A brief outline on what to study for residual ridge resorption.

2. Residual Ridge
Resorption

3. Contents
Introduction
◦ Bone remodelling
Definition
Consequences
Classifications
Epidemiology
Pathology
◦ Gross
◦ Microscopic
Pathophysiology
Pathogenesis
Etiology
Evaluation
Treatment and prevention
Conclusion

4. Introduction
o Structural elements of bone
o Physiology of bone remodeling
oIn Maxilla and mandible,

6. Definition
A term used for the diminishing quantity and quality of the residual
ridge after teeth are removed.

7. Consequences
Height of ridge decreases causing –
muscle attachments closer to the crest of the residual ridge
alteration in position of mandibular canal, mental foramen, genial tubercles, nasopalatine foramen
loss of sulcus width and depth
ridge relationship changes
inter-arch space increases
flabby ridge
Anterior rotation of the mandible.
Vertical dimension of lower third of face decreases.
Esthetic problems.

8. Atwood classified residual ridge resorption into:
Order 1: pre-extraction
Order 2: post-extraction
Order 3: high, well-rounded
Order 4: knife-edged
Order 5: low, well rounded
Order 6: depressed
Classifications
LEKHOLM AND ZARB CLASSIFICATION
A. Virtually intact alveolar bone.
B. Minor resorption of alveolar ridge.
C. Advanced resorption of alveolar ridge to
base of dental arch.
D. Intial resorption of base of dental arch.
E. Extreme resorption of base of dental
arch.

9. To date it would appear that RRR is worldwide, occurs in males and females, young and old, in
sickness and in health, with an without dentures, and is unrelated to the primary reason for the
extraction of the teeth (caries or periodontal disease).
Epidemiology

10. Pathology – Gross
Studies on dried jaw bones from cadavers and lateral cephalograms have shown –
◦ Reduction of bone size – Atwood’s classification.
◦ Redundant or inflamed soft tissues.
◦ Excessive and redundant mucoperiosteum.
◦ Exposure of medullary bone on crest.
◦ Exposure of mandibular canal.
◦ RRR does not stop with the alveolar process.
◦ Complete resorption of bone not seen.

11. Microscopic studies have shown -
◦ Osteoclastic activity on the external surface of the crest of residual ridges
◦ Wide variation in the configuration, density and porosity of the residual ridges, sometimes
even with evidence of osteoporosis.
◦ Varying degrees of inflammatory cells are found in areas that appear from clinically normal to
frankly inflamed in edentulous patients or who were denture or non-denture wearers.
◦ Presence of new bone and reversal lines inside the residual ridge and minute areas of bony
repair.
◦ Mucoperiosteum showed varying degrees of keratinization, acanthosis, edema and
architectural pattern of mucosal epithelium.
Pathology - Microscopic

12. Pathophysiology
Bone remodeling
◦ Bone formation = Bone resorption (normal health)
◦ Bone formation > Bone Resorption (growth period)
◦ Bone formation < Bone Resorption (Osteoporosis, periodontal disease when teeth present)
◦ Bone formation < Bone Resorption (RRR after teeth extraction)
a b c
 IS RESIDUAL RIDGE RESORPTION A PHYSIOLOGIC PROCESS OR A PATHOLOGIC ONE?????

13. Pathogenesis
Pre Extraction (order I)
extraction
Post extraction(order II)
sharp edges-rounded-
osteoclastic resorption-leaves
High well rounded(order III)
resorption-cont-lab to ling
ridge-narrow-gives
knife edged(order IV)
Cont-shorter&even eventually
disapp-leaves
Low well rounded(order v)
Eventually-resorbs-leaves
Depressed ridge(order IV)

14. Residual Ridge Resorption is a multifactorial, biomechanical disease that results from a
combination of anatomic, metabolic, and mechanical determinants.
Etiology

15. ANATOMIC FACTORS
Residual Ridge Resorption varies with the quantity and quality of the bone of the residual ridge.
Residual Ridge Resorption  Anatomic factors
Etiology

16. METABOLIC FACTORS
RRR varies directly with certain systemic or localized bone resorptive factors and
inversely with certain systemic or localized bone formation factors.
RRR  Bone resorption factors
Bone formation factors
Systemic :
 Bone loss due to decreased formation.
 Bone loss due to increased resorption.
 Bone loss due to unknown causes.
 Osteoporosis
Local:
 Endotoxins – from dental plaque.
 Osteoclasts activating factors (OAF)
 Prostaglandins.
 Human gingival bone resorption stimulating factor.
 Heparin – co-factor in bone resorption secreted by mast cells.
 Others include -Trauma (especially under ill-fitting denture), which leads to increased or decreased vascularity and
changes in oxygen tension
Etiology

17. Etiology
MECHANICAL FACTORS
Residual Ridge Resorption varies forces exerted on the bone and the damping effect caused by
the tissues covering the bone.
Residual Ridge Resorption  Force
Residual Ridge Resorption  1
Damping effect

18. Etiology
In addition to the three major categories of factors (anatomic, metabolic, and mechanical), the
importance of the time since extraction to the bone-loss has to be considered.
BONE LOSS (in mm) rate of RRR  1
Time
TIME (19 years)

19. Etiology
PROSTHETIC FACTORS
The denture factors which may affect the supporting structures are :
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.
Effects of loss proper occlusal vertical dimensions. (overclosure)

20. Evaluation
Radiographs:
- Cephalometric
- Panoramic
Tetracycline labeling
Mercury porosimetry

21. Treatment and Prevention
Systemic evaluation
Diet
Treatment of tissues causing RRR
Pre prosthetic surgery
Prosthetic management
-Impression techniques.
-Denture base selection.
-Teeth selection and arrangement.
-Overdenture fabrication
-Implant supported prosthesis.

22. Conclusion

23. Any doubts?????