Influence of survey line on designing of clasp / implant dentistry course/ implant dentistry course

Influence of survey line on
designing of clasp
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

Influence of survey line on designing of
clasp
1. Circumferential clasp
Contour analysis
(F.C Elliott.)
Parts of typical
circumferential clasp
Passive placement of flexible third of clasp
arm at undercut zone
2. Bar clasp (F.E Roach clasp )

• Attainment of lateral force
transmission
Placement of three
components of clasp arm

Horizontal
reciprocation
Clasp body and arm failed to
encircle tooth more than 180
Minimum encirclement and
additional encirclement for
effective for horizontal
reciprocation.
Vertical
reciprocation
The different vertical levels of clasp
arms may result in tooth tipping
The same vertical levels of
clasp arms eliminates the
possibility of tooth tippingwww.indiandentalacademy.com

• In a typical tooth the neutral zone or survey line
lies in the middle of the near zone of the tooth
surface , and the junction of the middle and
gingival thirds in the far zone.
Division & Nomenclature
of tooth surfaces.
Typical and atypical types of survey lines
Blatterfein’s classification

• In first atypical variation
which may be called
Type A the survey line is
in the occlusal third of the
tooth at the beginning of
the near zone, rapidly
approaches the gingival
margin at the junction of
the far and the near
zones, and is on gingival
margin in the greater part
of the far zone on the
tooth surface.

• In the second
variation, which may
be called Type B the
survey line is in
occlusal third of both
the near and the far
zones.

• In the third variation,
which may be called
Type C the survey
line is at the gingival
margin in both the
near and far zones.

Atypical Type A survey line
This is the survey line
that is too high in the
near zone and too
low in the far zone as
compared to the
typical survey line.
• For its attachment to
main part of the
partial denture, three
directions of
attachments are
available:

1. Near direction
resulting in a reverse
loop clasp arm.
2. Far direction
resulting in a reverse
attachment clasp
arm
3. Gingival direction
resulting in a bar
clasp arm.

Atypical Type B survey line
• This is the survey line
which is too high in
the near and far zone
as compared to
typical survey line.
• Two factors control
clasp design with
such a survey line.:
– Esthetics and
– Periodontium of the
abutment tooth

1. If esthetic is unimportant
and periodontium is
good the typical
circumferential clasp arm
may be designed at a
high level.
2. If esthetics is important
and the periodontium is
good semirigid and
flexible thirds of a
typical; circumferential
clasp arm may be
eliminated on the buccal
or labial surface www.indiandentalacademy.com

• If the periodontium is
weak, ideal contour
must be established on
the abutment tooth by
operative procedure, to
permit typical clasp
design at the lowest
possible vertical level.

Atypical Type C survey line
• This is the survey line that is
at the gingival margin in both
he near and far zones.
• For such a survey line the
undercuts on
– The distobuccogingival
and distolinguogingival
corners of adjacent teeth.
– The far proximal surface
and
– The near proximal surface,
may be used to effect
primary retentionwww.indiandentalacademy.com

• If the distobuccogingival
and distolinguogingival
corners of adjacent
teeth is used the typical
circumferential clasp is
extended from the
abutment to the
undercut corner of the
adjacent tooth resulting
in an extension clasp
arm.

1. Flexible segment placed in
undercut on far proximal
surface.
2. Near direction of attachment
effected by use a buccal arm.
Rigid third on lingual surface
for lateral force transmission
and reciprocation.
3. Near direction of attachment
effected by use a lingual arm
Rigid third on buccal surface
for lateral force transmission
and reciprocation.
Clasp design for an atypical type C survey line using a
single flexible segment on the far proximal surfaces and
a near direction of attachment

Effecting retention on an atypical type C survey line by
use of far proximal surface undercut.
undercut on far proximal
surface undercut.
2. Flexible segment attached
from near direction
3. Flexible segment attached
from gingival direction

single flexible segment on far proximal surface and a
gingival direction of attachment.
1. Flexible segment placed
in undercut on far
proximal surface.
2. Gingival direction of
attachment effected by
use a buccal strut bar
3. Rigid thirds are added
both buccally and
lingually to effect lateral
force transmission.

single flexible segment on far proximal surface and a
in undercut on far
proximal surface.
use a lingual strut bar
both buccally and
force transmission

Clasp design for an atypical type C survey line using two
flexible segment on far proximal surface and a near
direction of attachment.
1. Flexible segment
placed in undercut
on far proximal
surface.
2. Near direction of
attachment effected
by use of a buccal
and a lingual arm

flexible segment on far proximal surface and a gingival
in undercut on far
proximal surface.
use of a buccal and
lingual strut bar
both buccally and
force transmission

Effecting retention on an atypical Type C survey
line by the use of a near proximal surface
undercut.
1. Flexible segment is
placed in the near
proximal surface
undercut
2. Flexible segment
attached from a far
direction
3. Flexible segment
attached from a
gingival directionwww.indiandentalacademy.com

single flexible segment on near proximal surface and a
far direction of attachment.
1. Flexible segment
placed in undercut on
near proximal surface.
2. Far direction of
attachment effected
by use a lingual arm
3. Far direction of
attachment effected
by use a buccal arm

undercut on near proximal
surface.
attachment effected by use
a buccal strut bar
3. Rigid thirds are added both
buccally and lingually to
effect lateral force
transmission

undercut on near proximal
surface.
attachment effected by use
a lingual strut bar
3. Rigid thirds are added both
buccally and lingually to
effect lateral force
transmission

flexible segment on near proximal surface and a far
1. Flexible segment
placed in undercut
on near proximal
surface.
2. Far direction of
attachment effected
by use a buccal and
a lingual arm

flexible segment on near proximal surface and a
in undercut on near
proximal surface.
use a buccal and a
lingual strut bar.
both buccally and
force transmission

Conclusion
1. To properly design the clasp component of
removable partial denture prosthesis, an
understanding of basic function of clasp is
essential.
2. Primary retention is effected by the flexible third
of clasp arm . It may contact the tooth surface in
either of the ways, to accomplish resistance to
vertical dislodgement:
a) Active spring tension against a parallel sided or
undercut tooth surface (active spring tension brings
with it the problems of clasp equilibrium.)
b) Passive placement against an undercut tooth surface

1. Circumferential clasp 2. Bar clasp (F.E Roach clasp )
Contour analysis (F.C Elliott.)
Parts of typical circumferential clasp
Passive placement of flexible third of
clasp arm at undercut zone

3. a) Lateral force transmission to abutment teeth is
effected by the placement of rigid third of the clasp arm
against a non-undercut tooth surface.
b) Supplementary measures for multiple clasping, fixed
splints and stress breaker are necessary if the
supporting structures of the tooth surface are
unfavorable.
c) Effectively to counteract forces resulting from these
functional contacts and there by avoid tooth movement
clasp arm must encompass more than 180o
of tooth
circumferences (horizontal reciprocation) and will be
placed on equal vertical level as close to gingiva as
possible ( vertical reciprocation)www.indiandentalacademy.com

• Attainment of lateral
force transmission
Placement of three
components of clasp arm
Horizontal Reciprocation Vertical Reciprocation

4. Atypical clasping procedures will be
followed when the ideal clasp design are
not feasible because of unfavorable tooth
contour or tooth position embodying the
basic function of primary retention and
lateral force transmission.
5. Atypical clasp are dictated by three
characteristic atypical survey lines –
Atypical A, B, C.
6. Atypical survey line the surface (buccal or
lingual ) is divided into the Near zone (near
to edentulous area and the Far zone (half
away from edentulous area)

Division & Nomenclature
of tooth surfaces.
Typical and atypical types of survey lines
Blatterfein’s classification

1. If esthetic is unimportant
and periodontium is
good the typical
circumferential clasp arm
may be designed at a
high level.
2. If esthetics is important
and the periodontium is
good semirigid and
flexible thirds of a
typical; circumferential
clasp arm may be
eliminated on the buccal
or labial surface

3. If the periodontium is
weak, ideal contour
must be established on
the abutment tooth by
operative procedure, to
permit typical clasp
design at the lowest
possible vertical level.

Thank you
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Influence of survey line on designing of clasp / implant dentistry course/ implant dentistry course

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