Feldspathic veneers: What are their indications?

Abstract

Many different materials and treatment options are available in esthetic and restorative dentistry. Various newer products, such as pressed ceramics, offer enhanced functionality; however, in thinner dimensions, they lack the inherent esthetic beauty of traditional materials such as feldspathic porcelain. As patient demands for better esthetics have increased in recent years, so too has the need for restorative materials that closely mimic the patient's natural dentition. Initially used for the creation of porcelain dentures, feldspathic porcelain has emerged as the premier esthetic material for custom veneer restorations. In recent years, the use of hand-layered powder/liquid feldspathic porcelain has been revived based on its highly esthetic values and little-to-no preparation requirements. By keeping preparation to a minimum, less tooth structure is lost and procedures are much less invasive, which is exactly what patients desire.

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2 Compendium November | December 2010—Volume 31, Number 9
B
ased on their strength, longevity, conservative
nature, biocompatibility, and esthetics, veneers
have been considered one of the most viable treat-
ment modalities since their introduction in 1983.
1,2
Still
in use today, porcelain laminate veneers have undergone a
significant evolution, spreading across the globe for treat-
ment of various indications.1 Once considered merely as
simple coverings for anterior teeth, the use of veneers has
expanded into different indications, including coverage
of coronal tooth structures.1
Interestingly, today’s philosophy of using no-preparation
or minimal preparation veneers is not new.
3
In the early
1980s, innovative concepts of bonding thin pieces of porce-
lain to teeth with little-to-no tooth preparation were devel-
oped to satisfy patients’ needs.4,5 Using layered feldspathic
porcelain, these veneers were placed on the facial surfaces
of the teeth to create highly esthetic results.5
Unfortunately, due to the advent of pressable materials
and computer-aided design/computer-aided manufacturing
(CAD/CAM) technology, the customization and high es-
thetic value typically seen in feldspathic veneers is being lost
or diminished.
6,7
In some ways, the art of creating beautiful
hand-layered feldspathic veneers is akin to the ancient art of
Venetian glass blowing.
8
For example, a talented and artistic
glass blower creates a unique, customized piece that is far
superior and much more stunning than something mass-
produced and available at a typical retail store. However, just
as a talented glass blower undergoes challenges in creating
the perfect piece, so do dental ceramists.8
MATERIAL CHARACTERISTICS
OF FELDSPATHIC PORCELAIN
Feldspathic veneers are created by layering glass-based (ie,
silicon dioxide) powder and liquid materials.8,9 Silicon di-
oxide, also referred to as silica or quartz, contains various
amounts of alumina.8,9 When these aluminosilicates are
found naturally and contain various amounts of potassium
and sodium, they are referred to as feldspars.8,9
Feldspars are typically modified in different ways to create
glass that then can be used in dental restorations.8 Synthetic
forms of aluminosilicate glasses also have been developed for
use in dental ceramics.8 Whether these synthetic porcelains
perform equally or better to naturally occurring feldspar is
still debated.8
ORIGINAL FELDSPATHIC VENEERS
Feldspathic porcelain was the key material for creating por-
celain denture teeth.
8,9
This material provided great esthetic
Feldspathic Veneers:
What Are Their Indications?
Edward A. McLaren, DDS, MDC;1 and Brian LeSage, DDS, FAACD2
1 Professor, Founder, and Director, UCLA Post Graduate Esthetics; Director, UCLA Center for Esthetic Dentistry;
Founder and Director, UCLA Master Dental Ceramist Program, UCLA School of Dentistry, Los Angeles, California
2 Founder and Director, UCLA Esthetic Continuum; Founder and Director, Beverly Hills Institute of Dental Esthetics;
Private Practice, Beverly Hills, California
Abstract: Many different materials and treatment options are available in esthetic and restorative dentistry. Various
newer products, such as pressed ceramics, offer enhanced functionality; however, in thinner dimensions, they lack the
inherent esthetic beauty of traditional materials such as feldspathic porcelain. As patient demands for better esthetics
have increased in recent years, so too has the need for restorative materials that closely mimic the patient’s natural
dentition. Initially used for the creation of porcelain dentures, feldspathic porcelain has emerged as the premier esthetic
material for custom veneer restorations. In recent years, the use of hand-layered powder/liquid feldspathic porcelain
has been revived based on its highly esthetic values and little-to-no preparation requirements. By keeping preparation
to a minimum, less tooth structure is lost and procedures are much less invasive, which is exactly what patients desire.
REVIEW/OPINION

McLaren and LeSage
www.compendiumlive.com Compendium 3
value and demonstrated high translucency, just like natural
dentition.9 Experts in porcelain layering and veneering later
would stack this fine powder and liquid material onto a core
composed of metal, alumina, or zirconia to create esthetic
restorations.8
By using a layering and firing process, ceramists then
began developing veneers that could be made as optically
close to natural teeth as possible.9 When feldspathic ve-
neers were introduced, they presented 0.5 mm of thickness
and tapered down to practically nothing at the margins.3
Refractory dies and platinum foil techniques were used to
fabricate feldspathic porcelain veneers.8
Feldspathic veneers could be placed conservatively be-
cause the porcelain could be layered very thinly.9 Significant
loss of tooth structure was not an issue; the veneers were
so thin that they could be placed directly on the enamel.9
A major concern with feldspathic porcelain veneers, how-
ever, was their strength, which was only approximately 70
MPa to 90 MPa.
9
Also, when the veneers were placed without
preparation, periodontal problems could occur as a result of
overcontoured teeth with unnatural emergence profiles.10
After much research, however, it was determined that
feldspathic veneers would last long term, especially when
bonded to enamel. Therefore, to preserve the health of the
gingival tissues and prevent overcontouring, a slight 0.5-mm
reduction of tooth surface was found to work best.
3
Because
the feldspathic veneers were typically 0.5 mm, the lost tooth
structure was replaced and the original emergence profile
was nearly restored.3
To solve the perceived issues regarding strength, other
types of porcelains were developed by manufacturers.11
However, challenges arose when trying to create very thin,
minimally prepared veneers using these new materials.8
PRESSED CERAMIC VENEERS
To correct the low-strength problem, manufacturers intro-
duced products to replace feldspathic porcelains as a veneer
material.8 These new materials, termed pressable ceramics,
were manufactured to be extremely dense and demonstrated
much higher strength ratings, such as flexural strengths up
to 180 MPa.8 Due to their improved strength and com-
position, pressed ceramics were considered ideal for many
indications, including inlays and onlays, anterior crowns,
bicuspid crowns, veneers, and posterior crowns.8
Pressed ceramic restorations were fabricated using the
lost-wax technique.12 The first step was to wax a pattern
onto a die, which was then invested and burned out.
12
Small
ceramic discs, called ingots, were then melted to a thick
liquid consistency and pressed into a pattern.12 The final
step was to layer powder or liquid porcelains onto the fab-
ricated and pressed restorations.12 This enabled technicians
to make the pressed blocks more esthetically pleasing to the
patient.12 In addition, pressed ceramics could be waxed to
full contour, which continues to be a significant advantage
of this type of porcelain.13 However, these full-contour
restorations often appeared monochromatic and required
superficial surface staining and glazing in order to build in
the esthetics. Unfortunately, this process tended to lower the
Figure 2 Try-in of a “mini” no-preparation veneer.
Figure 1 Patient presented with preoperative conditions
and a desire to close diastemas.
Figure 3 Four polished no-preparation “mini” veneers,
postcementation.

Review/Opinion
4 Compendium November | December 2010—Volume 31, Number 9
optical “value” of the restoration and further, these built-in
esthetic effects would be lost if any adjustments were needed
to the restoration postcementation, or over time as a result
of in vivo wear.
As CAD/CAM technologies developed, the availability
of computerized pressing and milling machines further sim-
plified this process by developing blocks of pressed materi-
als into the exact size and shape necessary to complete the
restoration.8 CAD/CAM technology for veneers, however,
is still an evolving, yet promising, modality.
These processes were well accepted by technicians and
laboratories because they were already accustomed to the
waxing techniques that had been used in the past to create
metal- and alloy-based restorations and because CAD/CAM
machines were becoming more readily available.8,12 These
materials, however, required more room for incorporating the
optical nuances of dentin and enamel, making more aggressive
tooth preparation necessary in order to keep the veneers within
the natural emergence profiles.12 Conventional feldspathic
veneers required tooth reduction only up to 0.5 mm, and
it was possible to work in dimensions down to 0.3 mm.14
Con versely, pressed ceramics required at least 0.75 mm or
more of reduction.14
Another issue with pressed ceramics was their tendency
to appear less transparent and less esthetically pleasing than
traditional feldspathic veneers.9 These new pressed materi-
als tended to appear more opaque and monochromatic and
required the addition of extra veneering porcelain to match
the natural dentition.
8,9
Newer versions of pressed ceramics
are more translucent. However, in the authors’ experience,
such materials still require an average thickness of 0.8 mm
or more for workability and high esthetics.
TODAY’S MINIMAL OR NO-PREPARATION
FELDSPATHIC VENEERS
As patients have begun requesting less invasive treatments
and higher levels of esthetics, the use of feldspathic veneers is
resurging.6,7 With this comes the desire for thinner veneers
and preservation of natural tooth structure.
6,7
The feld-
spathic veneers of today allow ceramists to create thicknesses
of less than 0.5 mm, which can be fabricated to a minimum
thickness of 0.3 mm.
3
Through the use of advanced bonding
agents, the capacity to predictably bond veneers to enamel
is great, as well.6,7
Many ceramists today are not being trained in the art of
sculpting powder/liquid porcelains to form the highly esthet-
ic feldspathic veneers, especially thin veneers.8 This creates
a problem because the esthetic value exhibited in these res-
torations depends on the ceramist’s ability to build depth of
color and translucency into the restoration.8 Dentists and
their ceramists must also know when it is appropriate to use
this slightly weaker restorative material in order to prevent
post-treatment fracture issues.8
INDICATIONS
Although pure porcelain-bonded restorations are the most
conservative and esthetic restorations, they are also the
weakest.15 Therefore, important parameters and guidelines
must be followed when undertaking a restoration fabricated
from powder/liquid feldspathic porcelain veneer materi-
als.15 Generally, feldspathic porcelain materials are indicated
for anterior teeth when significant enamel is remaining.8
Occasionally, feldspathic porcelains may be used on bicus-
pids, but rarely on molars.8 In the case of molars, all risk
assessments must present as low as possible.8 Bond main-
tenance through absolute ideal isolation procedures during
cementation, or what has been described as protection of
the internal surface of these restorations, is also absolutely
necessary for long-term success.8
Of the many factors to consider, space requirement is
important and can affect the outcome of the finished resto-
ration.9 When creating a feldspathic porcelain veneer, it is
necessary to realize that the space required for shade change
ranges from 0.2 mm to 0.3 mm per shade.
9
It is also impor-
tant to consider the condition of the substrate to which the
veneers will be bonded.9 To successfully bond feldspathic
veneers, the requirements that must be met include 50%
or more enamel on the tooth, 50% of the bonded substrate
must be enamel, and 70% or more of the margin must be
in enamel.8 It is always preferable to preserve the cingulum
and lingual marginal ridges, as these anatomic landmarks
provide the tooth with more than 80% of its strength.8,16
When deciding whether to use feldspathic veneers, it
is also necessary to undertake a flexural risk assessment.
8
Flexural risk tends to be higher when bonding to higher
levels of dentin because dentin tends to be more flexible than
enamel.8 If bonding to enamel, the flexural risk is low to
moderate.8 A simple but strong determinant of tooth flexure
is to observe mesial-distal craze/fracture lines on the lingual.
Tensile and shear stress risk assessments are also necessary
when deciding on feldspathic porcelain veneers.
8
Generally,
higher tensile and shear stresses occur when there are large
areas of unsupported porcelain, deep overbites or overlaps of
teeth, bonding to more flexible substrates such as dentin and

McLaren and LeSage
www.compendiumlive.com Compendium 5
composite, bruxism is present, and the restorations are placed
more distally.8 In these higher-risk clinical situations, a pressed
or machined glass ceramic should be considered.8 Finally, there
must be an absolute low risk of bond and seal failure when
placing restorations fabricated from feldspathic porcelain.8
CASE STUDY 1
In this case, “mini” no-preparation veneers were used as an
alternative to direct composite veneers. The patient presented
wanting to close the diastemas (Figure 1). Impression taking
required only 10 minutes. At the cementation appointment,
the veneers were tried in (Figure 2), and the cementation
and finishing protocol required only 30 minutes (Figure
3). Although this case necessitated two appointments, the
fact that no preparations were required made the overall
restorative process time efficient.
CASE STUDY 2
In the case of a patient presenting with a request for longer,
fuller teeth and diastema closure (Figure 4), extended veneers
with minimal preparations mostly in enamel were planned
(Figure 5 and Figure 6). These veneers covered the facial
and lingual aspects (Figure 7), and a “taco shell” prepara-
tion design was incorporated on the lateral and distal of
Figure 5 Facial view of minimal preparations.
Figure 9 Postcementation view of the extended coverage
porcelain veneers.
Figure 7
View of anticipated porcelain restorations on the cast.
Figure 4 Preoperative view of a patient presenting with a
desire for longer, fuller teeth and diastema closure.
Figure 8 Internal view of the “taco shell” veneer design.
Figure 6 Incisal view of minimal preparations.

Review/Opinion
6 Compendium November | December 2010—Volume 31, Number 9
the central incisors (Figure 8). Overall, this case exemplifies
the use of minimal preparation veneers when the criteria
for Category 1 ceramic use are met (Figure 9). (For further
explanation of Category 1 use, see the article “Ceramics:
Rationale for Material Selection” on page XX of this issue
of Compendium.)
CASE STUDY 3
A 35-year-old female presented with teeth that were un-
sightly due to chipping, severe wear, unnatural contours,
and gingival asymmetry (Figure 10). In addition, pre-existing
composite restorations were on the mesial aspects of teeth
Nos. 9 and 10, and diastemas also were present (Figure 11).
In this era of minimally invasive dentistry, tooth preservation
should be every clinician’s goal.
Due to the severe damage and occlusal pathology evident
in this patient’s dentition, an occlusal equilibration and com-
posite mock-up for more than 5 months was performed as trial
occlusal therapy to test the proposed new length and contours.
The patient was comfortable and stable during this time.
Figure 11 Retracted view of a patient’s preoperative
condition.
Figure 15 Portrait view of the patient displaying a confident
postoperative smile.
Figure 13 Retracted postoperative view revealing the
patient’s restorations.
Figure 10 Preoperative view of a patient’s natural smile.
Figure 14 Postoperative view of the patient’s natural smile.
Figure 12 View of the minimally invasive preparations on
teeth Nos. 6 to 8, and 0.5-mm depth cuts demonstrated on
teeth Nos. 9 to 11.

McLaren and LeSage
www.compendiumlive.com Compendium 7
Using a putty matrix fabricated from the diagnostic wax-
up, a bis-acrylic preparation guide was applied to the teeth.
Preparations consisted of placing 0.5-mm depth cuts into the
incisal and facial aspects of the bis-acrylic preparation guide.
A modified prepless veneer preparation (ie, according to a
classification system developed by one of the authors) was
made on teeth Nos. 6 to 8, with the depth cutting grooves
minimizing the potential for overpreparation.
With minimal preparation and based on the patient’s
desire for maximum esthetics, stacked feldspathic porcelain
veneers (Creation, Jensen Dental, www.jensendental.com)
were planned for teeth Nos. 6 to 11. Completion of the
minimally invasive, stacked feldspathic porcelain veneer
treatment resulted in enhanced smile esthetics (Figure 13
and Figure 14) and a conservative and pleasing outcome
(Figure 15).
CONCLUSION
Patients today demand much more from their dentists and
laboratory ceramists.
1
As a result, highly esthetic restorations
and minimal-to-no preparation restorations are no longer
mutually exclusive. Therefore, dental professionals must
consistently find a way to select treatment options that focus
on the patient’s best interest. With this in mind, a recent
resurgence in the use of conventional feldspathic porcelain
veneers has developed.7
These conventional dental restorations are generally in-
dicated for anterior teeth and occasional bicuspid use; rare
molar placement would be acceptable only when all risk
parameters are at the least risk level.
8
In addition, feldspathic
porcelain veneers are ideal when significant enamel remains
on the tooth and generally when there is low flexure and
stress risk assessment.8 Finally, these restorations absolutely
require long-term bond maintenance for success.
With increased patient demands for enhanced esthetics
and a need for restorative materials that closely mimic the
patient’s natural dentition, feldspathic porcelain represents
the premier esthetic material for custom restorations that
are conservative and predictable for appropriate indications.
Based on its high esthetic value and little-to-no preparation
requirements, feldspathic porcelain enables dentists and their
ceramists to provide esthetic treatments that are much less
invasive, which is precisely what patients expect.
ACKNOWLEDGMENTS
The dentistry and laboratory work for Cases 1 and 2 were
performed by Dr. McLaren. The dentistry for Case 3 was
performed by Dr. LeSage, and the laboratory work was per-
formed by Domenico Cascione, CDT, BS, from Burbank
Dental Laboratory.
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