This document discusses residual ridge resorption, which is the ongoing breakdown of the jawbone after tooth loss. It defines residual ridge resorption and classifies the types and stages. Factors that influence the rate and amount of resorption include anatomy, mechanics, metabolism, prevention through nutrition and implant placement. Surgical techniques like ridge augmentation and metal dentures can treat severe resorption. The conclusion emphasizes educating patients on treatment options based on their individual prognosis.

2.  Definitions
 Pathology
 classification
 Pathogenesis
 Epidemiology
 Etiology
 Prevention
 Treatment
 Conclusion

3. Residual alveolar ridge is the portion of the alveolar ridge
and its soft tissue covering which remains following the
removal of or loss of teeth.
[GPT-8]
INTRODUCTION

4. • The residual bony architecture of the maxilla
and mandible undergoes a life-long catabolic
remodeling.
• The rate of reduction in size of the residual ridge is
maximum in the first 3-6 months and then
gradually tapers off.
• However, bone resorption activity continues
throughout life at a slower rate, resulting in loss
of varying amount of jaw structure, ultimately
leaving the patient a ‘dental cripple’.

5. CLASSIFICATION

6. CLASSIFICATION BY ATWOOD’S
• 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
Pre extraction Post ext High, well rounded
Knife edge Low well rounded Depressed

8. • Immediately following the extraction (Order II),
any sharp edges remaining are rounded off by
external osteoclastic resorption leaving a high well
rounded ridge (Order III).
• As resorption continues from the labial and lingual
aspects, the crest of the ridge becomes increasingly
narrow, ultimately becoming knife edged (Order IV).
• As the process continues, the knife-edge becomes
shorter and eventually disappears leaving a low well-
rounded or flat ridge (Order V). Eventually this too
resorbs, leaving a depressed ridge (Order VI).

9. • Class I : Upto one third of the original
vertical height lost.
• Class II : From one third to two thirds of the
vertical height lost.
• Class III : Two third or more of the
mandibular height lost.
CLASSIFICATION BY WICAL AND SWOOPE

10. ACCORDING TO THE AMERICAN
COLLEGE OF PROSTHODONTISTS
Based on Bone Height (Mandible only)
• Type I: Residual bone height of 21 mm or greater
measured at the least vertical height of the mandible
• Type II: Residual bone height of 16 - 20 mm
measured at least vertical height of the mandible.
• Type III: Residual alveolar bone height of 1 1 - 1 5
mm measured at the least vertical height of the
mandible.
• Type IV : Residual vertical bone height of 10 mm or
less measured at the least vertical height of the
mandible.

11. PATHOGENESIS

12. • The pathogenesis of residual ridge resorption is not
well understood.
• Longitudinal studies of the form and weight of the
edentulous residual ridge in wearers of complete
dentures have demonstrated a continuous loss of
bone tissue after tooth extraction and placement of
complete dentures.
• The reduction is a sequel of alveolar remodelling due
to altered functional stimulus of the bone tissue. It
follows a chronic progressive and irreversible course
that often results in severe impairment of prosthetic
restoration and oral function.

14. • Epithelial tissues begin its proliferation and migration
within the first week and the disrupted tissue integrity
is quickly restored.
• Histologic evidence of active bone formation is seen as
early as 2 weeks after the extraction and the socket is
progressively filled with newly formed bone in about 6
months..
• The most striking feature of the extraction wound
healing is that even after the healing of wounds, the
residual ridge undergoes a lifelong catabolic
remodeling.

15. • This unique phenomenon 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.

16. According to Boucher,
 During the first year after tooth extraction, the
reduction in residual ridge height in the
midsagittal plane is
 2-3 mm for maxilla
4-5 mm for mandible
 Annual rate of reduction in height
0.1-0.2 mm for mandible
4 times less in the maxilla
AMOUNT AND RATE OF BONE
RESORPTION

17. • Maxilla resorbs upward and inward
to become progressively smaller
because of the direction and
inclination of the roots of the
teeth and the alveolar process.
• The opposite is true of the
mandible, which inclines outward and
becomes progressively wider.
• This progressive change of the
edentulous mandible and
maxilla makes many patients
appear prognathic.
DIRECTION OF BONE RESORPTION

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

19. • In the Mandible, large proportions of bone
loss occurs in the
 labial side of anterior residual ridge,
 equally on the buccal and lingual side in premolar
region and
 lingually in the posterior or molar region.
• In the Maxilla bone loss primarily occurs on the
labial or buccal aspect.
PATTERNS OF BONE
RESORPTION

20. • While teeth arrangement we should try to restore
the natural position of the teeth before they were
lost, Hence teeth in the maxillary arch are
arranged slightly labially and buccally.
• While in the mandible, teeth in the anterior
region are arranged labially, on the centre of the
ridge in the premolar region and slightly
lingually in the molar region.

21. EPIDEMIOLOGY OF RESIDUAL
RIDGE RESORPTION
• To date, it appears that RRR 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).

22. AETIOLOGY

23. • RRR is a multifactorial
biomechanical disease
caused by a
combination of
◦ ANATOMIC FACTORS
◦ MECHANICAL
FACTORS
◦ METABOLIC
FACTORS
AETIOLOGY OF RESIDUAL
RIDGE RESORPTION

24. • It is postulated that RRR varies with the
quantity and quality of the bone of residual
ridges.
RRR α Anatomic factors
ie, the more bone there is, the more
RRR will ultimately be.
But this cannot be considered a good prognostic
factor, because in some cases large ridges resorb
rapidly and some knife-edge ridges may remain
with little change for long periods of time.
ANATOMIC FACTORS

25. ANATOMIC FACTORS
 These are more pronounced in mandible with the
maxilla; associated more in patients with short and
square with increased masticatory forces.
 Large well-rounded ridges and broad palates are
favourable anatomic factors for residual ridge
resorption.

26. ANATOMIC FACTORS
 Alveoplasty
 But this cannot be considered a good prognostic
factor, because in some cases large ridges resorb
rapidly and some knife-edge ridges may remain with
little change for long periods of time.

27. • RRR varies directly with certain systemic or
localized bone resorptive factors and
inversely with certain bone formation
factors.
RRR  BONE RESORPTION FACTORS
BONE FORMATION FACTORS
METABOLIC FACTORS

28. BONE RESORPTION FACTORS
• Correct amount of
circulating estrogen,
thyroxine, growth hormone,
calcium, phosphorus,
• vitamin D ,
• Osteoporosis
• Hypophosphetemia
• Parathormone
• Calcitonin
LOCAL SYSTEMIC
• Endotoxins from dental plaque
• Osteoclast activating
factor(OAF)
• Prostaglandins
• Human gingival bone
resorption factor
• Trauma due to ill fitting
dentures which leads to
increased or decreased
vascularity and changes in
oxygen tension.

29. Osteoporosis is defined by the WHO as bone mineral
density (BMD) greater than 2.5 standard deviations
below that of the young adult BMD.
Osteoporosis is common in aging individuals,
especially in post menopausal women when the
estrogenic blood level is low.
In elderly men and women, osteoporosis is caused
by a variety of factors such as calcium loss,
calcium deficiency, hormonal deficiency, change in
protein nutrition and decreased physical activity.
OSTEOPOROSIS

30. Normal Bone Osteoporosis

31. Residual ridge resorption of the jaws is also more
rapid in increasing age group, depleted bone being
prone to the injurious impact of mechanical forces.

32. MECHANICAL FACTORS
 Though residual ridge resorption may be inevitable
due to ‘disuse atrophy’, it can also be caused due to
excessive force transmitted through denture wearing
and unstable occlusal conditions.

33. MECHANICAL FACTORS
 The mechanical factors (masticatory factors or
parafunctional forces) transmitted by the denture or
the tongue to the residual ridge are assumed to be
important factors in the remodelling process.
However, there is no scientific evidence that
parafunctional forces are related to the degree of
residual ridge reduction.

34. • Apparent loss of sulcus width and
depth.
• Displacement of muscle attachment
close to the ridge.
• Loss of vertical dimension of
occlusion.
• Reduction of the lower face height.
• Anterior rotation of
mandible and increase in
relative prognathism.
CONSEQUENCES OF RESIDUAL
RIDGE RESORPTION

35. CONSEQUENCES OF RESIDUAL
RIDGE RESORPTION
• Mental foramen may come to lie at or near the level of
upper border of the body of mandible.
• The genial tubercles project above the upper border of
the mandible in the symphysial region.
• Flattening of the vault of the palate.

36. CONSEQUENCES OF RESIDUAL
RIDGE RESORPTION
• Reduction in the height of both the maxillary and
mandibular edentulous arches. While the maxillary
arch resorbs buccally and labially with a concomitant
reduction in perimeter or circumference of the arch,
the mandibular arch resorbs in a labial and lingual
direction resulting in widening of the arch posteriorly.
This will lead to the confinement of maxillary arch
within the mandibular arch in long-standing
edentulous situations, giving a pseudo class III ridge
relationship.

37. CONSEQUENCES OF RESIDUAL
RIDGE RESORPTION
• Changes in inter alveolar relationship after
progression of the residual ridge reduction, which is
essentially centripetal in the maxilla and centrifugal in
the mandible.
• Morphological changes of the alveolar bone such as
sharp, spiny uneven residual ridges.
• Location of mental foramina close to the ridge crest.

38. PREVENTION OF RESIDUAL
RIDGE RESORPTION
a. Prevention of loss of natural teeth:
• Alveolar bone supporting natural teeth receives
tensile loads through a large area of periodontal
ligament.
• While the edentulous residual ridge receives
vertical, diagonal and horizontal loads applied by
a denture with a surface area much smaller than
the total area of the periodontal ligament of all
the natural teeth that had been present.

39. Optimal tissue health prior to making impression.
Impression procedures
• Minimal pressure impression technique.
• Selective pressure impression technique:
places stress on those areas that best resist
functional forces
• Adequate relief of non stress bearing areas
eg. Crest of mandibular ridge.

40. • Avoidance of inclined planes to minimize
dislodgment of dentures and shear forces.
• Centralization of occlusal contacts to increase
stability and maximize compressive forces.
• Provision of adequate tongue room to improve
stability of denture in speech and mastication.

41. • Adequate interocclusal distance during jaw rest
to decrease the frequency and duration of tooth
contact.
• Occlusal table should be narrow
• The concept and arrangement of teeth in
neutral zone helps the teeth to occupy a space
determined by the functional balance of the
oro- facial and tongue musculature.

42. • It has been seen that one of the cofactor in RRR
is low calcium and vitamin D metabolism.
• Diet counseling for prosthodontic patients
is necessary to correct imbalances in
nutrient intake.
• Denture patients with excessive RRR report
lower calcium intake and poorer calcium
phosphorus ratio, along with less vitamin D.

43. • Nutritionally deficient denture-bearing tissues
will be uncomfortable for the denture, it is
essential to improve the nutritional status of the
elderly patients through proper counselling and
nutritional supplements, for prosthodontic
treatment to be successful.

44. TREATMENT OF RESIDUAL
RIDGE
• A close correlation between a patient’s satisfaction
with dentures and the anatomical conditions of the
residual ridge is not always present.
• However, in long-term complete denture wearers, the
morphological changes and the reduction of the
residual ridges present serious clinical management
challenges on how to provide adequate support,
stability, and the retention of new dentures. These
problems are approaches by various preprosthetic
surgical initiatives.

45. PREPROSTHETIC SURGERY
• Excessive residual ridge resorption leads to
loss of sulcus width and depth with
displacement of muscle attachment more to
the crest of residual ridge.
• Osseous reconstruction surgeries, removal of
high frenal attachments, ridge augmentation
procedures, vestibuloplasties with skin or
mucosal grafts etc may be required to correct
these conditions.

46. Inferior Border AugmentationSuperior Border Augmentation
Interpositional Grafts
RIDGE AUGMENTATION PROCEDURES

47. OVERDENTURES
• Overdentures help in
minimizing ridge resorption
contribute towards enhanced
retention, stability, support of
prosthesis along with
preservation of proprioception.
Clinicians must try to retain
residual roots whenever
possible.

48. OVERDENTURES
The advantages of overdentures over conventional
dentures are:
• The denture bearing mucosa of the residual ridges
are spared abuse.
• Maintenance of the alveolar bone.
• Sensory feedback.
• Tactile sensitivity discrimination.
• Masticatory performance.

49. OSSEOINTEGRATION AND
IMPLANT SUPPORTED
STRUCTURES
• The introduction of osseointegrated implants
has eclipsed traditional preprosthetic surgical
techniques. The use of implant-supported
overdentures resembles the same clinical
situation of teeth supported overdentures.
These are cost-effective treatment option for
the completely edentulous individual.

50. ADVANTAGES OVER
COMPLETE DENTURES:
• Better retention, stability
and speech
• Improved chewing and
speech
• Reduced prosthesis size
• Reduced anterior bone loss

51. Metal based denture with soft liner is advocated in
patients with severely atrophic residual ridges.
Metal base provides-
◦ Weight necessary to facilitate retention
◦ MaintainAdequate strength with modest extensions
The soft liner accomodates ridge irregularities and
changes.
METAL BASED DENTURES

52. IMMEDIATE DENTURES
Some authors claim that extraction followed by
immediate dentures reduces the ridge resorption.

53. • The ultimate aim of a successful prosthesis is
stability in function and excellent esthetics.
• The expectations of edentulous patients are highly
variable therefore the outcome of patient treatment
varies significantly.
• Patients should be educated regarding the type and
extent of treatment that is ideal for them, the
prognosis of the treatment outcomes with various
types of removable or fixed prostheses and the
alternatives that are available.
CONCLUSION

54. REFERENCES
• Prosthodontic treatment for edentulous
patients (12th Edition) – Zarb – Bolender
• Textbook of prosthodontics (2nd Edition) – V.
Rangarajan