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Thommen Implant System Implant/Abutment ConnectionStart with a Solid Connection
SWISS PRECISION AND INNOVATION. SWISS PRECISION AND INNOVATION.
Thommen Implant SystemImplant/Abutment ConnectionStart with a Solid Connection
The implant/abutment connection lies
at the heart of any implant system. At
the present time there are more than
twenty different implant/abutment
c onnections on the market, some of
which meet the various requirements
better than others. This paper presents
an overview of how divergent
requirements for an implant/abutment
connection can be combined to
provide a superior esthetic solution
without compromising long-term
reliability.
The requirements for an optimal
implant/abutment connection can be
summarized as follows:
· Minimum platform height for optimal
prosthetic flexibility
· Accurate transfer of the implant
position to the master model
· Precise rotational orientation for
single-tooth restorations
· Maximum mechanical stability
· Optimal fatigue resistance
· Minimized microgap
· Overload protection
The Thommen Implant System
implant/abutment connection was
developed more than twenty years
ago and has proved itself decisively
since. The implant/ abutment
connection of The Thommen Implant
System was one of the first to have an
internal hexagon. Internal connections
have a great advantage over external
connections in that they allow a longer
engaging surface while reducing the
platform height of the implant, which
allows more flexibility in designing the
emergence profile of the final
restoration.
The internal hexagon of The Thommen
Implant System is manufactured with
the highest precision and allows an
extremely accurate transfer of the
implant position to the master model,
which in turn ensures a perfect fit for
the prosthesis. The internal hexagon
also provides precise rotational
orientation and stability for single-tooth
implant restorations thanks to the
large, indexed contact surfaces1.
A unique feature of The Thommen
Implant System implant/ abutment
connection is the reinforcement collar
3
2
1
on the implant platform. This carries the
bulk of non-axial forces and gives
optimal mechanical stability to the
implant/ abutment connection. Further,
the reinforcement collar helps to isolate
the abutment screw from lateral forces
which could otherwise contribute to
screw loosening.
Fig. 1:
The Thommen Implant System
implant/abutment connection:
1 Reinforcement collar
· optimal mechanical stability
· focused compression for minimal
microgap
2 Internal hexagon
· minimal height for prosthetic flexibility
· rotational stability for single-tooth
implant restorations
· accurate impression transfer
3 FEM-optimized wall dimensions
· optimal fatigue resistance
2 © Thommen Medical
© Thommen Medical 3
Finally, the reinforcement collar focuses
the contact area between the implant
and abutment, so that there is higher
surface compression in the critical
perimeter area of the connection with
comparatively modest torque used on
the abutment screw. This mini mizes
the microgap between the implant and
abutment which in turn reduces the
occurrence of bacterial
contamination2.
In determining the design of an internal
connection, particular attention has to
be paid to the strength of the implant
walls: they must be able to withstand
significant torque loads placed on the
connection during surgical insertion as
well as strong occlusal forces without
fear of deformation or fracture. For this
reason, the dimensions of The
Thommen Implant System implant/
abutment connection were calculated
and optimized using the finite element
method, and thoroughly tested on our
in-house hydropulser equipment to
ensure optimal strength and fatigue
resistance.
All Thommen Implant System
components are subjected to strict
testing in accordance with ISO 14801.
This dictates dynamic strength testing
parameters of 2 million loading cycles at
a frequency of 2 Hz in a saline solution
with a temperature of 37º C (to
replicate the oral cavity).
In the FEM images, the color scale
indicates the level of stress – with blue
the lowest and red the highest. During
the design optimization process,
modifications are made and test ed
until the ideal distribution of stress –
and hence strength – is obtained.
Fig. 2:
Design optimization with FEM analysis
4 © Thommen Medical
Fig. 3:
Test set-up for implants and prosthetic
parts according to ISO 14801
Fig. 4:
In-house laboratory for fatigue testing
Fatigue testing (ISO 14801)
10 mm
Specimen holder
PMMA
Implant
Normal bone level(no bone resorption)
Abutment
Gold coping
Simulated crown
F
5 mm
Load F [N] Runout 2 3 106 cycles
F30º
Specimen holder
PMMA
Implant
Abutment
Gold copingSimulated crown
Load rod
11 mm 8 mm
3 mm
Bone resorption
Runoutload
Lo
ad
F [
N]
3 3
1 3
Test conditionsFrequency 2 HzRunouts 2 3 106 cyclesEnvironment 0.9 % NaCI/37º C
© Thommen Medical 5
The Thommen abutment screw
Fig. 5:
1 Small screw head
narrow screw channel/better
esthetics
2 Conical screw seat
to prevent loosening of the screw
3 Reduced diameter shaft
for optimal fatigue resistance
Predesigned breakage point
for overload protection
The abutment screw plays a central
role for the mechanical strength and
optimal fatigue resistance of The
Thommen Implant System implant/
abutment connection. To begin, let us
summarize the requirements of an
ideal abutment screw:
· Minimal head diameter
· No loosening
· Optimal fatigue resistance
· Overload protection
· Excellent pick-up and carrying ability
The abutment screw of The Thommen
Implant System has a small screw head
– with a diameter of 1.6 mm respectively
1.9 mm compared with more typical
diameters of 2.2 mm to 2.6 mm. The
small screw head is possible because it
does not need to withstand the higher
clamping forces which other designs
may require (typically 35 Ncm) and it is
protected from non-axial loads by the
reinforcement collar discussed
previously. The small screw head
allows The Thommen Implant System
abutments to be produced with a
narrower screw channel and thicker
walls. This in turn gives the dental
technician more freedom for prosthetic
design and fabrication for a strong and
esthetic result.
One typical complication of implant/
abutment connections is that the
screw may loosen3,4. This is caused by
non-axial forces that may lead to
relative motions between screw head
and abutment5. The abutment screw
of The Thommen Implant System has a
conical screw seat (conical angle of
60°) that precludes such relative lateral
motions and minimizes the risk of the
screw becoming loose. The same
concept has been used for decades in
the car industry to keep wheel lug nuts
tight. Tests on the hydropulser
Fig. 6:
Wheel of a car with the same concept
of a conical screw seat
equipment has shown that after 2
million load cycles no change in the
abutment screw’s tighten ing torque
could be observed.
The abutment screw utilizes a proven
reduced diameter shaft (anti-fatigue
shaft)6, a common component in
engineering that is used in the design
of connections that are subject to
strong dynamic loads7. An anti-fatigue
shaft screw differs from a normal
screw in that the shaft is subject to
deformation when exposed to tension
and acts like a spring. Tightening the
abutment screw imparts a calculated
amount of tension (“pre-load”) on the
shaft which compresses the abutment
onto the implant to generate a stable
connection. The appropriate pre-load
of the abutment screw is attained by
the application of the correct tightening
torque. For the reasons described
above, the required torque is lower
than that used with many other implant
systems. It is important not to exceed
the specified torque, because this
places excessive pre-load on the shaft
and actually prevents it from
functioning properly.
1
3
2
6 © Thommen Medical
In addition to its physical design,
optimal fatigue properties of The
Thommen Implant System abutment
screw are ensured by the use of a
high-strength titanium alloy. The
selected titanium alloy has excellent
biocompatibility and is widely used in
orthopedic devices8,9.
The Thommen Implant System
abutment screw also serves as the
pre-designed breakage point for the
implant/abutment connection. This
minimizes the risk of damaging the
implant should the prosthetic be
exposed to an overload, which may
occur, for example during an accident.
Prosthetic components may be
repaired or replaced relatively easily,
but it is critical that the implant be
protected in such an event. The
optimal breakage point was
determined through careful FEM
analysis and thorough testing on the
hydropulser equipment.
Finally, convenient and safe handling is
an important design requirement for an
abutment screw. The Thommen
Implant System abut ment screw
satisfies this requirement with its
unique 4-lobe head design. The 4-lobe
head is specially tapered to allow easy
and secure pick-up of both abutment
screw sizes using a single screwdriver.
Further, the 4-lobe head is more
resistant to deformation than a
comparably sized hexagon.
Conclusion
The Thommen Implant System implant/
abutment connection, combined with
The Thommen Implant System
abutment screw, offers an ideal
balance of reliability, safety and
esthetics.
· Minimum platform height and head
diameter for optimal prosthetic
flexibility and excellent esthetic
results.
· Tight tolerances and precise
production methods ensure an
extremely accurate transfer of the
implant position to the master
model, which in turn ensures a
perfect fit for the prosthesis.
· Internal hexagon provides precise
rotational orientation and stability for
single-tooth implant restorations
thanks to the large, indexed contact
surfaces.
· High surface compression in the
critical perimeter area of the
connection results in a minimal
microgap between the implant and
the abutment, which in turn reduces
the occurrence of bacterial
contamination.
· Optimal mechanical stability and
fatigue resistance thanks to a
superior design and durable
material.
· Built-in protection from screw
loosen ing with proven design
techniques.
· Easy and convenient handling.
With over twenty-five years of proven
results, The Thommen Implant System
implant/abutment connection and
abutment screw is indeed a solid
connection on which to build a lasting,
beautiful restoration.
Zusammenfassung
Im vorliegenden Artikel wird die Funktion der
Implantat/Abutment-Verbindung des Thommen Im-
plantatsystems eingehend beschrieben.
Die Verbindung zwischen Implantat und Abutment
ist eines der wichtigsten Elemente eines Implantat-
systems. Es werden verschiedene Anforderungen
an die Funktion gestellt wie minimale Bauhöhe
für prothetische Flexibilität, präzise Passungen,
optimale Ermüdungsfestigkeit etc. Um eine
bestmögliche Lösung anzubieten, kommt beim
Thommen Implantatsystems eine Innenverbindung,
ergänzt mit einem Führungsring, zum Einsatz. Die In-
nenverbindung ist mit einem Sechskant zur Rotati-
onssicherung ausgebildet und weist im Vergleich zur
Aussenverbindung eine längere Führung des Abut-
ments auf. Diese Führung ist ausschlaggebend für
die Stabilität.
Eine Besonderheit des Thommen Implantatsystems
ist der Führungs ring: Dieser schützt die Abutment-
schraube vor nicht axialen Kräften und verhindert
eine Schraubenlockerung. Zusätzlich wird durch den
Führungsring die Auflagefläche zwischen Implantat
und Abutment reduziert, wodurch bei gleichem
Anzugsmoment eine höhere Flächenpressung und
somit eine bestmögliche Abdichtung gegen Körper-
flüssigkeiten ermöglicht wird.
Die Abutmentschraube hat einen kleinen Schrau-
benkopf, damit ein dünner Schraubenkanal ermögli-
cht wird. Dies ist für eine optimale ästhetische
Versorgung notwendig. Die optimalen
Eigenschaften gegen Ermüdung der Abutment-
schraube werden einerseits durch das Design einer
klassischen Dehnschaft schraube, wie sie im traditio-
nellen Maschinenbau für dynamisch hoch belastete
Verbindungen verwendet wird, andererseits durch
die Verwendung einer hochfesten Titanliegierung
ermöglicht.
Das Thommen Implantatsystems wurde mittels
FEM- Berechnungen optimiert und die
Ermüdungsfestigkeit ausgiebig getestet. Dabei
wurde das System so ausgelegt, dass im Falle einer
Über belastung, wie zum Beispiel bei einem Unfall,
die Abutmentschraube als Soll bruchstelle agiert und
somit das Implantat vor einer Beschädigung schützt.
© Thommen Medical 7
1 Binon PP. The Effect of Implant/Abutment Hexagonal Misfit on Screw Joint Stability. Journal of Prosthodontics Vol. 9, 1996; 149–160
2 Steinebrunner L, Worfart S, Bössmann K, Kern M. In Vitro Evaluation of Bacterial Leakage Along the Implant-Abutment Interface of Different Implant Systems.
JOMI Vol. 20, Number 6; 2005; 875–881
3 Jung RE, Pjetursson BE, Glauser R, Zembic A, Zwahlen M, Lang NP. A systematic review of the 5-year survival and complication rates of implant supported
single crowns. Clin. Oral Impl. Res.19, 2008; 119–130
4 Kreissl ME, Gerd T, Muche R, Heydecke G, Strub JR. Technical complications of implant-supported fixed partial dentures in partially edentulous cases after an
average observation period of 5 years. Clin. Oral Impl. Res. 18, 2007; 720–726
5 Schwarz MS. Mechanical complications of dental implants. Clin Oral Impl Res. 2000; 11 (Suppl.): 156–158
6 DIN 250-1: Bolted Connections with Reduced Shank; Survey, Range of Application and Examples of Installation. 1974–09
7 Köhler H, Jende S. Motorverschraubung. GWV Fachverlage GmbH, Lexikon Motorentechnik, Der Verbrennungsmotor von A bis Z; Wiesbaden 2004
8 ASTM F1295-05 Standard Specification for Wrought Titanium-6 Aluminum-7 Niobium Alloy for Surgical Implant Applications
9 ISO 5832 Wrought Titanium-6 Aluminum-7 Niobium Alloy; 1994-09-01
Résumé
Cet article donne une description détaillée de la
fonction de la liaison implant/abutment du système
d’implants Thommen. La liaison entre l’implant et
l’abutment est un des éléments les plus importants
d’un système d’implants. Différentes exigences sont
posées à la fonction, comme la hauteur minimale de
construction pour la flexibilité prothétique, des adap-
tations précises, une résistance à la fatigue opti-
male, etc. Le système d’implants Thommen utilise
une liaison intérieure associée à une bague de gui-
dage afin d’offrir la meilleure solution possible. La
liaison intérieure est formée d‘un hexagone assurant
la protection antirotationnelle et présente, par rap-
port à la liaison extérieure, un guidage plus long de
l‘abutment. Ce guidage est décisif pour la stabilité.
La bague de guidage est une particularité du
système d’implants Thommen: elle protège la vis
d’abutment des forces non axiales et empêche un
desserrage de la vis.
La bague de guidage réduit de plus la surface d’ap-
pui entre l’implant et l’abutment, ce qui offre une
pression superficielle plus élevée avec le
même couple de serrage et donc une meilleure
étanchéification contre les liquides corporels.
La tête de la vis d’abutment est petite, ce qui per-
met d’obtenir un canal de vissage plus fin,
nécessaire pour un soin esthétique optimal. Les
caractéristiques de fatigue optimales de la vis
d’abutment sont dues d’une part à la conception
d’une vis à tige allégée classique, telle qu’utilisée
dans la construction mécanique traditionnelle pour
des liaisons soumises à de fortes charges, et d’autre
part à l’utilisation d’un alliage titane à résistance
élevée.
Le système d’implants Thommen a été optimisé par
des calculs par éléments finis et la résistance à la fa-
tigue a été largement testée. Le système a été
conçu de sorte que la vis d’abutment agisse en tant
que point de rupture en cas de surcharge, par
exemple d’un accident, et protège ainsi l’implant
d’un dommage.
Riassunto
Nel presente articolo viene illustrata in dettaglio la
funzione della connessione impianto/abutment del
sistema Implantare Thommen. La connessione tra
l’impianto e l’abutment è uno degli elementi più im-
portanti di un sistema implantare. Vengono richiesti
diversi requisiti alla funzione, come un’altezza mini-
male per la flessibilità protesica, accoppiamenti pre-
cisi, resistenza ottimale alla fatica ecc.
Per offrire la migliore soluzione possibile nel sistema
Implantare Thommen viene impiegata una connes-
sione interna integrata da un anello di guida. La con-
nessione interna è dotata di un esagono con fun-
zione antirotazionale e, rispetto alla connessione
esterna, presenta una guida dell‘abutment più lunga.
Tale guida è determinante per la stabilità.
Una particolarità del sistema Implantare Thommen è
l’anello di guida: questo protegge la vite per
abutment dalle forze non assiali e impedisce un al-
lentamento della vite.
Inoltre l’anello di guida riduce la superficie di
appoggio tra impianto e abutment rendendo
possibile, a parità di coppia di serraggio, una pres-
sione superficiale più elevata e, di conseguenza, la
migliore tenuta possibile contro i liquidi corporei.
La vite per abutment presenta una testa di piccole
dimensioni, per ottenere un canale di avvitamento
più stretto. Ciò è necessario per una ricostruzione
ottimale dal punto di vista estetico. Le proprietà ide-
ali di resistenza alla fatica della vite per abutment si
devono da un lato al design di una classica vite con
gambo scaricato, del tipo tradizionalmente impie-
gato nella costruzione di macchine per connessioni
soggette ad un carico elevato dal punto di vista di-
namico, dall’altra all’impiego di una lega di titanio
estremamente resistente.
Il sistema Implantare Thommen è stato ottimizzato
grazie a calcoli FEM e la resistenza alla fatica è stata
ampiamente testata. Il sistema è stato progettato in
modo tale che, in caso di sovraccarico, come ad
esempio in caso di incidente, la vite per abutment
funge da punto di rottura prestabilita proteggendo
l’impianto da eventuali danni.
Resumen
En el presente artículo se describe de forma deta-
llada la función de la unión implante/pilar del sistema
de implantes Thommen. La unión entre el implante y
el pilar es uno de los elementos más importantes de
un sistema de implantes y debe satisfacer diferen-
tes requisitos, como una altura de construcción mí-
nima para permitir flexibilidad protésica, además de
unos ajustes precisos, una resistencia a la fatiga óp-
tima, etc.
Para poder ofrecer la mejor solución posible, en el
sistema de implantes Thommen se ha empleado
una unión interior complementada con un anillo
guía. Dicha unión está formada por un hexágono
para bloquear la rotación y, en comparación con la
unión exterior, presenta una guía del pilar más larga.
Esta guía es determinante para la estabilidad.
Una particularidad del sistema de implantes Thom-
men es el anillo guía: este elemento protege el torni-
llo de pilar de las fuerzas no axiales y evita que el tor-
nillo se afloje.
Además, mediante el anillo guía se reduce la superfi-
cie de apoyo entre el implante y el pilar, de modo
que con un mismo apriete se permite una mayor
presión superficial además del mejor sellado posible
frente a los fluidos corporales.
El tornillo de pilar tiene una cabeza pequeña que
permite utilizar un canal más fino. Esta característica
es necesaria para una reconstrucción estética óp-
tima. Las propiedades de fatiga óptimas del tornillo
de pilar se consiguen, por un lado, gracias al diseño
de un tornillo de dilatación clásico —como los em-
pleados en la construcción tradicional de maquinaria
para uniones dinámicamente sometidas a una ele-
vada carga—, y, por otro, mediante el uso de una
aleación de titanio extraordinariamente resistente.
El sistema de implantes Thommen ha sido optimi-
zado mediante cálculos por el método de elemen-
tos FEM y la resistencia a la fatiga ha sido amplia-
mente probada. En este sentido, el sistema ha sido
concebido de modo que, en caso de sobrecarga,
como sucede por ejemplo en un accidente, el torni-
llo del pilar actúe como punto de rotura nominal
para proteger el implante contra los daños.
SWISS PRECISION AND INNOVATION. SWISS PRECISION AND INNOVATION. www.thommenmedical.com
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