RESIDUAL RIDGE RESORPTION

GUIDED BY : DR.A.S. KAULPROF &HEAD OF

DEPT OF PROSTHODONTICSK.D.D.C., MATHURA

Presented by:- Preety dagar

29th june 2009

CONTENTS

INTRODUCTION BASIC CONCEPT OF BONE DEFINITIONS ETIOLOGY PATHOLOGY PATHOPHYSIOLOGY PATHOGENESIS

EPIDEMIOLOGY

TREATMENT & PREVENTION OF RRR

SUMMARY

BIBLIOGRAPHY

INTRODUCTION Anatomic changes will invariably take place

within the alveolar processes of the jaws following dental extractions. After the extraction of teeth, the empty dental alveoli fill up with blood, which sequentially clots,which is organized, and is replaced with new bone. To this newly formed ridge dentures are constructed, and the ridge undergoes changes in shape and reduces in size . The ridge changes occur because of the changes in the whole distribution of forces after the extraction. Over the long period of time, with the use or without the use of dentures there is the atrophy of the residual alveolar ridge or REDUCTION OF RESIDUAL RIDGE.

BASIC CONCEPT OF BONE THE STRUCTURAL ELEMENTS OF BONE

ARE:

1)OSTEOCYTES:-Are found in bony lacunae.

Responsible for metabolic activity of bone .

2)OSTEOBLASTS:-Active bone forming cells.During bone formation some osteoblasts become engulfed in intercellular substance and become osteocytes

3)THE INTERCELLULAR SUBSTANCE:-Bone matrix consist of fibrils and calcified cementing substance. Consist mainly of polymerized glycoprotein Mineral salts namely calcium and phosphate

are bound to these protein substances

4)OSTEOCLASTS:-Responsible for bone resorption.

Normal bone is in constant state of flux.

Bone is never static but rather there is contantly rebuilding, resorbing and remodelling subject to functional and metabolic stresses.

FOUR MAIN LEVELS OF BONE ACTIVITY

LEVELS

EQUILIBRIUM:-The two antagonists actions are in

balance.

ATROPY:-Decrease

osteoblastic activity as in

osteoporosis and disuse atropy.

RESORPTION:-Caused by

increase osteoclastic

activity.

GROWTH:-Increase

osteoblastic activity help in remodelling of bone as they

grow.

The normal equilibrium may be upset and pathological bone loss may occur if either bone resorption is increased or bone formation is decreased or if both occur.jpd;1962;12(3);441-450

Bone resorption always require the simultaneous elimination of organic and inorganic components of intercellular substances.

RESORPTION

Organic component Inorganic component

Proteolytic action Chelating action of of osteoclasts osteoclasts

As resorption takes place ,osteocytes released may revert to osteoblasts or osteoclasts depending on the physiological or pathological demands at that time.

Weinman and sicher(6) have proposed three possible causes of bone resorption:-

1)Aging with necrosis of bone.

2)Increase in pressure in adjacent tissue namely

Periosteum and bone marrow.

I

3)Direct action of the elements of the blood and tissue fluids.

Changes in chemistry of bone play a dominant part as a stimulus for fibrocytes from connective tissue and osteocytes from bone to metamorphose into osteoclasts and to commence resorption.

DEFINITIONS Residual ridge resorption :- A term used for

the diminishing quantity & quality of residual ridge after teeth are removed. (G.P.T -8)

Residual ridge :- The portion of the residual bone & its soft tissue covering that remains after the removal of teeth. (G.P.T -8)

Residual bone :- That component of maxillary & mandibular bone that remains after the teeth are lost. (G.P.T -8)

RESIDUAL RIDGE RESORPTION

RRR : A MAJOR

ORAL DISEASE ENTITY

ETIOLOGY

PATHOGENESIS

EPIDEMIOLOGY

TREATMENT AND

PREVENTION

PATHO-

PHYSIOLOGY

PATHOLOGY

RRR is a multifactorial disease.

Rate of RRR depends not only on one single factor but on the concurrence of two or more factors which may be called cofactors.

COFACTORS

ANATOMIC

METABOLIC FUNCTIONAL

PROSTHETIC

ANATOMIC FACTORS

RRR varies with quantity and quality of bone of residual ridges.

RRR α ANATOMIC FACTORS AMOUNT OF BONE QUALITY OF BONE:-

AMOUNT OF BONE

More the amount of bone,more will be the RRR.

But the amount of bone is not a good prognosticator of the rate of RRR.

If a low depressed ridge has existed for many years, future RRR will be at a low rate.

Tracing of cephalometric roentgenograms of 18 patients

reveal:variations in shape & size of jaws. jpd;1962;12(3);441-450

FACIAL MORPHOLOGY : ( JPD; 1979;41(1) 90-100)

The longer the face, the more alveolar bone there is and the less chance there is for an individual to reach a stage of severe atrophy in wearing dentures.

The further closed the vertical dimension of occlusion, the more compressive are the forces applied on the residual ridges and the greater are the chances for an individual with a closed vertical dimension of occlusion to reach the stage of extremely severe atrophy with the dentures, especially for the mandible.

MANDIBULAR SHAPE : ( JPD; 1972; 27(2)120-132)

Correlations between the shape of the mandible and the anterior mandibular bone loss indicated a pronounced resorption in subjects with a marked mandibular base bend, and a less marked resorption in subjects with a flattened mandibular base.

QUALITY OF BONE:- Mclean & urist (5) state that a loss of 24-

30% of bone salt is necessary to produce a appreciable change in x-ray of bone.

The denser the bone ,faster the rate of resorption because there is more bone to be resorbed per unit of time.

METABOLIC FACTORS

RRR varies directly with certain systemic or localized bone resorbing factors & inversely with bone formation.

RRR α BONE RESORBING FACTORS BONE FORMATION FACTORS

Therefore certain local bone resorbing factors could be very important.

These factors include:- Endotoxins from dental plaque

Osteoclasts activating factors

Prostaglandins

Human gingival bone resorption stimulating factor.

Heparin :-shown to be a cofactor in bone resorption.

observed in microscopic sections of residual ridge close to bony margin.

Other possible local bone resorption factors could be related to trauma(especially under ill fitting denture)which leads to increase or decrease in vascularity & change in oxygen tension.

Whatever the local resorbing factors may be they must be considered in the environment of systemic factors that influence the balance beween bone formation &bone resorption.

Systemic factors:-

Hormonal influences Dietary influences on bone on bone

Hormonal influences on bone

Hormonal influence is important to dentist because they involve the general health of patient which is reflected in the oral cavity.

1)Pituitary gland:-The anterior pitutary gland release ACTH.

ACTH protein catabolism

Interferes with the formation

of organic bone matrix .

causes

2)Thyroid gland:-regulates the rate of metabolism. Hyperthyroidism increases the metabolic rate

negative nitrogen balance

protein deficiency

osteoporosis

Thyroxine :- increases excretion of calcium & phosphorus,which leads to osteoclastic activity.

3)Parathyroid gland:-influence the excretion of phosphorus in kidney & directly influence osteoclasts.

parathormone maintains blood calcium level by mobilizing it from bone by osteoclastic activity

Islets of langerhans:-decrease insulin ,which leads to decrease utilization of glucose ,which in turn causes diabetes mellitus.

Poor healing of tissue

Rapid resorption of bone

Low tissue tolerance

Gonads:-Anabolic hormone(estrogen & testosterone) & antianabolic(cortisone & hydrocorticosone)

According to Reifenstein (5),in young person there is predominance of anabolic hormone, resulting in continued growth & maturation of skeleton.

In adult the anabolic & antianabolic hormones are in balance ,with the result that bone formation & bone resorption are in equilibrium ,and bone mass remains constant.

In older people the anabolic hormones are so reduced that the antianabolic hormones are in relative excess, bone resorption takes place faster than bone formation & bone mass is reduced.

The relationship of steroid hormone to the development & treatment of osteoporosis. jpd;1962;12(3);441-450

DIETARY FACTORS

VITAMIN A:-It influence the activity & position of osteoblasts & osteoclasts.

VITAMIN B COMPLEX:-Produce effect similar to protein deficiency.

essential for normal cell metabolism including bone cell.

VITAMIN C:-Bone matrix formation Vitamin c deficiency leads to:-

collagen content of bone is decreased

loosening of teeth .

disorganization of periodontal fibres & membrane.

Periosteum is affected in similar way :-it thickens & cell appear immature & resemble fibroblasts.

This condition may make the periosteum more easily injured by denture base.

Therefore ,inflamatory process are triggered by the denture base at lower pressure level.

VITAMIN D:-necessary for maintaining the calcium phosphorus level.

Pathologic bone disorders

Osteoporosis :-due to insufficient formation of the organic matrix.

Disturbance of protein metabolism & involve vitamin ,hormone & nutritional factors.

Usually found in edentulous mouth.

Osteomalacia :-faulty calcification of organic matrix. Results from faulty calcium metabolism

influenced by vitamin D & parathyroid glands.

Osteitis fibrosa :-normal cementing substance is replaced by fibrous tissue. It is usually a result of

hypeparathyroidism.

Periodontal disease is related to prosthetic problems,because both are concerned with differences in bone factor between different individual.

Stress regardless of its cause always produce a alarm reaction which increase the rate of bone resorption.

:-Protein balance is lost by dual effect of stress.

Age & sex are other factors which influence bone resorption.

FUNCTIONAL FACTORS

The remodelling of bone is influenced by force factors.

RRR α FORCE When considering force one must concern

about:- Amount of force Frequency of force Duration of force Direction of force Area over which force is distributed(force per unit

area) Damping effect of underlying tissue.

REACTION OF BONE TO PRESSURE AND TENSION:-

Is paradoxic since it can cause both apposition and resorption.

Within the physiologic limit Beyond the physiologic limit

APPOSITION

BONE RESORPTION

PRESSURE

Denture bearing bone has a complex blood supply from :

1) Internal from interdental arteries :-main supply pass through canals in intraalveolar septa

2) Externally from periosteum

Interference with blood supply leads to bone necrosis.

There is tendency for more RRR in mandible than maxilla.

Woelfel et al(1) have cited a patient with projected maxillary denture area of 4.2inches sq. And projected mandibular denture of 2.3inches sq.

Ratio is 1.8:1

If such patient bites with a pressure of 50lb

This calculates pressure of 12 lb/inches sq in maxilla & 21 lb/inches sq under mandibular denture.

This shows the difference in RRR of two jaws.

The amount of force applied to the bone is inversely proportional to damping effect or energy absorption.

RRR α I DAMPING EFFECT

:-Damping effect may take places in mucoperiosteum which can be considered a viscoelastic material

:-since the overlying mucoperiosteum varies in its viscoelastic properties from patient to patient &from maxilla to mandible ,its energy absorption qualities may influence the rate of RRR.

Frost (1)has stated that “bones which are subjected largely to compression loads & experience no significant bending loads are composed largely of cancellous bone which is ideally constructed for the absorption & dissipation of energy.”

The fact that the maxillary residual ridge is frequently broader,flatter & more cancellous than mandibular couterpart & may be a factor in frequenty observed differences in RRR of two jaws.

Resistance offered by hard palate play an role in less resorption of upper ridge.

Frost(1) points outs that trabeculae when oriented parallel to direction of compression deformation allows for maximal resistance to deformation.

Neufeld(1) cut the dry human jaws at right angles through the crest of ridge & demonstrated that the trabeculae were oriented at right angle to the crest & thus parallel to occlusal forces transmitted through the denture.

Gibbs et al(1) reported that 2o individual with healthy dentition bit with an average force of 162 lbs & 5 edentulous patient with an average force of 35lbs.overall loading of edentulous mandible is less than dentulous mandible.

Disuse atropy & fracture are examples of extremes of functional forces.

DISUSE ATROPY

The deficiency is in the formation of the new protein matrix with no disturbance of calcification.

Atropy of disuse is directly proportional to the extent of disuse.

After the loss of the natural teeth,the bone cannot be stimulated by a denture base as the teeth did internally.

This loss of internal stimuli & reduction of closing force are signals for disuse atrophy & a remodeling of bone in accordance with WOLFF ‘S LAW OF TRANSFORMATION(6)

Prosthetic factors

The traditional design of denture includes many features whose goal is to reduce the amount of force to ridge &thereby to reduce RRR.

The prosthetic factors include:-

Broad area coverage (to reduce force per unit area)

Decrease bucco-lingual width of teeth.

Decreased number of dental units

Improved tooth form(to decrease the amount of force required to penetrate a bolus of food)

Avoidance of inclined plane(to minimize dislodgement of denture & shear forces)

Centralization of occlusal contacts(to increase stability of denture )

Provision of adequate tongue room(to improve stability of denture in speech & mastication)

Adequate interocclusal distance during rest jaw relation (to decrease frequency & duration of tooth contact).

For convenience ,since the functional

factors must function through the prosthetic factors ;they may be grouped together as mechanical factors.

In addition to three major categories ,the importance of time since extraction to bone loss should be emphasized in inverse relation.

RRR α ANATOMIC FACTORS + FORCE FACTORS DAMPING

EFFECT + BONE RESORPTION FACTOR BONE FORMATION FACTOR + 1 TIME

PATHOLOGY OF RRR

GROSS PATHOLOGY:- A lay man expression of RRR is” my gums

have shrunk”.

Basic structural changes in RRR is reduction in size of bony ridges under the mucoperiosteum.

It is primarily localized loss of bone structure

In some situations ,this loss of bone may leave overlying mucoperiosteum excessive and redundant.

LAMMIE(1) has postulated that one factor in RRR may be a cicatrizing mucoperiosteum that is seeking a reduced area, resulting in pressure resorption of underlying bone.

Numerous longitudinal radiographic cephalometric studies have provided excellent visualization of the gross pattern of bone loss from a lateral view point.

The superimposition of tracing of three lateral cephalographs which clearly show the reduction in size & shape that occurs on external surface on the labial,crestal & lingual aspect of residual ridge.jpd;1971;26(3);266-279

The study of morphologic changes in facial skelton during seven years of complete denture wear revealed that there is decrease in facial height due to :- jpd;1972;27(2);120-132 Pronounced reduction of mandibular ridge Forward & upward rotation of mandibular

ridge

The changes in mandibular position was accompanied by a marked increase in mandible prognathism.

Despite alterations in jaw relations ,no dimensional changes were found in the cranial base ,the upper part of face,or the basal part of mandible.

Gross anatomic studies were done on dried jaw bone which have shown a wide variety of shape & size of residual ridge.

The residual ridge is categorized in 6 orders:-

I ORDER – PRE EXTRACTIONII ORDER - POST EXTRACTIONIII ORDER – HIGH , WELL ROUNDEDIV ORDER - KNIFE EDGEV ORDER- LOW ,WELL ROUNDEDVI ORDER - DEPRESSED

This classification is helpful clinically as well as for research purposes &help one to differentiate the various stages of RRR in individual patient . jpd;1971;26(3);266-279

:- Panoramic radiograph described by wical & swoope (3)provide a graphic picture of bone resorption ,particularly of mandible.

:-But in films of edentulous patients ,the only remaining radiographic landmarks in body of mandible are the superior & inferior border of bone & the mental foramen .

:-Mental foramen is taken as a reference point .

Three measurements were recorded on panoramic radiograph of jaws of adult subjects :-1)from the inferior border to superior border of

the alveolar bone.

2)from the inferior border of mandible to lower edge of foramen.

3)from the inferior border to upper edge of the foramen .

Films of 130 subjects met the criteria & were used in the study.

Relationships measured on radiographic image of normal mandible

The mean ratio between the total height of mandible & the height of lower edge of the foramen in 260 samples was 2.90:1 with a standard deviation of 0.23

The mean ratio between the total height of the mandible & the height of upper edge of the foramen in 260 samples was 2.34:1, with a standard deviation of 0.20.

Clinically the lower edge of the mental foramen appears to be more useful reference mark in panoramic radiograph.

By measuring the distance from inferior border of the mandible to the lower edge of foramen & using the approximate ratio of 3:1;the original length of mandible before resorption can be estimated.

Method of estimating the original height of atrophied mandible

Based on method of estimating bone loss there are three divisions used for epidemiological studies are:-

1. Class I –Upto one third of original vertical height lost

2. Class II – From one third to two third of vertical height resorbed

3. Class III – two thirds or more of vertical height resorbed lost

MICROSCOPIC PATHOLOGY

Microscopic studies have revealed evidence of osteoclastic activity on external surfaces of residual ridge .

The scalloped margin of howship’s lacunae sometimes contain visible osteoclasts.

A microradiographic study of 21 edentulous mandible has shown variation in :-

Density of osteons

Number of incompletely closed osteons

Endosteal porosity

Number of plugged osteons.

PATHOPHYSIOLOGY RRR is a localized pathologic loss of bone

that is not built back by simply removing the causative factors.

Physiologic process of internal bone remodeling goes on even in the presence of pathologic external osteoclastic activity.

A modified version of ENLOW V(2) principle of bone remodelling illustrate dramatically the mechanism of reduction of mandibular residual ridge by external resorption accompanied by endosteal deposition.

Structurally , the configuration of endosteal bone is dependent upon the configuration of the bony surface on which the inward endosteal bone is deposited.

Thus endosteal bone may be characterized by a convoluted whorled appearance if the bone growth is in a trabecular area or by a zone of even ,regular ,uninterrupted circumferential lamellae if the bone is laid on endosteal side of smooth cortical bone.

The type of bone commonly found on the crest of ridge appears to be endosteal bone of the whorled convoluted type due to the compacting of trabecular bone by the deposition of layers of new bone on old trabeculae.

As the endosteal bone become compacted ,it is invaded by resorption spaces & new haversian systems are formed within the compacted bone.

PATHOGENESIS

After the extraction of tooth ,any sharp edges remaining (order II) are rounded off by external resorption leaving a high well rounded ridge(orderIII).

As resorption continues from the labial & lingual aspect ,the ridge becomes increasingly narrow ultimately becoming knife edge (orderIV).

As resorption continues further,the knife edge ridge becomes shorter & eventually disappear ; leaving a low, well rounded or flat ridge(orderV).

Eventually this too resorbs leaving a depressed ridge.(order VI)

The reduction of residual ridge is chronic , progressive , irreversible & cumulative.

The reduction of residual ridge usually proceeds slowly over a long period of time from one stage to next.

Within a given individual the rate is usually most rapid in first six months following extraction. jpd ;1971;26(3);266-279

The RRR curves in one subject studied over a 19 yrs period illustrates various principles of variation within a given subject. jpd;1971;26(3);266-279

The anterior vertical RRR in maxilla was 3mm during the first 3yrs & immeasurable thereafter.

While in mandible ,after a dramatic early bone loss ; it continues to show a steady reduction rate i.e. 0.4mm/year to a total of 14.5mm in 19yrs.

The longitudinal study of edentulous individuals covering 25 years of complete denture wearing revealed a continued reduction of the residual ridges throughout the observation period . Jpd;1972;27(2);120-132

The mean reduction in anterior height of bony alveolar ridges of group A during 13.5 yrs of complete denture wearing & in group C between the 10year & 25year stages of denture wearing.

The mean rate of reduction in anterior height of maxillary alveolar ridge in group A & C jpd;1972;27(2);120-132

The mean rate of reduction in anterior height of mandible alveolar ridge in

group A & C jpd;1972;27(2);120-132

In group A the mean decrease in anterior height of the lower ridge between the seven year and 13.5 year controls was 1.4 mm and that of the upper ridge was 0.4 mm

The mean decrease in mandibular height during the total period of 13.5 years was 7.7 mm, and the maxillary reduction was 2.2 mm.

In group C the mean reduction in anterior height of the lower residual ridge between the 10 year and 25 year stages of denture wear was 3 mm and that of the upper ridge was 0.8 mm.

In both sample , the mean reduction in anterior height of the lower ridge during the follow up period was about four times greater than that of upper ridge(4:1).

The magnitude of alveolar resorption showed great individual variation jpd;1972;27(2);120-132

The tracings show the bony contour of anterior residual ridge at the stage of insertion , at 1year, 7year, & 13.5 year stages of observation.

The marked alveolar bone loss during the first year of denture wearing and the gradual decrease in the rate of resorption is clearly noticeable.

Tracing of anterior bone loss of lower ridge between 10 & 25 yrs stages of complete

denture jpd;1972;27(2);120-132

EPIDEMIOLOGY

It is the study of distribution & determinants of disease in man.

It can contribute to an understanding of the etiology of a specific disease .

There have been no large scale studies of RRR in man.

Most studies till today have been meticulous longitudinal cephalometric studies of relatively few subjects.

Such studies are time consuming & expensive & not really good examples of epidemiologic methodology.

The panoramic method , however , could be used to screen large population of edentulous subjects.

RRR is a world wide disease ,occurs in males & females, young & old ,in sickness & in health ,with & without dentures; & is unrelated to the primary reason for extraction of teeth.

One vertical study made measurements on casts & calculated mean differences in residual ridge size in a group of patients ,some of whom wore denture & some of whom did not .

In this investigation ,there seemed to be a difference in mean size of ridges between the two groups ,but within each group there were wide variations

The more statistically significant an association between a determinant & disease , the more likely there is meaningful relationship.

However such relationship is not necessarily a casual association because both the determinant & the disease may have been caused by other determinants.

Following factors tend to obscure the etiology of a disease:- Sometime a disease is caused by single

determinant , sometime by multiple factor

The resistance of host to causative factors may affect the frequency or severity of disease.

Sometime a certain dose of causal factor is necessary to cause a disease.

Sometime a casual factor must be present a certain length of time to be effective.

Therefore, until one gathers sufficient evidence one must first develop a hypothesis & then test this hypothesis by appropriate means.

DIFFICULTY IN STUDYING RRR

1)The disease is almost universal,but there are variation in amount & rate between individuals.

2)The amount is cumulative so that a single examination does not reveal the present rate.

3) The rate is slow , therefore lengthy longitudinal studies are required to determine the rate.

4)The rate may vary at different times & in different sites within an individual . Therefore repeated readings at intervals are needed to reveal changes in rate.

5)The rate is very likely to be dependent, not on a single factor , but on coexistence of several factors.

6)Not all cofactors are easily measured.

7)It is possible that not all cofactors are even being considered.

TREATMENT AND PREVENTION

SWENSON(4) stated, “ The ideal ridge is one that is broad in its bearing surface and has practically parallel sides.”

But in the degenerative denture ridge, undercut ridges, V- shaped ridges, thin knife edge ridges, and flat or non- existent denture ridges may be seen.

Prosthodontists must correct dentures on all of these degenerated ridges and should aim not only to replace the lost structures and lost function but also to preserve the remaining ridge.

PREPARATION OF MOUTH :- Patients with degenerate denture ridges

need careful mouth health restoration before construction begins.

1. Physical health :- Any systemic illness that is contributing to the degenerate bone condition must be corrected or stabilized.

2. Diet :- One of the most neglected facets of treatment in degenerate denture ridge patients is the prescribing of a diet.

These patients need a diet high in protein, vitamin, and mineral content.

3. Tissue treatment therapy :- The use of soft conditioning material to rejuvenate the tissue bearing area has been well established.

PROCESSED, RESILIENT, LINED DENTURE BASES

Its greatest advantages are its cushioning effect upon the mucosa and its ability to distort and spring back.

It is really indicated in the cases of 1. Severely undercut ridges where surgery

is contraindicated2. Patients with no ridge3. Patients with a flat ridge and delicate

tissues.4. Spinous ridge, tori, the mental foramen,

and the genial tubercles

The lining is best when there is a 2 mm thickness. So, it cannot be used in the cases of small interridge distance.

The biggest disadvantage is deterioration of the resilient liner in few months

ARTICULATING METHODS :- Success or failure of treatment of the degenerate ridge patient is dependent on a good occlusion and occlusal vertical dimension.

If rehabilitation of the articulator apparatus is impossible, teeth with a flat occlusal pattern are best.

SELECTION OF OCCLUSAL PATTERNS :- The patient with impaired chewing ability should have non-anatomic posterior teeth.

The most important factor in articulation is that centric occlusion be harmonious with centric relation.

A balanced occlusion is important for denture base stability

POST INSERTION CARE :- The delicate tissues will require many

adjustments. These should be done carefully with a

pressure sensitive paste. A periodic assessment of the denture and

the ridge is advocated. It is best to see these patients every 72 hours for atleast three appointments.

These patients should be seen at regular intervals of at least every six months.

SUMMARY

Reduction of residual ridges needs to be recognized for what it is: a major unsolved oral disease which causes physical, psychological, and economic problems for millions of people all over the world. RRR is a chronic, progressive, irreversible, and disabling disease, probably of multifactorial origin. Much is known about the pathology and pathophysiology of this oral disease, but we need to know much more about its pathogenesis, epidemiology, and etiology. The ultimate goal of research of RRR is to find better methods of prevention or control of the disease. So, more research in RRR with new methods and new thinking are badly needed in order to provide the best possible oral health care for millions of edentulous patients.

BIBLIOGRAPHY 1) SHELDON WINKLER : ESSENTIALS OF COMPLETE

DENTURE PROSTHODONTICS – SECOND EDITION

2) DOUGLAS ALLEN ATWOOD : REDUCTION OF RESIDUAL RIDGES : A MAJOR ORAL DISEASE ENTITY; 1971; 26(3);266-279

3) WICAL AND SWOOPE : STUDIES OF RESIDUAL RIDGE RESORPTION. USE OF PANORAMIC RADIOGRAPHS FOR EVALUATION AND CLASSIFICATION OF MANDIBULAR RESORPTION; ; 1974;32(1); 7-12

4) DOUGLAS C. WENDT : THE DEGENERATIVE DENTURE RIDGE – CARE AND TREATMENT; 1974; 32(5);477-492

5) DOUGLAS ALLEY ATWOOD : SOME CLINICAL FACTORS RELATED TO RATE OF RESORPTION OF RESIDUAL RIDGES ;1962;12(3) ;441-450

6) HAROLD R. ORTMAN : FACTORS OF BONE RESORPTION OF THE RESIDUAL RIDGE ; 1962 ;12(3); 429-440

7)ANTJE TALLGREN:THE CONTINUING REDUCTION OF RESIDUAL ALVEOLAR RIDGE IN COMPLETE DENTURE WEARERS:A MIXED LONGITUDINAL STUDY COVERING 25YEARS;1972;27(2);120-132

8)PAUL MERCIER :RESIDUAL ALVEOLAR RIDGE ATROPY :CLASSIFICATION AND INFLUENCE OF FACIAL MORPHOLOGY ;1979;41(1);90-100.

THANK YOU

Masticatory & non masticatory force is transmitted to dentoalveolar bone through periodontal ligament.

Once teeth are removed the residual alveolar ridge is subjected to entirely different types of forces.

Bassett(1) has suggested that mechanism by which force is translated into bone remodelling (wolff’s law) may be through a bioelectric properties of bone.