Dr Balendra pratap singhDr Balendra pratap singhMDS, MAMS, FISDR, FPFA, FAAMP, ICMR-IFMDS, MAMS, FISDR, FPFA, FAAMP, ICMR-IFAssistant professor Assistant professor Deptt. Of ProsthodonticsDeptt. Of Prosthodontics

Problems of Residual ridge resorption

“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 The residual ridge resorption is a life-long resorption is a life-long process.process.

The rate of reduction in The rate of reduction in size of the residual ridge size of the residual ridge is is maximum in the first maximum in the first 3-6 months 3-6 months and then and then gradually tapers off. gradually tapers off.

Coupled process between:Coupled process between:1.1. Bone deposition by osteoblastsBone deposition by osteoblasts

2.2. Bone resorption by osteoclastsBone resorption by osteoclasts 5-7% of bone mass recycled weekly5-7% of bone mass recycled weekly All spongy bone replaced every 3-4 All spongy bone replaced every 3-4

years.years. All compact bone replaced every 10 All compact bone replaced every 10

years.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)Based on Bone Height (Mandible only) Type I : Residual bone height of 21 mm or greater Type I : Residual bone height of 21 mm or greater

measured at the least vertical height of the mandible.measured at the least vertical height of the mandible.

Type II : Residual bone height of 16 - 20 mm Type II : Residual bone height of 16 - 20 mm measured at least vertical height of the mandible. measured at least vertical height of the mandible.

Type III : Residual alveolar bone height of 11 - 15 mm Type III : Residual alveolar bone height of 11 - 15 mm

measured at the least vertical height of the mandible.measured at the least vertical height of the mandible.

Type IV : Residual vertical bone height of 10 mm or Type IV : Residual vertical bone height of 10 mm or less measuredless measured at the least vertical height of the at the least vertical height of the mandible.mandible.

RRR occurs worldwide in RRR occurs worldwide in Males and females Males and females Young and oldYoung and old Sickness and healthSickness and health With or without denturesWith or without dentures Unrelated to primary reason for the Unrelated to primary reason for the

extraction of teeth ( caries & pdl disease )extraction of teeth ( caries & pdl disease )

Studies also suggest incresed knife edge Studies also suggest incresed knife edge tendency in mandibular residual ridge in tendency in mandibular residual ridge in women compared to men.women compared to men.

RRR is accelerated in the first 6 months with RRR is accelerated in the first 6 months with more loss in mandible than maxilla.more loss in mandible than maxilla.

According to Boucher,According to Boucher,

During the first year after tooth extraction, During the first year after tooth extraction,

the reduction in residual ridge height in the reduction in residual ridge height in the midsagittal plane is the midsagittal plane is

2-3 mm for maxilla 2-3 mm for maxilla

4-5 mm for mandible 4-5 mm for mandible

Annual rate of reduction in height Annual rate of reduction in height

0.1-0.2 mm for mandible0.1-0.2 mm for mandible

4 times less in the maxilla4 times less in the maxilla

Maxilla resorbs upward and inward Maxilla resorbs upward and inward toto

become become progressively smaller progressively smaller because of the because of the direction and inclination of the roots of the teeth and direction and inclination of the roots of the teeth and the alveolar process. the alveolar process.

The opposite is true of The opposite is true of the the mandible, whichmandible, which

inclines outward inclines outward and becomes and becomes progressively progressively wider wider according to its edentulous age. according to its edentulous age.

This progressive change of the edentulous This progressive change of the edentulous mandible and maxilla makes many patients appear mandible and maxilla makes many patients appear prognathicprognathic..

RRR is generally more in mandible than in RRR is generally more in mandible than in maxilla and but the reverse may also maxilla and but the reverse may also occur….occur….

So one must treat the So one must treat the “PARTICULAR “PARTICULAR PATIENT, NOT THE AVERAGE PATIENT, NOT THE AVERAGE PATIENT!”!PATIENT!”!

Acc. To Atwood…..RRR is a multifactorial Acc. To Atwood…..RRR is a multifactorial biomechanical disease caused by a biomechanical disease caused by a combination of combination of ANATOMIC FACTORSANATOMIC FACTORS MECHANICAL FACTORSMECHANICAL FACTORS METABOLIC FACTORSMETABOLIC FACTORS

It is postulated that RRR varies with the It is postulated that RRR varies with the quantity and quality of the bone of residual quantity and quality of the bone of residual ridges.. ridges..

i.e. the more bone there is, the more RRR will i.e. the more bone there is, the more RRR will ultimately be.ultimately be.

RRR α Anatomic factors

RRR varies directly with certain systemic or RRR varies directly with certain systemic or localized bone resorptive factors and localized bone resorptive factors and inversely with certain bone formation factors.inversely with certain bone formation factors.

RRR BONE RESORPTION FACTORS BONE FORMATION FACTORS

BONE RESORPTION FACTORS

LOCAL SYSTEMIC

-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

- Correct amount of circulating estrogen, thyroxine, growth hormone,calcium,phosphorus,vitamin D ,fluoride

-Osteoporosis

- Hypophosphetemia

- Parathormone

- Calcitonin

Bone that is used by regular and physical Bone that is used by regular and physical activity will tend to strengthen within certain activity will tend to strengthen within certain limits, than the bone that is in “limits, than the bone that is in “disuse disuse atrophyatrophy”, while others postulated that due to ”, while others postulated that due to denture wearing RRR is caused due to an denture wearing RRR is caused due to an “abuse” bone resorption. “abuse” bone resorption.

Perhaps there is truth is both the hypotheses.Perhaps there is truth is both the hypotheses.

The fact is that with or without dentures some The fact is that with or without dentures some patients have little or no RRR and some have patients have little or no RRR and some have severe RRR.severe RRR.

Apparent loss of sulcus width Apparent loss of sulcus width and depth. and depth.

Displacement of muscle Displacement of muscle attachment close to the ridge. attachment close to the ridge.

Loss of vertical dimension of Loss of vertical dimension of occlusion. occlusion.

Reduction of the lower face Reduction of the lower face height. height.

Increase in relative Increase in relative prognathiaprognathia

Changes in inter alveolar Changes in inter alveolar relationship following RRR relationship following RRR

Morphological changes of Morphological changes of

the alveolar bone such as the alveolar bone such as sharp, spiny uneven sharp, spiny uneven residual ridges.residual ridges.

Location of mental Location of mental foramina close to the foramina close to the ridge crest. ridge crest.

““Treatment of RRR is ideally by preventing it.”Treatment of RRR is ideally by preventing it.”

a.a. Prevention of loss of natural teethPrevention of loss of natural teethb.b. Change in design of dentureChange in design of denture Impression procedures Impression procedures

Minimal pressure impression technique.Minimal pressure impression technique. Selective pressure impression technique: places Selective pressure impression technique: places

stress on those areas that best resist functional stress on those areas that best resist functional forcesforces

Adequate relief of non stress bearing areas eg. Adequate relief of non stress bearing areas eg. Crest of mandibular ridge.Crest of mandibular ridge.

Broad area of coverage helps in reducing the Broad area of coverage helps in reducing the force /unit area (force /unit area (Snow Shoe Effect)Snow Shoe Effect)

Avoidance of inclined planes to minimize dislodgment Avoidance of inclined planes to minimize dislodgment of dentures and shear forces.of dentures and shear forces.

Centralization of occlusal contacts to increase stability Centralization of occlusal contacts to increase stability and maximize compressive forces.and maximize compressive forces.

Provision of adequate tongue room to improve stability Provision of adequate tongue room to improve stability of denture in speech and mastication.of denture in speech and mastication.

Adequate interocclusal distance during jaw rest to Adequate interocclusal distance during jaw rest to decrease the frequency and duration of tooth contact.decrease the frequency and duration of tooth contact.

Occlusal table should be narrowOcclusal table should be narrow

Diet counseling for prosthodontic Diet counseling for prosthodontic patients is necessary to correct patients is necessary to correct imbalances in nutrient intake. imbalances in nutrient intake.

Denture patients with excessive RRR Denture patients with excessive RRR report lower calcium intake and poorer report lower calcium intake and poorer calcium phosphorus ratio, along with less calcium phosphorus ratio, along with less vitamin D. vitamin D.

Excessive RRR leads to loss of sulcus width Excessive RRR leads to loss of sulcus width and depth with displacement of muscle and depth with displacement of muscle attachment more to the crest of residual attachment more to the crest of residual ridge, ridge, osseous reconstruction surgeries, osseous reconstruction surgeries, removal of high frenal attachments, removal of high frenal attachments, augmentation procedures, vestibuloplasties augmentation procedures, vestibuloplasties etc may be required to correct these etc may be required to correct these conditions.conditions.

  

Pre-prosthetic surgery

Immediate denturesImmediate dentures:: Some authors claim that extraction Some authors claim that extraction

followed by immediate dentures reduces the followed by immediate dentures reduces the ridge resorption but this has still to be ridge resorption but this has still to be

provedproved..

  

Overdenture: tooth or implant Overdenture: tooth or implant supportedsupported

1.The denture bearing mucosa of 1.The denture bearing mucosa of the residual ridges are spared the residual ridges are spared abuse.abuse.2.Maintenance of the alveolar 2.Maintenance of the alveolar bonebone3.Sensory feedback3.Sensory feedback4.Minimal load thresholds4.Minimal load thresholds5.Tactile sensitivity discrimination5.Tactile sensitivity discrimination6.Masticatory performance6.Masticatory performance7.Reduction of Psychological 7.Reduction of Psychological traumatrauma

Thank you Thank you