Support in Complete Denture

SUPPORT IN COMPLETE
DENTURE
FACTORS AFFECTING SUPPORT IN COMPLETE
DENTURE
• Contour & quality of the residual ridge
• Extent of residual ridge coverage by denture base
• Type & accuracy of the impression registration
• Accuracy of the fit of the denture base
• Total occlusal load applied

EFFECTIVE SUPPORT IS REALISED WHEN,
• The denture is extended to cover a maximal surface area without

impinging on movable or friable tissues,
• Those tissues most capable of resisting resorption are selectively loaded

during function,
• Those tissues most capable of resisting vertical displacement are allowed

to make firm contact with the denture base during function, and
• Compensation is made for the varying tissue resiliency to provide for

uniform denture base movement under function and maintain a
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
TYPES OF SUPPORT
CONSIDERED IN 2 POINTS OF VIEW:
• Dentures should confine to the underlying tissues so that the occlusal

forces can correctly oppose to one another at initial closure & under
functional loading.
• 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
PRACTICAL CONSEDERATION FOR SUPPORT
• 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
NATURE OF THE SUPPORTING TISSUES :
• SOFT TISSUE
• HARD TISSUE
• BONE FACTOR
SOFT TISSUE
• 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 CONSEDERATIONS
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
HARD PALATE
• 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 DENTURES
• 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
MANDIBULAR ANATOMIC 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.

RETRO MOLAR 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
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
MANDIBULAR RESIDUAL 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

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SUPPORT IN COMPLETE

• Extent of residual ridge coverage by denture base

• Type & accuracy of the impression registration

• Accuracy of the fit of the denture base

• Total occlusal load applied

• The denture is extended to cover a maximal surface area without

• Those tissues most capable of resisting resorption are selectively loaded

• Those tissues most capable of resisting vertical displacement are allowed

• Compensation is made for the varying tissue resiliency to provide for

• Of maximal extension is that given a

CONSIDERED IN 2 POINTS OF VIEW:

• Dentures should confine to the underlying tissues so that the occlusal

• By impression procedures that provide optimal extension & functional

• Principle of impression making – maximal extension of denture bearing

• Mucostatic theory/Pressure free impression – based on Pascal’s law

• But tissues vary in their ability to tolerate pressure and transmit it

• Equalized pressure distribution minimizes localized pressure concentration

• Presence of layer of resilient submucosa permits moderate compressibility without

• The fatty & glandular mucosa acts as a hydraulic cushion

• A denture may be supported , suspended, sustained by mucosal

• A denture is supported ; when the force is basewise &

• A denture is suspended ; when the force is counterbasewise,

• A denture is sustained ; when the force is basewise in one area &

• Requirement of ideal support is the presence of tissue that are relatively

• Minimizing the pressure in those areas most susceptible to resorption, &

• It can be determined by studying the previous response of patients bone

• Such stress may be in the form of extractions, surgical trauma, forces

Bone responds to force by remodeling-

• Response of bone to stress is related to local anatomic and physiologic

• Cortical bone more resistant to resorption

• Hence used in support of denture as recorded relations are maintained

• Muscle fiber attachments ensure tension on bone. This minimizes

• Covered by soft tissue of varying thickness.

• Patients wearing roofless maxillary dentures are often associated

• All these properties dictates the essential function of hard palate as

• Depends on nature of ridge & bone factor of individual patient .

• Broad square ,well developed residual ridges covered by firmly bound

• Mucous membrane looses its firm attachment to the underlying bone as it

• Secondary supporting area area.

• Alveolar ridges undergo remodeling changes when subjected to functional

• Support of lower denture- mandible & soft tissue overlying it.

• Total support area of mandible is less than maxillae.

• Denture bearing area

• 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.

• Triangular soft pad of tissue at distal end of lower ridge.

• Mucosa is composed of; Thin,nonkeratinized epithelium Loose alveolar

• Submucosa-glandular tissue fibers –buccinator superior, constrictor

PRIMARY STRESS BEARING AREA.

• Lies at rt angles to vertical occlusal forces

• The buccinator muscle fibers run antero posteriorly permitting the

• Depends on nature of ridge & bone factor of individual patient .

• Broad square ,well developed residual ridges covered by firmly bound

• Secondary support area, due to Muscle attachment.

• Cancellous bone Less keratinized alveolar mucosa Lingual tissue over

• In markedly resorbed mandibular ridge genial tubercles resist resorption

• In case of patients who have under gone vestibuloplasty with split