PROSTHODONTIC MANAGEMENT OF RESIDUAL RIDGE REDUCTION

Residual ridge resorption is progressive and irreversible loss of alveolar ridges which makes the fabrication of dentures challenging to dentists

1. DR SANKAR MADHAVAN

3.  
Alveolar bone – Bony portion of the maxilla or
the mandible in which roots of the teeth were
held by the fibers of the periodontal ligament.
 
Residual alveolar ridge – portion of the alveolar
ridge and its soft tissue covering which remains
following the removal or loss of teeth.
 
Residual ridge resorption – A term used for the
diminishing quantity and quality of the residual
ridge after teeth are removed.

5. •After tooth extraction, a 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.

6. •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)
•The rate of RRR is different among persons and even
at different sites in the same person.

10. Clinically easy to visualize the ridge
form however palpation is must
The basic structural change in RRR is a
reduction in the size of the bony ridge under
the mucoperiosteum.

16. Based on the clinical fact :
RRR is inevitable
 Its rate varies
 The rate of resorption is greater than the rate
of formation in some patients
….RRR should be considered a pathologic
process.

17. 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
Varying degrees of inflammatory cells including
lymphocytes and plasma cells, have also been seen.

18. Pathophysiology of
residual ridge resorption

19. It is a normal function of bone to undergo constant remodeling
throughout life through the process of bone resorption and bone
formation.
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. RRR is chronic, progressive, irreversible and
cumulative.

21. PATHOGENESIS
Usual life of RRR-Extraction-sharpedges-
rounded-resorbbuccolingually-knife edged-
resorb-depressed
In studies the mean ratio of anterior maxillary
to anterior mandibular RRR was 1:4(Tallegren,
Atwood andCoz)

23.  
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.
 
 Thus the maxillary residual ridge looses height
and maxillary arch becomes narrower from side to
side and shorter anteroposteriorly.

25. 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.
 

28. To date, it appears that RRR is world-wide, occurs
in males and females, young and old, 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

32.  
RRR α Bone resorption factors
Bone formation
factors
 
Local bone resorbing factors
include
◦Endotoxins from dental plaque
◦Osteoclast activating factor
◦Prostaglandins
◦Human gingival bone resorption stimulating
factor
◦Heparin

33. Systemic factors
1. Bone loss due to increased resorption :
Hypophosphatemia
  High parathyroid hormone
2 .Bone loss due to decreased formation 
Excess amount of glucocorticoid hormones which
inhibit bone formation .
 3. Bone loss due to unknown causes
Age related bone loss :
Decreased physical activity
Decreased estrogen secretion after about 40 yrs

35. FORCE
Depends on the amount,frequency,duration ,
force/area…
DAMPING EFFECT
Viscoelastic property of the mucoperiosteum-Energy
absorption.
cancellous bone has increased damping effect
TIME

39. Methods of evaluation of bone loss in RRR
•Radiographs:
- Cephalometrics .
- Panoramic
- CT.
•MRI
•Tetracycline labeling
•Mercury porosimetry
•Anatomic studies

40. Management
of
residual ridge resorption

43. Selective pressure impression
Tissue conditioner
Neutral zone technique
Balanced occlusion
Well contoured flanges and denture base

48. Summary

49. 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.

50. THANK
YOU