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The evaluation of external and internal implant/abutment connections

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Title: The evaluation of external and internal implant/abutment connections


1
The evaluation of external and internal
implant/abutment connections
2
  • Introduction
  • Implant/abutment connection
  • External connection
  • Internal connection
  • -Advantage
  • -Disadvantage
  • Selection of external/internal connection

3
Introduction
  • Long-term success of dental implants
  • - biologic factor, surgical procedure,
    restorative principles
  • Aesthetics, simplification of Tx.

4
Implant/abutment connection
  • Primary determinants of
  • Joint stability
  • Joint strength
  • Locational rotational stability
  • gt Prosthetic stability
  • ( Paul P. Binon 2000)

5
Implant/abutment connection
  • Original Branemark protocol
  • Fully edentulous pts. With fixed prosthesis
  • Coupling mech. For implant placement
  • - 0.7mm-tall external hexagon
  • - Only rotational torque transferring mechanism
    during the surgical placement
  • - not antirotational device for partial
    edentulous pts.

6
External connection
  • External hex-0.7mm standard hexagon
  • interchangeable in regular size platform

7
External connection-Advantages
  • Long term follow up data
  • Extensive use
  • Broad number of prescribed clinical application
  • Level of complication efforts to find solution

8
External connection- Disadvantages
  • Screw loosening
  • Mechanical failure
  • 0.7 mm ext hex 60-80Ncm antirotational
    resistance -gt hex height and width ?, tightening
    of fixture mount screw, pretapping for hard bone
  • Difficulty of abutment connection- short hex
  • Rotational misfit

9
External connection-Screw loosening
  • Jemt (1991), Becker and Becker (1995)
  • 40 screw loosening
  • (ext.connection single tooth restoration)
  • Levine (1999)
  • 3.6-5.3 screw loosening(conical implant
    abutment connection.)
  • Most often in sigle-tooth implant, molars

10
External connection-Screw loosening
  • Short,narrow ext. geometry
  • - limited engagement, short fulcrum point

11
External connection-Screw loosening
????? cantilever? ???? ??? ? ? fulcrum? ???? ????
????? ? ?? ? ???? ?? screw? ????? ?? hex? ???
?? ?? ? ?? ??? screw? ?? ???? screw loosening?
Force transfer mechanism In ext. hex system
12
External connection-Screw loosening
  • Implant diameter hex height?
  • ?screw loosening?
  • ???? ??? ????
  • ??? bending moment(F1 x C1)
  • ???? ??? bending
    moment(F2 x D1)
  • D1? ? F2?
  • ? ??? ???? ?? ????? screw? ???? ?? ????? screw
    loosening?

13
External connection-Screw loosening
  • Compensated by
  • Changing ext. hexagon - 1.2mm hex
  • Changing type of screw
  • Pan(flat) head seat, long stem length, 6 thread
    depth design gtmax. preload min. friction
    interference
  • Gold alloy screw, TorqTite (Teflon coating),
    Gold-Tite(pure gold coating) gt min. galling
    (adhesive wear)
  • Specific torque application
  • Precision of the fit over the hex

14
External connection-Rotational misfit
  • Freedom of fit- permits horizontal rotational
    movement to accommodate fitting error(Gyllenram
    F. 1994)
  • White(1993) horizontal fitting error ? screw
    deformation on tightening

Between implant hexagonal extension abutment
counterpart
15
External connection-Rotational misfit
  • Binon(1995)- 13? ext. hex implant test
  • machining specification ??
  • Rotational freedom-min 4?, Max 10.1?
  • Binon(1996)-?? ???? ?? ??? rotational freedom ??
  • Binon(1996)- 5???? rotational freedom? rapid
    screw loosening
  • 1.5 taper on hex, microstop on abutment
    hexagonal corner

16
Internal connection
  • New interface design
  • - To improve connection stability throughout
    function placement
  • - To simplify the armamentarium necessary for
    the clinician to complete the restoration

17
Internal connection
  • Friction fit
  • 8?taper(ITI, Avana, 3i TG, Ankylos)
  • 11?taper(Astra)
  • 2?Taper Rounded channel(Bicon)
  • Morse taper 6?, 8?(ITI, Swissplus, Implantium)
  • Passive fit
  • Internal hex(octa.Paragon)
  • Trichannel(Replace Select, Camlog)
  • Cam cylinder(Frialit-2)

18
Internal connection
19
Internal connection- Advantages
  • Screw loosening?
  • Convenience of abutment connection
  • Reduced vertical height platform for restorative
    components more esthetic
  • Distribution of lateral loading deep within
    implant, wall engagement with the implant that
    buffer vibration, potential for microbial seal

20
Internal connection- Screw loosening
?Cantilever? ???? ???? -Ext. hex ???? ?? screw?
????? ?? -int. con ?? screw? ???? ??? ?? ????
??? ???? ?? ??? ?? ???? ??? ????? ?? ?screw??
??? ?? ???? loosening? ?? ???? ??
21
Internal connection- Screw loosening
??? ??? ??? Internal lever arm? ??? ???? ???
???? ?? ?? ???? ??? ??? apex?? ???? ?? ????
???? ??? ?????? ???? ? ? ?? ???? ??? ??? ????
?????, screw loosening?
22
Internal connection-Low profile
????? head top?????(0.2mm) crown margin? ????? ??
metal showing ??
23
Internal connection-Internal hexagon(Paragon)
  • Slip-fit internal hexagon
  • friction fit
  • longer hex(1.5mm)
  • 1?taper male part
  • lead-in bevel
  • 3.5mm narrow configuration ??? ?? ???? ???(7? ???
    65.2 in Mn, 43.5 in Mx , De Bruyn 1999)

24
Internal connectionInternal cylinder
hex(Frialit-2)
  • Abutment screw? body?? 5mm ??
  • Mechanical test good strength, minimal
    rotation, superior screw stability, resistance to
    loosening, excellent machining tolerance(Binon
    1999)
  • Hex 60 indexing?? rotational resistance ??
  • Cylinder lateral load resistance, resistance to
    joint opening, protection of abutment screw, high
    strength value

25
Internal connectionCylinder cam/ Deep cam tube
  • Camlog(Altatec)tube-in- tube connection, Deep
    cylinder(5.4mm,upper lower internal thread),
    symmetric trichannel(1.2mm depth, 0.5 1.7??)
  • ??, ?? ??? ??, ?????
  • Replace Select(Nobel Biocare)
  • excellent lateral stability,easy seating

26
Internal connection-Cone screw tapered connection
  • 8? Morse taper(ITI, 3i TG, Avana)
  • tapered abutment post nonthreaded shaft
  • Internal tapered connection rationale
    mechanically locking friction fit, stable,
    self-locking interface
  • Short-profile octa abutment/ straight post
  • Sutter(1993) the ability of the conical portion
    of interface to absorb vibration functional
    load
  • ? no load to apical screw
  • 11?taper(Astra, Implantium)

27
Internal connection-Cone screw tapered connection
  • Morse taper type

ITI 3i TG Ankylos
Astra
28
Internal connectionTrue Morse tapered connection
  • Bicon(Boston, MA)
  • without any threaded component
  • 1? to 2?tapered post fits into smooth mirror
    image shaft
  • Dry clean abutment post implant shaft to secure
    the frictional resistance fit/ optimal resistance
    to dislodgement

29
An in vitro evaluation of the strength of an
internal conical interface compared to a butt
joint interface in implant design(Norton MR. COIR
1997)
  • Resistance to bending force

Biconical (Astra )
Standard butt joint (Branemark)
30
Material Methods
  • Astra (3.515, uniabutment, 8Ncm), Nobel
    biocare(3.7515, 7mm abutment, 15 Ncm)
  • Test1 resistance to 3-point bending at the
    fixture-abutment interface
  • Test2 resistance to 3-point bending at the
    abutment-bridge cylinder interface
  • 4mm from interface edge / Repeated 6times
  • 0.3mm permanent plastic deformation

31
Results
Test1. 3-point bending performance at
fixture-abutment interface joint Astra 1315 Nmm
/ Bra 645 Nmm moment Test2. Abutment-bridge
cylinder interface joint Astra 994Nmm / Bra
725Nmm moment ?Internal conical interface?
??????? bending force? ?? ???? ????? ???? ????
???? ?? ? ??
32
In vitro evaluation of strength of the conical
implant-to-abutment joint in two commercially
available implant system(Norton MR. JPD 2000)
  • ITI(8?taper), Astra(11?taper) conical joint?
    resistance to bending moment
  • 3-point bending test
  • 0.3mm permanent plastic deformation
  • - Astra(4.511) 4176Nmm/ ITI(4.114) 2526Nmm
  • ???? system ?? ????? ???? ??? ??? ????? ?? ?? ???

33
Mechanics of the implant-abutment connection An
8-degree taper compared to a butt joint
connection( Merz IJOMI 2000)
  • Understanding of 8-degree Morse taper/ butt joint
    mechanics
  • 12-mm ITI solid screw implant with 6-degree 7mm
    height abutment
  • 3-dimensional non-linear finite element model

34
Merz (2000)-Results
35Ncm tightening Morse taper symmetric, low
stress Butt joint Higher stress, clinically
acceptable
30 degree off-axis loading of 380N Morse
taperconical joint?? thread ??, Supporting
effect Butt jointtension side? stress ?,
abutment separated
35
Merz (2000)-Conclusion
  • Butt joint Only axial preload of abutment screw?
    stability of connection
  • - No lock? not absorb any lateral loading
  • Taper connection form lock friction ? lateral
    loading resistance
  • - reducing the load on the screw
  • - stable rotation- free connection

36
Comparision of strength and failure mode of seven
implant systems an vitro test (Mollersten JPD
1997)
  • The influence of joint depth on resistanace to
    bending forces
  • 7 implant system, 10 samples

Astra, ITI, Frialit-2, Impla-Med, Nobelpharma
Estheticone, IMZ titanium abutment, IMZ connector
37
Mollersten (1997)
  • Universal testing machine, compressive load
    0.1mm/s, perpendicular to long axis
  • Depth of failed joint? failure force?? ????? ????
    ??
  • Deep joint(IMZ Ti abut, Frialit-2)?? ?? ??

38
A vitro study of retained screw stability by
various connection designs between fixture and
abutment in implant dentistry(Jae-Sik Yang, JKAP
2004)
  • 5???? ????, ???, ????? ??? connection system? ??
    screw loosening? ??
  • 10?? ?? ??????
  • 3Hz ??, ?? 200N, 7400? ????? ??????

39
Jae-Sik Yang(2004)- Results
  • ?? ???
  • Ex1(94.88) ltIn4ltIn3ltIn2ltIn1(115.77)
  • ???? ???
  • In4(79.00)ltEx1ltIn3ltIn2ltIn1(94.63)
  • ?? ???? ???? ?? ???? cone screw?? beveled hex??
    ?? ???, ?????? ???? ???? ???? cone screw ?? ?? ??
    ?? ?????.

40
Internal connection- Disadvantages
  • Expensive, ??? ??
  • Screw type multiple implant ??? UCLA abutment ???
    ? ??
  • - ????? ??? ???? ??? abutment? ?? ??? ??? ??
    path of insertion? ??? ?
  • Screw type? ?? ??? screw loosening ???? external
    ? ??? ??

41
Internal connection- Disadvantages
?Screw type trausmucosal abutment? gold cylinder
???? ? ? ???? misfit (between gold cylinder
transmucosal abutment) ?gold screw loosening
Gold cylinder
Misfit
Transmucosal abutment
42
Selection of external/internal connection
system- Single implant
  • internal connection screw loosening ??? ??
  • external connection ????
  • - MD, BL width ???, Wide implant, zero degree
    rotation abutment, gold abutment
    screw(30-35Ncm),SCRP, Occlusal adjustment

43
Selection of connection system-Multiple implant
  • Screw-retained type
  • external type??
  • internal type?? ??? transmucosal abutment?????
    misfit? ?? gold screw loosening? ???? ??
  • ?? ???? ???? external type? ? ???

44
Selection of connection system-Multiple implant
  • Cement-retained type
  • - Screw loosening ?? internal type? ??
  • abutment? passive?? ???? ???? abutment? passive??
    ????? internal ?? external?? ???? passive fit ??
    ? ???? misfit? ?? screw loosening? ???? ??

45
Selection of connection system-Multiple implant
  • ?????? cantilever?? overloading
  • ????? external type ?? screw? load? ???? ???
    loosening? ?? ??
  • Internal type ??? ???? ?? fixture ??? ????? screw
    loosening? ??
  • ? ?? ?????? external ????? screw loosening? ?
    ???? ??
  • 3? ?? ????? splinting, cantilever ???,
    overload? ??? ??

46
Conclusion
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