Dental implants cement retention vs screw retention

1. Dental Implants
Cement retention vs screw retention
John Beumer III DDS, MS
Robert Faulkner DDS, MS
Division of Advanced Prosthodontics, UCLA
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2. Cement
vs
screw
reten1on
Which
method
is
preferred
to
retain
implant
prostheses?
Both
methods
can
be
employed
if
used
properly.

3. Cement
retained
prostheses
Advantages
– Simplicity
– Familiarity
– Idealize
occlusal
contacts
• Occlusal
contacts
are
not
effected
by
the
screw
access
channel
– Esthe1cs
–
• Porcelain
occlusal
surfaces
can
be
developed
– Reduces
risk
of
porcelain
chipping
and
fractures
associated
with
the
screw
access
channel
Cement
retained
prosthesis
Screw
retained
prosthesis

4. Cement
retained
prostheses
Disadvantages
and
concerns
ª Requires
precise
margin
placement
ª Requires
a
me1culous
technique
ª The
volume
of
cement
used
must
be
carefully
controlled
ª
Cements
becomes
aOached
to
the
machined
surface
of
abutment
of
the
micro-­‐rough
surface
of
the
implant
difficult
to
remove
ª Prosthesis
is
not
easily
retrieved
ª Recurrent
loss
of
reten1on
when
reten1on
and
resistance
form
of
the
abutment
is
subop1mal
Residual
cement
may
be
impacted
subgingivally
secondary
to
incomplete
sea1ng
of
the
crown
or
extrusion
of
cement
subgingivally
predisposing
to:
ª Peri-­‐implant
mucosi1s
ª Peri-­‐implan11s

5. Major
Problem
Sub-­‐gingival
reten1on
of
cement
Two
issues:
ª Impac1on
of
cement
subgingivally
during
cementa1on
ª Incomplete
sea1ng
of
the
crown
These
two
phenomenon
predispose
to
peri-­‐implan**s
–
An
inflammatory
process
affec1ng
the
1ssues
around
an
osseointegrated
implant
in
func1on,
accompanied
by
bone
loss.
Courtesy
Dr.
C.
Goodacre

6. Major
Problem
Sub-­‐gingival
reten1on
of
cement
Two
issues:
ª Impac1on
of
cement
subgingivally
during
cementa1on
ª Incomplete
sea1ng
of
the
crown
It
may
take
several
years
before
the
excess
cement
becomes
apparent
(Thomas,
2009)
Courtesy
Dr.
C.
Goodacre

7. Major
Problem
–
Retained
cement
ª If
the
margin
is
sub-­‐gingival,
there
will
be
residual
cement
100%
of
the
1me
(Linkevicius
et
al,
2013).
ª Peri-­‐implan11s
may
ensue,
leading
to
loss
of
implants
and
o`en
the
adjacent
teeth
(Wilson,
2009;
Wadhani,
et
al,
2011).
ª 80%
of
cases
of
peri-­‐implan11s
are
secondary
to
sub-­‐gingival
cement
accumula1ons
(Wilson,
2009)
ª

8. Courtesy of Dr. C. Wadhwani
These
pa1ents
presented
with
peri-­‐implan11s
ª The
implants
are
s1ll
anchored
in
bone
but
their
prognosis
is
poor
ª Note
cement
adherent
to
the
surfaces
of
the
implants
ª The
methods
for
decontamina1on
of
the
implant
surfaces
and
gra`ing
these
site
have
been
problema1c
Major
Problem
–
Retained
cement
Courtesy of Dr. G. Perri

9. If
the
cement
margin
is
subgingival
it
is
not
possible
to
remove
all
the
cement
(Linkevicius
et
al,
2013)
Case
report
Prepable
abutment
An
impression
was
obtained
with
an
impression
coping
and
the
prepable
abutment
was
aOached
to
the
fixture
analogue
imbedded
in
the
master
cast.
Courtesy
Dr.
S.
Parvispour

10. Subgingival
cement
accumula1on
Prepable
abutment
ª The
abutment
was
prepared
so
that
the
margin
is
slightly
sub
gingival.
ª The
metal
ceramic
crown
was
completed
in
a
customary
fashion.
ª The
abutment
was
secured
to
the
implant
fixture
and
the
crown
is
then
cemented.
Courtesy
Dr.
S.
Parvispour
Case
report

11. Subgingival
cement
accumula1on
Prepable
abutment
v The
pa1ent
was
unhappy
with
the
esthe1c
result
and
so
a
hole
was
drilled
into
the
occlusal
surface
in
order
to
access
the
abutment
screw.
The
crown
and
abutment
was
then
removed
v Note
the
accumula1on
of
cement
subgingivally.
Courtesy
Dr.
S.
Parvispour
Case
report

12. Sub-­‐gingival
cement
accumula1on
Implant
Surface
Bone
Epithelium
Sulcus
Circumferen1al
collagen
fibers
ª Peri-­‐implant
1ssues
are
more
easily
displaced
from
the
surface
of
the
implant
because
of
the
absence
of
a
connec1ve
fibers
aOached
to
the
implant.
ª As
a
result
the
epithelial
aOachment
is
easily
severed
and
cement
can
be
impacted
to
the
level
of
the
bone
and
on
to
the
surface
of
the
implant.
Why
is
there
a
greater
risk
of
cement
accumula1on
in
the
sulcus
of
implant
crowns?

13. Challenges
of
cementa1on
ª Removal
of
cement
is
extremely
difficult,
especially
when
it
is
adherent
to
the
micro-­‐rough
surface
of
the
implant.
ª In
this
pa1ent
it
led
to
the
failure
of
the
implant
and
compromised
the
periodontal
support
for
the
adjacent
teeth
Courtesy
C.
Wadhani

14. Challenges
of
cementa1on
TPS
(titanium plasma spMachined
Machined c.p. Ti
Acid
etched
micro-­‐rough
implant
surface
Machined
surface
of
abutment
When
cement
becomes
adherent
to
either
the
surface
of
a
machined
or
milled
abutment
or
the
micro-­‐rough
surface
of
the
implant,
it
is
very
difficult
and
some1mes
impossible
remove.
Anodized
implant
surface

15. If
you
insist
upon
cementa1on
ª Control
the
volume
of
cement
ª Avoid
the
use
of
prefabricated
abutments
ª Use
customized
abutments
with
supra-­‐gingival
margins
in
the
posterior
quadrants,
especially
when
there
are
significant
undercuts
and
concavi1es
associated
with
the
abutment
ª Idealize
reten1on
and
resistance
form
ª Avoid
the
use
of
prefabricated
abutments
Cement
retained
prostheses

16. Preparing
custom
abutments
for
cementa1on
ª The
por1on
engaging
the
crown
should
not
be
polished.
It
can
be
roughened
or
prepared
with
grooves.
ª The
por1on
adjacent
to
the
gingival
1ssues
should
be
highly
polished

17. Types
of
cements
used
v Polycarboxylate
cements
should
not
be
used
because
they
contain
fluoride
which
will
corrode
the
1tanium
surface
of
the
implant
or
abutment.
v Resin
cements,
containing
hydroxylated
ethymethacrylate,
(HEMA)
which
is
potent
cytotoxic
agent,
should
be
avoided.
v Zinc
oxide
and
eugenol
cements
are
favored.
They
are
an1-­‐bacterial
and
are
radio-­‐opaque.
Courtesy
Dr.
C.
Goodacre

18. Types
of
cements
recommended
Zinc
oxide
and
eugenol
cements
are
favored
ª They
possess
an1bacterial
proper1es
ª They
are
radio-­‐opaque
(However,
excess
cement
on
the
buccal
and
labial
surfaces
may
not
be
seen)
Courtesy
Dr.
C.
Goodacre

19. Cementa1on
Recommenda1ons
Use
a
provisional
cement
(ZOE)
such
as
temp-­‐bond
unless
the
reten1on
is
compromised
by
a
short
abutment,
a
very
tapered
abutment,
or
the
screw
access
hole
eliminates
reten1ve
surface(s)

20. Cementa1on
Recommenda1ons
When
reten1on
is
compromised
by
implant
angula1on
and
the
posi1on
of
the
abutment
screw
orifice,
use
zinc
phosphate
cement
Courtesy
of
Dr.
C.
Goodacre

21. Cementa1on
Recommenda1ons
This
implant
crown
loosened
a`er
2
months
when
cemented
with
ZOE.
Courtesy
of
Dr.
C.
Goodacre

22. Poor
reten1on
and
resistance
form
secondary
to
excessive
labial
inclina1on
When
reten1on
is
compromised
by
the
angula1on
of
the
abutment
screw
channel,
another
op1on
is
to
retain
the
crown
with
a
lingual
cross
pinning
screw.

23. Problem
-­‐
Insufficient
interocclusal
space
to
design
an
abutment
with
appropriate
resistance
and
reten1on
form.
ª Recurrent
loss
of
reten1on
is
seen
most
o`en
when
lack
of
interocclusal
space
prevents
development
of
custom
abutments
with
sufficient
axial
wall
lengths
to
retain
the
crown.
ª Another
advantage
with
screw
reten1on
-­‐
the
emergence
profile
of
the
crown
is
idealized
Courtesy
G.
Perri
Screw
reten1on
favored
when
there
is
Lack
of
interocclusal
space

24. This
custom
abutment
has
an
excessive
taper.
Cementa1on
Recommenda1ons
Custom
abutments
must
be
designed
with
appropriate
reten1on
and
resistance
form

25. The
addi1on
of
grooves
will
improve
resistance
form
and
is
recommended
for
single
tooth
molar
restora1ons.
Cementa1on
Recommenda1ons
Custom
abutments
must
be
designed
with
appropriate
reten1on
and
resistance
form

26. Cementa1on
procedures
Carefully
control
the
volume
of
cement
used
(Wadhwani
and
Pineyro
(2009)
ª The
intaglio
surfaces
of
the
crown/s
is
lined
with
teflon
tape
ª The
implant
restora1on
is
seated
firmly
onto
the
abutments
and
then
removed
ª A
fast
seing
vinyl
polysiloxane
material
is
injected
into
the
intaglio
surfaces
of
the
crown/s.
ª The
excess
material
is
used
as
a
handle.
When
the
material
has
polymerized,
it
is
removed
from
the
crown/s.

27. Carefully
control
the
volume
of
cement
used
(Wadhwani
and
Pineyro
(2009)
ª The
teflon
tape
is
removed
from
the
crown/s
ª A
suitable
cement
is
prepared
and
a
thin
layer
is
placed
inside
the
crown/s
ª The
VPS
abutment
analogues
are
seated
into
posi1on
and
the
excess
cement
is
removed.
ª A
very
thin
layer
is
added
and
the
crown
is
seated
into
posi1on
ª Excess
cement
is
removed
with
curved
plas1c
instruments.
Cementa1on
procedures

28. Challenges
of
cementa1on
Plakorm
reduc1on
(plakorm
switching)
ª If
the
cement
becomes
impacted
below
the
margin,
its
removal
is
problema1c
ª Access
is
extremely
difficult
if
not
impossible
without
laying
a
so`
1ssue
flap
Courtesy
Dr.
G.
Perri

29. Challenges
of
cementa1on
ª How
will
you
remove
the
cement
if
it
becomes
impacted
beneath
the
margins
of
this
implant
crown?
ª More
than
likely,
you
will
not,
given
the
severity
of
the
undercut
associated
with
the
custom
abutment.
ª Therefore,
under
these
circumstances
it
is
advisable
to
place
the
margins
supra-­‐gingival.

30. Cement
retained
prostheses
Posterior
quadrants
It
is
advisable
that
margins
of
custom
abutments
be
designed
to
be
slightly
supra-­‐
gingival
in
order
to
facilitate
removal
the
cement

31. Cement
retained
prostheses
• Ven1ng
is
not
effec1ve
Ven1ng
makes
it
easier
to
seat
the
crowns,
especially
a
mul1-­‐unit
implant
born
prosthesis,
but
does
not
prevent
impac1on
of
cement
sub-­‐gingivally.

32. Cement
retained
prostheses
Packing
retrac1on
cord
is
ineffec1ve
in
preven1ng
subgingival
cement
accumula1ons
ª There
is
risk
of
detaching
the
epithelial
aOachment
when
packing
the
cord
ª Sub-­‐gingival
cement
accumula1on
is
not
prevented
by
packing
gingival
retrac1on
cord
prior
to
cementa1on
ª Cement
has
been
shown
to
extrude
apical
to
the
retrac1on
cord
(Wadhwani
et
al,
2011).

33. Avoid
the
use
of
preformed
non-­‐prepable
abutments
Issues
of
concern
v Posi1on
of
the
cement
margin
in
rela1on
to
the
gingival
margin
v Par1cularly
significant
in
the
anterior
region
v Impac1on
of
cement
into
the
gingival
sulcus
is
highly
likely
v Difficulty
in
sea1ng
the
crown
because
of
hydraulic
pressure

34. Preformed
abutments
are
problema1c
v The
margin
between
the
crown
and
the
abutment
does
not
follow
the
gingival
margin.
v There
is
significant
risk
of
trapping
cement
beneath
the
gingival
1ssues
upon
cementa1on
in
the
proximal
areas.
Courtesy
Dr.
A.
Pozzi

35. Preformed
nonprepable
abutments
ª This implant crown was retained by a prefabricated abutment.
ª Note the inflammation associated with the peri-implant gingiva
2 1/2 years post insertion.
ª Radiograph revealed significant bone loss.
Dx
–
Peri-­‐implan11s

36. Preformed
nonpreparable
abutments
This
pa1ent
presented
with
peri-­‐implant
mucosi1s
3
years
post
inser1on
of
the
crown.
The initial x-ray
appeared to
indicate that the
crown was seated.
A subsequent x-ray,
taken at right angles
to the long axis of the
implant, revealed that
the crown, was not
seated.
• Inability to completely seat the crown onto the abutment is a
common complication associated with preformed abutments.
• Lingual access holes may help relieve the hydraulic pressure
and enable seating of the crown but it will not be possible to
remove all the cement that extrudes subgingivally

37. Apical
migra1on
of
bone
and
peri-­‐implant
so`
1ssues
in
the
esthe1c
zone
Causes
of
apical
migra1on
of
bone
and
so`
1ssues
• Thin
layer
of
labial
bone
overlying
the
implant
upon
implant
placement
(less
than
1
mm)
• Poor
surgical
technique
• Peri-­‐implan11s
• Natural
progression
Even
when
implants
are
placed
properly
and
in
ideal
posi1on
and
with
proper
angula1on,
there
is
risk
of
apical
migra1on
long
term,
even
in
a
pa1ent
with
good
oral
hygiene

38. Apical
migra1on
of
bone
and
peri-­‐implant
1ssues
• Thin
labial
bone
• Labial
inclina1on
• Poor
surgical
technique
• Peri-­‐implan11s
Even
when
implants
are
placed
properly
and
in
ideal
posi1on
and
with
proper
angula1on,
there
is
risk
of
apical
migra1on
long
term,
even
in
a
pa1ent
with
good
oral
hygiene
This
a
concern
in
the
esthe1c
zone

39. Avoiding
subgingival
cement
accumula1on
in
the
esthe1c
zone
Implant
crowns
with
supra-­‐gingival
margins
– Fabricate
the
custom
abutment/s
with
a
ceramo-­‐metal
– Bake
porcelain
onto
the
custom
abutment
with
margin
placed
supra-­‐gingivally

40. Cement
the
crown
to
an
abutment
outside
the
mouth
and
retain
it
with
the
abutment
screw
• In
the
esthe1c
zone
this
technique
requires
that
the
abutment
screw
exit
in
the
cingulum
area.

41. ª Retrievability
ª Avoid
trapping
cement
subgingivally
ª Less
risk
of
peri-­‐implan11s
ª Carry
restora1on
more
subgingivally
ª For
more
ideal
emergence
profile
and
contour.
ª
Advantageous
in
the
esthe1c
zone
ª More
predictable
sea1ng
a
bridge
with
a
pon1c
ª Predictable
reten1on
par1cularly
when
a
cemented
restora1on
would
have
a
very
short
axial
wall
because
of
limited
inter-­‐occlusal
or
restora1ve
space.
Arguments
in
favor
Screw
reten1on

42. In
the
esthe1c
zone
screw
reten1on
is
preferred
Advantages
ª Retrievability
ª Less
risk
of
peri-­‐implan11s
ª Extend
the
porcelain
margins
deeper
subgingivally
ª Apical
migra1on
will
not
compromise
the
esthe1cs
of
the
prosthesis

43. UCLA
abutment
technique
The
restora1on
is
connected
directly
to
the
implant
plakorm

44. UCLA
abutment
technique
Advantages
ª Retrievability
ª Less
risk
of
peri-­‐implan11s
ª Extend
the
porcelain
margins
deeper
subgingivally
ª Accounts
for
apical
migra1on
of
bone
and
peri-­‐implant
so`
1ssues

45. Custom
substructures
and
abutments
with
reten1on
provided
by
cross
linking
screws
Advantages
ª Retrievability
ª Less
risk
of
peri-­‐implan11s
ª Extend
the
porcelain
margins
deeper
subgingivally
ª Accounts
for
apical
migra1on
of
bone
and
peri-­‐implant
so`
1ssues
Screw
reten1on

46. Custom
substructures
and
abutments
with
reten1on
provided
by
cross
linking
screws
Advantages
ª Retrievability
ª Less
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