This document discusses factors affecting denture retention, including classification, interfacial forces, adhesion, cohesion, oral and facial musculature, atmospheric pressure, undercuts, parallel walls, and gravity. It defines retention as the resistance of a denture to forces that attempt to displace it from its basal seat. Primary retention comes from physical and mechanical means like surface area, adaptation, viscosity and secondary retention from surrounding musculature. Denture adhesives are discussed as a way to augment existing retention mechanisms by increasing adhesion, cohesion and viscosity between the denture and mucosa.

3.  Introduction
 Definition
 Factors affecting retention
- Classification
- Interfacial force
- Adhesion
-Cohesion
-Oral & facial musculature

4. -Atmospheric Pressure
-Undercuts, Rotational insertion paths,
Parallel walls
-Gravity
 Denture Adhesives
 Conclusion
 Bibliography

5.  Success of treatment with CD
 Integration of oral functions +
psychological acceptance
 Perception of the dentures as stationary
during function

6.  ‘That quality inherent in the prosthesis
which resists the force of gravity,
adhesiveness of foods, and the forces
associated with the opening of jaws’
- GPT
 The resistance of removal in a direction
opposite that of insertion
- Boucher

7.  The resistance of the movement of a
denture from its basal seat, especially in
a vertical direction
- Winkler
 The resistance it poses to withdrawal
from its planned position in the mouth
-Grant & Johnson

8.  Atmospheric pressure
 Surface tension
 Viscosity of saliva
 Physical retention:
area of the denture
adaptation of denture
viscosity of saliva
volume of saliva
wettability of the denture base resin

9. RETENTION
ANATOMICAL
Size of the denture
bearing area
Quality of the denture
bearing area
Parallel ridge walls
PHYSIOLOGICAL
Saliva
PHYSICAL
Adhesion
Cohesion
Interfacial surface
tension
Capillarity
Atmospheric pressure
Gravity
MECHANICAL
Undercuts
Retentive springs
Magnetic forces
Denture adhesives
Suction chambers & discs
Palatal implants
MUSCULAR
Oral musculature
Facial musculature

10.  Primary retention
-physical means
-mechanical means
 Secondary retention
- surrounding musculature
- shape of the denture borders &
flanges
- psychological factors
- proper instructions

11.  Mastication
 Adhesive food
 Gravity (upper)
 Surrounding musculature
 Occlusal prematurities
 Parafunctional habits

12.  ‘The tension or resistance to separation
possessed by the film of liquid between
two well-adapted surfaces’
- GPT
 ‘The resistance to separation of two
parallel surfaces that is imparted by a
film of liquid between them’

13.  Interfacial surface tension
 Viscous tension

14. INTERFACIAL SURFACE TENSION
 Thin layer of fluid that is present between
two parallel planes of rigid material
 Ability of the fluid to wet the rigid
surrounding material
 Low surface tension : maximize contact-
spread out in thin film
 High surface tension : minimize its
contact – formation of beads on the
material’s surface

15.  Processed denture base materials-
higher wettability
 High surface tension reduced on coating
by the salivary pellicle
› Retention by virtue of the tendency of the
fluid to maximize the contact between the
denture base & mucosa

16. Capillarity
‘That quality or state, because of surface
tension causes elevation or depression of
the surface of a liquid that is in contact
with a solid’
- GPT

17.  Close adaptation between denture
base & mucosa- thin film of saliva in the
space
› Retention- Capillary tube in which the liquid
seeks to increase its contact

18.  Important in maxilla
 If two plates with interposed fluid
immersed in the same fluid- no resistance
 External borders of mandibular denture
awash in saliva

19. INTERFACIAL VISCOUS TENSION
 Force holding two parallel plates
together that is due to viscosity of the
interposed liquid

20.  Stefan’s law: For two parallel, circular
plates of radius (r)
that are separated by a newtonian
(incompressible) liquid of viscosity (k), &
thickness (h),
the force (F) necessary to pull the plates
apart at a velocity(V)
in a direction perpendicular to the
radius will be
F=(3/2)πkr4 V
h3

21.  Viscous force viscosity of the fluid
 Viscous force thickness of the medium
 Viscous force opposing surface area

22.  Optimal adaptation- minimal ‘h’
 Maximizing denture bearing area-
maximum ‘r’
 Increasing the viscosity of the medium
 Slow steady displacing action-small ‘V’
effective at removing the denture than a
large ‘V’
 Enhanced by ionic forces- adhesion &
cohesion

23.  ‘Physical attraction of unlike molecules
for each other’
IONIC FORCES
Salivary glycoproteins
Acrylic resin
in denture
base
Surface
epithelium of the
mucous
membrane

24.  Xerostomia :Adhesion between denture
base & the dry mucosa
 Not very effective- mucosal abrasions &
lacerations
 Ethanol free rinse with aloe or lanolin
 Saliva substitute with
carboxymethylcellulose/ mammalian
mucin
 Sjogren’s syndrome: 5-10mg oral
pilocarpine tds

25.  Retention by adhesion with area
covered by denture
 Mandibular dentures , small jaws, very
flat alveolar ridges- less adhesion
 Dentures extended to limits of the health
& function of oral tissues
 Preserve the alveolar height

26.  ‘Physical attraction of like molecules for
each other’
 Within the layer of interposed saliva &
maintains its integrity
 Normal saliva not very cohesive unless
modified
 High mucinous saliva- though more
cohesive, less retentive

27.  Supplement retention if:
 Teeth are positioned in the neutral zone
 Polished surfaces of the denture are
properly shaped
 Buccal & lingual flanges should be so
shaped that the musculature fits
automatically

28. Buccal flange
 Buccinators tend to retain both
 Tongue perfect the border seal if: lingual
surfaces of the lingual flanges slope
toward the centre of the mouth
MAXILLA:
Slope up & out
from the occlusal
plane
MANDIBLE:
Slope down & out
from the occlusal
plane

29.  Lingual side of the distal end of the
lingual flange:
 Guides the base of the tongue on top of
the lingual flange
 Ensures the border seal at the back end
of mandibular denture
 Base of tongue: emergency retentive
force

30.  Most effective in retention when:
 The denture bases are properly
extended to cover the maximum area
possible
 The occlusal plane is at the correct level
 The arch form of the teeth is in the
neutral zone

31.  Resist dislodging forces to dentures with
an effective seal
 Called Suction: resistance to removal
from the basal seat
 No suction unless another force is
applied
 Suction alone applied: serious damage
to the health of the soft tissues

32.  Force exerted perpendicular to & away
from the basal seat of a properly
extended & fully seated denture
 Pressure between the tissues & the
denture drops below the atmospheric
pressure: resists displacement
 Retention area covered by the
denture

33.  Most effective in retention when:
 Denture has a perfect seal around its
entire border
 Proper border molding with
physiological, selective pressure
techniques is carried out

34.  Modest undercuts enhance retention:
resiliency of the mucosa & submucosa
 Exaggerated bony undercuts:
compromise retention
 Less severe ones: extremely helpful
 Lateral tuberosities
 Maxillary premolar areas
 Distolingual areas
 Lingual mandibular midbody areas

35.  Undercuts necessitate adopting a
rotational path of insertion: resists vertical
displacement
 Inferior to the retromolar pad: posterior
end placed first, from the superior &
posterior before rotating the anterior
segment down

36.  Anterior alveolus: anterior part inserted
in a posterior & superior direction &
posterior border rotated over the
tuberosities
 More important when other retentive
mechanisms are weak:
 Loss of normal anatomical contours
 Surgically created undercuts

37.  Prominent alveolar ridges with parallel
buccal & lingual walls increase
the surface area maximize
interfacial & atmospheric forces
 Limit the range of displacive force
directions
 Flat ridges resist displacing forces
perpendicular to the basal seat, but
susceptible to movement parallel to it

38.  Retentive force for the mandibular &
displacive for the maxillary- when the
person is upright
 Weight of the prosthesis- gravitational
force insignificant
 Heavy maxillary prosthesis unseat if the
other retentive forces – suboptimal

39.  Increasing the weight of the mandibular
denture- beneficial when other retentive
factors are marginal
 Xerostomia patients prefer heavier
maxillary prostheses

40.  Commercially available
nontoxic, soluble material that is applied
to the tissue surface of the denture to
enhance retention, stability&
performance
 Products which enhance the treatment
outcome
 US: 33% of denture wearers use adhesive
products
 Sale exceeded 200 million$ in 2001

41. Dentists should:
 Educate all denture wearing patients
about the advantages, disadvantages&
uses of adhesives
 Identify those patients for whom such a
product is advisable and/or necessary
for a satisfactory denture wearing
experience

42. STRICTLY INADVISABLE FORMS OF
ADHESIVES
 Home reliner/repair kits
 Paper/cloth pads
 Self applied cushions
 Thin wafers of water soluble material:
adherent to denture & basal tissue- don’t
flow

43. Possible sequelae:
 Soft tissue damage
 Alterations in occlusal relations & VD
 Exacerbation alveolar bone destruction

44.  Augment the already operating
retentive mechanisms
 Enhance retention through optimizing
interfacial forces by:
1. Increasing the adhesive & cohesive
properties & viscosity of the interposed
medium
2. Eliminating the voids between the
denture base & its basal seat

45.  Hydrated material formed by adhesives-
stick readily to the tissue surface & the
mucosal surface of the denture
 More cohesive than saliva- resists
displacing pull
 Increases viscosity of saliva
 Hydrated material swells up in the
presence of saliva/water: obliterates
voids

46.  Before early 1960’s: VEGETABLE GUMS
 Karaya
 Tragacanth
 Xanthan
 Acacia
 Modest nonionic adhesion to denture &
mucosa

47. Drawbacks
 Very little cohesive strength
 Highly water soluble(particularly in hot):
washed out readily
 Allergic reactions- Karaya & methyl
paraben(preservative)
 Acetic acid odor
 Short-lived & unsatisfactory adhesive
performance

48.  Presently : SYNTHETIC MATERIALS
 Mixtures of the salts of short acting
Carboxymethylcellulose (CMC)
long acting (polyvinyl methyl ether
maleate)
‘gantrez’ polymers

49.  CMC hydrates & displays quick-onset
ionic adherence to both dentures&
mucous epithelium
 Original fluid increases its viscosity &
CMC increases in volume- eliminates
voids between prosthesis & basal seat
 Enhance the interfacial forces acting on
the denture

50.  Polyvinylpyrrolidone (‘povidone’)
behaves like CMC
 Gantrez salts: More protracted time
course than necessary for the onset of
hydration than CMC,
hydrate & increase adherence &
viscosity

51.  Display molecular cross-linking more
pronounced & longer lived in Calcium-
Zinc gantrez than in Calcium- Sodium
gantrez
 All polymers fully solubilised & washed
out by saliva : hastened by the presence
of hot liquid

52. OTHER COMPONENTS:
 Petrolatum, Mineral oil, Polyethylene
oxide : bind the materials & make
placement easier
 Silicone oxide, Calcium stearate:
powders to minimize clumping
 Menthol, Peppermint oils: flavoring
 Red dye: Coloring
 Sodium borate, Methylparaben,
Polyparaben: Preservatives

53.  No reports of tissue reactions excepting
uncommon allergic reactons to karaya/
methyl paraben
 Earlier formulations had benzene-
carcinogen
 Lessened inflammation of the underlying
tissues if dental hygiene is maintained

54.  Incisal bite force in well fitting dentures
over well- keratinized ridges with
favorable anatomical features
 Can be improved for well fitting dentures
over inferior basal tissues

55.  Frequency of dislodgement - chewing
 Increased confidence & security in
chewing- but no improvement in
chewing performance
 Improvement in chewing efficiency
during adjustment to new dentures

56. OBJECTIONS:
 Grainy/ gritty texture of the powder
 Taste or sensation of semidissolved
adhesive material that escapes from the
posterior & other peripheries
 Difficulties in removing adhesives from
the oral tissues & denture
 The cost of the material

57.  Well made complete dentures do not
satisfy a patient’s perceived retention &
stability expectations
 Candidates for implant supported
prosthesis , precluded by health,
financial or other restraints

58.  Salivary dysfunction
 Xerostomia- medications, irradiation,
systemic disease, disease of salivary
glands
 Need to be educated- deliberately
moisten the adhesive bearing denture

59.  Neurological disorders
 CVA- oral cavity insensitive to tactile
stimulation/ paralysis of oral musculature
 Help to accommodate to new dentures
 Dentures fabricated before stroke

60.  Orofacial Dyskinesia/ Tardive Dyskinesia
 Exaggerated, uncontrollable muscular
actions of tongue, lips, cheeks &
mandible
 Side effect of:
- phenothiazines
- neuroleptics
- GI medications
-Dopamine blocking drugs

61.  Resective surgical/ traumatic
modifications of the oral cavity
 Oral neoplasia
 Loss of integrity of intraoral structures
 Even in the presence of surgically
created rotational undercuts

62.  Poorly fitting or improperly fabricated
prosthesis
 Hypersensitivity to any of the
components

63.  Major information source to the patient-
dentist
 Effects of powder formulations do not last
long compared to cream formulations
 Initial ‘hold’ is better for them compared to
creams
 Easier to clean out
 The least amount of the material that is
effective should be used:
0.5-1g/denture unit

64. POWDERS:
 Clean prosthesis moistened- thin even
coat of adhesive sprayed onto the tissue
surface of the denture
 Excess is shaken off & it is firmly seated
 Sprayed denture slightly moistened with
water before insertion- inadequate
salivation

65. CREAMS
2 approaches
1. Placement of thin beads of adhesive in
the depth of the dried denture in the
incisor & molar regions
 Anteroposterior bead in the midpalate-
maxillary

66. 2. Small spots of cream placed at 5mm
intervals throughout the fitting surface of
the dried denture- even distribution
 Denture then seated & inserted firmly
 Requires moistening before placement in
cases of xerostomia

68.  Daily removal of the adhesive- soaking
prosthesis in water / soaking solution
overnight
 If not possible, running hot water over
the tissue surface & scrubbing with a
suitable hard bristle brush

69.  Adhesive adherent to alveolar ridges &
palate – rinsing with warm/ hot water-
firmly wiping the area with
gauze/washcloth saturated with hot
water
 Discomfort will not be resolved by
placing a ‘cushioning layer’ of adhesive
under the denture

70.  Professional management required:
 Pain /soreness
 Gradual increase in the quantity of
adhesive required
 Patients recalled annually for mucosal
evaluation& prosthesis assessment

71.  Frequently regarded as unesthetic,
impedes dentist’s ability to appraise the
health of oral tissues & the true
adaptation
 Use of denture adhesive & residual ridge
resorption- believed to be correlated:
no scientific basis
 Reduce the amount of lateral
movements that denture undergoes
while in contact with basal tissues

72.  Patient may ignore the need for
professional help when dentures actually
become ill fitting
 Integral part of a professional service &
their adjunctive benefits must be
recognised

73.  Irrespective of the underlying reasons for
the patient’s dissatisfaction with the
prosthesis, dentist must realize that a
patient’s judgement of the treatment
outcome is what defines prosthodontic
success
 Though complete denture retention is a
complex phenomenon, it is every patient’s
invariable need that the prosthesis stays firm
& stable during function & hence every
possible attempt should be made by the
dentist to achieve it

74.  Prosthodontic Treatment for Edentulous
Patients- Zarb & Bolender,Twelfth edition
 Essentials of CompleteDenture
Prosthodontics- Sheldon Winkler,Second
edition
 Textbook of Prosthodontics- Deepak
Nallaswamy
 Complete Denture Prosthodontics- John
Joy Manappallil