Biomechanics of edentulous state / orthodontic teeth

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Biomechanics of edentulous state / orthodontic teeth

  1. 1. BIOMECHANICSBIOMECHANICS OFOF EDENTULOUS STATEEDENTULOUS STATE INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com
  2. 2. contents  Introduction  Mechanism of support Natural dentition Complete denture  Function and Para function  Morphologic changes in Face height TMJ Cosmetic changes  Psychological changes  Adaptive response  Summary  Bibliography www.indiandentalacademy.comwww.indiandentalacademy.com
  3. 3. INTRODUCTIONINTRODUCTION The edentulous state represents aThe edentulous state represents a compromise in the integrity of masticatorycompromise in the integrity of masticatory system. It is frequently accompanied bysystem. It is frequently accompanied by adverse function and cosmetic problemsadverse function and cosmetic problems which are varyingly perceived by affectedwhich are varyingly perceived by affected patient.patient. Perception of edentulous state may rangePerception of edentulous state may range from feelings of inconvenience to feelings offrom feelings of inconvenience to feelings of severe handicap as some regard total toothsevere handicap as some regard total tooth loss as equivalent to loss of a body part.loss as equivalent to loss of a body part.www.indiandentalacademy.comwww.indiandentalacademy.com
  4. 4. DEFINITIONSDEFINITIONS BIOMECHANICS:BIOMECHANICS:  The application of mechanical laws to livingThe application of mechanical laws to living structures, specifically the locomotor systemsstructures, specifically the locomotor systems of the body.of the body. The study of biology from the functional viewThe study of biology from the functional view point.point. An application of principles of engineeringAn application of principles of engineering design as implemented in living organisms.design as implemented in living organisms. www.indiandentalacademy.comwww.indiandentalacademy.com
  5. 5. DENTALDENTAL BIOMECHANICS:BIOMECHANICS: The relationship between the biologicThe relationship between the biologic behavior of oral structures and the physicalbehavior of oral structures and the physical influence of a dental restoration.influence of a dental restoration. www.indiandentalacademy.comwww.indiandentalacademy.com
  6. 6.  The treatment of edentulous state present aThe treatment of edentulous state present a range of biomechanical problems that involverange of biomechanical problems that involve individual tolerances and perceptions.individual tolerances and perceptions. www.indiandentalacademy.comwww.indiandentalacademy.com
  7. 7. The clinical implications of the biomechanicalThe clinical implications of the biomechanical differences can be considered under thedifferences can be considered under the following:following: 1. Modifications in area of support.1. Modifications in area of support. 2.Functional and Para functional2.Functional and Para functional considerations.considerations. 3. Changes in morphologic face height.3. Changes in morphologic face height. 4. Cosmetic changes.4. Cosmetic changes. 5. Adaptive responses.5. Adaptive responses. www.indiandentalacademy.comwww.indiandentalacademy.com
  8. 8. MODIFICATIONS IN AREA OFMODIFICATIONS IN AREA OF SUPPORTSUPPORT DefinitionsDefinitions Mechanism of tooth supportMechanism of tooth support Mechanism of denture supportMechanism of denture support www.indiandentalacademy.comwww.indiandentalacademy.com
  9. 9. DEFINITIONSDEFINITIONS SUPPORT:SUPPORT: To hold up ,serve as a foundation, or propTo hold up ,serve as a foundation, or prop for.for. The foundation area on which a dentalThe foundation area on which a dental prosthesis rests. With respect to dentalprosthesis rests. With respect to dental prostheses, the resistance to displacementprostheses, the resistance to displacement away from the basal tissue or underlyingaway from the basal tissue or underlying structures.structures. www.indiandentalacademy.comwww.indiandentalacademy.com
  10. 10. SUPPORTING AREA:SUPPORTING AREA: The surface of the mouth available forThe surface of the mouth available for support of a denture[ GPT1].support of a denture[ GPT1]. Those areas of maxillary and mandibularThose areas of maxillary and mandibular edentulous ridges that are considered bestedentulous ridges that are considered best suited to carry the forces of masticationsuited to carry the forces of mastication when the dentures are in function. [ GPT 1].when the dentures are in function. [ GPT 1]. www.indiandentalacademy.comwww.indiandentalacademy.com
  11. 11. MECHANISM OF TOOTHMECHANISM OF TOOTH SUPPORTSUPPORT The whole masticatory apparatus isThe whole masticatory apparatus is involved in the process of trituration ofinvolved in the process of trituration of food.the direct responsibility of this tasksfood.the direct responsibility of this tasks falls on the teeth and their supportingfalls on the teeth and their supporting structures .structures . The attachment of teeth in their sockets isThe attachment of teeth in their sockets is but one of the many important modificationsbut one of the many important modifications that took place during the period when thethat took place during the period when the earliest mammals were evolving from theearliest mammals were evolving from the reptilians predecessors.reptilians predecessors.www.indiandentalacademy.comwww.indiandentalacademy.com
  12. 12. Teeth functions properly only if adequatelyTeeth functions properly only if adequately supported .supported . Periodontium is the connective tissuePeriodontium is the connective tissue support mechanism for teeth .support mechanism for teeth . It is composed of hard connective tissueIt is composed of hard connective tissue [cementum and bone] soft connective tissue[[cementum and bone] soft connective tissue[ lamina propria of the gingiva and periodontallamina propria of the gingiva and periodontal ligament].ligament]. www.indiandentalacademy.comwww.indiandentalacademy.com
  13. 13. Periodontium is regarded as a functional unit and is attached to dentin by cementum and to the jaw bone by the alveolar processes. The periodontal ligament and lamina propria maintains the continuity between these hard and soft tissue components. www.indiandentalacademy.comwww.indiandentalacademy.com
  14. 14. PERIODONTIUMPERIODONTIUM www.indiandentalacademy.comwww.indiandentalacademy.com
  15. 15. PERIODONTAL LIGAMENTPERIODONTAL LIGAMENT The periodontal ligament is the connectiveThe periodontal ligament is the connective tissue that surrounds the root and connectstissue that surrounds the root and connects it to the bone .it to the bone . It is composed of:It is composed of:  Fibers.Fibers.  Cellular elements.Cellular elements.  Ground substance.Ground substance. www.indiandentalacademy.comwww.indiandentalacademy.com
  16. 16. FIBERSFIBERS Principal fibers :Principal fibers : Collagenous.Collagenous. Arranged in bundles.Arranged in bundles. Follow wavy course.Follow wavy course. Insert into cementum and bone [sharpey’sInsert into cementum and bone [sharpey’s fibers].fibers]. www.indiandentalacademy.comwww.indiandentalacademy.com
  17. 17. Principal fibers are arranged in six groups thatPrincipal fibers are arranged in six groups that develop sequentially in the developing rootdevelop sequentially in the developing root 1. Transseptal group1. Transseptal group 2. Alveolar crestal group2. Alveolar crestal group 3. Horizontal group3. Horizontal group 4. Oblique group4. Oblique group 5. Apical group5. Apical group 6. Inter radicular group6. Inter radicular group www.indiandentalacademy.comwww.indiandentalacademy.com
  18. 18. Periodontal ligament fibersPeriodontal ligament fibers www.indiandentalacademy.comwww.indiandentalacademy.com
  19. 19. CELLULAR ELEMENTSCELLULAR ELEMENTS Types Of Cells:Types Of Cells: 1.Connective tissue cells- fibroblasts,1.Connective tissue cells- fibroblasts, cementoblasts, and osteoblasts.cementoblasts, and osteoblasts. 2. Epithelial cell rests- remnants of hertwigs2. Epithelial cell rests- remnants of hertwigs root sheath[ cell rests of malassez].root sheath[ cell rests of malassez]. 3.Immune system cells-neutrophils,3.Immune system cells-neutrophils, lymphocytes, macrophages, mast cells andlymphocytes, macrophages, mast cells and eosinophils.eosinophils. www.indiandentalacademy.comwww.indiandentalacademy.com
  20. 20. GROUND SUBSTANCEGROUND SUBSTANCE Glycosaminoglycans-hyaluronic acid andGlycosaminoglycans-hyaluronic acid and proteoglycans.proteoglycans.  Glycoprotiens-fibronectin and laminin. 70% isGlycoprotiens-fibronectin and laminin. 70% is composed of water.composed of water. The ground substances fills the spacesThe ground substances fills the spaces between fibers and cells.between fibers and cells. Cementicles which may be free or attached toCementicles which may be free or attached to root surfaces may be present.root surfaces may be present. www.indiandentalacademy.comwww.indiandentalacademy.com
  21. 21. FUNCTIONSFUNCTIONS Physical function.Physical function. Formative and remodelling function.Formative and remodelling function. Nutritional function.Nutritional function. sensory function.sensory function. www.indiandentalacademy.comwww.indiandentalacademy.com
  22. 22. 1.Resistance to impact of occlusal forces1.Resistance to impact of occlusal forces [shock absorption]. Two theories relative to[shock absorption]. Two theories relative to mechanism of tooth support have beenmechanism of tooth support have been considered.considered. a.Tentional theory:a.Tentional theory: According to this theoryAccording to this theory when force is applied to the crown principalwhen force is applied to the crown principal fibers first unfold and straightened and thenfibers first unfold and straightened and then transmit the forces to alveolar bone causingtransmit the forces to alveolar bone causing elastic deformation of the bony socket. Whenelastic deformation of the bony socket. When alveolar bone has reached its limit load isalveolar bone has reached its limit load is transmitted to basal bone .transmitted to basal bone . PHYSICAL FUNCTIONPHYSICAL FUNCTION www.indiandentalacademy.comwww.indiandentalacademy.com
  23. 23.  b. Viscoelastic system theory-b. Viscoelastic system theory- According to thisAccording to this theory fluids move out of the PDL into marrowtheory fluids move out of the PDL into marrow spaces through foramina when forces arespaces through foramina when forces are applied. The fibers slack and tighten. Arteryapplied. The fibers slack and tighten. Artery stenosis causes back pressure and ballooningstenosis causes back pressure and ballooning of vessels to replenish the tissue fluids.of vessels to replenish the tissue fluids. www.indiandentalacademy.comwww.indiandentalacademy.com
  24. 24. 2. transmission of occlusal forces to bone2. transmission of occlusal forces to bone The principal fibers are arranged similar toThe principal fibers are arranged similar to suspension bridge or hammock.suspension bridge or hammock.  Axial forces – oblique fibers.Axial forces – oblique fibers.  Horizontal forces-primary tooth movementHorizontal forces-primary tooth movement within the confines of PDL and secondary toothwithin the confines of PDL and secondary tooth movement by displacement of facial and lingualmovement by displacement of facial and lingual bony plates.bony plates.  Axis of rotation - PDL is shaped as an hourAxis of rotation - PDL is shaped as an hour glass and thinnest at the axis of rotation.glass and thinnest at the axis of rotation. www.indiandentalacademy.comwww.indiandentalacademy.com
  25. 25. www.indiandentalacademy.comwww.indiandentalacademy.com
  26. 26. FORMATIVE AND REMODELLINGFORMATIVE AND REMODELLING The cells of the PDL are responsible forThe cells of the PDL are responsible for continues remodelling of bone and cementumcontinues remodelling of bone and cementum which occur to accommodatewhich occur to accommodate Physiological tooth movement.Physiological tooth movement. Response to occlusal forces.Response to occlusal forces. Repair of injuries.Repair of injuries. www.indiandentalacademy.comwww.indiandentalacademy.com
  27. 27. NUTRITION AND SENSORYNUTRITION AND SENSORY FUNCTIONFUNCTION The PDL supplies nutrition to laminaThe PDL supplies nutrition to lamina propria, bone and cementum .propria, bone and cementum . Nerve bundles pass into PDL divide intoNerve bundles pass into PDL divide into single myelinated fibers, loose theresingle myelinated fibers, loose there myelin sheaths and end in one of the fourmyelin sheaths and end in one of the four types of neural termination.types of neural termination. 1.Free endings-tree like and carry pain1.Free endings-tree like and carry pain sensation.sensation. 2.Ruffini’s corpuscles- mechanoreceptors2.Ruffini’s corpuscles- mechanoreceptors [apical area][apical area] www.indiandentalacademy.comwww.indiandentalacademy.com
  28. 28. 3.Meissnerscorpuscles-mechanoreceptors3.Meissnerscorpuscles-mechanoreceptors [midroot area].[midroot area]. 4.Spindles-pressure and vibration endings4.Spindles-pressure and vibration endings [apical area].[apical area]. www.indiandentalacademy.comwww.indiandentalacademy.com
  29. 29. Nerve corpusclesNerve corpuscles www.indiandentalacademy.comwww.indiandentalacademy.com
  30. 30. As soon as the teeth erupt into the oral cavityAs soon as the teeth erupt into the oral cavity and occlusal contact is established, the nonand occlusal contact is established, the non functional orientation of PDL fibers changesfunctional orientation of PDL fibers changes into functional arrangement.into functional arrangement. The occlusal forces exerted by teeth areThe occlusal forces exerted by teeth are controlled by neuromuscular mechanism ofcontrolled by neuromuscular mechanism of masticatory systems.masticatory systems. The propioceptors in the PDL muscles andThe propioceptors in the PDL muscles and TMJ have specific memory patternsTMJ have specific memory patterns [engrams] which guide the jaw to the correct[engrams] which guide the jaw to the correct closing pattern.closing pattern. www.indiandentalacademy.comwww.indiandentalacademy.com
  31. 31. FORCES ACTING ON THE TEETHFORCES ACTING ON THE TEETH The greatest forces acting on teeth areThe greatest forces acting on teeth are produced during mastication deglutition, areproduced during mastication deglutition, are essentially vertical in direction.essentially vertical in direction. Loads of lower order but of longer durationLoads of lower order but of longer duration are produced through out the day by tongueare produced through out the day by tongue and perioral musculature .these forces areand perioral musculature .these forces are predominantly in horizontal direction.predominantly in horizontal direction. www.indiandentalacademy.comwww.indiandentalacademy.com
  32. 32. Graf [1969] calculated the total time duringGraf [1969] calculated the total time during which teeth are subjected to functionalwhich teeth are subjected to functional forces . He concluded that this total timeforces . He concluded that this total time and range seemed to be well withinand range seemed to be well within tolerance level of healthy periodontaltolerance level of healthy periodontal tissues.tissues. www.indiandentalacademy.comwww.indiandentalacademy.com
  33. 33. Actual chewingActual chewing time per mealtime per meal 450 sec450 sec Four meals per dayFour meals per day 1800 sec1800 sec Each second 1Each second 1 chewing strokechewing stroke 1800 stroke1800 stroke Duration of eachDuration of each strokestroke 0.3 sec0.3 sec Total chewingTotal chewing forcesforces 540 sec= 9 min540 sec= 9 min CHEWINGCHEWING www.indiandentalacademy.comwww.indiandentalacademy.com
  34. 34. SWALLOWINGSWALLOWING MealsMeals Duration of one deglutitionDuration of one deglutition movementmovement 1 sec1 sec During chewing 3* perDuring chewing 3* per min1/3 of movements withmin1/3 of movements with occlusal force onlyocclusal force only 30 sec 0.5 min30 sec 0.5 min Between mealsBetween meals Day time -25 per hour [16Day time -25 per hour [16 hours]hours] 400 sec, 6.6400 sec, 6.6 minmin Sleep -10 per hour[8 hours]Sleep -10 per hour[8 hours] 80 sec , 1.380 sec , 1.3 minminwww.indiandentalacademy.comwww.indiandentalacademy.com
  35. 35. Total 1050 seconds= 17.5 minTotal 1050 seconds= 17.5 min www.indiandentalacademy.comwww.indiandentalacademy.com
  36. 36. MECHANISM OF COMPLETEMECHANISM OF COMPLETE DENTURE SUPPORTDENTURE SUPPORT The basic problem in treatment of edentulousThe basic problem in treatment of edentulous patients lies in the nature of differencepatients lies in the nature of difference between the ways natural and their artificialbetween the ways natural and their artificial replacements are attached to supportingreplacements are attached to supporting bone.bone. The complete dentures are not a substituteThe complete dentures are not a substitute for natural teeth, but only a prosthetic solutionfor natural teeth, but only a prosthetic solution for no teeth.for no teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  37. 37. The factors which differ in supporting theThe factors which differ in supporting the natural teeth and complete dentures are:natural teeth and complete dentures are: 1. Nature of support.1. Nature of support. 2. Area of support.2. Area of support. 3. Masticatory loads.3. Masticatory loads. www.indiandentalacademy.comwww.indiandentalacademy.com
  38. 38.  PDLPDL  Edentulous ridgeEdentulous ridge www.indiandentalacademy.comwww.indiandentalacademy.com
  39. 39. NATURE OF SUPPORTNATURE OF SUPPORT The unsuitability of tissue supporting completeThe unsuitability of tissue supporting complete denture for load bearing function must bedenture for load bearing function must be immediately recognized.immediately recognized. In normal function in dentulous state light loadsIn normal function in dentulous state light loads are placed on the mucous membrane.are placed on the mucous membrane. With complete dentures the mucousWith complete dentures the mucous membrane is forced to serve the samemembrane is forced to serve the same purpose as PDL, that provides support forpurpose as PDL, that provides support for natural teeth.natural teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  40. 40. ORAL MUCOSAORAL MUCOSA The oral mucous membrane is the lining ofThe oral mucous membrane is the lining of the oral cavity. At the lips it is continuousthe oral cavity. At the lips it is continuous with the skin & at the pharynx continuouswith the skin & at the pharynx continuous with the intestinal mucosa .Its structurewith the intestinal mucosa .Its structure varies in an apparent adaptation to functionvaries in an apparent adaptation to function in different areas of the oral cavity.in different areas of the oral cavity. www.indiandentalacademy.comwww.indiandentalacademy.com
  41. 41. CLASSIFICATIONCLASSIFICATION  BASED ON THE FUNCTIONAL CRITERIABASED ON THE FUNCTIONAL CRITERIA  Masticatory mucosa.Masticatory mucosa.  Lining or reflecting mucosa.Lining or reflecting mucosa.  Specialized mucosa.Specialized mucosa.  BASED HISTOLOGICALLY ON KERATINIZATIONBASED HISTOLOGICALLY ON KERATINIZATION  Keratinized mucosa.Keratinized mucosa.  Non keratinized mucosa.Non keratinized mucosa. www.indiandentalacademy.comwww.indiandentalacademy.com
  42. 42. Oral mucous membraneOral mucous membrane www.indiandentalacademy.comwww.indiandentalacademy.com
  43. 43. MASTICATORY MUCOSAMASTICATORY MUCOSA Seen on the gingiva and hard palateSeen on the gingiva and hard palate  Gingiva –Gingiva – 1. Epithelium is ortho or Para keratinized1. Epithelium is ortho or Para keratinized with stippling, lamina propria shows longwith stippling, lamina propria shows long narrow papillae with dense collagenousnarrow papillae with dense collagenous connective tissue .connective tissue . 2. Sub mucosa - is not distinct as mucosa2. Sub mucosa - is not distinct as mucosa attaches by collagen fibers into cementumattaches by collagen fibers into cementum and bone(mucoperiostium).and bone(mucoperiostium). www.indiandentalacademy.comwww.indiandentalacademy.com
  44. 44. HARD PALATEHARD PALATE EpitheliumEpithelium – orthokeratinized, Parakeratinized– orthokeratinized, Parakeratinized in parts with transverse palatal ridges into C.T.in parts with transverse palatal ridges into C.T. Lamina propriaLamina propria – long papillae with dense– long papillae with dense collagenous tissue especially under rugae.collagenous tissue especially under rugae. Sub mucosaSub mucosa – dense collagenous tissue– dense collagenous tissue attaching the mucosa to periosteumattaching the mucosa to periosteum (mucoperiostium) .anteriorly adipose tissue and(mucoperiostium) .anteriorly adipose tissue and posteriorly minor salivary glands are packedposteriorly minor salivary glands are packed into the C.T.into the C.T. www.indiandentalacademy.comwww.indiandentalacademy.com
  45. 45. LINING MUCOSALINING MUCOSA It is found on the lip, cheek, vestibular fornix,It is found on the lip, cheek, vestibular fornix, ventral surface of the tongue, floor of theventral surface of the tongue, floor of the mouth and soft palate. It is nonkeratinizedmouth and soft palate. It is nonkeratinized stratified squamous variety.stratified squamous variety. www.indiandentalacademy.comwww.indiandentalacademy.com
  46. 46. LIPSLIPS Vermilion border – thin ortho or ParaVermilion border – thin ortho or Para keratinized epithelium.keratinized epithelium. Lamina propria – has numerous long narrowLamina propria – has numerous long narrow papillae with capillary loops close to thepapillae with capillary loops close to the epithelium .epithelium . Submucosa – is firmly attached to unde4rSubmucosa – is firmly attached to unde4r lying muscle ;some sebaceous glands in thelying muscle ;some sebaceous glands in the vermilion border. Intermediate zone showsvermilion border. Intermediate zone shows minor salivary glands & fatminor salivary glands & fat www.indiandentalacademy.comwww.indiandentalacademy.com
  47. 47. LABIAL AND BUCCAL MUCOSALABIAL AND BUCCAL MUCOSA Epithelium is very thick. Lamina propria –hasEpithelium is very thick. Lamina propria –has long slender papillae ,dense fibrous C.Tlong slender papillae ,dense fibrous C.T containing elastic and collagen fibers.containing elastic and collagen fibers. Submucosa is firmly attached to underlyingSubmucosa is firmly attached to underlying muscle. Few minor salivary glands andmuscle. Few minor salivary glands and sebaceous glands are seen. it prevents thesebaceous glands are seen. it prevents the mucosa from folding. .mucosa from folding. . www.indiandentalacademy.comwww.indiandentalacademy.com
  48. 48. FLOOR OF THE MOUTHFLOOR OF THE MOUTH Epithelium very thin nonkeratinized variety.Epithelium very thin nonkeratinized variety. Lamina propria –has short papillae, elasticLamina propria –has short papillae, elastic fibers & capillary anastomoses .allows forfibers & capillary anastomoses .allows for tongue movements.tongue movements. Submucosa – has loose C.T & minor salivarySubmucosa – has loose C.T & minor salivary glands.glands. www.indiandentalacademy.comwww.indiandentalacademy.com
  49. 49. VENTRAL SURFACE OF TONGUEVENTRAL SURFACE OF TONGUE Epithelium – thin nonkeratinized variety.Epithelium – thin nonkeratinized variety. Lamina propria – thin with short papillaeLamina propria – thin with short papillae elastic fibers & minor salivary glandselastic fibers & minor salivary glands .papillary network in sub papillary layer..papillary network in sub papillary layer. Submucosa – no distinct layer ,mucosa isSubmucosa – no distinct layer ,mucosa is bound to tongue musculature .bound to tongue musculature . www.indiandentalacademy.comwww.indiandentalacademy.com
  50. 50. SOFT PALATESOFT PALATE Epithelium – thick non keratinized with tasteEpithelium – thick non keratinized with taste buds .buds . Lamina propria –thick with numerous shortLamina propria –thick with numerous short papillae; elastic fibers forming an elasticpapillae; elastic fibers forming an elastic lamina.lamina. Submucosa –diffuse containing numerousSubmucosa –diffuse containing numerous minor salivary glands .minor salivary glands . www.indiandentalacademy.comwww.indiandentalacademy.com
  51. 51. ALVEOLAR MUCOSAALVEOLAR MUCOSA Epithelium -thin non keratinized variety.Epithelium -thin non keratinized variety. Lamina propria –short papillae C.T showsLamina propria –short papillae C.T shows many elastic fibers & capillary loops close tomany elastic fibers & capillary loops close to surface.surface. Submucosa –loose C.T containing elasticSubmucosa –loose C.T containing elastic fibers attaching it to periosteum of alveolarfibers attaching it to periosteum of alveolar bone & minor salivary glands.bone & minor salivary glands. www.indiandentalacademy.comwww.indiandentalacademy.com
  52. 52. SPECIALIZED MUCOSASPECIALIZED MUCOSA Dorsal surface of the tongue is divided by V –Dorsal surface of the tongue is divided by V – shaped sulcus terminalis into 2 parts.shaped sulcus terminalis into 2 parts. Anterior 2/3 [papillary] portion.Anterior 2/3 [papillary] portion. Posterior 1/3 [lymphoid] portion.Posterior 1/3 [lymphoid] portion. www.indiandentalacademy.comwww.indiandentalacademy.com
  53. 53. Anterior 2/3 of tongue shows “Anterior 2/3 of tongue shows “SS” cone shaped” cone shaped filliform papillae which gives velvettefilliform papillae which gives velvette appearance. Interspersed between them areappearance. Interspersed between them are mushroom shaped fungi form papillae withmushroom shaped fungi form papillae with taste buds. In front of the sulcus are 8 to 10taste buds. In front of the sulcus are 8 to 10 circumvalate papillae .circumvalate papillae . They have a trough into which von ebnersThey have a trough into which von ebners glands open & have taste buds. On the lateralglands open & have taste buds. On the lateral border of the posterior part of the tongue areborder of the posterior part of the tongue are parallel clefts of varying length they areparallel clefts of varying length they are vestige of large foliate papillae ,they containvestige of large foliate papillae ,they contain taste buds.taste buds. www.indiandentalacademy.comwww.indiandentalacademy.com
  54. 54. EPITHELIUMEPITHELIUM Oral epithelium is of stratified squamousOral epithelium is of stratified squamous variety. It may be keratinized or nonvariety. It may be keratinized or non keratinized. Cells with ultimately keratinizekeratinized. Cells with ultimately keratinize are called keratocytes or keratinocytes.are called keratocytes or keratinocytes. Keratinizing oral epithelium has 4 cellKeratinizing oral epithelium has 4 cell layerslayers.. Stratum basale.Stratum basale. Stratum spinosum.Stratum spinosum. Stratum granulosum.Stratum granulosum. Stratum corneum.Stratum corneum. www.indiandentalacademy.comwww.indiandentalacademy.com
  55. 55. LAMINA PROPRIALAMINA PROPRIA For descriptive reasons it is divided into 2 partsFor descriptive reasons it is divided into 2 parts Papillary portion & Reticular portion.Papillary portion & Reticular portion. The lamina propria contains fine immatureThe lamina propria contains fine immature collagen fibers termed reticular fibers. Itcollagen fibers termed reticular fibers. It contains, fibroblasts,histocytes, collagen fibercontains, fibroblasts,histocytes, collagen fiber bundle & vasculature. The interlockingbundle & vasculature. The interlocking arrangement of CT papillae & epithelial ridgesarrangement of CT papillae & epithelial ridges & even finer undulation & projection found at& even finer undulation & projection found at the base of each epithelial cell increases thethe base of each epithelial cell increases the area of contact between epithelium & CT.area of contact between epithelium & CT.www.indiandentalacademy.comwww.indiandentalacademy.com
  56. 56. SUBMUCOSASUBMUCOSA It attaches the overlying mucosa toIt attaches the overlying mucosa to periosteum. Its composition varies inperiosteum. Its composition varies in different areas of the oral mucosa. Itdifferent areas of the oral mucosa. It contains glands, adipose tissue musclescontains glands, adipose tissue muscles ,blood vessels, nerves & lymph vessels.,blood vessels, nerves & lymph vessels. www.indiandentalacademy.comwww.indiandentalacademy.com
  57. 57. RESIDUAL RIDGERESIDUAL RIDGE When the alveolar process is madeWhen the alveolar process is made edentulous,by loss of teeth,the alveoli thatedentulous,by loss of teeth,the alveoli that contained the roots of the teeth fill in withcontained the roots of the teeth fill in with new bone.new bone. This alveolar process becomes the residualThis alveolar process becomes the residual ridge ,which is the foundation for dentures.ridge ,which is the foundation for dentures. Residual ridge is that bone of the alveolarResidual ridge is that bone of the alveolar process that remains after the teeth are lostprocess that remains after the teeth are lost Residual ridge consists of denture bearingResidual ridge consists of denture bearing mucosa ,the submucosa ,periosteum andmucosa ,the submucosa ,periosteum and underlying residual alveolar bone.underlying residual alveolar bone.www.indiandentalacademy.comwww.indiandentalacademy.com
  58. 58.  Alveolar ridge vary greatly in size andAlveolar ridge vary greatly in size and shape and their ultimate form is dependentshape and their ultimate form is dependent on following factors.on following factors. 1.Developmental structure.1.Developmental structure. 2.Size of natural teeth.2.Size of natural teeth. 3.Amount of bone lost prior to extraction-3.Amount of bone lost prior to extraction- Periodontitis.Periodontitis. 4.Amount of alveolar process removed4.Amount of alveolar process removed during extraction.during extraction. 5.Rate and degree of resorption.5.Rate and degree of resorption. 6.Effect of previous dentures.6.Effect of previous dentures. www.indiandentalacademy.comwww.indiandentalacademy.com
  59. 59. RR may be said to have 2 forms:RR may be said to have 2 forms:  Anatomic formAnatomic form – surface contour of ridge– surface contour of ridge when it is not supporting an occlusal load.when it is not supporting an occlusal load. Functional formFunctional form - surface contour of ridge- surface contour of ridge when it is supporting an occlusal load.when it is supporting an occlusal load. www.indiandentalacademy.comwww.indiandentalacademy.com
  60. 60. When the alveolar process is madeWhen the alveolar process is made edentulous,by loss of teeth, the alveoli thatedentulous,by loss of teeth, the alveoli that contained the roots of the teeth fill in with newcontained the roots of the teeth fill in with new bone.bone. This alveolar process becomes the residualThis alveolar process becomes the residual ridge , which is the foundation for dentures.ridge , which is the foundation for dentures. Residual ridge is that bone of the alveolarResidual ridge is that bone of the alveolar process that remains after the teeth are lost.process that remains after the teeth are lost. Residual ridge consists of denture bearingResidual ridge consists of denture bearing mucosa ,the submucosa ,periosteum andmucosa ,the submucosa ,periosteum and underlying residual alveolar bone.underlying residual alveolar bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  61. 61. Residual ridgeResidual ridge www.indiandentalacademy.comwww.indiandentalacademy.com
  62. 62. CONTOUR & QUALITY OFCONTOUR & QUALITY OF RESIDUAL RIDGERESIDUAL RIDGE Ideal residual ridge is to support a dentureIdeal residual ridge is to support a denture base would consist of cortical bone thatbase would consist of cortical bone that covers relatively dense cancellous bonecovers relatively dense cancellous bone with a broad rounded crest with high verticalwith a broad rounded crest with high vertical slopes & covered by firm dense fibrousslopes & covered by firm dense fibrous connective tissue. such a residual ridgeconnective tissue. such a residual ridge would optimally support vertical &would optimally support vertical & horizontal stresses placed on it by denturehorizontal stresses placed on it by denture base.base. www.indiandentalacademy.comwww.indiandentalacademy.com
  63. 63. PATHOLOGY OF RESIDUALPATHOLOGY OF RESIDUAL RIDGE RESORPTIONRIDGE RESORPTION Gross Pathology.Gross Pathology. Microscopic pathology.Microscopic pathology. www.indiandentalacademy.comwww.indiandentalacademy.com
  64. 64. GROSS PATHOLOGYGROSS PATHOLOGY Reduction in the size of the bony ridge.Reduction in the size of the bony ridge. It is primarily a localized loss of boneIt is primarily a localized loss of bone structure.structure. In clinical examination, usually ,one canIn clinical examination, usually ,one can visualize the residual ridge form.however thisvisualize the residual ridge form.however this may be masked with redundant or inflamedmay be masked with redundant or inflamed soft tissue.soft tissue. This can be accurately determined byThis can be accurately determined by palpation.palpation. www.indiandentalacademy.comwww.indiandentalacademy.com
  65. 65. Lateral cephalometric radiographs provide theLateral cephalometric radiographs provide the most accurate method for determining themost accurate method for determining the amount of residual ridge and rate of RRR overamount of residual ridge and rate of RRR over a period of time.a period of time. Numerous longitudinal radiographic studiesNumerous longitudinal radiographic studies have provided excellent visualization of thehave provided excellent visualization of the gross patterns of bone loss.gross patterns of bone loss. Superimposition of portions of tracings ofSuperimposition of portions of tracings of lateral cephalograms has clearly shown thelateral cephalograms has clearly shown the gross reduction of bone in size and shapegross reduction of bone in size and shape that occurs on the external surface on thethat occurs on the external surface on the labial ,crestal and lingual aspects of residuallabial ,crestal and lingual aspects of residual ridge.ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  66. 66. www.indiandentalacademy.comwww.indiandentalacademy.com
  67. 67. Order – IOrder – I pre-extractionpre-extraction Order –IIOrder –II post-extractionpost-extraction Order –IIIOrder –III high well roundedhigh well rounded Order-IVOrder-IV knife edgeknife edge Order-VOrder-V low well roundedlow well rounded Order –VIOrder –VI depresseddepressed www.indiandentalacademy.comwww.indiandentalacademy.com
  68. 68. www.indiandentalacademy.comwww.indiandentalacademy.com
  69. 69. www.indiandentalacademy.comwww.indiandentalacademy.com
  70. 70. MICROSCOPIC PATHOLOGYMICROSCOPIC PATHOLOGY Studies have revealed evidence ofStudies have revealed evidence of osteoclastic activity on the external surfaceosteoclastic activity on the external surface of the crest of residual ridges, where visibleof the crest of residual ridges, where visible osteoclasts are seen.osteoclasts are seen. www.indiandentalacademy.comwww.indiandentalacademy.com
  71. 71. PATHOPHYSIOLOGY OFPATHOPHYSIOLOGY OF RESIDUAL RIDGERESIDUAL RIDGE RESORPTIONRESORPTION During growth ,bone formation exceedsDuring growth ,bone formation exceeds bone resorption.bone resorption. Osteoporosis- generalized disease ofOsteoporosis- generalized disease of bone ,where bone resorption exceeds bonebone ,where bone resorption exceeds bone formation.formation. RRR is a localized physiologic loss of bone.RRR is a localized physiologic loss of bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  72. 72. Physiologic process of internal bonePhysiologic process of internal bone remodelling goes on, even in the presence ofremodelling goes on, even in the presence of this pathologic external osteoclastic activitythis pathologic external osteoclastic activity that is responsible for the loss of so muchthat is responsible for the loss of so much bone substance.bone substance. Three types of endosteal bone on the crest ofThree types of endosteal bone on the crest of the residual ridge are;the residual ridge are; A well-rounded compact cortical layerA well-rounded compact cortical layer consisting of a whorled,convoluted type ofconsisting of a whorled,convoluted type of bone.bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  73. 73. A knife edge ridge that shows a lingual plateA knife edge ridge that shows a lingual plate of whorled convoluted bone & a labial plateof whorled convoluted bone & a labial plate of uninterrupted circumferential lamellae onof uninterrupted circumferential lamellae on its endosteal side.its endosteal side. A low depressed ridge that has no crestalA low depressed ridge that has no crestal cortical layer but only trabecular bone,cortical layer but only trabecular bone, which is actually medullary bone.which is actually medullary bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  74. 74. RRR is chronic, progressive, irreversible &RRR is chronic, progressive, irreversible & cumulative, usually RRR proceeds slowly overcumulative, usually RRR proceeds slowly over a long period of time flowing from one stagea long period of time flowing from one stage imperceptibly to the next.imperceptibly to the next. The patient with the most RRR in the earlyThe patient with the most RRR in the early post extraction period continued to have thepost extraction period continued to have the highest rate of RRR in the later stages.highest rate of RRR in the later stages. www.indiandentalacademy.comwww.indiandentalacademy.com
  75. 75. RATE OF RESORPTION OFRATE OF RESORPTION OF RESIDUAL ALVEOLAR RIDGESRESIDUAL ALVEOLAR RIDGES Depends on;Depends on; The size, shape, density of the alveolarThe size, shape, density of the alveolar ridge.ridge. The cellular activity of the osteoblast andThe cellular activity of the osteoblast and osteoclasts.osteoclasts. The duration, frequency and direction ofThe duration, frequency and direction of any previous occlusal forces to the bone.any previous occlusal forces to the bone. Forces generated from the presentForces generated from the present appliance.appliance. The patient’s resistance to these forces.The patient’s resistance to these forces.www.indiandentalacademy.comwww.indiandentalacademy.com
  76. 76. PATTERNS OF BONE LOSSPATTERNS OF BONE LOSS Tallgren in 1972,has stated that most ofTallgren in 1972,has stated that most of the bone loss occurs in the first year ofthe bone loss occurs in the first year of denture wearing and it is ten timesdenture wearing and it is ten times greater,than the loss seen in the followinggreater,than the loss seen in the following years.years. He also demonstrated four times moreHe also demonstrated four times more bone loss in the mandible,than in maxillabone loss in the mandible,than in maxilla over the years.over the years. (maxilla distributes the compressive forces(maxilla distributes the compressive forces over a wider surface area)over a wider surface area) www.indiandentalacademy.comwww.indiandentalacademy.com
  77. 77.  The direction of resorption in the maxilla differsThe direction of resorption in the maxilla differs from the mandibular bone resorption.from the mandibular bone resorption.  The usual resorption of the maxilla is on the buccalThe usual resorption of the maxilla is on the buccal and inferior portion of the alveolar ridge.the patternand inferior portion of the alveolar ridge.the pattern of edentulous bone loss results in upward andof edentulous bone loss results in upward and inward loss of structures.inward loss of structures.  In the anterior maxilla, there is less horizontalIn the anterior maxilla, there is less horizontal bone loss and posterior drift of the anterior crest isbone loss and posterior drift of the anterior crest is seen more than in the edentulous mandible.seen more than in the edentulous mandible. IIn then the posterior maxilla, there is inward drift of theposterior maxilla, there is inward drift of the posterior crest, the width of the maxilla is reduced.posterior crest, the width of the maxilla is reduced. www.indiandentalacademy.comwww.indiandentalacademy.com
  78. 78. www.indiandentalacademy.comwww.indiandentalacademy.com
  79. 79. Because of the progressive resorption overBecause of the progressive resorption over the years, the depth of the palatal vaultthe years, the depth of the palatal vault decreases and a very thin bone may bedecreases and a very thin bone may be present between the floor of the maxillarypresent between the floor of the maxillary sinus and the nasal cavity.sinus and the nasal cavity. The mandible resorbs downwards andThe mandible resorbs downwards and outwards causing rapid flattening of theoutwards causing rapid flattening of the ridge.ridge. Tallgren has estimated that the edentulousTallgren has estimated that the edentulous bone loss is up to 1mm per year,with thebone loss is up to 1mm per year,with the greatest loss occurring within 12-18 monthsgreatest loss occurring within 12-18 months after extractions.after extractions. www.indiandentalacademy.comwww.indiandentalacademy.com
  80. 80. www.indiandentalacademy.comwww.indiandentalacademy.com
  81. 81. Extractions of teeth done at different timesExtractions of teeth done at different times with long time gaps will exhibit irregular bonywith long time gaps will exhibit irregular bony ridge pattern.ridge pattern. Skeletal morphology has got definite role onSkeletal morphology has got definite role on the resorption pattern of the edentulousthe resorption pattern of the edentulous maxilla. People with long faces have moremaxilla. People with long faces have more alveolar height than those with short faces.alveolar height than those with short faces. Short face patients have greater biting force,Short face patients have greater biting force, therefore are predisposed to greater bonetherefore are predisposed to greater bone loss.loss. www.indiandentalacademy.comwww.indiandentalacademy.com
  82. 82. RESORPTIVE PATTERN OF THERESORPTIVE PATTERN OF THE EDENTULOUS RIDGEEDENTULOUS RIDGE (MERCIER1995)(MERCIER1995)  The ridge is wideThe ridge is wide enough at its crest toenough at its crest to accommodate theaccommodate the recently extracted teeth.recently extracted teeth.  The ridge becomes thinThe ridge becomes thin and pointed.and pointed.  The pointed ridgeThe pointed ridge flattens to the level offlattens to the level of basal bone.basal bone.  The flattened ridgeThe flattened ridge becomes concave as thebecomes concave as the basal bone resorbs.basal bone resorbs. Type I –minor ridgeType I –minor ridge modellingmodelling Type II –sharpType II –sharp atrophic residualatrophic residual ridgeridge Type III –basalType III –basal bone ridgebone ridge Type IV –basalType IV –basal bone resorptionbone resorption www.indiandentalacademy.comwww.indiandentalacademy.com
  83. 83. ETIOLOGY OF RRRETIOLOGY OF RRR RRR is directly proportional to AnatomicRRR is directly proportional to Anatomic factors -It varies with the quality,quantityfactors -It varies with the quality,quantity and density of bone of residual ridges.and density of bone of residual ridges. RRR varies directly with certain systemic orRRR varies directly with certain systemic or localized bone resorption factors andlocalized bone resorption factors and inversely with bone formation factors.inversely with bone formation factors. www.indiandentalacademy.comwww.indiandentalacademy.com
  84. 84. Local bone resorbing factors –include localLocal bone resorbing factors –include local biochemical factors, such as endotoxin,biochemical factors, such as endotoxin, osteoclast activating factor (OAF),osteoclast activating factor (OAF), prostaglandin's, human gingival boneprostaglandin's, human gingival bone resorption stimulating factor, heparinresorption stimulating factor, heparin (which is a cofactor in bone resorption)(which is a cofactor in bone resorption) trauma (ill-fitting denture) resultingtrauma (ill-fitting denture) resulting increased or decreased vascularity andincreased or decreased vascularity and changes in oxygen tension.changes in oxygen tension. www.indiandentalacademy.comwww.indiandentalacademy.com
  85. 85. Systemic factorsSystemic factors  Some individuals may already be in aSome individuals may already be in a negative bone balance owing to some formnegative bone balance owing to some form of osteoporosis and may therefore be moreof osteoporosis and may therefore be more vulnerable to unfavorable local factors.vulnerable to unfavorable local factors. www.indiandentalacademy.comwww.indiandentalacademy.com
  86. 86. MECHANICAL FACTORSMECHANICAL FACTORS Some postulate that RRR- ‘disuse atrophy’Some postulate that RRR- ‘disuse atrophy’ others postulate that RRR is an ‘abuse’others postulate that RRR is an ‘abuse’ bone resorption due to excessive forcesbone resorption due to excessive forces transmitted through dentures.transmitted through dentures.  The fact is that with or without denturesThe fact is that with or without dentures some patients have little or no RRR & somesome patients have little or no RRR & some have severe RRR.have severe RRR. Force is a co-factor in RRR can beForce is a co-factor in RRR can be expressed asexpressed as RRR is directly proportional to force.RRR is directly proportional to force. www.indiandentalacademy.comwww.indiandentalacademy.com
  87. 87. Design of dentures is to reduce the amount ofDesign of dentures is to reduce the amount of force to the ridge & thereby to reduce RRR.force to the ridge & thereby to reduce RRR. These prosthetic factors include;These prosthetic factors include; Broad-area coverage.Broad-area coverage. Decreased number of dental units.Decreased number of dental units. Decreased buccolingual width of teeth.Decreased buccolingual width of teeth. Improved tooth form.Improved tooth form. Avoidance of inclined planes.Avoidance of inclined planes. Centralization of occlusal contacts.Centralization of occlusal contacts. www.indiandentalacademy.comwww.indiandentalacademy.com
  88. 88. FORMULA RELATING TO RRRFORMULA RELATING TO RRR  RRRRRR anatomic factors +anatomic factors + Bone resorption factorsBone resorption factors Bone formation factorsBone formation factors Force factorsForce factors ++ Damping effect factorsDamping effect factors www.indiandentalacademy.comwww.indiandentalacademy.com
  89. 89. CLINICAL APPLICATIONCLINICAL APPLICATION Consequences of residual ridgeConsequences of residual ridge resorption.resorption. Apparent loss of sulcus width & depth,withApparent loss of sulcus width & depth,with displacement of the muscle attachment closerdisplacement of the muscle attachment closer to the crest of the residual ridge.to the crest of the residual ridge. Loss of the vertical dimension of occlusion.Loss of the vertical dimension of occlusion. Reduction of the lower face height.Reduction of the lower face height. www.indiandentalacademy.comwww.indiandentalacademy.com
  90. 90. www.indiandentalacademy.comwww.indiandentalacademy.com
  91. 91. www.indiandentalacademy.comwww.indiandentalacademy.com
  92. 92. CONTOUR & QUALITY OFCONTOUR & QUALITY OF RESIDUAL RIDGERESIDUAL RIDGE Ideal residual ridge is to support a dentureIdeal residual ridge is to support a denture base would consist of cortical bone thatbase would consist of cortical bone that covers relatively dense cancellous bonecovers relatively dense cancellous bone with a broad rounded crest with high verticalwith a broad rounded crest with high vertical slopes & covered by firm dense fibrousslopes & covered by firm dense fibrous connective tissue. such a residual ridgeconnective tissue. such a residual ridge would optimally support vertical &would optimally support vertical & horizontal stresses placed on it by denturehorizontal stresses placed on it by denture base.base. www.indiandentalacademy.comwww.indiandentalacademy.com
  93. 93. MASTICATORY LOADSMASTICATORY LOADS Natural teeth exert 44lb [20Natural teeth exert 44lb [20 kg].kg]. Complete dentures exert 13 – 16 lb [ 6 – 8 Kg ].Complete dentures exert 13 – 16 lb [ 6 – 8 Kg ]. Edentulous patients decrease the amount ofEdentulous patients decrease the amount of forces on the tissues by selecting softer foods.forces on the tissues by selecting softer foods. www.indiandentalacademy.comwww.indiandentalacademy.com
  94. 94. AREA OF SUPPORTAREA OF SUPPORT Watt in 1961 computed the mean dentureWatt in 1961 computed the mean denture bearing area to be;bearing area to be;  22.96 cm sq in edentulous maxilla.22.96 cm sq in edentulous maxilla. 12.25 cm sq in edentulous mandible.12.25 cm sq in edentulous mandible. 45 cm sq is the average periodontal45 cm sq is the average periodontal membrane area in each jaw with naturalmembrane area in each jaw with natural teeth.teeth. Further more the basal seat becomesFurther more the basal seat becomes progressively smaller as residual ridgesprogressively smaller as residual ridges resorb.resorb. www.indiandentalacademy.comwww.indiandentalacademy.com
  95. 95. Functional and parafunctionalFunctional and parafunctional considerationsconsiderations  Masticatory system seems to function bestMasticatory system seems to function best in an environment of continuing functionalin an environment of continuing functional equilibrium .[Moyer's 1969}.equilibrium .[Moyer's 1969}.  Primary components of human dentalPrimary components of human dental occlusion are;occlusion are;  1.The dentition.1.The dentition.  2.The neuromuscular system and2.The neuromuscular system and  3. Craniofacial structures.3. Craniofacial structures. www.indiandentalacademy.comwww.indiandentalacademy.com
  96. 96. The dentition develops in a milieu that isThe dentition develops in a milieu that is characterized by a period of dental alveolarcharacterized by a period of dental alveolar and craniofacial adaptability which is also aand craniofacial adaptability which is also a time when motor skills and neuromusculartime when motor skills and neuromuscular learning are developed.learning are developed. www.indiandentalacademy.comwww.indiandentalacademy.com
  97. 97. DentitionDentition www.indiandentalacademy.comwww.indiandentalacademy.com
  98. 98. Complete denture service is characterized byComplete denture service is characterized by an integration of biologic information withan integration of biologic information with instrumentation, techniques, and use ofinstrumentation, techniques, and use of materials.materials. Complete dentures are designed so that theirComplete dentures are designed so that their occlusal surfaces permit both functional andocclusal surfaces permit both functional and Para functional movements of the mandible.Para functional movements of the mandible. Orofacial and tongue muscles play anOrofacial and tongue muscles play an important role in retaining and stabilizingimportant role in retaining and stabilizing complete dentures.complete dentures. www.indiandentalacademy.comwww.indiandentalacademy.com
  99. 99. This is accomplished by arrangement of theThis is accomplished by arrangement of the artificial teeth to occupy a “neutral zone“ inartificial teeth to occupy a “neutral zone“ in the edentulous mouth so that the teeth willthe edentulous mouth so that the teeth will occupy a space determined by the functionaloccupy a space determined by the functional balance of the orofacial and tonguebalance of the orofacial and tongue musculature. Thus the teeth in the dental archmusculature. Thus the teeth in the dental arch need not necessarily be placed directly overneed not necessarily be placed directly over the residual ridges.the residual ridges. www.indiandentalacademy.comwww.indiandentalacademy.com
  100. 100. Neutral zoneNeutral zone www.indiandentalacademy.comwww.indiandentalacademy.com
  101. 101. FUNCTIONFUNCTION Mastication and swallowingMastication and swallowing During masticatory movements theDuring masticatory movements the tongue and cheek muscles play antongue and cheek muscles play an essential role in keeping the food bolusessential role in keeping the food bolus between the occlusal surface of thebetween the occlusal surface of the teeth.teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  102. 102. Deviation from the normal path ofDeviation from the normal path of mandibular movements can injure themandibular movements can injure the tongue, buccal mucosa and even the teethtongue, buccal mucosa and even the teeth and their supporting tissues . so the dentistand their supporting tissues . so the dentist must place teeth with in the confines ofmust place teeth with in the confines of functional balance of the musculaturefunctional balance of the musculature involved in controlling the food bolusinvolved in controlling the food bolus between the occlusal surface of the teeth.between the occlusal surface of the teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  103. 103. The maximal bite force in denture wearers isThe maximal bite force in denture wearers is five to six times less than in dentulousfive to six times less than in dentulous subjects.subjects. Edentulous patient are clearly handicapped inEdentulous patient are clearly handicapped in masticatory function and even clinicallymasticatory function and even clinically satisfactory complete dentures are poorsatisfactory complete dentures are poor substitutes for natural teeth.substitutes for natural teeth. www.indiandentalacademy.comwww.indiandentalacademy.com
  104. 104. Mandibular movementsMandibular movements The dentulous person usually demonstrateThe dentulous person usually demonstrate smooth jaw motion during mastication. It issmooth jaw motion during mastication. It is shaped some what like a tear drop, whenshaped some what like a tear drop, when viewed in the frontal plane. On the otherviewed in the frontal plane. On the other hand, the edentulous patient will often havehand, the edentulous patient will often have a distortion of this movement with thea distortion of this movement with the process becoming more random and inprocess becoming more random and in discriminate.discriminate. www.indiandentalacademy.comwww.indiandentalacademy.com
  105. 105. During the closing part of the cycle, theDuring the closing part of the cycle, the dentulous subjects, will decelerate, thedentulous subjects, will decelerate, the movement just before tooth contact tomovement just before tooth contact to dampen the effect of closure on thedampen the effect of closure on the dentition, but edentulous person will seemsdentition, but edentulous person will seems to elevate the jaw at a constant velocity withto elevate the jaw at a constant velocity with no deceleration near the end of the closure.no deceleration near the end of the closure. www.indiandentalacademy.comwww.indiandentalacademy.com
  106. 106. The edentulous patient will not develop theThe edentulous patient will not develop the same isometric tension on artificial denturesame isometric tension on artificial denture that is attained by people closing withthat is attained by people closing with natural teeth.natural teeth. Recent evidences indicates that jawRecent evidences indicates that jaw movement is controlled and coordinated bymovement is controlled and coordinated by central pattern generator or “ chewingcentral pattern generator or “ chewing center”.center”. www.indiandentalacademy.comwww.indiandentalacademy.com
  107. 107. Which is activated by impulse from cerebralWhich is activated by impulse from cerebral cortex or from peripheral sensory receptors.cortex or from peripheral sensory receptors. At one time , it was believed that masticationAt one time , it was believed that mastication was the result of the alteration of the simplewas the result of the alteration of the simple brain stem reflexes.brain stem reflexes. This concept has been replaced by the ideaThis concept has been replaced by the idea that central pattern generator , once initiated,that central pattern generator , once initiated, that produce rhythmic alternation of openingthat produce rhythmic alternation of opening and closing movements that constituteand closing movements that constitute mastication.mastication. www.indiandentalacademy.comwww.indiandentalacademy.com
  108. 108. This rhythmic act, how ever can be modifiedThis rhythmic act, how ever can be modified by the shape, size and consistency of theby the shape, size and consistency of the bolus as well as by other variables.bolus as well as by other variables. Since neurosensory input, such as fromSince neurosensory input, such as from periodontal and other receptors can influenceperiodontal and other receptors can influence the central pattern generator and the chewingthe central pattern generator and the chewing cycle, it is reasonable to consider that a statecycle, it is reasonable to consider that a state of edentulism will provide some what differentof edentulism will provide some what different neurosensory information to the neurologicalneurosensory information to the neurological control mechanism.control mechanism. www.indiandentalacademy.comwww.indiandentalacademy.com
  109. 109. For example.For example. Anesthesia experiment have demonstratedAnesthesia experiment have demonstrated that coordinated chewing can occur afterthat coordinated chewing can occur after sensory deprivation , how ever absence ofsensory deprivation , how ever absence of sensory information appears to affect thesensory information appears to affect the preciseness of occlusal contacts during jawpreciseness of occlusal contacts during jaw function.function. www.indiandentalacademy.comwww.indiandentalacademy.com
  110. 110.  The use of centric relation has its physiologicThe use of centric relation has its physiologic justification.justification.  In vast majority unconscious swallowing is carriedIn vast majority unconscious swallowing is carried out with mandible or at near centric relation. Thisout with mandible or at near centric relation. This unconscious reflex swallow is important inunconscious reflex swallow is important in developing dentition, as it influences thedeveloping dentition, as it influences the movement of teeth within the muscle matrix andmovement of teeth within the muscle matrix and this movement determines tooth position andthis movement determines tooth position and occlusal relations.occlusal relations. www.indiandentalacademy.comwww.indiandentalacademy.com
  111. 111.  The occlusion of complete denture is designed toThe occlusion of complete denture is designed to harmonize with this primitive reflex of patientsharmonize with this primitive reflex of patients unconscious swallow.unconscious swallow.  Tooth contacts and mandibular bracing againstTooth contacts and mandibular bracing against maxilla occurred during swallowing by C.Dmaxilla occurred during swallowing by C.D patients. This suggest that C.D occlusion must bepatients. This suggest that C.D occlusion must be compatible with forces developed duringcompatible with forces developed during deglutition to prevent disharmonious occlusaldeglutition to prevent disharmonious occlusal contact that can be caused to the basal seat .contact that can be caused to the basal seat . www.indiandentalacademy.comwww.indiandentalacademy.com
  112. 112. This factor is an important consideration inThis factor is an important consideration in treating edentulous patient, since thetreating edentulous patient, since the occlusal scheme to develop on completeocclusal scheme to develop on complete dentures should attempt to account for anydentures should attempt to account for any loss of ability to close to precise position.loss of ability to close to precise position. www.indiandentalacademy.comwww.indiandentalacademy.com
  113. 113. Temporomandibular jointsTemporomandibular joints changeschanges www.indiandentalacademy.comwww.indiandentalacademy.com
  114. 114. Although the relationship between occlusionAlthough the relationship between occlusion and degenerative joint disease is notand degenerative joint disease is not completely clear, the dentist is tempted tocompletely clear, the dentist is tempted to believe that a depleted or in adequately caredbelieve that a depleted or in adequately cared for dentition , obviously loads the TMJ .for dentition , obviously loads the TMJ . Denture wearers have been shown to sufferDenture wearers have been shown to suffer from degenerative changes of joints morefrom degenerative changes of joints more frequently than person with a complete naturalfrequently than person with a complete natural dentition , but this may be age related ratherdentition , but this may be age related rather than due to state of dentition.than due to state of dentition. www.indiandentalacademy.comwww.indiandentalacademy.com
  115. 115. Research strongly suggest that purely dentalResearch strongly suggest that purely dental factors may be important in etiology offactors may be important in etiology of degenerative joint disease of mandibulardegenerative joint disease of mandibular condyles.condyles. Clinical experience indicates that theClinical experience indicates that the application of sound prosthodontic principles,application of sound prosthodontic principles, accompanied by appropriate systemic careaccompanied by appropriate systemic care by a physician ,is usually adequate toby a physician ,is usually adequate to provide the patient with comfort.provide the patient with comfort. www.indiandentalacademy.comwww.indiandentalacademy.com
  116. 116. Tongue changesTongue changes The tongue is a highly mobile muscularThe tongue is a highly mobile muscular organ that merits careful attention during theorgan that merits careful attention during the construction of complete dentures. Inconstruction of complete dentures. In coordination with lips , cheek , palate , andcoordination with lips , cheek , palate , and pharynx, the tongue functions in speech,pharynx, the tongue functions in speech, mastication, and swallowing.mastication, and swallowing. www.indiandentalacademy.comwww.indiandentalacademy.com
  117. 117. The tongue is in intimate contact with aThe tongue is in intimate contact with a complete lower denture and its position incomplete lower denture and its position in relationship must be considered veryrelationship must be considered very carefully in each particular patient.carefully in each particular patient. In those patients in whom the genial tubercleIn those patients in whom the genial tubercle become extremely prominent due tobecome extremely prominent due to excessive resorption of the alveolar process,excessive resorption of the alveolar process, special attention must be paid in contouringspecial attention must be paid in contouring the lingual flange of a lower denture in orderthe lingual flange of a lower denture in order that the denture is not displaced every timethat the denture is not displaced every time the genioglossus muscle contracts.the genioglossus muscle contracts. www.indiandentalacademy.comwww.indiandentalacademy.com
  118. 118. The size of the tongue does not vary withThe size of the tongue does not vary with age. how ever, tooth loss can lead to widerage. how ever, tooth loss can lead to wider tongue morphology by virtue of antongue morphology by virtue of an overdevelopment of some parts of tongue’soverdevelopment of some parts of tongue’s intrinsic musculature.intrinsic musculature. Constant and habitual attempts to keep aConstant and habitual attempts to keep a loose maxillary denture in place can causeloose maxillary denture in place can cause these changes. The effect of this onthese changes. The effect of this on subsequent wearing must not be over looked.subsequent wearing must not be over looked. www.indiandentalacademy.comwww.indiandentalacademy.com
  119. 119. STRESS DISTRIBUTION TOSTRESS DISTRIBUTION TO DENTURE SUPPORTING TISSUESDENTURE SUPPORTING TISSUES The need to full filling fundamental objectiveThe need to full filling fundamental objective of good prosthodontic treatment is underof good prosthodontic treatment is under scored by the preceding information.scored by the preceding information. All possible methods to ensure continueAll possible methods to ensure continue tissue health by minimizing potentialtissue health by minimizing potential traumatic effect by complete denture weartraumatic effect by complete denture wear should be undertaken.should be undertaken. www.indiandentalacademy.comwww.indiandentalacademy.com
  120. 120. The capability of supporting tissues shouldThe capability of supporting tissues should be improved when ever possible bybe improved when ever possible by adequate preparation of both hard and softadequate preparation of both hard and soft tissues.tissues. www.indiandentalacademy.comwww.indiandentalacademy.com
  121. 121. Mucosal health may be promoted byMucosal health may be promoted by hygienic and therapeutic measures, andhygienic and therapeutic measures, and tissue conditioning techniques may betissue conditioning techniques may be applied when appropriate.applied when appropriate.  Complete denture base extension withinComplete denture base extension within morphologic and functional limits canmorphologic and functional limits can reduce considerably the occlusal load onreduce considerably the occlusal load on the unit area of mucosa.the unit area of mucosa. Resilient denture base lining materials mayResilient denture base lining materials may be used.be used. The masticatory loading may be decreasedThe masticatory loading may be decreased by reduction of the area of the occlusalby reduction of the area of the occlusal table.table. www.indiandentalacademy.comwww.indiandentalacademy.com
  122. 122. Currently, for practical purposes, denture basesCurrently, for practical purposes, denture bases are made of rigid materials. These may be oneare made of rigid materials. These may be one of various types of resins, metals, orof various types of resins, metals, or combinations of them the dentist mustcombinations of them the dentist must recognize that the prolonged contact of theserecognize that the prolonged contact of these vases with their underlying tissues.vases with their underlying tissues.  Furthermore, the tissues are susceptible toFurthermore, the tissues are susceptible to changes caused by the increased longevity ofchanges caused by the increased longevity of patients with the effects of aging on tissues , aspatients with the effects of aging on tissues , as well as the functional and para functionalwell as the functional and para functional demands that patients make on their denturedemands that patients make on their denture supporting tissues .supporting tissues . www.indiandentalacademy.comwww.indiandentalacademy.com
  123. 123. Many dentists have been tempted to equateMany dentists have been tempted to equate the prevalent residual ridge reduction in thethe prevalent residual ridge reduction in the edentulous population with excessiveedentulous population with excessive stresses that are imposed on these ridges.stresses that are imposed on these ridges. Up to now there is no specific evidence toUp to now there is no specific evidence to indicate any one factor as causing advancedindicate any one factor as causing advanced ridge reduction.ridge reduction. However, strong theoretical evidence exists toHowever, strong theoretical evidence exists to justify the development of permanentlyjustify the development of permanently resilient lining materials in complete dentures.resilient lining materials in complete dentures. www.indiandentalacademy.comwww.indiandentalacademy.com
  124. 124. These materials could permit a widerThese materials could permit a wider dispersion of forces and result in a lowerdispersion of forces and result in a lower force per unit area being transmitted toforce per unit area being transmitted to supporting tissues.supporting tissues. Such a soft denture lining material couldSuch a soft denture lining material could effectively increase the thickness of the oraleffectively increase the thickness of the oral tissue by serving as a analog of thetissue by serving as a analog of the mucoperiostium with its relatively low elasticmucoperiostium with its relatively low elastic modulus [kydd and mandley, 1967]modulus [kydd and mandley, 1967] www.indiandentalacademy.comwww.indiandentalacademy.com
  125. 125. The distance increment between the hardThe distance increment between the hard denture base and the non-resilient bonydenture base and the non-resilient bony support would be increased withsupport would be increased with hypothetical salutary long tern results. Thehypothetical salutary long tern results. The academy of denture prosthetics listed ideasacademy of denture prosthetics listed ideas for the improvement of denture basefor the improvement of denture base materials and cites the following desirablematerials and cites the following desirable properties;properties; 1. Possessing variable consistency under1. Possessing variable consistency under varying mouth conditions.varying mouth conditions. 2. Selectively resilient, compatible with2. Selectively resilient, compatible with resiliency of the tissues.resiliency of the tissues. 3. Resilient with quick recovery able to3. Resilient with quick recovery able to recover shape quickly after deformingrecover shape quickly after deforming forces are removed.forces are removed.www.indiandentalacademy.comwww.indiandentalacademy.com
  126. 126. 4. Compressible on tissue side but rigid on4. Compressible on tissue side but rigid on occlusal side.occlusal side. 5. Shock absorbing.5. Shock absorbing. 6. Controlling or reducing forces transmitted6. Controlling or reducing forces transmitted through the base to the underlying tissue.through the base to the underlying tissue. 7. Possessing flexibility that can be controlled7. Possessing flexibility that can be controlled and varied in processing as desired.and varied in processing as desired. www.indiandentalacademy.comwww.indiandentalacademy.com
  127. 127. The work of kydd and associates [1971] onThe work of kydd and associates [1971] on pressures in the oral cavity has posed anpressures in the oral cavity has posed an excellent argument favoring the employmentexcellent argument favoring the employment of soft lining materials.of soft lining materials. They argue that during function andThey argue that during function and parafunction, pressures are applied by theparafunction, pressures are applied by the dentures, which will displace the soft tissues.dentures, which will displace the soft tissues. These pressures deform the mucoperiostiumThese pressures deform the mucoperiostium and interfere with circulation of blood,and interfere with circulation of blood, nutrients, and metabolites.nutrients, and metabolites. Several studies have demonstrated changesSeveral studies have demonstrated changes in soft-tissue contour as a result of mechanicalin soft-tissue contour as a result of mechanical stress.stress. www.indiandentalacademy.comwww.indiandentalacademy.com
  128. 128. Kydd and associates describes theKydd and associates describes the viscoelastic character of denture supportingviscoelastic character of denture supporting tissue.tissue. There is an initial elastic compression of softThere is an initial elastic compression of soft tissues that takes place instantly ontissues that takes place instantly on application of load.application of load. After the elastic phase there is delayed elasticAfter the elastic phase there is delayed elastic deformation of the tissue that takes placedeformation of the tissue that takes place slowly and continues to diminish in rate ofslowly and continues to diminish in rate of changes as duration of load is extended .changes as duration of load is extended . An instantaneous elastic decompressionAn instantaneous elastic decompression occurs when the pressure is removed. Thisoccurs when the pressure is removed. This is followed by a continuing delayed elasticis followed by a continuing delayed elastic recovery.recovery. www.indiandentalacademy.comwww.indiandentalacademy.com
  129. 129. www.indiandentalacademy.comwww.indiandentalacademy.com
  130. 130. www.indiandentalacademy.comwww.indiandentalacademy.com
  131. 131. Histological, the stressed oral mucosa hasHistological, the stressed oral mucosa has an altered morphologic pattern. The loadedan altered morphologic pattern. The loaded epithelium demonstrates a decease in theepithelium demonstrates a decease in the depth of the epithelial ridges, and thedepth of the epithelial ridges, and the connective tissues papillae are obliteratedconnective tissues papillae are obliterated the extent of these alterations varies withthe extent of these alterations varies with the force and duration of the applied force.the force and duration of the applied force. Human soft tissues take as long as 4 hoursHuman soft tissues take as long as 4 hours to recover after moderate loading for 10to recover after moderate loading for 10 minutes.minutes. www.indiandentalacademy.comwww.indiandentalacademy.com
  132. 132.  A Change in tissue displaceability can alsoA Change in tissue displaceability can also be demonstrated as being a function of age.be demonstrated as being a function of age. A longer period of time is needed for theA longer period of time is needed for the recovery of displaced mucosa in elderlyrecovery of displaced mucosa in elderly people (68 to 70 years) when compared withpeople (68 to 70 years) when compared with young adults (21 to 27 years).young adults (21 to 27 years). It appears that any Intraoral prosthesis canIt appears that any Intraoral prosthesis can be intruded into the denture-supporting oralbe intruded into the denture-supporting oral mucosa by up to 20% of its resting thicknessmucosa by up to 20% of its resting thickness with relatively small occluding forces (0.2with relatively small occluding forces (0.2 gmmsq) .gmmsq) . Lindan (1961) has shown that pressures asLindan (1961) has shown that pressures as small as 0.13 gmmsq will displace humansmall as 0.13 gmmsq will displace human soft tissues to 95% of their resting thickness.soft tissues to 95% of their resting thickness.www.indiandentalacademy.comwww.indiandentalacademy.com
  133. 133. This indicates that impression materials, forThis indicates that impression materials, for example, must flow readily and with minimalexample, must flow readily and with minimal pressure when an impression is made.pressure when an impression is made. www.indiandentalacademy.comwww.indiandentalacademy.com
  134. 134. Cutright and associates( 1976) recordedCutright and associates( 1976) recorded pressures under complete maxillary dentures.pressures under complete maxillary dentures. They used a closed fluid system connected toThey used a closed fluid system connected to a pressure transducer and recorder to registera pressure transducer and recorder to register positive and negative pressures in fourpositive and negative pressures in four subjects at four locations. Each subjectsubjects at four locations. Each subject performed a number of controlled masticatoryperformed a number of controlled masticatory and non-masticatory activities.and non-masticatory activities. Their findings indicate that a number of non-Their findings indicate that a number of non- masticatory activities (smoking, swallowing,masticatory activities (smoking, swallowing, speaking) created as much, or more, positivespeaking) created as much, or more, positive and negative pressures on the supportingand negative pressures on the supporting tissues as the masticatory activities.tissues as the masticatory activities. www.indiandentalacademy.comwww.indiandentalacademy.com
  135. 135. IT is tempting to suggest that theseIT is tempting to suggest that these pressures could affect the soft tissue andpressures could affect the soft tissue and the blood and lymph vessels, perhapsthe blood and lymph vessels, perhaps causing sclerosis, diminished blood supply,causing sclerosis, diminished blood supply, and the many morphologic variants weand the many morphologic variants we encounter in our edentulous patients.encounter in our edentulous patients.  Cutright and associates concluded that theCutright and associates concluded that the effect of these continually occurring, non –effect of these continually occurring, non – masticatory induced pressure changes andmasticatory induced pressure changes and waves may well be of greater significancewaves may well be of greater significance than that of mastication.than that of mastication. www.indiandentalacademy.comwww.indiandentalacademy.com
  136. 136. The amount of force generated by a patientsThe amount of force generated by a patients masticatory system is not controlled by themasticatory system is not controlled by the dentist.dentist. The dentist can seek to minimize forceThe dentist can seek to minimize force distribution by maximizing denture basedistribution by maximizing denture base coverage and developing an optimal denturecoverage and developing an optimal denture occlusion.occlusion. Occlusal surfaces of the artificial teeth canOcclusal surfaces of the artificial teeth can be smaller, and the patient can be instructedbe smaller, and the patient can be instructed to handle parafunctional habits throughto handle parafunctional habits through education and understanding.education and understanding. www.indiandentalacademy.comwww.indiandentalacademy.com
  137. 137. Forces can also be reduced or diluted by useForces can also be reduced or diluted by use of a permanently resilient liner if suchof a permanently resilient liner if such materials are readily available.materials are readily available. The time factor can be controlled to a largeThe time factor can be controlled to a large extent by frequent rest periods for the denture-extent by frequent rest periods for the denture- supporting tissues, Leaving the dentures out ofsupporting tissues, Leaving the dentures out of the mouth during sleeping hours isthe mouth during sleeping hours is recommended.recommended. Oral tissues were designed to be exposed toOral tissues were designed to be exposed to oral fluids and to be stimulated by the action oforal fluids and to be stimulated by the action of tongue, lips, and cheeks. Nocturnal rest cantongue, lips, and cheeks. Nocturnal rest can achieve this objective, along with a quantitativeachieve this objective, along with a quantitative diminution in the duration of exposure of thesediminution in the duration of exposure of these tissues to stress.tissues to stress. www.indiandentalacademy.comwww.indiandentalacademy.com
  138. 138. The efficiency of temporary soft or treatmentThe efficiency of temporary soft or treatment liners in routine prosthodontic practice hasliners in routine prosthodontic practice has proved the value of such an approach inproved the value of such an approach in treating soft-tissue problems.treating soft-tissue problems. The contribution of permanent liners towardThe contribution of permanent liners toward the maintenance of supporting tissuethe maintenance of supporting tissue integrity and morphology is still hypothetical.integrity and morphology is still hypothetical. www.indiandentalacademy.comwww.indiandentalacademy.com
  139. 139. The most frequently used liners are usuallyThe most frequently used liners are usually produced from silicone rubbers or acrylicproduced from silicone rubbers or acrylic resins. Recent reports also suggests theresins. Recent reports also suggests the possible employment of hydrophilic polymerspossible employment of hydrophilic polymers and fluoropolymers .and fluoropolymers . The silicone rubber resilient liners, whenThe silicone rubber resilient liners, when properly used, are the most appropriate ofproperly used, are the most appropriate of the various types available, but they too arethe various types available, but they too are only temporary expedients. These materialsonly temporary expedients. These materials may support yeast growth( e.g., Candidamay support yeast growth( e.g., Candida Albicans).Albicans). www.indiandentalacademy.comwww.indiandentalacademy.com
  140. 140. They must be observed regularly by theThey must be observed regularly by the dentist and replaced when unsatisfactory.dentist and replaced when unsatisfactory.  The use of proper cleansers and homeThe use of proper cleansers and home care habits have contributed to thecare habits have contributed to the employment of these materials withemployment of these materials with significantly beneficial results.significantly beneficial results. It must be emphasized that the use of theseIt must be emphasized that the use of these materials does not preclude adherence tomaterials does not preclude adherence to the fundamental principles of completethe fundamental principles of complete denture construction. When useddenture construction. When used intelligently, resilient liners can be anintelligently, resilient liners can be an excellent adjunct in prosthodontics.excellent adjunct in prosthodontics. www.indiandentalacademy.comwww.indiandentalacademy.com
  141. 141. Posselt (1952) showed that the borderPosselt (1952) showed that the border movements of the mandible weremovements of the mandible were reproducible and that all other movementsreproducible and that all other movements took place within the confines of his classictook place within the confines of his classic “envelopes of motion.”“envelopes of motion.” These researchers concluded that theThese researchers concluded that the passive hinge movement has a constantpassive hinge movement has a constant and definite rotational and posterior borderand definite rotational and posterior border path is of tremendous practical significancepath is of tremendous practical significance in the treatment ofin the treatment of Prosthodontic patients.Prosthodontic patients. www.indiandentalacademy.comwww.indiandentalacademy.com
  142. 142. However, this reproducibility has beenHowever, this reproducibility has been established in healthy young persons only.established in healthy young persons only. Tallgren (1957) has shown that morphologicTallgren (1957) has shown that morphologic face height increased with age in personsface height increased with age in persons possessing an intact or relatively definition.possessing an intact or relatively definition.  However, a premature reduction inHowever, a premature reduction in morphologic face height occurs with attritionmorphologic face height occurs with attrition or abrasion of teeth. This reduction is evenor abrasion of teeth. This reduction is even more conspicuous in edentulous Andmore conspicuous in edentulous And complete denture-wearing patients.complete denture-wearing patients. www.indiandentalacademy.comwww.indiandentalacademy.com
  143. 143. Maxillomandibular morphologic changesMaxillomandibular morphologic changes take place slowly over a period of years andtake place slowly over a period of years and depend on the balance of osteoblastic anddepend on the balance of osteoblastic and osteoblastic activity.osteoblastic activity. The articular surfaces of theThe articular surfaces of the temperomandibular joints are also involved,temperomandibular joints are also involved, and at these sites growth and remodelingand at these sites growth and remodeling are mediated through the proliferativeare mediated through the proliferative activity of the articular cartilages.activity of the articular cartilages. www.indiandentalacademy.comwww.indiandentalacademy.com
  144. 144. Tallgren(1972) has shown that in completeTallgren(1972) has shown that in complete denture wearers the mean reduction isdenture wearers the mean reduction is height of the mandibular process, asheight of the mandibular process, as measured in the anterior region was 6.6measured in the anterior region was 6.6 mm, approximately four times greater thanmm, approximately four times greater than the mean reduction occurring in thethe mean reduction occurring in the maxillary process.maxillary process. www.indiandentalacademy.comwww.indiandentalacademy.com
  145. 145. The unconscious or reflex swallow isThe unconscious or reflex swallow is important in the developing dentition. Theimportant in the developing dentition. The act and frequency of swallowing areact and frequency of swallowing are important influences in the movement ofimportant influences in the movement of teeth within the muscle matrix, and thisteeth within the muscle matrix, and this movement determines the tooth positionmovement determines the tooth position and occlusal relations (Moyers).and occlusal relations (Moyers). www.indiandentalacademy.comwww.indiandentalacademy.com
  146. 146. Temporomandibular joints changesTemporomandibular joints changes Several authors claim that impaired dentalSeveral authors claim that impaired dental efficiency resulting from partial tooth loss andefficiency resulting from partial tooth loss and absence of, or incorrect, prosthodonticabsence of, or incorrect, prosthodontic treatment can bring about TMJ pain andtreatment can bring about TMJ pain and dysfunction or even degenerative changes indysfunction or even degenerative changes in the joint.the joint. www.indiandentalacademy.comwww.indiandentalacademy.com
  147. 147. COSMETIC CHANGES ANDCOSMETIC CHANGES AND INDIVIDUAL ADAPTIVEINDIVIDUAL ADAPTIVE RESPONSESRESPONSES Morphological changes associated with theMorphological changes associated with the edentulous state.edentulous state. 1. Deepening of the nasolabial groove.1. Deepening of the nasolabial groove. 2. Loss of labio dental angle.2. Loss of labio dental angle. 3. Decrease in horizontal labial angle.3. Decrease in horizontal labial angle. 4. Narrowing of lips.4. Narrowing of lips. 5. Increase in columella philtral angle.5. Increase in columella philtral angle. 6. Prognathic appearance.6. Prognathic appearance. www.indiandentalacademy.comwww.indiandentalacademy.com
  148. 148. www.indiandentalacademy.comwww.indiandentalacademy.com
  149. 149. www.indiandentalacademy.comwww.indiandentalacademy.com
  150. 150. www.indiandentalacademy.comwww.indiandentalacademy.com
  151. 151. ADAPTIVE RESPONSE TOADAPTIVE RESPONSE TO COMPLETE DENTURESCOMPLETE DENTURES It requires adaptation related to learning,It requires adaptation related to learning, muscular skill and motivation.muscular skill and motivation. Helping a patient adapt to completeHelping a patient adapt to complete dentures can be one of the most difficult butdentures can be one of the most difficult but one of the most rewarding aspect of clinicalone of the most rewarding aspect of clinical dentistry.dentistry. The patient who has worn a complete upperThe patient who has worn a complete upper denture opposing a few natural anteriordenture opposing a few natural anterior mandibular teeth will usually find a completemandibular teeth will usually find a complete lower denture difficult to adapt to.lower denture difficult to adapt to. www.indiandentalacademy.comwww.indiandentalacademy.com
  152. 152. Such a patient has to contend with anSuch a patient has to contend with an alteration in size and orientation of thealteration in size and orientation of the tongue.tongue. It must be realized that edentulous patientsIt must be realized that edentulous patients expect and are expected to adapt to theexpect and are expected to adapt to the dentures more or less instantaneously anddentures more or less instantaneously and that the adaptation must take place in thethat the adaptation must take place in the context of the patients oral , systemic ,context of the patients oral , systemic , emotional and psychologic states .emotional and psychologic states . www.indiandentalacademy.comwww.indiandentalacademy.com
  153. 153. Facility for learning and co-ordinationFacility for learning and co-ordination appears to diminish with age. Advancingappears to diminish with age. Advancing age tends to be accompanied byage tends to be accompanied by progressive atrophy of elements of cerebralprogressive atrophy of elements of cerebral cortex and a consequent loss in the facilitycortex and a consequent loss in the facility of co-ordination occurs.of co-ordination occurs. www.indiandentalacademy.comwww.indiandentalacademy.com
  154. 154. CONCLUSIONCONCLUSION The success of prosthetic treatment isThe success of prosthetic treatment is predicated not only on manual dexterity ,predicated not only on manual dexterity , but also on the ability of the dentist to relatebut also on the ability of the dentist to relate to patients and to understand their needs.to patients and to understand their needs. The ability to understand and recognize theThe ability to understand and recognize the problems of edentulous patients and toproblems of edentulous patients and to reassure them has proved to be of greatreassure them has proved to be of great clinical value.clinical value. www.indiandentalacademy.comwww.indiandentalacademy.com
  155. 155. BibliographyBibliography  Essentials of complete denture-WinklerEssentials of complete denture-Winkler  Syllabus of Complete Denture-HeartwellSyllabus of Complete Denture-Heartwell  Prosthodontic treatment for edentulousProsthodontic treatment for edentulous patient-Boucherpatient-Boucher  Clinical Dental Prosthetics-FennClinical Dental Prosthetics-Fenn  Removable Partial Prsothodontics-Removable Partial Prsothodontics- McCrackenMcCracken www.indiandentalacademy.comwww.indiandentalacademy.com
  156. 156. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com

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