Stability in complete /certified fixed orthodontic courses by Indian dental academy

STABILITY IN COMPLETE
DENTURE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


INTRODUCTION


Definition
The quality of a denture to be firm, steady
or constant to resist displacement by
functional stresses and not to be subject to
change of position when forces are
applied. GPT


VARIOUS FACTORS AFFECTING
STABILITY
1. TISSUE SURFACE
 Anatomy of residual ridge
 Height
 Contour
 Arch form
 Palatal vault
 Quality of soft tissue covering the ridge
 Quality of the impression
 Adaptation of denture base to tissue
2. POLISHED SURFACE
3. OCLUSAL SURFACE
 Tooth position
 Occlusal plane
 Ridge relation

1. Tissue Surface
Vertical Height Of Residual Ridge
The height of the residual ridge influences the
stability of complete denture:
Increased height = Increased stability


CONTOUR OF RESIDUAL RIDGE


ARCH FORM
Square or tapered arches tend to resist
rotation of the prosthesis better than
ovoid arches


PALATAL VAULT
Steep palatal vault may enhance stability
by providing greater surface area of contact


Quality of Soft tissue covering the
Ridge
 The crest of the upper ridge is covered with
fibrous connective tissue which usually
closely attached to the bone.


TYPES

PRELIMINARY
IMPRESSION

FINAL
IMPRESSION

1.Hard with thin mucosal
lining

Modeling compound

Medium fusing compound

2. Average amount of
connective tissue with
average tissue resilency

Modeling compound

Zinc oxide and eugenol
paste

3. Heavy pad of
mucoperiostium not firmly
attached to underlying
bone

Freely flowing irreversible
hydrocolloid

Freely flowing zinc oxide
eugenol paste

4. Hyper plastic tissue
Extremely displaceable

Soft free flowing alginate
material

Freely flowing alginate or
thin mix of POP.


Author: Buckley

Quality of Impression
1. Should be as accurate as possible.
2. Surface should be smooth and duplicate all the
details accurately.
3. Should be devoid of voids and any rough
surfaces.
4. Should not wrap on removal.
5. Should be dimensionally stable and the cast
should be poured as soon as possible.


ADAPTATION OF DENTURE BASE TO
TISSUE SURFACE
FRIEDMAN
Contacting of the labial and buccal flanges with the
labial and buccal ridge slope serve as critical factors
in contributing for the stability”

BOUCHER
Stability requires “maximum use of all bony foundation where
the tissue are firmly and closely attached to the bone’’


Mandibular Lingual Flange


2. POLISHED SURFACE

The action of certain muscle group must be
permitted to occur with out interference so that
they will not dislodge the prosthesis during the
function
 The external surface should be developed to
hormonize with the associated functioning of
tongue,
lips and cheek.

2. Polished surface


IMPORTANCE OF THE MODIOLUS AND
ASSOCIATED MUSCULATURE
 The Modiolus is an
anatomic landmark near
the corner of the mouth
that is formed by the
intersection of several
muscles of the cheeks
and lips. These include
the
orbicularis
oris,
buccinator,
caninus,
tgriangularis,
and
zygomaticus muscles.
Fish..

Modiolus
 The denture base must be contoured to permit the modiolus
to function freely. In the premolar region the mandibular
denture should exhibit both a shortened and narrowed
flange to permit the action that draws the vestibule
superiorly and the modiolus medially against the dentures.

Buccinator
 The buccinator muscle may be divided into superior, middle
and inferior divisions. According to FISH,”The superior fibers
act seat the maxillary denture, the middle fibers controls the
bolus of food, and the inferior fibers contribute to mandibular
denture stability.


CONTOUR OF POLISHED SURFACE
 The polished surfaces of the denture influence
the fit.
1. Contour of the bulk of the denture must be in
such way that it does not interfere with the
normal function of the tongue, cheeks, and lips
2. There is less gingival prominenece on the
buccal and labial surfaces of the lower dental
arch than on the upper dental arch.
3. The lingual-gingival prominence
on the
mandible arch is minimal

4. The contours of the denture should be
harmony with the surrounding contacting
tissues.
5. The lingual surface of the denture must not
interface with the normal movements of the
tongue.


3.Occlusal Surface
Tooth position
During both functional and para functional
movements, the occlusal surface should not
strike prematurely in localized areas

Anterior and posterior teeth should be
arranged as close as possible to the position
once occupied by the natural teeth with only
slight modifications made to improve leverages
and esthetics.

Occulsal surface
A mandibular plane that is too high to can
result in reduced stability.
 lateral tilling force are magnified as the
plane is raised.
 an elvated occlusal plane prevents the
tongue from reaching over the food table
into the buccal vestibule.

Ridge relation
 Normal dental relationships of the artificial
teeth set on ridges that are in severe
posterior cross bite can adversely affect
stability.


Theories of occlusion
Balanced occlusion
“The simultaneous contacting of the maxillary and mandibular
teeth on the right and left and in the posterior and anterior
occlusal areas in centric and eccentric positions, developed
to lessen or limit tipping or rotating of the denture bases in
relation to the supporting structures”. GPT

Lingualized Occlusion
Provide both limited range of excursive balance and
directing of forces to the lingual side of the lower ridge
during working-side contacts. Such concepts may minimize
horizontal stress and enhance denture stability.

Lingualized Occlusion
Provide both limited range of excursive balance and
directing of forces to the lingual side of the lower ridge
during working-side contacts. Such concepts may
minimize horizontal stress and enhance denture stability.

Zero-degree teeth
Zero-degree teeth may reduced horizontal forces there

by minimizing the unseating of the denture.

CONCLUSION


References
J.Pros.Den-80 (5); 150-161, 1955
J.Pros.Den-21 (4); 359-363, 1969
J.Pros.Den-49 (2); 165-172, 1983
J.Pros.Den-92 (6); 509-518, 2004


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Stability in complete /certified fixed orthodontic courses by Indian dental academy

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