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Dental Implant supported maxillo facial prosthesis. /certified fixed orthodontic courses by Indian dental academy


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Dental Implant supported maxillo facial prosthesis. /certified fixed orthodontic courses by Indian dental academy

  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education
  3. 3. CONTENTS Introduction to Maxillofacial Prosthodontics. Etiology of Maxillofacial defects. Introduction to Maxillofacial osseointegration. History of Maxillofacial osseointegration. Differences between oral and Maxillofacial osseointegration. Advantages of Maxillofacial implants over conventional adhesives. Cost effectiveness of Maxillofacial implants. Criteria of success of Maxillofacial osseointegration Success rates of Maxillofacial osseointegration. Patient assessment and selection.
  4. 4. Treatment planning. Surgical technique for placement of Maxillofacial implants. Auricular prosthesis. Ocular prosthesis. Nasal prosthesis. Midfacial prosthesis. Oral prosthesis. Skin response at abutment sites. Osseointegration in irradiated patients. Complications around percutaneous implants. Fallow up and management. Review of literature. References.
  5. 5. INTRODUCTION TO MAXILLOFACIAL PROSTHODONTICS Def : The branch of Prosthodontics concerned with the restoration and/or replacement of the stomatognathic and Maxillofacial structures with prostheses that may or may not be removed on a regular or elective basis.
  6. 6. It can be expected that a facial deformity may have a significant impact on a patient's self image and ability to function and interact socially. The emotional insult and consequent interference with quality of life may be far greater than that might be suggested by either the quantity or nature of the tissue defect. The rehabilitation of these patients with a prosthesis that replaces the missing tissue functionally and esthetically can bring back not just their appearance but also the confidence which is needed to live in a civilized society. w
  7. 7. ETIOLOGY OF MAXILLOFACIAL DEFECTS The etiology of Maxillofacial defects falls into two categories. 1. congenital defects: The microtia and agenesis of ear are associated with several congenital syndromes. Treacher collins, crouzon’s, and Pierre robins are some of the syndromes that are associated with facial deformities, palatal cleft and significant malformation external ear. congenital abnormalities are unlikely to result in complete absence of the eyes or nose.
  8. 8. 2.Acquired defects : Traumatic loss such as vehicle accidents, explosive injuries and gun shot wounds can result in loss of facial structures. The ear and nose are also frequently lost in bite attacks. Surgical removal as a result of oral and facial carcinomas.
  9. 9. Introduction To Maxillofacial Osseointegration For a facial prosthesis to be successful, it must meet criteria of aesthetic acceptability, functional performance, biocompatibility, and longevity. As a result of the problems encountered with adhesive systems, advocacy of the use of mechanical retention has been made. In the past, mechanical retention has involved the engagement of divergent undercuts within the defect or the use of external retention by headbands, elasticized retention, spectacle frames, or other methods.
  10. 10. Frequently, inherent retention within the defect is absent or external forms of retention are unacceptable to the patient. With these historically crude approaches to facial prosthesis retention, it is not surprising that methods of retention continued as a source of debate with little resolution and remained the primary limiting factor to success with prosthetic reconstruction. With the introduction of osseointegrated implants to facial prosthetics, there is an opportunity to provide secure retention of prostheses without jeopardizing the integrity of the skin and underlying tissues or the prosthesis.
  11. 11. History of Maxillofacial Osseointegration • In 1975, Branemark postulated that a skin-penetrating implant should be possible based on the principles of dental Implants. • Following the pioneering work by Branemark and his coworkers, the first clinical trial on skin-penetrating osseointegrated implants was conducted in 1977 at Sahlgren's Hospital in Goteborg, Sweden, where specifically designed implants were placed in the mastoid region to support a bone conduction hearing aid.
  12. 12. • In 1979, the first implants were placed in the mastoid region to retain an auricular prosthesis. • In February 1988, the Bone Anchored Hearing Aid (BAHA) was approved for use within the Swedish health system by the Swedish National Social Welfare Board.
  13. 13. • A conference was held in Goteborg, Sweden, on September 1,1988, to consider bone anchored implants in the head and neck region. A report on this landmark conference was compiled by the Swedish Council on Technology Assessment in Health Care. • This report was the founding document on the introduction of Maxillofacial osseointegration in head and neck reconstruction.
  14. 14. • On January 13, 1995, the food and drug administration provided clearance to Nobel Biocare USA, to market the branemark Maxillofacial implant system. • Since 1986, international conferences on Maxillofacial osseointegration have been convened and reports published from that time have confirmed the efficacy and predictability of Maxillofacial osseointegration.
  15. 15. Historical development of Maxillofacial osseointegration in relation to the development of intraoral osseointegrated implants.
  16. 16. Differences Between Oral and Maxillofacial Rehabilitation Oral cavity Extraoral environment Saliva Air exposure Oral Microflora Skin Microflora Mucosal covering Skin covering plaque Keratin, sebum, sweat, More standardized anatomy Highly variable local anatomy Longer implant lengths Shorter implant lengths Higher loading forces Lesser loading forces Lesser incidence of radiation therapy Higher incidence of radiation therapy Varying aesthetic demands of Highly dependent on Aesthetics. prosthesis With main emphasis on function
  17. 17. Maxillofacial are implant fabricated fixtures from pure titanium. They are available in either 3 mm or 4 mm lengths and with a 5-6 mm diameter flange. The flange facilitates initial stabilization of the implant and prevents undue penetration compartments. into interior
  18. 18. Advantage of Maxillofacial implants over conventional adhesives • Improved retention and stability of prosthesis. • Elimination of occasional skin reactions to adhesives. • Ease and enhanced accuracy of prosthesis placement. • Improved skin hygiene and patient comfort. • Decreased daily maintenance associated with removal and reapplication of adhesives. • Increased longevity of prosthesis. • Enhanced esthetics at the lines of junction between the prosthesis and
  19. 19. Cost effectiveness of Maxillofacial implants Time interval, (yrs) Adhesive Maxillofacial retained osseointegrated implant retained 1 3,056 6,419 5 8,418 7,946 10 15,278 12,748 20 28,518 19,077 Maintenance cost 2,910 2,565 Total Cost 31,428 21,642
  20. 20. Criteria of success of Maxillofacial implants The Swedish Council on Technology assessment in Health Care Jacobson et al. 1) The implants should be 1) Individual unattached immobile, as verified by clinical implants should be immobile examination. when tested clinically. 2) No prolonged symptoms, such as pain, infection, tactile disorders, or nerve damage, should be present in connection with the implants. 2) Individual implant performance should be characterized by the absence of persistent or irreversible signs and Symptoms such as pain, infections, neuropathies, or paresthesia.
  21. 21. 3) Penetrated soft tissue should be free from irritation in at least 85% of the regular outpatient postoperative check ups. 3) Soft tissue reactions around skin-penetrating abutments should be of types 0 (reaction free) or 1 (slight redness, not demanding treatment) in more than 95% of all observations. 4) At least 95% of the temporal bone implants and at least 75% of other extra oral implants should be functional after 5 years. 4) A success rate of 95% in the mastoid process and 90% in the orbital region, in nonirradiated bone tissue, at the end of a 5-year observation period should be a minimum criterion for success.
  22. 22. Success rates of Maxillofacial implants (Non-irradiated) Patients Implants Implants Success treated, Inserted, Integrated, rate, % no. no. no. Sweden 435 767 755 98.4 USA 84 268 253 94.4 Canada 84 186 182 97.8 Total 1,221 1,190 97.5 603
  23. 23. Success rates of Maxillofacial implants (Irradiated) Patients Implants Implants Success treated, Inserted, Integrated, rate, % no. no, no. Sweden 16 57 33 57.9 USA 51 33 64.7 Canada 7 36 34 94.4 Total 144 100 69.4 11 34
  24. 24. Patient assessment and selection Maxillofacial reconstruction based on the principles of osseointegration is always an elective procedure. Because of this, it must be done only under optimum conditions on carefully selected patients for whom the potential benefits have been weighed carefully against the known possible complications and risks. Additionally, patients should be kept fully informed about all aspects of the nature of treatment and be given a realistic view of the likely outcome.
  25. 25. In selecting a patient for a particular reconstructive procedure, attention should be represents the optimum form individual's physical, focused whether it of treatment for an psychological, and personal circumstances and perceived quality of life. Many factors and variables need to be considered carefully, including age, the presence of any disease process, the significance of any previous therapy, alternative available treatments and the patient's own wishes.
  26. 26. Special care should be exercised in evaluating children. In many situations all information regarding the effects of the condition will be gained from the parents, with little or no input from the child. Although the parents concerns are of most important and indeed their whole hearted support for all phases of the rehabilitation is essential, it is vital in all cases to understand the problem from the patient's viewpoint.
  27. 27. EVALUATION OF SYSTEMIC DISEASES. Uncontrolled Diabetes Mellitus: Diabetes patients are predisposed to tissue degeneration and compromised healing with increased risk of infection and vascular complications. Hyperthyroidism: Patients are sensitive to epinephrine used in local anesthetics. When exposed to such catecholamine coupled with stress and tissue damage (implant surgery), an exacerbation of the symptoms of hyperthyroidism may occur (thyrotoxicosis). This is a life threatening condition. The treatment is deferred until a medical and laboratory evaluation confirms control of the disorder.
  28. 28. Adrenal disorders: Patients with a history of adrenal gland disease, whether hyper functioning or hypo functioning, face similar problems related to dentistry and stress. The body is unable to produce increased levels of steroids during stressful situations and cardiovascular collapse may occur. Therefore for patients with known adrenal disorders the physician should be consulted before any implant related treatment. Recent Myocardial Infarction (MI): If surgery is done within 3 months of MI, the risk of another MI is 30%.If within 3 – 6 months, it is 15%. After 12 months the incidence of recurrent MI stabilizes at about 5%.
  29. 29. Hypertension: Essential hypertension is treated with medications, many of which have an impact on implant therapy because of their numerous side effects. These include hypotension, dehydration, sedation, and xerostomia, gingival hyperplasia around teeth and implants and depression. Anxiety greatly affects the blood pressure. Pregnancy: Implant surgery procedures are contraindicated for the pregnant patient. The radiographs or medications that may be needed for implant therapy and the increased stress are being reasons. The elective implant surgical procedure should be postponed till childbirth.
  30. 30. Osteoporosis: The most common disease of bone metabolism the implant dentist will encounter is osteoporosis, an age related disorder characterized by a decrease in bone mass, increased micro architectural deterioration and susceptibility to fractures. This condition is common in post menopausal women. The bone density affects the treatment plan, surgical approach, length of healing and the nature of loading. Hyperparathyroidism: It has been noted that when skeletal depletion occurs as a result of stimulation by the parathyroid gland, alveolar bone may be affected before that of the rib.
  31. 31. Fibrous Dysplasia: A disorder in which fibrous connective tissue replaces areas of normal bone. It is found twice more commonly in women than men and may affect a single bone or multiple bones, twice more commonly in the maxilla than mandible. Implant dentistry is contraindicated in the regions of this disorder. Paget’s disease: A slowly progressive chronic bone disorder where both osteoblasts and osteoclasts are involved, but osteoblastic activity is more predominant. The maxilla is more often involved than the mandible. Oral implants contraindicated in the regions affected by this disorder. are
  32. 32. Multiple myeloma: Plasma cell neoplasm originating in the bone marrow. Usually seen in patients between 40 – 70 years of age. Pathologic fractures usually occur. Paresthesia, swelling, tooth mobility and gingival enlargements are also seen. Implants are contraindicated in these patients. Smoking Habits: Tobacco smoke decreases neutrophil count leading to reduced phagocytic activity. Smoking is also associated with decreased calcium absorption and delayed secondary healing. It also contaminate a bone graft and contribute to early bone loss during initial healing.
  33. 33. Radiation therapy: Disruption of defense mechanisms, compromised Endoosseous vascular system, and localized loss of osseous vitality are the main insults to the tissues while the patient undergoes radiation therapy. With regard to bone, the osteogenic potential of the periosteum is most severely affected. All these conditions can severely limit the prognosis for reconstructive procedures. Such patients may be subjected to osteoradionecrosis and should be treated with caution only after the dentist consults the radiotherapist.
  34. 34. TREATMENT PLANNING Each case must be evaluated on the basis of its own individual requirements; however, a number of fundamental considerations are relevant to all cases. On occasion, bone morphology will not permit ideal configuration of fixtures, and as a result the retentive system may take on a variation of geometric form.
  35. 35. The auricular prosthesis : In congenital cases, developmental remnants in the line of the prosthesis, or anterior to it, must be considered for removal if they are counterproductive to the final result. If practical, they can be reshaped to simulate a tragus to help mask the anterior border of the prosthesis.
  36. 36. • Two flange fixtures are more than adequate to retain the average size prosthetic ear. • Implants are ideally positioned in a semilunar fashion beneath the thickest parts of the ear to provide maximum room for restorative materials with minimal over contouring of the part. • Ventilation slits can be positioned conveniently around the distal periphery of the ear base.
  37. 37. The orbital prosthesis: Preliminary data have indicated a higher failure rate of fixtures in the orbital rim than elsewhere in the cranial skeleton. It is important that fixtures be placed 15 mm or more apart because of the radial geometry of the orbital cavity. Ventilation slits can be placed conveniently at the eyelid conjunctival line angle to minimize condensation and irritation within the defect.
  38. 38.
  39. 39. The nasal prosthesis: The state of the maxillary dentition and presence or absence of anterior teeth can be important diagnostic factors in selecting fixture type, length, and location. Ventilation requirements for nasal prostheses are facilitated via perforations within the artificial nares. Fixture sites for large midfacial defects are dictated by the residual anatomy. The residual zygomatic arches can also be used for the horizontal placement of long fixtures which offer excellent anchorage points.
  40. 40.
  41. 41.
  42. 42. The combination intraoral extraoral prosthesis: Defects requiring this combination type prosthesis involve loss of facial continuity combined with partial or total maxillectomy. They are of surgical or traumatic origin.
  43. 43.
  44. 44. Surgical technique for placement of Maxillofacial implants The first patient treated with a Maxillofacial prosthesis retained on skin-penetrating osseointegrated implants was operated on in 1979. This was a patient who was missing his right external ear as a result of tumor surgery. The surgical technique was based on the intraoral procedure developed by Branemark. Four implants were placed in the mastoid process and allowed to integrate without any load for 3 months. The second stage procedure was performed and skin-penetrating abutments were connected to the implants, and a silicone rubber prosthesis made.
  45. 45. When the technique was Introduced in 1979, four implants were used for the retention of an auricular prosthesis. In some cases there was not room for four, and only three and in some cases only two implants were used for the retention. The two-stage procedure was used until 1988, and one stage procedure started in 1989.
  46. 46. “We noted no higher rate of implant losses in these cases. We also noted some important advantages with the use of only two implants. It was much easier for the patient to clean the implant area, which is important to avoid adverse skin reactions. The skin bridges between the implants were, in cases with four implants, often too narrow and more vulnerable, resulting in a risk of adverse skin reactions”.
  47. 47. One-Stage Surgical Technique for Auricular Implant Placement Implant Site Selection: This must be done before the patient is taken to surgery. The external ear canal is a good landmark. The ideal placement is 18 to 22 mm from the center of the external auditory meatus, and on the left-hand side it is between the 1-0’ and 2-0'clock positions for the upper cranial implant and between the 3:30 and 4:30 positions for the caudal implant. The reason for this is that the implants and the bar construction will then be located underneath the antihelix ridge. This is important to be able to achieve an adequate depth and contour of the prosthesis.
  48. 48.
  49. 49. Marks are made with surgical ink where the implants should be placed, and the area is cleaned and patient is draped in the usual way. The incision line, usually 7 to 10 mm behind the intended implant sites is marked. 10ml of 2 % lidocaine with epinephrine is injected, and the incision is made down to the periosteum. That flap is folded anterior and kept in place with two self-retaining retractors.
  50. 50.
  51. 51. Implant Placement: The positions of the implant sites are checked and marked in the periosteum. In the mastoid tip area the air cells are larger and the cortical shell sometimes is fairly thin. A 6 mm wide incision is made in the periosteum and the drilling with a guide drill is started. During all drilling procedures, generous cooling with saline solution is important.
  52. 52. When the lower implant is in place, the position of the upper implant is selected. The distance between the two implants should be at least 15 to 20 mm. The position of the cranial implant often will be in the temporal bone where the bone in most cases is dense and thicker. The drilling in the cranial site is started with a 3 mm guide drill. If bone is still found in the bottom, a drill that will provide space for a 4mm implant is used.
  53. 53.
  54. 54. It is important to make sure that the whole length of the guide drill has gone down. The reason is that the next drill, which is the spiral drill with a countersink edge, does not cut at the tip. The drills are made of stainless steel and 1,500 to 3,000 rpm is used. The next steps are made at slow speed, 8 to 15 rpm, and with titanium tap.
  55. 55.
  56. 56. The titanium tap is picked up, with the connector placed in the low speed hand piece. The tap is kept over the entrance and the direction checked Adequate is carefully. cooling is used when the tap is removed.
  57. 57. The implant mount is picked up with the fork shaped instrument and the screwdriver. The implant mount is screwed on top of the implant. The implant site is cleaned of soft tissue and bone fragments by flushing with saline and using a blunt dissecting instrument. The implant mount with the implant is picked up with the adapter on the hand piece of the drill and kept over the hole. The direction is checked. With the drill at low speed, the implant is allowed to find its way into the threaded hole using slight pressure.
  58. 58.
  59. 59. When the implant is all the way down, the hand piece is turned slightly counterclockwise to release the implant mount from the connector. It is Important not to tilt the implant mount when disconnecting it from the hand piece. The implant mount is then removed from the implant. It is then covered with the thin skin and sutured in place.
  60. 60. Soft Tissue Management : 1) The immobility of the skin close to the implants relative to the underlying bone and the abutment is very important. This is achieved by making a subcutaneous tissue reduction at the implant site. 2) There should be no hair follicles present in the skin at the Implant site. These two goals can be achieved by reducing the thickness of the flap or by using a split-thickness skin graft.
  61. 61.
  62. 62. Abutment Connection : With a 4mm disposable skin punch, a hole is made immediately over the implant and the abutment is secured to the implant with an internal screw. When the fit is established, the abutment screw is tightened firmly. Healing caps are then attached to the abutments to keep ointment soaked gauze down toward the skin to avoid postoperative hematoma and swelling. The surgical procedure is finished by applying a firm mastoid dressing for 1 day. After this, only a light dressing is needed.
  63. 63.
  64. 64.
  65. 65. Postoperative Care : After 5 to 7 days, the packing and the healing caps are removed and the surgical field is left open. A mild antibiotic ointment is prescribed and the patient is told to use that for a week or two and then just occasionally. Three weeks after operation the patient may start to clean the area with soap and water. The implants are left without any load for 3 months.
  66. 66. Orbital prosthesis Historically, different retentive methods have been used to retain Orbital prostheses. Skin adhesives or double sided tape is capable of adequate retention but may lead to the complications of skin irritation, loss of prosthetic margin integrity, discoloration, and misalignment. Mechanical devices such as eyeglasses are useful, but they have limitations such as having to wear the glasses, and movement of the facial muscles independent of the eyeglass frames. The success rate in orbital bone has ranged from 92% to 100% in nonirradiated patients and 45% to 79% in irradiated ones.
  67. 67. Patient Selection : The majority of patients who have undergone exenteration were been treated for life threatening neoplasms or aggressive infections involving fungus. The exenteration procedure consists of removal of the entire soft tissue contents of the orbit, extra ocular muscles, fat, and periorbita. The remaining orbital volume or depth of the socket, influences the options to offer the patient.
  68. 68.
  69. 69. Total exenteration allows adequate spacing for proper positioning of a prosthesis. A subtotal exenteration or a partially filled orbit restricts the facial prosthesis to being thin, with a less natural appearance. Because the orbital walls are thin, only the superior, lateral, and inferior orbital rims are suitable for osseointegration of titanium implants.
  70. 70. Surgical Procedure : The osseointegration procedure is performed in two stages. In the first stage the titanium implants are placed into the orbital rim and the implants are allowed to bond to bone through osseointegration. The second stage is performed 3 to 4 months later when tissue penetrating abutments are attached to the initial implants.
  71. 71. Stage 1 It can be performed under general or local anesthesia. A skin incision is marked with gentian violet or a marking pen along the orbital rim at the designated locations. The skin incision is made just anterior to the rim, and a flap of skin, muscle, and periosteum is elevated to expose the bony rim. Typically, three to four sites are chosen for implantation, with the superolateral and the inferolateral rim the more frequent sites.
  72. 72. The initial drilling is done with an exploring cutting bur, which produces a small hole. The orientation of this hole should be directed toward the center of the orbit. This allows space for any bridging apparatus used and the future prosthesis. If the bone is adequate, a 3 - 4 mm spiral drill with a countersink is used to form the final hole diameter. Next, the threading of the hole is done with the threading tap. This step is accomplished at the slow speed of 8 to15 rpm that allows the precise cutting of bone needed for proper implant setting.
  73. 73.
  74. 74. • The titanium implant is selected for the hole depth (3 or 4 mm) and screwed into the threaded hole with an implant mount on the drill. • The implant has a cover screw placed that is screwed into the internal threads of the implant. • A topical antibiotic is applied with a pressure dressing. This dressing is removed in 1 week. • If the continuity of the orbital rim is disrupted, several options are available for bony reconstruction to create a bed for implant placement. Common sites for autogenous bone grafts are the calvarial bone, iliac crest, and fibula.
  75. 75.
  76. 76. Stage 2 : This is done after 3 to 4 months. The second stage involves the placement of Titanium abutments and the proper thinning of the skin around them to prevent the movement of skin adjacent to it. This step prevents skin irritation and infection and allows integration of the skin with the abutment. It is usually done under local anesthesia.
  77. 77. A trephine is used to cut an opening over the implant. An abutment is placed through the opening and attached to the implant with an internal screw. The abutment can be 3 or 4 mm in height. The abutment is covered with a healing cap. Antibiotic soaked gauze is wrapped around the abutment to immobilize the skin. Four to five weeks after stage 2, the patient is ready for prosthesis fitting.
  78. 78.
  79. 79. Nasal prosthesis • Throughout the history the nose has been described as the object of beauty and symbol of strength. The amputation of nose has been the bitter price of social dishonor and even the reason for military conflict in the history. • The nasal reconstruction has been credited to Indians. Sushruta in his book “Sushruta Samhita” (600 BC) described the use of a cheek flap for the reconstruction of nasal tip.
  80. 80. In the total nasal defect, there is usually sufficient amount maxillary bone that creates the inferior border of the piriform aperture. If the nasal defect involves only the lower portion of the nose, only two osseointegrated implants inferiorly in the maxilla are enough or further resection of the remaining nose in the upper area is done to expose the nasal bones. For aesthetic reasons, glabella and lateral maxillary sites are poor choices for implants, because framework will interfere with the aesthetic formation of the nose.
  81. 81. Stage I An incision is made and the periosteum and skin are elevated together. The location of the implants is marked, and a 4 mm implant is usually placed in the lower piriform aperture and 4 mm or 3 mm implants in the nasoethmoidal area. It is extremely important to use minimally traumatic technique, low speed drilling, and copious irrigation.
  82. 82. Stage II Approximately 3 months after the first stage, It is preferred to open the old incision and the flaps are thinned and the wound is approximated with a few sutures. The holes for the penetration of the abutments are created with a punch or a scalpel. The cover screws are removed, abutments are placed such that the abutment extends approximately 3 mm above the skin. Healing caps are applied, and a moderately compressive dressing is used to facilitate adherence of the flaps and to limit edema formation. The wound is allowed for 2 weeks to heal before the prosthetic work is started.
  83. 83. Attachments : The decision is made about using a metal bar to connect the abutments for a clip on attachment or using individual magnets. In general, metal bars work better in the area of the nose. The bar has the additional advantage that it limits rotational forces on the implants. once the metal bars or magnets have been placed, the work of attaching the prosthesis can be started.
  84. 84.
  85. 85. Framework Design Framework design must consider: • Space available, including space allowance for retention clip plate or magnet plate; • Length of framework extension from abutments and need for location of cross-bracing stabilization; • Establishment of sufficient airway; • Access for cleaning periabutment tissues and nasal cavity;
  86. 86. • Amount of projection of the framework from the face in the coronal plane; • Facial tissue movement that might affect the fit or retention of the nasal prosthesis; • Ease of prosthesis application and patient capabilities; and • Anticipation of nasal prosthesis mold design.
  87. 87. For nasal prostheses, a midline clip and framework retention is best in most cases. The framework is designed to be cast in metal and is an inverted Y shape that has a cross brace between the widest part of the Y near the abutments. The advantages of this design are that it: 1) Allows maximum bilateral air flow. 2) Provides for vertical and horizontal clip orientation, preventing the misapplication of the facial prosthesis; and 3) Provides adequate access to the nasal cavity and periabutment tissues for hygiene maintenance.
  88. 88.
  89. 89. As part of the wax framework model, plastic sprues 2 mm in diameter are cut and positioned as the vertical stem and transverse brace of the inverted Y. There should be enough space below the cross brace, so that the periabutment tissues can be accessed for hygiene maintenance. Triangular segments of the Y should be as far away from the walls of the nasal cavity as possible, so cleaning of septal surfaces of the internal nose can be accomplished. The stem on the inverted Y should be as short as possible but still allow the attachment of a vertically oriented clip.
  90. 90. Disadvantages of adhesive retained prosthesis. • Adhesive tapes will not stick to the silicone and require daily trimming. They may cause inadvertent margin loss and subsequent unaesthetic thick edges. • The pastes and liquid aromatic cements require daily removal which can cause frictional damage the extrinsic colour of facial surface. • Some patients will also develop allergic reactions to these
  91. 91. • The silicone base adhesives are extremely adhesive on silicone prosthesis but they tend to damage fine margins with daily prosthesis use. • Adhesives may also limit the patients sense of security. • Patients with altered skin sensation may be unaware of loosening or fallen prosthesis. • Some adhesives tend to loose the adhesive bond in regions where perspiration can affect the interface.
  92. 92. MIDFACIAL PROSTHESIS. A 63 year old man, was exposed to repeated surgical procedures over several years, because of a basal cell carcinoma of his face. After 10 years, tumor histology changed into a squamous cell carcinoma. A decision was made to provide him with not only a facial prosthesis but also an implant supported fixed bridge in the maxilla using osseointegrated fixtures. Preoperative examination revealed that the quantity of maxillary bone was not sufficient for a standard procedure, so a bone graft had to be used.
  93. 93.
  94. 94.
  95. 95.
  96. 96. Framework: • The purpose of a fixed framework or substructure is to retain the facial prosthesis. • For retention in this particular case, a bar splint with clips is one alternative to a bar splint with magnets. • Two conventional bar constructions were made, one on the three upper and the other on the three lower maxillary abutments.
  97. 97. A third part of the framework connects the two bar constructions. This part of the construction has an exceptionally long span. Therefore, a Custom made three dimensional framework was prepared. The goal was to achieve stiffness with low weight. These fittings were then soldered to the bar splints and enabled to connect the three parts of the construction. The entire framework was made out of a premachined gold alloy clasp wire 2 mm in diameter, which was bent and soldered to conventional 3 mm gold cylinders.
  98. 98.
  99. 99.
  100. 100. ORAL PROSTHESIS. Hemimaxillectomy: In most defects with surgical resection of a minor or major portion of the maxilla, adjacent bone tissue still allows integration of anchoring fixtures. Careful presurgical prosthetic planning is required, particularly in major defects, in order to evaluate the correct positioning of fixtures and adequate design of the retention framework in relation to expected mechanical load.
  101. 101. Patient presentation 1 A 74 year old woman with a Hemimaxillectomy on left side; there was enough remaining alveolar and basal maxillary bone on the right side to accommodate integrated fixtures. With a connecting bar extending into the defect side, an overdenture obturator could be adequately supported.
  102. 102. Patient presentation 1
  103. 103. Patient presentation 2 If the defect involves both sides, it is quite often difficult to achieve anchorage in the anterior region. It is then important to use not only any remaining posterior portions of the maxilla in combination with bone grafts, but also to install fixtures in the base of the zygomatic bone. A carefully designed metallic framework can then stabilize and retain a denture obturator prosthesis.
  104. 104. Patient presentation 2
  105. 105. Patient presentation 3 If, in addition to the bone defect, the upper lip has also been removed, the soft tissue prosthesis can be retained onto the denture obturator with magnets, as in this case of a 72 year old woman. Bone grafts in both sinuses were used to improve fixture anchorage.
  106. 106. Patient presentation 3
  107. 107. Patient presentation 3
  108. 108. Patient presentation 4 This case shows the rehabilitation of a 20 year old man presented with a major anterior maxillary defect with inadequate bone anchorage of the teeth close to the defect. These were removed, and after an adequate healing time an autologous iliac bone graft was used to substitute for the anterior maxillary segment. Special long fixtures were used to anchor the graft. A long time was allowed for incorporation and fixture integration. A fixed bridge was then connected.
  109. 109. Patient presentation 4
  110. 110. Patient presentation 4
  111. 111. HEMIMANDIBULECTOMY The Hemimandibulectomy is most commonly performed as part of a tumor resection, for the treatment of osteoradionecrosis or occasionally for osteomyelitis. It leaves the patient with multiple problems, as regards to esthetics and function. Because of the loss of bone and teeth the patient cannot chew efficiently, speech is adversely affected, and there is distortion of the facial contours.
  112. 112. These problems are intensified by the displacement of the mandibular fragments that remain, drifting under the unopposed action of those muscles which are still attached to the residual fragments. Shifting of the remaining mandible toward the operated side and malocclusion results.
  113. 113. Diagram showing displacement of mandibular fragments after partial Diagram showing restoration of facial contour by bone graft but persistent dental deficiency. mandibulectomy.
  114. 114.
  115. 115. The following are the advantages of reconstruction using osseointegrated implants: • They provide stability and retention for the prosthesis. • They allow the use of a fixed or removable prosthesis. • It avoids the preparation of remaining teeth as abutments. • It avoids the problems of the tissue borne prosthesis. • It compensates for a diminished denture bearing area. • It provides the stimulus needed for preservation and maintenance of the bone graft. The principal disadvantages are only two. These are the additional cost and the additional surgery.
  116. 116. The abutments need to rise 3 to 4 mm above the surrounding soft tissue to allow for ease of hygiene maintenance. The special problem of salivary incontinence is most likely to appear when, in addition to the resection of the mandible, there has been significant disturbance of the associated soft tissues with loss of sensation and loss of proper muscle control. osseointegrated implants can provide predictable rehabilitation for the hemimandibulectomy patient with both cosmetic and functional success.
  117. 117. THE CLEFTPALATE • Edentulous patients with persistent unilateral or bilateral cleft palate defects may be provided with a bone anchored prosthesis, which not only substitutes for the teeth but also obturates the oronasal communication. • In most cases the available alveolar and basal maxillary bone tissue is adequate in volume and mechanical capacity for fixture anchorage.
  118. 118. Patient presentation 1 A 52 year old man had a cleft palate. When the final remaining tooth was removed he had insufficient retention for his denture obturator. Because of inadequate soft tissue availability, no bone grafting was performed, but each section of the maxilla was provided with three fixtures in the alveolar and basal maxillary bone. After integration, a metallic bar was used to connect the abutments on each side, and a mechanical clip connection was used to anchor the overdenture obturator.
  119. 119. Patient presentation 1
  120. 120. Patient presentation 2 This patient, who was the first cleft patient reconstructed according to the osseointegration procedure, was treated at the Mayo Clinic, Rochester, Minnesota, in collaboration with D. Tolman, E. Keller, and W. Laney. A 69 year old woman with a unilateral cleft which was closed with an iliac bone graft. A bar connects the anchoring elements and provides mechanical retention of the overdenture.
  121. 121. Patient presentation 2
  122. 122. Patient presentation 2
  123. 123. SKIN RESPONSE AT ABUTMENT SITE Skin response to Percutaneus abutments has also been considered as an indicator of success, by rating it on a five point scale. This five point scale is a result of the work of Holgers et al in 1987 and has been adopted widely.
  124. 124. Class Description 0 No irritation: epithelial debris removed if present. 1 Slight redness: temporary local treatment. 2 Red and slightly moist tissue; no granuloma formation: local treatment; extra controls. 3 Reddish and moist; sometimes granulation tissue: revision surgery is indicated. 4 Removal of skin-penetrating implant necessary as a result of infection. R Removal of implant for reasons not related to skin problems.
  125. 125. Grade I – slight redness Grade II - red and slightly moist Grade III - Red and moist Grade IV - INFECTION
  126. 126. The following conditions at skin penetration sites are advocated. 1) Subcutaneous skin reduction; 2) Fixed, Nonmobile skin; and 3) Absence of hair. Brown et al stated: "Fastidious adherence to these principles, will almost always guarantee a favorable skin reaction, but contravention of them will almost as surely result in an unfavorable reaction."
  127. 127. Osseointegration in irradiated patients when the irradiated patients are to be rehabilitated with use of the osseointegration concept, it is necessary to be aware of different factors influencing osseointegration, healing of the soft tissues, and the risk of severe side effects in the compromised tissues. Such side effects include decreased healing rate of the soft tissue over the implants, fistulation, skin or mucosa infections, loss of implants, denuded bone around the implants, and even osteoradionecrosis.
  128. 128. Among the non-irradiated patients, most implants are found non-integrated at the second stage surgery or are lost during the first year. After this time, the remaining implants seem to be relatively well integrated and remain in the bone. The irradiated group of patients has a different course. Most of the implants are lost during the first 3 years, but implants are lost throughout the follow up period; even up to 10 years or more after placement, osseointegration is lost.
  129. 129. Complications In Irradiated Patients Complication Patients, % Loss of implant 35 Slow wound healing 18 Fistula 15 Wound dehiscence 12 Soft-tissue infection 10 Osteoradionecrosis 2 Rupture of major vessel 0 Flap necrosis 0
  130. 130. In a study investigating the possible effects of different irradiation procedures, it was found that radiation dose had a negative effect on the osseointegration process in two ways. First, in the high dose region above 120 Gy a high proportion of implants were lost. Second, in the low dose region, proportionally more implants were lost, whereas osseointegration in the medium dose region showed minor effects. The high frequency of implant losses in the high radiation dose region could be related to the irradiation effect per se, whereas the high losses in the low radiation dose region are more difficult to explain.
  131. 131. The irradiation process induces a progressive endarteritis that becomes more evident with elapsing time. The very low dose irradiation protocols (15-25 Gy) that produced higher implant failures with time are not used in modern radiotherapy. The extremely high dose radiotherapy is only attained in patients with recurrent cancer or new tumor development;
  132. 132. The patients rehabilitated earliest after the radiotherapy course show the highest implant survivals. This has stimulated to perform implant related surgery as soon as possible after tumor removal, and today actually most of the implants are inserted at the time of tumor removal. This has the advantages that the patient is rehabilitated early and implant survival is higher. The negative aspects could be that tumor recurrences might appear during the following years, necessitating more radiotherapy and the removal of the implants at a time of extended tumor removal and other side effect could be the risk of inducing osteoradionecrosis or other complications due to too early surgery in an irradiation field.
  133. 133. Radiotherapy with a metal object in the radiation field induces scattering effects from a radiation beam "bouncing" on the metal framework. These scatter effects depend on the energy and source of irradiation, the distance from the metal to the tissue, and the atomic number of the metal. Possible effects of the increased radiation dose in the delicate interface zone between an implant and the bone or between the abutment and the skin are not completely understood. In certain patients it could be the cause of implant loss and skin reactions, but in other patients it also could stimulate cell turnover.
  134. 134. HYPERBARIC OXYGEN THERAPY The protocol: 20 sessions at 2.5 atmospheric pressure preoperatively and 10 postoperative sessions. The biologic effects that can be measured in an irradiated tissue that has undergone HBO treatment are improved vascularisation, improved bone turnover, and improved metal to bone contact. The target cells influenced by oxygen seem to be undifferentiated mesenchymal cells in the callus or granulation tissue that has the ability to differentiate into osteoblasts. In a healing soft tissue wound, the granulation tissue exposed to hyperoxia will form angioblasts, leading to improved angiogenesis. Both of these factors are important for the osseointegration process, especially in compromised tissue.
  135. 135. COMPLICATIONS AROUND PERCUTANEUS IMPLANTS A Percutaneus implant is a foreign body penetrating the skin through a defect created during surgery. Because the skin barrier is broken, exogenous agents more easily penetrate into the tissue. The following may be important for the function of epithelial penetrations: • A tight contact between the epithelium and the penetrating implant;. No relative Motion in the interface area. • The surface architecture of the implant material; • The status of the connective tissue. and
  136. 136. Marsupialization: The epithelium has a tendency to grow down along the skin penetrating implant to a varying extent, and such an epithelial down growth is a common finding. A total epithelial down growth is one of the failure modes forming a sinus tract along the implant and is due to the free edge effect of the epithelial cells.
  137. 137. Avulsion: The skin around a Percutaneus implant is subjected to forces that lead to mechanical disruption of the interface, with microhematomas and subsequent microfoci of acute inflammation. This is considered to be a mechanically induced failure mode.
  138. 138. Permigration: The health and the maturity of the connective tissue are of great importance for the epidermis. Immature connective tissue cannot nourish the epidermis, which will permigrate deeper down around the skin penetrating implant. This failure mode is related to implants with a porous surface. The soft connective tissue and the epidermis migrate into the implant and continue throughout the entire porous extent of the implant.
  139. 139. Infection: When an infection is established around an implant, it may have serious effects and usually leads to failure of the implant. The major pathogen in infections around metal implants is considered to be Staphylococcus aureus. Coagulase negative staphylococci, in particular Staphylococcus epidermidis, seem to be the most common agent in infections related to implants of polymers.
  140. 140. Delayed Hypersensitivity: Another important reaction, especially for metal implants, is delayed hypersensitivity or contact allergy. This is well known for non skin penetrating implants of nickel, chromium, and cobalt. Reports indicating hypersensitivity to titanium are rare.
  141. 141. Implant Failure: Failure of an implant is the most severe complication. Depending on the number of implants remaining and the design of the retentive mechanism, the prosthesis may need to be modified. If two or more implants remain and the retention design is not compromised, the prosthesis can be stable and retentive. If a bar clip system is used and implant loss means that there is no inadequate support for the bar, then individual magnets or ball or stud attachments need to be used.
  142. 142. FALLOW UP AND MANAGEMENT Once a patient is treated, the osseointegration team has to undertake a lifelong responsibility for the maintenance of the bone anchored prosthesis. Much time and effort are spent in the fabrication of a bone anchored prosthesis that will provide a lifelike facial restoration. For all of its advantages, the bone anchored facial prosthesis does require more care on the patient's part and closer professional follow up than one retained with adhesive.
  143. 143. Follow up management actually begins once the abutments have been placed. After the initial healing period and once a surgical dressing is no longer needed, the patient should be instructed to clean this area on a daily basis. The purpose is to remove cellular material on the skin or abutment, which can come from the interface of the epithelium and abutment. This is performed with a soft end nylon bristle toothbrush, an interproximal dental brush, or a cotton swab. To facilitate cleaning, the area should be moistened first with an even mixture of hydrogen peroxide and water to soften any dried debris.
  144. 144. End tuft tooth brush Interproximal tooth brush Cotton swab
  145. 145. The prosthodontist should monitor the stability of the abutment and the health of the soft tissue during the regularly scheduled visits for prosthesis fabrication. abutment tightness can be checked using a abutment clamp. If the abutment loosens, complete seating should be verified before retightening. This is done with an abutment holder. On the day that the prosthesis is given to the patient, adequate time should be allotted for instructions on placing and removing the prosthesis as well as proper maintenance of the prosthesis, abutments, and surrounding skin areas.
  146. 146. Abutment clamp provides Abutment holder ensures counter torque for checking complete seating of loose abutment tightness. abutment.
  147. 147. When placing the prosthesis, the patient should be certain that the retentive elements are engaged completely to ensure that the prosthesis is seated fully. The retention elements (clips, magnets, or balls or studs) within the acrylic resin plate ensure security of the prosthesis.
  148. 148. The patient should be careful when removing the prosthesis so that the thin margins do not tear and the silicone rubber does not separate from the resin plate. For an auricular or nasal prosthesis, proper removal by grasping a thick portion of the prosthesis and slowly disengaging the retentive elements should be demonstrated and performed several times by the patient. For an orbital prosthesis, an outer margin should be lifted carefully until a thicker portion can be grasped to lift the prosthesis.
  149. 149. Review of literature George E. Anastassov and Eric S. Asher (JPD 2000;84:21516) stated that the soft tissues overlying the percutaneous implants are usually thick and mobile, which requires longer transcutaneous attachments. However these attachments may compromise the stability of the implants and lead to the implant loss. To avoid these complications skin and subcutaneous debulking and split thickness skin grafts should be performed.
  150. 150. Stephen M. Parel. P I Branemark et al states that the application of osseointegrated fixtures to the cranial skeleton facial for prostheses retention marks revolutionary step in search for the perfect soft tissue replacement. They along present Eastover technology to be used to its greatest potential by protecting surface color and allowing long term retention of fine but weak peripheral margins.
  151. 151. Albertson et al conducted 951 clinical observations of skin response around 389 abutments for BAHA(243 observations) and auricular prostheses (708 observations). Of these observations 92.1% showed no skin response and 3.9% showed slight redness, potentially serious skin responses occurred in only 2.8% of observations.
  152. 152. Rubinstein reported that orbital prostheses were fabricated with wider variety of attachments than any other type bone anchored facial prostheses: bar clips, magnets, ball studs, or a combination of these types.
  153. 153. In review of treatment centers Rubenstein found that magnetic retention represented nearly half of the attachments in united states and Canada compared with only one third of those used in Sweden. Clips were used only 20% of the time in united states, 33% of the time in Canada and nearly 50% of the time in Sweden. Approximately 20% of the orbital prostheses in the united states and Sweden used a combination of magnets and clips.
  154. 154. References • Osseointegration in Maxillofacial reconstruction : Per-ingvar branemark, Dan E. Tolman. • Advanced Osseointegration Surgery – application in maxillofacial region: Philip Worthington, Per-ingvar Branemark. • Maxillofacial rehabilitation: Keith F. Thomas.
  155. 155. 1. Craniofacial osseointegration .The canadian experience – Int J Oral maxillofac Implants 1993;8:197-204. 2. Microflora associated with percutaneous craniofacial implants used for the retention of facial prosthesis -Int J Oral maxillofac Implants 1995;10:578-82 3. Console abutment loading in Craniofacial osseointegration -Int J Oral maxillofac Implants 1998;13:245-52. 4. Craniofacial osseointegrated implant induced strain distribution -Int J Oral maxillofac Implants 1997;12;200-10
  156. 156. 5. Biomechanical considerations for implant supported orbital prosthesis –J facial somato prosthet 1995;1:43-53 6. Rehabilitation of irradiated cancer patients with tissue integrated prosthesis: Adjunctive use of hyperbaric oxygen to improve osseointegration- J facial somato prosthet 1996;2:1-11. 7. Use of surgical positioner for bone anchored facial prosthesis –Int .J oralmaxillofac implants 1997;12:376-79.
  157. 157. 8. Use of frontal process of the maxillary bone for implant placement to retain a nasal prosthesis .A clinical report. Int J oral maxillofac implants 2004;19:901-05. 9. Osseointegration in maxillofacial prosthesis part II Extraoral applications Prosthet dent 1986;55:600-06. 10. Bone anchored maxillofacial prosthesis. Quintessence 1989;235 11. Surgical considerations for endoosseous implants in the craniofacial region report. Int J oral maxillofac surg 1993;22:272-77
  158. 158. 12. Diminishing dependence on adhesives for retention of facial prosthesis. J Prosthet dent 1980;43:552 13. The use of magnets in maxillofacial prosthesis. J Prosthet dent 1971;25:334 14. Osseointegrated implants for replacement of absent or defective ear. Clin plast surg.1990;17:355-366. 15. Bone anchored craniofacial prosthesis study. Int J oral maxillofac implants 1996;11:159-68.
  159. 159. THANQ Leader in continuing dental education