% mepivacaine and the tooth
prepared. After preparation was complete, final and opposing
impressions, shade photographs and a bite registration were taken
to provide the laboratory with necessary diagnostic information.
A bisacryl provisional restoration (Telio CAD, Ivoclar
Vivadent) was then fabricated and cemented with provisional
cement (Telio CS Link, Ivoclar Vivadent) to permit the patient
to function while the definitive restoration was designed and
fabricated (Fig. 2). The Telio CAD system was chosen for longterm
provisionalization due to the material’s high flexural
strength and high homogeneity.
Upon completion of the lithium disilicate restoration fabrication,
the patient returned to the practice for seating. The patient
was first anesthetized with 3% mepivacaine, and the provisional
restoration removed. The preparations were then cleaned (Fig. 3)
and thoroughly rinsed to remove any remaining cement (Fig. 4).
The final restorations had been prepared for try-in using
Multilink Automix Try-In Paste (Ivoclar Vivadent), and margins,
occlusal, proximal contacts, and shades were verified (Figs.
5, 6). Once approved by the patient and dentist, the restorations
were prepared for final seating.
The restoration was then pretreated with IPS Ceramic
Etching Gel (Ivoclar Vivadent), 5% hydrofluoric acid, to ensure
an adequate bonding surface would be achieved (Fig. 7). If the
restoration is already treated with ceramic etching gel in the
dental lab, it can be cleaned after try-in with a cleaning paste
(Ivoclean, Ivoclar Vivadent) to ensure salivary contamination
would not occur (Fig. 8). An additional treatment with etching
gel is then not necessary. A universal single-component restorative
primer (Monobond Plus, Ivoclar Vivadent) was then
applied to the internal surface of the restoration (Fig. 9), allowed
to sit for 60 seconds, and then air-dried.
Before the application of the universal resin cement
(Multilink Automix) to the internal surface of the restoration
(Fig. 10), the surface of the tooth was pretreated. The preparation
was isolated and thoroughly cleaned with a fluoridefree
paste (Proxyt RDA 36, medium, Ivoclar Vivadent) (Fig.
11). A self-etching primer (Multilink A/B) was then dispensed,
mixed and evenly applied to the preparation surfaces
for 30 seconds, starting with the enamel surface. The excess
was dispersed with blown air until the mobile liquid film was
no longer visible. As the primer is solely self-curing, light-curing
is not necessary (Figs. 12, 13). The restoration was seated
and stabilized (Fig. 14).
The restoration was then partially light-cured in quarter segments
(e.g., mesio-oral, disto-oral, mesio-buccal, disto-buccal)
according to the manufacturer’s instructions (Fig. 15). After
that, excess cement was removed using a scaler (Fig. 16). A liquid
strip (Air Block Liquid Strip, Ivoclar Vivadent) was placed
to protect the cement line from oxygen exposure during the curing
process (Fig. 17). This prevented the formation of an inhibition
layer, assuring the clinician of excellent restoration
margins. Final light-curing was completed according to the
manufacturer’s instructions (Fig. 18).
The restoration margin was polished with a silicone polishing
system (OptraPol Next Generation, Ivoclar Vivadent) (Fig.
19). After, the restoration was coated with a fluoride varnish
(Fluor Protector S, Ivoclar Vivadent) and allowed to dry for 60
seconds to further protect the tooth structure after chemical and
mechanical treatment (Fig. 20). Occlusion and aesthetics were
then verified, and both the patient and dentist were pleased with
the new restoration (Fig. 21).
Advanced materials such as IPS e.max and Multilink Automix
Next Generation enable clinicians to provide long-lasting, highly
aesthetic restorations for a variety of indications. These materials
also eliminate previous restrictions on where certain materials can
be used, as they are designed to address all issues surrounding
restoration fabrication and placement. Thus, patients can benefit
from these advancements in restorative dentistry when they request
or require treatments that are both functional and aesthetic.