prosthodontic management of acquired defects of mandible /certified fixed orthodontic courses by Indian dental academy


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prosthodontic management of acquired defects of mandible /certified fixed orthodontic courses by Indian dental academy

  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. Table of content • • • • • Introduction Review of literature Definitions Classification of mandibular defects Physiology of oral function following resection • Diagnostic Consideration for Prosthodontic rehabilitation
  4. 4. • Prosthodontic management Mandibular guidance prosthesis Partially edentulous patient Completely edentulous patient • Role of implants in rehabilitation • Summary • Conclusion
  5. 5. Partially edentulous patient • Lateral discontinuity defect • Anterior continuity defect • Lateral continuity defect
  6. 6. Lateral discontinuity defect
  7. 7. Impression • Preliminary impression are made with modified stock tray. • Cast poured • Surveyed • RPD design
  8. 8. Partial denture design All principles of designing a conventional partial denture should be followed. • Major connector- rigid • Occlusal rest- direct forces along long axis • Direct retainer- engage several teeth
  9. 9. Factors To consider • Closure is angular rather than vertical • Forces of occlusion confined to unresected side • fulcrum line difficult to determine due to frontal plane rotation making it difficult to predict movement pattern of prosthesis during function
  10. 10. Forces of occlusion Frontal plane rotation
  11. 11.
  12. 12.
  13. 13.
  14. 14. • Once framework is fabricated it is tried in the patient’s mouth
  15. 15. Altered cast impression • Altered cast impression of edentulous area is taken • Special care on lingual extension of unresected side should be taken as it provides additional retention and stability • Maximum soft tissue coverage • Coverage of buccal shelf on unresected side is important
  16. 16. • On resected side tissue bed is unyielding hence to mold this area manipulate the cheek and ask patient to move tongue from side to side. • After altered cast impression is obtained, master cast is segmented. • Impression placed on the sectioned cast, boxed and poured
  17. 17. • Occlusal rim are made. • Jaw relation recorded by softening the wax and gently guiding the mandible. • Excessive force to be avoided
  18. 18. • Select teeth depending on opposing dentition • After jaw relation are verified at try-in, denture is acrylized • Partial denture is delivered
  19. 19. Defect with mandibular continuity maintained or reestablished
  20. 20. Anterior defect
  21. 21. • These patients have posterior teeth and extensive edentulous area anteriorly creating a kennedy classIV situation. • Normal mandibular movement pattern • Following bony recostruction vestibuloplasty are indicated
  22. 22. • Design must consider movement of anterior segment of prosthesis • Long mesial rest on 2nd molar provide indirect retention. • Care taken to relieve proximal plate and distal aspect of minor connector to allow for expected movement of prosthesis
  23. 23.
  24. 24.
  25. 25. • Conventional RPD enhance aesthetic and provide lip support leading to improved articulation of speech and salivary control • In small defects mastication is restored • In larger defects mastication is compromised because of length and movement of anterior edentulous span hence RPD serves mainly for lip support
  26. 26. Lateral defect
  27. 27. • Lateral defects in which posterior dentition remains only on one side are difficult to design. • Long lever arm and compromised tissue bed on resected side cause excessive movement of the prosthesis.
  28. 28. Favorable edentulous extension
  29. 29. Unfavorable edentulous extension
  30. 30.
  31. 31.
  32. 32. Completely edentulous patient Compromising factors • Stability, retention, support reduced due to resection • Radiotherapy makes mucosa fragile and atrophic • Reduced saliva with altered quality compromises retention
  33. 33. • Angular pathway of closure induces lateral forces on denture which tend to dislodge • Deviation creates abnormal jaw relation and teeth placement difficult • Impairment of motor and sensory function impair ability to control prosthesis.
  34. 34. • Primary impression made with irreversible hydrocolloid in a modified stock tray • Particular attention must be paid in recording areas posterior to the resection.
  35. 35.
  36. 36. Swallowing impression technique
  37. 37.
  38. 38. Area supported by bone and free of muscular activity drawn on diagnostic cast
  39. 39. • Perforated acrylic resin tray constructed on outlined area • Modeling compound stops placed on impression surface for stability and to provide space for impression material. • Two lateral columns that extend towards the maxillary ridge are formed on tray
  40. 40.
  41. 41.
  42. 42.
  43. 43.
  44. 44.
  45. 45.
  46. 46.
  47. 47. Conventional technique • Border molding and secondary impression can also be used
  48. 48. Maxillomandibular relation recording • Acrylic resin base fabricated on this cast indicates zone of neutralization • Wax occlusal rim placed within this zone • Maxillary rim adjusted for lip support and occlusal plane • Maxillary rim wider on unresected side to account for deviation of mandible
  49. 49. • Lower rim adjusted till a tentative occlusal vertical dmension has been established. • Vertical dimension of occlusion should be closed as much as possible in patient with reduced tongue bulk or mobility to allow tongue to interact with palatal structure • Mandible guided by clinician into unstrained repeatable position for centric registration • Maxillary ramp may be made at this stage
  50. 50. • Retention achieved by close adaptation of the prosthesis with bearing surface and maximal extension of lingual flange on unresected side as compatible with anatomical limitation • Support obtained from buccal shelf, crest of ridge retromolar pad and soft tissue bed posterior to resection
  51. 51. Teeth arrangement Non- anatomic teeth to be used • Abnormal jaw relation • Angular path of closure • Increased lateral stress • teeth arranged within the neutral zone
  52. 52. • Due to deviation and retrusion maxillary anterior teeth are placed lingual to and mandibular anterior teeth are paced labial to normal position.
  53. 53. Mandibular posterior teeth • Posterior teeth on unresected side placed buccal to crest of ridge. • With the lingual inclination of residual mandible and elevation of buccal shelf, placing posterior teeth buccaly centers he forces more favorably on supporting tissue and also is compatible with tongue position.
  54. 54.
  55. 55. On the resected side posterior teeth are placed lingual to the crest as • Lips and cheeks pulled medially due to scarring • To facilitate occlusal relationship with maxilla
  56. 56. Resected side, lingual placement of teeth Unresected side, buccal placement of teeth
  57. 57. Functionally generated palatal ramp • Soft occlusal wax is added on to the posterior and palatal surface of maxillary rim. • Mandible guided through opening and closing movement
  58. 58.
  59. 59.
  60. 60.
  61. 61. Maxillary posterior teeth • Maxillary posterior teeth are placed lingualy on unresected side and buccaly on resected side for favorable occlusal relation • Maxillary palatal ramp can be fabricated at this stage
  62. 62.
  63. 63.
  64. 64. • Following try- in prosthesis is processed in conventional manner. • At the time of insertion disclosing agent should be used to relieve area of excessive tissue displacement.
  65. 65.
  66. 66.
  67. 67.
  68. 68.
  69. 69. • “ Mastication is confined to non-defect side and bilateral occlusal contact serve more as stabilizing force. As muscles of mastication are no longer present on resected side bilateral balance of complete dentures during function in the classical sense is not possible.” Beumer
  70. 70. Role of Implants in rehabilitation
  71. 71. Application of implants has offered a major improvement in management of mandibular resection cases. By providing a foundation onto which fixed prosthodontic treatment is based or for retention of removable prosthesis, implants play a role in making rehabilitative efforts functional rather than mere aesthetic.
  72. 72. The patient receives a stable fixed prosthesis with an appropriate interocclusal relationship and occlusal scheme, predetermined by the guidance-positioning device. The fixed prosthesis resolves the problems, reduces mechanical irritation to the tongue and soft tissue, and allows sufficient space for the tongue for efficient mastication.
  73. 73. PERI-IMPLANT SOFT TISSUE CONSIDERATIONS • Implant abutments that traverse thick, movable, soft tissue beds before entering the oral cavity, frequently are plagued with soft tissue maintenance problems. The cause of these problems is often related to tissue movement, plaque accumulation, and ineffective oral hygiene efforts. • These factors can affect peri-implant health and possibly long-term retention of the implant.
  74. 74.
  75. 75. TIMING OF IMPLANT PLACEMENT Placement of osseointegrated implants at the time of surgical resection and osseous reconstruction has been reported and promoted on the basis of eliminating a separate surgical sitting, avoiding the need for hyperbaric oxygen, and reducing delays in prosthetic rehabilitation. However, this approach frequently results in compromised implant position and orientation limiting optimal prosthetic rehabilitation.
  76. 76. A better appreciation for tumor prognosis after definitive (permanent section) microscopic evaluation of surgical margins, neck node status lifestyle (alcohol, tobacco, other drug abuse) of the patient, and compliance for follow-up evaluations are all important factors to consider and are usually
  77. 77. more predictable and apparent when implant placement is performed in a delayed manner. Even if indicated, it would be imprudent from an oncologic standpoint to place implants when tumor prognosis is poor and risk for recurrence is high.
  78. 78. Osteoradionecrosis is the primary concern after invasive procedures, such as placement of endosseous implants in irradiated bone. Evidence suggests that placement of an endosseous dental implant into irradiated mandibles does not compromise implant integration nor reduce survival rate.
  79. 79. Implants placed in irradiated mandibles show a very high survival rate. Histologic examination confirms implant osseointegration in irradiated bone. A minimal interval of 9 to 12 months between radiotherapy and implant placement is recommended.
  80. 80. Implant supported overdenture
  81. 81.
  82. 82.
  83. 83.
  84. 84.
  85. 85. Implant supported removable partial denture
  86. 86. Arrangement of artificial teeth in the neutral zone after surgical reconstruction of the mandible
  87. 87.
  88. 88.
  89. 89.
  90. 90.
  91. 91. Summary • Rehabilitation of acquired mandibular defect is a challenging task. Several problems are encountered during the rehabilitation.
  92. 92. Physiologic impairment Degglutition Salivary control Speech Mandibular movement Psychologic factors
  93. 93. Diagnostic Consideration for Prosthodontic rehabilitation Location and extent of mandibular defect Presence of remaining natural teeth Rotation and deviation of mandible
  94. 94. • Often with lateral resection, frontal plane rotation, deviation to the resected side is seen. Hence guidance prosthesis is the starting point to rehabilitation. Once appropriate occlusal relationship can be achieved final removable or fixed prosthesis can be fabricated
  95. 95. Partially edentulous patient Lateral discontinuity defect Anterior continuity defect Lateral continuity defect
  96. 96. • For completely edentulous patient the swallowing technique for impression recording, to record neutral zone is recommended. Placement of teeth in neutral zone stabilizes the prosthesis. • Use of implants in management of these cases greatly enhances the functional outcome. The number, location and time of placement are important.
  97. 97. Conclusion Patients operated on for malignant tumors of the mandible, present a far more difficult rehabilitation problem, than those patients with maxillary defects. Recently, advances in the reconstruction of such defects by means of microvascular free flaps have allowed the maxillofacial prosthodontist to rehabilitate these patients more effectively.
  98. 98. With proper multidisciplinary pretreatment planning and postoperative treatment, osseointegrated implants can be strategically placed in those patients with a reconstructed mandible to restore occlusal and masticatory function while also achieving an acceptable esthetic.
  99. 99. Reference • Canter, R. and Curtis, T. A. Prosthetic management of the edentulous mandibulectomy patient. Part II Clinical procedures. J Prosthet Dent 25:546-555, 1971. • Canter, R. and Curtis, T. A. Prosthetic management of the edentulous mandibulectomy patient. Part III Clinical evaluation. J Prosthet Dent 25:670-678, 1971. • Curtis, T. A. and Canter, R. The forgotten patient in maxillofacial prosthetics. J Prosthet Dent 31:662-680, 1974.
  100. 100. • Firtell, D. N. and Curtis, T. A. Removable partial denture design for the mandibular resection patient. J Prosthet Dent 48:437-443, 1982. • Moore, D. J. and Mitchell, D. L. Rehabilitating dentulous hemimandibulectomy patients. J Prosthet Dent 35:202206, 1976. • Desjardins, R. P. Occlusal considerations for the partial mandibulectomy patient. J Prosthet Dent 41:308-315, 1979. • Beumer, J., III, Curtis, T. A. and Firtell, D. N. Maxillofacial Rehabilitation: Prosthetic and Surgical Considerations. C. V. Mosby, St. Louis, 1979
  101. 101. • Prosthetic treatment of maxillofacial injuries • JPD 1955: Lt Colonel Edwin • Prosthetic reconstruction of a resected mandible JPD 1962: Adisman • Use of a guide plane for maintaining the residual fragment in partial or hemimandibulectomy JPD 1964: Robinson and Rubright • Prosthetic mandible of resected edentulous mandible JPD 1969: Swoope
  102. 102. • Rehabilitation of an irradiated mandible after mandibular resection using implant/toothsupported fixed prosthesis: a clinical report. BArak et al JPD 2004: 91:310 • Arrangement of artificial teeth in the neutral zone after surgical reconstruction of the mandible: A clinical report. Kokubo et al JPD 2002:88:125-7 • Titanium osseointegrated implants combined with hyperbaric oxygen therapy in previously irradiated mandibles. Arcuri et al JPD 1997;77:177-83
  103. 103. • Functional criteria for mandibular implant placement post resection and reconstruction for cancer Marunik and Roumanas JPD 1999;82:107-13. • The fabrication of cast metal guidance flange prostheses for a patient with segmental mandibulectomy: A clinical report Aslan et al JPD 2005;93:217-20 • Clinical maxillofacial prosthetics: Thomas Taylor: quintessence pub.
  104. 104. Thank you Leader in continuing dental education