RESIDUAL RIDGE RESORPTION– – – – – – – – – – – – INTRODUCTION DEFINITIONS CLASSIFICATION OF RRR PATHOLOGY OF RRR PATHOPHYSIOLOGY OF RRR PATHOGENESIS OF RRR EPIDEMIOLOGY OF RRR ETIOLOGY OF RRR DIAGNOSTIC AIDS TO DETECT RRR CONSEQUENCES OF RRR MANAGEMENT CONCLUSION • INTRODUCTION • Resorption is defined as loss of tissue substance through physiologic or pathologic processes. The tissues remaining following the extraction of the teeth (Residual alveolar ridge) changes shape and are reduced in size at varying rates in different individuals and in the same individual at different times. [Gray’s Anatomy] • “Alveolar process may be defined as that part of the maxilla and mandible that form and supports the sockets of the teeth”. constantly changing. [Orban’s Dental Histology] . living.• DEFINITIONS : • “Bone is defined as a highly vascularised. mineralized connective tissue”. • • • • • • BONE QUANTITY : (Branemark) Class A : Most of the alveolar bone is present Class B : Moderate residual ridge resorption occurs Class C : Advanced residual ridge resorption occurs Class D : Moderate resorption of the basal bone Class E : Extreme resorption of the basal bone .• Classification of RRR : • According to Branemark et al in 1985. ridges were classified on the basis of bone quantity and quality by radiographic means. • Class 3 : A thin layer of cortical bone surrounds a core of dense trabecular bone. • Class 2 : A thick layer of compact bone surrounds a core of dense trabecular bone.• BONE QUALITY : • Class 1 : Almost the entire jaw is composed of homogenous compact bone. • Class 4 : A thin layer of cortical bone surrounds a core of low-density trabecular bone. . • Class III : Two third or more of the mandibular height lost. . • Class II : From one third to two thirds of the vertical height lost.• BY WICAL AND SWOOPE : • Class I : Upto one third of the original vertical height lost. • Class 1 : High degree of resorption . both the genial tubercle and the mylohyoid lines are below the level of the alveolar ridge. the genial tubercle is above the level of the alveolar ridge. the genial tubercle and the mylohyoid are either just below the highest point of the alveolar ridge or at the same level. and the mylohyoid lines are at the same level or above the alveolar ridge. • Class 2 : Extensive resorption .• BY KALK AND BAATA : • Degree of alveolar bone resorption in mandible : • Class 0 : Moderate resorption . . if any. . • Class I : Extensive degree of resorption. resorption with there being a difference in height between the lowest point on the mucosal membrane and the highest point on the alveolar ridge. The alveolar ridge is narrow and there is little difference in height between the lowest points on the mucosal membrane and palate and the highest point on the alveolar ridge. There may be a flabby ridge. There is no flabby ridge.• Degree of alveolar bone resorption in maxilla : • Class 0 : Little. 5 inch of space exists between mylohyoid ridge and floor of mouth.5 inch of space exists between mylohyoid ridge and floor of mouth. Retention of the lower denture is almost impossible.• NIEL’S CLASSIFICATION : • Class 1 : Approximately 0. • Class 2 : Less than 0. . • Class 3 : The mylohyoid muscle is at the same level as the mylohyoid ridge. This is favorable for lower denture. well round • Order 6 : Depressed . well rounded • Order 4 : Knife-edge • Order 5 : Low.• ATWOOD’S CLASSIFICATION : Order 1 : Pre-extraction • Order 2 : Post-extraction • Order 3 : High. . Group 3 : Absence of residual ridge. Group 2 : Painful atrophic ridge Group 3 : Absence of residual ridge • • • • • ZELSTER’S CLASSIFICATION : Group 1 : High muscle attachment & minimal RRR. Group 2 : Severe residual ridge resorption with pain. Group 4 : Severe resorption of basal bone.• • • • MERCIER’S CLASSIFICATION : Group 1 : High crestal muscles and non resorbed ridge. D2 -Thick dense to porous cortical bone on crest and cortical tabecular bone with in. • D3 . non mineralized bone . BONE -DENSITY D1 -Dense cortical bone.Thin porous cortical bone on crest and fine trabecular bone with in • D4 .Immature.Fine trabecular bone • D5 .• • • • MISCH’S CLASSIFICATION : Based on bone density. 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. . • Type III : Residual alveolar bone height of 11 .• Classification according to the American college of prosthodontists : • 1.20 mm measured at least vertical height of the mandible. • Type II : Residual bone height of 16 . 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. .COMPOSITION OF BONE CELLS OF BONE Osteoprogenitor cells Osteoblast cells. Osteocytes Osteoclast cells. Di.8% (sulfated and Non sulfated) Sialoproteins – 0.ORGANIC PART – 33% .35% Collagen – 88% .4% . Poly and Oligosaccharides).35% Lipids – 0. Proteoglycanes – 0.11%. Glycoproteins – 6% .90% (Type – I) Non collagen – 10% .9% (Mono. 67% Calcium & Phosphates – 95% (Hydroxyapatite Crystals – Ca10(Po4)6 (OH)2) Magnesium Trace elements – Nickel.INORGANIC PART – 65% . . Cadmium. Iron. Fluoride. Magnesium. Zinc and Molybdenum. *They are responsible for mineralization and are derived from a multipotent mesenchymal cell. . *Osteoblasts exhibit high levels of alkaline phosphate on the outer surface of their plasma membranes. *They constitute a cellular layer over the forming bone surface.OSTEOBLASTS *Uninucleated cells that synthesize both collagenous and noncollagenous bone protein. *A variety of cytokines. .**Other enzymes that participate in their activity are *ATPase and pyrophosphates *Type I and type V collagen *Several noncollagenous proteins. *The more rapid the formation. *The number of osteoblasts that become osteocytes varies depending on the rapidity of bone formation. . a more osteocytes are present per unit volume. some of them become entrapped in lacunae and are then called osteocytes.OSTEOCYTE *As osteoblasts secrete bone matrix. . *They are generally seen in a cluster rather than singly. *Osteoclast is characterized by acid phosphatase within its cytoplasmic vesicles and vacuoles. the multinucleated osteoclast is a much larger cell. which distinguishes it from other giant cells and macrophages.OSTEOCLAST *Compared to all other bone cells and their precursors. *Osteoclast are also rich in lysosomal enzymes. **Typically osteoclasts are found against the bone surface occupying shallow. hollowed out depressions. . called Howship’s lacunae. Thus the sequence of resorptive events is considered to be Attachment of osteoclasts to mineralized surface of bone. Degradation of this exposed organic matrix to its constituent amino acids by the action of released enzymes. which demineralizes bone and exposes the organic matrix. . Uptake of mineral ions and amino acids by the cell. Creation of a sealed acidic environment through action of the proton pump. 3.CLASSIFICATION OF BONE 1. *Coarse Trabeculae. *Lamellar bone. According to bone mass *Fine Trabeculae. Microscopically bones are composed of *Woven bone. *Bundle bone and *Composite bone. *Porous Compacta and *Dense Compacta. According to density as *Compact bone *Trabecular bone. 2. . • Stabilize unloaded Endosseous implants during initial healing.Woven bone • Highly cellular. . • Formed rapidly (30-50 µm/ day or more) in response to growth or injury. • Low mineral content. • Random fiber orientation and minimal strength. • Densely mineralized and highly organized matrix.Lamellar bone • Principle load bearing tissue of adult skeleton. • Predominant component of mature cortical and trabecular bone. . • Formed relatively slowly (<1 µm/ day). Bundle bone • Characteristic of ligament and tendon attachments along bone-forming surfaces. . • Sharpey’s fibers from adjacent connective tissue insert directly into bone. • Bundle bone is formed adjacent to the periodontal ligament of natural teeth. • Important in achieving stabilization of an implant during the rigid integration process. • Got adequate strength for load bearing. .Composite bone • High quality lamellar bone deposited on a woven bone matrix. . but the majority of alveolar bone formation occurs during tooth eruption.**Alveolar Bone forms the bony sockets of the jaw bones in which the roots of the natural teeth are suspended by the attachment of the periodontal ligament fibers (“Gomphosis” ) **Some alveolar bone is formed during tooth development. .*The presence of alveolar bone in the jaw bones is totally dependent on the roots of the natural teeth. without the teeth the alveolar bone need not exist. • PATHOLOGY OF RRR • GROSS PATHOLOGY : – Patient has expression “ My gums have shrunk “ – Basic structural change is reduction in size of bony ridge under the mucoperiosteum – Localized loss of bone structure – Overlying mucoperiosteum Excessive & redundant No redundant soft tissue Difficult to understand Lammie postulates . • LAMMIE postulates . one factor in RRR may be a cicatrizing mucoperiosteum that is seeking a reduced area . resulting in pressure resorption of the underlying bone • Longitudinal radiographic cephalometric studies have provided excellent visualisation of gross patern of bone loss from lateral view point . With reduction of bone in size and shape .Careful superimposition of portions of tracings of lateral ceph. .• Gross anatomic studies of dried jaw bones have shown a wide variety of shapes and sizes of residual ridges • A simplified method for categorizing residual ridge form is order 1----order 6 Uses : useful clinically as well as for research purpose : helps to differentiate various stages of RRR in pts. In dry specimens *External cortical surface of maxilla and mandible are uniformly smooth & crestal area of residual ridge shows porosities and imperfections *Bones with more severe RRR display gross porosities of medullary bone on the crest of ridge . • Gross bone loss of residual ridge revealed by superimposition of portion of two cephalometric radiographs made 16 years apart . • RRR does not stop with the residual ridge but may go well below where the apices of teeth are… • There can be a thin cortical plate on inferior border of mandible or virtually no maxillary alveolar process . • Panoramic radiograph showing severe RRR in both maxilla and mandible in contrast to dentulous area that support three mandibular teeth . 26 .• Radiographs of mid-saggital sections of eight mandibles illustrating various orders of residual ridge form Atwood DA JPD 1971 Vol. • Clinical examination of ridge form depends on Good judgment of clinician • Palpation in the mouth accurately determines underlying bone • Lateral ceph. determines amount of bone and rate of RRR over a period of time • Panoramic radiographs simple & useful method of estimating amount of RRR . *Original alveolar crest ht. can be predicted by measurement of distance from inferior border of mandible to mental foramina Wical and Swoope • MICROSCOPIC PATHOLOGY : • Evidence of osteoclastic activity on the external surface of crest of residual ridge • Scalloped margins of howship’s lacunae contain visible osteoclasts • Why there is only decrease in size of residual ridges ??? • Reason : • Scalloped external surface contain osteoclasts only • External surface of bone is covered by fibrous non osteogenic periosteum . • ATWOOD DA : JPD 1963 • There is wide variation in configuration density and porosity of not only residual ridge but also entire cross-section of anterior mandible • Mandibular osteoporosis occurs with – Increased variation in density of osteons – Increased no. of incompletely closed osteons – Increased endosteal porosity – Increased plugged osteons . thus accentuating the chin point.**Remodeling changes occur in the mandible that account for the typical edentulous facial anatomy. . The overall length of the mandible does not decrease but may in fact increase as new bone is added to the mental protuberance. but in both an inferior and lingual direction in the incisor region. Reduction in the residual ridges occurs in an inferior direction in the molar and premolar areas. . There is generalized thinning of the anterior and posterior aspects of the mandibular ramus. There is an anterior displacement of the mandible (protrusive position) because of residual ridge reduction. mandibular rotation (Change in the angulation of the body relative to the mandibular ramus). and deposition of bone in the mental region. . • PATHOPHYSIOLOGY OF RRR BONE REMODELLING OSTEOBLAST S BONE FORMATION OSTEOCLASTS BONE RESORPTION Exceeds in case of Exceeds in case of *GROWTH *PDL DISEASE *OSTEOPOROSIS . bone Practical terms rate of resorption so much that patient ends up with no cortical bone at crest of ridge .• RESIDUAL RIDGE RESORPTION PATHOLOGIC PROCESS?? PHYSIOLOGIC PROCESS?? Bone once lost cannot be built back by removing causative factors Removal of tooth eliminates the raison d etry for alveolar bone Clinical facts :1. RRR varies & can proceed far beyond alv. RRR not inevitable 2. EXTERNAL OSTEOCLASTIC ACTIVITY ENDOSTEAL BONE FORMATION Fails to keep pace Absence of cortical layer of bone Exposure of medullary layer to external surface Defects on the crest of ridge . • Pathogenesis of RRR: • RRR is a chronic progressive irreversible cumulative disease which proceeds slowly over a long period of time from one stage to next . 4 0.75 0.13 2.8 **measurments in mm .36 0.• Carlson and Pearson at al • Post extraction study of mandibular bone loss Pts.7 5 4.5 2.9 1. with Least RRR Mean RRR Most RRR First 2 yrs First 5 yrs 3 to 5 yrs 0.5 1. • Tallgren Atwood & Coy studied rate of residual ridge resorption for 25 years – Mean ratio of anterior maxillary RRR to anterior mandibular RRR was 1:4 – RRR is more in mandible than in maxilla and reverse can also occur – So one must treat the ‘PARTICULAR PATIENT. NOT THE AVERAGE PATIENT . .• EPIDEMIOLOGY OF RRR : • Methods • Longitudinal cephalometric. time consuming and expensive • Panoramic methodology or radiograph • By palpation • There have been no large scale studies of RRR • Longitudinal cephalometric studies of few subjects have been done • Methods of Measure Bone Formation:– Tetracycline labeling – Bone seeking tracer such as Ca-45. • 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 (KET) in mandibular residual ridge in women compared to men. • KET = Change in area /Change in height . As Age Advances Mineral content in bones Increase Decrease MALES FEMALES Due to osteoporosis that takes place in females Leading to knife edge ridges . • Etiology of RRR : • RRR is a multifactorial biochemical disease caused by a combination of – ANATOMIC FACTORS – MECHANICAL FACTORS – METABOLIC FACTORS (1998 by Leili Jahamgeri ) – PROSTHETIC FACTORS – GENETIC FACTORS Anatomic Metabolic Mechanical . ANATOMIC FACTORS – RRR ANATOMIC FACTORS LIKE • SIZE & SHAPE OF RIDGE • TYPE OF BONE REMOVED • AMOUNT OF BONE • QUALITY OF BONE • SPACES BETWEEN RIDGES • MUSCLE ATTACHMENTS • ACTION OF TONGUE .• 1. • 2. MECHANICAL FACTORS • RRR FORCE DAMPING EFFECT F Amount O Duration R Frequency C Direction & E Distribution . So it is ideally constructed for the absorption and dissipation of energy. which is a viscoelastic material.• Dampening effect takes place in the mucoperiosteum. flatter and more cancellous than its mandibular counterpart. • Frost pointed out that the trabacule in cancellous bone are arranged parallel to direction of compression deformation. . • Maxillary bone (RR) is frequently broader. Correct amount of circulating .Parathormone .Calcitonine D Flouride .Osteoporosis Androge n Thyroxin e .• METABOLIC FACTORS : RRR BONE RESORPTION FACTORS BONE FORMATION FACTORS BONE RESORPTION FACTORS LOCAL -Endotoxins from dental plaque -Osteoclast activating factor -Prostaglandin -Heparin -Trauma SYSTEMIC Estroge n .Hypophosphetemia Vitamin. • PROSTHETIC FACTORS – – – – INCREASED OCCLUSAL FORM VERTICAL DIMENSIONAL CHANGES CUSP FORM EXCESSIVE LOAD BY OVERLY FITTING DENTURES – – – – – OTHERS : BONE LOSS DUE TO UNKNOWN CAUSES AGE RELATED BONE LOSS GENETIC FACTORS DRUG THERAPY . • RRR ANATOMIC FACTORS + BONE RESORPTION FACTORS + FORCE BONE FORMATION FACTORS DAMPING + 1 TIME . metabolic and mechanical). the importance of time since extraction to the bone loss should be emphasized by adding in an inverse ratio.• RRR ANATOMIC FACTORS + BONE RESORPTION FACTORS + FORCE BONE FORMATION FACTORS DAMPING • In addition to the three major categories of factors (anatomic. • Various etiologic factors and their correlation Etiologic factor Correlation with RRR Source Anatomic factor Mandible Short & square face Large alv. Increased RRR *Tallegren *Atwood & coy *Tallegren Increased RRR *Wictorin No correlation of RRR with bone density *Wilson Increased RRR *Atwood & coy *Gazabatt et al *Wictorin . process Density of alveolar bone Labial alveoloplasty 4 x more RRR than max. • Various etiologic factors and their correlation Etiologic factor Correlation with RRR Source Prosthodonti cImmediate Decreased RRR dentures Overdentures Zero degree teeth Decreased RRR Increased RRR *Wictorin *Carlson et al *Crum & Rooney *Winter et al Woelfel et al . ridge Calcium & vit – D supplement Sodium flouride supplement Knife edge type mandible Decreased RRR No correlation but better calcification Source *Atwood & Coy *Wictorin *Carlson et al * Atwood & Coy *Nishimura et al *Mercier & Inoue *Wical & Brussee Fenton & ElKassem .• Metabolic and systemic factors Etiologic factor Correlation with RRR Age & sex No correlation with the rate of RRR Osteoporosis No correlation with the ridge height Smaller max. • Functional factors Etiologic factor Correlation with RRR Intensive denture wearing Regular denture wearing Other factors Bioelectric potential Increased RRR Combination syndrome No correlation with the rate of RRR Statistically insignificant trend Decreased RRR by exogenous pulsed electromagnetic field in dogs Source *Campbell *Kelly *Carlson et al * Atwood & Coy *Bergman *Nicol et al *Van der Kuij et al . • Tetracycline labeling : Injected into the body through oral or pariental administration and should be repeated after every week for 5 weeks. only in the new sites of bone formation tetracycline can be readily identified in the bone as tetracycline calcium chelate formed is fluoroscent and can be viewed by fluorescence microscopy. .• DIAGNOSTIC AIDS TO DETECT RRR • Radiographic : widely used to detect bone resorption and formation by taking periodic radiographs. This tetracycline is taken up by the bone. • In this method mercury is introduced into pores by pressure and a measure of the pore volume as a function of pore diameter is obtained . periosteocytic lacunar bone resorption).e.• Mercury porosimetry : Osteocytes are also capable of bone resorption (i. • To determine the quantitative importance of osteocytic resorption mercury porosimetry was used to makes a comparison between osteocytic and osteoclastic bone resorption. and vascular canals constitute a system of pores. which enlarges as a result of osteoclastic resorption. which enlarges as a result of osteoclastic resorption and vascular canal volume.• Since osteocyte lacunae. • Thus with this method it was able to quantitate osteocyte lacunae canalicular volume. canaliculi. this method can be applied to measure the volume of different classes of bone pores. . PG’ s AS MEDIATORS OF RRR . PG is not stored in cells in their final form but is quickly released in response to mechanical. therefore it is important to note that PG works as a local hormone. .PROSTAGLANDINS: MEDIATOR OF RRR • Prostaglandins (PG) has been demonstrated to mediate bone resorption in vitro and in vivo. physiologic and pathologic stimuli. • Its half life is short (less than 1min) and its various effects are limited only to adjacent cells. • The pharmacologic effect of NSAID’s such as indomethacin that are known to be inhibitors of PG bio synthesis have been investigated in order to control bone resorption in orthodontic tooth movement and in periodontal disease. because the cellular receptor against various bone resorbing hormones (including PG) have been found in osteoblasts but not in osteoclasts. • Bone resorption is a cellular phenomenon in which osteoclasts remove calcified substances from the bone. • It is hypothesized that osteoblasts are involved in bone resorption by coupling with osteoclasts.PROSTAGLANDINS: MEDIATOR OF RRR • These findings indicate that PG may have an important biologic role in the pathophysiology of localized bone resorption in the oral cavity. . • These findings may suggest the connective tissue contraction associated with extraction site and afterwards towards the crest of the residual ridge. The phenomenon may explain a mechanism of localized bone resorption at the crest area of the residual ridges by the PG activities. The continuous and localized bone resorption in RRR may be caused by continuous synthesis of local PG.•PROSTAGLANDINS: MEDIATOR OF RRR • PG’s are released from many kinds of cells including inflammatory cells such as neutrophilic granulocytes and macrophages as well as local mesenchymal cells such as osteoblasts and cells of the periodontal ligament. . Mechanical stimulation of osteoblastic cells in vitro caused a significant elevation cAMP and PG synthesis. the mandible and the fingers. . epiphysis of long bones.OSTEOPOROSIS • Osteoporosis is a systemic disease in the elderly. • Loss of the spongy spicules of bone that support the weight bearing parts of the skeleton can be seen in radiographs of regions of the skeleton that bear heavy loads. Osteoporosis shows a decrease in the skeletal mass without alteration in the chemical composition of bone. such as the vertebral column. . osteoporosis is caused by a variety of factors such as calcium loss.OSTEOPOROSIS • Osteoporosis is common in aging individuals. hormonal deficiency. • Progressive loss of alveolar bone may be a manifestation of osteoporosis . calcium deficiency. • In elderly men and women. especially post menopausal women when the estrogenic blood level is low. change in protein nutrition and decreased physical activity. • Location of mental formina close to the ridge crest. Reduction of the lower face height. spiny uneven residual ridges. . An anterior rotation of the mandible.• • • • • • • • Consequences of RRR : Apparent loss of sulcus width and depth. Loss of vertical dimension of occlusion. Increase in relative prognathia Changes in inter alveolar relationship following RRR • Morphological changes of the alveolar bone such as sharp. Displacement of muscle attachment close to the ridge. COMPLETE DENTURES Well fitting complete dentures Exerts Pressure on the alveolar bone Favourable Preserves alveolar bone Unfavourabl e Resorption of alveolar bone Campbell et al ( 1973 ) Edentulous patients wearing dentures had smaller residual ridges as compared to those not wearing dentures .• Prosthodontic treatment modalities : • 1. • WHY THERE IS MORE RESORPTION SEEN IN MANDIBLE THAN MAXILLA ??? • 1. Mandible provides a smaller surface area of support for the dentures • 2. Amount of cancellous bone is lesser as compared to maxilla *Dentures help to preserve the horizontal dimensions of residual ridge to some extent & vertical dimensions undergo resorption especially in mandible( 4 times) * Irreversible alveolar bone loss results from extraction regardless of how soon a denture is provided ( Atwood DA ) . • For maxilla • Extent of alveolar bone loss is a function of composition of opposing dentition • Maxilla opposing natural mandibular anteriors Less resorption Maxilla opposing artificial mandibular anteriors More resorption Combination syndrome **More resorption in anterior mandible seen in patients . wearing dentures day and night . 6mm for immediate overdentures . OVERDENTURES : • Distribute masticatory load between edentulous ridge and abutment • Transfer occlusal forces to alveolar bone through periodontal ligament of retained roots • Proprioceptive feedback from pdl prevents RRR • Crum & Rooney et al Measured the mean vertical bone loss in anterior mandible of 5.• 2.2 mm after 5 years for immediate dentures as compared to 0. • 3. REMOVABLE PARTIAL DENTURES : • Loss of periodontal attachment & marginal bone loss adjacent to abutment • Patient’s Free of pdl disease Adequate plaque control Minimum bone loss occurs **Occlusal problems occurs within 5 years as a result of vertical RRR with distal extension bases . • 4. FIXED PARTIAL DENTURES : • Marginal bone loss is minimum & is almost same as of uninvolved teeth • Mean annual rate of bone loss ~ 0 mm for up to 15 years if adequate plaque control is maintained . • 5. IMPLANT SUPPORTED PROSTHESIS: • Majority of bone loss (1-2mm ) occurs during healing and remodelling periods • Annual bone loss with implants is 0-0.08mm BONE LOSS Implant supported overdenture Maxilla Single implant prosthesis Implant fixed prosthesis > Mandible > Multiple implant prosthesis . distal to implant fixed prosthesis . distal to implant overdenture • 4 % reduction in bone ht.• Why more bone loss in maxilla with implants??? – Poor bone quality in maxilla – Increased mucosal irritation surrounding shorter abutments required • Jacob et al • 11 % reduction in bone ht. Management of RRR • 1) Two important factors to be considered are . Attitude of the patient – 2. – 1.e placing small masses of food over posterior teeth ( Heartwell ) . Remove dentures for atleast 8-12 hours for tissue rest Bitting with fork & knife i. Role of any systemic diseases as etiologic factors • • • • • • PREVENTION OF RRR Preventing loss of teeth Correct diagnosis & management of etiologic factors Correct hormonal & nutritional deficiencies if any. • Overdentures • Submerged roots • Hollow dentures • Metal based dentures • 3)Surgical management .Management • 1)Treatment of systemic factors involved in RRR • 2)Prosthodontic management – – – – a) Methods to improve denture foundation b) Design of the dentures c) Impression procedures d )Other options . hormonal imbalance and dietary deficiencies plays an important role in RRR • Prosthodontist should always consider the possibility of systemic cause for gross alveolar resorption .• 1)Treatment of systemic factors involved in RRR • Role of systemic disease as an etiological factor in gross alveolar resorption must be considered • Systemic conditions like osteoporosis. Prosthodontic management • Oral tissues .2.change shape with time Pressure transmitting surface Poorly adapted to the oral mucosa Resulting in Deformation of the denture supporting tissues Must be corrected . A)METHODS TO IMPROVE DENTURE FOUNDATION • • • • • • Use of temporary soft liner Regular finger massage of denture bearing mucosa Rest for denture supporting tissues Correction of old prosthesis to restore VD Good nutrition especially for geriatric patients Conditioning of patients musculature by jaw exercises . co-ordination & • Preparing the patient psychologically . • These materials allow deformed tissues to resume their normal shape • Abraded artificial teeth cause loss of facial height • Failure to carry out such corrective therapy can result in continuing distortion of oral tissues by dentures .• A course of treatment with tissue conditioning materials is often indicated. • • • • • B) DESIGN OF THE DENTURE . a)Broad area of coverage to decrease force per unit area ( SNOW SHOE EFFECT ) b)Decrease number of dental units & decreased buccolingual width of teeth ( decreased force to penetrate bolous of food ) c)Avoidance of inclined planes ( to minimise dislodgement of denture & shear forces ) d) Centralization of occlusal contacts ( to increase stability & maximise compressive forces ) e)provision of adequate tongue room & adequate interocclusal distance . – Anatomic vs Non anatomic teeth – Kyadd (1960 ) found that 33 o & 200 teeth caused more deformation and lateral stresses on the ridge than non anatomic teeth ( Cusp Trauma ) • g) occlusal pattern .• f) morphology of occlusal table . – Cuspless flat plane occlusion – Anatomic teeth with compensating curves – Careful setting & selective grinding to minimise lateral stresses . • h) Muscular Control ( Neutral Zone ) – Gardette (1800 ) first noted potential of muscular forces in denture control – Fish (1933) introduced concept of denture control – The secondary supporting surface i.e polished surface should have their shape determined by oral musculature ( neutral zone ) • i ) Tooth Material – Acrylic vs Porcelein – The property of transmission of impact forces is more important than wear resistance when considering health of alveolar ridges • Acrylic teeth • Cushioning effect • • Absorbs more forces than porcelein teeth PLUS Denture base material acrylic or metal • C ) IMPRESSION PROCEDURES ; • Bernard Levin ---Primary impression made with alginate and less water ( 25 % ) • Mac – Cold & Tyson ( BDJ 1997 )---Use of admixed technique for impressions ( 3:7 ) • Functional reline technique---use of open and close mouth procedures • Procedures for severely atrophied mandible (JPD 1993 ; 73 : 574 )--- peripheral borders are developed functionally with tissue conditioning material and final impression is taken with polysulphide impression material 59 :4) – Used in advanced atrophy of maxilla with adequate interocclusal distance – Double flask technique of Challian & barnett’s is used for maxilla ( weight reduction 25 % ) – Holtz technique with modifications for mandible . ( JPD 1988 .• Other options • Overdentures :distribute masticatory load b/w edentulous ridge and abutment – Rate of bone loss 0.8 mm in first year • Submerged roots : vital or non-vital – prevents resorption of ridges • Hollow dentures. 57:6 ) • Metal based denture with soft liner is advocated in patients with severely atrophic residual ridges • Metal base provides – Weight necessary to facilitate retention – Maintain Adequate strength with modest extensions • The soft liner accomodates ridge irregularities and changes . ( JPD 1987 .• Metal based dentures . If bone reorganization is accomplished by frequently induced intermittent stimuli. Exercise stimulation for a period of 12 weeks is usually adequate in most severe cases.• • • • Exercise stimulation of edentulous areas Exercise stimulation is a practical & desirable part of complete denture therapy. the supporting structures can be prepared for the occlusal function within limits of individual tolerance Intermittent use of Exogenous pulsed electromagnetic fields is demonstrated the effectiveness in decrease in the rate of residual ridge resorption . • Dietary guidelines for patients at risk of losing bone • Maintain a high daily calcium intake – Obtain four servings of low fat dairy foods or obtain equivalent amounts of calcium daily • Take calcium supplements if dietary intake is low • Choose calcium citrate maleate if patient has achlorhydria – If lactose intolerant. treat milk with lactase tablets or drops . poultry and fish – Use small amounts of processed foods high in sodium .• Dietary guidelines for patients at risk of losing bone • Prevent negative calcium balance – Limit daily alcohol and caffeine intake – Consume about 6 ounces of protein from meat. U of Vitamin D daily – Spend 15 minutes in the sun 3 times a week – Choose a multivitamin or calcium supplement that contains 4000 I.U of Vitamin D. • Discuss calcium or drug interactions that interface with calcium bioavailability with the physician .• Dietary guidelines for patients at risk of losing bone • Obtain 4000 I. Phosphorus •High intake may increase calcium urinary loss • Sodium •High intake increases urinary calcium losses • Fluoride •Stimulate • Caffeine •High • Alcohol •High osteoblasts. decreases bone resorption. decreases rate of bone loss in post menopausal women intestinal absorption of calcium. toxic effects on osteoblasts. increased calcium urinary losses . intake increases calcium urinary losses intake accelerates menopause. increases trabecular bone mass.•Nutrient •Effect • Calcium •Increases • Vitamin D •Increases • on metabolism bone mass. .g.. sulcus extension (vestibuloplasty) – Absolute methods e.Surgical treatment • Preprosthetic surgery includes . • Ridge preservation procedure as a preventive measure • Corrective or recontouring procedures of the defects and abnormalities • Ridge extension procedures – Relative methods e.g. ridge augmentation method . g..Surgical treatment • Reconstruction methods like correction of abnormal ridge relationship • Provision of accessory undercuts » Creating favourable undercuts • Modified denture construction procedure e. immediate denture where construction of the denture proceeds surgery . • Ridge augmentation • It is aimed at : • Increase in the ridge height and width providing a large denture bearing area . – Tri calcium phoshpate . • Protection of neuro vascular bundles • Restoration of proper maxillomandibular arch relationship. • Ridge augmentation has been tried with: – Bone transplants – Autogenous and homogenous cartilage – Hydroxyapatite porous replamine form – Acrylic implants. • IMPLANTS . • ADVANCED RRR: Surgical management ( IJP 1993) • With introduction of osseointegration by Branemark reconsrtuction of advanced RRR has become a successful procedure • The various problems associated with RRR and stability of removable soft tissue borne dentures have aroused interest in dental implantology to provide stable mechanical support to the dental prosthesis. . retention and phonetics. Height of alveolar bone is found to be maintained as long as the implant remains healthy. Maintenance of alveolar bone Maintenance of occlusal vertical dimension.• • • • IMPLANT SUPPORTED PROSTHESIS. • Regained proprioception. • Increased stability. . • Improved psychological health. • Maintenance of structure and function of muscles of mastication and facial expression. • Immune to caries. . • Efficiency to take up stress and strain. • Overall volume of bone is maintained. • There is 20 fold decrease in the loss of structure with implants when compared with resorption that occurs with removable prosthesis. . but the exact processes involved are poorly understood.• CONCLUSION : • The etiology of residual ridge resorption is a subtle combination of local and systemic factors. • There is no reliable clinical measurement. which might predict the future rate of alveolar ridge resorption in a particular edentulous patient. But as with natural teeth.• The best possible method is to preserve as many teeth or roots. • The use of endosseous implants to support fixed or removable prostheses has been shown to preserve adjacent remaining alveolar bone. followed by over-dentures which may act as effective means of preserving adjacent alveolar bone. . implants are not immune to bone loss. as possible.