Problems of Residual ridge resorption
Dr Balendra pratap singh
MDS, MAMS, FISDR, FPFA, FAAMP, ICMR-IF
Assistant professor
Deptt. Of Prosthodontics

“Alveolar bone is defined as the bony portion of the maxilla and
the mandible in which roots of the teeth are held by fibers of
periodontal ligament”. [GPT-8]
 “Residual
alveolar ridge is that portion of the
alveolar ridge and its soft tissue covering
which remains following the removal or loss
of teeth”.
[GPT-8]

The residual ridge resorption is
a life-long process.

The rate of reduction in size of
the residual ridge is maximum
in the first 3-6 months and
then gradually tapers off.

Coupled process between:
1.
2.



Bone deposition by osteoblasts
Bone resorption by osteoclasts
5-7% of bone mass recycled weekly
All spongy bone replaced every 3-4 years.
All compact bone replaced every 10 years.
Prevents mineral salts from crystallizing; protecting against
brittle bones and fractures

The rate of RRR varies, from one individual to another;
at different phases of life and even at different sites in
the same person.

The clinical significance of such remodelling is that the
functionality of removable prostheses, which rely greatly
on the quantity and architecture of the residual ridge,
may be adversely affected.
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 11 - 15 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.

RRR occurs worldwide in
 Males and females
 Young and old
 Sickness and health
 With or without dentures
 Unrelated to primary reason for the extraction
of teeth ( caries & pdl disease )



Studies also suggest incresed knife edge tendency
in mandibular residual ridge in women compared
to men.
RRR is accelerated in the first 6 months with more
loss in mandible than maxilla.

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

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 according
to its edentulous age.

This progressive change of the edentulous mandible and
maxilla makes many patients appear prognathic.


RRR is generally more in mandible than in maxilla
and but the reverse may also occur….
So one must treat the “PARTICULAR PATIENT,
NOT THE AVERAGE PATIENT!”!

Acc. To Atwood…..RRR is a multifactorial
biomechanical disease caused by a combination of
 ANATOMIC FACTORS
 MECHANICAL FACTORS
 METABOLIC FACTORS
RRR α Anatomic factors

It is postulated that RRR varies with the quantity and
quality of the bone of residual ridges..
i.e. the more bone there is, the more RRR will ultimately
be.

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
BONE RESORPTION FACTORS
SYSTEMIC
LOCAL
-Prostaglandins
- Correct amount of circulating
estrogen, thyroxine, growth
hormone,calcium,phosphorus,vita
min D ,fluoride
-Human gingival bone resrption factor
-Osteoporosis
-Heparin
- Hypophosphetemia
-Trauma due to ill fitting dentureswhich
leads to increased or decreased
vascularity and changes in oxygen
tension
- Parathormone
-Endotoxins from dental plaque
-Osteoclast activating factor(OAF)
- Calcitonin

Bone that is used by regular and physical activity will tend
to strengthen within certain limits, than the bone that is
in “disuse atrophy”, while others postulated that due to
denture wearing RRR is caused due to an “abuse” bone
resorption.

Perhaps there is truth is both the hypotheses.

The fact is that with or without dentures some patients
have little or no RRR and some have severe RRR.

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.

Increase in relative prognathia

Changes in inter alveolar
relationship following RRR

Morphological changes of the
alveolar bone such as sharp,
spiny uneven residual ridges.

Location of mental foramina
close to the ridge crest.

“Treatment of RRR is ideally by preventing it.”
a.
Prevention of loss of natural teeth
b.
Change in design of denture

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.
Broad area of coverage helps in reducing the force /unit area
(Snow Shoe Effect)

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.

Adequate interocclusal distance during jaw rest to decrease the
frequency and duration of tooth contact.

Occlusal table should be narrow

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.
Pre-prosthetic surgery
Excessive RRR 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, augmentation
procedures, vestibuloplasties etc may be required to
correct these conditions.
Immediate dentures:
Some authors claim that extraction followed by
immediate dentures reduces the ridge resorption but
this has still to be proved.
Overdenture: tooth or implant supported
1.The denture bearing mucosa of the
residual ridges are spared abuse.
2.Maintenance of the alveolar bone
3.Sensory feedback
4.Minimal load thresholds
5.Tactile sensitivity discrimination
6.Masticatory performance
7.Reduction of Psychological trauma
Thank you