RESIDUAL

RIDGE

RESORPTION

Guided by:

Dr. Manesh Lahori

Prof. & Head

Presented by:

Varun Gupta

P.G. Student

CONTENTS

•Introduction.

•Basic concept of bone.

•Mechanism of bone resorption

•Pathology of RRR

•Pathophysiology of RRR

•Pathogenesis of RRR

•Changes in maxilla and mandible

•Epidemiology of RRR

•Etiology of RRR

•Calcium homeostasis and RRR

•Osteoporosis and RRR

•Management of RRR

•Summary

•Conclusion

•References

INTRODUCTION

Residual ridge is a term used to describe the

shape of the clinical alveolar ridge after healing of

bone and soft tissues after tooth extractions. It

consists of the denture-bearing mucosa, submucosa

and periosteum, and the underlying residual

alveolar bone.

•After tooth extraction, a cascade of inflammatory reactions is

immediately activated, and the extraction socket is temporarily

closed by the blood clot.

•Epithelial tissue begins its proliferation and migration within the

first week and the disrupted tissue integrity is quickly restored.

•The most striking feature of the extraction wound healing is that

even after the healing of wounds, the residual alveolar ridge bone

undergoes a life-long catabolic remodeling.

•The size of the residual ridge is reduced most rapidly in the

first 6 months, but the bone resorption activity continues

throughout life at a slower rate, resulting in removal of a large

amount of jaw structure.

•This unique phenomeneon has been described as RESIDUAL

RIDGE RESORPTION (RRR).

•The rate of RRR is different among persons and even at

different sites in the same person.

The mechanical aspect of bone remodeling is usually associated with

Wolff’s law of bone transformation (1892) which states that “Every

Change In The Form And Function Of Bone , Or Of Their Function

Alone,is Followed By Certain Definite Changes In Their Internal

Architecture, And Equally Definite Alteration In Their External

Conformation, In Accordance With Mathematical Laws.”, which

simply means that bone remodels in response to the forces applied.

However, the mere reference to ‘Wolff’s law’ in relation to bone

resorption is an inadequate explanation of this complex physiologic

process.

Consequences of RRR

•Apparent loss of sulcus width and depth.

•Displacement of the muscle attachment closer to the crest of the

residual ridge.

•Loss of vertical dimension of occlusion.

•Reduction of lower face height.

•An anterior rotation of the mandible.

•Increase in relative prognathia.

•Changes in inter-alveolar ridge relationship.

•Morphological changes such as sharp, spiny, uneven residual ridges.

•Resorption of the mandibular canal wall and exposure of the

mandibular nerve.

•Location of the mental foramina close to the top of the mandibular

residual ridge.

This provides serious problems to the clinician on how to provide

adequate support, stability and retention of the denture.

Basic concept of bone:

A basic concept of bone structure and its functional

elements must be clear before bone resorption can be

understood. The structural elements of bone are:

a) Osteocytes found in bone lacunae.

b) The intercellular substance or bone matrix consisting of

fibrils and calcified cementing substance.

c) Osteoblasts.

d) Osteoclasts

(a) OSTEOCYTES:

These are small, flattened and rounded cells embedded in the

bone lacunae.

They are the main cells, of the developed bone and are derived

from the matured osteoblasts.

Function:

• Help to maintain bone as a living tissue because of their

metabolic activity.

• Play an important role in maintaining the exchange of calcium

between bone and extra cellular fluid.

(B) CALCIFIED CEMENTING SUBSTANCE:

Consists of mainly polymerized glycoproteins and mineral salts

namely CaCo3 and phosphate which are bound to these protein

substances.

(C) OSTEOBLASTS:

Concerned with bone formation and are situated on the outer surface

of bone in a continuous layer.

Functions:

• Responsible for synthesis of bone matrix.

• Role in calcification.

(D) OSTEOCLASTS:

They are the giant multinucleated cells found in the lacunae of bone

matrix.

Functions:

• Responsible for bone resorption during bone remodeling. Bone

resorption always requires the simultaneous elimination of organic

and inorganic components of the intercellular substance.

MECHANISM OF BONE RESORPTION

•The organic components of the intercellular substance are

removed by proteolytic action of the osteoclasts.

•Then, 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 possible the bone balance of shape

and size.

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

localized loss of bone structure. In some situations, this loss of bone

may leave the overlying mucoperiosteum excessive and redundant.

In order to provide a simplified method for categorizing the most

common residual ridge configurations, a system of six orders of RR

form has been described.

Order 1 - Pre extraction

Order 2 - Post extraction

Order 3 - High, well-rounded

Order 4 - Knife edge

Order 5 - Low, well-rounded

Order 6 - Depressed

•It is clear that 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.

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.

PATHOPHYSIOLOGY OF RRR

•It is a normal function of bone to undergo constant

remodeling throughout life through the process of bone

resorption and bone formation.

•Growth : ↑ Bone formation.

•Osteoporosis/localized periodontal disease: ↑ Bone resorption.

RRR is a localized 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.

•It has been shown that remodeling takes place in 3 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 is replaced by a new cortical layer that

is formed by simultaneous endosteal bone formation.

•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.

Based on the clinical fact that :

•RRR is not inevitable

• Its rate varies

• The rate of resorption is greater that the rate of formation in some

patients ,

….RRR should be considered a pathologic process.

Pathogenesis of RRR

Order I: pre-extraction: The tooth is in its socket with thin labial and

lingual cortical plates merged with the lamina dura.

Order II: postextraction: The healing period includes clot formation and

organisation, filling of the socket with the trabecular bone and

epithelisation over the socket site. The edges of the residual ridge are

still sharp.

Order III: High , well rounded residual ridge: The cortical plates are

rounded off by external osteoclastic resorption, narrowing of the crest of

the ridge begins and remodelling of the internal trabecular structure takes

place.

Order IV: Knife edge RR : Sharp narrowing of the labio-lingual

diameter of the crest of the ridge with a compensatory internal

remodelling leading to a sharp crest of the ridge.

Order V: Low well rounded RR : Progressive labio lingual narrowing

of knife edge ridge leads to a widely rounded and lower residual

ridge.

Order VI: Depressed RR: Eventually further progression of the

resorption leads to a flat, depressed ridge.

•RRR is chronic, progressive, irreversible and cumulative.

Usually, RRR proceeds slowly over a long period of time

flowing from one stage imperceptibly to the next.

•Autonomous regrowth has not been reported. Annual

increaments of bone loss have a cumulative effect leaving

less and less residual ridge.

Changes In The Maxilla

And The Mandible

•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 resorbs primarily from the occlusal

surface and from the buccal and labial surfaces.

•Thus the maxillary residual ridge looses height and

maxillary arch becomes narrower from side to side and

shorter anteroposteriorly.

•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.

•The mandibular arch appears to become wider, while the maxillary

arch becomes narrower.

•Thus, RRR is centripetal in maxilla and centrifugal in mandible.

•The cross section shrinkage in the molar region, is downward and

outward. In the anterior region it is first downward and backward

,and then moves forward.

•The surface of the arches maybe resorbed out of parallelism which

can result in diminished stability of dentures.

•Severe ridge resorption can also result in increased inter arch

space.

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 diff. times.

-within the same person at diff. sites.

ETIOLOGY OF RRR

It is postulated that RRR is a multifactorial,

biomechanical disease that results from a

combination of:

• Anatomic

• Metabolic

• Functional

• Prosthetic factors

ANATOMIC FACTORS

It is postulated that RRR varies with the quantity and quality of

the bone of the residual ridges:

RRR α anatomic factors

1. The amount 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.

•Although the broad ridge may have a greater potential for bone

loss, the rate of vertical bone loss may actually be slower than

that of a small ridge because there is more bone to be resorbed

per unit of time and because the rate of resorption also depends

on the density of bone.

2. 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 of time.

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

In equilibrium the two antagonistic actions (of

osteoblasts and osteoclasts) are in balance. In growth, although

resorption is constantly taking place in the remodeling of bones

as they grow, increased osteoblastic activity more than makes

up for the bone destruction.

Whereas in osteoporosis, osteoblasts are hypoactive,

and, in the resorption related to hyperparathyroidism, increased

osteoblastic activity is unable to keep up with the increased

osteoclastic activity. The normal equilibrium may be upset and

pathologic bone loss may occur if either bone resorption is

increased or bone formation is decreased, or if both occur.

Since bone metabolism is dependent on cell metabolism,

anything that influences cell metabolism of osteoblasts and

osteoclasts is important.

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.

•The degree of absorption of Ca, P and proteins determines the

amount of building blocks available for the growth and

maintenance of bone.

•Vit C aids in bone matrix formation.

•Vit D acts through its influence on the rate of absorption of

calcium in the intestines and on the citric acid content of bone.

•Various members of Vit B complex are necessary for bone cell

metabolism.

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 antianabolic 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.

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.

•It does not result from the direct loss of non functional bone, but

the lack of replacement of bone not needed for function.

•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.

•The amount and frequency of stress and its distribution and

duration are important factors.

•The reaction of bone to pressure can cause both apposition and

resorption

•Whenever pressure interferes with the blood or nerve supply of the

bone, resorption occurs.

•The interference maybe due to pressure directly from the bone or

inflammatory in origin.

PROSTHETIC FACTORS

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:

• Abused tissues are always manifested with a slung, glistering

surface. 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 .

Long continued use of ill fitting dentures:

• In ill fitting dentures, there is an improper relation of the

denture base to the supporting tissue. Ill fitting dentures may be

due to :

• Long use

• Loss of bone

• Incorrect occlusion

• Incorrect jaw relation

Under extended dentures:

• Lead to less retentive dentures and increase load per

unit area. Common sites are:

• Lingual flange

• Buccal shelf area

• Retromylohyoid area

• Retromolar pad

Faulty improper procedures employing compression forces:

• 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, away from the tissues. If it

is too small, the border tissues will collapse inward onto the

residual ridge. This will reduce the support of the lips 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

otherwise.

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. It is normally 2-8mm but in complete dentures it is around

2mm. At times, due to lack of freeway space the bone resorbs because

of increased vertical height in an attempt to create the space.

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,

during eccentric movement, it causes pressure on bone due to failure

of denture stability. Hence resorption of base occurs.

Faults in selection and placement of posterior teeth:

The selection of proper tooth size is based on :

•Capacity of ridges to receive and resist the forces of

mastication.

•Space available for the 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 minimize the forces directed to such a ridge.

If occlusal corrections are not done:

• These errors which may be caused due to processing techniques if not

corrected causes premature contacts resulting in increased stress.

• Selective grinding should be done to minimize lateral stress and

resulting tissue trauma.

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 .

Bone resorption and Ca homeostasis:

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 develops, resorption is stimulated and factors that would inhibit

resorption are depressed.

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.

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 may be a manifestation of Type I osteoporosis .

•Both cortical and trabecular bone are affected.

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 and injections and calcitonin to reduce

resorption.

Detection of bone loss i.e. radiographs

•Digital subtraction radiography

•Dual energy x-ray absorptiometry

Methods of evaluation of bone loss in RRR

• Radiographs:

- Cephalometrics

- Panoramic

• Tetracycline labeling

• Mercury porosimetry

• Anatomic studies

• Remount jig procedure

Management of RRR

Systemic evaluation

Diet

Tissue treatment therapy

Pre prosthetic surgery

Prosthetic management:

-Impression techniques.

-Denture base selection.

-Teeth selection and arrangement.

-Implant supported prosthesis.

1. 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.

•In cases where limited help can be given, the patient should be

counseled about its effect on dental health.

2. Diet

•Patients with bone disease need a diet high in proteins, vitamins

and mineral content.

•Should reduce or stop intake of refined carbohydrates, white

flour, and white sugar.

•In all dietary prescriptions , the consistency of food prescribed

must take into account the patients ability to masticate.

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.

Pre-prosthetic surgery

It aims at providing a good healthy surface for the insertion of the

dentures.

It includes all the surgical procedures by virtue of which an ideal

smooth, healthy U shaped ridge , without any unfavourable

undercuts or bony growths and with sufficient vestibular depth is

achieved.

It includes the following surgical procedures:

•Ridge correction.

•Ridge extension/vestibuloplasty.

•Ridge augmentation

•Surgical correction of maxillomandibular relation.

Ridge Corrective surgery

Soft tissue deformities

•Labial frenectomy.

•Lingual frenectomy.

•High buccal frenal attachments.

•Hyperplasia of soft tissues.

Bony deformities

•Sharp irregular ridge.

•Alveoloplasty.

•Alveolectomy.

•Excision of tori and genial tubercles.

Ridge extension surgery/vestibuloplasty:

•Labial.

•Lingual.

•High mental foramen.

•Zygomaticoplasty.

•Tuberoplasty.

Ridge augmentation

It is aimed at :

•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 and homogenous cartilage

•Hydroxylapatite

•Acrylic implants.

PROSTHETIC MANAGEMENT.

1). Impression technique

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. 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

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.

• Winkler describes a technique which uses tissue conditioners.

An over extended primary impression of alginate is made.

• Occlusal wax rims are constructed and the borders are adjusted

so that the lingual flange and sublingual crescent area are in

harmony with the resting and acting phases of the floor of the

mouth by an open and closed – mouth technique.

3 applications of conditioning material are used – each

application approximately 3-10 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.

Miller used mouth-temperature waxes instead of tissue

conditioners.

Mucodynamic technique

It is intended to integrate the changes in the shape of the

vestibules when functional movements are made. A highly viscous

thermoplastic reversible impression material is placed in the custom

tray, then carefully adapted to the residual ridge and held with light

and uniform pressure while the functional movements are made. As

soon as the entire surface is smooth and the buccal and lingual

borders are molded to the outer circumference without any folds, the

impression is complete.

2. Selection of denture base

For degenerative ridge patients there are three types of denture bases:

•Methyl methacrylate resin denture bases

•Cast metal bases

•Processed resilient , lined denture bases

Methyl methacrylate resin denture bases

•These are the standard bases normally used.

•These bases are quickly and easily processed.

•Dimensionally stable.

•But in a short time the base appears to soften and change color, and is

not strong.

Cast metal bases

Main advantage is the great accuracy of fit to the tissues

by surface tension, than acrylic denture bases.

They maybe of gold, chromium cobalt or aluminium.

Processed resilient , lined denture bases

Its greatest advantage is its cushioning effect on the mucosa and

its ability to distort and spring back.

Indications:

•Patients with severely undercut ridges, but for whom surgery is

contraindicated.

•Patients with parafunctional mandibular movement habits.

•Patients with flat ridge and delicate tissues.

Limitations

They can be used only under a hard-processed acrylic

resin base, and the lining works best when there is a 2 mm

thickness.

Deterioration of the liner in some mouths.

In spite of this , it can be held up well in dentures by proper

cleansing and brushing with soft tooth brush.

Teeth selection and arrangement

Teeth can be selected acc. to their form and size:

•Anatomic or cuspal teeth

•Semi anatomic teeth

•Non anatomic or zero degree teeth.

The following requirements have to be met during teeth

arrangement:

•Stability of occlusion in centric relation.

•Balanced occlusion for eccentric contacts.

•Unlocking of the cusps mesio distally to accommodate the

settling of denture bases.

Control of horizontal force by buccolingual cusp height reduction

acc. to residual ridge shape and inter arch space.

Functional balance by favorable tooth to ridge crest position.

Cutting and shearing efficiency.

Anterior clearance of teeth during mastication.

Minimal occlusal stop areas for reduced pressure during function.

Teeth should be placed in neutral zone to create co ordination

between the primary and secondary masticatory organs.

Relative to each other, the maxillary and mandibular residual

ridges are known to be in a favorable position for normal

arrangement of posterior teeth if the connecting line between the

midridge line of the max. and mand. residual ridges are at an angle

of more than 80 degrees.

An angle less than 80 degrees necessitates a cross bite or

reverse occlusion arrangement of posterior teeth.

A prognathic mandible necessitates the arrangement of

anterior teeth in a reverse occlusion.

•Non anatomic teeth have known to cause fewer denture sore

spots and lesser ridge resorption

•Semi anatomic reverse curve posterior teeth favor the lower

ridge

•Anatomic posterior teeth cause more denture soreness and

ridge resorption

•Few studies state that anatomic posterior occlusion favors

lower dentures and non anatomic posterior teeth favor upper

denture.

Implant Supported Prosthesis

The various problems associated with RRR and stability of

removable soft tissue borne dentures have aroused interest in dental

implantology to provide stable mechanical support to the dental

prosthesis.

This is because of the following advantages offered by

implant supported prosthesis:

Maintenance of alveolar bone.

Maintenance of occlusal vertical dimension.

Height of alveolar bone is found to be maintained as long as the

implant remains healthy.

Improved psychological health.

•Regained proprioception.

•Increased stability, retention and phonetics.

•Maintenance of structure and function of muscles of mastication

and facial expression.

•Immune to caries.

•Increased trabeculation and density of bone.

•Overall volume of bone is maintained.

•Efficiency to take up stress and strain.

•There is 20 fold decrease in the loss of structure with implants

when compared with resorption that occurs with removable

prosthesis.

•Preventive implant is given following extraction to retard ridge

resorption.

PROSTHODONTIC CLASSIFICATION OF

IMPLANTS

FP-1 : Fixed prosthesis replacing only crown.

FP-2 : Fixed prosthesis replacing crown and portion of root.

FP-3 : Fixed prosthesis replacing missing crowns and portion of

the edentulous site.

RP-4 : Removable prosthesis : overdenture supported by

implants.

RP-5 : Removable prosthesis : overdenture supported by both

soft tissue and implant.

The success of implant supported prosthesis, however,

depends on the technical knowledge and mastery of the

implantologist, and is directly related to the selection of patient

and implant, surgical technique, follow up procedures and

patient acceptability.

SUMMARY

Residual ridge resorption is a chronic, progressive,

irreversible, and disabling disease , of multifactorial origin.

Much is known about its pathology and pathophysiology,

but a lot remains to know about its pathogenesis, epidemiology

and etiology.

RRR requires a multiple approach for diagnosis and

treatment planning.

The cause must be detected, by the aid of a physician, and

then eliminated or stabilized before dentures are constructed.

Construction of a stable functioning denture and a regular

follow up treatment can help in the restoration of function, and thus,

the restoration of the physical and mental vitality of the patient.

Conclusion

•The preservation of supporting tissues is a sacred trust that

cannot be ignored.

•The application of the basic concepts and the advances made in

the basic sciences will help to keep this trust in the hands of the

dental profession.

As prosthodontists, we need to perform the most

meticulous and intelligent prosthodontic care of the patient

within our capabilities.

…and then , it would not seem a nebulous hope that some day

there will be control over residual ridge resorption.

•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: Some clinical factors related to rate of resorption of

residual ridges. J Prosthet Dent 2001;86:119-125.

•Wendt DC: The degenerative denture ridge – Care and treatment.

J Prosthet Dent 1974;32,5:477-492.

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Thank you