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The Use of Zirconium in the Management of
Replacing Single Missing Tooth: A Clinical Report
N Hassine1*, R Hadhri1,S Nasri1,B Harzallah2,M Cherif3, and D Hadyaoui2
1Department of Fixed Prosthodontics, Faculty of Dental Medicine, Tunisia
2Professor, Department of Fixed Prosthodontics, Tunisia
3Professor and Head, Department of Fixed Prosthodontics, Tunisia
Submission: November 06, 2017; Published: May 30, 2018
Hadyaoui, Professor, Department of Fixed Prosthodontics, Faculty of Dental
Medicine, Monastir, Tunisia, Email: firstname.lastname@example.org
How to cite this article:N Hassine, R Hadhri, S Nasri, B Harzallah, M Cherif,D Hadyaoui. The Use of Zirconium in the Management of Replacing Single Missing
Tooth: A Clinical Report. Adv Dent & Oral Health. 2018; 9(2): 555756. DOI: 10.19080/ADOH.2018.09.555758
The best treatment option to replace a single missing tooth is usually based on the provision of dental implant. In some cases dental implant cannot be used, for that reason the second treatment option is fixed partial denture. Metal ceramic restorations have been used in fixed prosthodontics for long time, but many disadvantages limits its uses such us the potential metal allergy and the lack of esthetics. On the other hand, the use of all-ceramic materials has known a great increase thanks to the introduction of zirconia to fixed prosthodontics over a decade ago. Zirconia frameworks are manufactured using computer-aided design/computer-assisted manufacturing (CAD/CAM). This high strength material establishes high qualities from the functional, esthetic, and biological points of view. This article describes the use of zirconia for the fabrication of a fixed partial denture restoring both esthetics and function.
Today it’s possible to replace a missing tooth using different treatment modalities. During the past decade, dental implants have been the best choice, especially in cases when the abutment teeth are sound . Nevertheless, implant therapy can sometimes be compromised by anatomical conditions. In fact, implant placement in the posterior maxilla region is often challenging due to alveolar bone resorption and sinus pneumatization phenomenon that are fastened with tooth extraction. To surmount these difficulties, sinus bone grafting and maxillary sinus lifting are frequently indicated . In our case, the Cone Beam–Computed Tomography (CBCT) showed that the alveolar crest is insufficient for implant placement. Also, researches have proved a positive correlation between pre-operative sinus disease and the occurrence of acute post-operative sinusitis in case of maxillary sinus grafting . Consequently, an implant placement cannot be indicated and fixed partial denture seems to be a suitable solution for our case. For fixed dental prostheses the treatment outcome depends on a variety of designs and restorative materials which are available . In recent years, there have been promising results when zirconia frameworks were used as an alternative to metal based fixed partial dentures (FDPs) . Since its introduction in 1960, zirconia attracted the attention of dental researchers with its promising in vitro properties . The qualities that make it a reliable restorative material are superior resistance to fracture
compared to other conventional dental ceramics, biocompatibility, enhanced esthetics and its marginal fit which meets the clinical requirement .
The following case report describes the replacement of the first missing premolar with porcelain fused to CAD/CAM-fabricated zirconia frameworks to design a patient-specific prosthesis.
The case we present here is about a 30 years old female patient with unremarkable medical history, who presented to the Fixed Prosthetics Department of the Dentistry Clinic, University of Monastir. Her chief complaint was to replace the first right maxillary premolar for esthetic and functional reasons (Figure 1).
Concerning her medical history, her only complain was a
chronic sinusitis. Intraoral examination showed that the abutment
teeth were with healthy periodontium and the attached gingiva
was adequate. Resin filling was found on the distal surface of
the upper right canine and the mesial surface of the second right
For prosthetic treatment, two methods were chosen: implant
supported single crown, and zirconia FPD. Implant replacement
was excluded from the list because the measure of the length of
the crest showed that the alveolar crest is insufficient for implant
placement. Moreover, the chronic sinusitis counters the indication
for maxillary sinus floor elevation. Thus, the use of zirconia FPD
was suggested and accepted by the patient. Upon her agreement,
abutment preparation was undertaken. . The design of the tooth
preparation should encompass necessary reduction relative to
tooth position and the requirements of the restorative material.
The abutment teeth (#13, #14) for zirconium restorations were
prepared. The finish line was a uniform deep chamfer (or could
be a marginal shoulder) of depth 0.8 to 1 mm, allowing a slight
subgingival marginal location of approximately 0.5 mm. Internal
angles should be rounded  (Figure 2).
After the retraction cord was inserted, a simultaneous double
mixed impression was taken using a silicon impression material
(light and heavy silicon) (Figure 3). A temporary restoration was
made directly on the prepared teeth with composite resin. The
master cast was obtained. Models were scanned with an optic
scanner and the framework was designed and milled by CAD/CAM
At the initial trial insertion, different points were checked
including adequate seating of the prosthesis, marginal fit, and
pontic shape. Then, the shade was defined and recorded. The
framework was coated manually with a covering feldspathic
ceramic. The occlusion (static and dynamic occlusion, the canine
guidance) and esthetics were checked intra-orally. After ceramic
glazing, the prosthesis was cemented with glass ionmer cement.
Oral hygiene instruction and regular check-up were administered.
In the recall check-ups, no complications were observed, and the
patient was satisfied with her prosthesis (Figure 5).
Loss of teeth can have esthetic, functional, psychological, and
social impacts on the life of individuals. This explains the necessity
for prosthetic rehabilitation to enhance quality of life . Implant
supported single crown restoration is often the most preferable
treatment modality to replace an extracted upper premolar due to
its non-invasive approach, aesthetic outcome, function restoration,
stability and high survival rate [10,11].
However, a Single-tooth implant in the posterior maxilla
is complicated by reduced bone volume. Moreover, sinus floor
elevation is frequently needed to overcome the lack of sufficient
jaw bone dimensions. But the chronic sinusitis of our patient
counters this procedure. Thus, the clinical disability to create
sufficient bone to house the implant has called for an alternative
conventional treatment which is Fixed Dental Prosthesis (FDPs).
Traditionally, metal based restorations for fixed dental
prostheses were considered as the gold standard for years in
prosthetic dentistry especially, that their long term follow up
studies have proven their good mechanical properties, their
high survival rates and their clinically acceptable quality of their
marginal adaptation [12,13]. However, the first disadvantage of
these prostheses is the luck of esthetics due to the metal substrate
which has to be masked with the opaque porcelain . In addition,
metal-based prostheses may possibly cause negative reactions .
The high aesthetic requirement of the patient ultimately aimed at
using free metal fixed partial dentures certainly that the aesthetic
result of metal-ceramic restorations are significantly limited due
to the absence of translucency caused by the underlying metal
grayish shade and the gum coloration due to the metal corrosion
Furthermore, all ceramic FDPs as part of restorative materials
fulfill perfectly the need for aesthetic and mimic perfectly the
natural teeth. But, in the other hand, all ceramic frameworks
have low mechanical stability which limited their indication. And,
as a compromise between an excellent aesthetic rendering and
mechanical strength and toughness, high strength yttrium-oxide
partially stabilized zirconia (Y-PSZ) has been used as a framework
for bilayered 3 unit FDPs .
Zirconium-dioxide exhibited a flexural strength of 900– 1200
MPa and fracture toughness rated from 5 to 10MP am1/2. Its
mechanical strength is up to three-times better than conventional
all ceramics . Compared to other ceramics, zirconia framework
offers another gain such as the reduction in the layer thickness
which provides for the veneer ceramic the sufficient space to
achieve the desired color .
Moreover, the explanation for such better qualities of this
‘ceramic steel’  result in the way zirconia framework behaves
under applied stress. In fact, in the area of a propagating crack,
the stress induces a phase transformation. This transformation
causes constriction of crack and hardening of the material .
The mechanical properties of the zirconia framework have been
optimized by respecting their clinical recommendations. Indeed,
studies have proved that predominantly short span FDPs have
more survival rate comparing to long span FDPs which are related
most frequently to technical problems . Also, in order to avoid
fracture risk, usually located in the area between the retainer and
pontic, the connector dimension was adjusted of 9mm2 which is
recommended for 3 units FDPs .
Despite the high fracture resistance of zirconia frameworks,
chipping of the veneered porcelain has been noted as a problem in
zirconia-based all-ceramic restorations . To solve the chipping
problem, it was suggested that monolithic translucent TZP offered
higher fracture strength than bilayer veneered zirconia .
However, the prevalence of major and minor chipping is difficult
to exactly confirm . In addition, the survival percentage of
zirconia based prostheses is very good, since the majorities of the
veneer fractures are minor ones and do not weaken the esthetic
and functional outcomes of the restoration .
Add to that, from aesthetic point of view, zirconia has a white
opaque color which needs masking by veneering it with a more
translucent and aesthetic porcelain to enhance a satisfactory
aesthetic outcome for the demanding patient .
To meet the demand of today’s patients, dental prostheses must
take in consideration many properties, including biocompatibility,
esthetics, abrasion resistance, color stability and high-strength.
Regarding his clinical outcome zirconia was chosen as framework
material for all- ceramic FPD for this patient. Many developments
were undertaken since the introduction of zirconia, but others
improvements are wished to make it become the gold standard in