Clinical considerations of

biomechanics in
implantology
 Introduction
╺ The discipline of biomedical engineering, which applies
engineering principles to living systems, has unfolded a new
era in diagnosis, treatment planning, and rehabilitation in
patient care.

╺ Biomechanics uses the tools and methods of applied

engineering mechanics to search for structure-function
relationships in living materials.
2
 Biomechanics

 It is the relationship between the biologic behavior of oral

structures and the physical influence of a dental restoration.
(GPT-9)

3
Types of biomechanics

Reactive

Therapeutic
4
Definitions
╺ MASS: is the degree of gravitational attraction the body of
matter experiences.

╺ FORCE ( F) = ma; m = mass and a= acceleration.

╺ WEIGHT: is the gravitational force acting on an object at a

specified location.

5
╺ ELASTIC LIMIT : the maximum stress a material can
withstand before it becomes plastically deformed.

╺ YIELD STRENGTH: the stress required to produce a

given amount of plastic deformation

╺ ULTIMATE TENSILE STRENGTH: is the measure of

stress required to fracture a material

6
LOADS APPLIED TO DENTAL
IMPLANTS
Occlusal Passive
loads mechanical
loads

Perioral Non passive

forces prostheses
7
FORCE – CLINICAL LOADING
AXES
╺ A force applied to a dental implant rarely is directed absolutely
longitudinally along a single axis.
╺ Three clinical loading axes exist

Mesiodistal Faciolingual Occlusal

8
9
COMPONENTS OF FORCE

╺ A single occlusal contact most commonly result in a

three-dimensional occlusal force. The process by which
three-dimensional forces are broken down into their
component parts is referred to as vector resolution.

10
Compressive forces attempt to push masses
toward each other. Compressive forces tend to
maintain the integrity of a bone-to-implant interface

Tensile forces pull objects apart.

Shear forces on implants cause sliding forces.

11
12
╺ Forces acting on dental implants are referred to as vector
quantities.

MAGNITUDE DURATION DIRECTION TYPE

NATURE OF
MAGNIFICATION POSITION IN
OPPOSING
PROCESS ARCH
TEETH

13
MAGNITUDE
╺ Greater the force applied greater will the stresses developed around
the implant.

14
 DIRECTION
╺ Implant and the surrounding bone can best withstand
forces directed along the long axis of the implant…..

╺ Maxillary anterior implants are rarely placed along the

direction of occlusal forces.

╺ Mandibular molars are placed with a lingual inclination of

the implant body
15
TYPES

16
DURATION
 The perioral muscles also apply a constant yet light
horizontal force on the teeth and implants.

 Parafunctional habits significantly increase the

duration of these loads

17
FORCE MAGNIFIERS

╺ The magnitude of the force may be decreased by

reducing the significant magnifiers of force:-

CANTILEVER OFFSET CROWN

LENGTH LOADS HEIGHT

18
 ╺ Screw loosening increases with increasing abutment angulation and collar
length after 100,000 cycles of dynamic cyclic loading.
╺ Results of this study showed that conical hybrid connection design
provides more biomechanically stable screw joint with straight abutments
than angled abutments.

El-Sheikh MA, Mostafa TM, El-Sheikh MM. Effect of different angulations and collar lengths of conical
hybrid implant abutment on screw loosening after dynamic cyclic loading. International journal of
19
implant dentistry. 2018 Dec 1;4(1):39.
STRESS
╺ The manner in which a force is distributed over a surface
is referred to as mechanical stress.

╺ Stress = F/A

╺ The internal stresses that develop in an implant system

and surrounding biologic tissues have a significant
influence on the long-term longevity of the implants in
vivo. 20
The magnitude of stress is dependent on two variables:-

1. Force magnitude and

2. Cross-sectional area over which the force is
dissipated.

21
FORCE REDUCTION
STRATEGIES
╺ Night guards to decrease nocturnal parafunction

╺ Occlusal materials that decrease impact force

╺ Overdentures rather than fixed prosthesis so

they may be removed at night

22
FUNCTIONAL CROSS SECTIONAL
AREA
╺ Surface that participates significantly in load bearing and stress
dissipation.
╺ This area may be optimized by

(1) Increasing the number of implants for a given edentulous site

(2) selecting an implant geometry that has been designed carefully to
maximize functional cross-sectional area.

23
╺ An increase in functional surface area serves to
decrease the magnitude of mechanical stress imposed
on the prosthesis, implant, and biological tissues.

24
 DEFORMATION AND STRESS
╺ The deformation and stiffness characteristics of the materials used
in implant dentistry, particularly the implant materials, may
influence interfacial tissues, ease of implant manufacture, and
clinical longevities.

╺ Elongation (deformation) of biomaterials used for surgical dental

implants ranges from 0 for aluminum oxide ceramics to up to 55
for annealed 316 L stainless steel.

╺ Related to deformation is the concept of strain, a parameter

believed to be a key mediator of bone activity
25
26
27
STRESS STRAIN RELATIONSHIP
╺ A relationship is needed between the applied force (and
stress) and the subsequent deformation (and strain).

╺ If any elastic body is experimentally subjected to an

applied load, a load-vs.-deformation curve may be
generated.

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29
╺ Such a curve provides for the prediction of how much
strain will be experienced in a given material under the
action of an applied load.

╺ The slope of the linear (elastic) portion of this curve is

referred to as the modulus of elasticity (E), and its value
indicates the stiffness of the material under study.

30
 The closer the modulus of elasticity of the implant
resembles that of the biologic tissues, the less the
likelihood of relative motion at the tissue-to- implant
interface.

 Once a particular implant system (i.e., a specific

biomaterial) is selected, the only way to control the strain is
to control the applied stress or change the density of bone
around the implant.

31
 IMPACT LOAD
When two bodies collide in a very small interval of time
(fractions of a second), relatively large forces develop. Such a
collision is described as impact.

In dental implant systems subjected to occlusal impact loads,

deformation may occur in
╺ The prosthetic restoration,
╺ In the implant itself, or
╺ In the interfacial tissue
32
• The higher the impact load, the greater the risk of implant
and bridge failure and bone fracture.

• Rigidly fixed implants generates a higher impact force

than a natural tooth with its periodontal ligament.

 Various methods have been proposed to address the

issue of reducing implant loads

33
Skalak suggested the use of acrylic teeth in conjunction with
osteointegrated fixtures. (JPD ; June 1983, vol 49)

Weiss has proposed that a fibrous tissue-to-implant

interface provides for physiologic shock absorption in the
same manner as by a functioning periodontal ligament.

Misch advocates an acrylic provisional restoration with a

progressive occlusal loading to improve the bone-implant
interface before the final restoration, occlusal design, and
masticatory loads are distributed to the system

34
FORCE DELIVERY AND
FAILURE MECHANISM
•The manner in which forces are applied to implant
restorations dictates the likelihood of system failure.

•If a force is applied some distance away from a weak link in

an implant or prosthesis, bending or torsional failure may
result from moment loads.

35
 ╺ MOMENT LOADS
╺ The moment of a force about a pointtends to produce
rotation or bending about that point.

╺The moment is a vector quantity.

╺ Moment Loads = force magnitude X moment arm

╺This imposed moment load is also referred to as a torque or

torsional load and may be quite destructive with respect to
implant systems.
36
CLINICAL MOMENT ARMS

37
╺A total of six moments (rotations) may develop about the
three clinical coordinate axes.

╺Such moment loads induce microrotations and stress

concentrations at the crest of the alveolar ridge at the implant-
to- tissue interface, which leads to crestal bone loss.

╺Three "clinical moment arms" exist in implant dentistry:-

OCCLUSAL CANTILEVER OCCLUSAL

HEIGHT LENGTH WIDTH

38
OCCLUSAL HEIGHT
╺ Occlusal height serves as the moment arm for force
components directed along the faciolingual axis as well
as along the mesiodistal axis.

39
╺ Moment of a force along the vertical axis is not affected by
the occlusal height because there is no effective moment
arm. Offset occlusal contacts or lateral loads, however, will
introduce significant moment arms.

40
╺ Under nonaxial forces, increased CHS does not influence the
decrease in screw load or increase in member load. However, it
contributes to screw loosening and fatigue fracture by skewing
the stress distribution to the transverse section of the implant

Bulaqi HA, Mashhadi MM, Safari H, Samandari MM, Geramipanah F. Effect of increased
crown height on stress distribution in short dental implant components and their surrounding
bone: A finite element analysis. The Journal of Prosthetic Dentistry. 2015 Jun 1;113(6):548- 41
57.
CANTILEVER LENGTH
• Large moments may develop from vertical axis force
components in cantilever extensions or offset loads
from rigidly fixed implants.

• A lingual force component may also induce a twisting

moment about the implant neck axis if applied through
a cantilever length.
42
 Effects of Cantilever Length and Implant Inclination
on the Stress Distribution of Mandibular Prosthetic
Restorations Constructed from Monolithic Zirconia
Ceramic

╺ It was concluded that cantilever length and implant inclination affected the
distribution of force.
╺ Increase in cantilever length led to reduction in stress values in distally
tilted posterior implants.
╺ Increase in distal inclination led to reduction in stress values in distally
titled posterior implants and cortical bone tissue in the model with a short
cantilever.

Durkan R, Oyar P, Deste G. Effects of Cantilever Length and Implant Inclination on the Stress
Distribution of Mandibular Prosthetic Restorations Constructed from Monolithic Zirconia
Ceramic. International Journal of Oral & Maxillofacial Implants. 2020 Jan 1;35(1). 43
• A 100-N force applied directly over the implant does not induce a
moment load or torque because no rotational forces are applied
through an offset distance.

• This same 100-N force applied 1 cm from the implant results in a

100 N-cm moment load.

• Similarly, if the load is applied 2 cm from the implant, a 200 N-cm

torque is applied to the implant-bone region, and 3 cm results in a
300 N-cm moment load.

╺ (Implant abutments are typically tightened with less than 30

N-cm of torque).
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 A-P DISTANCE
 The distance from the center of the most anterior
implant to the distal of each posterior implant is called
the anteroposterior (AP) distance.

 The greater the A - P distance, the smaller the

resultant load on the implant system from cantilevered
forces, because of the stabilizing effect of the
anteroposterior distance.

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╺ According to Misch, the amount of stress applied to the
system determines the length of this distal cantilever.

╺ Because stress equals force divided by area, both aspects

must be considered.

╺ The magnitude and direction of force are determined by

parafunction, crown height, masticatory dynamics, gender,
age, and arch location.

46
╺ The most ideal biomechanical arch form depends on the
restorative situation:-
• Tapering arch form is favorable for anterior implants with
posterior cantilevers.
• Square arch form is preferred when canine and posterior implants
are used to support anterior cantilevers in either arch.

• Ovoid arch form has qualities of both tapered and square arches.

╺ Clinical experiences suggest that the distal

cantilever should not extend 2.5 times the A-P distance under
ideal conditions.

• Patients with severe bruxism should not be 47

restored with any cantilevers.
╺ The maxilla has less dense bone than the mandible and
more often has an anterior cantilever with the prosthesis.

╺ As a result, more distal implants may be required in the

maxilla to increase the A-P spread for the anterior or
posterior cantilever than in the mandible

╺ sinus augmentation may be required to permit posterior

placement of the implant.

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OCCLUSAL WIDTH

 Wide occlusal tables increase the moment arm for any

offset occlusal loads.

 Faciolingual tipping (rotation) can be significantly reduced

by narrowing the occlusal tables and/or adjusting the
occlusion to provide more centric contacts

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╺ A vicious, destructive cycle can develop with moment
loads and result in crestal bone loss.

INCREASE IN
ROCKIN AND
CRESTAL
MORE
BONE LOSS
CRESTAL
BONE LOSSG

FACIOLINGUAL INCREASE IN
MICRO OCCLUSAL
ROTATION HEIGHT

50
 FATIQUE FAILURE
╺ FATIGUE FRACTURE: Continuous forces on a certain material, results

in internal deformation which after a certain amount results in

permanent deformation or fracture.

FORCE NUMBER OF
BIOMATERIAL FACTOR CYCLES

GEOMETRY
51
Biomaterial
Stress level below which an implant biomaterial can be
loaded indefinitely is referred as endurance limit.
Ti alloy exhibits high endurance limit compared with pure
Ti.

Number of cycles
 Loading cycles should be reduced.

 Eliminate parafunctional habits.

 Reduce occlusal contacts.

52
Implant geometry

 should resist bending & torsional load .

 Related to metal thickness.
2 times thicker in wall thickness – 16 times stronger.

Force magnitude

 Arch position( higher in posterior & anterior)

 Eliminate torque
 Increase in surface area

53
 MOMENT OF INERTIA
╺ Moment of inertia is an important property of cylindrical implant design
because of its importance in the analysis of bending and torsion.
╺ The bending stress in a cylinder is given by the following equation:

s =My/I

╺ M is moment (newton-centimeters),
╺ y is the distance from the neutral axis of bending (centimeters),
╺ I is the moment of inertia (centimeters to the fourth power)

54
╺ The bending stress (and likelihood of bending fracture)
decreases with increasing moment of inertia.

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BIOMECHANICAL
PRINICIPALS

56
 IMPLANT DESIGN

MACRO DESIGN MICRODESIGN

57
FORCE TYPE AND INFLUENCE
ON IMPLANT BODY DESIGN

COMPRESSIV STRONGEST
E

TENSILE 35%
WEAKER

SHEAR 65% WEAKER

58
59
 IMPLANT
MACROGEOMETRY
 Smooth sided cylindrical implants – subjected to shear forces

 Smooth sided tapered implants – places compressive load at

interface

 Tapered threaded implants- compressive load to bone

 Greater the taper – greater the compressive load delivery

60
Bolind et al- compared cylinder implants with
threaded implants from functioning prosthesis
╺ Greater BIC was found in threaded implant
╺ Greater marginal bone loss was observed around cylinder
implants.
╺ Cylinder implants had roughened surface condition but still
bone loss was observed.
╺ Hence implant body design is more important than surface
condition.

61
62
FORCE DIRECTION AND
INFLUENCE ON IMPLANT BODY
DESIGN

╺ Bone is weaker when loaded under an angled load.

╺ A 30 degree angled load increases overall stress by 50%.

╺ Implant body long axis should be perpendicular curve of wilson

and Spee to apply long axis load

63
 ╺ The stress values were higher in the angled implant-supported crown
than in the straight one; and in the model with oblique loading forces than
with vertical ones, for both the titanium structures and the zirconia
frameworks.

╺ Zirconia frameworks showed higher stress values than the titanium

structures because of the high elastic modulus of zirconia
Guven S, Atalay Y, Asutay F, Ucan MC, Dundar S, Karaman T, Gunes N. Comparison of the effects
of different loading locations on stresses transferred to straight and angled implant-supported
zirconia frameworks: a finite element method study. Biotechnology & Biotechnological Equipment. 64
2015 Jul 4;29(4):766-72.
 FUNCTIONAL V/S THEORETICAL
SURFACE AREA
╺ Plasma spray coating provide 600% more of TSA.

╺ Bone cell does not receive a transfer of mechanical stress

from this feature.

╺ The amount of actual BIC that can be used for

compressive loading < 30% of TSA.

╺ Increase in length or diameter of implant causes increase

in FSA 65
 Implant length

╺ Increase in length –Bi cortical stabilization

╺ Maximum stress generated by lateral load can be dissipated

by implants in the range of 10-15mm

╺ Sinus grafting & nerve re-positioning to place greater implant

length

66
Implant width
╺ Increase in implant width – increases functional surface area
of implant

╺ Increase in 1mm width – increase in 33% of functional

surface area

╺ Wider diameter implants reduce the likelihood of component

fracture in dental implants

67
╺ Narrow diameter implants placed in both narrow and average ridge width
models demonstrated higher stress to the model than standard or wide
diameter implants placed in ridges with narrow and average buccal-lingual
width.
╺ It may be that the volume and quality of bone surrounding implants likely
influences stress distribution with a greater cortical to trabecular bone ratio
providing better support.
╺ Wide diameter implants demonstrated the least stress to the model as
compared to narrow and standard diameter implants with the least stress
being distributed in the average ridge as compared to the narrow ridge.

Termeie D, Klokkevold PR, Caputo AA. Effect of implant diameter and ridge dimension on
stress distribution in mandibular first molar sites—A photoelastic study. Journal of Oral
Implantology. 2015 Oct;41(5):e165-73. 68
IMPACT OF IMPLANT SHAPE ON STRESS
DISTRIBUTION

╺ Endosteal dental implant designs may be generally

considered as blade or root form.

╺ When viewed from the broad end, blade implants show a

relatively favorable stress pattern,

╺ when viewed from the front - extremely unfavorable stress

pattern - horizontal forces.
69
IMPACT OF IMPLANT SHAPE ON STRESS
DISTRIBUTION

╺ Blade implants are designed to serve in those bony sites which are too
narrow to accommodate root form implants.

╺ They have reduced cross-sectional area available to resist axial loads

as compared to root form implants.

╺ Perforations or "vents" serve to increase the amount of cross-sectional

area available to resist axial loads

70
 Thread geometry
 Maximize initial contact.

 Enhance surface area

 Facilitate dissipation of loads at the bone implant

interface.

 FSA can be modified by varying three thread parameters:

Thread pitch, thread shape and thread depth

71
Thread pitch
╺ Thread pitch is the distance measured parallel between adjacent thread form
features of an implant.

╺ The length of the threaded portion of the implant body divided by the pitch
equals the threads per unit length.

╺ The smaller (or finer) the pitch, the more threads on the implant body for a
given unit length and thus the greater surface area per unit length of the implant
body if all other factors are equal.

72
73
╺ Effects of the implant thread pitch on the maximum stresses were evaluated
in jaw bones and implant– abutment complex by a finite element method.

╺ The thread pitch ranged from 0.5 mm to 1.6 mm.

╺ When thread pitch exceeded 0.8 mm, minimum stresses were obtained.

╺ Cancellous bone was more sensitive to thread pitch than cortical bone did.

74
 Thread shape

V Reverse
shaped buttress

Square Buttress
thread thread

75
76
╺ V shaped threads convert the primary compressive
forces to the and result in 30 degree angled load

╺ Square shaped threads are more resistant to a shear

load.

77
╺ Maximum stresses were seen at the cortical bone and were
transferred to the implant.
╺ Minimum Von Mises stresses were seen with reverse buttress
thread design at the cortical bone.
╺ The stresses were observed least at the cancellous bone and
maximum at the implant.
Oswal MM, Amasi UN, Oswal MS, Bhagat AS. Influence of three different implant thread
designs on stress distribution: A three-dimensional finite element analysis. The Journal of
the Indian Prosthodontic Society. 2016 Oct;16(4):359. 78
 Thread depth
╺ Greater the thread depth
,greater the surface area of the
implant.
╺ Thread depth is most in v shaped
threads
╺ As the diameter increases , thread
depth also increases
╺ Thread depth can be modified along
with diameter of implant to increase
the TSA by 150% for every 1mm
increase in diameter.
79
 Crest module design
 Should be slightly larger than outer diameter of the implant
1. to completely seal the osteotomy site
2. Seal provides for greater initial stability
3. Increase FSA thereby reducing stress at the crestal region.

 Height should be sufficient to provide biologic width

80
╺ Smooth parallel sided crest –
shear stress.
╺ Angled crest module less
than 20 degree-
╺ -Increase in bone contact
area
╺ -Beneficial compressive load
╺ Larger diameter than outer
thread diameter
╺ -Prevents bacterial ingress
╺ -Initial stability
╺ -Increase in surface area

81
82
 Apical design
╺ Round cross-section do not resist torsional load
╺ Incorporation of anti – rotational feature
╺ Vent\ hole- bone grows into it
╺ Resist torsion
╺ Flat side\groove - bone grow against it.

83
84
 ╺ FEA revealed that great sudden changes in diameter along the fixture increases
stress and strain in peri-implant bone. Therefore, uniform tapering should be
considered as a standard feature for most clinical situations, and a flat apical
design, which creates a better stress and strain distribution in surrounding bone
than dome-shaped bone, should also be used

Kadkhodazadeh, M., Lafzi, A., Raoofi, S., Khademi, M., Amid, R., Movahhedy, M.R. and Torabi,
H., 2014. Comparison of the effects of different implant apical designs on the magnitude and
distribution of stress and strain in bone: a finite element analysis study. Journal of long-term
effects of medical implants, 24(2-3). 85
IMPLANT BODY BIOMATERIAL
RELATED TO FRACTURE
Modulus of elasticity
optimal
Vitreous carbon Ultimate strength not
adequate

• Ultimate strength
adequate
Ceramic • Modulus of elasticity
33 times stiffer

• Closest approximation
of modulus of
Titanium
elasticity
• Ultimate strength 86
adequate
 TITANIUM

TI-6AL-4V
CP TITANIUM
ALLOY

╺ Titanium alloy is 4 times stronger than CP titanium

╺ The fatigue strength is also 4 times stronger than CP titanium

87
 ╺ This study has demonstrated that the importance of different implant biomaterial
such as zirconia and compared with that of titanium.
╺ Similar stress and deformation pattern in bone were observed. Hence, Zirconia
(Y-PSZ) implants can be used as an alternative in individuals who shows allergy
to titanium and as an esthetic implant biomaterial

Amtul Haseeb S, Abdul Khader SM, Satish Shenoy B, Naveen YG, Giridhar Kamath P, Vinaya
KC. Comparative evaluation of stress distribution in bone surrounding implant using different
implant biomaterials: A 3DFEA study. Journal of Computational Methods in Sciences and 88
Engineering. 2019 Jan 1;19(2):523-32.
Bone response to mechanical load
 Bone responds to number of factors including systemic
and mechanical forces.

 Cortical and trabecular bone are modified by modelling

and remodelling Controlled by mechanical environment
of strain.

89
Frost zones of microstrain

90
 Pathologic overload zone and acute disease window are the
two extremes of the strain conditions.

 Each of these conditions result in less bone.

 Higher BRR - Increased woven bone formation.

 Mild overload zone - Higher BRR - Increases

woven bone formation

 The adapted window zone is most likely to be organized,

highly mineralized, lamellar bone.

 It is the ideal strain condition next to a dental implant,

91
 CONCLUSION
╺ The most common complications in implant-related reconstruction
are related to biomechanical conditions.

╺ Implant healing failures may result from micromovement of the

implant from too much stress.

╺ Early crestal bone loss may be related to occlusal overload

conditions.

╺ The manifestation of biomechanical loads on dental implants

(moments, stress, and strain) controls the long-term health of the
bone. 92
References
╺ Contemporary implant dentistry -Carl E Misch Ed 3rd
╺ Basic bio-mechanics of dental implants in prosthetic dentistry J Prosthet Dent
1989; 61:602-609
╺ Amtul Haseeb S, Abdul Khader SM, Satish Shenoy B, Naveen YG, Giridhar
Kamath P, Vinaya KC. Comparative evaluation of stress distribution in bone
surrounding implant using different implant biomaterials: A 3DFEA study. Journal
of Computational Methods in Sciences and Engineering. 2019 Jan 1;19(2):523-32
╺ Kadkhodazadeh, M., Lafzi, A., Raoofi, S., Khademi, M., Amid, R., Movahhedy,
M.R. and Torabi, H., 2014. Comparison of the effects of different implant apical
designs on the magnitude and distribution of stress and strain in bone: a finite
element analysis study. Journal of long-term effects of medical implants, 24(2-3).

93
╺ Oswal MM, Amasi UN, Oswal MS, Bhagat AS. Influence of three
different implant thread designs on stress distribution: A three-
dimensional finite element analysis. The Journal of the Indian
Prosthodontic Society. 2016 Oct;16(4):359
╺ Termeie D, Klokkevold PR, Caputo AA. Effect of implant diameter and
ridge dimension on stress distribution in mandibular first molar sites—A
photoelastic study. Journal of Oral Implantology. 2015 Oct;41(5):e165-
73
╺ Guven S, Atalay Y, Asutay F, Ucan MC, Dundar S, Karaman T, Gunes N.
Comparison of the effects of different loading locations on stresses
transferred to straight and angled implant-supported zirconia
frameworks: a finite element method study. Biotechnology &
Biotechnological Equipment. 2015 Jul 4;29(4):766-72.

94
╺ Durkan R, Oyar P, Deste G. Effects of Cantilever Length and Implant
Inclination on the Stress Distribution of Mandibular Prosthetic
Restorations Constructed from Monolithic Zirconia Ceramic. International
Journal of Oral & Maxillofacial Implants. 2020 Jan 1;35(1).
╺ Bulaqi HA, Mashhadi MM, Safari H, Samandari MM, Geramipanah F.
Effect of increased crown height on stress distribution in short dental
implant components and their surrounding bone: A finite element analysis.
The Journal of Prosthetic Dentistry. 2015 Jun 1;113(6):548-5
╺ El-Sheikh MA, Mostafa TM, El-Sheikh MM. Effect of different angulations
and collar lengths of conical hybrid implant abutment on screw loosening
after dynamic cyclic loading. International journal of implant dentistry.
2018 Dec 1;4(1):39.

95