Obturators

Seminar including various important points and studies, which are very important for prosthodontist.

1. PRESENTED BY - Dr Priya Gupta [II MDS] Obturators

2. Introduction Maxillofacial defects Functions of obturators Classification of maxillary defects Pre operative evaluation Biomechanics Types of obturators Design considerations Impression Procedures Hollow bulb obturator Conclusion References CONTENTS

3. “Maxillfacial prosthodontics” is the branch of prosthodontics concerned with the restoration and / or replacement of the stomatognathic and craniofacial structures with a prostheses that may or may not be removed on a regular or elective basis.

4. Most common intraoral defects  maxilla, resulting from congenital malformations and acquired defects due to surgery for oral neoplasms, trauma, disease, pathological changes, radiation burns. Chalian’s Classification : There are three types of maxillofacial defects. 1) Congenital – Cleft palate - Cleft lip - Facial cleft - Missing ear - Prognathism 2) Acquired - Accidents - Surgery - Pathology 3) Development - Prognathism - Retrognathism

5. So a definite restoration is needed to replace missing teeth, to stabilize and align the arch segment, restore the occlusal function, provide facial support and helps in speech in such defects. All this is usually aided with the help of an OBTURATOR. An obturator ( latin : obturare , to seal/ to shut off) It is a disc or plate, natural or artificial, which closes an opening or defect of the maxilla as a result of a cleft palate or partial or total removal of maxilla for a tumour mass. ( Chalian 1971).

6. Ambroise Pare (1541) : First person to close a defect. Pare had given description of a simple obturator for closing a perforation of the hard palate. a dry sponge was attached to the upper surface of the disc. (When the sponge becomes moist by secretion, it expands and hold the prosthesis in place.) In another variation he used turnbuckle type of mechanism to hold the prosthesis. HISTORICAL REVIEW J Prosthet Dent 2003;89;608-610

7. Pierre Fouchard (1728) : One of the types has a wing in the shape of propellers which can be folded together while being inserted and spread out after insertion with a special key. In the other type, the retaining feature is in the form of a butterfly wings which are made to open by a key after the closed wings have been inserted through the palatal perforation.

8. Sueresen (1867) suggested rigid fixed obturator using a wire loop posterior extension; shaped by use of warm gutta-percha. William Morton (1869) has been known to treat palatal defect patients with a gold plate to which the patients missing teeth were soldered. Kingsley (1880) described artificial appliances like CPD’s for the restoration of congenital and acquired defects of the palate, nose or orbits.

9. Indications : To act as a framework over which tissues may be shaped by the surgeon To serve as a temporary prosthesis during the period of surgical correction ; To restore a patient’s cosmetic appearance rapidly for social contacts ; When surgical primary closure is not possible. When the patient’s age or local avascular condition contraindicates surgery

10. FUNCTIONS OF AN OBTURATOR Helps in feeding. It can be used to keep the wound or defective area clean. So Enhance the healing of traumatic or post surgical defects. It can help to reshape or reconstruct the palatal contour. It also improves or in some instances makes speech possible. In important area of esthetics the obturator can be used to correct lip and cheek position.

11. When deglutition and mastication are impaired, it can be used to improve functions. It reduces the flow of exudates into the mouth. The obturator can be used as a stent to hold dressing or packs post surgically. It reduces the possibility of post-operative hemorrhage.

12. TYPES OF OBTURATORS

13. 1. Obturators for Congenital Defects of Palate : A simple base plate type to correct the swallowing, feeding and speech. Obturators with a tail, consisting of a speech appliance or a speech aid prosthesis. The third type is an overlay or superimposed denture. 2. Obturators for Acquired Palatal defects: Immediate temporary/surgical obturator. Treatment/Transitional/Interim obturator. Definitive or permanent obturator.

14. CLASSIFICATION Aramany M.A (1978) has classified partially edentulous maxillectomy dental arches into six groups on the basis of the extension of the defect onto the palate, involving teeth and corresponding alveolar structure. CLASS I Resection in this group is performed along the midline of the maxilla; teeth are maintained on one side of the arch. CLASS II Defect is unilateral, retaining the anterior teeth up to canine on contra lateral side Midline Resection (JPD 2001;86:559-561)

15. CLASS III Palatal defect occurring on the central portion of the hard palate and may involve part of the soft palate. Dentition is preserved. Central resection CLASS IV Defect crosses the midline and involves both sides of the maxilla. (anterior to the first pre molar) Few teeth remain which lie in the straight line. Bilateral anterior-posterior resection

16. CLASS V Surgical defect in this case is bilateral and lies posterior to the remaining abutment teeth. Posterior resection CLASS VI It is rare to have maxillary defect anterior to the remaining abutment teeth. This occurs mostly in trauma or congenital defects rather than in planned surgical intervention. Anterior resection

17. Principles Of Obturator Design

18. CLASS I DESIGN Design can be either linear or tripodal Two or three anterior teeth are splinted whenever possible, and support is derived from the central incisor and the most posterior abutment tooth  tripodal design .

19. If the anterior teeth are not included; the linear design is recommended. Miller (1972) stated that unilateral design required bilateral retention and stabilization on the same abutment teeth. A diagonally opposed retention and stabilization can be used. Retention  buccal surface of the premolar and palatal surface of the molar. Stabilizing components  palatal surface of premolar and buccal surface of molar.

20. CLASS II DESIGN Design is tripodal Primary support  tooth nearest the defect as well as the molar on the opposite side. An indirect retainer is positioned perpendicular to the fulcrum line. Retention on all the abutment teeth is located on the buccal surface and stabilizing components are on the palatal surface .

21. CLASS III DESIGN Design is quadrilateral. Support is distributed both on premolar and molars. Retention is derived from the buccal surface and stabilization from the palatal surface.

22. CLASS IV DESIGN Design is linear. Support is located on the central of all the remaining teeth. Retention is located buccally on premolar and palatally on molar. Stabilizing components are palatal on premolars and buccal on molars.

23. CLASS V DESIGN Design is tripodal . Splinting of at least two terminal abutment teeth and I-bar clasps are placed bilaterally on the buccal surface of the most distal teeth and stabilization is located on the palatal surface. Indirect retention is located on central incisor.

24. CLASS VI DESIGN Design is quadrilateral. Two anterior teeth are splinted bilaterally and connected by a transverse splint bar.

25. Basic Objectives Of An Obturator

26. Objectives:- It should be comfortable. Should restore adequate speech, deglutition, and mastication Should be acceptable cosmetically. To achieve all these objectives, the obturator should have adequate support, retention and stability.

27. Support It gives resistance to movement of the prosthesis towards tissue.        Residual maxilla     Within the defect - Residual teeth -Alveolar ridge -Hard palate - Floor of the Orbit -Pterygoid Plate or Temporal Bone -Nasal Septum

28. Within The Defect Support It is necessary to prevent rotation of the prosthesis into the defect. a. Floor of the Orbit Use of the floor of the orbit for support should be minimal. It cannot be used for support, if orbital floor has been removed then the orbital contents will move with the movement of the prosthesis.

29. Drawbacks If prosthesis is extended up to the orbital floor it would make insertion through the oral opening difficult. (so two piece sectional prosthesis should be used) Additional weight Problems of fabrication Alteration in speech quality due to too much obturation of the resonating chamber.

30. b. Pterygoid Plate or Temporal Bone Positive contact of the prosthesis with this bony structure can be relatively extensive and adequate to support for an obturator prosthesis. c. Nasal Septum It is a poor support for extensive prosthesis because,         - It is partly cartilage         - Has little bearing area         - Is covered with nasal epithelium.

31. Support Residual palatal shelf Alveolar ridge contours Oral side of the soft palate Skin lined lateral third of the orbital floor Remaining tuberosity on the defect side The more support available the better the prognosis

32. Retention Retention is the resistance to vertical displacement of the prosthesis.        Within the residual maxilla Within the defect Residual Maxilla Retention Teeth If the defect is small and remaining teeth are stable, intra coronal retainer can be used. If the defect is large and all teeth are weak, extra coronal retainers should be used.

33. b ) Alveolar Ridge A large ridge with a broad ridge crest and flat palate is more retentive than small ridge with tapering ridge crest and high tapering palate. Within the defect retention a)  Residual soft palate Provides posterior palatal seal and prevent ingress of food. Extension of the obturator prosthesis into nasopharyngeal side of soft palate provides retention. b)  Residual Hard Palate Under cuts along the line of palatal resection into, nasal or paranasal cavity or medial wall of defect can increase retention. Obturator extension into the undercut is best provided by a soft denture base material.

34. c) Lateral Scar Band For adequate surgical closure, most maxillary resections are lined with split thickness graft along the anterior and postero – lateral walls of defects. This results in the formation of scar band which is more prominent in laterally and postero –laterally as compared to scar band anterior to premolar region. These act as good undercuts for retention. d) Height of lateral wall Engaging lateral wall of defect provides indirect retention. Longer radius undergoes less vertical displacement than shorter radius.

35. Means of providing Retention Defect side Lateral wall of the defect Undercut just superior to the skin graft mucosal junction Nasal side of the soft palate Nasal aperture Normal side Denture adhesive Osseointegrated implants The better the retention the better the prognosis.

36. STABILITY Resistance to prosthesis displacement by functional forces.  Residual Maxilla Stability Within the defect stability   Residual Maxilla Stability This is done by providing bracing components of the prosthesis frame work. Extending bracing arm inter proximally will minimize rotational as well as anterioposterior movement of the prosthesis. Within the Defect Stability Ø       Maximal extension of prosthesis in all lateral directions.

37. Stability is affected by: Alveolar ridge contours Lateral wall of the defect (if skin lined) Medial wall of the defect (if lined with palatal mucosa) Use of osseointegrated implants The better the stability the better the prognosis.

38. Prosthetic rehabilitation

39. In pre surgical phase 1. By giving feeding plates to the neonates, born with cleft lip and/or palate, to improve their nourishment and growth 2. Providing palatal obturator to the patients prior to surgery. Cleft Palate Rehabilitation

40. In post surgical phase Immediate post surgical prosthesis / obturator. Palatal obturator in un-operated cases and failures like fistula formation after surgery. Dental implants. Ear, eye, nose and other facial prostheses. Speech-aid prosthesis for better speech of cleft lip and palate patients. Replacement of teeth for better esthetics, mastication and speech

41. Instructions while managing such patient Impressions for study casts:- Impressions 2 times/year up to 2 years After that annually For Infants:- trays must be constructed ( adapt a baseplate wax against maxillary and mandibular ridges. This wax is invested and processed in acrylic. Additional trays can be made on previous casts Holes are drilled and additional retention is achieved by tray adhesive

42. Irreversible hydrocolloid material ( water 5/6 th to normal ratio and temp should be 110’ f to increase setting reaction) During maxillary impression head should be tilted at 15’ For mandibular head should be tilted slightly upward Atleast four assistant should be available:- To hold head Depress tongue and hold suction Hold the infant’s body and feet Mix impression material Loading of tray and force on tray should be proper

43. Older children and adults:- Stock tray modified with compound Early morning appoinment Empty stomach Topical anaesthetic application Tray should not be over loaded Udercuts should be blocked with gauge which is properly saturated with petrolium jelly.

44. Schmaman and carr (1992) A foam impression technique for maxillary defects This technique overcomes the problems of withdrawal of maxillectomy defect impression with or without limited space as he result of trismus. Silastic foam material is used to make an impression which expands inside the defect and is extremely elastic to escape any deformation on removal.

45. Luebke Use of sectional tray in patients with trismus. Beumer et al. In this method the impression is refined with modeling plastic,a soft flowing wax,and an elastic impression material to record the defect. Carl Use of adhesive and undercuts that add additional alginate to a set impression when necessary.

46. Prosthodontic Rehabilitation of acquired defects

47. PREOPERATIVE CONSIDERATIONS Preoperatively, the prosthodontist is concerned with four objectives; psychological support, Dental management, preoperative impression and suggestion for the surgeon. Dental Management: Teeth that would normally be considered non restorable or of no value may become extremely valuable abutment teeth for an obturator. Generally the potential risk of ostoteoradionecrosis resulting from dental treatment in the maxilla is minimum.

48. Surgical enhancements and suggestions for the surgeon : Alveolar processes and teeth as possible should be preserved without compromising complete removal of the tumor. Prognosis improves dramatically by saving teeth on surgical site because the functional fulcrum line shifts to a more favorable position.

49. In this situation the most favorable points of retention would be on the mesial of the central incisor and the distobuccal of the third molar.

50. Representation of a maxillectomy that preserves the posterior alveolar of the defect side.

51. Line of resection be made through the socket of extracted tooth. Instead of attempting to cut between roots of adjacent teeth. Interproximal cuts will result in loss of alveolar support for the tooth adjacent to the defect and can lead to the loss of the tooth post surgically. The tooth adjacent to the defect is critical as an abutment for the obturator prosthesis and its alveolar support must be maintained. If the alveolar support of the remaining tooth immediately adjacent to the defect is not adequate, it should be considered for extraction prior to the design and fabrication of the definitive obturator prosthesis.

52. Representation of the line of resection extending through the socket of an extracted first pre-molar.

53. The most effective placement of retention for this situation is to clasp the facial of the canine on the defect side and the distobuccal of the terminal molar.

54. The clinician will also plan treatment for the patient for necessary preprosthetic surgery to remove epulis , reduce pendulous tuberosities , and relieve bony undercuts. Ideally, these are performed concurrently with the tumor resection.

55. PROSTHETIC THERAPY

56. Prosthetic therapy for patients with acquired surgical defects of maxilla can be arbitrarily divided into 3 phases of treatment -Surgical obturation -Interim obturation -Definitive obturation I mmediate D elayed

57. SURGICAL OBTURATOR   It is defined as a temporary prosthesis used to restore the continuity of the hard palate immediately after surgery or traumatic loss of a portion. The obturator may be placed immediately after surgery or seven to ten days post surgically (delayed).

58. Surgical Obturation Benefits Provides a matrix upon which the surgical packing can be placed Reduces contamination of the surgical wound postoperatively. Enables relatively normal speech in the immediate postoperative period Permits deglutition postoperatively, eliminating the need for a nasogastric tube. Lessens the psychological impact of the surgery. Reduces the period of hospitalization.

59. Basic principles of design and fabrication It should be kept simple, lightweight, and inexpensive . It should be perforated in the interproximal areas so the prosthesis can be wired to residual dentition. Normal palatal contours should be reproduced. Posterior occlusion should not be established on the defect side. In edentulous patients, it should be designed like a record base, with no replacement teeth. In some instances, the existing complete or partial denture can be adapted for use as an immediate surgical obturator.

60. PROCEDURE:- I mpression must extend onto the middle third of the soft palate Tumor of hard palate extending on soft palate also

61. Teeth in the path of the resection are removed from the cast Vestibular depth on the defect side determines superior extension

62. When the wound is closed; the facial contours are nearly normal immediate surgical obturator (ISO) is placed surgical specimen is removed

63. edentulous patient the immediate surgical obturator is wired to the alveolar ridge

64. DELAYED SURGICAL OBTURATOR An alternative is to place the prosthesis 7-10 days post surgical. After initial healing and removal of the pack; the immediate obturator is usually discarded and replaced by transitional or temporary prosthesis having a definite bulbous extension and occasionally artificial anterior teeth.

65. INTERIM OBTURATION This bridges the gap between the immediate surgical obturator and the definitive prosthesis. Division between immediate and interim is not well defined. This prosthesis will be in service for approximately 2-6 months.

66. Reason for constructing interim obturator are: A definitive prosthesis is not indicated until the surgical site is healed and dimensionally stable. For some patient especially with large defects appropriate function and comfort cannot be sustained without construction of either a new prosthesis or a significant modification of immediate/delayed obturator. Addition of anterior and possibly posterior dental teeth is possible.

67. Instructions:- The tissue surface of the existing prosthesis is relined and bulb is fabricated with softliner . As the tissues contracts borders will be overextended, and the patient will have difficulty in seating the prosthesis. The patient may return , complaining that there is discomfort on the non surgical area of the maxilla or that the prosthesis is no longer retentive. Adjustments should not be made to the non surgical side of the prosthesis because the problem is likely to be tissue changes in the surgical area shifting the entire prosthesis. These contour changes are usually a combination of edema and tissue contracture. The prosthesis must be worn constantly, remove only for cleaning of the surgical site or prosthesis.

68. Interim Obturation In edentulous patients the existing denture can be relined with a temporary denture reliner and used as an interim obturator

69. The patient’s existing denture required significant modification to serve as an interim obturator The posterior extension onto the soft palate was developed with reliner. The anterior flange of the denture on the defect side needed to be shortened significantly and this area remolded with Reliner.

70. PERMANENT OR DEFINITIVE OBTURATOR: 3-4 months after surgery; consideration must be given to the construction of a definitive obturator. The timing of its construction depend on : 1. Progress of healing. 2. Prognosis for tumor control. 3.Use and timing of post surgical radiation therapy. 4. Effectiveness of the present obturator. 5. Presence or absence of teeth.

71. EDENTULOUS PATIENTS WITH MAXILLECTOMY DEFECT  Edentulous stock metal tray is selected according to the configuration of the remaining maxilla. Prior to making impression, the medial and anterior undercuts are blocked out with a gauze lubricated with petroleum jelly,

72. Irreversible hydrocolloid impression material is mixed and loaded in the tray prior to seating of the tray, impression material is placed into the posterior and lateral undercuts. Impression is made and cast is poured. The undesired undercuts recorded in the cast are blocked out with wax. Relief of one thickness base plate wax is provided for the skin graft mucosal junction and the postero lateral aspect of the defect.

73. The custom tray is fabricated in acrylic resin. Extension of the tray is verified in the mouth. Conventional border molding is advocated .

74. The tray is painted with the adhesive and elastic impression material is loaded on the tray, excess secretions are wiped from the surface of the palate, material is injected into the reasonable undercut areas and impression tray seated into position.

75. During a impression procedure (with irreversable hydrocolloid) The patient head is positioned forward then right and left laterally and finally backward and forward again. (This allow the impression material to flow into the undercut areas of hard and soft tissues.) The clinician should always be aware that manual seating pressure of the tray during border molding and impression making should be obliquely directed against the remaining alveolar ridge and not against the midpalate as is done when seating a normal maxillary denture tray. (Seating against the midpalate often causes the tray to rotate into the surgical site and away from the residual alveolar ridge without operator awareness.) The superior height of the bulb should terminate at the junction of the oral and respiratory mucosa or at the level of the nasal floor. The impression should extend about 1cm. onto the oral surface of the residual soft palate.

76. If the resection and mouth opening allow , the obturator should cover as much of the lateral wall superiorly as possible( Zarv 1967; Beumer 1979; Brown 1968). This will decrease the lever arm of the displacing force to the teeth and provide an extremely valuable area of resistance to vertical displacement.

77. Normal jaw relation procedure. VDO should only be reduced when patient exhibits severe trismus with the need to facilitate easier access for the bolus

78. Occlusal Scheme The teeth are set to contours established by the wax rim. In edentulous patient non anatomic posterior teeth are preferred and tried in patients mouth and changes are made if necessary. Lip or cheek plumper if required

79. Processing Heat cured methyl methacrylate . Obturator portion should be hollow to reduce weight If more retention is necessary  soft silicon material for the obturator segment of the prosthesis. This soft material allows the prosthesis to engage more aggressively. (But usually Silicones are avoided because of their susceptibility to deterioration in the presence of candida albicans ) Most maxillary obturators will require rebasing in the first year of delivery because of further organization of the defect with subsequent dimensional changes.

80. Denture delivery neutrocentric scheme of occlusion using no anatomic posterior denture teeth and with no vertical overlap of the anterior teeth

81. DENTULOUS PATIENT WITH MAXILLECTOMY DEFECT

82. Dentulous Patient With Maxillectomy Defect The prognosis improves with the availability of teeth to assist with the retention, support and stability of the prosthesis.

83. Impression and cast is made and surveying is done for partial frame work design. Frame work is fabricated and checked in mouth

84. Frame work is seated on the master cast, and undercuts are blocked and acrylic baseplate is constructed on the defect side. Border molding and final impression on defect side Boxing for altered cast technique Master cast

85. On the defect side only Centric contacts are preferred. Try-in patient’s mouth Bite record is taken and casts mounted on articulator

86. The processed resin is finished and polished in the usual fashion

87. occlusal contact only during centric occlusion. Delivery steps Remove Pressure points

88. Design considerations Dentulous patient with partial maxillectomy the fulcrum line is dependent on the placement of the occlusal rest. As more teeth are retained on the defect site the fulcrum line shift posteriorly. As the fulcrum line shifts posteriorly the disto lateral extension of the obturator should be lengthened as this area offers the greatest mechanical advantage. Indirect retainer should be placed anteriorly as possible from the fulcrum line.

89. Speech Evaluation Following Obturator Placement Prosthodontist can administer the lower pressure articulation test and evaluate articulation errors and inappropriate nasal resonance with the help of a speech pathologist. Weight Reduction (Hollow Obturators) Obturators should be hollow and light weight. So that teeth and supporting structures are not stressed unnecessarily.

90. ADVANTAGES OF HOLLOW BULB OBTURATO Weight is reduced so it is more comfortable and efficient . The decreases in pressure to the surrounding tissues aids in deglutition and encourages the regeneration of tissue. Does not add to the self consciousness of wearing a denture. Does not cause excessive atrophy and physiologic changes in muscle balance.

91. General Consideration regarding bulb design A bulb is not necessary :- In small to average size central palatal defect. In surgical or immediate obturator. It should be hollow to aid speech resonance, to lighten the weight. It should not be so high as to cause the eye to move during mastication. Its should be one piece, if possible. Its should not be so large as to interfere with insertion if the mouth opening is restricted.

92. TECHNIQUES Several techniques are used for fabrication of hollow bulb obturator . The commonly used ones are: 1.two piece hollow obturator 2.one piece hollow obturator

93. One piece hollow obturator : In this case shim is fabricated using three stops for proper positioning. Now lid and bulb are cured in heat cure resin as a single unit. Advantage There are no lines of the demarcation of the denture to discolour . The undercut area of the defect are thick enough to allow for the adjustment. Example:-Silicone Rubber obturator :

94. Two piece hollow obturator fabrication The cast is waxed with 2mm. thickness including all the walls of defects; Keeping open the palatal ridge side. The false palate and ridge are shaped and contoured in clay leaving an 2mm. thickness of the wax pattern. The two portions of the prosthesis are processed with heat cure resin separately. The processed obturator portion and lid portion are finished and lid is fixed over hollow bulb by cold cure resin at the margin

95. Fabrication Of One Piece Hollow Bulb Obturator ( According to Chalian and Barnett) Procedure - Try the trial denture in the mouth and make necessary modifications. - Waxup the denture after the try in. - Invest the denture in the flask in the usual manner . ( acrylic resin shim method)

96. - Boil out the wax in the conventional manner. - Block out the undercut area on defect side with plaster.

97. Construction of autopolymerizing acrylic resin shim Relieve the entire defect area with one thickness of base plate wax. Place three stops in the wax which will be deep enough to reach the underlying stone of the master cast. Place one thickness of base plate wax in the top half of the flask over the teeth and palate area to form the top wall of the shim. This will provide space for heat cure acrylic resin on the palatal side of the denture.

98. Mix the autopolymerizing acrylic resin and allow it to come to a dough consistency. Contour a layer of dough consistency acrylic resin over the wax relief to make hollow shim.

99. Close the flask and allow the resin to cure for 15 min.

100. Flush the wax from the acrylic resin shim with a steam of boiled water.

101. Trim all the excess of acrylic resin from the shim. Replace the heat cure acrylic resin shim using 3 stops for correct positioning. At this stage see that there is at least one thickness base plate wax between the shim and the cast.

102. Placement of acrylic resin shim and denture processing - Mix the heat cure acrylic resin in the usual manner. - Place a layer of acrylic resin in the bottom of the defect. - Reinsert the processed acrylic resin shim over the still soft acrylic resin mix in the defect. - Add more acrylic resin to the top half of the flask and packing is done. - Cure the resin in the usual manner. - Deflask it and trim and polish in usual manner.

103. MAXILLARY OBTURATOR WITH SILICONE-LINED HOLLOW EXTENSION (Takashi Ohyama , and Gold 1975) The hollow extension consists of two layers of different materials. The exterior of the hollow extension, which is in apposition with the defect, is coated with a soft, resilient silicone. The interior of the hollow extension is fabricated of hard self-curing acrylic resin. The resiliency of the outer surface of the hollow extension facilitates insertion of the prosthesis into deep undercuts, providing for improved retention while minimizing the tissue irritation.

104. FABRICATION Invest the wax denure -obturator in a flask, and boil out wax in the conventional manner.

105. Making the shim in self curing acrylic resin Outline the seat, cut keys for the shim in the stone of the bottom half of the flask. The seat should encircle perforated palate, measuring about 3-5mm in width and extending laterally 1-2mm. To maintain the relationship of the shim to the cast, 3 cone shaped keys should be cut within the stone of the seat of the shim. The cone shaped keys relate the shim to its proper seat.

106. Place 2 sheets of base plate wax over the mould of the defect in the flask to provide space for the silicone between shim and the defect. Fill all remaining undercuts with wax so that the shim, made from self-curing acrylic resin, can be removed. -For relief, place one thickness of baseplate wax over the teeth and palatal part of the mold on the side of the palatal defect in the top half of the flask. This wax will provide space for a thickness of heat-curing acrylic resin over the oral aspect of the prosthesis.

107. Paint a layer of thin foil substitute on the wax relief and keyed seat for the shim. Put a mixture self-curing acrylic resin into the top and bottom halves of flask on the relief wax, and spread the resin evenly to approximate one or two thickness of baseplate wax. Then, close the flask.

108. Completely flush the wax away from the cured resin shim. Drill holes with a No.3 round bur at ½ inch intervals through the lip of the shim which communicates with the space for silicone.

109. - Before packing the heat cure acrylic resin the silicone escape holes in the shim are cleaned out and closed by adding self-curing acrylic resin. -Premade shim is then pressed into position over the silicone. -Packing is done. -Place the flask in a 165 o F water bath for 9 hours. -Trim and polish the acrylic resin parts of the obturator, trim the silicone flash with scissors, a sharp blade, or abrasive finishing wheels.

110. FABRICATION OF TWO PIECE HOLLOW BULB OBTURATOR (According to Bob Palmer and Coffey in 1985). Method: Make an impression that includes the palatal defect to be obturated . Pour a stone cast, separate and prepare key at the border of the cast.

111. Apply a suitable separating media to the stone surface. Clay is sculpted to the palatal defect and missing alveolus.

112. Pour a plaster (plaster cap) over the clay, including the keys in the master cast.

113. - Remove the plaster cap when it sets, take out the clay and discard it. - Coat the tissue side of the plaster cap with a suitable separating media. - Apply thin layer of self cure acrylic resin to the defect (E) and tissue surface of the plaster cap(F). - Soft acrylic resin is added into the border of E and F and into the border of D adjacent to E. - Invert the plaster cap into the master cast. Be sure the acrylic resin is kept moist with monomer before closure. - Check the key for the proper fit and allow the acrylic resin to cure.

114. E F D

115. Remove and finish the bulb in usual manner.

116. Simplified method of making a hollow obturator (Victor Matalon in 1986) Method - Invest the impression for obturator in a flask in the normal manner - Remove the impression material. - Place separating medium on the investment surface - Roll out heat-curing acrylic resin to an approximate 2 mm thickness when it is in the doughy stage. - Pack the periphery of the obturator with rolled out heat cure acrylic resin. - Fill the center of the concavity created in the previous step with granulated sugar to within approximately 2 mm of the top.

117. Pack the mould with rolled out heat-curing resin in the usual manner. -Process the acrylic resin according to manufacturer’s specifications. - Deflask the prosthesis. -Using a No.8 bur, drill a hole in the superior surface of the obturator. -Pour out the sugar. -Use autopolymerizing acrylic resin to seal the hole made by the bur. -Finish the restoration in the customary manner.

118. MATERIALS USED FOR OBTURATOR Primitive man used stone, wood, gum, cotton to obturate the defect. Towards the end of the nineteenth century, vulcanite replaced most of the earlier materials. Gelatin glycerin compound was widely used during and after the first world war. The most common material used for the fabrication of the intra and extra oral prostheses are polymeric in nature. These includes vinyl chloride polymer and copolymers, acrylic types and silicon rubbers (heat-vulcanizing and room temperature vulcanization (RTV).

119. A) Vinyl polymers and copolymers : Vinyl chloride Vinyl acetate B) Acrylic resins : i ) Methyl methacrylate ii) Polymethyl methacrylate : C) Silicones : RTV silicones : Heat-vulcanizing silicones : D) Polyurethane Polymers : E) visible light – cured resin F) Obturating materials : Ribbon Gauze Guttapercha Silicone Rubber And Silastic Foam. Tissue Conditioners

120. Rehabilitation – Surgery vs Prosthodontics Arguments in favor of prosthodontic rehabilitation more cost effective open defect can be monitored for tumor recurrence Bulky flaps distort palatal contours and reduce the tongue space compromising speech articulation and control of the bolus during mastication. Palatal contours and speech articulation are best restored with an obturator prosthesis Mucous tends to accumulate on the nasal side of the flap causing unpleasant odors and local infections Partial denture designs and stresses on abutment teeth Inability to use the defect to facilitate retention on the side of the defect results in additional stresses on the residual dentition leading to premature loss of abutment teeth.

121. Small defects  defect was closed with local flaps.

122. Large defects are best restored prosthodontically

123. Aim . This systematic review is aimed at investigating the biomechanical stress that develops in the maxillofacial prostheses (MFP) and supporting structures and methods to optimize it . Studies - The MFP is subjected to stress, which is reflected in the form of compressive and tensile strengths. The stress is mainly concentrated the resection line and around the apices of roots of teeth next to the defect . Diversity of designs and techniques were introduced to optimize the stress distribution, such as modification of the clasp design, using materials with different mechanical properties for dentures base and retainer, use of dental (DI) and/or zygomatic implants (ZI), and free flap reconstruction before prosthetic rehabilitation .   Conclusion . Using ZI in the defective side of the dentulous maxillary defect and defective and nondefective side of the edentulous maxillary defect was found more advantageous, in terms of compression and tensile stress and retention, when compared with DI and free flap reconstruction.

124. CONCLUSION A thorough knowledge of what is normal is a must for a maxillofacial prosthodontist to understand the acquired defects which he interacts. A preplanned multidisciplinary approach is required for the success of the treatment.

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127. Thank You