Stress breaker in rpd

Stress breaker in rpd

4. ED. AREA
TOOTH

7. VERTICAL LOAD
DERIVES SUPPORT FROM TWO
TISSUES WHICH ARE
COMPLETELY DIFFERENT

9. FACTORS INFLUENCING:
1.Magnitude , rate , previous history of force
2.Soft tissue displacebility
3. Abutment condition
4. Alveolar bone health

10. Kennedy’s class I with occlusalrests
placed distally on the distal abutment –
loaded vertically –distal displacement of
the abutment tooth
the arc of rotation of the saddle, which is in the
gingival area of the abutment tooth is almost
parallel to the mucosa ,resulting in minimal or no
support from the mucosa near the tooth

11. Occlusal rest placed mesially on the
abutment ,then the arc of movement of the
saddle becomes more perpendicular to the
mucosa , mesial fulcrum increases support
provided by the soft tissues

12. 1.Magnitude of vertical force
2.Physical characteristics of underlying
mucosa
3.Angulation of residual ridge to
horizontal
4.Periodontal condition of the abutment

13. Wrought alloys more flexible
than type IV gold more flexible
than cast alloys

14. 1.Inclined plane effect of cusps of posterior teeth
2.Steeper cusp inclines greater load
3.Flat ridge with marked fibrosis of the submucosa –
less resistance to lateral stress
Major factor
than vertical
component
1.Parafunction
2.Function
3.Adjacent
facial and
lingual
musculature
4.Type of clasp

15. Anteriorlythe buccalclasp arm minimizes
movement but posteriorlythe buccalridge
alone resists lateral displacement-less effective
than tooth
Rigid connection between the two saddles ,
rotational torque on the working side is
resisted on the balancing side by forward
pressure of the saddle against the distal
surface of its abutment

17. 1.Use of narrow posterior teeth
2.Shaping of flanges so they do not extend
beyond the zone of minimal conflict
3.Flanges kept thin to give a ‘streamlined’
appearance

20. 1.STRESS BREAKING
2.Combining rigid connection and a gingivally
approaching clasp
3.Combining rigid connection and an
occlusallyapproaching clasp
4.The disjunctdenture

30. HINGE , BALL AND
SOCKET, SLEEVE
OR CYLINDER
ATTACHMENTS
WROUGHT WIRE
CLASPS , SPLIT
MAJOR
CONNECTOR
FLEXIBLE BAR

32. SPLIT MAJOR CONNECTOR
FLEXIBLE BAR INTO THE
SADDLE AREA

33. RPI SYSTEM
ROACH CLASP

37. MALE / PATRIX
FEMALE / MATRIX
PARTS

38. ABUTMENT PLANNING
SADDLE DESIGN
RELATIONSHIP OF SADDLE TO
THE ABUTMENT

40. Michael and Gerardo (1987)

50. Developed by
Hans Dalla
Bona of Beil,
SW

53. ROTATIONAL -
DALBO
RESILIENT
SPRING LOADED
DALBO

54. Developed by Karl Clytens , a dental
laboratory technician from Belgium in
1951

56. THOMPSON
DOWEL-REST
SYSTEM
Removable partial
denture has a flexible
cast arm that engages
dimple on lingual
surface of crown and a
metallic block that seats
in the box