Support in complete dentures /certified fixed orthodontic courses by Indian dental academy

SEMINAR ON,
SUPPORT
IN
COMPLETE DENTURES
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

 CONTENTS
 INTRODUCTION
 DEFINITION
 TYPES OF SUPPORT
 SNOWSHOE PRINCIPLE
 NATURE OF THE SUPPORTING TISSUE

 ANATOMIC CONSIDERATIONS OF DENTURE
BEARING AREA
 RELIEF REGIONS
 PRACTICAL CONSIDERATIONS
 SUMMARY AND CONCLUSION
 REFERENCES

INTRODUCTION
If the dentures and their supporting tissues are to
coexist for a reasonable length of time ,the dentist must
fully understand the anatomy of supporting and limiting
structures involved.
Incorporation of certain biological and physical factors
are necessary to ensure optimal complete denture
support.

 COMPLETE DENTURE SUPPORT IS,
 Resistance to vertical movement of the denture base
towards tissue.
 Counteracts forces towards ridges.
 Support – relationship between denture base & tissue
surface
 Maintain established - occlusal relation ,promote optimal
function, with minimal tissue ward movement & base
settling.

 DEFINITION
 GPT
 The foundation area on which the denture prosthesis
rest.
 BOUCHER
 The resistance to the vertical forces of mastication,
occlusal forces & other forces applied in a direction
towards the denture bearing area.

TYPES OF SUPPORT
 CONSIDERED IN 2 POINTS OF VIEW
 1.Dentures should confine to the underlying tissues so
that the occlusal forces can correctly oppose to one
another at initial closure & under functional loading.
 2.The denture should maintain this for a period of time
for the longevity of the dentures

SUPPORT IS ACHIEVED,
 INITIALLY
 By impression procedures that provide optimal extension
& functional loading of the supporting tissue which vary
in their resiliency.
 LONG TERM
 Directing the forces of occlusal loading towards those
tissue most resistant to remodeling & resorptive
changes.

FACTORS AFFECTING SUPPORT
1. Contour & quality of the residual ridge .
2. Extent of residual ridge coverage by denture base.
3. Type & accuracy of the impression registration .
4. Accuracy of the fit of the denture base .
5. Total occlusal load applied.

EFFECTIVE SUPPORT IS REALIZED WHEN,
 1.Denture extended cover maximum surface area
without impinging movable or friable tissue.
 2.Tissues capable of resisting resorption selectively
loaded during function.
 3.Tissue resist vertical displacement are allowed to
make firm contact with denture base during function.
 4.Compensation is made for varying tissue resiliency to
provide uniform denture base movement under function
& maintain harmonious occlusal relationship.

SNOWSHOE PRINCIPLE
 Of maximal extension is that
given a constant occlusal force,
broader denture bearing area decreases the
stress per unit area under the denture base,
decreases tissue displacement ,reduces
denture base movement.

NATURE OF THE SUPPORTING
TISSUES
1. SOFT TISSUE
2.HARD TISSUE
3.BONE FACTOR

SOFT TISSUES
 Supporting soft tissues must be capable of withstanding
the pressure induced through normal function of
prosthesis.
 Presence of keratinized, firmly bound mucosa permits
the tissue to better resist stress.

 Presence of layer of resilient submucosa permits
moderate compressibility without mechanical
impingement of mucosa between the denture base &
underlying bone
 The fatty & glandular mucosa acts as a hydraulic
cushion

 Regions which posses a thin or less keratinized mucosa
over bone without an intervening layer of
submucosa,should be relived or recorded without
displacement.
 This eliminates impingement of the soft tissue between
the denture base and bony foundation during occlusal
loading, thereby minimizing soft tissue trauma and
reducing pressure induced bony remodeling.

STRATEGY OF USING SOFT
TISSUE
 Mouth tissues should support the
denture rather than hold the denture by
suspension.

A denture may be supported ,
suspended, sustained by mucosal base in 3
ways;
 A denture is supported ; when the force is basewise &
perpendicular, resulting in compressive loads.
 A denture is suspended ; when the force is
counterbasewise, resulting in tensile loads.
 A denture is sustained ; when the force is basewise in
one area & counterbasewise in another area.

HARDTISSUES
 Requirement of ideal support is the presence of tissue
that are relatively resistant to remodeling and resorptive
changes.
 In case of over denture, preserving teeth retains not
only alveolar bone supporting teeth but also alveolar
bone adjacent to teeth.

 Minimizing the pressure in those areas most susceptible
to resorption, & directing the forces toward those region
relatively resistant to resorption can help to maintain a
healthy residual ridge.

BONE FACTOR
 It can be determined by studying the previous response
of patients bone to stress.
 Such stress may be in the form of extractions, surgical
trauma, forces generated by functioning prosthesis.

Bone responds to force by remodeling-
WOLF’S LAW
 The supporting alveolar bone may differ in its response
to stress as compared to basal residual ridge bone.
 Response of bone to stress is related to local anatomic
and physiologic variations within and between individuals
 Pressure tension concept:
pressure stimulates resorption ; tension maintains the
integrity or deposition

 Cortical bone more resistant to resorption
 Hence used in support of denture as recorded
relations are maintained over longer periods of
time.
 Muscle fiber attachments ensure tension on bone.
This minimizes resorptive changes.

ANATOMIC CONSIDERATION OF
DENTURE BEARING AREA
 AS EDWARDS & BOUCHER NOTED;
 “Since the success of the complete denture depends
largely on the relation of the dentures to anatomic
structures which support & limit them, familiarity with the
location & character of these structures is essential”.

MAXILLARY ANATOMIC CONSIDERATIONS
 Support for a maxillary denture - the
bone of two maxillae & palatine
bone.
 Palatine process of the maxillae &
palatine bone form foundation for
the hard palate, & support the
denture.
 They support the soft tissues that
increase surface area of basal seat.

HARDPALATE
 Covered by soft tissue of varying
thickness.
 Epithelium is keratinized
throughout.
 Submucosa is resilient but it is thin
in mid palatine suture.

 Tissue is displaceable.
 Contributes to the support of the
denture.
 Horizontal portion of the hard palate
lateral to the midline provides the
primary support area for denture.
 Area of rugae is set at an angle to the
ridge , it is the secondary stress
bearing area

ROOFLESS DENTURE
 Patients wearing roofless maxillary dentures are often
associated with alveolar ridge resorption.

 Tensor veli palati & levator palatine muscles of the soft
palate may provide the source of tension that
counteracts the pressure resorption normally expected
beneath the denture.

 All these properties dictates the essential
function of hard palate as the primary denture
support area.

RIDGE CREST
 Depends on nature of ridge &
bone factor of individual patient
.
 Broad square ,well developed
residual ridges covered by
firmly bound masticatory
mucosa & favorable intrinsic
bone factor provides good
support.

 The inclined facial surface of the
maxillary ridge provides little
support, although the peripheral
tissues should be contacted to
provide a border seal.
 Mucous membrane looses its
firm attachment to the
underlying bone as it extends
from the crest along the slopes
of the ridge.

 Secondary supporting area
area.
 Alveolar ridges undergo
remodeling changes when
subjected to functional stress
transmitted by tissue borne
prosthesis.

COMBINATION SYNDROME

MANDIBULARANATOMIC CONSIDERATIONS
 Support of lower denture- mandible
& soft tissue overlying it.
 Total support area of mandible is
less than maxillae.
 Denture bearing area
 Maxilla- 24 cm
 Mandible-14cm

PEAR SHAPED PAD
 Distal extent of keratinized
masticatory mucosa
 Formed by scaring of extracted 3rd
molar & its retromolar papilla.
 Denture short of this region
rapid resorption – settling of
denture base.

RETROMOLAR PAD
 Triangular soft pad of tissue at
distal end of lower ridge.
 Mucosa is composed of;
Thin,nonkeratinized epithelium
Loose alveolar tissue
 Submucosa-glandular tissue
fibers –buccinator superior,
constrictor temporalis
muscle,pterygomandibular
raphe

BUCCAL SHELF
 PRIMARY STRESS BEARING AREA.
 Cortical bone.
 Lies at rt angles to vertical occlusal
forces

 Total width of bony
foundation in this region
becomes greater with
more alveolar resorption.
Reason being width of
inferior border of
mandible is greater than
width of the alveolar
process.
.

 The buccinator muscle
fibers run antero
posteriorly permitting the
denture base to rest
directly on the muscle

MANDIBULARRESIDUAL CREST
 Depends on nature of ridge & bone
factor of individual patient .
 Broad square ,well developed
residual ridges covered by firmly
bound masticatory mucosa &
favorable intrinsic bone factor
provides good support.

Secondary support area, due to
Muscle attachment.
Cancellous bone
Less keratinized alveolar
mucosa
Lingual tissue over mylohyoid
ridge requires relief

 In markedly resorbed
mandibular ridge genial
tubercles resist resorption
 Provide a bony
foundation but cannot be
used as a primary stress
bearing area due to
friable overlying mucosa.

 In case of patients who have under gone vestibuloplasty
with split thickness skin grafts, have favourable
keratinized tissue over lying regions of muscle
attachments.
 In such cases genial tubercles can be considered as
primary support area.

RELIEF REGIONS
 Tissues that are susceptible to
resorption
 Regions with thin mucosa
 Region of mucosa overlying
neurovascular bundles

PRACTICAL CONSIDERATIONS
 Principle of impression making – maximal extension of
denture bearing area
 Mucostatic theory/Pressure free impression – based on
Pascal’s law
 But tissues vary in their ability to tolerate pressure and
transmit it according to their anatomic location and
histologic make up.

 Desirable impression technique – mild displacement of
more resilient tissues
 Tissues beneath the denture base be recorded in the
shape and contour that they assume on loading.
 Equalized pressure distribution minimizes localized
pressure concentration which otherwise would lead to:
Pressure induced resorption
Mucosal irritation
Base instability

REVIEWOF LITERATURE
 FRANK, conducted a study to determine the effect of
tray modifications & selection of impression materials on
pressures exerted on the denture supporting tissues .
 Conclusion:
 Difference in the pressure were coreleated to the use of
different impression materials.
 More pressures were measured at the crest of the ridge
than on the palate when no relief was used.
 Use of escape vents or relief was equally effective in
decreasing pressures & equalizing the pressures on the
ridge crest ,palatal area.

SUMMARY
 Dentist must base their technique on understanding the
biologic aspects of relationship between denture base &
supporting tissue.
 Anatomic regions providing primary support should make
positive contact with denture base under functional
loading .
 Areas unable to tolerate stress should be relived of
excessive contact with denture base.

CONCLUSION
 Impression techniques , materials & associated
procedures should be selected to effect the relationship
of the denture base to the underlying tissue that will
promote effective & physiologic support for complete
dentures.

REFERENCES
1.A.R.Tencate;Oral histology development structures
and function. 4th
edition.
2.Bouchers ; Prosthodontic treatment for edentulous
patients. 9th
& 11th
edition.
3.Claud.M.Fraleign –Improvement of tissues for the
support of complete dentures.JPD 1959;9;746.
4.Charles M Heartwell ; syllabus of complete
dentures.5th
edition.
5.Donald .E.Van. Scotter,- The nature of supporting
tissue for complete dentures. JPD 1965;15;285.
6.Frank.R.P-Analysis of pressure produced during
maxillary impression procedures.JPD 1969 22:400

7.M.M.Devan –Basic principles for impression making
JPD;1952;2;26.
8.T.E.JACOBSON.”A contemporary review of the
factors involved in complete denture part 111; support
; JPD 1983;49;306.

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