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Support/ dentistry dental implants

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Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.

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  • 1. 11 Good MorningGood Morning www.indiandentalacademy.comwww.indiandentalacademy.com
  • 2. 22 SUPPORT IN COMPLETE DENTURE INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com
  • 3. 33 CONTENTS: INTRODUCTIONINTRODUCTION DEFINITIONSDEFINITIONS COMPARISION OF SUPPORT IN DENTULOUS ANDCOMPARISION OF SUPPORT IN DENTULOUS AND EDENTULOUSEDENTULOUS ANATOMY OF SUPPORTING STRUCTURESANATOMY OF SUPPORTING STRUCTURES TYPES OF SUPPORTTYPES OF SUPPORT NATURE OF SUPPORTING TISSUESNATURE OF SUPPORTING TISSUESwww.indiandentalacademy.comwww.indiandentalacademy.com
  • 4. 44 DENTURE BEARING AREAS METHODS TO IMPROVE SUPPORT AGE CHANGES IN SUPPORTING TISSUES CONCLUSION www.indiandentalacademy.comwww.indiandentalacademy.com
  • 5. 55www.indiandentalacademy.comwww.indiandentalacademy.com
  • 6. 66 DEFINITION: 1. Support : The foundation area on which a dental prosthesis rests, 2. Supporting Area : The surface of the mouth available for support of a denture. 3. Supporting Area : Those areas of the maxillary and mandibular edentulous ridges that are considered best suited to carry the forces of mastication when the dentures are in function. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 7. 77 According to Jacobson and KroI, complete denture support is the resistance to vertical movement of the denture base towards the ridge •According to Boucher, Support is the resistance of a denture to the vertical components of mastication and to occlusal or other forces applied in a direction towards the basal seat www.indiandentalacademy.comwww.indiandentalacademy.com
  • 8. 88 COMPARISON OF SUPPORT IN DENTULOUS AND EDENTULOUS: The masticatory system is made up of morphological, functional and behavioral components. The interactions of these closely related components are affected by changes in the mechanism of support for a dentition when natural teeth are replaced by artificial ones. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 9. 99www.indiandentalacademy.comwww.indiandentalacademy.com
  • 10. 1010 Mechanisms of Tooth Support: •The masticatory apparatus is involved in the process of trituration of food. Direct responsibility for this task falls on the teeth and their supporting tissues. •Teeth function properly only if adequately supported. This support is provided by an organ composed of soft and hard connective tissues, the periodontium www.indiandentalacademy.comwww.indiandentalacademy.com
  • 11. 1111 The periodontium attaches the teeth to the bone of the jaws, providing a resilient suspensory apparatus resistant to functional forces. It allows the teeth to adjust their position when under stress. The periodontal ligament provides the means by which force exerted on the tooth is transmitted to the bone that supports it. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 12. 1212 The two principal functions of the periodontium are, – support and positional adjustment of the teeth – secondary and dependent function of sensory perception. – The patient needing complete denture therapy is deprived of periodontal support, and the entire mechanism of functional load transmission to the supporting tissues is altered. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 13. 1313 The occlusal forces exerted on the teeth are controlled by the neuromuscular mechanisms of the masticatory system. Reflex mechanisms with receptors in the muscles, tendons, joint and periodontal structures regulate mandibular movements. Through normal function the periodontal structures in a healthy dentition undergo characteristic mechanical stress. The most prominent feature of physiological occlusal force is their intermittent, rhythmic and dynamic nature. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 14. 1414 The greatest forces acting on the teeth are normally produced during mastication and deglutition, and they are essentially vertical in direction. Each thrust is of short duration, and for most people, at least, chewing is restricted to short periods during the day. Deglutition on the other hand, occurs about 500 times a day and tooth contacts during swallowing are usually of longer duration than those occurring during chewing.. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 15. 1515 During mastication, biting forces are transmitted through the bolus to the opposing teeth whether the teeth make contact or not. These forces increase steadily depending on the nature of the food fragment), reach a peak and abruptly return to zero. The magnitude, rise time and interval between thrusts differ among persons and depend on the consistency of the food, the point in the chewing sequence and the dental status. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 16. 1616 The direction of forces is principally perpendicular to the occlusal plane in normal function, but the forward angulations of most natural teeth leads to the introduction of a horizontal component that tends to tilt the teeth mesially as well as buccally or lingually. It has been calculated that the total time during which the teeth are subjected to functional forces of mastication and deglutition during an entire day amounts to approximately 17.517.5 minutesminutes More than half of this time is attributable to jaw-closing forces applied during deglutition. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 17. 1717 Mechanisms of Complete Denture Support: •The basic problem in the treatment of edentulous patients lies in the nature of the difference between the ways in which natural teeth and their artificial replacements are attached to the supporting bone •The approximate area of 45 cm in each circle combines with viscoelasticity sophisticated sensory mechanism and osteogenesis regulation potential to cope with the directions, magnitudes and frequencies of occlusal loading. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 18. 1818 Masticatory loads: natural teeth : 44 lb (20 kg) complete dentures : 13-16 lb (6-8 kg) Mucosa Support : Mean Denture Bearing Area Maxilla: 22.96 cm2 Mandible : 12.15 cm Periodontal Ligament Area: 45 cm2 www.indiandentalacademy.comwww.indiandentalacademy.com
  • 19. 1919 Residual Ridge : •Consists of denture bearing mucosa the submucosa and periosteum and the underlying residual alveolar bone. •Residual bone is that bone of the alveolar process that remains after teeth are lost. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 20. 2020 • A variety of changes occur in the residual bone after tooth extraction and wearing of complete dentures. • While alveolar bone supporting natural teeth receives tensile loads through a large area of periodontal ligament, the edentulous residual ridge receives vertical, diagonal and horizontal loads applied by a denture with a surface area much smaller than the total area of the periodontal ligament of the natural teeth that had been present. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 21. 2121 •One of the few firm facts relating to edentulous patients is that the wearing of dentures is almost invariably accompanied by an undesirable bone loss. •Two concepts have been advanced concerning the inevitable loss of residual bone, > One contends that as a consequence of loss of the palatal structures, variable progressive bone reduction occurs. > Other maintains that residual bone loss is not a necessary consequence of tooth removal but is dependent on a series of poorly understood factors. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 22. 2222 •mechanism of support is further complicated by the fact that complete dentures move in relation to the underlying bone during function •The movement is related to the resiliency of the supporting mucosa and the inherent instability of the dentures during function. •Movement of denture bases in any direction on their basal seats can cause tissue damage www.indiandentalacademy.comwww.indiandentalacademy.com
  • 23. 2323 •The denture base must extend as far as possible without interfering in the health or function of the tissues •It is convenient to regard the impression surface of a denture as comprising two areas, > stress bearing or supporting area. > peripheral or limiting area. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 24. 2424 ANATOMY OF SUPPORTING STRUCTURES : •The foundation for dentures is made up of bone of the hard palate and residual ridge, covered by mucous membrane. •The denture base rests on the mucous membrane, which serves as a cushion between the base and the supporting bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 25. 2525 Mucous Membrane: The mucous membrane is composed of mucosa and submucosa The submucosa is formed by connective tissue that varies in character from dense to loose areolar tissue and also varies considerably in thickness. The submucosa may contain glandular, fat or muscle cells and transmits the blood and nerve supply to the mucosa. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 26. 2626 •Where the mucous membrane is attached to bone, the attachment occurs between the submucosa and the periosteal covering of the bone •The mucosa is formed by stratified squamous epithelium which often is keratinised, and a subjacent narrow layer of connective tissue known as the lamina propria. •in the edentulous person, the mucosa covering the hard palate and the crest of the residual ridge, including the residual attached gingiva is classified as masticatorymasticatory mucosamucosa www.indiandentalacademy.comwww.indiandentalacademy.com
  • 27. 2727www.indiandentalacademy.comwww.indiandentalacademy.com
  • 28. 2828 • The thickness and consistency of the submucosa are largely responsible for the support that the mucous membrane affords a denture, because in most instances, the submucosa makes up the bulk of the mucous membrane. •In a healthy mouth, the submucosa is firmly attached to the periosteum of the underlying supporting bone and will usually withstand successfully the pressures of the dentures. •When the submucosal layer is thin, the soft tissues will be non-resilient, and the mucous membrane will be easily traumatized. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 29. 2929 Hard Palate :Hard Palate : •The palatine processes of the maxilla and the palatine bone form the foundation for the hard palate and provide considerable support for the denture. •A cross section of the hard palate shows that the palate is covered by soft tissue of varying thickness, even though the epithelium is keratinized throughout. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 30. 3030www.indiandentalacademy.comwww.indiandentalacademy.com
  • 31. 3131 • Anterolaterally, the submucosa contains adipose tissue, and posterotaterally it contains glandular tissue •This tissue is displaceable, and although it contributes to the support of the denture, the horizontal portion of the hard palate lateral to the midline provides the primary support area for the denture. •In the area of the rugae, the palate is set at an angle to the residual ridge and is rather thinly covered by soft tissue. This area contributes to the stress bearing role, though in a secondary capacity. •The submucosa covering the incisive papilla and the nasopalatine canal contains the nasopalatine vessels and nerves. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 32. 3232www.indiandentalacademy.comwww.indiandentalacademy.com
  • 33. 3333 Support may be considered from two points of view, •First, the maxillary and mandibular denture should conform to the underlying tissues so that the occlusal surfaces can correctly oppose one another at the time of insertion. •Bilateral simultaneous contact should exist both at initial closure and under functional loading. •Second, the denture base should maintain this relationship for a period of time. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 34. 3434 • Initial denture support is achieved by using impression procedures that provide optimal extension and functional loading of the supporting tissues which vary in their resiliency. • Long term support is obtained by directing the forces of occlusal loading towards those tissues most resistant to remodeling and resorptive changes www.indiandentalacademy.comwww.indiandentalacademy.com
  • 35. 3535 Effective support is realized when, 1) The denture is extended to cover a maximal surface area without impinging on the movable or friable tissues. 2) Those tissues most capable of resisting resorption are selectively loaded during function. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 36. 3636 3) Those tissues most capable of resisting vertical displacement are allowed to make firm contact with denture base during function. 4) Compensation is made for the varying tissue resiliency to provide for uniform denture base movement under function and maintain a harmonious occlusal relationship. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 37. 3737 NATURE OF SUPPORTING TISSUE, • Ideally the soft tissues should be firmly bound to underlying cortical bone, contain a resilient layer of submucosa, and be covered by keratinized mucosa. •The underlying bone should be resistant to pressure induced remodeling. •These characteristics minimize base movement, decrease soft tissue trauma, and reduce long term resorptive changes www.indiandentalacademy.comwww.indiandentalacademy.com
  • 38. 3838 Soft Tissues, •The presence of keratinized firmly bound mucosa permits the tissue to better resist stress. • Keratin is a scleroprotein present in the stratum corneum and is the end product of epithelial degeneration which protects the vital underlying epithelial layers. • Excessive trauma to the mucosa beneath a denture base can lead to abnormal tissue changes such as the development of parakeratin, localized hyperkeratosis and epithelial ulceration or necrosis. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 39. 3939 •The epithelial covering of the hard palate is termed as "masticatory mucosa." It is pale pink and firmly bound to the underlying structures. • Various regions of hard palate differ because of varying structures of submucous layer. • Inspite of the well defined submucous layer in the areas between the palatine raphe and palatine gingiva, the mucosa is immovably attached to the periosteum of the maxillary and palatine bones. Dense bands of fibrous connective tissue join the lamina propria of the mucosa with the periosteum. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 40. 4040 •The submucosal space is filled with adipose tissue in its antero-Jateral portion, and glands in the postero-lateral portion. The presence of fat and glands in the submucosa act as a “hydraulic cushion”. •The mucosa is considered as a structure because its tissue components have individual and collective characteristics. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 41. 4141 The cells comprising the mucosa by their form and arrangement provide a mechanism of defence. It is by their capacity of reproduction and adaptability that cells maintain their individuality. Adaptation to changes in the environment are within the range of normality, provided the changes are not too extreme. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 42. 4242 Hard Tissues, • Another requirement of ideal support is the presence of tissues that are relatively resistant to remodeling and resorptive changes. • Minimizing the pressures in those areas most susceptible and directing the forces towards those regions relatively resistant to resorption can help to maintain healthy residual ridges. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 43. 4343 Bone Factor,Bone Factor, •The generally accepted pressure tension concept appears to play an important role in the destruction or preservation of the bone of the residual ridge. •This concept holds that pressure stimulates resorption and tension maintains the integrity or causes the deposition of bone. •Tension placed on bone, such as that observed in the area of muscle attachment, tends to preserve the quality of bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 44. 4444 • Cortical bone is more resistant to resorption than cancellous or medullary bone. • Regions of muscle fiber and tendinous attachments to cortical plate through sharpey’s fibers ensure tension on bone. • It is therefore a keratinized masticatory mucosa firmly bound to underlying cortical bone through a variable zone of connective tissue and submucosa with associated muscle attachments that provides the ideal denture bearing tissuedenture bearing tissue. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 45. 4545 THE DENTURE BEARING AREAS According to GPT-8, The surfaces of the oral tissues that are available to support a denture are known as denture bearing areas. As Edward Boucher noted “Since the success of complete denture depends largely on the relation of the dentures to anatomic structures which support and limit them, familiarity with the location and character of these structures is essential”. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 46. 4646 Based on clinical and histologic impressions the dentist can categorize the denture bearing tissues into, I. Primary stress bearing areas. 2. Secondary stress bearing areas. 3. Valve producing areas. 4. Relief areas www.indiandentalacademy.comwww.indiandentalacademy.com
  • 47. 4747 Primary Stress Bearing Areas:Primary Stress Bearing Areas: •The primary stress bearing areas are at right angles to occlusal forces and usually do not resorb easily. •This area presents a grayish pink tissue because of its dense character and minimal vascularity. •The external surface of this tissue is the stratum corneum layer. The stratum corneum is usually of moderate thickness and composed of densely packed cells filled with keratin over a dense collagenous submucosa and attached firmly to the underlying bone. •It is the area most tolerant to resulting denture movement and resulting irritation. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 48. 4848 The primary stress bearing areas in maxilla are; - Posterior part of residual alveolar ridgePosterior part of residual alveolar ridge.. - Crest of residual alveolar ridge.- Crest of residual alveolar ridge. -- Flat palatal vault areaFlat palatal vault area www.indiandentalacademy.comwww.indiandentalacademy.com
  • 49. 4949 Flat or Horizontal Part of Palate: • In the maxilla the horizontal portion of the hard palate lateral to the midline raphe should provide primary support for complete dentures. • Keratinised masticatory mucosa overlies a distinct submucous layer everywhere but at the midline suture. •Dense bands of connective tissue traverse the submucosa, firmly binding the lamina propria of the epithelium to the underlying periosteum. •Over the midline raphae the mucosa is unyielding, has little or no submucosa, and must be relieved to avoid tissue impingement between the denture base and bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 50. 5050www.indiandentalacademy.comwww.indiandentalacademy.com
  • 51. 5151 • Clinical observations of patients wearing roofless maxillary denture substantiate the significance of incorporating the hard palate into denture support. • The function of tensor veli and levator palatini muscles of the soft palate may provide the sources of tension that counteract the pressure resorption normally expected beneath a denture base. • In any event, the horizontal hard palate resist resorption and is covered by keratinised mucosa and resilient submucosa. • These properties dictate the essential function as a primary denture support area. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 52. 5252www.indiandentalacademy.comwww.indiandentalacademy.com
  • 53. 5353 Crest of Residual Alveolar Ridge:Crest of Residual Alveolar Ridge: The crest of the maxillary residual alveolar ridge is considered as the primary stress bearing area because; • It has more dense cortical bone and is compact in nature. • The mucosa is firmly attached to the periosteum of the bone and not displaceable. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 54. 5454 The fibrous connective tissue in this region is most favourable for support because of its firmness and position. The stratified squamous epithelium is thickly keratinized. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 55. 5555 •Clinical research has shown that the maxillary alveolar ridge undergoes remodeling changes when subject to the functional stresses transmitted by a tissue borne prosthesis. • Rapid resorption involving the anterior maxillary ridge beneath a complete denture opposed by mandibular anterior natural dentition is frequently seen. • Resorption is usually more rapid when the lower anterior teeth are permitted to contact the maxillary denture without simultaneous posterior contact either in centric relation or during excursive movements. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 56. 5656 Palatal Support:Palatal Support: •The anterior papilla requires a little relief as it is the bony exit for the nasopalatine nerves and blood vessels. • A high or V-shaped palate only provides secondary support. The flat or U-shapedU-shaped palate provides excellent support that should not be lost or diminished with the use of arbitrary heavy foil relief. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 57. 5757 •The shrinkage of resin provides relief, needed or not, over most of the palate. •The arbitrary relief results in an unneeded space that invites the growth of papillary hyperplasia and the accumulation of food, saliva, and debris. Even worse the space often disqualifies the palatal area as a potential source of support. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 58. 5858 Secondary Stress Bearing Areas: •Areas of the edentulous ridge that are greater than at right angles to occlusal forces or are parallel to them; also the areas of the edentulous ridge that are at right angles to the occlusal forces, but tend to resorb under load. •The secondary stress bearing area may appear deeper pink, as compared to the primary stress bearing area, which is apparently due to the increased vascularity. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 59. 5959 The secondary stress bearing areas in the maxilla are •Palatine rugae •Anterior part of residual alveolar ridge. •Slopes of residual alveolar ridge •Maxillary tuberosity www.indiandentalacademy.comwww.indiandentalacademy.com
  • 60. 6060 Palatine Rugae Area: - The rugae are raised areas of dense fibrous connective tissue folds, radiating from the midline in the anterior one third of the palate. The rugae are often compressed or distorted from an ill- fitting denture and should be allowed to return to their normal form prior to impression making. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 61. 6161 Palatine rugae are considered secondary stress bearing area because; • The occlusal forces in the area are at an angle more than 90degree or even parallel. • The connective tissue of the rugae are more resilient and will spring back it’ recorded with pressure during the impression making and cause denture instability. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 62. 6262 •According to Lund, the rugae are not simple elevations of the mucous membrane, but contain as their base a connective tissue nucleus called ruga nucleus. •This consists of a tissue of embryonic character, rich in cells and interwoven with very delicate connective tissue fibres. •The disappearance of the rugae in later life is apparently due to the decrease of submucous adipose tissue, rather than shrinkage of the rugae nucleus www.indiandentalacademy.comwww.indiandentalacademy.com
  • 63. 6363 Anterior Alveolar Ridge:Anterior Alveolar Ridge: Slopes of the alveolar ridgeSlopes of the alveolar ridge:: •The slopes of the residual alveolar ridges are considered as secondary stress bearing areas because these areas are at an angle greater than right angles to occlusal forces or even parallel to them. •The more loosely attached mucous membrane in this region has a non-keratinised or slightly keratinized epithelium and the submucosa contains loose connective tissue and elastic fibres. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 64. 6464 Maxillary tuberosity is considered as secondary stress bearing area because; • The tuberosity is made up of more trabecular bone (spongy bone) and a less amount of cortical bone and hence less favorable for support. • The mucosa covering the tuberosity is thicker and is not firmly attached to the underlying bone resulting in some amount of displaceability. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 65. 6565 • As the surface of the tuberosity is convex it is not at right angles to the occlusal forces and hence not favourable for primary support. • Maxillary tuberosity is more prone for resorption than the crest of the posterior residual alveolar ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 66. 6666www.indiandentalacademy.comwww.indiandentalacademy.com
  • 67. 6767 Mandibular Supporting Structures: Bone of Basal Seat:Bone of Basal Seat: The configuration of theThe configuration of the bone that forms the basal seat for mandibularbone that forms the basal seat for mandibular denture varies considerably with each patient.denture varies considerably with each patient. The mylohyoid ridge may form smooth regular toThe mylohyoid ridge may form smooth regular to bulbous, irregular to severely undercut, thin andbulbous, irregular to severely undercut, thin and sharp.sharp. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 68. 6868 Primary Stress Bearing Areas are decidedare decided depending on,depending on, The occlusal forces are perpendicular to theThe occlusal forces are perpendicular to the surface.surface. More cortical bone, which is quite resistant toMore cortical bone, which is quite resistant to resorption.resorption. The bone is denser and trabecular pattern isThe bone is denser and trabecular pattern is more horizontal.more horizontal. The mucosa is firmly attached to the underlyingThe mucosa is firmly attached to the underlying bone.bone. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 69. 6969 PRIMARY STRESS BEARING AREAS: •Buccal shelf area. •Pear shaped pad. •Posterior alveolar ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 70. 7070 .. Buccal Shelf Area : Anatomically, the buccal shelf area is definedAnatomically, the buccal shelf area is defined as that area of the basal seat located posterioras that area of the basal seat located posterior to the buccal frenum and extends from the crestto the buccal frenum and extends from the crest of the lesser residual ridge to the externalof the lesser residual ridge to the external oblique ridge.oblique ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 71. 7171 BOUNDARIES: anteriorlyanteriorly -- buccal frenum,buccal frenum, posteriorlyposteriorly -- apex of retromolar padapex of retromolar pad,, mediallymedially -- crest of the alveolar ridgecrest of the alveolar ridge laterally -- external oblique ridgeexternal oblique ridge.. It lies between the mandibular buccal frenurnIt lies between the mandibular buccal frenurn and the anterior edge of the masseter muscle.and the anterior edge of the masseter muscle. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 72. 7272 The nature of this bone and the horizontalThe nature of this bone and the horizontal supporting surface provided by the buccal shelfsupporting surface provided by the buccal shelf make it the most suitable primary stress bearingmake it the most suitable primary stress bearing area for the lower denture.area for the lower denture. The horizontal fibres of buccinator muscle allowThe horizontal fibres of buccinator muscle allow the denture to rest on this part of the musclethe denture to rest on this part of the muscle without damage to the muscle or displacementwithout damage to the muscle or displacement of the denture.of the denture. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 73. 7373 The buccal shelf area is the primary support forThe buccal shelf area is the primary support for the mandibular denture, and great care must bethe mandibular denture, and great care must be taken when making the impression to cover thetaken when making the impression to cover the available area in its entirety.available area in its entirety. The buccal shelf can range from 4-6mm wide onThe buccal shelf can range from 4-6mm wide on an average mandible to 2-3mm or less in aan average mandible to 2-3mm or less in a narrow mandiblenarrow mandible •The upward slope of the buccal shelf adjacent to the pad helps resist distal displacement of the denture. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 74. 7474 Importance of Covering the Buccal Shelf: The buccal shelf is the area of bone between theThe buccal shelf is the area of bone between the extraction sites of the molars and the externalextraction sites of the molars and the external oblique line.oblique line. The cortical plate over the site of the extractedThe cortical plate over the site of the extracted teeth is rarely intact and is usually speculated andteeth is rarely intact and is usually speculated and rough.rough. The buccal shelf is intact cortical plate and tendsThe buccal shelf is intact cortical plate and tends not to resorb due to the stimulation of thenot to resorb due to the stimulation of the attachment of the buccinator muscle.attachment of the buccinator muscle. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 75. 7575 When the ridge is flat the buccinator is oftenWhen the ridge is flat the buccinator is often attached almost to the centre of the ridge.attached almost to the centre of the ridge. The buccinator can be covered by the denture inThe buccinator can be covered by the denture in this area because this muscle is relatively flaccidthis area because this muscle is relatively flaccid and inactive,and also its fibres function in aand inactive,and also its fibres function in a horizontal directionhorizontal direction www.indiandentalacademy.comwww.indiandentalacademy.com
  • 76. 7676www.indiandentalacademy.comwww.indiandentalacademy.com
  • 77. 7777 Pear Shaped Pad and Retromolar Pad: Sicher has described the retromolar pad as aSicher has described the retromolar pad as a soft elevation of mucosa that lies distal to thesoft elevation of mucosa that lies distal to the third molar.third molar. It contains loose connective tissue with anIt contains loose connective tissue with an aggregation of mucous glands.aggregation of mucous glands. It is covered by a smoother, less hornifiedIt is covered by a smoother, less hornified epithelium than that seen over the gingivaeepithelium than that seen over the gingivae www.indiandentalacademy.comwww.indiandentalacademy.com
  • 78. 7878 BOUNDARIES: anteriorlyanteriorly - retromolar papilla- retromolar papilla posteriorlyposteriorly - temporalis tendons- temporalis tendons laterallylaterally - buccinator- buccinator mediallymedially - pterygornandibular raphae- pterygornandibular raphae and superior constrictor.and superior constrictor. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 79. 7979 The mucosa of the pear shaped pad is usuallyThe mucosa of the pear shaped pad is usually attached gingiva The termattached gingiva The term ‘pear shaped pad’‘pear shaped pad’ was coined bywas coined by ‘Craddok’‘Craddok’ and refers to the areaand refers to the area formed by the residual scar of the third molarformed by the residual scar of the third molar and the retromolar papilla.and the retromolar papilla. An examination after drying with gauze willAn examination after drying with gauze will reveal that the mucosa is firm, stippled and hasreveal that the mucosa is firm, stippled and has a dull appearance.a dull appearance. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 80. 8080 The retromolar pad is posterior to the retromolarThe retromolar pad is posterior to the retromolar papilla and is shiny, soft and not stippled.papilla and is shiny, soft and not stippled. The pear shaped pad is in line with the residualThe pear shaped pad is in line with the residual ridge and forms its distal termination.ridge and forms its distal termination. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 81. 8181 The mandibular denture should terminate over theThe mandibular denture should terminate over the distal edge of the pear shaped pad.distal edge of the pear shaped pad. If the ridge is poor and the peripheral seal is difficult, itIf the ridge is poor and the peripheral seal is difficult, it may be advantageous to bead the denture just distalmay be advantageous to bead the denture just distal to the pear shaped pad, using ato the pear shaped pad, using a Gritman carverGritman carver. The. The more resilient retromolar pad will usually accept amore resilient retromolar pad will usually accept a conservative seal. The bead should be carved aboutconservative seal. The bead should be carved about 1.5 mm deep and 1.5 mm wide.1.5 mm deep and 1.5 mm wide. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 82. 8282www.indiandentalacademy.comwww.indiandentalacademy.com
  • 83. 8383 The reason the pear shaped pad is so important forThe reason the pear shaped pad is so important for support is because it is an area that rarely resorbs.support is because it is an area that rarely resorbs. This is because the very large and active temporalisThis is because the very large and active temporalis muscle inserts on the coronoid process and also onmuscle inserts on the coronoid process and also on the anterior border of the ramus with the tendonsthe anterior border of the ramus with the tendons ending en the alveolar bone distal to the pad.ending en the alveolar bone distal to the pad. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 84. 8484 The retromolar pad lies at the posterior end of theThe retromolar pad lies at the posterior end of the crest of the lower residual ridge.crest of the lower residual ridge. Histologically, the mucosa of the pad is composed ofHistologically, the mucosa of the pad is composed of a thin, non keratinised epithelium and in addition toa thin, non keratinised epithelium and in addition to loose areolar tissue, its submucosa containsloose areolar tissue, its submucosa contains glandular tissue, fibres of buccinator and superiorglandular tissue, fibres of buccinator and superior constrictor muscles, the pterygomandibular raphae,constrictor muscles, the pterygomandibular raphae, and the terminal part of the tendons of temporalisand the terminal part of the tendons of temporalis musclemuscle www.indiandentalacademy.comwww.indiandentalacademy.com
  • 85. 8585www.indiandentalacademy.comwww.indiandentalacademy.com
  • 86. 8686 The anterior alveolar ridgeThe anterior alveolar ridge, which is bounded, which is bounded distally by the extraction sites of the canines,distally by the extraction sites of the canines, tends to resorb under load and is considered atends to resorb under load and is considered a secondary area of support, when it is flat andsecondary area of support, when it is flat and low.low. Anteriorly if there is severe residual ridgeAnteriorly if there is severe residual ridge resorption when ridge is low, the mentalisresorption when ridge is low, the mentalis muscle and genioglossus and geniohyoidmuscle and genioglossus and geniohyoid muscles come in close proximity with the crest.muscles come in close proximity with the crest. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 87. 8787 In case of ridge resorption, attachments of theIn case of ridge resorption, attachments of the tendons of genioglossus and geniohyoid will be at thetendons of genioglossus and geniohyoid will be at the same level as the residual ridge.same level as the residual ridge. While making the impressions it is important to recordWhile making the impressions it is important to record the muscles in a functional form to prevent thethe muscles in a functional form to prevent the dislodgment of the denture.dislodgment of the denture. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 88. 8888www.indiandentalacademy.comwww.indiandentalacademy.com
  • 89. 8989 Valve Producing Area: The mucosa of the labial buccal vestibule betweenThe mucosa of the labial buccal vestibule between residual alveolar ridge and the lips and cheeks isresidual alveolar ridge and the lips and cheeks is called valve producing area.called valve producing area. The tissues of the oral vestibule and soft palate areThe tissues of the oral vestibule and soft palate are ideally suited to provide a valve seal. The adaptationideally suited to provide a valve seal. The adaptation of the posterior palatine border of the maxillaryof the posterior palatine border of the maxillary denture does not differ from other peripheral contactsdenture does not differ from other peripheral contacts www.indiandentalacademy.comwww.indiandentalacademy.com
  • 90. 9090 The mucosa of the posterior palatal seal area isThe mucosa of the posterior palatal seal area is usually thin and quite elastic.usually thin and quite elastic. It can become a secondary stress bearing area inIt can become a secondary stress bearing area in conditions where the adipose and glandular tissuesconditions where the adipose and glandular tissues of the palate are abnormally reduced in volume.of the palate are abnormally reduced in volume. The thin and inelastic palatine structures must beThe thin and inelastic palatine structures must be protected from stress and strain.protected from stress and strain. The musculature of the valve producing area canThe musculature of the valve producing area can withstand the stresses of mastication adequately.withstand the stresses of mastication adequately. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 91. 9191 RELIEF AREAS: The relief area has a mucosal coveringThe relief area has a mucosal covering considerably reduced in thickness, as comparedconsiderably reduced in thickness, as compared to the primary and secondary stress bearingto the primary and secondary stress bearing areas.areas. The area of the intermaxillary suture or medianThe area of the intermaxillary suture or median raphae presents a rather hard and unyieldingraphae presents a rather hard and unyielding layer of mucosa.layer of mucosa. This area acts as a fulcrum and the dentureThis area acts as a fulcrum and the denture exhibits a tendency to rock from side to side,exhibits a tendency to rock from side to side, because of the lack of tissue resiliency in thebecause of the lack of tissue resiliency in the midline.midline. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 92. 9292 RELIEF AREAS: www.indiandentalacademy.comwww.indiandentalacademy.com
  • 93. 9393www.indiandentalacademy.comwww.indiandentalacademy.com
  • 94. 9494www.indiandentalacademy.comwww.indiandentalacademy.com
  • 95. 9595 Relief regions fall into 3 categories,Relief regions fall into 3 categories, First, tissues that are susceptible to resorptionFirst, tissues that are susceptible to resorption should not be subjected to functional pressures.should not be subjected to functional pressures. These would include some maxillary and mostThese would include some maxillary and most mandibular ridge crestsmandibular ridge crests.. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 96. 9696 Second are those regions having thin mucosaSecond are those regions having thin mucosa directly over hard cortical bone. These includedirectly over hard cortical bone. These include the palatal. midline raphae, tori and exostosisthe palatal. midline raphae, tori and exostosis and the lingual surface of the mandible,and the lingual surface of the mandible, especially the mylohyoid ridge.especially the mylohyoid ridge. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 97. 9797 A third category involves those regions ofA third category involves those regions of mucosa overlying neuromuscular bundles suchmucosa overlying neuromuscular bundles such as the incisive papilla and in some cases, theas the incisive papilla and in some cases, the mental foramen.mental foramen. These should be recorded at rest or relievedThese should be recorded at rest or relieved according to the techniques usedaccording to the techniques used www.indiandentalacademy.comwww.indiandentalacademy.com
  • 98. 9898 Relief of the superficial mental nerve: www.indiandentalacademy.comwww.indiandentalacademy.com
  • 99. 9999 METHODS TO IMPROVE SUPPORT: Non surgical methods Surgical methods www.indiandentalacademy.comwww.indiandentalacademy.com
  • 100. 100100 NON SURGICAL METHODS: Rest for the denture supporting tissues. Occlusal and vertical dimension correction of old prosthesis. Good nutrition. Conditioning of patients musculature. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 101. 101101 SURGICAL METHODS: Surgical removal of pendulous tissues. Surgical reduction of sharp or spiny mandibular ridges. Surgical enlargement of ridge. Flabby ridge. Implants. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 102. 102102 Surgical Removal of Pendulous tissues :: Pendulous tissue is often seen on maxillary anteriorPendulous tissue is often seen on maxillary anterior edges especially when the patient has naturaledges especially when the patient has natural opposing teeth.opposing teeth. When the amount of soft tissue is extensive care isWhen the amount of soft tissue is extensive care is needed to avoid the loss of the labial vestibule.needed to avoid the loss of the labial vestibule. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 103. 103103 Surgical reduction of sharp or spiny mandibular ridge: It is important to place a finger on each side of theIt is important to place a finger on each side of the mandibular ridge and evaluate its width.mandibular ridge and evaluate its width. If the ridge is wide (10 mm or more) surgery can beIf the ridge is wide (10 mm or more) surgery can be considered. Of the ridge is narrow (8 mm or less)considered. Of the ridge is narrow (8 mm or less) surgical intervention is contraindicated.surgical intervention is contraindicated. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 104. 104104www.indiandentalacademy.comwww.indiandentalacademy.com
  • 105. 105105 Surgical enlargement of ridge: The size of the ridge may be increased byThe size of the ridge may be increased by surgical procedures, such as bone grafts, skinsurgical procedures, such as bone grafts, skin grafts, inserts of biomechanical materials andgrafts, inserts of biomechanical materials and vestibuloplastiesvestibuloplasties www.indiandentalacademy.comwww.indiandentalacademy.com
  • 106. 106106 Flabby ridge (Mobile or extremely resilient alveolar ridge) is due tois due to replacement of bone by fibrous tissue. It is seenreplacement of bone by fibrous tissue. It is seen most commonly in the anterior part of themost commonly in the anterior part of the maxilla, particularly when there are remainingmaxilla, particularly when there are remaining anterior teeth in the mandible.anterior teeth in the mandible. Situation with extreme atrophy of the maxillarySituation with extreme atrophy of the maxillary alveolar ridge, flabby ridges should not be totallyalveolar ridge, flabby ridges should not be totally removed because the vestibular area would beremoved because the vestibular area would be eliminated. Indeed the resilient ridge mayeliminated. Indeed the resilient ridge may provide some retention for the denture.provide some retention for the denture. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 107. 107107www.indiandentalacademy.comwww.indiandentalacademy.com
  • 108. 108108 IMPLANTS: The sub periosteal implant denture for the mandibular jaw is now considered a reliable and successful treatment modality, although its use depends on the health of the patient and the contour and the amount of bone that remains. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 109. 109109www.indiandentalacademy.comwww.indiandentalacademy.com
  • 110. 110110www.indiandentalacademy.comwww.indiandentalacademy.com
  • 111. 111111 AGE CHANGES IN SUPPORTING TISSUES: The histologic and physiologic characteristics of theThe histologic and physiologic characteristics of the oral tissues are of primary importance in fullyoral tissues are of primary importance in fully evaluating the changes that may occur.evaluating the changes that may occur. PendletonPendleton stated that the arrangement andstated that the arrangement and distribution of the tissues are uniformly constant,distribution of the tissues are uniformly constant, although their character varies somewhat in differentalthough their character varies somewhat in different persons.persons. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 112. 112112 InIn 1935, Pendleton and Glupker1935, Pendleton and Glupker stated: “the stressstated: “the stress of mastication should be distributed according to theof mastication should be distributed according to the natural characteristics and qualities of adaptabilitynatural characteristics and qualities of adaptability presented by the tissues. The dense fibrous tissuespresented by the tissues. The dense fibrous tissues are suited by nature to bear the greatest burdenare suited by nature to bear the greatest burden during function. The highly vascular tissues must beduring function. The highly vascular tissues must be protected from excessive stresses”protected from excessive stresses” www.indiandentalacademy.comwww.indiandentalacademy.com
  • 113. 113113 According to GysiAccording to Gysi, oral tissues highly stimulated by, oral tissues highly stimulated by intermittent horizontal forces favor the production ofintermittent horizontal forces favor the production of a hornified epithelial surface. Tissues subjected to aa hornified epithelial surface. Tissues subjected to a shearing force, such as the rim of a denture rubbing,shearing force, such as the rim of a denture rubbing, with slight vertical pressure, may elicit a state ofwith slight vertical pressure, may elicit a state of imperfect hornification or parakeratosis. Too muchimperfect hornification or parakeratosis. Too much pressure will incite an inflammatory response.pressure will incite an inflammatory response. GrohsGrohs emphasized the role of mechanical action inemphasized the role of mechanical action in changes of denture-supporting tissues which werechanges of denture-supporting tissues which were produced by pressure from artificial appliancesproduced by pressure from artificial appliances www.indiandentalacademy.comwww.indiandentalacademy.com
  • 114. 114114 The tolerance factor must be considered inThe tolerance factor must be considered in evaluating supporting tissue changes. It has beenevaluating supporting tissue changes. It has been established by Pendleton that certain stressesestablished by Pendleton that certain stresses applied to the oral tissues under some conditionsapplied to the oral tissues under some conditions cannot be tolerated, while under othercannot be tolerated, while under other circumstances they may be borne without response.circumstances they may be borne without response. The form of the maxillary arch is favorable and theThe form of the maxillary arch is favorable and the soft tissues are usually adequate for support andsoft tissues are usually adequate for support and distribution of the stress produced by masticatoiydistribution of the stress produced by masticatoiy function.function. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 115. 115115 Van ThielVan Thiel stated that after complete denturesstated that after complete dentures have been worn for some time, three symptomshave been worn for some time, three symptoms of change, distinct from one another should beof change, distinct from one another should be considered. They include:considered. They include: 1) An adaptation and change in basic shape of1) An adaptation and change in basic shape of the tissues takes place. This is dependent uponthe tissues takes place. This is dependent upon the shape of the contact surfaces under thethe shape of the contact surfaces under the dentures and their relative position to each otherdentures and their relative position to each other the supporting tissues undergo a change in formthe supporting tissues undergo a change in form by unfavorable load on the supporting surfacesby unfavorable load on the supporting surfaces as a result of their disharmonic relation in sizeas a result of their disharmonic relation in size and position.and position. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 116. 116116 2) Typical epithelial changes are thickening and2) Typical epithelial changes are thickening and keratinization, connective tissue reactions are ofkeratinization, connective tissue reactions are of an inflammatory, edematous and also fibrousan inflammatory, edematous and also fibrous nature, and the oral glands undergo congestionnature, and the oral glands undergo congestion and atrophy.and atrophy. 3) The symptoms of Group 3 are very varied and3) The symptoms of Group 3 are very varied and range from small solitary inflammatory spots ...range from small solitary inflammatory spots ... to marked inflammation of the whole of theto marked inflammation of the whole of the mucosa under the denture, especially of themucosa under the denture, especially of the hard palate.hard palate. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 117. 117117 Factors responsible for support: Size and consistency of tissues. Patients general health and resistance. Force developed by supporting muscles. Severity and location of past periodontal diseases. Length of edentulousness. Implants. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 118. 118118 CONCLUSION:CONCLUSION: The knowledge of the structure and theThe knowledge of the structure and the function of the tissues in the immediatefunction of the tissues in the immediate vicinity of the dentures can be used tovicinity of the dentures can be used to determine their logical design and providesdetermine their logical design and provides reasons for and answers to some of thereasons for and answers to some of the difficulties which are encountered indifficulties which are encountered in complete denture construction.complete denture construction. www.indiandentalacademy.comwww.indiandentalacademy.com
  • 119. 119119www.indiandentalacademy.comwww.indiandentalacademy.com
  • 120. 120120 Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.comwww.indiandentalacademy.com

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