1.
Nishu Priya
III PGT
Journal club

2.
Introduction
• Titanium implant abutments are widely used due to their optimal physical and mechanical
properties, including high strength and biocompatibility.
• However, these abutments compromise the esthetic appearance of the final restoration due to their
gray color, especially in patients with thin mucosa.
• Over time, the development of ceramics and computer-aided design and computer-aided
manufacturing (CAD/CAM) systems, along with an increasing esthetic demand of patients, led to the
fabrication of all-ceramic abutments that improved the esthetic outcome of treatments.
• High-strength ceramics, including zirconia, are now an optimal option for the fabrication of implant
abutments.

3.
One-piece zirconia abutments have several shortcomings.
Evidence shows titanium abutments have a significantly better fit than zirconia abutments as
ceramics cannot be machined as accurately as metals.
High rate of fracture is another drawback of one-part zirconia abutments, which either occurs at the
implant–abutment connection or in the transmucosal part of the abutment.
One-piece zirconia abutments

4.
In contrast, significant differences in the physical properties of zirconia and titanium,
especially, in terms of hardness and modulus of elasticity, can cause wear and damage
to the internal components of the implant fixture.

5.
• Due to the aforementioned limitations, the idea of
hybrid abutments was suggested.
• Hybrid abutments consist of a titanium insert,
which is connected to a ceramic mesostructure
using a resin cement
• These types of abutments have the advantages
of both ceramic and titanium abutments,
including improved esthetics, optimal
biological response, and superior mechanical
properties, with no adverse effects on the
implant–abutment interface.
Two-piece zirconia abutment

6.
Pre-crystallized lithium
disilicate
• Introduction of pre-crystallized lithium disilicate blocks (IPS-Emax
CAD), which have a perforation that provides an intimate fit with the
titanium insert, enabled the fabrication of monolithic implant-
supported restorations even with the chair-side CAD/CAM systems.
• The monolithic nature of restorations prevents some complications
such as ceramic fracture and chipping.
• Lithium disilicate abutments can be used in the form of hybrid
abutment with a separate crown or hybrid abutment-crown with the
abutment and crown fabricated as one piece, which will then be
bonded to the titanium insert.

7.
Hybrid ceramic
blocks
• Polymer-infiltrated ceramic network material is a new category of
materials with an interconnected dual network structure of ceramic
and polymer (VITA ENAMIC, Vita Zahnfabrik).
• This group of materials has the advantages of both ceramics
(optimal durability and color stability) and composite resins
(improved flexural properties and low abrasiveness).
• Enamic by VITA is among these materials, which is composed of
a pre-sintered feldspathic ceramic reinforced by a polymer
network.
• The Enamic-perforated blocks used for the fabrication of
monolithic screw-retained implant-supported restorations have an
integrated connection, which is compatible with the titanium
bases.
• Restorations fabricated using these materials do not require

8.
CAD CAM Polymethyl methacrylate blocks
• Polymethyl methacrylate blocks (Telio CAD and VITA CAD temp)
are indicated for implant-supported, long-term provisional single
restorations for the purpose of soft tissue management.
• These blocks are available with a connection geometry for
attachment to a titanium insert.

9.
Digital vs Conventional workflow
• Hybrid abutments may be produced in a digital or conventional workflow.
• In the conventional method, the abutment crown is formed over the prefabricated titanium base
with wax that will be transferred to lithium disilicate through the pressing technique (IPS e.max
Press).
• The restoration should be tried in the oral cavity prior to bonding the hybrid abutment/crown to
the titanium base due to the required correction.
• In the digital technique, a digital impression is made either from the oral cavity by a scan
body/scan post or from the cast.
• The proper titanium insert is selected according to the implant system and then CAD/CAM
software is intended to design and fabricate the abutment or abutment/crown.

10.
Effect of peri-implant soft tissue and bone
• The mucosal attachment formed around titanium or ceramic
abutments is composed of two parts: junctional epithelium and
connective tissue.
• Mehl et al assessed the effect of hybrid abutments made of zirconia
or lithium disilicate bonded to a titanium base by resin cement on
peri-implant tissues. They revealed that the abutment material and
the use of two-piece abutments with adhesive resin joint had no
significant effect on bone loss and soft tissue anatomy except that the
height of junctional epithelium was longer around one-piece titanium
abutments compared with two-piece zirconia abutments.
• Mehl et al, in another study, demonstrated that two-piece implant
abutments with a machined surface led to better adhesion of host
cells than abutments with a polished or rough surface.
• Both studies confirmed the biocompatibility of zirconia and lithium

11.
Mechanical properties
• A recent systematic review showed that titanium inserts bonded to zirconia increased the overall
fracture resistance, prevented the implant connection wear, and resulted in better marginal fit
compared with one-piece zirconia abutments.
• Elsayed et al concluded that hybrid ceramic abutment made of zirconia and lithium disilicate can
tolerate heavier loads compared with the physiologic loads applied to the anterior region (150–235 N).
• Therefore, they are suitable treatment options for single implant rehabilitation in the anterior region.
• Nouh et al demonstrated that zirconia hybrid abutment fracture resistance was significantly higher
than that of lithium disilicate.
• Therefore, these restorations can be successfully used in the clinical setting for rehabilitation of the
premolar region.

12.
Mode of failure
• Application of a fragile material on natural teeth is not problematic due to the presence of periodontal
ligament, while the same material may cause a range of mechanical complications, including fracture
and chipping when applied as implant restorations.
• Nouh et al, observed failure in both titanium base (bending and fracture) and ceramic supra-structure
(fracture and adhesive failure).
• Elsayed et al reported that the most common failure mode in one-piece zirconia abutments was a
fracture at the abutment-implant connection slightly higher than the implant shoulder, while permanent
plastic deformation of the abutment screw and internal connection of titanium base or distortion of the
labial platform of the implant was observed, with no fracture in the ceramic, in zirconia and lithium
disilicate hybrid abutments with a titanium base.
• In addition, Rosentritt et al. reported the bending and fracture of abutment screws as the most common
failure modes of hybrid abutments.

13.
A 57-year-old woman presented with a chief complaint of being unhappy with how her front
teeth looked when she smiled .

14.
Clinical examination revealed endodontic treatment in tooth 8, and the root canal was obturated with
gutta-percha. Periapical radiographs revealed that tooth 8 had a fiber post, and teeth 7, 9, and 10 had
defective proximal composite resin restorations. The insufficient tooth structure indicated the need for
full-coverage crowns.

15.
Tooth 8 had recurrent decay 2–3 mm beyond the cemento-enamel junction and was considered
non-restorable. Treatment options other than an implant included crown lengthening; this was not an
optimum option, as it would require excessive bone removal for a greater biological width. Consequently,
tooth 8 would not appear esthetic, being 2–3 mm longer than the adjacent tooth. Orthodontic extrusion
would result in a cervical neck narrower than that of tooth 9, resulting in a large black triangle. Therefore,
we opted for tooth extraction and immediate implant placement. A traumatic extraction was performed for
tooth 8 under local anesthesia.
An implant (Nobel
Speedy Replace, Nobel
BioCare, Zürich,
Switzerland) with a
4.3-mm diameter and
13-mm length was
placed in the extraction
socket; thereafter, a 4.3
× 3-mm Ti -based
healing abutment was
placed

16.
Follow-up appointments at
1 week [Figure 3c] and 2
months [Figure 3d] showed
that the soft tissue responded
favorably, and bone
augmentation was left to heal
for 4 months.
Provisional crowns were
splinted and fabricated
from bis-acryl as a 4-unit
provisional fixed dental
prosthesis (FDP) [Figure
4a-c] modified per the
patient’s
Request.

17.
An NB-RS 4.3-L Ti-base (Dentsply Sirona
Ti-base; InLab, Bensheim, Germany) was
scanned using Cerec AC Connect with
Omnicam (Dentsply Sirona, York, PA,
USA).
The customized zirconium oxide abutment
was designed using a digital software (inLab
SW4.2, Dentsply Sirona, York, PA, USA).
The zirconia abutment was milled from
a pre-sintered meso Zr shade F0.5 block
(InCoris TZI, Sirona GmbH, Germany) using
a milling production unit.
The Ti-base outer surface
and Zr-abutment intaglio
were sandblasted with
50-μm aluminum oxide.
RelyX Ultimate was used
to connect the Ti-base
with the Zr-abutment and
tried-in as one piece

18.
Definitive crowns for the implant abutment and prepared teeth were fabricated from
low-translucency IPS e.max Press LD.

19.
Discussion
• Clinicians strive to improve implant crowns and their biomechanical and esthetic
characteristics.
• Screw-retained implants possess retrievability and are usually the first option to eliminate
excess cement from extruding on the platform, especially for deeply placed implants.
• In this case, it was evident with the provisional crown that the screw-access channel was
from the incisal edge, and covering the definitive crown screw-access channel with
composite on the incisal surface would not be esthetically acceptable.
• Accordingly, a cement-retained crown design was chosen for our implant; retrievability might
not be a feature in cement-retained crowns, but they respond to functional loads differently.
Thus, abutment-screw loosing is not a major concern.

20.
• The Procera copy milling system produces a Ti abutment without needing the casting step, as
it does not rely on wax bur-out. This reduces the abutment fabrication time, but the metallic
color remains.
• The implant was placed 4–5 mm apical to the adjacent cemento-enamel junction so that the
apical portion engaged the more native bone.
• If an LD crown was directly cemented on a Ti abutment intraorally, there would be flow of
excess cement material and its extrusion close to the implant platform. Furthermore, the LD
would be in direct contact at the 4–5-mm soft tissue area; no data currently shows how the
LD surfaces interact with soft tissue in direct contact.
• A clinical study found no distinct differences in the health of peri-implant mucosa adjacent to
zirconia and Ti abutment surfaces, with both showing favorable responses.

21.
• From an economic point of view, the cost was reduced by half.
• A limitation of this technique is that it requires an additional clinical and laboratory
step when compared with Ti-based monolithic restorations.
• A hybrid-abutment try-in appointment is required to evaluate the zirconia
abutment finish line before proceeding with the definitive restoration; the LD
implant crown was inserted at a later appointment.

22.
Conclusion
The technique presented here eliminated the need for
the casting step and of a high-noble metal
substructure, thus reducing the estimated cost by half.
It also allowed the definitive implant and
teeth-supported LD crowns to blend in with the
adjacent and opposing teeth. Follow-up demonstrated
how the soft tissue surrounding the implant and teeth
had a positive response. Longer follow-ups remain to
be conducted to monitor bone levels upon crown
insertion. Nonetheless, clinicians may use this
alternative approach to fabricate single implant
crowns, as they provide optimum esthetics and
biomechanics in the anterior maxillary region.

23.
A 40-year-old male patient was referred to the dental office with a complaint of smile dissatisfaction
relating to the appearance of their maxillary incisors associated with pain during chewing.
Initial case showing extensive restoration in the anterior teeth and color mismatch of the incisors.
The clinical examination revealed extensive direct restorations in the anterior teeth with
unsatisfactory
color and unusual movement of the crown.

24.
A–F) Implant placement procedure and temporary abutment preparation. (A) Frontal view of the alveolus. (B) Implant installation. (C, D) Abutment installation.
(E) Implant temporary framework installation and (F) adaptation.

25.
Temporary crown individualization. (A) ATeflon tape was used to protect the screw access hole. (B, C) Insertion of acrylic resin at the abutment’s anterior
face, and, the positioning of the individualized veneer. (D) Removal of the unfinished temporary crown. (E, F) The crown in position immediately and after the healing
period.

26.
A metallic link was used for the connection between the zirconia mesostructure and
the abutment

27.
(A–F) Ceramic veneering adhesive cementation. (A) Tooth prepared to receive a veneer and the implant protection with an individualized transfer. (B) Tooth
substrate acid etching. (C) Adhesive system application. (D) Resin cement application on the ceramic veneer intagliosurface. (E) Excess cement removal with a microbrush.
(F) Light activation.

28.
Discussion
Dental implant rehabilitation can be defined as successful when the natural contours of the lost
element are recovered in the prosthesis, achieving harmony with the adjacent teeth.
The final result of the presented clinical case demonstrated the importance of an atraumatic extraction
to preserve the supporting bone tissue and to maintain a large and natural-looking for peri-implant soft
tissue.
Immediate loading by the installation of a well-defined temporary crown with a concave and well
polished emergence profile ensures better tissue resilience after surgery, with almost no unwanted
remodeling, which in turn facilitates the prognosis of the case.
However, it is important that this emergence profile achieved with the temporary crown during healing
is also transferred to the model for manufacturing the final restoration, thereby enabling anatomic
similarity of both temporary and final crowns.

29.
The zirconia mesostructure metal link is used to ensure a hybrid abutment with a large amount of
polycrystalline material which diminished the grayish effect on the mucosa;however, it also ensures
the metallic connection between the abutment and crown at the same time, which reduces the
incidence of mechanical problems in this interface.
For this case, the veneering manufacture on the adjacent tooth made in the same material as the
implant-supported crown helped to achieve a final harmonic smile.
However, this restorative modality should only be performed when the healthy tooth has the
indication for it, as in this case.
As a study`s limitations the radiographs are not available.

30.
Conclusion
• In esthetically challenging treatments, ceramic abutments provide more natural outcomes
than traditional titanium abutments.
• In two-piece ceramic abutments, the presence of titanium inserts can overcome the
brittleness of ceramic, improve fracture resistance, and prevent wear and damage to the
internal connection of the implant fixture.
• In contrast, the monolithic nature of these restorations prevents some mechanical
complications including ceramic chipping.
• Furthermore, extraoral cementation reduces the possibility of peri-implantitis.
• Although hybrid abutments are recommended by in vitro studies as a promising treatment
option, there is a strong need for long-term clinical studies to evaluate the clinical
performance of these abutments. Therefore, this type of abutment should be used bearing
the current limitations in mind.

31.
Reference
s
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2. Alqarawi FK. Enhancing the esthetics of a maxillary
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report. Saudi J Med Med Sci 2022;10:170-4.
3. Adolfi D, Tribst JP, Adolfi M, Dal Piva AM, Saavedra
GD, Bottino MA. Lithium disilicate crown, zirconia hybrid
abutment and platform switching to improve the
esthetics in anterior region: a case report. Clinical,
cosmetic and investigational dentistry. 2020 Feb 19:31-
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