Title: The evaluation of external and internal implant/abutment connections
1The evaluation of external and internal
implant/abutment connections
2- Introduction
- Implant/abutment connection
- External connection
- Internal connection
- -Advantage
- -Disadvantage
- Selection of external/internal connection
3Introduction
- Long-term success of dental implants
- - biologic factor, surgical procedure,
restorative principles - Aesthetics, simplification of Tx.
4Implant/abutment connection
- Primary determinants of
- Joint stability
- Joint strength
- Locational rotational stability
- gt Prosthetic stability
- ( Paul P. Binon 2000)
5Implant/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.
6External connection
- External hex-0.7mm standard hexagon
- interchangeable in regular size platform
7External connection-Advantages
- Long term follow up data
- Extensive use
- Broad number of prescribed clinical application
- Level of complication efforts to find solution
8External 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
9External 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
10External connection-Screw loosening
- Short,narrow ext. geometry
- - limited engagement, short fulcrum point
11External connection-Screw loosening
????? cantilever? ???? ??? ? ? fulcrum? ???? ????
????? ? ?? ? ???? ?? screw? ????? ?? hex? ???
?? ?? ? ?? ??? screw? ?? ???? screw loosening?
Force transfer mechanism In ext. hex system
12External connection-Screw loosening
- Implant diameter hex height?
- ?screw loosening?
- ???? ??? ????
- ??? bending moment(F1 x C1)
- ???? ??? bending
moment(F2 x D1) - D1? ? F2?
- ? ??? ???? ?? ????? screw? ???? ?? ????? screw
loosening?
13External 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
14External 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
15External 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
16Internal connection
- New interface design
- - To improve connection stability throughout
function placement - - To simplify the armamentarium necessary for
the clinician to complete the restoration
17Internal 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)
18Internal connection
19Internal 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
20Internal connection- Screw loosening
?Cantilever? ???? ???? -Ext. hex ???? ?? screw?
????? ?? -int. con ?? screw? ???? ??? ?? ????
??? ???? ?? ??? ?? ???? ??? ????? ?? ?screw??
??? ?? ???? loosening? ?? ???? ??
21Internal connection- Screw loosening
??? ??? ??? Internal lever arm? ??? ???? ???
???? ?? ?? ???? ??? ??? apex?? ???? ?? ????
???? ??? ?????? ???? ? ? ?? ???? ??? ??? ????
?????, screw loosening?
22Internal connection-Low profile
????? head top?????(0.2mm) crown margin? ????? ??
metal showing ??
23Internal 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)
24Internal 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
25Internal 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
26Internal 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)
27Internal connection-Cone screw tapered connection
ITI 3i TG Ankylos
Astra
28Internal 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
29An 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)
30Material 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? ?? ???? ????? ???? ????
???? ?? ? ??
32In 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 ?? ????? ???? ??? ??? ????? ?? ?? ???
33Mechanics 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
34Merz (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
35Merz (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
36Comparision 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
37Mollersten (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)?? ?? ??
38A 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? ????? ??????
39Jae-Sik Yang(2004)- Results
- ?? ???
- Ex1(94.88) ltIn4ltIn3ltIn2ltIn1(115.77)
- ???? ???
- In4(79.00)ltEx1ltIn3ltIn2ltIn1(94.63)
- ?? ???? ???? ?? ???? cone screw?? beveled hex??
?? ???, ?????? ???? ???? ???? cone screw ?? ?? ??
?? ?????.
40Internal connection- Disadvantages
- Expensive, ??? ??
- Screw type multiple implant ??? UCLA abutment ???
? ?? - - ????? ??? ???? ??? abutment? ?? ??? ??? ??
path of insertion? ??? ? - Screw type? ?? ??? screw loosening ???? external
? ??? ??
41Internal connection- Disadvantages
?Screw type trausmucosal abutment? gold cylinder
???? ? ? ???? misfit (between gold cylinder
transmucosal abutment) ?gold screw loosening
Gold cylinder
Misfit
Transmucosal abutment
42Selection 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
43Selection of connection system-Multiple implant
- Screw-retained type
- external type??
- internal type?? ??? transmucosal abutment?????
misfit? ?? gold screw loosening? ???? ?? - ?? ???? ???? external type? ? ???
44Selection of connection system-Multiple implant
- Cement-retained type
- - Screw loosening ?? internal type? ??
- abutment? passive?? ???? ???? abutment? passive??
????? internal ?? external?? ???? passive fit ??
? ???? misfit? ?? screw loosening? ???? ??
45Selection of connection system-Multiple implant
- ?????? cantilever?? overloading
- ????? external type ?? screw? load? ???? ???
loosening? ?? ?? - Internal type ??? ???? ?? fixture ??? ????? screw
loosening? ?? - ? ?? ?????? external ????? screw loosening? ?
???? ?? - 3? ?? ????? splinting, cantilever ???,
overload? ??? ??
46Conclusion