CLINICAL RESEARCH 354 THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY Correspondence to: Gil Tirlet 234 Boulevard Raspail, 75014 Paris, France. Tel : +33 43204130: E-mail: [email protected]Ceramic adhesive restorations and biomimetic dentistry: tissue preservation and adhesion Gil Tirlet Senior Lecturer, Department of Prosthetic Dentistry, Faculty of Dental Surgery, Paris Descartes University, Paris, France Private Practice Specializing in Esthetic Dentistry, Paris, France Hélène Crescenzo Ceramic Dental Technician, Espace Diamant, Cogolin, France Dider Crescenzo Ceramic Dental Technician, Espace Diamant, Cogolin, France Panaghiotis Bazos, DDS Emulation, Athens, Greece
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CLINICAL RESEARCH
354THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Correspondence to: Gil Tirlet
234 Boulevard Raspail, 75014 Paris, France. Tel : +33 43204130: E-mail: [email protected]
Ceramic adhesive restorations
and biomimetic dentistry:
tissue preservation and adhesion
Gil TirletSenior Lecturer, Department of Prosthetic Dentistry, Faculty of Dental Surgery,
Paris Descartes University, Paris, France
Private Practice Specializing in Esthetic Dentistry, Paris, France
Hélène CrescenzoCeramic Dental Technician, Espace Diamant, Cogolin, France
Dider CrescenzoCeramic Dental Technician, Espace Diamant, Cogolin, France
Panaghiotis Bazos, DDS
Emulation, Athens, Greece
TIRLET ET AL
355THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Abstract
Thanks to sophisticated adhesive tech-
niques in contemporary dentistry, and the
development of composite and ceramic
materials, it is possible to reproduce a
biomimetic match between substitution
materials and natural teeth substrates.
Biomimetics or bio-emulation allows for
the association of two fundamental par-
ameters at the heart of current therapeu-
tic treatments: tissue preservation and
adhesion. This contemporary concept
makes the retention of the integrity of
the maximum amount of dental tissue
possible, while offering exceptional clin-
ical longevity, and maximum esthetic
results. It permits the conservation of
the biological, esthetic, biomechanic-
al and functional properties of enamel
and dentin. Today, it is clearly possible
to develop preparations allowing for the
conservation of the enamel and dentin in
order to bond partial restorations in the
anterior and posterior sectors therefore
limiting, as Professor Urs Belser from
Geneva indicates, “the replacement of
previous deficient crowns and devital-
ized teeth whose conservation are justi-
fied but whose residual structural state
are insufficient for reliable bonding.”1
This article not only addresses ceramic
adhesive restoration in the anterior area,
the ambassadors of biomimetic dentist-
ry, but also highlights the possibility of
occasionally integrating one or two res-
torations at the heart of the smile as a
complement to extensive rehabilitations
that require more invasive treatment.
(Int J Esthet Dent 2014;9:354–369)
355THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
CLINICAL RESEARCH
356THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Introduction
Biomimetics is the reproduction or copy
of a model or a standard.2,3 More pre-
cisely, the notion of biomimetics consists
of reproducing and artificially imitating
natural systems in living organisms.
Biomimetics is an emerging interdisci-
plinary field in materials science, engi-
neering, and biology, in which lessons
learned from a biological standard form
the basis for novel technological ma-
terial innovation. It involves the inves-
tigation of both structures and physi-
cal functions of biological composites
of engineering interest, with the goal of
designing and synthesizing new and
improved materials.
The term bio-emulation was intro-
duced as a new expression for the dis-
cipline of dentistry, corresponding to
the reproduction of the natural model
via spatial, structural and optical histo-
anatomic emulation.4 In contemporary
dentistry, the concept of biomimetics
is a true synonym for natural integra-
tion,3 meaning biological, biomechan-
ical, functional and esthetic integration,
which closely mimicks the physiological
behavior of the natural tooth.3,5
Because of sophisticated adhesive
techniques and the progress that has
been made in ceramic adhesives, today
it is possible to produce a biomimetic
match between esthetic substitution ma-
terials and the anatomical substrates of
the natural tooth.
Biomimetics associates two funda-
mental attributes at the core of modern
care: tissue preservation and adhesion.
It Is undisputable that this concept has
had the most profound effects on the
paradigms of modern restorative den-
tistry. As Pascal Magne points out,3 the
concept of modern biomimetics can
be summarized into three distinct, but
closely linked, categories:
Observation of nature, biology, its
role, its mechanical behavior, and
its optical characteristics
Respect of nature in preparing a
minimal dental tissue
Reproduction of nature using
adhesion and modern biomaterials
(composites and ceramics)
Reference model:
the natural tooth
Natural teeth are the physiological result
of a subtle association between enam-
el, rigid and breakable, and the dentin,
resilient and flexible. From a functional
point of view, dentin cannot exist if an
enamel shell does not cover it.3 These
two tissues are associated and joined
together by an incredibly rich anatom-
ical interface called the dentoenamel
junction (DEJ). It is capable, through
the intermediary of large fasces of col-
lagen fibers to deflect and to impede the
spreading of crevices in the enamel due
to plastic deformation.3
Thus, due to its role as a buffer and
stress absorber, it is a reference model
for adhesive systems and polymer adhe-
sives used for reinforcing the biomech-
anical integrity of dental crowns5 (Fig 1).
Substitution model: adhe-
sive ceramic restorations
The replacement of the enamel shell with
a soft material, such as composites, only
TIRLET ET AL
357THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
allows for a partial restitution of the rigid-
ity of the dental crown. From this point of
view, the choice of ceramics allows for a
faithful restitution of this rigidity.2,3
Furthermore, aging is synonymous
with the volumetric reduction of the
enamel layer, and thus, an increase in
the flexibility of the tooth due to its de-
creasing rigidity.
The restitution of the original volume
of the enamel thus represents an esthet-
ic as well as a biomechanical approach.
Adhesive bonding technology and ce-
ramics have the ability to reverse and
resist the effects of aging on teeth.3 For
the aforementioned reasons, a rational
selection of restorative materials proves
to be essential.
Another essential point is the mater-
ial to combination ratio. The CER/COMP
ratio should ideally be superior to 3. This
is of great importance, due to the con-
tracting of polymers in the bonding com-
posite, and the differences in thermal
expansion between the two materials.
Thus, for an average bonded joint den-
sity of 100 mm, the ideal density of the
veneer should be a minimum of 300 mm.
A ratio inferior to the critical level of 3 will
have important consequences in terms
of potential failure rates of the restoration
(fissures and cracks in the ceramic ad-
hesive restoration).3
Therefore, the changing of paradigms
must be accompanied by the progres-
sive passage from full coverage ce-
ramic restorations to partial coverage
ceramic restorations.6 The latter may
take the form of inlays, onlays, overlays,
veneerlays in the posterior sector and
in veneers, half veneers or chips in the
anterior sector.6 The scope of this article
aims to address the various partial cov-
erage ceramic adhesive restorations in
the anterior sector.
The recognition of the importance of
the integrity of dental tissue is the focus
of biomimetics. An analysis of these last
points is critical following the removal of
a prior restoration, trauma, or the elimi-
nation of a decayed lesion, in order to
economize hard tissue removal.
This analysis must be conducted in
conjunction with the occlusion scheme
at hand, with emphasis on the presence
or absence of horizontal and/or oblique
stress, the latter being the most detri-
mental for teeth (eg, supraocclusion,
dental wear, parafunctions, poor align-
ment).
Composites – in part due to their in-
herent low elastic modulus – appear to
be challenged by mechanical stresses,
both masticatory and occlusal, when
replacing large anterior coronal defi-
ciencies.7 In conjunction, the thermal
conduction mismatches them, and hy-
groscopic expansion renders them even
Fig 1 View of the natural incisors photographed
in transmission, allowing for the observation of dif-
ference in thickness between the enamel (of the cer-
vical on the edge of the incisor) and the dentin, as
well as the amelodentin junction.
CLINICAL RESEARCH
358THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
more vulnerable over time.7 Additionally,
composites require relatively frequent,
meticulous clinical maintenance in or-
der for them to reach their approximate
10-year life expectancy. Swift, with a pan-
el of experts, concluded that the more
complex the restoration, the shorter the
longevity.8 This statement partially con-
firms the deficiency in stiffness attain-
ment by composite, in order to recover
the original rigidity – that of enamel.
Thus today, in our clinical approach,
the stratification of anterior composites
may increasingly give way to partial cov-
erage ceramic adhesive restorations in
cases of large anterior coronal deficien-
cies, which are most often required in
adults in situations where stable high
esthetic requirements and longevity are
demanded.9-11 These types of restor-
ations embody the conservative doc-
trine, undisputedly placing them as the
therapeutic ambassador for modern
biomimetic dentistry.
This article will illustrate four clinical
cases, three of which deal with vital teeth
and one with a non-vital tooth. The clinic-
al situations have been chosen in order
to demonstrate that beyond the biomi-
metic approach (the chosen path for al-
most 20 years of “French” conservative
and esthetic dentistry, today considered
to be modern), the practitioner must de-
ploy all modern therapeutic possibilities
in order to not only treat the damaged
tooth or teeth but also take into consider-
ation the targeted esthetic requirements
of their patients, particularly in regards
to the therapeutic gradient.12
Case studies
Case 1
A 65-year-old woman, concerned about
her central upper incisors, presented for
an esthetic consultation. Her chief com-
Fig 2 Initial situation. Fig 3 Clinical view of preparation with post and
core (POM, Ivoclar/Vivadent on 12) and Partial
preparations with conservation of maximum enamel
on 11 and 21. The thickness of the preparation was
between 0.4 and 0.6 mm thus creating an optimal
enamel surface for bonding.
TIRLET ET AL
359THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Fig 4 Preparation
after curing of the ad-
hesive system on 11.
Fig 6 Final result at 1-week follow-up. Note the
biological and morphological appearance. This
view perfectly illustrates the biomimetic concept
using the “enamel substitution,” allowing the total
recovery of the intrinsic strength of the teeth.
Fig 5 View of the
ceramic adhesive
restoration at bond-
ing. The adhesive
used was Optibond
Solo plus (Kerr).
Fig 7 One-month follow-up with contrastor.
plaint was that she disliked the shape
and the position of 21 and 11 (Fig 2).
The following treatment plan was pro-
posed to the patient: the rehabilitation of
her smile by a new crown on 12 (she pre-
sented gingival inflammation induced
by the actual prosthesis’ overcontour),
as well as two resin-bonded partial-cov-
erage ceramic restorations. Tooth 22
dictated the esthetic outcome and guid-
ed this minimally invasive rehabilitation
(Figs 3 to 7). No crown lengthening in or-
der to correct the gingival margin archi-
tecture was performed since the patient
preferred to avoid additional surgery.
Although a lack of symmetry among the
anterior teeth can be observed, the pa-
tient’s smile is still harmonious and natu-
ral (Figs 8 to 11).
CLINICAL RESEARCH
360THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Case 2
A 17-year-old patient consulted in or-
der to re-evaluate previous endodontic
work on tooth 21 that was completed 3
years previously following a trauma – it
was discolored due to a root canal. The
therapeutic choice in this case only took
into consideration the biological, bio-
mechanical and esthetic rehabilitation
of tooth 21 per the patient’s esthetic re-
quest (Fig 12).
The composite restoration was fixed
with a stainless steel post and core,
which characterizes conventional den-
tistry based on mechanical concepts
(Fig 13). An initial radiograph was taken,
which displayed the high quality of the
endodontics (Fig 14). The composite
restoration and the stainless steel post
and core were removed (Fig 15).
A dental dam was applied. The crown
presented very good residual tissue. After
sandblasting, etching and the placing of
Fig 8 One-year follow-up (with two lateral softbox).
At this time, we can notice a little gingival injury (me-
sial side on 12) caused by severe tooth brushing.
Fig 10 One-year follow-up: left lateral view of the
smile. The asymmetry in the shape and the dental
composition remains the principal key to the smile’s
expression.13
Fig 9 One-year follow-up. Image taken with con-
trastor (with two lateral soft boxes).
Fig 11 One-year follow-up: right lateral view of
the smile.
TIRLET ET AL
361THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
the adhesive system, flow micro hybrid
composite was applied at the base of
pulpal chamber preceding the placement
of the restoration composite (UD2, Enamel
HRi, Mycerium). A post was not necessary
in this situation due to the important ferrule
effect – the result of the conservation of
residual tissue (Fig 16).
The ceramic adhesive restoration
(e.max MO1, Ivoclar Vivadent) on the
buccal side was prepared, increasing
the enamel surface. A metallic matrix was
Fig 13 The composite restoration is fixed with a
stainless steel post and core.
Fig 15 Clinical view following the removal of the
composite restoration and prior to the removal of the
stainless steel post and core.
Fig 12 Initial clinical situation.
Fig 14 An initial radio-
graph exhibits the high
quality of the endodontics.
Fig 16 Clinical view of 21 with dental dam.
CLINICAL RESEARCH
362THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Fig 17 Preparation of the ceramic
adhesive restoration on the buccal
side.
Fig 19 Final occlusal view with the palatal exten-
sion going beyond the cingulum.
Fig 21 View of the
ceramic adhesive res-
toration at the moment
of bonding. The adhe-
sive used was Optibo-
nd Solo plus.
Fig 18 Completion of the buccal
preparation with an Acteon/Satelec
insert.
Fig 20 View of the Emax MO1 ce-
ramic adhesive restoration.
Fig 22 Radiograph fol-
lowing bonding that dem-
onstrates the perfect fit
and seal of the restoration.
TIRLET ET AL
363THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
connected to a plastic corner (Fender
wedge, Pred), which protected the ad-
jacent teeth. The buccal preparation
was completed with an Acteon/Satelec
insert for finishing two diamond grits: 76
microns and 46 microns to perfectly fin-
ish the margins (Figs 17 to 19). The ce-
ramic adhesive restoration was bonded
(Figs 20 and 21) and a radiograph at-
tested for a good adaptation (Fig 23).
Figures 23 to 26 show the final result and
biomimetic integration after bonding.
Figure 27 shows the clinical result at the
3-year follow-up.
Fig 24 Black and white picture to appreciate
brightness of the single restoration.
Fig 26 Smile integration.
Fig 23 Clinical view one week after bonding.
Fig 25 One-week follow-up (with contrastor).
Fig 27 Three-year follow-up.
CLINICAL RESEARCH
364THE INTERNATIONAL JOURNAL OF ESTHETIC DENTISTRY
Case 3
A 34-year-old man had a large compos-
ite on the left central incisor (21). The
patient refused proposed orthodontic
treatment. He preferred to find another
esthetic solution to restore his tooth. The
suggested treatment consisted of re-
placing the composite restoration with
a ceramic bonded partial restoration
(Fig 28).
Fig 28 Initial situation.
Fig 29 The clinical view of the preparation for the