RRR

1. residual RIDGE RESORPTION
Della s indran
iind MDS

2. CONTENTS
• INTRODUCTION
• DEFINITIONS
• BASIC CONCEPT OF BONE
• MECHANISM OF BONE
RESORPTION
• CLASSIFICATION OF RRR
• ETIOLOGY OF RRR
• PATHOLOGY OF RRR
• PATHOPHYSIOLOGY OF RRR
• PATHOGENESIS OF RRR
• CHANGES IN MAXILLA AND
MANDIBLE
• EPIDEMIOLOGY OF RRR
• DIAGNOSTIC AIDS TO
DETECT RRR
• CONSEQUENCES OF RRR
• PROSTAGLANDINS AS
MEDIATORS OF RRR
• CALCIUM HOMEOSTASIS
AND RRR
• OSTEOPOROSIS AND RRR
• MANAGEMENT OF RRR
• REVIEW OF LITERATURE
• CONCLUSION
• REFERENCES

3. INTRODUCTION
• Residual ridge resorption (RRR) is a major disease that
results in functional impairment of stomatognathic
system.
• Treatment of edentulous patients requires
maintenance of this phase that must be carried out
throughout the patient’s lifetime.

4. DEFINITIONS
• Residual bone – “That component of maxillary or
mandibular bone, once used to support the roots of
the teeth, that remains after the teeth are lost.”
• Residual ridge – “The portion of the residual bone
and its soft tissue covering that remains after the
removal of teeth.”
• Residual ridge crest – “The most coronal portion of
the residual ridge.”
• RESIDUAL RIDGE RESORPTION – “A term used for
the diminishing quantity and quality of the residual
ridge after teeth are removed - GPT 9

5. BASIC CONCEPT OF BONE
• The structural elements of bone are:
• Osteocytes found in bone lacunae.
• The intercellular substance or bone matrix consisting of fibrils
and calcified cementing substance.
• Osteoblasts.
• Osteoclasts
• Osteoprogenitor cells

6. INTERCELLULAR SUBSTANCE
ORGANIC PART – 33% - 35%
• Collagen – 88% - 90%
• Non-collagen – 10% - 11%.
• Mono-, Di-, Poly- and Oligosaccharides – 6% -9%
• Proteoglycans – 0.8% (sulphated and non-sulphated)
• Sialoproteins, Glycoproteins – 0.35%
• Lipids – 0.4%

7. INORGANIC PART – 65% - 67%
• Calcium & Phosphates – 95%
• Hydroxyapatite Crystals – Ca10(PO4)6OH2
• Magnesium
• Trace elements – Nickel, Iron, Fluoride, Cadmium,
Magnesium, Zinc and Molybdenum.

8. TYPES OF BONE
According to bone density:
• Compact bone
• Trabecular bone
 Microscopically:
• Woven bone
• Lamellar bone
• Bundle bone
• Composite bone

9. MECHANISM OF BONE RESORPTION
Attachment of osteoclasts to mineralised surface of bone
Creation of a ruffled border and an acidic environment through
action of the
proton pump
Dissolution of the Hydroxyapatite
Fall in pH to 2.5-3 in the osteoclast
resorption space

10. The organic components of the intercellular substance are
removed by proteolytic action of the osteoclasts.
The Ca salts (inorganic) are dissolved by a chelating action of
the osteoclasts.
• As resorption takes place, the osteocytes released may revert
to osteoblasts or become osteoclasts, depending on the
physiologic and pathologic demands.
• Histologically, bone apposition and resorption take place in
close approximation, making it possible to balance the shape
and size of bone.

13. CLASSIFICATION OF RRR
• According to Branemark et al in 1985, ridges were
classified on the basis of bone quantity and quality by
radiographic means.
BONE QUANTITY : (Branemark)
• Class A : Most of the alveolar bone is present
• Class B : Moderate residual ridge resorption occurs
• Class C : Advanced residual ridge resorption occurs
• Class D : Moderate resorption of the basal bone
• Class E : Extreme resorption of the basal bone

14. BONE QUALITY :
• Class 1 : Almost the entire jaw is composed of
homogenous compact bone.
• Class 2 : A thick layer of compact bone surrounds a
core of dense trabecular bone.
• Class 3 : A thin layer of cortical bone surrounds a core
of dense trabecular bone.
• Class 4 : A thin layer of cortical bone surrounds a core
of low-density trabecular bone.

15. BY WICAL AND SWOOPE :
• Class I : Up to one third of the original
vertical height lost.
• Class II : From one third to two thirds of
the vertical height lost.
• Class III : Two third or more of the
mandibular height lost.

16. NIEL’S CLASSIFICATION :
• Class 1 : Approximately 0.5 inch of space exists between
mylohyoid ridge and floor of mouth.
• Class 2 : Less than 0.5 inch of space exists between mylohyoid
ridge and floor of mouth.
• Class 3 : The mylohyoid muscle is at the same level as the
mylohyoid ridge.

17. ATWOOD’S CLASSIFICATION :
• Order 1 : Pre-extraction
• Order 2 : Post-extraction
• Order 3 : High, well rounded
• Order 4 : Knife-edge
• Order 5 : Low, well round
• Order 6 : Depressed

18. ATWOOD’S CLASSIFICATION
• ORDER I : PRE EXTRACTION : The tooth held in
its socket with very thin labial and lingual
cortical plates.
• ORDER II : POST EXTRACTION : The healing
period includes clot formation, clot
organisation, filling of the socket to the height
of the cortical plates with new trabecular
bone, & epithelialisation over the socket site.
The edge of the RR are still sharp.

19. • ORDER III : HIGH , WELL –ROUNDED RESIDUAL
RIDGE :The cortical plates are rounded off ,
narrowing of the crest of the ridge has begun, &
remodeling of the internal trabecular structure
has taken place.
• ORDER IV : KNIFE-EDGE RESIDUAL RIDGE -
There is marked narrowing of the labiolingual
diameter of the crest of the ridge with a
compensatory internal remodeling which
sometimes leads to incredibly sharp crest of the
ridge.

20. • ORDER V : LOW WELL-ROUNDED - The end
results of progressive labiolingual narrowing
of a knife-edge ridge is the disappearance of
the knife-edge portion. A more widely
rounded, but considerably lower RR remains
• ORDER VI : DEPRESSED RR - Resorption has
continued below the level of the genial
tubercle.

21. SIEBERT’S CLASSIFICATION
• Class I: Buccolingual loss of tissue with
normal ridge height in apicocoronal
dimension
• Class II: Apicocoronal loss of tissue with
normal ridge width in a Buccolingual
dimension
• Class III: Combination Bucco - lingual and
apico-coronal loss of tissue resulting in
loss of normal height and width

22. MERCIER’S CLASSIFICATION :
• Group 1 : No atrophy
• Group 2 : Minimal atrophy
• Group 3 : Moderate atrophy
• Group 4 : Severe atrophy
• Group 5 : Extremely severe atrophy
ZELSTER’S CLASSIFICATION :
• Group 1 : High muscle attachment & minimal RRR.
• Group 2 : Severe residual ridge resorption with pain.
• Group 3 : Absence of residual ridge.
• Group 4 : Severe resorption of basal bone.
Mercier, P., & Lafontant, R. (1979). Residual alveolar ridge atrophy: Classification and influence of facial morphology. The
Journal of Prosthetic Dentistry, 41(1),

23. American college of prosthodontists :
Based on Bone Height (Mandible only)
• Type I : Residual bone height of 21 mm or greater .
• Type II : Residual bone height of 16 - 20 mm.
• Type III : Residual alveolar bone height of 11 - 15 mm.
• Type IV : Residual vertical bone height of 10 mm.
McGarry TJ, Nimmo A, Skiba JF, Ahlstrom RH, Smith CR, Koumjian JH. Classification system for complete edentulism. Journal
of Prosthodontics. 1999 Mar;8(1):27-39.

24. MISCH’S CLASSIFICATION
• D1 -Dense cortical bone.
• D2 -Thick dense to porous cortical bone on crest and
cortical trabecular bone within.
• D3 - Thin porous cortical bone on crest and fine
trabecular bone within
• D4 - Fine trabecular bone

25. ETIOLOGY OF RRR
It is postulated that RRR is a multifactorial,
biomechanical disease that results from a combination
of the following factors:
• Anatomic
• Mechanical
• Metabolic
• Functional
• Prosthetic

26. ANATOMIC FACTORS
It is postulated that RRR varies with the quantity and quality of the
bone of the residual ridges:
• RRR α anatomic factors
Size of ridge
Type of bone removed
Amount of bone
Quality of bone

27. • Quantity of bone : It is not a good prognostic factor for
the rate of RRR, because it has been seen that some large
ridges resorb rapidly and some knife edge ridges may
remain with little changes for long periods of time.
• Quality of bone: On theoretic grounds, the denser the
bone, the slower the rate of resorption because there is
more bone to be resorbed per unit time.

28. MECHANICAL FACTORS
• RRR α FORCE
DAMPING EFFECT
Amount Duration
Frequency
Direction &
Distribution
Force

29. • Damping effect takes place in the mucoperiosteum, which has a
viscoelastic property
• Maxillary bone (RR) is frequently broader, flatter and more
cancellous than its mandibular counterpart. So it is ideally
constructed for the absorption and dissipation of energy.
• Frost pointed out that the trabaculae in cancellous bone are
arranged parallel to direction of compression deformation.

30. METABOLIC FACTORS
• Generally, body metabolism is the net sum of all the
building up (anabolism) and the tearing down (catabolism)
going on it the body.
• RRR α bone resorption factors
bone formation factors

31. • The thyroid hormone affects the rate of metabolism of
cells in general and hence the activity of both, the
osteoblasts and osteoclasts.
• Parathyroid hormone influences the excretion of
phosphorous in the kidney and also directly influences
osteoclasts.
• Vit C aids in bone matrix formation.
• Vit D acts through its influence on the rate of absorption
of calcium in the intestines
• Various members of Vit B complex are necessary for bone
cell metabolism.

32. • According to Reifenstein, in the young person, there is
a relative predominance of anabolic hormones
(estrogen and testosterone) over the anti anabolic
hormones( cortisone and hydrocortisone) resulting in
continued growth of skeleton.
• He further states that, as people get older, the
anabolic hormones are so reduced that the anti-
anabolic hormones are in relative excess with the
result that bone resorption may take place faster than
bone formation and that bone mass may be reduced.
Reifenstein, E. C., Jr.: The Relationship of Steroid Hormones to the Development and Management of
Osteoporosis in Aging People, Clin. Orthop. 10:206-253, 1957.

33. BONE RESORPTION FACTORS
Local
Endotoxins from
dental plaque
Osteoclast activating
factor
Prostaglandins
Heparin
Trauma
Systemic
Circulating hormones
Osteoporosis
Hypophosphataemia
Parathormone
Calcitonin

34. PROSTAGLANDINS – MEDIATORS OF RRR
• Prostaglandins (PG) has been demonstrated to
mediate bone resorption. PG is not stored in cells in
their final form but is quickly released in response to
mechanical, physiologic and pathologic stimuli.
• It is hypothesised that osteoblasts are involved in
bone resorption by coupling with osteoclasts, because
the cellular receptor against various bone resorbing
hormones (including PG) have been found in
osteoblasts but not in osteoclasts.

35. • PG’s are released from many kinds of cells including
inflammatory cells such as neutrophilic granulocytes
and macrophages as well as local mesenchymal cells
such as osteoblasts and cells of the periodontal
ligament.
• Mechanical stimulation of osteoblastic cells causes a
significant elevation in cAMP and PG synthesis.

36. CALCIUM HOMEOSTASIS AND RRR
• The only sources of Ca for the body are
Diet
Bone reservoir.
• Ca homeostasis is maintained by controlling Ca obtained
from these 2 sources. This can occur by altering internal
absorption mechanisms (income) or tubular reabsorption
(recycling) or by liberation of Ca from the skeleton via
resorption (savings).
• There is a reciprocal relationship between Ca
concentration and bone resorption to maintain Ca
homeostasis.
• As the level of serum calcium drops, resorption is

37. • Skeletal depletion of calcium occurs as a result of stimulation of
parathyroid gland and the alveolar bone is the first to be
affected. This is due to the function of parathyroid hormone in
maintaining the blood calcium level by mobilizing it from bones
by osteoclastic activity.
• Simultaneously , there is an increased renal excretion of
phosphate, which disturbs the blood calcium:phosphorous ratio
by raising the blood calcium level. This results in mobilization of
phosphates from bones by osteoclastic activity.
• Under these conditions , alveolar bone becomes susceptible to
diseases like osteoporosis.

39. OSTEOPOROSIS AND RRR
Osteoporosis is characterized by low bone mass and micro
architectural deterioration of the bone, which leads to
increased bone fragility and risk of fracture.
• It has two forms.
The more prevalent Type I (post menopausal) affects
women for a decade or so after menopause.
The Type II (senile or idiopathic) attacks males and
females at any age for no obvious reason.
• RRR maybe a manifestation of Type I osteoporosis .
• Both cortical and trabecular bone are affected.

40. Treatment for osteoporosis
• Estrogen replacement therapy
• Ca supplement
• Good nutrition and regular exercise
• New drugs for systemic osteoporosis are
under evaluation, including
biophosphonates to inhibit osteoclasts
• Calcitonin to reduce resorption.

41. FUNCTIONAL FACTORS
• Forces within the physiological limits are beneficial in their
massaging effect. On the other hand, increased or
sustained pressure produces bone resorption.
• Bone that is used as by regular physical activity will tend to
strengthen within certain limits , while bone that is in
disuse will tend to atrophy.
• Disuse atrophy - It is directly proportional to the extent of
disuse.
• After the loss of natural teeth, bone cannot be stimulated
by a denture base as the teeth did internally. The lack of
internal stimuli contributes to the disuse atrophy.

42. PROSTHETIC FACTORS
Long continued use of ill fitting dentures:
Loss of bone
Incorrect occlusion
Incorrect jaw relation
Under-extended dentures: Lead to less retentive dentures
and increased load per unit area. Common sites are:
Lingual flange
Buccal shelf area
Retromylohyoid area and Retromolar pad

43. Excessive stress resulting from artificial environment:
• Human tissues have not evolved in nature to accept
ranges of artificial things and the denture acts as an
artificial entity.
• Abuse of tissues from lack of rest:
• Bone is moldable. It can tolerate masticatory forces
within the limits of physiologic tolerance but
exceeding that it causes damaging forces which will
result in resorption of the alveolar bone and alteration
in tissue form .

44. Faulty improper impression procedures :
• Before impression procedures, care has to be taken on
selection of trays. If the tray selected is too large, it
will distort the tissues around the borders of the
impression. If it is too small, the border tissues will
collapse inward onto the residual ridge. This will
reduce the support by the denture flange.
• The use of minimal and selective pressure impression
techniques should be implicated in order to avoid
distortion of the mucosa and ridge area which may be
under considerable pressure.

45. Error in relating maxilla to the cranial landmarks
(orientation relation):
• The plane of the maxilla should be oriented to the
facial reference line (Camper’s plane or ala tragus
line). If not, may cause instability of denture leading to
resorption.
Lack of freeway space due to increased vertical
dimension of occlusion:
• Freeway space is present in the teeth in the
physiologic rest position. At times, due to lack of
freeway space the bone resorbs because of increased
vertical height in an attempt to create the space.

46. Incorrect Centric relation record:
If the Centric relation is not recorded properly, the
mandibular teeth will not occlude properly with those on
the maxillary arch. This proper occlusion is essential to the
health of bony support. Otherwise, it causes pressure on
bone due to failure of denture stability. Hence resorption of
base occurs
Faults in selection and placement of posterior teeth
When the ridge is weak, resorbed and covered by only
lining mucosa, then the use of the posterior teeth should be
smaller. This will limit the occlusal surface, which in turn will
minimise the forces directed to such a ridge.

47. Overclosure
• The loss of proper vertical dimension after the insertion of
complete dentures results in the triggering of a cyclic
series of events detrimental to the health of the residual
alveolar ridge.
• Overclosure causes the mandible to be moved or rotated
in an upward and forward direction causing occlusal
disharmony and excessive trauma to anterior region .

48. PATHOLOGY OF RRR
Gross pathology:
• The basic structural change in RRR is a reduction in the
size of the bony ridge under the mucoperiosteum. It is
primarily a localised loss of bone structure.
• In some situations, this loss of bone may leave the
overlying mucoperiosteum excessive and redundant.
• Gross reduction of the bone in size and shape that occurs
on the external surface on the labial, crestal and lingual
aspects of the residual ridge.
• Bones with the most severe RRR may display the gross
porosity of medullary bone on the crest of the ridge

49. • RRR does not stop with the residual ridge, but may well go
below where the apices of the teeth were, sometimes leaving
only a thin cortical plate on the inferior border of the mandible
or virtually no maxillary alveolar process on the upper jaw.
• Sometimes a knife edge ridge maybe masked by a redundant or
inflamed soft tissue, which can be detected by palpation or by
Lateral cephalometric radiographs.

50. Microscopic pathology:
• Studies have revealed evidence of osteoclastic activity
on the external surface of the crest of the residual
ridges. The scalloped margins of Howship’s Lacunae
sometimes contain visible osteoclasts .
• Studies have shown total absence of periosteal
lamellar bone on the crest of the residual ridge, and a
presence of cortical layer consisting of an endosteal
type of bone, or no cortical layer but simply a
medullary type of trabecular bone.
• Varying degrees of inflammatory cells, including
lymphocytes and plasma cells, have also been seen.

51. PATHOPHYSIOLOGY
Osteoblasts
Bone formation
Increased in
growth
Osteoclasts
Bone resorption
Increased in
Osteoprosis,
periodontal diseases
Bone Remodelling

53. • RRR is a localised pathologic loss of bone that is not built
back by simply removing the causative factors.
• Yet, the physiologic process of internal bone remodeling
goes on even in the presence of this pathologic external
osteoclastic activity that is responsible for the loss of so
much of bone substance.
• Even if a great deal of RR is removed in total, there is
often a cortical layer of bone over the crest of the ridge.
This means that new bone has been laid down inside the
RR in advance of the external osteoclastic removal of
bone.
• The mechanism of the reduction of the mandibular
residual ridge actually represents a modified version of the
Enlow’s “V” principle, showing external resorption
accompanied by endosteal deposition.

55. PATHOGENESIS OF RRR
• RRR is a chronic progressive irreversible disease which
proceeds slowly over a long period of time from one stage
to next
• Autonomous regrowth has not been reported.
• Tallgren, Atwood & Coy studied rate of residual ridge
resorption for 25 years
• Mean ratio of anterior maxillary RRR to anterior
mandibular RRR was 1:4
• RRR is more in mandible than in maxilla and reverse can
also occur.

57. • WHY THERE IS MORE RESORPTION SEEN IN MANDIBLE THAN
MAXILLA ?
1. Mandible provides a smaller surface area of support for the
dentures
2. Amount of cancellous bone is lesser as compared to maxilla
• Dentures help to preserve the horizontal dimensions of residual
ridge to some extent & vertical dimensions undergo resorption
especially in mandible (4 times)

58. CHANGES IN the MAXILLA AND the
MANDIBLE

59. CHANGES IN MAXILLA
• Maxillary teeth are generally directed downward and
outward, so bone reduction generally is upward and
inward. Since the outer cortical plate is thinner than the
inner cortical plate, resorption from the outer cortex tends
to be greater and more rapid. As the maxilla becomes
smaller in all dimensions, the denture bearing area (basal
seat) decreases.
• The bone of the maxillae resorb primarily from the
occlusal surface and from the buccal and labial surfaces.
• Thus the maxillary residual ridge loses height and maxillary
arch becomes narrower from side to side and shorter
anteroposteriorly.

61. CHANGES IN MANDIBLE
• The anterior mandibular teeth generally incline upward and
forward to the occlusal plane, whereas the posterior teeth are
either vertical or incline slightly lingually.
• The mandibular ridge resorbs primarily from the occlusal
surface.
• Because the mandible is wider at its inferior border than at the
residual alveolar ridge in the posterior part of the mouth,
resorption, in effect, moves the left and right ridges
progressively farther apart

63. CHANGES IN MAXILLA AND
MANDIBLE
• The mandibular arch appears to become wider,
while the maxillary arch becomes narrower.
• Thus, RRR is centripetal in maxilla and centrifugal
in mandible.

65. EPIDEMIOLOGY OF RRR
• To date, it would appear that RRR is world-wide,
occurs in males and females, young and old, sickness
and in health, with and without dentures and is
unrelated to the primary reason for the extraction of
the teeth (Caries / periodontal disease).
• Rate of RRR is variable
• between persons.
• within the same person at different times.
• within the same person at different sites.

66. • There have been no large scale studies of RRR
• Longitudinal cephalometric studies of few subjects
have been done
• Studies also suggest that knife edge tendency (KET) in
mandibular residual ridge in women is more
compared to men.
KET = Change in area / Change in height

67. DIAGNOSTIC AIDS TO DETECT RRR
• Serial examinations of diagnostic casts
• Radiographs:
- Cephalometrics
- Panoramic.
• Tetracycline labelling
• Mercury porosimetry

68. CONSEQUENCES OF RRR
• Apparent loss of sulcus width and depth.
• Displacement of muscle attachment close to the
ridge.
• Loss of vertical dimension of occlusion.
• Increase in relative prognathia
• Changes in inter alveolar relationship following
RRR
• Morphological changes of the alveolar bone such
as sharp, spiny uneven residual ridges.
• Location of mental formina close to the ridge crest.

69. MANAGEMENT OF RRR
• Systemic evaluation
• Diet
• Tissue treatment therapy
• Pre prosthetic surgery
• Prosthetic management
• Impression techniques
• Teeth selection and arrangement
• Overdenture
• Implant supported prosthesis

70. SYSTEMIC EVALUATION
• Any systemic condition that can
contribute to the degeneration of the
bone condition should be corrected
and stabilized, for e.g.: osteoporosis,
hyperparathyroidism, diabetes
mellitus.
• Any dental treatment should follow
only after the condition is under
control and the patient is fit for
treatment.

71. DIET
• Patients with bone disease need a
diet high in proteins, vitamins and
mineral content.
• Should reduce alcohol and caffeine
intake.

72. TISSUE TREATMENT THERAPY
• Soft conditioning materials can be used
to rejuvenate the tissue-bearing area.
• Hypertrophied tissues, previously
treated by surgery, can be
reconditioned by using this material.

73. STIMULATION OF EDENTULOUS
AREAS
• Exercise stimulation is a practical & desirable part of complete
denture therapy.
• Exercise stimulation for a period of 12 weeks is usually adequate
in most severe cases.
• Intermittent use of exogenous pulsed electromagnetic fields has
demonstrated the effectiveness in decrease in the rate of
residual ridge resorption

74. PRE – PROSTHETIC SURGERIES
• It includes the following surgical procedures:
Ridge correction.
Ridge extension/vestibuloplasty.
Ridge augmentation

75. RIDGE CORRECTIVE SURGERIES
Soft tissue deformities
• Labial frenectomy.
• Lingual frenectomy.
• High buccal frenal attachments.
• Hyperplasia of soft tissues.

76. Bony deformities
• Sharp irregular ridge.
• Alveoloplasty.
• Alveolectomy.
• Excision of tori and genial tubercles
Ridge extension surgery/vestibuloplasty
• Labial.
• Lingual.
• Tuberoplasty.

77. Ridge augmentation
• Increase in the ridge height and width providing a large
denture bearing area
• Protection of neuro vascular bundles
• Restoration of proper maxillomandibular arch
relationship.
Ridge augmentation has been tried with:
• Bone transplants
• Autogenous cartilage
• Hydroxyapatite

78. PROSTHODONTIC MANAGEMENT
• Impression techniques
• Teeth selection and arrangement
• Overdentures
• Implant supported prosthesis

79. IMPRESSION TECHNIQUES
• In patients with severely resorbed ridges, lack of ideal
amount of supporting structures decreases support.
• The encroachment of the surrounding mobile tissues onto
the denture border reduces both stability and retention.
• Thus the main aim of the impression procedure is to gain
maximum area of coverage.
• Selection of proper trays and the correct impression
procedure is very essential for an accurate impression.

80. • Selective pressure technique
- This technique is most widely advocated to manage
RRR.
- It makes it possible to confine the forces acting on the
denture to the stress bearing areas .
-This helps in better withstanding the mechanical forces
induced by denture wearing.
- Adequate relief of non stress bearing areas .

81. - Winkler describes a technique which uses tissue
conditioners.
• An over extended primary impression of alginate is
made. Denture bases with occlusal rim were fabricated
on primary cast.
• Jaw relations were done to record appropriate
horizontal and vertical dimensions.
• Tissue conditioning material was applied on the tissue
surface of mandibular denture base
• patient was asked to close the mouth in the
prerecorded vertical dimension and do various
functional movements.

82. • 3 applications of conditioning material are used – each
application approximately 8-10 minutes.
• The third and final wash is made with a light bodied
material.
• This technique results in the impression that has tissue
placing effect with relatively thick, buccal, lingual and
sublingual crescent area borders.

83. • McCord & Tyson (BDJ 1997) - Use of
admixed technique for impressions :
• Impression compound and green tracing stick
compound in the ratio of 3 : 7 parts by weight
• placed in a bowl of water at 60°C and kneaded to a
homogenous mass
• provides a working time of about 90 seconds
• patient is made to do various tongue movements.

84. • All Green Technique :
• Mandibular impression was made using all green
technique.
• Green stick compound was kneaded to a
homogenous mass and was loaded on the special tray
and border movements were done.
• Final impression was made using zinc oxide eugenol.

85. • Elastomeric technique :
• A putty material is loaded along the borders of special
tray.
• The special tray is placed in the mouth and is border
molded; the patient is asked to move the tongue
according to standard impression procedures.
• The tray is removed from the mouth, and the impression
is examined.
• Light-body impression material is loaded in the
impression and inserted in the mouth.
• The patient is instructed to repeat the tongue
movements, light-body impression material is border
molded along the buccal and labial flange areas.

86. Cocktail technique
Praveen G., Gupta, S., Agarwal, S., & Agarwal, S. K. (2011). Cocktail Impression Technique: A New Approach to Atwood’s Order VI
Mandibular Ridge Deformity. The Journal of Indian Prosthodontic Society, 11(1), 32–35.

89. TEETH SELECTION AND ARRANGEMENT
The selection and arrangement of posterior teeth plays a
significant part in the retention and stability of dentures and
the conditions of supporting tissues.
(1) Buccolingually narrow teeth are used to reduce the
masticatory forces per unit area of the ridge.
(2) The width of the artificial teeth should be half of the natural
teeth.
(3) Non anatomic or zero degree posterior teeth should be
used to eliminate the horizontal forces and thus provide
increased stability to the denture.

90. (4) Acrylic teeth are used in preference to porcelain teeth as
acrylic teeth are easy to adjust and transmit less forces to the
supporting structures.
(5) Arrange the teeth to get a bilateral occlusion in the neutral
zone.

91. PROPER DESIGN OF DENTURES AND
MAINTENANCE
• Optimal tissue health prior to making impression.
• Broad area of coverage helps in reducing force per unit
area.
• Decreased buccolingual width of teeth will decrease the
amount of force required to penetrate a bolus of food.
• Avoidance of inclined planes to minimise dislodgment of
dentures and shear forces.
• Centralisation of occlusal contacts to increase stability and
maximize compressive forces.

92. • Adequate inter-occlusal distance during jaw rest to
decrease the frequency and duration of tooth contact.
• Resilient denture lining materials helps in transmission
of less force/unit area.
• A number of problems can results from errors in the
occlusion. Soreness may develop on the crest of the
residual ridges from the pressures created by heavy
contacts of opposing teeth in the same region.
• Correction of occlusion is necessary in this case.

93. OVERDENTURES
• Teeth supported over dentures helps in
improved stress distribution thereby
maintaining the integrity of residual ridge.
• The occlusal and parafunctional stresses
are distributed through the abutment
teeth.
• A study was conducted with
overdentures supported by canines and it
was seen that, the bone loss was 0.6mm
where as 5 mm in conventional complete
dentures.

94. IMPLANT SUPPORTED PROSTHESIS
• According to Morris et al, residual ridge
resorption in implant supported prosthesis
on the mandibular ridge was less compared
to the conventional denture for over a period
of 5 years
• The use of implant-supported overdentures
resembles the same clinical situation of teeth
supported overdentures.

95. Review of literature

96. Effect of mucostatic and selective pressure impression techniques on residual
ridge resorption in individuals with different bone mineral densities: A
prospective clinical pilot study
Tripathi et al. J.Prosth.Dent.2018
• Purpose. The purpose of this prospective clinical pilot study was
to objectively evaluate the effect of complete dentures
fabricated by different impression techniques on mandibular
residual ridge resorption in individuals with different bone
mineral density.
• Material and methods. Ninety-six participants with edentulism,
underwent bone mineral density assessment and were divided
into normal, osteopenic, and osteoporotic groups.
• Half of the participants in each group were provided with
dentures fabricated by selective pressure impression technique
(subgroup SIT), and the other half were provided with dentures
fabricated by mucostatic impression technique (subgroup MIT).

97. • Computed tomographic scans of the mandible were made at
denture delivery and 1 year after prosthesis use to assess
alveolar bone height and width difference at marked locations
at and after denture delivery.
• RESULTS
No statistically significant differences (P>.05) in mandibular
residual ridge height or width were found between
subgroups.

98. CONCLUSION
• RRR is reduced for dentures fabricated using mucostatic
impression technique compared with the selective pressure
impression technique in patients with diminished bone density.

99. Association between occlusal force distribution in implant
overdenture prostheses and residual ridge resorption.
Khuder T,. Journal of Oral Rehabilitation. 2017 May;44(5):398-404.
• AIM
• This study aimed to compare residual ridge resorption (RRR) of
anterior and posterior maxillary and mandibular edentulous ridges, in
patients treated with mandibular implant overdentures (IOD) and
compare with conventional complete dentures (CD).
• METHOD
• The anterior and posterior RRR of IOD (6 males, 17 females) and CD
(12 males, 11 females) were determined using baseline and follow-up
dental panaromic radiographs (DPT.
• The bone ratios were calculated using proportional area; anatomic to
fixed reference areas, and mean difference of ratios between the
intervals determined RRR.
• The ridge locations included anterior and posterior maxillary and
posterior mandibular arches. The T-Scan III digital occlusal system,
was used to record anterior and posterior percentage occlusal force
(%OF) distributions.

100. RESULT
• A total of 46 edentulous individuals (23 in each group)
participated in this study; and the results showed no significant
differences in patients’ demographic variables between IOD and
CD.

101. Residual Ridge Resorption in Complete Denture Wearers
Samyukta et al , J. Pharm. Sci. & Res. Vol. 8(6), 2016, 565-569
• AIM
• To find out the rate of ridge resorption by wical and swoop
method

102. Materials and Methods
• 60 completely edentulous subjects with age between
50 – 85 years, completely edentulous for more than 6
months were selected for the study. A standardized
panoramic radiograph was made for all patients.
Measurements were made digitally and the amount of
resorption was calculated using the Wical and Swoope
method.

103. CONCLUSION
• With an increase in age, there is an increase in the amount of
resorption.
• For a particular period of edentulousness, as age is
increased, there is an increase in the amount of resorption.
• The amount of resorption in females is found to be more
than that of male.
• In males and females, as duration of edentulousness
increases, there is an increase in the amount of resorption.
• Duration of edentulousness has the most significant impact
on resorption followed by age and then gender.

104. The effects of fixed and removable implant-stabilised prostheses on
posterior mandibular residual ridge resorption.
Clinical Oral Implants Research. 2002 Apr;13(2):169-74
• AIM
This study investigated the change over time in the area of the
posterior mandibular residual ridge in patients wearing either i)
mandibular overdentures ii) mandibular fixed cantilever
prostheses stabilised on five or six implants.

105. • CONCLUSION
In conclusion, this study has demonstrated low rates of
posterior mandibular resorption rates in patients with
advanced posterior resorption who were stabilised with
implant retained overdentures.

106. Effect of serum vitamin D, calcium, and phosphorus on mandibular residual
ridge resorption in completely edentulous participants: A clinical study
Kalavathy et al.J.Prosth.Dent. 2020
• AIM
The purpose of this clinical study was to evaluate the degree of
mandibular residual ridge resorption in completely edentulous
participants and to investigate the role of dietary nutrients in the
resorption process.
• MATERIAL AND METHODS
• Three hundred (55% men and 45% women; aged between 35 and 85
years) completely edentulous participants.
• A standardized panoramic radiograph was made, measurements
were made digitally, and the amount of resorption was calculated
using the Wical and Swoope method.

107. • The blood plasma levels of vitamin D3 were analyzed by using
the direct competitive chemiluminescence immunoassay (CLIA)
method,
• The total calcium and phosphorus were determined by using
spectrophotometer method.
• RESULTS

108. CONCLUSIONS
1. A strong influence of serum vitamin D3, calcium, and
phosphorus levels was found on mandibular residual ridge
resorption.
2. Mandibular residual ridge resorption increased as the level of
serum vitamin D3, calcium, and phosphorus decreased.
3. No association was found between age and serum vitamin D3,
calcium, and phosphorus levels.
4. No association was found between sex and serum vitamin D3,
calcium, and phosphorus levels.
5. Age and sex were found to be least associated with
mandibular residual ridge resorption.

109. PROSTHODONTIC MANAGEMENT OF RESIDUAL RIDGE
RESORPTION BY CONVENTIONAL METHODOLOGIES INCLUDING
NEUTRAL ZONE AND LINGUALIZED OCCLUSION SCHEMES:
REPORT OF TWO CASES
Sonali et al.Journel of critical reviews.2020
• AIM
• This paper presents report of two cases wherein prosthodontic
management of residual ridge resorption has been attempted
by neutral zone technique and lingualized occlusion scheme.
• CASE REPORT (NEUTRAL ZONE)
• A 48-year-old female patient with complaint of difficulty in chewing
for the past 6 years.

110. Plaster index placed to conform
the neutral zone

112. • CASE REPORT [LINGUALIZED OCCLUSION]
• A 64 year old male patient with highly resorbed lower anterior
ridge Atwood’s class V (Low Well Rounded) reported to the
department of prosthodontics of the institution.
• Patient was an old denture wearer.

114. CONCLUSION
• Recording the neutral zone is a quick, reliable, non-invasive and
economic technique that greatly improves denture stability.
• The benefit of neutral zone technique for denture fabrication is
that, it stabilizes the denture with the surrounding tissues,
instead of dislodging it.
• Lingualised occlusion redirects vertical forces more centrally on
the mandibular alveolar ridge, resulting in enhanced stability of
the lower denture.

115. PATTERN OF POSTERIOR RESIDUAL RIDGE RESORPTION UNDER
MANDIBULAR IMPLANT HINGING OVERDENTURES: A 5 –YEAR
RETROSPECTIVE STUDY
Elsayed et al.Egyptian Dental Journel.2017
• Purpose: This 5-year retrospective study aimed to investigate
and compare the effect of bar designs of two-implant-retained
overdentures (2-IRO) on pattern of the residual ridge resorption
(RRR) of the posterior mandibles using 3-D Cone Beam
Computed Tomography (CBCT) imaging.
• Materials and Methods:
• Forty five edentulous patients treated with mandibular 2-IRO
opposing maxillary complete denture were selected for the
study.
• According to bar designs; the enrolled patients were divided
into three groups: Group BC (n=19) patients treated with two
implant overdentures retained by a bar joint with a plastic

116. • Group BL (n=14) patients treated with two-implant
overdentures retained by locator attachments on the top of
milled bar.
• Group BD (n=12) patients treated with two-implant
overdentures retained by a straight bar with a plastic retentive
clip & distally cantilevered ball attachments.
• The pattern of posterior RRR was evaluated by using CBCT
imaging after 5 years post-treatment.
• RESULT
• For group BL, no significant differences were revealed in height
and width (for both buccal and lingual sides) of alveolar bone
when comparing molar and premolar areas.
• For group BD, the reduction in RRR recorded highly significant
differences

117. • CONCLUSION
Mandibular posterior residual ridge resorption occurs irrespective
of 2-IRO design.
The impact of bar design on the rate of residual ridge resorption
is a matter of controversy.

118. CONCLUSION
• As prosthodontists, we need to perform the most
meticulous prosthodontic care of edentulous patients.
• More research is needed on RRR to find better
methods of prevention or control of the disease to
provide best possible oral health care.

119. REFERENCES
• Essentials of complete denture-Winkler
• Syllabus of Complete Denture-Heartwell
• Prosthodontic treatment for edentulous patient-Boucher
• Clinical Dental Prosthetics-Fenn
• Levin B: impressions for complete dentures.
• Ortman HR: Factors of bone resorption of the residual ridge. J
Prosthet Dent 1962;12,3:429-440.
• Atwood DA: Reduction of residual ridges: A major oral disease
entity. J Prosthet Dent 1971;26:266-279.
• Atwood DA : Post extraction changes in the adult mandible as
illustrated by microradiographs of midsagittal sections and serial
cephalometric roentgenograms. J Prosthetic Dent 1963;13:810-824

120. THANKYOU