1. By- Dr. Dipanjan Das

2. CONTENTS
• Introduction
• Evolution of the implant material
• Properties of zirconia implant
 Chemical composition, structure, and phases of zirconia implants
 Physical and mechanical properties
 Aesthetics and optical properties
 Osseointegration
 Surface roughness
 Biocompatibility
 Soft tissue response to zirconia implants
 Bacterial colonization around zirconia implants
• Advantages of zirconia implants over
titanium implants
• One-piece and two-piece implants
• Future perspectives with zirconia
implants
• Conclusions

3. Introduction
• In order to replace the missing teeth, oral implants can be considered a preferred option.
• This procedure was first proposed by Brånemark in the 1960s.
• Implants with good biocompatibility, sufficient corrosion resistence and toughness can be
categorized as ideal implants.
• Other ideal properties can be their great strength and resistance to fracture and wear.
• The biological responses of dental implants as well as their chemical composition are the main
properties that are significant in the categorization of these materials.

4. • Currently titanium and titanium alloys are most widely used as
dental implants due to their excellent biocompatibility, good
mechanical properties, and long term follow-up in clinical
success.
• When exposed to air, titanium immediately develops a stable
oxide layer. which forms the basis of its biocompatibility.
• Various modifications in the structure, composition, and design
of titanium implants have been made to enhance its physical,
mechanical and optical properties.
Fig.- Titanium Implant

5. • Despite decades of titanium (Ti) as the gold standard in oral implantology, the search for
alternatives has been growing, because of its disadvantages.
1. The principal disadvantage of titanium is its dark grayish color, which often is visible through
the peri-implant mucosa, therefore impairing esthetic outcomes, especially in the anterior region
where the gingival tissue is considerably thin.
2. some patients could develop clinical signs of hypersensitivity to titanium. The prevalence of
titanium allergy was estimated at 0.6%
3. Some studies have also reported of galvanic reaction that occurs after it comes in contact with
saliva and fluoride.
4. Some studies also reported debated contribution of Ti to peri-implantitis development.
Inflammatory response and bone resorption were found to be induced due to titanium particles.
Apratim A, Eachempati P, Salian KK, Singh V, Chhabra S, Shah S. Zirconia in dental implantology: A review. Journal of International Society of Preventive &
Community Dentistry. 2015 May;5(3):147.

6. • The high esthetic standards demanded nowadays, accompanied
by fears of sensitivity to titanium, has led to the growing
demand for metal-free restorations. Consequently, ceramic
materials were proposed as potential surrogates.
• Zirconia, tetragonal zirconia polycrystal (TZP) in particular,
gained increasing importance due to their mechanical, esthetic
and biocompatible performance for dental implants.
• It is reported that zirconia implants are a promising alternative
to Ti with comparable osseointegration, a superior soft-tissue
response in short-term outcomes.
Fig.- Zirconia implant

7. Evolution of the implant material
• The first generation of ceramic implants was made of aluminum oxide.
• Several systems of aluminum oxide implants were produced, such as Cerasand (Incermed,
Lausanne, Switzerland) and Tubingen implant (Frialit I; Friadent, Mannheim, € Germany).
• Single-crystal alumina implants, such as Bioceram (Kyocera, Kyoto, Japan), have also been
fabricated.
• Aluminum oxide implants can be osseointegrated but their biomechanical properties, as reflected
by fracture toughness, are unsatisfactory.
• Consequently, aluminum oxide implants were withdrawn from the market in the early 1990s.
Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000. 2017 Feb;73(1):241-58.

8. • Zirconium dioxide (zirconia) ceramics with improved properties have been introduced as an
alternative material to Aluminium oxide.
• They were first used for the fabrication of crowns and implant abutments.
• Currently, tetragonal zirconia polycrystal, particularly 3 mol% yttrium oxide (yttria) -stabilized
zirconia, is the ceramic of choice for dental implants.

9. Properties of zirconia implant
• Zirconia implant is made from a lustrous, grey-white, strong transition
metal named Zirconium (Symbol Zr).
• It is a crystalline dioxide of zirconium (ZrO2).
• Jons Jakob Berzelius in 1824 was the first to isolate zirconium in an impure
form.
• The first research paper on the use of ZrO2 as a biomaterial was published
by Helmer and Driskel in 1969.
• The white, opaque color of zirconia, along with its good biocompatibility
and low affinity to bacterial plaque, make it a material of interest in
biomedical sciences.
Fig.- Zirconium
Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000. 2017 Feb;73(1):241-58.

10. • Zirconia also exhibits several promising physical and mechanical properties.
• Initially, zirconia was used in various orthopedic surgical procedures for manufacturing ball heads for total
hip replacements, artificial hips, finger and acoustic implants prosthesis.
• In the early 1990s, zirconia was introduced to dentistry and has been made widely available through the
computer-aided design/computer-aided manufacturing (CAD/CAM) technology.
• The successful use of zirconia ceramics for the fabrication of tooth-supported restorations has encouraged
clinicians to extend its application for implant-supported restorations.

11. Chemical composition, structure, and phases of zirconia implants
• The pure form of Zirconia occurs in two major forms:
(a) the crystalline zirconia which is soft, white, and ductile,
(b) the amorphous form which is bluish-black powder in nature.
• The powder form of Zirconia is refined and subsequently treated synthetically at high temperatures to yield
optically translucent form of crystalline zirconia.
• After purification, the powder form of zirconium is filled into malleable dies and processed under high
pressure (2000–4000 bar) and temperature molds to form homogenous implants of exact dimension.
Sivaraman K, Chopra A, Narayan AI, Balakrishnan D. Is zirconia a viable alternative to titanium for oral implant? A critical review. Journal of Prosthodontic Research.
2018;62(2):121-33.

12. • Three crystalline phases occur in zirconia implants.
• Pure zirconia is monoclinic (m), under ambient conditions.
• With increasing temperature, the material transforms to a tetragonal crystal structure (t) at ∼1170
°C. and
• Then to a cubic crystal structure (c), followed by a fluorite structure at ∼2370 °C with melting at
2716 °C.

13. • The ZrO2 ceramic shows a hysteretic, martensitic transformation during the heating and cooling
processes, while its reversible transformation occurs at ∼950 °C upon cooling.
• Pure zirconia along with various stabilizing oxides such as CaO, MgO, Y2O3 or CeO2 allows the
retention of the tetragonal structure at room temperature. Therefore, it controls stress-induced
transformations.
• This martensitic-like phase transformation toughening significantly increases the crack resistance,
fracture toughness, and longevity of zirconia endosseous implant.
Gautam C, Joyner J, Gautam A, Rao J, Vajtai R. Zirconia based dental ceramics: structure, mechanical properties, biocompatibility and applications. Dalton transactions.
2016;45(48):19194-215.

14. • Other variants of zirconia implants include 12Ce-TZP (Ceria-stabilized zirconia) and ATZ
(Alumina toughened Zirconia).
• Alumina has also been added to Yttria stabilized-tetragonal Zirconia polycrystal (Y-TZP) in low
quantities (0.25 wt%) to yield tetragonal zirconia polycrystal with alumina (TZP-A) with significant
improvement in the durability and stability of zirconia crystals under high temperatures and humid
environment.
• Studies have shown that implants without alumina when exposed to the artificial mouth have a
survival rate of 50%, whereas implants with alumina have a survival rate of 87–100%.

15. Physical and mechanical properties of zirconia implants
• The mechanical and physical properties of zirconia implants depend upon:
Its composition, nature of crystals, metastable polymorphic structure, ratio of the monoclinic to
tetragonal phase, percentage of stabilizing metal oxide, ageing process, macro and microdesign of the
implant, nature of the finish line on the implant abutment, characteristics of implant abutment, and
amount of occlusal load.
Apratim A, Eachempati P, Salian KK, Singh V, Chhabra S, Shah S. Zirconia in dental implantology: A review. Journal of International Society of Preventive &
Community Dentistry. 2015 May;5(3):147.

16. • Yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) materials exhibit superior corrosion
and wear resistance, as well as a high flexural strength (800–1000 MPa) compared to other dental
ceramics.
• It was also found that flexural strength of zirconia increases by mechanical modification of its
surface.
• When the compressive strength of blade type of zirconia implants was tested, it was found to be
adequate in occlusion.
• Fracture strength (512.9 N) of unloaded zirconia was found to be more than the fracture strength
(401.7 N) of loaded zirconia.

17. • It was also found that the implant preparation and cyclic loading decrease the fracture strength of
one-piece zirconia implants, but these values were still within clinically acceptable limits to
withstand average occlusal forces even after an extended interval of artificial loading.
• Due to severe environmental conditions of moisture and stress, the resulting zirconia may transform
more aggressively to the monoclinic phase with micro crack formation .
-This mechanical property degradation in zirconia is known as “aging” of the material.
• This can lead to:
 Increase in the water penetration and resultant corrosion
 Crack propagation
 Surface deterioration
 Phase destabilization and
 Decreased resistance to load.

18. • The aging process depends on various factors like porosity, residual stresses, grain size, and the
content of stabilizer.
• It was found that decrease in grain size and increase in stabilizing oxide content reduce the
transformation rate.
• Aging is accelerated due to changes in processing technique and can be avoided by more
accurate processing.
• Some in vitro studies have found that the aging reduces the mechanical properties of zirconia,
even though within clinical acceptable limits, in simulated dental treatment conditions.

19. Aesthetics and optical properties of zirconia
• An important advantage of zirconia implant is in relation to its excellent aesthetics.
• The optical behavior of zirconia varies with its composition, crystal size, grain distribution and
methods of machining.
• The enhanced aesthetics of zirconia is attributed its ability to mask dark substrates with good
opacity in the visible and infrared spectrum and controlled translucency.
• The masking ability is due to its grain size being greater than the length of light, high refractive
index, low absorption coefficient, high density with low residual porosity.
Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000. 2017 Feb;73(1):241-58.

20. • Unlike polycrystalline alumina, single crystal alumina is more glassy and translucent in
appearance. Alloying Y-TZP with alumina cause a slight reduction in its translucency.
• “translucent” zirconia blocks are made from Y-TZP and “opaque” zirconia blanks are made up
of TZP-A.
• Therefore, 3Y-TZP blocks of zirconia implants that are pure white in color should be adequately
masked with translucent ceramics to simulate the color of natural teeth.

21. Osseointegration of zirconia implants
• One of the most important criteria for the success of implant treatment is osseointegration.
• Bone apposition takes place on different types of implant surfaces and depends on surface
roughness of the implant.
• Studies have shown that zirconia coating on the surface of titanium implants favours bone
apposition, which was found to be more than that of titanium implants with no coating.

22. • Akagawa et al., in their study, found no
significant difference in bone implant contact
(BIC) between the loaded and unloaded
zirconia implants.
• Another study which examined the role of
osseointegration around one-stage zirconia
screw implant under various conditions for
loading showed no difference in bone contact
ratio among the single freestanding, connected
freestanding, and implant-tooth supports of
partially stabilized zirconia implants.
Fig.- Osseointegration of zirconia and titanium
implants
• Akagawa Y, Ichikawa Y, Nikai H, Tsuru H. Interface histology of unloaded and
early loaded partially stabilized zirconia endosseous implant in initial bone
healing. J Prosthet Dent 1993;69:599-604
• Akagawa Y, Hosokawa R, Sato Y, Kamayama K. Comparison between
freestanding and tooth-connected partially stabilized zirconia implants after two
years’ function in monkeys: A clinical and histologic study. J Prosthet Dent
1998;80:551-8

23. • When BIC of zirconia implants was compared with that of titanium and alumina, there was no
statistical difference between the BIC of all three types of implants.
-Relatively bone healing around zirconia implants was found to be more than around titanium
implants.
• Similar rate of bone apposition on zirconia and surface-modified titanium implant surfaces during
early healing was found when a histological examination of early bone apposition around zirconia
dental implants at 2 and 4 weeks after insertion was compared to that of surface-modified titanium
implants.
• There was also no difference in osseointegration between acid-etched zirconia implants and
acid-etched titanium implants.

24. Surface roughness of zirconia implants
• While direct bone apposition can occur on different types of surfaces, it has been demonstrated that
a certain degree of surface roughness is beneficial in accelerating bone apposition to the implant
surface.
• Various surface modifications have been developed to enhance the osseointegration of zirconia
implants. Such as:
 Acid etched Zirconia
 sandblasted Zirconia
 plasma sprayed
 anodized,
 Machined
 chemically modified
(plasma-anodized)
 coated (calcium phosphate,
or collagen type I with
chondroitin sulphate)
 nanotechnology surface
modified (Calcium
phosphate nano layer)

25. Fig.- Various surface modifications of zirconia implants

26. • These surface modifications at microscopic level enhance osseointegration by increasing the
roughness, wettability and expression of integrin’s alpha5 and beta1 mediated osteoblast-gene
expression and osteoblast-like cells adhesion, spreading and migration on the zirconia implant
substrates.
• When osteoblast differentiation on two different zirconia surfaces (sandblasted with alumina
particles or SLA in a mixture of hydrofluoric acid and sulfuric acid) was compared with standard
titanium surface (sandblasted and acid-etched), zirconia substrates showed better osteoblastic
adhesion and proliferation compared with titanium.(Hempel et al.)
Hempel U, Hefti T, Kalbacova M, Wolf‐Brandstetter C, Dieter P, Schlottig F. Response of osteoblast‐like SAOS‐2 cells to zirconia ceramics with different surface
topographies. Clinical oral implants research. 2010 Feb;21(2):174-81.

27. • Bachle et al. evaluated the cell proliferation on machined, sandblasted, and Sandblasted, large grit,
acid etched (SLA) zirconia surfaces and found that airborne particle abrasion and acid-etching
increased the surface roughness of zirconia implants with enhanced cell proliferation compared to
machined zirconia implants.
• Moreover, sandblasting zirconia particles on implant surface significantly improves the peri-implant
osteogenesis compared to machined titanium surfaces.
Bächle M, Butz F, Hübner U, Bakalinis E, Kohal RJ. Behavior of CAL72 osteoblast‐like cells cultured on zirconia ceramics with different surface topographies. Clinical
oral implants research. 2007 Feb;18(1):53-9.

28. • Bioactive glass as a surface coating material has also been tried for zirconia implants with promising
results like enhancement of the early osseointegration rate as compared to non-coated implants.
-Bioactive glass coated Zirconia implants is useful in geriatric patients with poor bone quality or
osteoporotic bone.
• High hardness of the zirconia implants makes the process of surface roughening very difficult. So,
recently, laser has been used to engrave a pattern on the zirconia surface.
• A scanning electron microscopic (SEM) study done to find the influence of (Er: YAG), (CO2 ), and
diode laser irradiation on the surface properties of polished zirconia implants demonstrated that
diode and Er: YAG lasers did not cause any visible surface alterations. However, the CO2 laser
produced distinct surface alterations to zirconia.
Stübinger S, Homann F, Etter C, Miskiewicz M, Wieland M, Sader R. Effect of Er: YAG, CO (2) and diode laser irradiation on surface properties of zirconia endosseous
dental implants. Lasers Surg Med 2008;40:223-8.

29. Biocompatibility of zirconia implants
• Various in vitro tests were conducted on osteoblasts, fibroblasts, lymphocytes, monocytes, and macrophages to
test the biocompatibility of zirconia.
• It was observed that zirconia had no cytotoxic effect on fibroblasts, osteoblasts and made the cells capable of
elaborating the extracellular matrix by synthesizing various essential and structural proteins.
• Zirconia does not induce pseudo-teratogenic effect, which makes it biocompatible.
• Laser-modified zirconia showed better adhesion to osteoblasts due to the better wettability characteristics.

30. • Both powder and particles of zirconia tested in vitro on different cell lines (human and murine) of
lymphocytes, monocytes, or macrophages did not induce high cytotoxicity or inflammation.
• Biocompatibility tests were also conducted in vivo for zirconia, and it was found that when it was
implanted in the soft tissue, it became encapsulated by a thin layer of fibrous tissue similar to that
seen in the case of alumina.
• Also, there was no cytotoxicity in the soft tissue in relation to wear products of zirconia.

31. • Zirconia was also found to be biocompatible to hard tissue when tested in vivo according to the
findings of a study which inserted pellets of stabilized zirconia with 6% Y2 O3 into the femur
of monkeys.
• In the study by Kohal et al., it was found that cell proliferation around zirconia was comparable
to titanium, but surface modification of zirconia did not show improvement in osseointegration.
Kohal RJ, Bächle M, Att W, Chaar S, Altmann B, Renz A, et al. Osteoblast and bone tissue response to surface modified zirconia and titanium implant materials.
Dent Mater 2013;29:763-76.

32. Soft tissue response to zirconia implants
• The bio-inert properties of zirconia help in rapid proliferation of the human
gingival fibroblasts over the implant surface and formation of a good mucosal
barrier.
• However, various factors such as surface characteristics and design, nature of
implant material and degree of roughness influence the nature and amount of
the mucosal seal around zirconia implants.
• A smooth implant surface promotes a good soft tissue seal in comparison to a
rough implant surface.
Sivaraman K, Chopra A, Narayan AI, Balakrishnan D. Is zirconia a viable alternative to titanium for oral implant? A critical review. Journal of Prosthodontic Research.
2018;62(2):121-33.

33. • Various differences have been observed in the periimplant mucosa around zirconia implants as
compared to titanium. The expression of chemical mediators such as integrin alpha2, integrin
alpha5 and type I collagen are found to be more up-regulated on smooth zirconia implants as
compared to titanium.
• However, the pattern of connective tissue adhesion and transgingival collar around zirconia
implants is similar to that seen around machined titanium surface.
• The color of the periimplant mucosa, the amount of bleeding on probing and probing depth is
similar around zirconia implants as compared to titanium implants

34. • The presence of a long junctional epithelium with a high density of collagen fibers around zirconia
implants provides a better soft tissue integration with less ingress of the bacteria and reduced
inflammatory infiltration as compared to titanium implants.
• A low inflammatory response around zirconia implant is attributed to increased release of various
angiogenic factors and anti-inflammatory cytokines as compared to Titanium.
• The inflammatory response is more around titanium implant with higher microvessel density,
vascular endothelial growth factor expression, expression of nitric oxide synthase as compared to
zirconia

35. Bacterial colonization around zirconia implants
• Various microbiological and in-vivo studies have reported a reduced number of cocci and rods around
zirconia implant as compared to titanium implants.
• These bioinert properties enhance perio-integration around zirconium implants and in turn prevent the
development of peri-implant bone resorption and peri-implant soft inflammation.
• Nascimento et al. in a randomized crossover clinical trial identified and quantified the microbial species
in 24-h biofilms on different implant materials (machined titanium; cast and polished titanium; and
zirconia) using DNA checkerboard hybridization technique.
Nascimento CD, Pita MS, Fernandes FHNC, Pedrazzi V, de Albuquerque Junior RF, Ribeiro RF. Bacterial adhesion on the titanium and zirconia abutment surfaces. Clin
Oral Implants Res 2014;25:337–43

36. • The results showed that cast and polished titanium showed higher proportions of rods and
filamentous bacteria and fewer cocci compared with machined titanium and zirconia.
• In the cast and polished titanium group, Aggregatibacter actinomycetemcomitans and
Porphyromonas gingivalis were detected in 100% and 95% of the samples respectively.
• In addition, in Zirconia group, S. mutans was recorded in 58.34% of samples, while Streptococcus
mitis and Staphylococcus pasteuri were recovered from only 54.17% of samples

38. Advantages of zirconia implants over titanium implants
• An important advantage of zirconia implant over titanium is in relation to its
excellent aesthetics. Zirconium implants have an obvious esthetic advantage
over titanium implants being “pure white”, making them indistinguishable
from natural teeth.
• Although Compared to titanium, its osseointegration is inferior, relatively bone
healing around zirconia implants was found to be more than around titanium
implants .
• When peri-implant tissue compatibility is the subject of discussion, the
presence of a long junctional epithelium with a high density of collagen fibers
around zirconia implants provides a better soft-tissue integration with less
ingress of the bacteria and reduced inflammatory infiltration as compared to
titanium implants.

39. • Zirconia implant has also shown to inhibit bacterial adhesion and biofilm formation on its surface
because of its hydrophobicity, bio-inert properties, optimal smoothness, reduced surface free
energy and surface wettability.
• Apart from low bacterial colonization, a low inflammatory response around zirconia implant is
attributed to increased release of various angiogenic factors and anti-inflammatory cytokines as
compared to Titanium.
• The additional advantages of zirconia are:
 No evidence for mutagenic or carcinogenic effects.
 Zirconia has more biocompatibility as compared to titanium, as the latter produces corrosion
products at the implant site.

40. One-piece and two-piece implants
• Currently, the majority of zirconia implants produced are one-piece implants .Such systems have
several limitations.
1. The surgical placement of the implant may not always meet the prosthodontic requirements, and
angled abutments to correct misalignment are unavailable.
2. Secondary corrections of the shape by grinding must be avoided as this severely affects the
fracture strength of zirconia
3. Moreover, single-piece implants are immediately exposed to forces from the tongue or as a result
of mastication.
Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000. 2017 Feb;73(1):241-58.

41. 4. the correct vertical positioning of the implant may be more of a challenge.
5. In the esthetic zone, implants are often inserted deeper to avoid visibility of the crown margin.
Increases the risk for inadvertently leaving excess luting cement
Induces local infection, which occasionally instigates substantial tissue damage
• Concerning one-piece implants, two patterns of fracture were identified in an in vitro study.
 When the implants were not prepared, the fracture line was horizontal, at the limit of the embedding
resin.
 When the implants were modified by grinding, the fracture was vertically parallel to the long axis.

42. • At present, only a few ceramic systems offer two-piece implants.
 In two clinical studies, prefabricated zirconia abutments were
cemented on implants using a dual-cure resin cement.
 Another method, in which a modifiable glass-fiber abutment was
fixed adhesively to the implant.
• Two-piece systems are preferable to the one-piece implant when
initial stability is not optimized at implant placement. Bone
augmentation procedures can also be used with two-piece system.
• The challenge of this design remains in the quality and the
strength of the connection between the abutment and the implant.
Fig.- One-piece and two-piece implants

43. • An in vitro experiment tested the fracture resistance of two-piece zirconia and titanium implant prototypes
under forces representative of a period of 5 years of clinical loading. Thirty-two zirconia implants were used.
When the implants were artificially loaded, the authors measured fracture strength of 277 N in the zirconia
group and 165 N in the titanium group.(Kohal et al.)
• When two-piece implants were compare with one-piece implants in an animal study in dogs, a higher fracture
rate found for one-piece zirconia implants than for two-piece implants. Of the seven fractured implants, six
were one-piece. The failures appeared during the period between the healing phase and 6 months after loading.
• Kohal RJ, Finke HC, Klaus G. Stability of prototype twopiece zirconia and titanium implants after artificial aging: an In Vitro pilot study. Clin Implant Dent Relat Res
2009: 11: 323–329
• Thoma DS, Benic GI, Munoz F, Kohal R, Sanz Martin I, ~ Cantalapiedra AG, Hammerle CH, Jung RE. Marginal € bone-level alterations of loaded zirconia and titanium
dental implants: an experimental study in the dog mandible. Clin Oral Implants Res 2016: 27: 412–42

44. Future perspectives with zirconia implants
• In a sense, a novel approach should be taken when dealing with zirconia.
• Protocols used to design, manufacture and test titanium implants cannot simply be translated to
produce and evaluate zirconia implants.
• New methods are required considering the biomechanical properties of zirconia in general, and
aging in particular.
Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000. 2017 Feb;73(1):241-58.

45. • The stability of zirconia can be compromised by very small defects acquired during or after
fabrication, and osseointegration depends on specific details in the chemical composition of the
material, as well as texture and purity of the surface.
-Standardization of the manufacturing processes and quality control of the end products is therefore
essential.
• Different approaches are being studied to improve the physical and chemical properties of the
material and new zirconia composite ceramics developed.

46. • One is known as ceria partially stabilized zirconia/alumina nanostructured composite or NANOZR.
-This composite exhibits a flexural strength twice that of yttria-stabilized tetragonal zirconia
polycrystal and greater fracture toughness.
-In addition, it is less subject to low-temperature degradation.
• In vitro experiments demonstrate promising results in terms of cell adhesion, spreading and
differentiation into bone-forming cells.
• An animal study presented similar histological and histomorphometric results for titanium, yttria-
stabilized tetragonal zirconia polycrystal and NANOZR.
Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000. 2017 Feb;73(1):241-58.

47. • Other modifications on zirconia implants -Yttria-stabilized tetragonal zirconia polycrystal was toughened
by the addition of 20 weight per cent alumina (alumina-toughened zirconia).
• Laboratory experiments have evaluated the fracture strength of alumina-toughened zirconia implant
prototypes under different loading procedures.
-They reported no implant fracture during loading and significantly higher mean fracture strength for alumina-
toughened zirconia implants (1,064–1,734 N) than for tetragonal zirconia polycrystal implants (516–607 N).
• When the abutment was ground, the fracture strength was reduced but still showed better values than non-
prepared tetragonal zirconia polycrystal implants.
Kohal RJ, Wolkewitz M, Mueller C. Alumina-reinforced zirconia implants: survival rate and fracture strength in a masticatory simulation trial. Clin Oral Implants
Res 2010: 21: 1345–1352.

48. Conclusions
• Limited amount of research on zirconia proves that zirconia is biocompatible with the surrounding tissues.
• Compared to titanium, its osseointegration is inferior and shows improvement after surface modification.
• Strength of zirconia is good, but comparatively lesser than that of titanium.
• Zirconia is Osseoconductive as reported in some studies and has also shown favorable interaction with the
soft tissue.
• It has been found that zirconia reduces plaque formation on the implant surface, which leads to good healing
and successful implant treatment.
• Most of the studies on zirconia implants are short-term studies and evidence of success in long-term clinical
trials is lacking. More research is needed on zirconia dental implants before we could use it for frequent
treatment needs, as compared to titanium implants.

49. References
• Apratim A, Eachempati P, Salian KK, Singh V, Chhabra S, Shah S. Zirconia in dental implantology: A review. Journal of
International Society of Preventive & Community Dentistry. 2015 May;5(3):147.
• Cionca N, Hashim D, Mombelli A. Zirconia dental implants: where are we now, and where are we heading?. Periodontology 2000.
2017 Feb;73(1):241-58.
• Sivaraman K, Chopra A, Narayan AI, Balakrishnan D. Is zirconia a viable alternative to titanium for oral implant? A critical review.
Journal of Prosthodontic Research. 2018;62(2):121-33.
• Gautam C, Joyner J, Gautam A, Rao J, Vajtai R. Zirconia based dental ceramics: structure, mechanical properties, biocompatibility
and applications. Dalton transactions. 2016;45(48):19194-215.
• Hempel U, Hefti T, Kalbacova M, Wolf‐Brandstetter C, Dieter P, Schlottig F. Response of osteoblast‐like SAOS‐2 cells to zirconia
ceramics with different surface topographies. Clinical oral implants research. 2010 Feb;21(2):174-81.
• Bächle M, Butz F, Hübner U, Bakalinis E, Kohal RJ. Behavior of CAL72 osteoblast‐like cells cultured on zirconia ceramics with
different surface topographies. Clinical oral implants research. 2007 Feb;18(1):53-9.
• Stübinger S, Homann F, Etter C, Miskiewicz M, Wieland M, Sader R. Effect of Er: YAG, CO (2) and diode laser irradiation on
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52. Thank you