Retention in maxillofacial prosthesis copy


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  • In maxillofacial prosthesis there exists the wide variety of types and method for gaining retention , stabilization and immobilization of the prosthesis. The problems of retention of maxillofacial prosthesis should be solved by the prosthodontists. Therefore at the time a prosthesis is designed full consideration must be given to the retention of the prosthesis .
  • Excavation of tombs from this period have provided evidence of the fabrication of nasal ,orbital , auricular prosthesis . Egyptologiest have reported that such prosthetic appliances were inserted after death in order to meet the religious belief that only those without physical defect would enter the kingdom of Osiris.
  • In one variation of this device a dried sponge was attached to the upper surface of the obturators , when the sponge become moist it expanded and held the prosthesis in place . In another variation he used a mechanical button to lock the obturators in place .
  • In one variation of this device a dried sponge was attached to the upper surface of the obturators , when the sponge become moist it expanded and held the prosthesis in place . In another variation he used a mechanical button to lock the obturators in place .
  • Both of these device were held in place by a metal band that went over the head
  • Anatomic undercut areas are a welcome features in the post surgical case .these may be found in the palatal area ,cheek ,retromolar ,labial ,septal posterior pharyngeal or anterior nasal spine areas
  • The support is available from the residual maxilla and from within the defect both must be considered
  • The residual alveolar ridge is important for support in both the dentulous and edentulous patient .
  • Although the floor has broad area for support it usually is not needed because positive support within the defect should be achieved mainly to prevent rotation of the prosthesis into the defect .the patient should use contralateral side for mastication .Pterygoid plate or temporal bone most commonly used region for support of an obturators prosthesis. Positive contact of the prosthesis with bony structures is adequate to tripod the support for an obturators so that rotation of the prosthesis into the defect is minimized. If defect that extends across the midline of the nasal septum become available for support .the nasal septum is poor support for extensive prosthesis coz it is partly cartilage and very little bearing area.
  • Consideration should be given both structures within the residual maxilla as well as to those within the defect that must be relied on to provide adequate prosthesis retention. Both direct and indirect retention are important .
  • The residual soft palate provide the palatal seal so that prevents the passage of food and liquid above the obturators .total surgical removal of the soft palate should be avoided because it creates a clinical situation similar to a congenital cleft palate in which the severity of the defect is increased because a significant protion of the maxillar also has been removed .
  • Anterior extension from the medial portion of the obturators prothesis provides some resistance to vertical displacement of the anterior portion of the prosthesis because this extension competes for insertion and removal with the extension over the soft palate it often must be limited .
  • For adequate surgical closure most large maxillary resections are lined with a split thickness skin graft along the anterior , lateral and post lateral walls of defect. A scar band result after the surgery at the level of mucobuccal fold .this graft will contract but the tissue above this graft tends to stretch crating an area above the scar band that can be engaged by the obturators
  • As with retention and support specific areas of the residual maxilla as well as the defect itself must be considered in minimizing the extend of these potential movement .
  • And provide better seal of the prosthesis with the use of an adhesive eg would be any bony wall of a defect with which part of the prosthetic device will come in contact or a cartilaginous remnant of the ear .
  • The most common method for retaining a prosthesis is a cast metal clasp which enters the undercuts of tooth .
  • Cast circumferential clasp is most commonly used clasp design in all definitive removable partial denture and also in obturators prothesis .
  • Generally wrought wire clasps are used for surgical and interim obturators prosthesis . However they are also used effectively in definitive obturators .
  • Removable partial denture designed for maxillectomy patient are further complicated by the added weight of the obturators . To help compensates for the differences of torque and levers in maxillectomy patient some dentists use retentive surfaces on the lingual aspect of the abutment teeth .
    The prognosis of obturators improves with size and curvature of arch, the quality of the tissue covering the ridge and lining the defect , an abutment alignment that is curved instead of linear, the availability of teeth on the defect side for support and retention .many design require full coverage of the remaining palate for maximum support.
  • Chyes attachment ,chrismani ,Channel shoulder pin system
  • Male portion distal of abutment tooth and female part in denture base ‘
  • Stabilex units ,scot attachment ,
  • They are most commonly classified according to the manner of dispensing and described as double sided tapes, liquid , pastes, and spray adhesive
  • Heptane or ethyl acetate.
  • Patient with poor dexterity or coordination have
  • In 1977 branemark and his coworker installed specifically desighned implants in the mastoid region to support a bone conduction hearing aid , this pioneering work was conducted at sahlgrenska hospital in goteborg sweden.
  • Efficacy of implant support has been established in the restoration of edentulous and partially edentulous jaws ,
  • The bone in the post auricular temporal region superior lateral orbital rim , malar process or superior maxillae are excellent sites for fixture placement with appropriate access ,
  • It is a wire soldered to the gold cylinders and attached to the abutments by gold cylinders and attached to the abutment by gold screws .
    Retentive clips are placed on the inner aspects of the prosthesis .
  • One of the drawbacks of bar and clip system has been that during prothesis construction the bar has to be placed into the mold so there is always the risk ,
  • However in selecting the magnetic systems one must consider daily activities of the patient because an accidental dislodgement of the prosthesis can occur with lateral
  • This system provides security to patient because the prosthesis keeps in position until the system is unlocked.
    However excessive forces applied without disengagement of the system can cause silicone tear and system displacement from acrylic base.
  • However excessive forces applied without disengagement of the system can cause silicone ear tear and system displacement from acrylic
  • Because implants are not evenly distributed .the retentive bar will contain the stainless steel keepers . An acrylic resin section house the magnets possibly a clip for the prosthesis .
  • The temporal bone has sufficient thickness to accept a 3 to 4 mm implant , a minimum of 2 implants are needed ,positioned approximately 18mm from the center of the external auditory meatus and 15 mm from each other .the abutments are joined by a bar constructed in a c shaped design to improve the stability and retention of the prosthesis . The bar can be extended 10 to 15mm beyond the abutment for better distribution of stability and retention .
  • Beyond the abutments for better distribution of stability and retention .
  • The use of a bar and clip system can provide excellent retention for the prosthesis .
  • The advantage of this technique are improved access around the abutment for cleaning and easier concealment of the retention system within the normal contours of the prosthesis, early application of implants for auricle prosthesis . Lack of knowledge concerning the survivability of the shorter implants and the amount of stress applied may have attributed to an excessive number of implants being placed . Currently two implants are considered adequate for the retention of an auricle prosthesis and the supporting of eye glasses.
  • Abutments are connected with bar .the bar can be extended superiorly 10 to 15 mm from the abutment for better distribution of retention for the prosthesis .an acrylic resin is constructed with the prosthesis to house the retentive elements . Retentive clips or magnets can be used
  • A split thickness graft is needed on the sides of the defect to provide a firm no movable foundation for the nasal prosthesis . This procedure will provide room for the prosthesis will reduce the mobility of the tissue bed under the prosthesis and minimize the stress on the implants .the septal cartilage must be surgically reduced surgically anteriorly .this procedure provide
  • Minimum of two implant are required ,positioned in each lateral rounded nasal eminence . Because implants are not evenly distributed and are located and one part of the defect the abutments are connected with a bar. The bar can be extended superiorly 10 to 15mm from the abutments for better distribution of retention for the prosthesis . An acrylic resin section is constructed to house the retentive element .retentive clip or magnets can be used .
  • Tumors requiring maxillary surgical resection  Para nasal sinus, palatal epithelium or from minor salivary glands in submucosa.
  • Alpha sites: 6 mm or more in axial bone volume available.
    E.g. - anterior maxilla through the nasal fossa & the zygoma; zygomatic arch and lateral periorbital region.
    Beta sites: 4-5 mm of bone available.
    E.g. - superior, lateral & inferolateral orbital rims, temporal bone & zygoma.
    Delta sites: marginal sites with 3 mm or less of bone available.
    E.g. - locations in temporal bone, piriform rim, infraorbital rim, zygomatic buttress.
  • The system is surgically implanted and allows sound to be conducted through the bone rather than via the middle ear - a process known as direct bone conduction.
  • The Baha consists of three parts: a titanium implant, an external abutment, and a sound processor. The system works by enhancing natural bone transmission as a pathway for sound to travel to the inner ear, bypassing the external auditory canal and middle ear. Implant & cover screws are made up of pure Ti.
    Flange implants - 3.75 x 3 mm
    - 3.75 x 4 mm
  • That there defects will be less noticeable and their ability to respond to the environment enhanced .as the art and science of this technique evolve however it is anticipated that it will result in the ability to provide improved health care for patients .
  • Retention in maxillofacial prosthesis copy

    1. 1.
    2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
    3. 3. • Contents  Introduction  History  Anatomic retention • Intraoral consideration Support Retention Stability • Extra oral consideration
    4. 4.
    5. 5. Mechanical retention Attachments Adhesives Magnets Implants Conclusion References
    6. 6. • Introduction
    7. 7. HISTORY  2500 B.C EGYPTIAN PERIOD • First historical report of facial prosthetic replacement was attempted during the fourth dynasty 2613/2494 B. C
    8. 8.  200 A .D • In china prosthesis were fabricated in lacquer supported by a specific type of metallic substructures .
    9. 9.  Ambroise Pare • Has given us an excellent description of a simple but very practical obturators for closing a perforation in hard palate .
    10. 10.
    11. 11. • Pare recommended the use of prosthetic nose made up of silver and attached to the face by strings
    12. 12. • He also advocated the use of a prosthesis to replace ear and eye as well .
    13. 13.  Pierre Fauchard • Fauchard designs for a palatal obturators
    14. 14. • The wings are in the shape of propellers which can be folded together while being inserted and spread out after insertion with key .
    15. 15. • In another type the retaining features is in the form of a butterfly wing which is made to open by a key after the closed wings have been inserted through the palatal perforation .
    16. 16. • Another of Fauchard inventions • Is the special spring which he devised for the retention of upper and lower denture . JPD 1965 page 554- 568
    17. 17. • Branemark and his associated first placed modified osseointegrated fixtures in the cranial bone skeletal for the purpose of retaining a prosthetic ear in 1977.
    18. 18. Retention
    19. 19. Anatomic Retention Intraoral consideration Extra oral Consideration
    20. 20. Anatomic retention Intra oral consideration
    21. 21. Anatomic retention • The success of intraoral retention relates to the size and location of the defect and outcome of the surgery.
    22. 22. Anatomic retention Support • Support is the resistance to movement of a prosthesis toward the tissue . • Residual maxilla and within the defect .
    23. 23. Residual maxilla support • Primary area available for support are • Residual teeth • The alveolar ridge • Residual hard palate
    24. 24. • The alveolar ridge support • The size and shape of the ridge should be consider • Large ,broad ridge or the ridge with square or the ovoid provide better support (JPD 1978 vol 39 no 4 424-435)
    25. 25. • Residual hard palate support • Broad flat palate is more conducive to support than the high , tapering palate
    26. 26. With in the defect support Floor of the orbit Bony structures of the Pterygoid plate Anterior surface of temporal bone Nasal septum may used if the defect extends beyond midline
    27. 27. RETENTION • Retention is the resistance to vertical displacement of the prosthesis .  Residual maxilla retention  Alveolar ridge retention
    28. 28. Within the defect retention  Residual soft palate  Residual hard palate  Anterior nasal apertures  Lateral scar band  Height of lateral wall
    29. 29. • Residual soft palate retention  Palatal seal  Extension on superior surface of soft palate is limited by the extend of the defect .
    30. 30. • Residual hard palate  Objective of prosthesis extension is to provide resistance to vertical and horizontal displacement
    31. 31. • Anterior nasal apertures  Entered unilaterally or bilaterally  Depending on the extent of the defect or beyond the midline
    32. 32. • Lateral scar band  skin superior to the junction tends to stretch  creating an area above the scar band that can be engaged by the obturators  Minimized vertical displacement
    33. 33. • Height of lateral wall  In addition to the physical engagement of the floor structures mentioned the lateral wall of the defect can be utilized for indirect retention .
    34. 34. STABILITY  Stability is the resistance of prosthesis displacement by functional forces .  Rotation of prosthesis around the horizontal plane is seen in fulcrum line .
    35. 35. • Anteroposterior • Mediolateral • Rotational • Combination of any or all these direction
    36. 36. • Residual maxilla stability  If natural teeth are present prosthesis framework can prevent the movement in all three direction  In edentulous patient , maximum extension of prosthesis will minimized the movement.
    37. 37. • Within the defect stability  Maximum extension of the prosthesis  Maximum contact with the medial , anterior and lateral walls of the defect
    38. 38. Occlusion  Unstable prosthesis results if the occlusal relationship doesnot maintain intimate prosthesis contact with the supporting and retentive structures.
    40. 40. • This necessitates the use of both hard and soft tissue . • Retention depends on location and size of defects • Tissue mobility or lack of undercuts • Weight of the facial prosthesis
    41. 41. • Hard tissue act as a base against which to seat the prosthesis • Soft tissue prove to be more trouble because of their flexibility , mobility lack of support .
    42. 42. MECHANICAL RETENTION Temporary permanent
    43. 43. • Temporary mechanical retention  Stainless steel wrought wire of 18 gauge size .  some preformed wire clasps can be readily incorporated to acrylic plate of prosthesis.  Preformed stainless steel wire clasps include Adams , arrowhead , Akers or Hawley labial wire
    44. 44. Permanent mechanical retention Cast clasp other forms Circumferential clasp Cast wrought clasp Combination clasp Roach Akers clasp Ring clasp
    45. 45. Permanent mechanical retention Cast clasp other forms Attachments Adhesives Magnets implants Swing lock device Spring Screws Suction cups
    46. 46. CAST CLASP • The clasp extends into an undercut of the supporting tooth in order to gain retention.
    47. 47. Circumferential clasp • Indicated –  class III  Modification space  On the side of the arch opposite a unilateral edentulous space • Contraindicated-  Class I
    48. 48. CAST WROUGHT COMBINATION CIRCUMFERENTIAL CLASP • In 1965 , Dr O.C. Applegate introduced a modified wrought wire clasp assembly known as the combination clasp . • Indicated – class I or class II
    49. 49. Advantages • Has thin light contact • Can flex in all planes • Adjustable • Rigid reciprocal arm can compensates for any orthodontic force applied by the retentive arm
    50. 50. Disadvantages • Tedious lab work • Easily break or distort • Poor stability
    51. 51. T bar cast circumferential combination or Roach Akers clasp • This clasp provides a cervical approach to the tooth surface • Take distobuccal distolabial undercut • Indicated • Unilateral or bilateral distal extension
    52. 52. Contraindicated • When mesial undercuts are presents • It should not be used when height of contour is placed closer to occlusal or incisal surface.
    53. 53. Ring or ring around clasp • Indication  tipped molars • The ring clasp engages undercut by encircling almost entire tooth from its point of origin .
    54. 54. • Disadvantages • Difficult to adjust or repair • Increased tooth surface coverage • Contraindication • If the bracing arm have to cross a soft tissue undercut
    55. 55. • The loss of support of a removable partial denture by a patient who has had a maxillolectomy causes increased pressure , torque and lever action on the associated hard and soft tissue.
    56. 56. ATTACHMENTS
    57. 57. Prefabricated attachments
    58. 58.  Attachments can be placed into cast crowns for the best esthetic and mechanical retention.  Most useful in rehabilitating cleft lip and cleft palate cases .
    59. 59. Intracoronal precision attachment • Advantages • Esthetic • Less bulky • Stable • Less food accumulation • Decreases stresses in abutment
    60. 60. • Disadvantages • Preparation of crown • Complicated procedure • Repair and replacement is difficult
    61. 61. • Examples are
    62. 62. Extracoronal attachments • Indication • Adequate vertical space • Disadvantages • Damages the gingiva distal to distal abutment tooth • Small dead space under the male portion • Not as precise as intracoronal
    63. 63. • Examples are
    64. 64. STUD ATTACHEMENTS • E.g. Dalla bona , Rotherman • Advantages • Easy to adjust • Less leverage • Disadvantages • Cannot be use with limited space
    65. 65. BAR ATTACHMENT • E.g. Dolder and header • Indication • Bone loss around abutment • Advantages • Rigid splinting and • cross arch stabilization
    66. 66. Disadvantages • Difficult to maintain oral hygiene
    67. 67. AUXILLARY ATTACHEMENT  Screw units  Bolts  Frictional devices  Hinged flanges
    68. 68. • First given by Gillette in 1923 • Advantages a)Adaptability to wide variety of clinical situations b)Variations in tooth size & shape accommodated c)Better crown contour in gingival area Semi precision attachment/custom made
    69. 69. DISADVANTAGES: a) Greater lab skill b) Repair & replacement difficult c) Wear resistance less(made of gold alloys)
    70. 70. ADHESIVES
    71. 71. • Adhesive can provide both intraoral and extra oral defects . • they aid in intraoral retention when surgical defect is large • when palate is flat • The anterior posterior lateral septal wall with no undercut .
    72. 72. •Missing tuberosities •Patient with diminished salivary flow due to pre and post radiation therapy. (JPD 1992 68 943-9)
    73. 73. • Most modern prosthetic replacement are secured with adhesives. • All are readily available ,easily applied and can provide satisfactory retention for limited period of time. (JPD 1980 vol 43 no 5)
    74. 74.
    75. 75. Five commonly used adhesive
    76. 76. • Most commonly used adhesive . • Strongest bond with skin . • Care should be taken while using on compromised skin surface . • Can easily removed from skin . • Difficult to remove from silicone Dow corning 355
    77. 77. PSAI and PROS AIDE • Not easily removed from the skin surface
    78. 78. Technique  Apply adhesive 6 to 7mm periphery of the surface  Repeated cleaning might lead to breakage  Not to apply at the edges of the prosthesis to increase the life of the prosthesis
    79. 79. Adhesive remover • Adhesive remover are used to remove adhesive from the skin .e.g. plastic remover , acetone
    80. 80. • Cotton bud is socked in remover and apply slowly under and around the fitting surface of the prosthesis. Technique to remove adhesive
    81. 81. • Some patient may develop allergic and irrigational response . • Poor hygiene may limit the effectiveness of a prosthesis. • Damage external pigmentation. ( JPD 1980 vol 43 no 5 ) Disadvantages of adhesive
    82. 82. • Difficulty in applying the adhesive or adhesive retained prosthesis repeatedly to the proper position.
    83. 83. Sebum – fatty substance release from gland can cause barrier between skin and adhesive . Moisture – can affect the action of adhesive Hair- prevent adhesive layer contacting skin . Solvent – continue use of removal solvent can be allergic to skin Problem with adhesive
    84. 84. To be continued…………
    85. 85. MAGNETS
    86. 86. History • Magnets in maxillofacial Prosthesis have been used for decades to reconstruct large defect .
    87. 87. • Federick rehabilitated a patient with large orofacial defect using a 2-component obturator that was locked to each other with the help of magnets.
    88. 88. • advances in technology have made avail-able a new family of magnetic alloys based on cobalt and other rare earth metals. • They are small but strong and can be used for dental purposes for retention.
    89. 89. • The mutual attraction of unlike poles has been utilized successfully to assemble multicomponent, maxillofa-cial prostheses and even sectional dentures
    90. 90. • Magnets were first introduced for applications in dentistry in the year 1953 in the field of orthodontics.
    91. 91. • 1960 as retentive devices for over dentures, removable partial dentures, and maxillofacial prostheses.
    92. 92. • Magnets is the most efficient means of providing combined prostheses with retention and stability in patient with deformities requiring complex defect . • Majority of prosthesis with magnets are sectioned and have a magnet in each section .
    93. 93. • When section are assemble properly • Magnets are attracted to each other and retain the section ( The Journal of Contemporary Dental Practice Vol 8 No 7 2007)
    94. 94.
    95. 95.
    96. 96.
    97. 97. • Ease of placement • easy replacement • small size with strong attractive forces • Ease of cleaning • Can be used with implant supported prosthesis • They can be embedded on thin sections of acrylic Advantages of magnets
    98. 98. • Tissue undercuts can be used for additional retention of prosthesis . ( JPD 1984 VOL 52 NO 4 page 556-558)
    99. 99. • Low corrosion resistance • High cost • Cytotoxic effect Disadvantages of magnets
    100. 100.  The challenge in magnets as retentive elements in MFP depends on ability to resist corrosion  The development of samarium iron nitride as magnetizeable material may offer better corrosion resistance  use of magnets in prosthodontics may be viewed with much interest in future
    102. 102. History • In 1975 Branemark considered that skin penetration implant may be possible . • In 1977 Branemark and his coworkers Installed specifically designed Implants • in the mastoid region.
    103. 103. • In 1979 these same workers placed the first implants in the mastoid region to retain an auricular prosthesis . • Since these developments , craniofacial osseointegration has become an accepted part of head and neck reconstruction.
    104. 104. • Implants are placed into the residual bone and then used for retention , support and stability of a prosthesis . • The use of similar implants in extra oral site is growing popularity .
    105. 105. • Osseointegration technology offers the first real promise for overcoming the disadvantages of adhesive in the appropriate patient . ( JPD 1988 VOL 55 NO 5 page 600-605)
    106. 106. Indication  Extra oral implants are used for retaining eye , ear and nose maxillofacial prosthesis .  Patient with cartilaginous or peripheral tissue or thick layer of skin .
    107. 107. Contraindication • Poor immune defense • Use of steroids • Neoplasm as a result of chemotherapy • Uncontrolled endocrinopathy
    108. 108. • Relative contraindication • Diabetes mellitus • Irradiated bone or ongoing radiotherapy • Inflammation of implant site
    109. 109. Retention system in extra oral implant • Osseointegration implants in craniofacial reconstruction improves prostheses retention , stability , comfort and safety for a patient .
    110. 110.
    111. 111. Bar clip attachment  Most commonly used  metallic bar clip system present expensive laboratorial procedure
    112. 112. • Advantages  Good load distribution on the implants. • Disadvantages  risk of damaging the bar during construction of prosthesis ( JPD 1996 vol 76 page 603)
    113. 113. Magnet systems  Consists of a magnet cap that is threaded onto the abutment and a magnet is placed onto the tissue surface of the prosthesis.
    114. 114. Indicated  When abutment are not parallel  In orbital and auricular prosthesis with or without bar clip system  Swallow defects with insufficient space for a bar and clip attachment .
    115. 115. • Advantages • Ease of removing and inserting • Makes the wearing and daily care beneficial • Easy hygiene control • Reduce probability of infection
    116. 116. Ball attachment system  Three implants creating a tripod  Provide satisfactory retention and stability
    117. 117. • Indication • Shallow defects as they occupy less space behind the prosthesis .
    118. 118. • Advantages of ball system • Induces less stress to implant • Absence of bar optimizes more hygiene • Provides freedom of movement • Disadvantages • Wear of the rubber ring
    119. 119. Slant lock system • Based on active engagement
    120. 120. • System provides security to patient because the prosthesis keeps in position until the system is unlocked . • Disadvantages • Silicone tear
    121. 121.
    122. 122. • Implant for orbital prosthesis • Superior , lateral , and inferior rims are possible site for implant • 3 to 4mm implants are needed
    123. 123. • For the large defect it is best to connect the abutment with a bar . ( JPD 1993 70 329-332)
    124. 124.
    125. 125.
    126. 126.
    127. 127. Auricular defect
    128. 128.  Bar can be extended 10 to15mm  Two retention system are used gold alloy bar , and magnets
    129. 129.  In gold bar system 2mm gold cylinder is attached to the abutment . retention clip system incorporated into prosthesis providing attachment to the bar .
    130. 130.  Excellent retention for the prosthesis .  However it may limit the access for performing hygiene procedures , require extension of the base of the prosthesis to cover the bar .
    131. 131. • Second retention technique is use of magnets . • Magnets are connected to abutment. • 6mm diameter and 2mm thickness . • The bar structure must be designed to contain housings to hold magnets • Corresponding magnets are placed within the silicone prosthesis .
    132. 132. • Alternative technique employed only the use of magnets • This technique employs a magnet keeper that connects directly to the abutment thus elimination the need for a retaining bar .
    133. 133.
    134. 134. Nasal defects  Implant can be placed in maxillary or frontal bone  4mm implant s are required  Positioned in each lateral rounded nasal eminence
    135. 135. • The prosthesis is completed before the placement of implant . • Position of the abutments and the retentive elements do not compromise the contours of the prosthesis
    136. 136. • Split thickness graft is needed . • The septal cartilage must be reduced surgically • Provide room for the prosthesis to engage the lateral walls of the defect • Increase stability of prosthesis
    137. 137.
    138. 138. Implant design for maxillectomy defect • Prosthetic rehabilitation  close oral & nasal cavities, substitute teeth and anterior soft tissues of the face. • Anchorage - skeletal components are removed - zygoma & pterygoid region used
    139. 139.
    140. 140. Implant design for midfacial defect • Midfacial defects often result from ablative procedures used to control malignancies of nasal & maxillary structures. • As the size of defect increases, complexity of prosthetic rehabilitation increases.
    141. 141.  Jenson DT et al (1992): • Described available sites for the implant placement in the midfacial region • Suggested craniofacial site classification for the osseointegrated implants – alpha, beta & delta sites
    142. 142.
    144. 144. • The Baha is a surgically implantable system for treatment of hearing loss that works through direct bone conduction
    145. 145. Indication • chronic ear infections, • congenital external auditory canal Artesia • single sided deafness who cannot benefit from conventional hearing aids
    146. 146. The Baha
    147. 147. • The titanium implant is placed during a short surgical procedure and over time naturally integrates with the skull bone
    148. 148. • One stage surgical procedure ↓LA. • Placement of Ti implant & abutment in mastoid cortex. • Maintenance of hair free area around the abutment is required. • After osseointegration, abutment is loaded with the mechano-electric transducer system.
    149. 149. • For hearing, the sound processor transmits sound vibrations through the external abutment to the titanium implant. • The vibrating implant sets up vibrations within the skull and inner ear that finally stimulate the nerve fibers of the inner ear, allowing hearing.
    150. 150.
    151. 151. Advantages of implants • Aesthetic is better • Implant simplify the cleaning procedures • Life of prosthesis is long • Implant retained prosthesis have provided the opportunity to participate in routine activities . • Provide ability to function in society with confidence DCNA 1998 vol 42 num
    152. 152. Other types • Screws, swing lock device, suction cups surgical sutures, spectacles etc……..
    153. 153. • Conclusion
    154. 154. • References • Varoujan A Chalian , Joe B Drane ,S Miles Standish Maxillofacial prosthetics • Beumer J, Curtis TA ,Firtell DN Maxillofacial Rehabilitation • HAROLD PRISKEL, Precision attachment in prosthodontics • JPD 1978 vol 39 no 4 ,424-435
    155. 155. • JPD 1992 vol 68 , 934-949 • JPD 1980 vol 43 , • JPD 1984 vol 52 no 4 556-558 • JPD 1984 vol 55 no 5 600- 605 • JPD 1996 vol 76 603 • JPD 1993 vol 70 329-332 • The journal of contemporary dental practice vol 8 no 7 2007
    156. 156. • JPD 1965 page 554- 568 • DCNA 1998 vol 42 num 1
    157. 157.