Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
GUIDED BY:
DR. MANESH LAHORI
PROFF & HEAD
DEPT. OF PROSTHODONTICS
KDDC, MATHURA
PRESENTED BY:
DR. PRATEEK AGRAWAL
M.D.S. I...
CONTENTS
• INTRODUCTION
• ETIOLOGY OF RIDGE RESORPTION
• CLASSIFICATION OF RESIDUAL RIDGE
• PREVENTION AND TREATMENT
• SUM...
INTRODUCTION
Residual ridge is a term used to describe the shape of
the clinical alveolar ridge after healing of bone and ...
The most striking feature of the extraction
wound healing is that even after the healing of
wounds, the residual alveolar ...
Residual ridge resorption after loss of
teeth is a multifactorial oral problem.
According to Atwood, the degree of mandibu...
Residual bone is considered to be the base
which provides support for dentures and is an
area where forces created while b...
ETIOLOGY OF RIDGE
RESORPTION
It is postulated that residual ridge resorption
is a multifactorial, biomechanical disease th...
A. Anatomic factors:-
Ridge resorption varies with-
 Quantity and Quality of the bone.
 Shape& Form of the ridges (Large...
B. Metabolic factors:-
• Generally, body metabolism is the net sum of all the building
up (anabolism) and the tearing down...
• Whereas in osteoporosis, osteoblasts are hypoactive,
and, in the resorption related to
hyperparathyroidism, increased os...
• Some local biochemical factors in relation to
periodontal disease which affects the ridge
resorption-
Endotoxins from d...
• Systemic factors influence the balance between the
normal bone formation and bone resorption. These
factors create a nat...
C. Mechanical factors:-
Functional Factors-
When force within physiologic limits is applied to
bone that force brings abo...
Damping Effect/ Energy Absorption-
Resorbing residual ridge is indirectly
proportional to damping effect. Dampening
effec...
D. Prosthodontic factors:-
Clinical observations indicate that excessive
alveolar bone resorption can be caused by
physiol...
 The occlusal forms-
• The form of the occlusal surfaces of artificial teeth,
wether of the Anatomic, Non anatomic or 0 d...
 Chewing efficiency-
• Results of early studies on chewing efficiency with
various occlusal forms were contradictory.
Tho...
 Denture base deformation –
• Studies done by Askew and Hoyer showed that
when the mandible with denture was pulled
into ...
 Tooth material –
• The material from which the denture teeth are made
may have some effect on the forces transmitted
thr...
CLASSIFICATION OF RESIDUAL
RIDGE
• The basic structural change in RRR is a
reduction in the size of the bony ridge under
t...
• In order to provide a simplified method for
categorizing the most common residual ridge
configurations, Atwood (1963) de...
• Several authors have affirmed the relationship of the
foramen to the inferior border of the mandible remains
relatively ...
GUIDED BY:
DR. MANESH LAHORI
PROFF & HEAD
DEPT. OF PROSTHODONTICS
KDDC, MATHURA
PRESENTED BY:
DR. PRATEEK AGRAWAL
M.D.S. I...
CONTENTS
• INTRODUCTION
• ETIOLOGY OF RIDGE RESORPTION
• CLASSIFICATION OF RESIDUAL RIDGE
• PREVENTION AND TREATMENT
• SUM...
TREATMENT AND PREVENTION
• SWENSON stated, “ The ideal ridge is one that is broad
in its bearing surface and has practical...
• The cause of the degenerative denture ridge
will determine the type of treatment.
• So a detailed examination must be pe...
• A comprehensive dental history including-
Previous prosthetic treatment
Number of old dentures made
Frequency of dent...
• Intra-oral examination should determine the
ridge form and extent of resorption. Mucosal
form on and surrounding the rid...
• The tongue size and tongue movements
should be assessed.
• Radiographs should also be taken which aids
in assessing ridg...
• A dietary analysis can be obtained through
several means.
• Their ability to chew will frequently dictate
their selectio...
I. Prevention:
– Best of all is to prevent the loss of teeth.
– Prevention and/or the correct diagnosis and
management of ...
– Diet is one of the most neglected facets of
treatment in degenerate denture ridge patients.
These patients need a diet h...
II. Prosthetic management:
A. IMPRESSION MAKING-
• In patients with severely resorbed ridges, lack of ideal
amount of supp...
• However, in resorbed ridge the extension of
the base is critical to avoid interferences with
the movement of border stru...
• Special techniques, to determine accurately
the denture border extension have been
evolved-
Fish recommended a techniqu...
Bernard Levin: Suggests making primary
impression with alginate (25% less water).
Special tray should be wider and heavie...
Winkler technique involves the use of the tissue
conditioning materials.
• A preliminary impression is made to obtain a
g...
• The borders are adjusted so that the lingual
flange and sublingual crescent area are in
harmony with the resting and act...
• From this point on, an open- or closed mouth
technique may be employed.
• In general, three applications of conditioning...
• The third and final wash is made with the relatively
light-bodied material.
• This results in an impression that has a t...
• It can be thought of as a mandibular denture
with minimal bony contact in the alveolar
ridge area, suspended in a compat...
Dynamic Impression Method:
• Its significance:
– Avoids the dislocating effect of the muscles on improperly
formed dentur...
Fabrication of the special tray is done.
A ridge of self curing resin is built up in the premolar molar region on each sid...
Sufficient amount of an irreversible hydrocolloid is mixed with 50%
extra water material and is placed directly into the m...
The patient should swallow three to four times at 10 seconds interval
while the final impression material is still in a mo...
In another method, an old denture can be used for a
dynamic impression when opposing natural or
artificial teeth are prese...
Klein in 1957, suggested three distinct types
of impression techniques for mandibular
dentures depending on the type of f...
– First Condition-
•When the mandibular ridge is almost
completely resorbed with just a rib of soft
fibrous tissue along t...
After a routine modeling compound wax
mandibular impression is made in the usual
manner, approximately 3mm of compound is
...
– Second Condition-
•In cases with almost complete resorption
and with a spiny ridge of dense bony tissue
along the crest ...
Compound impression is made as above. In
addition to the crest of ridge, compound is scraped
away along the crest of myloh...
–Third Condition-
• In cases where ridge is flat or concave.
The impression of lingual border is recorded
accurately with the impression wax.
This type of foundation should not requir...
B. SELECTION OF DENTURE BASE-
• For degenerative ridge patients there are
three types of denture bases:
– Methyl methacryl...
Methyl methacrylate resin denture bases:
• These are the standard bases normally used.
• These bases are quickly and easi...
Cast metal bases:
• Main advantage is the great accuracy of fit to the
tissues by surface tension, than acrylic denture
b...
• Advantages:
Prevention of acrylic warpage,
More strength,
Increased accuracy,
Less tissue change under the base,
Le...
Processed, Resilient, Lined Denture Bases
• Its greatest advantages are its cushioning
effect upon the mucosa and its abi...
• The lining is best when there is a 2 mm
thickness. So, it cannot be used in the cases
of small inter-ridge distance.
• T...
C. JAW RELATION-
• Correct recording of vertical and horizontal
relations are equally important for the
preservation of re...
• In horizontal relations unless centric relation is
established properly, the mandibular teeth will not
occlude properly ...
D. SELECTION OF TEETH AND OCCLUSION-
 Neutrocentric occlusion:
• The neutrocentric concept was developed by
DeVan.
• DeVa...
• The five elements of this scheme are:
• Position: the position of posterior teeth should be
centralized over the residua...
• Form: Flat teeth with no deflective inclines were
used so that there is no interference with
mandibular movements.
• Num...
 Linear occlusion:
• William H. Goddard introduced the concept
of linear occlusion.
• Frush described occlusion in geomet...
• Linear occlusion consists of the following basic
Parameters:
– Zero degree teeth (flat teeth) are opposed by bladed
(lin...
E. OVERDENTURES:
• Overdentures are designed to distribute the
masticatory load between the edentulous ridge and
the abutm...
• A comparison of immediate conventional
dentures and immediate overdentures found
half as much bone loss (0.9mm compared ...
F. SUBMERGENCE OF ROOTS (VITAL OR
NON-VITAL).
• Studies have shown that the roots that were
submerged remained asymptomati...
III. SURGICAL MANAGEMENT:
A. IMPLANTS-
• The various problems associated with RRR
and stability of removable soft tissue b...
• Advantages:
Maintenance of alveolar bone
Restoration & maintenance of occlusal vertical
dimension.
Maintain facial es...
Improved masticatory performance.
Immune to caries.
Increased trabeculation and density of bone.
Overall volume of bon...
B. VESTIBULAR EXTENSION PROCEDURE-
• Indicated when there is high muscular and
mucosal attachments.
• The reduction of alv...
C. RIDGE AUGMENTATION-
These are the procedures designed to
enlarge or increase the size, extent, or quality
of deformed r...
• Aims
– Restoration of optimum/near optimum ridge
height & width, ridge form, vestibular depth and
optimum denture bearin...
 Mandibular augmentation-
• Superior border augmentation
– Bone grafts
– Cartilage grafts
– Alloplastic grafts.
• Inferio...
Maxillary augmentation-
• Onlay bone grafting - autogenous /
allogenic grafts.
• Onlay grafting by alloplastic material.
...
SUMMARY
Residual ridge resorption is a chronic,
progressive, irreversible, and disabling disease ,
of multifactorial origi...
Although challenging, the severely
resorbed ridges can be resorted to a certain
level of mastication with the help of
impr...
As prosthodontists, we need to perform
the most meticulous and intelligent
prosthodontic care of the patient within our
ca...
BIBLIOGRAPHy
• Essentials of Complete Denture Prosthodontics, 2nd Edition, By Sheldon
Winkler
• Prosthodontic Treatment fo...
Resorbed ridge seminar koto
Resorbed ridge seminar koto
Resorbed ridge seminar koto
Upcoming SlideShare
Loading in …5
×

Resorbed ridge seminar koto

4,412 views

Published on

  • Hello! I have searched hard to find a reliable and best research paper writing service and finally i got a good option for my needs as ⇒ www.HelpWriting.net ⇐
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • You can hardly find a student who enjoys writing a college papers. Among all the other tasks they get assigned in college, writing essays is one of the most difficult assignments. Fortunately for students, there are many offers nowadays which help to make this process easier. The best service which can help you is ⇒ www.WritePaper.info ⇐
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • Free Shed Plans, 12000 SHED PLANS. FREE SHED PLANS CLICK HERE ▶▶▶ https://t.cn/A62YdXnY
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • Leptitox Upto 70% Off | $39 Only? ●●● https://t.cn/A6wnCpvk
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • Enough is a enough! Is this going to be the day you finally do something about your health? It is a lot easier than you think to be able to shed off unwanted weight. See how you can get started today with 1 minute weight loss routines! ▲▲▲ http://t.cn/A6PnIVD3
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here

Resorbed ridge seminar koto

  1. 1. GUIDED BY: DR. MANESH LAHORI PROFF & HEAD DEPT. OF PROSTHODONTICS KDDC, MATHURA PRESENTED BY: DR. PRATEEK AGRAWAL M.D.S. IIIrd YEAR
  2. 2. CONTENTS • INTRODUCTION • ETIOLOGY OF RIDGE RESORPTION • CLASSIFICATION OF RESIDUAL RIDGE • PREVENTION AND TREATMENT • SUMMARY • BIBLIOGRAPHY
  3. 3. 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. 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.
  4. 4. 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 phenomena has been described as Residual Ridge Resorption (RRR).
  5. 5. Residual ridge resorption after loss of teeth is a multifactorial oral problem. According to Atwood, the degree of mandibular loss of its alveolar portion is 3-4 times higher than alveolar resorption in the maxilla. The rate of RRR is different among persons and even at different sites in the same person.
  6. 6. Residual bone is considered to be the base which provides support for dentures and is an area where forces created while biting and chewing foods are transmitted. Loss of alveolar bone from the edentulous jaws is a serious and common clinical problem, especially among the elderly. In particular, “flat lower ridge” is associated with difficulties in providing successful dentures. Stability of lower denture in such cases is usually the distinguishing factor between success and failure.
  7. 7. ETIOLOGY OF RIDGE RESORPTION It is postulated that residual ridge resorption is a multifactorial, biomechanical disease that results from a combination of: • Anatomic factors • Metabolic factors • Mechanical factors • Prosthodontic factors
  8. 8. A. Anatomic factors:- Ridge resorption varies with-  Quantity and Quality of the bone.  Shape& Form of the ridges (Large, well-rounded ridges and broad palates would seem to be favorable anatomic factors)  Density of the ridge (density at any given moment does not signify the current, metabolic activity of the bone and bone can be resorbed by osteoclastic activity regardless of its degree of calcification)
  9. 9. B. 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.
  10. 10. • 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. • Ridge resorption varies directly with some systemic or localized bone resorptive factors and inversely with some bone formation factors.
  11. 11. • Some local biochemical factors in relation to periodontal disease which affects the ridge resorption- Endotoxins from dental plaque on unclear dentures. Osteoclast activating factor (OAF). Prostaglandins. Human gingival bone resorption stimulating factors. Heparin acts as a cofactor in bone resorption which is produced from mast cells
  12. 12. • Systemic factors influence the balance between the normal bone formation and bone resorption. These factors create a natural resistance to unfavorable local factors. They are-  Estrogen.  Thyroxin.  Growth hormone.  Androgens.  Calcium.  Phosphorus.  Vitamin D.  Protein.  Fluoride.
  13. 13. C. Mechanical factors:- Functional Factors- When force within physiologic limits is applied to bone that force brings about the remodeling of bone through a combination of bone resorption and formation • RRR directly proportional to Force:- – Amount, frequency, duration, direction, area over which force is distributed (force/unit area) and damping effect of the underlying tissue. – Some postulate that it is because of disuse atrophy and others as abuse of bone. – There is increased tendency for mandibular ridge to undergo resorption compared to maxilla.
  14. 14. Damping Effect/ Energy Absorption- Resorbing residual ridge is indirectly proportional to damping effect. Dampening effect takes place in the mucoperiosteum, which is a viscoelastic material. Maxillary bone (RR) is frequently broader, flatter and more cancellous than its mandibular counterpart. So it is ideally constructed for the absorption and dissipation of energy. Frost pointed out that the trabaculae in cancellous bone are arranged parallel to direction of compression deformation.
  15. 15. D. Prosthodontic factors:- Clinical observations indicate that excessive alveolar bone resorption can be caused by physiologically intolerable forces produced by functioning complete dentures. The inherent denture factors which may affect the supporting structures include: – The occlusal forms of the teeth. – The alignment of the denture teeth / occlusal pattern. – Deformation of the denture bases. – Materials with which denture teeth are made and – The effects of the loss of proper occlusal vertical dimension (over closure).
  16. 16.  The occlusal forms- • The form of the occlusal surfaces of artificial teeth, wether of the Anatomic, Non anatomic or 0 degree configuration, must have some effect on chewing efficiency and on forces tending to distort the denture bases. • One of the earliest opponents of the anatomic tooth form was French who coined the term “cusp trauma” as one of the most serious defects that had to be guarded against in complete denture construction. Soon after, Sear’s developed his non anatomic tooth form which initiated the introduction of many new designs to denture teeth throughout the years.
  17. 17.  Chewing efficiency- • Results of early studies on chewing efficiency with various occlusal forms were contradictory. Thompson, Trapozzon and Lazzari found anatomic teeth to be more efficient than non anatomic teeth, whereas Soboik, Manly and Vinton found no statistical difference between the efficiency of the anatomic and non-anatomic teeth. • More recent studies have shown that there is no statistical difference in the chewing performance in denture teeth with cuspal ranging from 0 to 30 degree.
  18. 18.  Denture base deformation – • Studies done by Askew and Hoyer showed that when the mandible with denture was pulled into lateral and protrusive more deformation was caused under the denture with anatomic tooth form than with non anatomic tooth form and same was with acrylic resin denture bases which resorbed the ridge more than the metal base when used with anatomic teeth than with non anatomic teeth.
  19. 19.  Tooth material – • The material from which the denture teeth are made may have some effect on the forces transmitted through the denture base material to the supporting ridges. • It is said that porcelain tooth when placed causes more resorption of ridge than acrylic tooth.  Loss of occlusal vertical dimension (over closure)- • The loss of proper occlusal vertical dimension after the insertion of complete dentures results in the triggering of a cyclic series of event detrimental to the health of the residual alveolar ridges.
  20. 20. CLASSIFICATION OF RESIDUAL RIDGE • 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.
  21. 21. • In order to provide a simplified method for categorizing the most common residual ridge configurations, Atwood (1963) described a system of six orders of residual ridge-  Order I – Pre extraction.  Order II – Post extraction.  Order III – High well rounded.  Order IV – Knife edge.  Order V – Low, well rounded.  Order VII – Depressed.
  22. 22. • Several authors have affirmed the relationship of the foramen to the inferior border of the mandible remains relatively constant in spite of increasing age or resorption of the alveolar process above the foramen. (JPD; 32 (1); 1974; 7-12) – CLASS I: Up to one third of the original vertical height lost. – CLASS II: From one third to two thirds of the vertical height resorbed. – CLASS III : Two thirds or more of the mandibular height lost.
  23. 23. GUIDED BY: DR. MANESH LAHORI PROFF & HEAD DEPT. OF PROSTHODONTICS KDDC, MATHURA PRESENTED BY: DR. PRATEEK AGRAWAL M.D.S. IIIrd YEAR
  24. 24. CONTENTS • INTRODUCTION • ETIOLOGY OF RIDGE RESORPTION • CLASSIFICATION OF RESIDUAL RIDGE • PREVENTION AND TREATMENT • SUMMARY • BIBLIOGRAPHY
  25. 25. TREATMENT AND PREVENTION • SWENSON stated, “ The ideal ridge is one that is broad in its bearing surface and has practically parallel sides.” • But in the degenerative denture ridges- 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.
  26. 26. • The cause of the degenerative denture ridge will determine the type of treatment. • So a detailed examination must be performed. • Complete mouth and panographic radiographs are essential.
  27. 27. • A comprehensive dental history including- Previous prosthetic treatment Number of old dentures made Frequency of denture rebasing should be appreciated in order to estimate both the apparent rate of progression of RRR and the capability of the individual to cope up with previous denture.
  28. 28. • Intra-oral examination should determine the ridge form and extent of resorption. Mucosal form on and surrounding the ridge should be checked along with palpation to locate any tender areas of mucosa. • The assessment of quantity, quality, viscosity of the saliva should be made. This may affect physical retention of the denture associated with the cohesive and adhesive properties of saliva between the denture and mucosa.
  29. 29. • The tongue size and tongue movements should be assessed. • Radiographs should also be taken which aids in assessing ridge resorption, inadequate bone thickness (risk of spontaneous fracture). The position of the mental nerve and mandibular canal can also be established. • Diagnostic models may also be taken to allow case evaluation in the absence of the patient.
  30. 30. • A dietary analysis can be obtained through several means. • Their ability to chew will frequently dictate their selection of food, and this will usually generate a diet high in refined carbohydrates and low in proteins, vitamins and minerals- just the opposite of what is needed to help stop the onslaught of bone destruction.
  31. 31. I. Prevention: – Best of all is to prevent the loss of teeth. – Prevention and/or the correct diagnosis and management of all of the etiologic factors of the disease. – Any systemic illness that is contributing to the degenerated bone condition must be corrected or stabilized. 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.
  32. 32. – Diet is one of the most neglected facets of treatment in degenerate denture ridge patients. These patients need a diet high in protein, vitamin, and mineral content. So the dietary problems should be corrected. – Correcting deficiency of various hormone, vitamin, mineral etc. – Tissue treatment therapy to rejuvenate the tissue bearing area by the use of soft conditioning material. – Muscle strengthening exercises.
  33. 33. II. Prosthetic management: A. IMPRESSION MAKING- • 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. A broad area coverage with maximal denture base extension decreases the force experienced per unit area of the mucosa beneath the denture and the likelihood of its trauma.
  34. 34. • However, in resorbed ridge the extension of the base is critical to avoid interferences with the movement of border structure. • There are different impression techniques to follow. The principles employed in impression making should be maximal support, retention and stability.
  35. 35. • Special techniques, to determine accurately the denture border extension have been evolved- Fish recommended a technique where, sublingual fold space, extending from premolar to premolar region on each side was recorded. This horizontal flange acted as ‘tongue rest’ thereby increasing the stability and support.
  36. 36. Bernard Levin: Suggests making primary impression with alginate (25% less water). Special tray should be wider and heavier in the buccal shelf area. While border molding tongue should be allowed to extend fully. Patient should make only moderate movements. Final impression should be completed with Elastomeric impression material. Exaggerated tongue movements should be made.
  37. 37. Winkler technique involves the use of the tissue conditioning materials. • A preliminary impression is made to obtain a generally overextended registration. • Using the resulting cast, a resin tray is made, and an occlusal wax rim is added to simulate the height and position of the anterior and posterior teeth and then tried in the mouth.
  38. 38. • The borders are adjusted so that the lingual flange and sublingual crescent area are in harmony with the resting and active phases of the floor of the mouth. • The buccal and labial extension of the acrylic tray is adjusted to be deliberately short of the reflections of the cheek and lip. • A stable, nonretentive tray should now be available.
  39. 39. • From this point on, an open- or closed mouth technique may be employed. • In general, three applications of conditioning material are used. • Two applications of the more viscous material are made, each application being allowed to remain in the mouth for eight to ten minutes, removed, rinsed, and checked. • Pressure areas are corrected at the time of the first application.
  40. 40. • The third and final wash is made with the relatively light-bodied material. • This results in an impression that has a tissue-placing effect, very thick and conforming buccal borders, and a relatively thick lingual and sublingual crescent area. • The overall denture is bulkier, with more surface contact area, than is found in the conventional denture.
  41. 41. • It can be thought of as a mandibular denture with minimal bony contact in the alveolar ridge area, suspended in a compatible soft tissue hammock. • This method results in improved retention of the mandibular denture, even with its built-in instability, because of the conformity of the residual alveolar ridge.
  42. 42. Dynamic Impression Method: • Its significance: – Avoids the dislocating effect of the muscles on improperly formed denture border. – Complete utilization of the possibilities of active and passive tissue fixation of the denture. – Dynamic impressions in contrast to non dynamic impression records the tissues in an immobile condition, and – Semi dynamic impressions in which the denture borders are determined by partly passive and partly active movements was described by Fournet and Tull.
  43. 43. Fabrication of the special tray is done. A ridge of self curing resin is built up in the premolar molar region on each side to support the thermoplastic material. While the thermoplastic material is soft the tray is placed in position on the lower ridge in the mouth and the patient is asked to close the jaws slowly. The upper residual ridge will form an impression in the soft thermoplastic material at a height corresponding to the rest mandible. Tray is removed from mouth and cooled. Lingually the mandibular rests should be concave to provide space for the tongue.
  44. 44. Sufficient amount of an irreversible hydrocolloid is mixed with 50% extra water material and is placed directly into the mouth to cover all tissues . The tray is pressed through alginate by digital force until the stops are firmly seated on the residual ridge. Then, the patient is asked to close his mouth slowly until the mandibular rests have obtained firm contact with the maxillae.
  45. 45. The patient should swallow three to four times at 10 seconds interval while the final impression material is still in a moldable condition. The action of the muscles that function in deglutition is accentuated because the mandibular rests prevent the mandible from reaching the vertical, relation of occlusion and force it to remain in its rest position. This procedure develops a registration of the denture space which ordinarily results in a proper extension of the lingual flanges of the finished dentures. Forceful protrusion of the lips brings the mentalis and orbicularis oris muscles into action and is responsible for forming the labial part of the impression.
  46. 46. In another method, an old denture can be used for a dynamic impression when opposing natural or artificial teeth are present. Often the vertical dimension at occlusion is decreased hence steps are placed at re-established height. The mandibular rests are built up include the inter-occlusal distance. In still another method, denture is processed in a conventional manner. Then a correcting dynamic impression is made in the denture base to reshape and complete the final design and the denture is relined. This procedure was originally indicated by Momme in 1872.
  47. 47. Klein in 1957, suggested three distinct types of impression techniques for mandibular dentures depending on the type of foundation. (J. Pros. Dent. September, 1957)
  48. 48. – First Condition- •When the mandibular ridge is almost completely resorbed with just a rib of soft fibrous tissue along the crest. This rib of tissue is easily displaced and can be a constant source of irritation, if the impression is not recorded correctly.
  49. 49. After a routine modeling compound wax mandibular impression is made in the usual manner, approximately 3mm of compound is relieved over the crest of the ridge and a cast is poured. The clear acrylic resin tray processed on the preliminary cast will not contact the ridge crest. Three holes are drilled in the tray on each side in the areas of the ridge crest to prevent a building up of undesired pressure. The final impression is made inside the tray and the free flowing paste will allow the soft tissue along the crest of the ridge to place itself.
  50. 50. – Second Condition- •In cases with almost complete resorption and with a spiny ridge of dense bony tissue along the crest of the residual ridge.
  51. 51. Compound impression is made as above. In addition to the crest of ridge, compound is scraped away along the crest of mylohyoid ridge and posterior lingual flange to a depth of 2mm. Physiologic wax is added and primary impression completed. The cast is poured and the area of the mylohyoid ridge is relieved with 0.001 inch tin foil. The clear acrylic resin tray is made and final wash impression made. Master cast is poured. The knife edged ridge crest is again relieved with 0.001 inch tin foil. Thus forces of mastication will be exerted along the sides of the ridge rather than on the crest.
  52. 52. –Third Condition- • In cases where ridge is flat or concave.
  53. 53. The impression of lingual border is recorded accurately with the impression wax. This type of foundation should not require any alteration or modification in the impression technique, except where the mylohyoid ridge becomes a disturbing factor. This situation is handled as described previously. The coverage of the denture-bearing area will be the same as for an average foundation. The supporting structures have changed, but the muscles of the border regions still function normally and will mold the borders of the impression. The technique is same as stated above.
  54. 54. B. 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
  55. 55. 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.
  56. 56. 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 aluminum.
  57. 57. • Advantages: Prevention of acrylic warpage, More strength, Increased accuracy, Less tissue change under the base, Less porosity and therefore easier to clean and keep clean, Thermal conductivity, Less deformation in function.
  58. 58. 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 indicated in the cases of – Severely undercut ridges where surgery is contraindicated – Patients with no ridge – Patients with a flat ridge and delicate tissues. – Spinous ridge, tori, the mental foramen, and the genial tubercles
  59. 59. • The lining is best when there is a 2 mm thickness. So, it cannot be used in the cases of small inter-ridge distance. • The biggest disadvantage is deterioration of the resilient liner in few months.
  60. 60. C. JAW RELATION- • Correct recording of vertical and horizontal relations are equally important for the preservation of residual bone resorption. • The difficulty in obtaining good jaw-relation records is complicated by the frequently impaired masticatory apparatus. • Perhaps the most important factor in articulation is that centric occlusion be harmonious with the centric relation.
  61. 61. • In horizontal relations unless centric relation is established properly, the mandibular teeth will not occlude properly with those on the maxillary arch, thus proper occlusion is essential to the health of bony support. • Otherwise during eccentric movement it causes pressure on bone due to failure of the stability factor. Hence cause resorption of bone.
  62. 62. D. SELECTION OF TEETH AND OCCLUSION-  Neutrocentric occlusion: • The neutrocentric concept was developed by DeVan. • DeVan has suggested embodying the two key objectives of his occlusal scheme – Neutralization of inclines, – Centralization of forces. • The neutralization of inclines and centralization of occlusal forces aids in stability without interfering with speech, appearance and chewing capacity.
  63. 63. • The five elements of this scheme are: • Position: the position of posterior teeth should be centralized over the residual ridge so that the forces are perpendicular to the support areas. This avoids tensile and shearing forces. • Proportion: DeVan reduced the teeth width by 40%. This reduced the vertical stress on the ridge. Horizontal forces are reduced because friction between opposing surfaces is decreased. The forces are thus centralized without encroaching on the tongue. • Pitch: This is the inclination or tilt of the occlusal plane. It is oriented parallel to the underlying ridge and midway between them. This directs the forces perpendicular to the mean osseous foundation plane.
  64. 64. • Form: Flat teeth with no deflective inclines were used so that there is no interference with mandibular movements. • Number: The number of posterior teeth was reduced from eight to six. This reduced the magnitude of occlusal force and centralized it to second premolar and first molar.
  65. 65.  Linear occlusion: • William H. Goddard introduced the concept of linear occlusion. • Frush described occlusion in geometric terms as one dimensional (linear), two dimensional (flat) and three dimensional (cusped). • Groans and Stout explained how anatomic and non anatomic occlusal schemes transmit lateral forces to the denture and reduce stability and suggested that the linear occlusal scheme has the potential for creating the smallest lateral force component.
  66. 66. • Linear occlusion consists of the following basic Parameters: – Zero degree teeth (flat teeth) are opposed by bladed (line contact) teeth in which the blade is a straight line over the crest of the ridge. – The arch which requires the greatest stability receives the bladed teeth (the mandible most often requires greater stability and receives bladed teeth). – There is no anterior interference to protrusive or lateral movements. – This non-interceptive occlusion provides a consistent vertical seating force in both centric and eccentric; hence transverse vectors are eliminated.
  67. 67. E. OVERDENTURES: • Overdentures are designed to distribute the masticatory load between the edentulous ridge and the abutments. • The overdenture transfers occlusal forces to the alveolar bone through the periodontal ligament of the retained tooth roots. • Proprioceptive feedback, from the periodontal ligament to the muscles of mastication, may act to prevent occlusal overload and thereby prevent bone resorption because of excessive forces. • The short term and long-term preservation of alveolar bone has been documented not only adjacent to the overdenture abutments but also adjacent to the edentulous ridges.
  68. 68. • A comparison of immediate conventional dentures and immediate overdentures found half as much bone loss (0.9mm compared with 1.8 mm) in the anterior mandible over the first year in the overdenture group, surprisingly, the bone loss was also slowed in the posterior mandible. • The increased stability that resulted from the use of overdentures may limit lateral forces placed on residual bone.
  69. 69. F. SUBMERGENCE OF ROOTS (VITAL OR NON-VITAL). • Studies have shown that the roots that were submerged remained asymptomatic and help to preserve residual ridge and it may be an alternate method to conventional over denture.
  70. 70. III. SURGICAL MANAGEMENT: A. IMPLANTS- • 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.
  71. 71. • Advantages: Maintenance of alveolar bone Restoration & maintenance of occlusal vertical dimension. Maintain facial esthetics. Improved phonetics Improved occlusion Improved psychological health. Regained proprioception. Increased stability, retention
  72. 72. Improved masticatory performance. 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.
  73. 73. B. VESTIBULAR EXTENSION PROCEDURE- • Indicated when there is high muscular and mucosal attachments. • The reduction of alveolar ridge size is frequently accompanied by an apparent encroachment of muscle attachments on the crest of the ridge. These serve to reduce the available denture bearing area and undermine denture stability. • Soft tissue vestibuloplasties including localized mucosal flap to a full-skin graft vestibuloplasty may be performed to increases the relative height and extent of the denture foundation.
  74. 74. C. RIDGE AUGMENTATION- These are the procedures designed to enlarge or increase the size, extent, or quality of deformed residual ridge.
  75. 75. • Aims – Restoration of optimum/near optimum ridge height & width, ridge form, vestibular depth and optimum denture bearing area – Protection of neurovascular bundle – Establishment of proper inter arch relationship – Improvement of retention and stability of denture – Improve the patient comfort for wearing the denture.
  76. 76.  Mandibular augmentation- • Superior border augmentation – Bone grafts – Cartilage grafts – Alloplastic grafts. • Inferior border augmentation – Bone grafts (autogenous or allogenic freeze dried cadaveric mandible) – Cartilage grafts. • Interpositional or Sandwitch bone grafts – Bone grafts – Cartilage grafts – Hydroxyapatite blocks.
  77. 77. Maxillary augmentation- • Onlay bone grafting - autogenous / allogenic grafts. • Onlay grafting by alloplastic material. • Interpositional or Sandwich grafts. • Sinus lift procedure.
  78. 78. 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. Resorbed ridge 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.
  79. 79. Although challenging, the severely resorbed ridges can be resorted to a certain level of mastication with the help of improved impression techniques, proper selection of occlusion schemes, the use of specialized dentures techniques and a regular follow up. More recently, implant supported overdentures are playing tremendous role in the treatment of the severely resorbed ridges.
  80. 80. As prosthodontists, we need to perform the most meticulous and intelligent prosthodontic care of the patient within our capabilities for the restoration of the physical and mental vitality of the patient. …and then , it would not seem a nebulous hope that some day there will be control over residual ridge resorption.
  81. 81. BIBLIOGRAPHy • Essentials of Complete Denture Prosthodontics, 2nd Edition, By Sheldon Winkler • Prosthodontic Treatment for Edentulous patients, 11th Edition, By Boucher. • Impression for Complete Denture, by Bernard Levin • Misch implant dentistry • The management of gross alveolar resorption : (JPD 1973, vol. 29, Pg. 397). • The degenerative denture ridge-Care and treatment. (JPD 1974, vol. 32, 477-492). • Reduction of residual ridges: A maior oral disease entity (JPD 1971, vol. 26, 266-279). • Lamie G.A. : The reduction of the edentulous ridge. J. Prosthet. Dent. 10 : 605-611, 1960. • Conservative prosthodontic procedures to improve mandibular denture stability in an atrophic mandibular ridge. JIPS December 2008, Vol 8, Issue 4.

×