Resisual Ridge Resorption

Presented by:
Dr. Jehan Dordi
1st Yr. MDS
RESIDUAL RIDGE RESORPTION
1

CONTENTS
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• Introduction
• Pathology of RRR
• Microscopic pathology
• Pathophysiology of RRR
• Pathogenesis of RRR
• Epidemiology of RRR
• Etiology of RRR
• Treatment of RRR
• Review of Literature
• References

4
According to GPT 9:
• Residual bone – “It is 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.”

Bone Density:
5
• When a tooth is lost, the alveolar bone starts to lose dimensions and
density.
• MacMillan in 1926 states "Levels of bone density are directly related
to stress, the greater the physiologic stress, the denser the bone.”
• The longer time span the alveolar bone is edentulous, the less
trabeculae are present.
• This disease begins within few months, continues for long term and
affects both cortical and trabecular bone.

6
Branemark and Zarb – listed 4 types of bone qualities in jaw bone:-
• Quality 1 – Is comprised of homogenous compact bone.
• Quality 2 – Has a thick layer of compact bone surrounding a core of
dense trabecular bone.
• Quality 3 – Has a thin layer of cortical bone surrounding dense
trabecular bone of favorable strength.
• Quality 4 –Has a thin layer of cortical bone surrounding a core of
low-density trabecular bone.

7
According to Misch bone may be classified into 4 macroscopic
decreasing density groups.
• D1 – Dense cortical bone
• D2 – Thick dense to porous cortical bone on crest and coarse trabecular bone
within
• D3 – Thin porous cortical bone on crest and fine trabecular bone within
• D4 – Fine trabecular bone

8
The density is determined with radiographs and CT provides the
data in Hounsfield units:
• D1: more than 1250
• D2: 850–1250
• D3: 350–850
• D4: 130–350
Carl E. Misch. Contemporary implant dentistry. 2nd edition.

9
• Anatomical location of bone types:
• Anterior maxilla – D2 and D3 bone
• Posterior maxilla – D3 and D4 bone
• Anterior mandible – D1 and D2 bone
• Posterior mandible – D2 and D3 bone
Carl E. Misch. Contemporary implant dentistry. 2nd edition.

10
• According to Winkler following the extraction of teeth, the empty
dental alveoli fill up with blood, which sequentially clots, is
organized, and is replaced with new bone.
• The muco-periosteum, whether surgically apposed or not, covers
over the remaining alveolar bone and healing alveoli.
• It is a common fact that the residual ridges to which prostheses are
meticulously fitted change shape and are reduced in size at varying
rates in different individuals and in the same individual at different
times.

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• As a result of this treatment of the edentulous patient requires a
maintenance phase that must be carried out for the remaining life of
the patient.
• The degree of RRR is frequently so great that well constructed
complete dentures must be repeatedly relined or remade for functional
and esthetic reasons long before the dentures have worn out.

Resorption Pattern
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• Generally women show more RRR than men.
• During the first year following extraction, reduction in residual ridge
height is 2–3 mm in maxilla and 4–5 mm for mandible.
• After this, the process will continue but with reduced intensity.
Mandible shows 0.1–0.2 mm resorption annually, which is four times
more than edentulous maxilla.

Consequences of Residual Ridge Resorption
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• Apparent loss of sulcus width and depth.
• Displacement of muscle attachment closer to crest of the residual
ridge.
• Loss of vertical dimension of occlusion.
• Reduction in the lower face height.
• Anterior rotation of mandible and increase in relative prognathism.

14
• Mental foramen may come to lie at or near the level of the upper border
of the body of mandible.
• The genial tubercles project above the upper border of the mandible in the
symphyseal region.
• Flattening of the vault of the palate.
• Reduction in the height of both the maxillary and mandibular edentulous
arches.

15
• While the maxillary arch resorbs buccally
and labially with a concomitant reduction
in perimeter or circumference of the arch,
the mandibular arch resorbs in a labial and
lingual direction resulting in widening of
the arch posteriorly.
• This will lead to confinement of maxillary
arch within the mandibular arch in
longstanding edentulous situations, giving
a pseudo-class III ridge relationship

17
• RRR is primarily a localized loss of bone structure.
• Longitudinal radiographic cephalometric studies have provided
excellent visualization of the gross patterns of this bone loss from a
lateral viewpoint.
• The careful superimposition of portions of tracings of these lateral
cephalograms has clearly shown the gross reduction of bone in size
and shape that occurs on the external surface on the labial, crestal,
and lingual aspects of the residual ridge.

19
• In order to provide a simplified method for categorizing the most
common residual ridge configurations, a system of six orders of
residual ridge form has been described by Atwood (1963)
• Order I- Pre-extraction
• Order II- Post-extraction
• Order III- High, well rounded
• Order IV- Knife edge
• Order V- Low, well-rounded
• Order VI- Depressed

20
• Dry specimens of mandible shows that while external cortical
surfaces of the maxilla and mandible are uniformly smooth, the
crestal areas of residual ridges have a different appearance and show
more porosities and imperfections.

21
• Bones with the most severe RRR (Orders V and VI) may display the
gross porosity of medullary bone on the crest of the ridge and
eventually may even display the uncovering of the inferior alveolar
canal on the mandible.

22
• Grossly, this localized
pathologic process can
remove incredible
amounts of bone.
• Lateral cephalometric
radiographs provide the
most accurate method
for determining the
amount of residual ridge
and the rate of RRR over
a period of time

23
• RRR does not stop with the residual ridge, but may go well 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.

24
• The panoramic radiographic technique described by Wical and Swoope is a
simple, useful method for arriving at a gross estimate of the amount of RRR to
date in a given patient.
• Class I- Upto one third of the original vertical height lost.
• Class II- From one third to two third of the vertical height lost.
• Class III- Two third or more of the mandibular height lost.

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Resorptive pattern of the edentulous ridge (Mercier, 1995)
• Type I – Minor ridge modelling. The ridge becomes thin and
pointed.
• Type II – Sharp atrophic residual ridge. The pointed ridge flattens to
the level of the basal bone.
• Type III – Basal bone ridge. The flattened ridge becomes concave as
the basal bone resorbs.
• Type IV – Basal bone resorption.

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• Class I – Dentate
• Class II – Post-extraction
• Class III – Convex ridge form, with
adequate height and width of alveolar
process.
• Class IV – Knife edge form with
adequate height but inadequate width
of alveolar process.
• Class V – Flat ridge form with loss of
alveolar process.
• Class VI – Loss of basal bone that
may be extensive but follows no
predictable pattern.
Residual ridge form has been classified by Cawood an Howell as follows:

28
• Microscopic studies have revealed evidence of osteoclastic activity
on the external surface of the crest of residual ridges.
• The scalloped margins of Howship’s lacunae contain visible
osteoclasts.
• Frequently, the scalloped external surface seems inactive, without
visible bone-resorbing cells, and is covered by fibrous non-osteogenic
periosteum.

29
• A micro-radiographic study of edentulous mandibles has shown wide
variation in the configuration, density, and porosity.
• In addition, there was micro-radiographic evidence of mandibular
osteoporosis including:
a. Increased variation in the density of osteons,
b. Increased number of incompletely closed osteons,
c. Increased endosteal porosity, and
d. Increased number of plugged osteons in about half the specimens.

31
• The presence of smooth periosteal lamellar bone on the lingual,
inferior, and labial surfaces of the mandibles, but the total absence of
such lamellations on the crest of the residual ridge.

32
• Cortical layer consisting of an endosteal type of bone or else no
cortical layer but simply a medullary type of trabecular bone is also
seen.

34
• Osteoporosis is a generalized disease of bone in which bone is in
negative balance, because bone resorption exceeds bone formation.
• In periodontal disease, there is a localized destruction of the bone
around teeth, perhaps due to certain local pathologic processes.
• In both generalized osteoporosis and localized periodontal disease,
when bone matrix is lost it does not ordinarily return.
• The process of RRR has not been reversed till date, such that the
residual ridge has increased in size.

35
• 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 bone substance.
• Remodeling must take place in three dimensions such that certain
portions of bone become narrower to the extent that all existing
cortical bone in that area is removed by external osteoclastic activity.
• And it should be replaced by a new cortical layer that is formed by
simultaneous endosteal bone formation.

36
• Structurally, the configuration of endosteal bone is dependent upon
the configuration of the bony surfaces on which the inward endosteal
bone growth is deposited.
• Endosteal bone may be characterized by a convoluted whorled
appearance.
• If endosteal bone growth fails to keep pace with the external
osteoclastic activity, there will be absence of a cortical layer and
exposure of the medullary layer to the external surface of the bone,
resulting in defects on the crest of the ridge.

38
• Immediately following the extraction (Order II), any sharp edges
remaining are rounded off by external osteoclastic resorption, leaving
a high, well-rounded residual ridge (Order III).
• As resorption continues from the labial and lingual aspects, the crest
of the ridge becomes increasingly narrow, ultimately becoming knife-
edged (Order IV).

39
• As the process continues, the knife edge becomes shorter and
eventually disappears, leaving a low well-rounded or flat ridge (Order
V).
• Eventually, this too resorbs, leaving a depressed ridge (Order VI).
• RRR is chronic, progressive, irreversible, and cumulative.
• Annual increments of bone loss have a cumulative effect, leaving less
and less residual ridge.

41
• There have been no large-scale studies of RRR in man.
• Most studies of RRR have been meticulous longitudinal
cephalometric studies of a relatively few subjects.
• RRR is worldwide, occurs in males and females, young and old, in
sickness and in health, with and without dentures.
• It is unrelated to the primary reason for the extraction of the teeth
(caries or periodontal disease).

42
• Multiple other possible determinants do, explain the variations in the
rate of RRR between individuals which has not yet been elucidated.
• Sometimes a disease is caused by a single determinant, sometimes by
multiple factors.
• The resistance of the host to the causative or predisposing factors may
affect the frequency or severity of a disease.

44
• It is postulated that RRR is a multifactorial, biomechanical disease
that results from a combination of anatomic, metabolic, and
mechanical determinants.
• Since all of these factors may vary from one patient to the next, these
different cofactors may combine in an infinite variety of ways, thus
explaining the variations in RRR between patients.

Anatomic Factors
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• It is postulated that RRR varies with the quantity and quality of the
bone of the residual ridges.
• RRR ꝏ anatomic factor
• More bone there is, the more RRR there will ultimately be, but the
amount of bone is not a good prognosticator of the rate of RRR

46
• Clinicians should evaluate the present status of the residual ridge to
determine what has gone on before: that is, if a ridge has existed as
high and well-rounded (Order III) for several years, it will likely
continue to do so.
• If a residual ridge has gone from an Order II to an Order IV in a scant
two years, it will probably continue to resorb rapidly.
• If a low depressed ridge has existed thus for many years, future RRR
will probably be at a low rate.

47
• Another way to evaluate the anatomic factors is to consider the
mechanical factors that would be favorable to stability and retention
of a denture.
• Thus, large well-rounded ridges and broad palates would seem to be
favorable anatomic factors.

Metabolic Factors
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• RRR varies directly with certain systemic or localized bone resorptive
factors and inversely with certain bone formation factors:
• RRR is a localized loss of bone on the crest of the residual ridge.
• Local biochemical factors in relation to periodontal disease play an
important role in RRR.

49
• These factors include:
• Endotoxins from dental plaque,
• Osteoclast-activating-factor (OAF),
• Prostaglandins,
• Human gingival bone-resorption stimulating factor, and others.
• Heparin, a cofactor in bone resorption, is associated with mast cells,
and can be observed in microscopic sections of residual ridges close
to the bone margin.
• Other local bone resorption factors are related to trauma, which leads
to increased or decreased vascularity and changes in oxygen tension.

50
• Local bone resorbing factors must be considered in the environment
of the systemic factors that influence the balance between normal
bone formation and bone resorption .
• Some patients have a natural resistance to unfavorable local factors
whether it be
• Calculus or bacteria;
• Occlusal force in patients with natural teeth;
• Vertical dimension,
• Cusp form,
• Other prosthetic factors in denture wearers.

51
• Perhaps such individuals have the correct amounts of circulating:
• Estrogen,
• Thyroxine,
• Growth hormone,
• Androgens,
• Calcium,
• Phosphorus,
• Vitamin D,
• Protein,
• Fluoride, and so on to compensate for
poor local factors.
• Some patients maybe already in a negative bone balance owing to
some form of osteoporosis and may therefore be more vulnerable
to unfavorable local factors.

Mechanical Factors
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• 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.
• Masticatory and non-masticatory force is ordinarily transmitted to the
dento-alveolar bone through the periodontal ligament.
• Some postulate that RRR is an inevitable “ disuse atrophy .”

53
• Others postulate that RRR is an “ abuse” bone resorption due to
excessive forces transmitted through dentures.
• Hence both hypothesis are true which states with or without dentures
some patients have little or no RRR and some have severe RRR.
• It is not the amount of force that is taken into concern, but also
• The frequency of force,
• The duration of force,
• The direction of force,
• The area over which force is distributed and
• The damping effect of the underlying tissue.

54
• Abnormal parafunctional forces from clenching and grinding of teeth
may last up to several hours per day which likely leads to pathologic
loads on the residual ridges.
• Force is a cofactor in RRR that can be expressed as:
• There is a tendency for more RRR in the mandible than in the
maxilla.

55
• The amount of force applied to the bone may be affected inversely by
the “damping effect,” or energy absorption.
• This cofactor may be expressed as follows:
• The “damping effect” may take place in the mucoperiosteum which
can be considered a viscoelastic material.

56
• Muco-periosteum varies in its viscoelastic properties from patient to
patient and from maxilla to mandible, its energy absorption qualities
may influence the rate of RRR.
• Bones which are subjected largely to compression loads are
composed largely of cancellous bone, which is ideally constructed for
the absorption and dissipation of energy.
• Maxillary residual ridge is frequently broader, flatter, and more
cancellous than its mandibular counterpart and may be a factor in the
frequently observed differences in the RRR of the two jaws.

57
• The traditional design of dentures includes many features whose goal
is to reduce the amount of force to the ridge and thereby to reduce
RRR.
• These prosthetic factors include:
• Broad-area coverage
• Decreased number of dental units,
• Decreased bucco-lingual width of teeth,
• Improved tooth form
• Avoidance of inclined planes
• Centralization of occlusal
contacts
• Provision of adequate tongue
room
• Adequate inter-occlusal
distance during rest jaw

58
• For simplicity, only the major categories of cofactors are included
as follows:

Systemic Factors
59
Systemic factors that affect rate of RRR includes:
• Circulating estrogen
• Thyroxin
• Growth hormone
• Androgens
• Calcium
• Phosphorous
• Vitamin-D
• Protein
• Fluoride

60
Bone Loss due to decreased formation:
• Glucocorticoids markedly inhibits bone formation and causes severe
osteoporosis.
• Excess secretion of cortisol by the adrenal glands (Cushing’s
syndrome)
• Glucocorticoid therapy for treatment of diseases such as
rheumatoid arthritis

61
Bone loss due to increased resorption:
• Hypophosphatemia.
• Rarely occurs as a result of deficient phosphorus intake.
• May occur in patients with duodenal ulcers who are treated with
aluminum hydroxide gel, which binds phosphorus and renders it
unabsorbable.

62
Osteoporosis:
• Osteoporosis results from the loss of bone, especially the spongy
spicule that supports the weight bearing parts of the skeleton.
• It strongly affects reduction of the residual ridge in edentulous
patients.
• It is more common where heavy loads are present:
(e.g. in vertebral column, epiphyses of long bones, pelvis, the maxillae
and fingers).

63
Etiology of Osteoporosis:
• More common in aged female where blood estrogen level is dropped.
• Lack of calcium intake.
• Lack of calcium absorption due to:
i) Lack of HCl acid in stomach
ii)Gastric and duodenal acidity will be reduced in elderly this will cause lack of
absorption of Ca from milk and milk products which are rich sources of
calcium.

Prosthetic Factors
64
• Excessive loading of tight denture that produce rapid RRR
• Denture plaque
• Occlusal force (unstable occlusion)
• Uneven occlusal forces (e.g Combination syndrome)
• Decreased VD
• Cusp form (sharper cusps can increase force on the tissues)
• Tissue reaction,
• Ill fitting denture

Nutritional Factors
65
• Vitamins, minerals, and protein demands have potential beneficial
effects when properly oriented in the diet.
• A pan-vitamin program has prophylactic value.
• Adequate mineral intake must be assured for a normal bone picture.
• Protein is the most important nutritional factor in its effect on bone.
• An edentulous condition necessitates the protection of a high protein-
low carbohydrate diet.

Time
66
• RRR is unpredictable. The rate of resorption in the maxilla is lesser
than that of the mandible.
• Pattern of resorption:
• Resorption occurs more rapidly in the first six months after
extraction of teeth and at a slower pace till 12 months.
• The rate of resorption progresses after 65 years of age.
• Residual ridge resorb more rapidly in females than males.
• It can be precipitated by certain systemic diseases or ill-fitting
dentures.

68
• The depth and width of the sulcus is reduced due to the resorption of
the ridge till the level of the muscle attachment.
• Hence the muscles appear to be inserted on the crest of the ridge
obliterating the sulcus.
• Decreased vertical dimension at occlusion (VDO).
• Reduction of the lower facial height (due to decreased VDO).
• Anterior rotation of the mandible

69
• Increase in relative prognathism.
• Resorption is centripetal (towards the centre) in the maxilla, and
centrifugal (away from the centre) in the mandible.
• Hence, the size of the maxillary arch will decrease with resorption
and the size of the mandibular arch will increase with resorption.
• Sharp, spiny and uneven ridge appear in the crest due to difference in
rate of resorption from one place to another.
• Long-term resorption affects support stability and retention of
dentures.

70
Changes in the maxilla:
Resorption of the bone of the maxillae usually permits the upper
denture to move up and back in relation to its original position.
However, the occlusion also may force the maxillary denture forward.
Changes in the mandible:
The mandible will move to a higher position during occlusion
than the one it occupied before the resorption.
This will lead to a decrease in the inter-arch space. The
mandibular movement is rotatory around a line approximately passing
through the condyles.

71
• The effect of this rotatory movement varies from patient to patient
and appears to result from a complex interaction of several features
which includes:
• The duration and magnitude of bone resorption.
• The mandibular postural habit.
• Tooth morphology.
• The amount of material present.

72
• The mandible's rotation may produce the following consequences:
• Loss of centric occlusion in the dentures.
• Changes in the structures that support the upper denture.
• Movement of the lower denture in a backward direction. This
may lead to traumatic changes in the supporting structures of the
mandible.
• Movement of the lower jaw anteriorly, with an ensuing
prognathic appearance.

74
Following are the methods:
A) Improving the patients denture foundation and ridge relations:
i) Non-surgical methods
• Rest for denture supporting tissues
• Soft liner (Tissue conditioner)
• Massaging
• Remove old denture for 2 to 3 days prior to making impression for new
denture
• Occlusal and VD correction of old prosthesis
• Good nutrition
• Conditioning of patients musculature by jaw exercise.

75
ii) Surgical methods
• Correcting conditions that preclude optimal prosthetic function
• Localized or generalized hyperplastic replacement of resorbed
ridges.
• Epulis fissuratum
• Papillomatosis

76
• Unfavorably located frenular attachments
• Pendulous maxillary tuberosities
• Bony prominences, undercuts and ridge discrepancy in jaw size
relationship (exostosis should be removed before tooth extraction).
• Pressure on mental foramen.

77
• B) Enlargement of denture bearing area
• Vestibuloplasty
• Ridge augmentation
• C) Provision for placing tooth root analogues by means of
osseointegrated implants.

78
• The best way to manage the problem of residual ridge resorption is
by using every means to prevent it.
Impression techniques
• In patients with severely resorbed ridges, lack of ideal amount of
supporting structures decreases support and 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.

79
• For e.g., in mandibular ridge, obtaining a fairly long retromylohyoid flange
helps to achieve a better border seal and retention.
• Selection of proper trays and the correct impression procedure is very
essential for an accurate impression.
• Selective pressure 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.

McCord and Tyson’s admixed technique
80
• Impression compound and green tracing stick compound in the ratio
of 3 : 7 parts by weight are placed in a bowl of water at 60 C and
kneaded to a homogenous mass that provides a working time of
about 90 seconds.
• Wax spacer is removed; this homogenous mass is loaded and patient
is made to do various tongue movements.

All Green Technique
81
• Green stick compound is kneaded to a homogenous mass and is
loaded on the special tray and border movements are done.
• Final impression is made using zinc oxide eugenol.

82
Winkler’s technique (tissue conditioners)
• In this technique, denture bases with occlusal rim are fabricated on
primary cast.
• Jaw relations are done to record appropriate horizontal and vertical
dimensions.

83
• Tissue conditioning material is applied on the tissue surface of
mandibular denture base and patient is asked to close the mouth in
the prerecorded vertical dimension and do various functional
movements such as puffing, blowing, whistling, and smiling.
• Three applications of tissue conditioner material are done at an
interval of 8–10 minutes and functional movements are made by the
patients.
• Final impression is made with light body addition silicone material
with closed mouth technique.

Cocktail Impression Technique
84
• In this technique customized tray is fabricated with autopolymerizing
acrylic resin according to Dynamic Impression Technique.
• A tray with 1 mm wax spacer and cylindrical mandibular rests in the
posterior region is made at increased vertical height.
• Patient is advised to close his mouth so that the mandibular rests fit
against the maxillary alveolar ridge.
• This helps to stabilize the tray in position by preventing anteroposterior
and mediolateral displacement of the tray during definitive impression.

85
• Lingual surfaces of mandibular rests are made concave to provide
space for the tongue to move freely during functional movements.
• McCord and Tyson’s technique for flat mandibular ridges is followed
for definitive impression.

86
• For recording the functional state, patient is instructed to run his
tongue along his lips, suck in his cheeks, pull in his lips, and swallow
by keeping his mouth closed, as in closed mouth impression
technique, till the impression material hardens.
• The retrieved impression is visually inspected for surface
irregularities and disinfected and is poured in dental stone.

Elastomeric Technique
87
• Tray adhesive is applied over the border, internal and external surface
of the acrylic custom tray, to facilitate the retention of the silicone
border moulding material.
• An addition silicon putty with an extended working time is loaded
along the borders of special tray.
• The special tray is placed in the mouth and its border is molded; the
patient is asked to move the tongue according to standard impression
procedures.

88
• The tray is removed from the mouth, and the impression is examined.
• Light-body addition of silicon impression material is loaded in the
impression and inserted in the mouth.

89
• The patient is instructed to repeat the tongue movements, more
vigorously, while the light-body impression material is border
molded along the buccal and labial flange areas.
• After the material has set, the impression was removed from the
mouth and examined for any discrepancy

90
By Reducing the forces required to drive the denture teeth through the bolus
of food, this may be achieved by either increasing the denture bearing area or
reducing the size and altering the morphology of the occlusal table.
Increasing the denture bearing area:
• Although prosthodontic norms recommend full use of the functional denture
bearing area, this is rarely achieved.
• A consequence of this is that the smaller the size of the fitting surface of the
denture, the greater are the loads applied to the underlying mucosa.

91
• In such cases, the denture bearing area may be increased using green
stick impression compound before relining or by using a chairside
relining material prior to the denture being relined conventionally.
• Reducing the size and altering the morphology of the occlusal table:
• Clinical experience indicates that many complete lower dentures
have posterior teeth set without consideration of possible support
problems.
• In general, occlusal tables tend to be too large.

92
• This leads to problems of support and stability which in solo and in
combination, put too much pressure on the atrophic mucosa during
function.
• The combination of reduced occlusal table and if necessary, increased
denture bearing area can greatly reduce the load per unit area on the
underlying mucosa and improve denture comfort.

93
By Eliminating disruptive occlusal contacts which lead to denture
in stability.
• Disruptive occlusal contacts may present in any border position and
in 'normal' function as well as parafunction.
• Their detection and elimination must be carried out where changes in
VDO and elimination of such disruptive forces are indicated.

94
By use of implants for providing implant supported or implant
assisted prosthesis also helps avert continuing residual ridge
resorption.
• Clinicians must try to retain residual roots whenever feasible.
• Overdentures help minimize ridge resorption and contribute to
enhanced retention stability, support of prosthesis along with
preservation of proprioception.

Tripathi A, Singh SV, Aggarwal H, Gupta A. Effect of mucostatic and selective pressure
impression techniques on residual ridge resorption in individuals with different bone mineral
densities: A prospective clinical pilot study. The Journal of prosthetic dentistry. 2019 Jan
1;121(1):90-4.
96
• 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.
• Significantly less reduction in mandibular ridge height and width was
found in the MIT versus the SIT subgroups in both osteopenic and
osteoporotic participants.

97
• No significant subgroup difference was found for normal bone
mineral density group, although resorption increased in height and
width for the SIT subgroup.
• Mandibular residual ridge resorption was reduced for dentures
fabricated using the mucostatic impression technique compared with
the selective pressure impression technique in individuals with
diminished bone density.

Maruo Y, Nishigawa G, Irie M, Oka M, Hara T, Suzuki K, et al. Stress
distribution prevents ischaemia and bone resorption in residual ridge. Arch oral
Biol 2010;55:873-8.
98
• Intensive mechanical stress and/or inflammation are known to induce
alveolar bone resorption.
• This study investigated whether a distribution of mechanical stress
would reduce residual ridge resorption or improve ischaemia.
• Non-viscoelastic material clearly induced bone resorption and
ischaemia of denture foundations, while viscoelastic materials
reduced these phenomena to different extents according to their
viscoelastic properties.

99
• Ischaemia in the alveolar ridge preceded residual ridge resorption,
because the amount of residual ridge resorption and blood flow rate
showed a simple linear regression.
• Animal model of this study suggested that a distribution or reduction
of mechanical stress could improve blood flow and decrease alveolar
ridge resorption.

Makzoumé JE. Morphologic comparison of two neutral zone impression
techniques: A pilot study. The Journal of prosthetic dentistry. 2004 Dec
1;92(6):563-8.
100
• The purpose of this pilot study was to compare the outline form of
the phonetic and swallowing neutral zone impression techniques for
the same subjects.
• One method used phonetics and tissue conditioner to shape the
neutral zone; the second method used swallowing and modeling
plastic impression compound.
• The resulting neutral zone impressions were leveled to the same
occlusal height by gently grinding the occlusal surface on sandpaper
until it corresponded with landmarks

101
• The buccal contours of both neutral zones coincided at the median
line.
• The maximum distance between the zones was measured in a bucco-
lingual direction in the anterior, premolar, and molar regions
bilaterally.
• Significant differences were noted buccally in the left molar and right
molar regions and also in the left and right premolar regions where
the swallowing neutral zone was found to be located buccal to the
phonetic neutral zone.

102
• Significant differences were also noted lingually, in the right
premolar region where the swallowing neutral zone was found to be
located lingual to the phonetic neutral zone.
• There was no significant difference between the techniques for the
anterior region.
• Within the limits of this study, the phonetic neutral zone appears to
be narrower posteriorly compared to the swallowing neutral zone,
thus limiting premolar and molar positioning.

104
• Zarb Bolender, Eckert, Jacob, Fenton & Mericske stern.
Prosthodontic treatment for edentulous patients. 12th Edition. Mosby.
• John Sherry. Complete Denture Prosthodontics. 1st Edition. Mc-
Grawl Hill book company. New York :1962
• Sheldon Winkler. Essentials of Complete denture prosthodontics. 2nd
Edition. A.I.T.B.S publishers. New Delhi, India.
• Charles Heartwell, Arthur Rahn. Syllabus of Complete dentures. 4th
Edition. Varghese publishing house. Mumbai, India. 1992.
• Carl E. Misch. Contemporary implant dentistry. 2nd edition.
Elsevier. Boston, USA. 2013

105
• Tripathi A, Singh SV, Aggarwal H, Gupta A. Effect of mucostatic and
selective pressure impression techniques on residual ridge resorption
in individuals with different bone mineral densities: A prospective
clinical pilot study. The Journal of prosthetic dentistry. 2018 Jul 10.
• Kovacic I, Celebic A, Zlataric DK, Petricevic N, Bukovic D, Bitanga
P, et al. Decreasing of residual alveolar ridge height in complete
denture wearers: a five year follow up study. Coll Antropol
2010;34:1051-6.
• Maruo Y, Nishigawa G, Irie M, Oka M, Hara T, Suzuki K, et al.
Stress distribution prevents ischaemia and bone resorption in residual
ridge. Arch oral Biol 2010;55:873-8.

106
• Yadav B, Jayna M, Yadav H, Suri S, Phogat S, Madan R. Comparison
of different final impression techniques for management of resorbed
mandibular ridge: a case report. Case reports in dentistry. 2014;2014.
• Praveen G, Gupta S, Agarwal S, Agarwal SK. Cocktail impression
technique: a new approach to atwood’s order vi mandibular ridge
deformity. The Journal of Indian Prosthodontic Society. 2011 Mar
1;11(1):32.
• Makzoumé JE. Morphologic comparison of two neutral zone
impression techniques: A pilot study. The Journal of prosthetic
dentistry. 2004 Dec 1;92(6):563-8.

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