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Shock Absorption Capacity of Restorative Materials for Dental Implant Prostheses: An In Vitro Study


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Purpose: To measure the vertical occlusal forces transmitted through crowns made of different restorative materials onto simulated peri-implant bone. Materials and methods: The study was conducted using a masticatory robot that is able to reproduce the mandibular movements and forces exerted during mastication. During robot mastication, the forces transmitted onto the simulated peri-implant bone were recorded using nine different restorative materials for the simulated single crown: zirconia, two glass-ceramics, a gold alloy, three composite resins, and two acrylic resins. Three identical sample crowns for each material were used. Each crown was placed under 100 masticatory cycles, occluding with the flat upper surface of the robot to evaluate the vertical forces transmitted. Two-way analysis of variance was used. Alpha was set at .05. Results: The statistical evaluation of the force peaks recorded on the vertical z-axis showed mean values of 641.8 N for zirconia; 484.5 N and 344.5 N, respectively, for the two glass-ceramics; 344.8 N for gold alloy; 293.6 N, 236 N, and 187.4 N, respectively, for the three composite resins; and 39.3 N and 28.3 N, respectively, for the two acrylic resins. Significant differences were found between materials (P < .0001), except for the comparison between gold alloy and one of the glass-ceramics. Conclusion: Composite and above all acrylic resin crowns were more able to absorb shock from occlusal forces than crowns made of zirconia, ceramic material, or gold alloy.
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Volume 26, Number 6, 2013 549
Implant dentistry has become an increasingly effective
method for correcting edentulism, either partially or
completely. Implant treatments exhibit an overall excel-
lent clinical success rate in the long term.1–4 Despite its
rare occurrence, the reasons for peri-implant bone loss
and implant failure in some patients are not completely
understood. Multifactorial aspects (general health,
bone quality and quantity, surgical procedure, implant
characteristics, parafunctional habits, occlusal over-
loading, medications, bacterial insult, etc) potentially
induce peri-implant bone damage. However, the role
of some of these aspects in reaching and maintaining
osseointegration is controversial.5 Several authors con-
sider occlusal load a crucial factor affecting the dental
implant healing phase and the long-term survival and
success of dental implants.6 –12
In teeth, a semi-elastic connection between the
tooth and bone exists (periodontal tissue), whereas
in implants, a direct and relatively rigid connection
between the bone and implant is achieved if healing
without complications has taken place.13,14 Therefore,
a direct transmission of forces on the peri-implant
bone without any shock-absorbing element is conse-
quent to implant loading.14 It can usually be achieved
by the adaptation capacity of peri-implant bone ar-
chitecture toward changing load conditions.15,16
According to Frost,15,16 within the range of a physi-
ologic loading, bone undergoes its physiologic turn-
over. In mild overloading, below bone’s microdamage
threshold, modeling drifts can begin adding to and/
or reshaping bone. But in the case of a pathologic
overload, bone fractures and bone resorption may oc-
cur.15,16 For these reasons, it appears to be impor tant
to control the forces transmitted on the bone-implant
interface. However, the amount of load defined as
overload has not been quantified because the range
of host physiologic adaptability varies. Overload can
be considered the amount of force that overextends
the host sites adaptation potential.
Assistant Professor, Department of Fixed and Implant
Prosthodontics, University of Genoa, Genoa, Italy.
Lecturer, Department of Prosthodontics, University of Turin,
Turi n , I ta ly.
Lecturer, Department of Health Sciences, Section of Biostatistics,
University of Genoa, Genoa, Italy.
Chief and Professor, Department of Fixed and Implant
Prosthodontics, University of Genoa, Genoa, Italy.
Correspondence to: Dr Maria Menini, Department of
Prosthodontics (Pad. 4), Ospedale S. Martino,
L. Rosanna Benzi 10, 16132 Genova, Italy.
Fax: + 39 0103537402. Email:
©2013 by Quintessence Publishing Co Inc.
Shock Absorption Capacity of Restorative Materials for
Dental Implant Prostheses: An In Vitro Study
Maria Menini, DDS, PhDa/Enrico Conserva, DDSa/ Tiziano Tealdo, DDSa/Marco Bevilacqua, DDSa/
Francesco Pera, DDS, PhDb/Alessio Signori, MScc/Paolo Pera, MD, DDS, PhDd
Purpose: To measure the vertical occlusal forces transmitted through crowns made of
different restorative materials onto simulated peri-implant bone. Materials and Methods:
The study was conducted using a masticatory robot that is able to reproduce the
mandibular movements and forces exerted during mastication. During robot mastication,
the forces transmitted onto the simulated peri-implant bone were recorded using nine
different restorative materials for the simulated single crown: zirconia, two glass-ceramics, a
gold alloy, three composite resins, and two acrylic resins. Three identical sample crowns for
each material were used. Each crown was placed under 100 masticatory cycles, occluding
with the flat upper surface of the robot to evaluate the vertical forces transmitted. Two-way
analysis of variance was used. Alpha was set at .05. Results: The statistical evaluation of
the force peaks recorded on the vertical z-axis showed mean values of 641.8 N for zirconia;
484.5 N and 344.5 N, respectively, for the two glass-ceramics; 344.8 N for gold alloy;
293.6 N, 236 N, and 187.4 N, respectively, for the three composite resins; and 39.3 N and
28.3 N, respectively, for the two acrylic resins. Significant differences were found between
materials (P < .0001), except for the comparison between gold alloy and one of the
glass-ceramics. Conclusion: Composite and above all acrylic resin crowns were more
able to absorb shock from occlusal forces than crowns made of zirconia, ceramic material,
or gold alloy. Int J Prosthodont 2013;26:549–556. doi: 10.11607/ijp.3241
550 The International Journal of Prosthodontics
Shock Absorption of Restorative Materials
Clinical evidence on the impact of overloading on
peri-implant bone is not available. Only some case re-
ports17–19 and animal studies9,12 , 20 are present. In fact,
clinical trials evaluating overloading are difficult to
design due to ethical reasons. Moreover, it is gener-
ally impossible to identify the reason for peri-implant
bone loss in clinical cases, distinguishing overload-
ing from other potential sources of bone loss. It is the
authors’ opinion that a prudent approach to implant
prosthodontics should be aimed at avoiding the risk
of overloading the implants. In vitro studies21–25 also
demonstrate that off-axial loads increase stress on
the bone-implant interface with respect to axial loads
and may also be responsible for increased resorption
of crestal bone.20
Some authors maintain that the type of material
used for the prosthesis supported by the titanium im-
plant could affect occlusal load.14,26–32 In particular, in
the 1980s, some investigators recommended resilient
occlusal materials such as acrylic resin to reduce the
forces exerted on implants.14,33,34
However, contrasting results on this topic35–38 sug-
gest the need for further investigation. The role of
dental materials in occlusal stress transmission onto
peri-implant bone seems to be especially relevant
over the past few years because of the increasing use
of esthetic but rigid materials, such as glass-ceramic
and zirconia. These materials are reported to have
excellent mechanical and biologic properties,39,40 but
their impact on peri-implant bone and on the whole
masticatory system has not yet been investigated.
The aim of this study was to investigate in vitro the
shock absorption capacity of nine different restor-
ative materials, including both traditional and modern
esthetic materials, using a masticatory robot.
Materials and Methods
A masticatory robot able to simulate human chewing
in vitro was used (Fig 1), reproducing three-dimen-
sionally the masticatory movements and loads ex-
erted during mastication, as described in a previous
The movable part of the robot is composed of a
Stewart platform and simulates the mandible. The
fixed upper part of the robot simulates the maxilla.
A sensor-equipped base is placed on the moving
platform and records the degree of force being trans-
mitted through the three axes (x, y, and z).
The sensor-equipped base supports a pin that
simulates the implant-abutment system (Fig 2a).
The samples to be tested are placed on the pin and
stressed in the various directions during the robot’s
Fig 1 (left) Sensor-equipped masticatory robot.
Fig 2 (below) Pin simulating the implant-abutment system
with a ceramic sample crown. (a) A groove was made on the
pin to match a ridge inside the sample crown, so that the crown
would sit precisely on the pin without any possibility of rotation
or other movement during testing. (b) The sample crown has
been inserted onto the pin.
Volume 26, Number 6, 2013 551
Menini et al
The materials tested were yttrium cation-doped
tetragonal zirconia polycrystals (Procera Zirconia,
Nobel Biocare), a lithium disilicate pressable ceramic
(Empress 2, Ivoclar Vivadent), a low-fusing leucite-
based pressable ceramic (Finesse, Dentsply), a gold
alloy (Ney-Oro CB, Dentsply), a microfilled hybrid
composite resin (Experience, DEI Italia), a microfilled
composite resin (Adoro, Ivoclar Vivadent), a nano-
hybrid composite resin (Signum, Heraeus Kulzer), and
two acrylic resins (Easytemp 2, DEI Italia and Acry
Plus V, Ruthinium) (Table 1).
In total, 27 identical sample crowns were made
(three for each material). The occlusal surfaces were
semispherical in shape (6.5-mm diameter) (Fig 2b).
The main axis of the sample was 11-mm long. The
sample crowns presented a single contact point at the
center of the occlusal surface when occluding with
the flat maxilla of the robot. At this point, the thickness
of the material tested was 5 mm. Each sample was
measured on its main and smaller axes. The material
thickness at the contact point was also measured with
calipers to verify that all crowns were identical.
The specimens tested were chosen at random and
not in a pre-established sequence. Each crown was
placed under 100 chewing cycles with the sample
crown occluding with the flat fixed maxilla of the ro-
bot. The masticatory robot was programmed to follow
a trajectory reproducing human chewing, as described
in the previous paper.26 The masticator traced this
trajectory in all tests described and the movements
were executed independently from generated force.
Vertical loads (kg) transmitted at the simulated
peri-implant bone were recorded using strain gauges
stuck on the sensorized base supporting the simu-
lated implant-abutment system.
With MATLAB 6.1 (MathWorks), the maximum val-
ues of the forces recorded for each masticatory cycle
were highlighted. These values underwent statistical
analysis using SPSS software (version 18.0, IBM). Two-
way analysis of variance (ANOVA) was used to compare
transmitted stresses between the nine materials tested
and across the three sample crowns of each material.
All tests were two-tailed. Alpha was set at .05.
Post hoc comparisons were assessed by means
of the Scheffe test or, alternatively, by means of the
Tamhane test when homogeneity of variances among
materials was not satisfied.
Vertical loads were converted and are found
throughout the paper in Newtons.
The ANOVA found a significant difference between
the forces transmitted using different materials, and
the Scheffe post hoc test was applied. Within the ma-
terials, an internal comparison showed a significant
difference with P < .0001. Only the difference in mean
maximum force between Ney-Oro and Finesse was
not statistically significant (P > .999).
Comparisons within sample crowns made for each
material did not show significant differences, and one
unique mean was reported for each material.
The force transmitted through the simulated im-
plant onto the simulated peri-implant bone by zirco-
nia (mean 641.8 N) was the greatest ( Table 2).
The slope of the curve, representing the force
transmitted onto the peri-implant level, showed that
materials with greater elastic moduli have steeper
peaks compared with other materials, that is, the
maximum force is reached more rapidly.
Table 1 Elastic Moduli of Tested Materials
Material Manufacturer Type of material Elastic modulus (MPa)
Procera Zirconia Nobel Biocare Zirconia 210,000
Empress 2 Ivoclar Vivadent Glass-ceramic 96,000
Ney-Oro CB Dentsply Gold alloy 77,000
Finesse Dentsply Glass-ceramic 70,000
Experience DEI Italia Composite resin 13,000
Adoro Ivoclar Vivadent Composite resin 7,000 ± 500
Signum Heraeus Kulzer Composite resin 3,500
Easytemp 2 DEI Italia Acrylic resin 2,300
AcryPlus V Ruthinium Acrylic resin N/A
N/A = not available.
552 The International Journal of Prosthodontics
Shock Absorption of Restorative Materials
In this investigation, the use of different restorative
materials significantly affected stress transmission on
the simulated peri-implant bone. In fact, more elastic
materials reduced the stress recorded.
The difference in stress transmission between the
gold alloy and one of the two glass-ceramics was the
only difference not statistically significant, presum-
ably because of their similar Young’s moduli (Table 1).
Zirconia and ceramic crowns also showed steeper
peaks of force compared with other materials. These
were considered effects of the different elastic moduli
of the materials tested.
According to Skalak,14 the viscoelastic behavior of
an acrylic resin as occlusal material would be enough
to delay the transmission of force and reduce its peak
compared with materials with greater elastic moduli.
An in vitro study by Gracis et al32 concluded that
the harder and stiffer the material, the higher the
force transmitted onto the implant and the shorter
the rise time. In fact, according to Hooke’s law, the
higher the modulus of elasticity of a material, the less
the material will deform under pressure and the more
likely the force will be transferred through the mate-
rial.41 Conversely, the more resilient the material, the
more easily it will deform under pressure, the longer
the rise time, and the smaller the stress.
However, a review of the literature over the last
20 years demonstrated that many articles refute the
existence of a shock absorption capacity of resilient
dental materials.42–49
Some of these studies have used Instron ma-
chines48 and some have used finite element analysis
(FEA).44,46,47 These studies have several limitations.
They do not accurately reproduce the mandibular
kinematics. Instron machines perform intermittent
movements in only a single plane. They do not repli-
cate the same masticatory cycle that occurs clinically
with mastication.
With regard to FEA, which included a virtual simu-
lation, the validity of the mathematical model is dif-
ficult to estimate objectively, and the assumptions
made in the use of FEA in implant dentistry must be
taken into account when interpreting the results. In
fact, during the modeling process, several simplifica-
tions are necessary (model geometry, material prop-
erties, applied boundary conditions, etc) and greatly
affect the predictive accuracy of FEA.50
An experiment conducted on beagle dogs51 did
not show any clinical, radiographic, or histologic dif-
ferences between peri-implant tissues surrounding
prosthetic restorations made with composite resin
versus those made with ceramic materials. However,
this study did not control the amount of force exerted
onto the implants, and dogs do not replicate human
In vivo studies41,43,49 have measured masticatory
forces transmitted through various restorative mate-
rials in patients without finding significant differences
in the results.
This type of test requires that sensors and connect-
ing wires be applied intraorally, which raises several
concerns. For instance, this type of testing may al-
ter the masticatory cycles of the study participants
and therefore may distort the results. Moreover, the
technique is not conducive to studying humans over
long experimental periods, and the masticatory cycles
are not identical. In addition, it is not possible to di-
rectly measure the forces transmitted onto the bone-
implant interface.
Using the masticatory robot, an attempt was made
to overcome the limitations associated with previ-
ous studies, approximating the three-dimensional
nature of masticatory function by an in vitro model.
The forces were measured by strain gauges attached
to the sensorized base to which the simulated den-
tal implant was screwed; therefore, it was considered
that the forces were recorded at the simulated peri-
implant bone.
Even though non-axial forces seem to be a more
relevant factor for bone maintenance compared with
axial forces, in the present paper, only data regarding
vertical forces have been reported. In fact, previous
papers26,27 showed that the percentage difference
of force using different materials was superimpos-
able on the three axes; data for the three axes were
redundant. For this reason, in the present research,
the sample crowns were left to occlude with a flat
surface and not with the reproduction of the maxilla.
Table 2 Comparison of the Maximum Forces (N)
Transmitted onto the Simulated Peri-implant Bone
Material Mean force (SD)
Difference of force
vs zirconia (%) P
Procera Zirconia 641.8 (6.8)
Empress 2 484.5 (5.5) –24.51
Ney-Oro CB 344.8 (5.7) –46.28
Finesse 344.5 (3.5) –46.32
Experience 293.6 (16.3) –54.25 < .0001
Adoro 236 (4.2) –62.23
Signum 187.4 (6.7) –70.80
Easytemp 2 39.3 (2.3) –93.88
AcryPlus V 28.3 (4.2) –95.59
Volume 26, Number 6, 2013 553
Menini et al
Occluding with a flat surface, forces on the horizontal
plane were near zero and only data recorded on the
vertical axis were considered for statistical analysis.
The present in vitro setup presents several limita-
tions in simulating the clinical situation. Namely, the
moving platform and the upper part of the robot, sim-
ulating the maxilla, are rigid systems that cannot re-
produce the inherent elasticity of human tissues. The
elastic properties of implant, abutment, and screws
were not properly simulated.
Moreover, no attempt was made to simulate the oral
environment in terms of humidity and temperature.
Comparability of the in vitro and in vivo loading
conditions is limited. Therefore, the absolute values of
force recorded at the peri-implant bone in the present
study cannot be directly correlated to the forces that
would be present in vivo.
It should also be noted that the masticatory system
is provided with protective and self-regulatory mecha-
nisms not simulated in the present in vitro setup. In
fact, natural teeth are equipped with periodontal
mechanoreceptors that signal information about tooth
loads and are involved in the control of human jaw
actions aiming at preventing accidental excessive oc-
clusal loads.52 On the other hand, dental implants lack
periodontal receptors. However, a tactile sensibility at
the level of dental implants (so-called osseopercep-
tion) has been demonstrated and could be responsible
for an implant-mediated sensory-motor control.53
Despite the limits of the present in vitro setup in
simulating the oral implant situation, the attempt was
made to eliminate all possible variables involved. The
standardized in vitro system allowed for fabrication
of identical sample crowns that were all submitted to
identical loading conditions.
A previous paper26 demonstrated that the mas-
ticatory robot is able to reproduce, several times
over, identical masticatory cycles. The paper also
confirmed the precision of the machine during data
collection, therefore validating the reliability of the
method. In fact, the small variations found showed
that the tests are also repeatable and effective under
lengthy testing.
The only variable in the system described was the
material from which the crowns were made, which is
mandatory for a reliable comparison of different mate-
rials. The system was designed to make a comparison
between different materials effective and repeatable.
In the present study, a single crown was tested,
demonstrating a shock absorption potential for acryl-
ic resin. However, contrasting results could be found
using multiunit prostheses.41,44,54,55 In fact, stiff pros-
thetic materials are supposed to distribute the stress
more evenly to the abutments and implants. It is the
authors’ opinion that, in multiunit prostheses, a stiff
substructure (ie, gold alloy) rigidly splinting the im-
plants would be the best option to evenly distribute
loads. The shock absorption capacity of more resil-
ient restorative materials could be used at the lev-
el of the occlusal surface in association with a stiff
The present paper evaluates the shock absorption
capacity of nine restorative materials, including gold
alloy and zirconia, which were not tested in previ-
ous studies.26,27 To the authors’ knowledge, there are
no published studies evaluating the shock absorp-
tion capacity of zirconia. In the last few decades, the
growing patient demand for highly esthetic restora-
tions has led to the development of new all-ceramic
materials such as zirconia.
Zirconia minimizes the dark color transmit-
ted through peri-implant tissues associated with
metal components. Moreover, zirconia restorations
yield higher fracture loads than alumina or lithium
Both the increasing industrial pressure and grow-
ing enthusiasm for attractive esthetic outcomes have
led to the widespread use of all-ceramic restora-
tions and zirconia, even though their impact on the
masticatory system has not been sufficiently tested.
The esthetic characteristics, as well as the biocom-
patibility, and the most common shortcomings of all-
ceramic restorations (brittleness, chipping of the ve-
neering ceramic, fracture strength) have been thor-
oughly investigated for zirconia.40,58 Zirconia is also
considered to have excellent mechanical properties,59
but, so far, the biomechanical consequences of such
a rigid and stiff material in the masticatory system
have not been investigated by the scientific literature.
In fact, zirconia’s elastic modulus and coefficient of
abrasion are much higher than those of natural teeth.
Only a few studies60–62 report assessments of
periodontal or peri-implant tissues around teeth or
implants supporting zirconia restorations after func-
tional loading. To the authors’ knowledge, no clinical
studies report possible consequences at the level of
the antagonist arch or any gnathological consider-
ation. Moreover, to date, the observational period for
the majority of trials on zirconia restorations is quite
Two systematic reviews on all-ceramic dental
materials and zirconia also underlined the fact that
none of the cited clinical trials took bruxism into ac-
count. More often, such a parafunction figured into
the exclusion criteria. Consequently, the authors
suggested that, since parafunctions were not con-
sidered in any clinical investigation, they should be
regarded as a potential limitation for zirconia-based
554 The International Journal of Prosthodontics
Shock Absorption of Restorative Materials
restorations.39,6 3 One reason for this suggestion could
be the increased risk of chipping and fracture of
zirconia-based restorations in parafunctional pa-
tients, but evidence is lacking on possible harmful
effects on the masticatory system using zirconia res-
torations when a parafunction is present.
Larsson et al64 noticed that significantly more
porcelain veneer fractures are reported for implant-
supported zirconia fixed dental prostheses when
compared with tooth-supported restorations. One
explanation for this finding could be the role played
by the periodontal ligament, which allows for shock
absorption, sensory function, and tooth movement.
This hypothesis also suggests that the possible harm-
ful effects of zirconia restorations on the masticatory
system would be made worse when dealing with im-
plant-supported restorations in comparison to tooth-
supported restorations. In fact, a shock-absorbing
element is lacking in implant restorations and higher
loads can occur with implant-associated propriocep-
tion loss.52
The choice of the restorative material to be used
in implant restorations should be made in light of
newly introduced concepts of osseosufficiency and
osseoseparation5: as long as the host, the implant,
and the clinical procedures induce and allow for
maintaining osseointegration, an osseosufficiency
state is present. But some patient-related or nonpa-
tient-related factors could induce osseoseparation,
compromising the obtainment or maintenance of
osseointegration. As reported earlier, evidence is
lacking on the role of overloading in peri-implant
bone loss. However, bone has been demonstrated
to be sensitive to loading conditions.65 This suggests
that to control the occlusal loads in implant prosth-
odontics as much as possible, clinicians should aim
to reduce load entity and extra-axial loads. Based on
the present in vitro results, if the aim is reducing load
entity, zirconia is not the proper restorative material
to be used. These findings need to be supported by
clinical trials to investigate their clinical relevance
Within the limitations of this in vitro study, several
conclusions can be drawn. Zirconia, glass-ceramic,
and gold alloy transmitted higher stresses to the
simulated peri-implant bone. In contrast, composite
resin materials were able to significantly reduce the
values of force recorded compared to stiffer materi-
als. In fact, the use of composite resins and acrylic
resins reduced occlusal stress by up to –70.80% and
–95.59%, respectively, compared with zirconia.
The construction of the masticatory robot was financed by the
Ministr y of Instruction, Universit y and Research (MIUR), Italy,
under the auspices of the Research of National Interest Project s
(PRIN, 2002). The authors wish to thank Prof Giambattista Ravera
(Depar tment of Health Sciences, University of Genoa) for the sta-
tistical analysis, dental technician Paolo Pagliari for the labora-
tory support, and engineers Giuseppe Casalino, PhD, Fabio Giorgi,
Tommaso Bozzo, and Enrico Simetti (Depar tment of Informatics
of Systems Theory and Telematics, University of Genoa, Italy). The
authors repor ted no conflicts of interest related to this study.
1. Adell R, Eriksson B, Lekholm U, Brånemark PI, Jemt T. Long-
term follow-up study of osseointegrated implants in the treat-
ment of totally edentulous jaws. Int J Oral Maxillofac Implants
1990 ;5: 347–35 9.
2. Ekelund JA, Lindquist LW, Carlsson GE, Jemt T. Implant treat-
ment in the edentulous mandible: A prospective study on
Brånemark system implants over more than 20 years. Int J
Prosthodont 2003;16:602–608.
3. Jemt T, Johansson J. Implant treatment in the edentulous max-
illae: A 15-year follow-up study on 76 consecutive patients
provided with fixed prostheses. Clin Implant Dent Relat Res
2006; 8:61–69.
4. Snauwaert K, Duyck J, van Steenberghe D, Quir ynen M, Naer t
I. Time dependent failure rate and marginal bone loss of im-
plant suppor ted prostheses: A 15-year follow-up study. Clin
Oral Investig 2000;4:13–20.
5. Koka S, Zarb G. On osseointegration: The healing adaptation
principle in the context of osseosufficiency, osseoseparation,
and dental implant failure. Int J Prosthodont 2012;25:48–52.
6. Quir ynen M, Naert I, van Steenberghe D. Fixture design and
overload influence marginal bone loss and fix ture success in
the Brånemark system. Clin Oral Implants Res 1992;3:104–111.
7. Hoshaw SJ, Brunski JB, Cochran GVB. Mechanical loading of
Brånemark implants affect s inter facial bone modelling and re-
modelling. Int J Oral Maxillofac Implants 1994;9:345–360.
8. Isidor F. Loss of osseointegration caused by occlusal load of
oral implant s. A clinical and radiographic study in monkeys.
Clin Oral Implants Res 1996;7:143–152.
9. Isidor F. Histological evaluation of peri-implant bone at im-
plants subjected to occlusal overload or plaque accumulation.
Clin Oral Implants Res 1997;8:1–9.
10. Duyck J, R ønold HJ, Van Oosterw yck H, Naert I, Vander Sloten
J, Ellingsen JE. The influence of st atic and dynamic loading
on marginal bone reactions around osseointegrated implants:
An animal experimental study. Clin Oral Implants Res 2001;
12:207–218 .
11. Isidor F. Influence of forces on peri-implant bone. Clin Oral
Implants Res 2006;17(suppl 2):8–18.
12. Miyata T, Kobayashi Y, Araki H, Ohto T, Shin K. The influence
of controlled occlusal overload on peri-implant tissue. Part 3:
A histologic study in monkeys. Int J Oral Ma xillofac Implants
13. Brånemark PI, Hansson BO, Adell R, et al. Osseointegr ated im-
plants in the treatment of the edentulous jaw. Experience from
a 10-year period. Scand J Plast Reconstr Surg 1977;16:1–132.
14. Skalak R. Biomechanical considerations in osseointegrated
prostheses. J Prosthet Dent 1983;49:843–848.
Volume 26, Number 6, 2013 555
Menini et al
15. Frost HM. Wolf f’s law and bone’s structural adaptations to
mechanical usage: An overview for clinicians. Angle Orthod
16. Frost HM. Perspectives: Bone’s mechanical usage windows.
Bone Miner 1992;19: 257–271.
17. Uribe R, Peñarrocha M, Sanchis JM, García O. Marginal peri-
implantitis due to occlusal overload. A case report. Med Oral
18. Leung KC, Chow T W, Wat PY, Comfor t MB. Peri-implant bone
loss: Management of a patient. Int J Oral Maxillofac Implants
19. Tawil G. Peri-implant bone loss caused by occlusal overload:
Repair of the peri-implant defect following correction of
the traumatic occlusion. A case report. Int J Oral Ma xillofac
Implants 2008;23:153–157.
20. Miyata T, Kobayashi Y, Araki H, Motomura Y, Shin K. The influ-
ence of controlled occlusal overload on peri-implant tissue:
A histologic study in monkeys. Int J Oral Ma xillofac Implants
21. Çehreli MC, Iplikçioglu H. In vitro strain gauge analysis of axial
and off-axial loading on implant supported fixed partial den-
tures. Implant Dent 2002;11:286–292.
22. Hsu ML, Chen FC, K ao HC, Cheng CK. Influence of off-axis
loading of an anterior maxillary implant: A 3-dimensional fi-
nite element analysis. Int J Oral Maxillofac Implants 2007;
23. Goellner M, Schmitt J, K arl M, Wichmann M, Holst S. The effect
of axial and oblique loading on the micromovement of dental
implants. Int J Oral Maxillofac Implants 2011;26:257–264.
24. Sütpideler M, Eckert SE, Zobit z M, An K N. Finite element anal-
ysis of effect of prosthesis height, ancle of force application,
and implant offset on supporting bone. Int J Orl Maxillofac
Implants 2004;19:819–825.
25. O’Mahony A, Bowles Q, Woolsey G, Robinson SJ, Spencer P.
Stress distribution in the single-unit osseointegrated dental
implant: Finite element analyses of axial and off-axial loading.
Implant Dent 2000;9:207–218.
26. Conserva E, Menini M, Tealdo T, et al. Robotic chewing simula-
tor for dental materials testing on a sensor-equipped implant
set up. Int J Prosthodont 2008;21:501–508.
27. Conserva E, Menini M, Tealdo T, et al. The use of a mastica-
tory robot to analyze the shock absorption capacity of differ-
ent restorative materials for prosthetic implants: A preliminary
repor t. Int J Prosthodont 2009;22:53–55.
28. Rues S, Huber G, Rammelsberg P, Stober T. Effect of impact
velocit y and specimen stiffness on contact forces in a weight-
controlled chewing simulator. Dent Mater 2011;27:1267–1272.
29. Juodzbalys G, Kubilius R, Eidukynas V, Raustia AM. Stress
distribution in bone: Single-unit implant prostheses veneered
with por celain or a new compos ite material. Implan t Dent 2005;
14:166 –175.
30. Çiftçi Y, Canay S. The effect of veneering materials on stress
distribution in implant-supported fixed prosthetic restorations.
Int J Oral Maxillofac Implants 2000;15:571−585.
31. Inan O, Kesim B. Evaluation of the ef fects of restorative materi-
als used for occlusal surfaces of implant-supported prosthe-
ses on force distribution. Implant Dent 1999;8:311–316.
32. Gracis SE, Nicholls JI, Chalupnik JD, Youdelis RA. Shock-
absorbing behaviour of five restorative materials used on im-
plants. Int J Prosthodont 1991;4:282–291.
33. Brånemark PI. Osseointegration and its experimental back-
ground. J Prosthet Dent 1983;50:399–410.
34. Davis DM, Rimrott R, Zarb GA. Studies on frameworks for os-
seointegrated prostheses: Part 2. The effect of adding acrylic
resin or porcelain to form the occlusal superstructure. Int J
Oral Maxillofac Implants 1988;3:275–280.
35. Carlsson GE. Dental occlusion: Modern concepts and their ap-
plication in implant prosthodontics. Odontology 2009;97:8–17.
36. Taylor TD, Wiens J, C arr A. Evidence-based considerations for
removable prosthodontic and dental implant occlusion: A lit-
erature review. J Prosthet Dent 2005;6:555–560.
37. Wood MR, Vermilyea SG. A review of selected dental literature
on evidence-based treatment planning for dental implants:
Report of the Committee on Research in Fixed Prosthodontics
of the Academy of Fixed Prosthodontics. J Prosthet Dent 2004;
92:4 47− 462 .
38. ¸Sahin S, Çehereli MC, Yalçin E. The influence of functional
forces on the biomechanics of implant-supported prostheses:
A review. J Dent 2002;78:271–282.
39. Zarone F, Russo S, Sorrentino R. From porcelain-fused-to-
metal to zirconia: Clinical and experimental considerations.
Dent Mater 2011;27:83–96.
40. Hisbergues M, Vendeville S, Vendeville P. Zirconia: Established
facts and perspectives for a biomaterial in dental implantology.
J Biomed Mater Res B Appl Biomater 2009;88:519–529.
41. Duyck J, Van Oosterwyck H, Vander Sloten J, De Cooman M,
Puers R , Naer t I. Influence of prosthesis material on the load-
ing of implants that support a fixed partial prosthesis: In vivo
study. Clin Implant Dent Relat Res 2000;2:100–109.
42. Stegaroiu R, Khraisat A , Nomura S, Miyakawa O. Influence
of superstructure materials on strain around an implant un-
der 2 loading conditions: A technical investigation. Int J Oral
Maxillofac Implants 2004;19:735−742.
43. Bassit R , Lindström H, Rangert B. In vivo registration of force
development with ceramic and acrylic resin occlusal materi-
als on implant-supported prostheses. Int J Oral Maxillofac
Implants 2002;17:17−23.
44. Wang TM, Leu LJ, Wang JS, Lin LD. Effects of prosthesis ma-
terials and prosthesis splinting on peri-implant bone stress
around implants in poor-quality bone: A numeric analysis. Int J
Oral Maxillofac Implants 2002;17:231–237.
45. Soumeire J, Dejou J. Shock absorbabilit y of various restorative
materials used on implants. J Oral Rehabil 1999;26:394−401.
46. Sertgoz A. Finite element analysis study of the effect of su-
perstructure material on stress distribution in an implant-sup-
ported fixed prosthesis. Int J Prosthodont 1997;10:19−27.
47. Papavasiliou G, Kamposiora P, Bayne SC, Felton DA. Three-
dimensional finite element analysis of stress-distribution
around single tooth implants as a function of bony suppor t,
prosthesis type, and loading during function. J Prosthet Dent
48. Cibirka RM, Raz zoog ME, Lang BR, Stohler CS. Determining
the force absorption quotient for restorative materials used in
implant occlusal surfaces. J Prosthet Dent 1992;67:361–364.
49. Hobkirk JA, Psarros K J. The influence of occlusal surface
material on peak masticatory forces using osseointegrated
implant-supported prostheses. Int J Oral Maxillofac Implants
1992 ;7: 34 5–35 2.
50. Geng JP, Tan KBC, Liu GR. Application of finite element analy-
sis in implant dentistr y: A review of the literature. J Prosthet
Dent 2001;85:585–598.
51. Hürzeler MB, Quiñones CR, Schüpbach P, Vlassis JM, Strub
JR, Caffesse RG. Influence of the suprastructure on the
peri-implant tissues in beagle dogs. Clin Oral Implants Res
556 The International Journal of Prosthodontics
Shock Absorption of Restorative Materials
52. Trulsson, M. Sensor y and motor function of teeth and den-
tal implants: Basis for osseoperception. Clin Exp Pharmacol
Physiol 2005;32:119–122.
53. Jacobs R, Van Steenberghe D. From osseoperception to im-
plant-mediated sensory-motor interactions and related clini-
cal implications. J Oral Rehabil 2006;33:282–292.
54. Ogawa T, Dhaliwal S, Naert I, et al. Impact of implant number,
distribution and prosthesis material on loading on implants
supporting fixed prostheses. J Oral Rehabil 2010;37:525–531.
55. Stegaroiu R , Kusakari H, Nishiyama S, Miyakawa O. Influence
of prosthesis material on stress distribution in bone and im-
plant: A 3-dimensional finite element analysis. Int J Oral
Maxillofac Implants 1998;13:781–790.
56. Schley J-S, Heussen N, Reich S, Fischer J, Haselhuhn K,
Wolfart S. Survival probability of zirconia-based fixed dental
prostheses up to 5 yr: A systematic review of the literature. Eur
J Oral Sci 2010;118:443–450.
57. Raigrodski AJ, Hillstead MB, Meng GK, Chung KH. Sur vival
and complications of zirconia-based fixed dental prostheses:
A systematic review. J Prosthet Dent 2012;107:170–177.
58. Heintze SD, Rousson V. Sur vival of zirconia- and metal-sup-
ported fixed dental prostheses: A systematic review. Int J
Prosthodont 2010;23:493–502.
59. Pelaez J, Cogolludo PG, Serrano B, Lozano JFL, Suárez MJ. A
four-year prospective clinical evaluation of zirconia and metal-
ceramic posterior fixed dental prostheses. Int J Prosthodont
60. Linkevicius T, Apse P. Influence of abutment material on sta-
bility of peri-implant tissues: A systematic review. Int J Oral
Maxillofac Implants 2008;23:449–456.
61. Hosseini M, Worsaae N, Schiodt M, Gotfredsen K. A 1-year
randomised controlled trial comparing zirconia versus metal-
ceramic implant supported single-tooth restorations. Eur J
Oral Implantol 2011;4:347–361.
62. Hosseini M, Worsaae N, Schiødt M, Gotfredsen K. A 3-year
prospective study of implant-supported, single-tooth restora-
tions of all-ceramic and metal-ceramic materials in patients
with tooth agenesis [epub ahead of print]. Clin Oral Implants
Res 2012 Jun 18.
63. Al-Amleh B, Lyons K, Swain M. Clinical trials in zirconia: A sys-
tematic review. J Or al Rehabil 2010;37:641–652.
64. Larsson C, von Steyern PV, Nilner K . A prospective study of
implant-supported full-arch yttria-stabilized tetragonal zirco-
nia polycrystal mandibular fixed dental prostheses: Three-year
results. Int J Prosthodont 2010;23:364–369.
65. Marot ti G. The osteocyte as a wiring transmission system.
J Musculoskel Neuron Interact 2000;1:133–136.
Literature Abstract
Identification of risk factors for fracture of veneering materials and screw loosening of implant-supported fixed partial
dentures in partially edentulous cases
The purpose of this retrospective study was to determine the risk factors for fracture of veneering materials and screw loosening of
implant-supported fixed partial dentures. A total of 182 patients had 219 suprastructures inserted. One hundred twenty patients (149
facing suprastructures) were included in a subgroup to investigate the risk factors of fracture of veneering materials, and 81 patients
(92 suprastructures) were included in a subgroup to analyze the risk factors for abutment screw loosening. A Cox proportional haz-
ards regression model was performed to identify the risk factors related to technical complications, and eight factors were regarded
as candidate risk factors. It was suggested that a screw-retained suprastructure was a significant risk factor for fracture of veneering
materials, and connection of suprastructures with natural teeth was a significant risk factor for screw loosening. Further investigations
involving dynamic factors, such as occlusal force and bruxism, should be considered as predictors that may be helpful in studying the
risk factors of fracture of veneering materials and screw loosening.
Noda K, Arakawa H , Maekawa K, Hara ES, Yamaz aki S, Kimura- Ono A , Sonoyama W, Minakuchi H, Matsuka Y, Kuboki T. J Oral Rehabil
2013;40:214–220 . Reprints: Takuo Kuboki, Depar tment of Oral Rehabilitation and Re generative Medi cine, Okayama University, Graduate School
of Medicine, Dentistry and Pharmac eutical Scien ces, Okayama, 700 -8525, Japan. Email:—Arthur S. Sham,
Hong Kong
... High loads are linked to bone resorption and in some cases might lead to implant failure (1). Whereas low stimulation is known to cause bone resorption due to disuse atrophy through a phenomenon known as stress shielding (2,3). ...
... Consequently, the amount of load transferred through the implant-prosthesis complex to the bone is a critical success factor. Unlike natural teeth, implants lack the damping effect of the periodontal ligaments, therefore the amount of load transferred to the peri-implant bone is strongly affected by the prosthetic design (2)(3)(4)(5)(6). ...
... Regardless of the prosthesis design, the material of choice affects the quantity and quality of stress and strain developing at the implant-bone interface (3,4). Due to the low modulus of elasticity, polyetheretherketone (PEEK) could provide a damping effect required to prevent overloading of the peri-implant bone (2,4,8). This damping or shock-absorbing effect could reduce the loads transmitted to the bone or implant-bone interface, which consequently reduces the micromovement between the abutment and implant and mitigates possible technical complications such as fracture of the screw or the ceramic components (5,9). ...
Aim: To investigate the effect of using different materials for the fabrication of implant abutments and crowns on the mechanical behavior of implant-supported single crowns after artificial aging. The materials were tested in different combinations to reveal whether using stiff or resilient materials as an abutment or a crown material might influence the fracture strength of the whole structure. Materials and methods: A total of 40 implants (blueSKY, bredent GmbH & Co. KG) were restored with identical custom-made CAD/CAM abutments milled out of lithium disilicate or ceramic-reinforced PEEK and were divided into 5 test groups (n = 8 each). Forty crowns made of three different materials (zirconia, lithium disilicate, and ceramic-reinforced PEEK) were used to restore the abutments. Specimens were subjected to mechanical load up to 1,200,000 cycles in a chewing simulator (Kausimulator, Willytech) with additional thermal cycling. The surviving specimens were subjected to quasi-static loading using a universal testing machine (Z010, Zwick). Results: PEEK abutments with zirconia crowns showed the highest median failure load (3890.5 N), while PEEK abutments with lithium disilicate crowns exhibited the lowest (1920 N). Fracture and deformation occurred in both crowns and abutments. Conclusion: The failure load of the restorations was influenced by the material of the abutment and the crown. Restoring PEEK abutments with zirconia crowns showed a high failure load and no screw loosening.
... On the other hand, zirconia crowns have a high modulus of elasticity, so they transmit more forces to the bone implant interface and increase crestal bone loss. 41,42 On the contrary to the radiographic results, Kortam et al 16 concluded that the PEEK framework reduces the peri-implant bone loss as the material has a dampening effect that reduces the occlusal forces of opposing occlusion. The difference in our results might be due to the presence of zirconia combined with PEEK, which may reduce its shock absorbing effect, increase the stresses on bone, and thus increase bone resorption. ...
... Ferner wird davon ausgegangen, dass okklusale -insbesondere extraaxiale -Belastung ein wichtiger Faktor für die Implantateinheilung und den Langzeiterfolg sein kann. Studienergebnisse lassen zudem darauf schließen, dass die Dämpfungskapazität von Implantatrestaurationen u. a. abhängig von der Steifigkeit der Restaurationsmaterialien ist 26 ...
Enossale Implantate gelten heute als ein Mittel der Wahl, um Zähne zu ersetzen und Funktion, Ästhetik sowie Lebensqualität des Patienten wiederherzustellen. Hierbei können diese als Halteelemente für herausnehmbaren oder als Pfeiler für festsitzenden Zahnersatz dienen. Dieser Artikel beleuchtet die physikalischen Eigenschaften implantatgetragener Einzelzahnrestaurationen. Hierbei zeigen die Kombinationsmöglichkeiten unterschiedlicher Restaurationsmaterialien eine vielversprechende Entwicklung. So wirken sich Restaurationsmaterialien mit geringem Elastizitätsmodul günstig auf periimplantäre Strukturen aus. Oberstes Ziel heutiger dentaler Implantologie ist der langfristige Implantaterhalt durch patienten- und indikationsgerechte Therapie. Dieser Artikel stellt die Dämpfungskapazität und ihren Einfluss auf implantatgetragene Einzelzahnrestaurationen dar.
... The restorative material choice, already crucial on natural teeth, becomes even more important in a system with reduced abutment mobility, such as the implant-supported crown. In these terms, LDS restorations, with their lower modulus of elasticity, could be a valid alternative to zirconia [35]. This is so true that LDS crowns are being increasingly used for single-unit implant-supported restorations [36][37][38][39][40][41]. ...
Full-text available
Lithium disilicate (LDS) glass ceramics are among the most common biomaterials in conservative dentistry and prosthodontics, and their wear behavior is of paramount clinical interest. An innovative in vitro model is presented, which employs CAD/CAM technology to simulate the periodontal ligament and alveolar bone. The model aims to evaluate the effect of the abutment rigidity on the wear resistance of the LDS glass ceramic. Two experimental groups (LDS restorations supported by dental implants, named LDS-on-Implant, or by hybrid ceramic tooth replicas with artificial periodontal ligament, named LDS-on-Tooth-Replica) and a control group (LDS-Cylinders) were compared. Fifteen samples (n = 15) were fabricated for each group and subjected to testing, with LDS antagonistic cusps opposing them over 120,000 cycles using a dual axis chewing simulator. Wear resistance was analyzed by measuring the vertical wear depth (mm) and the volume loss (mm3) on each LDS sample, as well as the linear antagonist wear (mm) on LDS cusps. Mean values were calculated for LDS-Cylinders (0.186 mm, 0.322 mm3, 0.220 mm, respectively), LDS-on-Implant (0.128 mm, 0.166 mm3, 0.199 mm, respectively), and LDS-on-Tooth-Replica (0.098 mm, 0.107 mm3, 0.172 mm, respectively) and compared using one-way-ANOVA and Tukey’s tests. The level of significance was set at 0.05 in all tests. Wear facets were inspected under a scanning electron microscope. Data analysis revealed that abutment rigidity was able to significantly affect the wear pattern of LDS, which seems to be more intense on rigid implant-abutment supports compared to resilient teeth replicas with artificial periodontal ligament.
... Lithium and zirconia have high strength and a low elasticity modulus, which makes them friable without deformation capacity. Materials with a lower modulus of elasticity, such as, for example, resin-based materials PMMA (polymethylmethacrylate), PEEK (polyether ether ketone) and hybrid resins, can be a viable alternative, as they deform and thus reduce the transmission of forces [40][41][42][43]. ...
Full-text available
Background: The objective of this study was to evaluate the load transmitted to the peri-implant bone by seven different restorative materials in single-unit rehabilitations with morse taper implants using a strain gauge. Materials: In a polyurethane block that simulated type III bone, a morse taper platform implant was installed (3.5 × 11 mm) in the center and 1 mm below the test base surface, and four strain gauges were installed around the implant, simulating the mesial, distal, buccal and lingual positions. Seven similar hybrid abutment crowns were crafted to simulate a lower premolar using different materials: 1—PMMA; 2—glass ceramic over resin matrix; 3—PEEK + lithium disilicate; 4—metal–ceramic; 5—lithium disilicate; 6—zirconia + feldspathic; 7—monolithic zirconia. All groups underwent axial and oblique loads (45 degrees) of 150 N from a universal testing machine. Five measurements (n = 5) were performed with each material and for each load type; the microdeformation data underwent statistical analysis. The data were obtained in microdeformation (με), and the significance level was set at p ≤ 0.05. Results: There was no statistically significant difference in the evaluation among the materials under either the axial load or the oblique load at 45 degrees. In turn, in the comparison between axial load and oblique load, there was a difference in load for all materials. Conclusion: The restorative material did not influence the load transmitted to the bone. Furthermore, the load transmitted to the bone was greater when it occurred obliquely at 45° regardless of the material used. In conclusion, it appeared that the different elastic modulus of each material did not influence the load transmission to the peri-implant bone.
... There is no periodontal ligament in dental implants; if a high-strength material such as zirconia is used for crown restoration at both the upper and lower sides, it will bring greater concentrated stress and long-term fatigue impact to the implant, which may affect the stability of the implant [1]. According to the reports of Sahin et al. [2] and Menini et al. [3], crown restoration with resin material can compensate for the high elastic modulus of the implant material, and thus it can reduce the impact of the implant on the surrounding bone. Natural teeth undergo physiological wear, while ceramic materials such as zirconia have high hardness and less wear; thus, long-term use and uneven wear between natural teeth may cause occlusal interference [4]. ...
Full-text available
Abstract Background The purpose of this study is to investigate the performance and fracture resistance of different resin-matrix ceramic materials for use in implant-supported single crowns with respect to the abutment design (crown thickness: 1 mm, 2 and 3 mm). Methods Forty-eight abutments and crowns were fabricated on implants in the right lower first molar. Two resin-matrix ceramic materials for dental crowns were selected for study: (1) a glass-ceramic in a resin interpenetrating matrix (Vita Enamic, Vita, Germany) and (2) a resin-based composite with nanoparticle ceramic filler (Lava Ultimate, 3 M ESPE, USA). Three types of abutments were designed: 1 mm thick crown + custom titanium abutment, 2 mm thick crown + custom titanium abutment and 3 mm thick crown + prefabricated titanium abutment. The experiment was divided into 6 groups (n = 8) according to the crown materials and abutment designs. After 10,000 thermocycles, fracture resistance was measured using a universal testing machine. The statistical significance of differences between various groups were analysed with ANOVA followed by a post hoc Tukey’s honestly significant difference test. The surfaces of the fractured specimens were examined with scanning electron microscopy (SEM). Results Two-way ANOVA revealed that the abutment design (F = 28.44, P = 1.52 × 10− 8
Background Lithium disilicate can be reliable when restoring implants in the esthetic zone. However, it has a high elastic modulus. This might increase the amount of forces transmitted to the crestal bone. Aim of the Study To evaluate the crestal bone loss and peri‐implant periodontal parameters of polymer infiltrated ceramic network compared to lithium disilicate implant‐supported hybrid abutment crowns after 12 months of follow‐up. Methodology 44 patients were enrolled. They were randomly assigned into two groups ( n = 22). The first group received 22 implants restored with polymer‐infiltrated ceramic network (Vitaenamic) hybrid abutment crowns. The second group received 22 implants restored with lithium disilicate (e.max) hybrid abutment crowns over immediately placed implants in the esthetic zone. Periapical radiographs were taken immediately after prosthetic placement and 1 year later utilizing a parallel technique, to assess crestal bone loss. Periodontal parameters were assessed after 1 year. Results Regarding crestal bone loss, a comparison between group I (Vitaenamic) and group II (e.max) was made by using an Independent t‐test, which showed an insignificant difference between them ( p > 0.05). A comparison between groups I and II revealed insignificant differences regarding periodontal parameters (probing depth, bleeding on probing, visible plaque, and suppuration). Conclusions Regarding bone stability and periodontal parameters, polymer infiltrated ceramic network and lithium disilicate hybrid abutment crowns showed comparable results. Both materials showed clinically acceptable hard and soft tissue responses.
Aim This study aimed to investigate the influence of titanium base (ti‐base) abutment macro and micro geometry on the mechanical stability of polymer‐infiltrated ceramic network (PICN) screw‐retained implant‐supported single crowns (iSCs). Materials and Methods Twelve specimens per group were used, comprising six different implant/ti‐base abutment combinations restored with PICN iSCs: Nb‐T (gingival height [GH]: 1.5 mm, prosthetic height [PH]: 4.3 mm), CC (GH: 0.8 mm, PH: 4.3 mm), CC‐P (GH: 0.8 mm, PH: 7 mm), Nb‐V (GH: 1.5 mm, PH: 6 mm), St (GH: 1.5 mm, PH: 5.5 mm), and Th (GH: 0.5 mm, PH: 9 mm). The specimens underwent thermo‐mechanical aging, and those that survived were subsequently subjected to static loading until failure. The data was analysed using a one‐way ANOVA test followed by Tukey post hoc test. (α = .05) Results All specimens survived thermo‐mechanical aging without complications namely visible cracks, debonding, or screw loosening. Th group demonstrated the highest strength values among all the groups, with significant differences compared to Nb‐T (p < .05), CC (p < .001), and St (p < .001). Additionally, CC‐P group exhibited significantly superior fracture strength results compared to CC (p < .05) and St (p < .05). Conclusion The choice of ti‐base, particularly prosthetic height had a significant influence on fracture resistance of PICN iSCs. Nevertheless, the height or geometrical features of the ti‐base did not exhibit a significant influence on the mechanical behaviour of the iSC/ti‐base assembly under thermomechanical loading, as all specimens withstood the aging without complication or failure.
Objective: In this study, a preclinical approach was used to analyze and directly compare the fatigue performance (fatigue life and damage percentage) and maximum principal stresses (Max. Ps) of prepared models treated with different materials and geometric parameters. Methods: Four groups of preparative parameters (crown width, crown length, degree of polymerization and material) were selected, each with five variables. An alternating cyclic occlusal load with an amplitude of 300 N was applied to the ball part along the longitudinal axis. The fatigue properties of the preparations and Max.Ps were analyzed. Results: A shoulder width of 0.8 mm, a shoulder height offset of 0.2 mm, a degree of polymerization of 5°, and a crown material of ZC resulted in the smallest percentage of damage. In contrast, the effect of different modulus of elasticity (MOE) on Max.Ps was not significant (p = 0.609). Conclusion: The results suggest that the selection of larger modulus of elasticity MOE and larger Poisson's ratio material's, preparation of larger shoulder widths within safety, reasonable increase in crown length, and selection of larger degree of polymerization are favorable methods to protect the preparation.
Purpose: This in vitro study was to assess the effects of using different cements and titanium copings design on the retention of the implant-supported fixed dental prostheses (IFDPs) using a pull-out test. Materials and methods: Fifty zirconia (ZirCAD; Ivoclar Vivadent) and 20 prepolymerized denture acrylic resin (AvaDent) rectangular (36 mm × 12 mm × 8 mm) specimens were milled to mimic the lower left segmental portion of the All-on-Four IFDPs. Cylindrical titanium copings (Variobase; Straumann) (V) were used in 2 prepolymerized denture acrylic resin groups (n = 10) while conical titanium copings (Straumann) (C) were used as a control group for zirconia with 4 groups using cylindrical titanium copings. Before cementation, the outer surfaces of all titanium copings and intaglio bonding surface of prosthetic specimens were airborne-particle abraded. All specimens were cemented following the manufacturer recommendations and instructions according to the experimental design. After artificial aging (5000 cycles of 5°C-55°C, dwelling time 20 sec; 150 N, 1.5 Hz in a 37°C water bath), all specimens were subjected to retention force testing using a pull-out test using a universal testing machine and a custom fixture with a crosshead speed 5 mm/min. Mode of failure were classified (Type 1, 2, or 3). Retention force values were analyzed by the t-test for the prepolymerized denture acrylic resin specimen groups, and 1-way ANOVA and the Tukey test for the zirconia groups at α = 0.05. Results: Mean and standard deviation retention force values varied from 101.1±67.1 to 509.0 ±65.2 N for the prepolymerized denture acrylic resin specimen groups. The zirconia groups ranged from 572.8 ±274.7 to 1416.1 ±258.0 N. There is no statistically significant difference in retention force values between V and C specimens cementing to Zirconia with Panavia SA cement (Kuraray Noritake) (p = 0.587). The retention forces and failure modes were influenced by the cement used (p < 0.05). Modes of failure were predominantly Type 2 (Mixed failure) and Type 1 (Adhesive fracture from prosthetic materials) except for the quick-set resin group (Type 3, Adhesive failure from coping). Conclusions: When bonding IFDPs onto titanium copings, quick-set resin provided significantly higher retention force for prepolymerized denture acrylic resin prostheses. Conical and cylindrical titanium copings performed similarly when cemented to Zirconia with Panavia SA cement under the same protocol. The stability of the bonded interface and retention forces between zirconia prostheses and titanium copings varied from the cement used. This article is protected by copyright. All rights reserved.
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To compare the biological, technical and aesthetic outcomes of single implant-supported all-ceramic versus metal-ceramic crowns. Thirty-six patients with premolar agenesis were randomly treated with 38 all-ceramic (AC) and 37 metal-ceramic (MC) implant-supported single-tooth restorations. A quasi-randomisation of consecutively included restorations in patients with one or more implants was used, i.e. a combination of parallel group (for 13 patients with one restoration) and split-mouth (for 23 patients with ≥2 restorations). All patients were recalled for baseline and 1-year followup examinations. Biological and technical outcomes, including complications, were clinically and radiographically registered. The Copenhagen Index Score and visual analogue scale (VAS) score were used to assess professional and patient-reported aesthetic outcomes, respectively, by blinded assessors. One-year after loading, no patient dropped out and no implant failed, though one MC restoration had to be remade. The marginal bone loss was not significantly different between AC and MC restorations (AC: mean 0.08 mm, SD 0.25; MC: mean 0.10 mm, SD 0.17). Seven out of 10 inflammatory reactions were registered at AC restorations. Two technical complications, one loss of retention and one chipping of veneering porcelain were recorded at two metal-ceramic crowns. The marginal adaptation of the all-ceramic crowns was significantly less optimal than the metal-ceramic crowns (P = 0.014). The professional-reported colour match of all-ceramic crowns was significantly better than metal-ceramic crowns (P = 0.031), but other aesthetic parameters as well as the VAS scores demonstrated no statistically significant difference between AC and MC restorations. Marginal bone loss and the aesthetic outcomes were not significantly different between AC and MC restorations in this short-term follow-up study, though inflammatory reactions in the peri-implant mucosa as well as less optimal marginal adaptation were more frequently registered for all-ceramic compared to the metal-ceramic crowns.
This literature review summarizes research with the aim of providing dentists with evidence-based guidelines to apply when planning treatment with osseointegrated implants. Peer-reviewed literature published in the English language between 1969 and 2003 was reviewed using Medline and hand searches. Topics reviewed include systemic host factors such as age, gender, various medical conditions, and patient habits, local host factors involving the quantity and quality of bone and soft tissue, presence of present or past infection and occlusion, prosthetic design factors, including the number and arrangement of implants, size and coatings of implants, cantilevers and connections to natural teeth, and methods to improve outcomes of implant treatment in each category. The review demonstrated that there is no systemic factor or habit that is an absolute contraindication to the placement of osseointegrated implants in the adult patient, although cessation of smoking can improve outcome significantly. The most important local patient factor for successful treatment is the quality and quantity of bone available at the implant site. Specific design criteria are provided, including guidelines for spacing of implants, size, materials, occlusion, and fit. Limitations in the current body of knowledge are identified, and directions for future research are suggested.
A study was conducted to investigate the hypothesis that mechanical loading of implants and the consequent stress and strain fields influence bone modeling and remodeling at the bone-implant interface. Two implants ad modum Brånemark were placed in each of 20 canine tibiae, allowed to heal for I year, and then subjected to a controlled loading protocol. Implants in the left limb were loaded in axial tension with a triangular waveform (300 N maximum, 10 N minimum, 330 N/s) for 500 cycles per day for 5 consecutive days; implants in the right limb served as unloaded controls. Twelve weeks after loading, polished undecalcified thick sections were examined with light and scanning electron microscopy to provide bone modeling and remodeling data, including the surface area of periosteal and endocortical modeling, the percentage of mineralized tissue in the bone threads, and the frequency of occurrence of preloading and postloading fluorochrome bone labels. Also, a three-dimensional finite element model was developed to investigate the strain state in the bone near loaded implants. The morphometric data were statistically analyzed in terms of individual load-control pairs and showed the following trends for loaded implants: (1) a net bone loss near the coronal portion of the implant, (2) a smaller percentage of mineralized tissue in the cortex, and (3) a decreased frequency of occurrence of postloading fluorochrome bone label in the cortex adjacent to the implant. The finite element model indicated regions of high strain on the periosteal surface adjacent to the loaded implants. The results support the premise that the bone loss observed around the neck of the loaded implants at 12 weeks postloading was a consequence of bone modeling and remodeling secondary to bone microdamage caused by the loading protocol. This scenario, as well as certain other features of the bone response at the interfaces, can be interpreted in light of existing bone modeling and remodeling theories that relate bone activities and mechanical loading. When considering any load-bearing implant in bone, it is important to understand not only the mechanics of stress transfer at the interface, but also the biological response of the interfacial tissues to these stresses. The ability to maintain a healthy bone-implant interface is widely believed to be critical to the survival of the implant. JOMI on CD-ROM, 1994 Mar (345-360): Mechanical Loading of Brånemark Implants Af… Copyrights © 1997 Quinte… 1 Although success rates for most dental implant designs are good, implant failure is often characterized by minor to massive bone loss, implant mobility, and the inability of the implant to perform its intended function.2 The importance of mechanical factors in dental implant failure cannot be overlooked given the increased incidence of component fracture,3,4 coronal bone resorption,5 and fixture loss6 in situations of compromised prosthetic reconstruction and long-term loading. The exact nature of the mechanical stimuli resulting in bone destruction or deposition and the biological response to such stimuli has yet to be established. The objective of this study was to investigate interfacial bone response to implant loading in a controlled model system and to examine the response of the interfacial tissues in terms of general bone modeling and remodeling concepts. The bone biology literature has used the terms bone modeling and bone remodeling nearly interchangeably to describe almost all types of bone growth and turnover. Recent publications7,8 have distinguished between the two terms and have given separate definitions, which will be adopted here. Bone modeling has been defined as the deposition or removal of bone from bone surfaces. Modeling produces an overall change in the size or shape of the bone via activation followed by either formation or resorption. Bone remodeling, however, involves activation followed by a sequence of bone resorption and formation that results in the formation of a secondary osteon within the existing bone tissue. A remodeling cycle rarely alters gross bone architecture or size.
Although the favorable mechanical properties of zirconium oxide-based ceramics have increased the acceptance of fixed dental prostheses for use in the posterior regions of the mouth in recent years, there are few clinical studies documenting the longevity of these restorations. Furthermore, certain complications must be resolved before the material is used more extensively. The purpose of this randomized prospective study was to evaluate the clinical performance of zirconia (Lava) 3-unit posterior fixed dental prostheses. Twenty 3-unit fixed dental prostheses were placed in 17 participants to replace a second premolar or a first molar. Eleven were placed in the maxilla and 9 in the mandible. All abutment teeth were prepared with a chamfer finish line of 0.8 to 1 mm, and frameworks were prepared with the Lava system. Restorations were cemented with a resin cement. Two calibrated examiners independently evaluated the fixed dental prostheses 1 week (baseline) and 1, 2, and 3 years after placement with the California Dental Association quality evaluation system. The periodontal parameters: the gingival index, plaque index, margin index, and the probing depths of abutment teeth and contralateral teeth were assessed. Data were analyzed by using descriptive statistics and the Wilcoxon signed-rank test (α=.05). All fixed dental prostheses were rated satisfactory after 3 years, and no fracture of the framework was observed during the observation period. One fixed dental prostheses was lost because of a biological complication at the 3-year examination, and a small degree of chipping of the veneering ceramic was observed in 2 participants. No significant differences among the periodontal parameters of the test and control teeth were observed except for the margin index. The results of a 3-year evaluation suggest that posterior zirconia 3-unit fixed dental prostheses are a reliable treatment.
The aim of this study was to compare the survival rates and biologic and technical complications of three-unit metal-ceramic posterior fixed dental prostheses (FDPs) with those obtained with zirconia frameworks. Thirty-seven patients in need of 40 three-unit posterior FDPs were included in this study. The FDPs were randomly assigned to 20 zirconia and 20 metal-ceramic restorations. Abutment preparation guidelines consisted of a 1-mm-wide circumferential chamfer, axial reduction of 1 mm, and occlusal reduction of 1.5 to 2 mm. At baseline and 1, 2, 3, and 4 years after cementation, success of both types of restorations was evaluated. The restorations were assessed using the California Dental Association's assessment system. Periodontal parameters were assessed by determining the Plaque Index (PI), Gingival Index (GI), Marginal Index (MI), and pocket depth of the abutment and control teeth. Statistical analysis was performed by applying Wilcoxon rank sum and Wilcoxon signed-rank tests. Patients were examined after a mean observation period of 50 ± 2.4 months. The survival rates for metal-ceramic and zirconia restorations were 100% and 95%, respectively. One biologic complication in a zirconia FDP was observed at the 3-year follow-up. No fractures of the zirconia or metal frameworks were observed. Restorations from both groups were assessed as satisfactory. Minor chipping of the veneering ceramic was observed in 2 zirconia FDPs after 4 years. No significant differences were observed between abutment and contralateral teeth for either type of restoration or within the groups with regard to PI, GI, and pocket depth. Zirconia-based FDPs demonstrated a similar survival rate to metal-ceramic FDPs after medium-term clinical use.
The purpose of this study was to compare clinical, radiographic and histological differences around titanium oral implants loaded with either acrylic-veneered metal or ceramo-metal fixed prostheses. Five beagle dogs were used in this investigation. At the beginning of the study, all mandibular premolars and first molars were extracted. After 3 months of healing, 2 Brånemark implants were installed on each side of the mandibles. Three months later, abutments were inserted on each implant and a daily oral hygiene regime was initiated. One month after abutment connection, the implants on one side of the mandible were restored with an acrylic-veneered metal fixed prosthesis, whereas, on the other side a ceramo-metal fixed prosthesis was inserted. The prostheses were constructed in occlusion with the maxillary first molars. The following clinical parameters were measured around each implant at this time (i.e., baseline), and thereafter, at monthly intervals up to 5 months: Plaque Index; Gingival Index; implant mobility (using the Periotest®); probing depth and clinical attachment level (using the Florida Probe®). In addition, standardized radiographs were taken at baseline and 5 months after insertion of the prostheses and evaluated by subtraction radiography. Another Brånemark fixture was installed on each side of the mandibles 3 months before the end of the study. These implants remained unloaded and submerged for the entire study period. Five months after prosthesis insertion, the animals were killed, and implants with their supporting peri-implant tissues were processed for histological evaluation. Analyses of the clinical, radiographic and histometric parameters revealed no significant differences between the acrylic-veneered and ceramometal loaded implants. All clinical and radiographic parameters remained stable over time. Histological comparison of the alveolar bone height levels around both loaded groups with those from the unloaded, submerged implants revealed that a similar and slight loss of bone height (approximately 0.6 mm) occurred on the loaded groups following abutment connection. It was concluded that both acrylic-veneered metal and ceramo-metal suprastructures appear to be suitable for the restoration of endosseous oral implants. Additional long-term studies in humans, however, are needed evaluating both types of implant-supported prostheses, in a variety of clinical conditions. before final restorative recommendations are made.
Objectives: The purpose of this clinical study was to describe outcome variables of all-ceramic and metal-ceramic implant-supported, single-tooth restorations. Materials and methods: A total of 59 patients (mean age: 27.9 years) with tooth agenesis and treated with 98 implant-supported single-tooth restorations were included in this study. Two patients did not attend baseline examination, but all patients were followed for 3 years. The implants supported 52 zirconia, 21 titanium and 25 gold alloy abutments, which retained 64 all-ceramic and 34 metal-ceramic crowns. At baseline and 3-year follow-up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data and PROC NLMIXED for ordinal categorical data. Results: The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P = 0.040). The mPlI and mBI were not significantly different at three abutment materials. The frequency of biological complications was higher at restorations with all-ceramic restorations than metal-ceramic crowns. Loss of retention, which was only observed at metal-ceramic crowns, was the most frequent technical complication, and the marginal adaptations of all-ceramic crowns were significantly less optimal than metal-ceramic crowns (P = 0.020). The professional-reported aesthetic outcome demonstrated significantly superior colour match of all-ceramic over metal-ceramic crowns (P = 0.015). However, no significant differences in the other aesthetic parameters at various restoration materials were registered. After 3 years, the patient-reported outcome variables at different restoration materials were not significantly different. Conclusion: The biological outcomes at the zirconia and metal abutments were comparable. All-ceramic crowns demonstrated better colour match, but higher frequency of marginal discrepancy compared to metal-ceramic crowns. Generally, the patients noticed no difference in aesthetic outcome of all-ceramic and metal-ceramic restorations.
Evidence is limited on the efficacy of zirconia-based fixed dental prostheses. The purpose of this systemic review was to assess zirconia-based FDPs in terms of survival and complications. Searches performed in PubMed databases were enriched by hand searches to identify suitable publications. The keywords used were: "zirconia" and "fixed dental prosthesis," "zirconia" and "crown," "zirconia" and "fixed partial denture" and "humans," "zirconia" and "crown" and "humans," "crown" and "all-ceramics," and "fixed partial denture" and "all-ceramics". Titles and abstracts were read to identify literature that fulfilled the inclusion criteria. Only peer reviewed clinical studies published in the English language from January 1999 through June 2011 were included. Twelve clinical studies based on zirconia, framework design, and porcelain veneering technique met the inclusion criteria. Of the studies identified, 1 was a randomized clinical study with 3-year follow-up results; the others were cohort prospective studies. Clinical complications included chipping of veneering porcelain, abutment failure, and framework fracture. One study investigated pressed ceramics as the veneering material and found no chipping of veneering porcelain after 3 years. Short term clinical data suggest that zirconia-based fixed dental prostheses may serve as an alternative to metal ceramic fixed dental prostheses in the anterior and posterior dentition.