Dr Balendra pratap singh

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Problems of Residual ridge resorption

• Dr Balendra pratap singh
• MDS, MAMS, FISDR, FPFA, FAAMP, ICMR-IF
• Assistant professor
• Deptt. Of Prosthodontics

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• 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

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• 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

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• 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.

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Changes in the Residual Ridge after tooth
extraction
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Bone is Dynamic! Bone
is constantly remodeling and recycling

• Coupled process between
• 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
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• 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.

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According to the American college of
prosthodontists McGarry et al, J Prosthodont
8(1)27-39, 1999

• 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.

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EPIDEMIOLOGY OF RRR

• 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.

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Amount and rate of bone Resorption

• 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

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direction of bone resorption

• 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.

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• 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!!

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Etiology of RRR

• Acc. To Atwood..RRR is a multifactorial
  biomechanical disease caused by a combination of
• ANATOMIC FACTORS
• MECHANICAL FACTORS
• METABOLIC FACTORS

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1. ANATOMIC FACTORS
RRR a 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.

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2.METABOLIC FACTORS

• 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
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BONE RESORPTION FACTORS
SYSTEMIC
LOCAL

• - Correct amount of circulating estrogen,
  thyroxine, growth hormone,calcium,phosphorus,vitam
  in D ,fluoride
• -Osteoporosis
• - Hypophosphetemia
• Parathormone
• Calcitonin

-Endotoxins from dental plaque -Osteoclast
activating factor(OAF) -Prostaglandins -Human
gingival bone resrption factor -Heparin -Trauma
due to ill fitting dentureswhich leads to
increased or decreased vascularity and changes in
oxygen tension
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Mechanical factors

• 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.

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Consequences of 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

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• 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.

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Treatment and prevention

• Treatment of RRR is ideally by preventing it.
• Prevention of loss of natural teeth
• 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)

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• 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

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• 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.

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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.
•  

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• Immediate dentures
• Some authors claim that extraction followed
  by immediate dentures reduces the ridge
  resorption but this has still to be proved.
•  

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• 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

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• Thank you