REVIEW OF LITERATURE

1916

1922

1923

1928

1930

1935

Prosthero described the cone theory as the basis of clasp

retention. He described the shape of crowns of molars and

premolars as that of two cones sharing a common base.

GE Everett described impression taking with fluid wax

compound. Later on, the following 4 types of fluid waxes were

introduced

1. Iowa wax (white) –Dr. Earl S Smith

2. Korrecta wax no.4 (yellow) –Dr. O.C. Applegate

3. H-L physiological paste (yellow) –Dr. C.S.Harkins

4. Adaptal wax (green) –Dr. Nathan G. Kaye.

Dr. smith developed IOWA wax and Korrecta wax at

university of IOWA and Korrecta.

Wax no. 4 was developed by Dr. O.C. Applegate and

Dr.S.G.Applegate at university of Michigan and Detroit

respectively.

Kennedy described the greatest bulge or diameter of the

crown as the height of contour. Cummer spoke of this line as

the guideline since it guided the placement of retentive and

non-retentive clasps

WE Cummer described impression (materials and

techniques) in partial denture service.

Roach designed a bar clasp which improved esthetics and

provided a greater flexibility of the retentive arm

De Van added the terms—suprabulge (surfaces sloping

superiorly) and infrabulge(surfaces sloping inferiorly)

1936

1936

1941

1942

1951

1952

1953

1956

1957

1959

1962

He designed embrasure saddle clasp as a means of providing retention where these is no edentulous space. It is used on dentulous side of the arch.

D.W.Mc Lean prosecuted his technique on making physiological impression of partially edentulous mouth. He also described fundamental principles of partial denture construction.

Stone showed experimentally that an adapted infrabulge clasp could deliver 143%more retention than a suprabulge clasp.

E.R.Granger described mechanical principles applied to partial denture construction.

Stress breakers were available in market in early 1940s. In 1942, Dr.E.Kennedy commented that stress breakers were the main cause of tooth loosening and partial denture failures. Their disadvantages overpower the advantages. He found them the main cause for the denture sore mouth.

Bletterfin claimed that the bar clasp is ineffective in reducing lateral forces falling on the abutment teeth.

G.W.Hindles modified original Mc Lean’s technique of making physiologic impressions of edentulous mouth. Holes were made in the trays in Hindle’s technique. He also described load distribution in extension saddle partial dentures.

W.L.McCraken compared tooth borne and tissue borne partial dentures in detail.

A.H.Schmidt expounded the principles of RPD construction.

G.W.Hindles described stress analysis in distal extension partial dentures

Warr claimed that a round wire could not be properly tapered and is therefore inadequate for retention

Kabcenell recommended placing the clasp in a passive position. He also believed that a precise path of insertion decreased the need for retention.

1963

1965

1966

1967

1970

1971

1973

1976

1978

1988

1988

1989

Kratochvil introduced the proximal plate and mesial occlusal rest modification of the bar clasp assembly.

J.B. Holmes described the influence of impression procedures and occlusal loading on partial denture movement.

R.J. Leupold made a comparative study of impression procedures for distal extension RPD. In the same year, Menetray recommended the use of the modified back action clasp or circumferential clasp for the most favorable force transmission to abutment teeth.

M.Herkneby did model experiments on the transmission of forces from a lower free end partial denture to the supporting teeth.

J.A. Raupuamo described single tray dual impression technique for distal extension partial dentures.

Cecconi, Asgar and Dootz stated that the factors of clasp assembly designs other than type of retentive clasp arm more significantly effect the magnitude of abutment tooth movement.

J.D. Walter described composite impression procedures for distal extension RPD. In the same year, Krol modified Kratochils concept and named it as RPI clasp system. He claimed that it was more esthetically acceptable and produced less stress on abutment tooth.

D.Henderson and T.E. Strewart described design and force distribution with removable partial dentures.

R.G. Craig and J.W. Farah described stresses from distal extension RPD

F. Vahidi described vertical displacement of distal extension ridges by different impression techniques.

H.G.E.L. Chaukawi , R.J. Goodkind, R.DeLong , and W.H.Dougloas described the effect of the resilient layer distal extension partial dentures on movement of abutments .

Aviv I, Ben U.Z and H.S. Cardash analyzed rotational movement of asymmetrical distal extension RPD.