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INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

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Maxillofacial prostheticsMaxillofacial prosthetics is the art and is the art and science of anatomic, functional, or science of anatomic, functional, or cosmetic reconstruction by means of non cosmetic reconstruction by means of non living substitutes of those regions in the living substitutes of those regions in the maxilla, mandible, and face that are maxilla, mandible, and face that are missing or defective because of surgical missing or defective because of surgical intervention, trauma, pathology, or intervention, trauma, pathology, or developmental or congenital malformation.developmental or congenital malformation.

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Objectives of Maxillofacial Prosthetics:

The most important The most important objectivesobjectives of maxillofacial of maxillofacial prosthetics and rehabilitation include:prosthetics and rehabilitation include:

1. 1. RRestoration of esthetics or cosmetic appearance estoration of esthetics or cosmetic appearance of the patient.of the patient.

2. 2. RRestoration of function.estoration of function.3. 3. PProtection of tissues.rotection of tissues.4. 4. TTherapeutic or healing effect.herapeutic or healing effect.5. 5. PPsychologic therapy.sychologic therapy.

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Types of Maxillofacial Deformities

CONGENITALCONGENITALCleft palateCleft palateCleft lipCleft lipFacial cleftFacial cleftMissing ear Missing ear PrognathismPrognathismACQUIREDACQUIREDAccidentsAccidentsSurgerySurgeryPathologyPathologyDEVELOPMENTALDEVELOPMENTALPrognathismPrognathismRetrognathismRetrognathism

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Probably the most common of all Probably the most common of all intraoralintraoral defects are in the defects are in the maxillamaxilla, in the form of an , in the form of an openingopening into the into the nasopharynxnasopharynx. The . The prosthesis needed to repair the defect is prosthesis needed to repair the defect is termed a termed a maxillary obturatormaxillary obturator..

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ObturatorsAnAn obturator obturator ( (LatinLatin: : obturareobturare, , to stop upto stop up) is a disc ) is a disc or plate, natural or artificial, which closes an or plate, natural or artificial, which closes an opening. opening.

A prosthesis used to close a congenital or A prosthesis used to close a congenital or acquired tissue opening, primarily of the hard acquired tissue opening, primarily of the hard palate and/or contiguous structures.-palate and/or contiguous structures.-GPT-8GPT-8

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DEFINITIVE OBTURATOR A prothesis that artificially replaces part or all of

the maxilla and associated teeth lost due to surgery or trauma.

INTERIM OBTURATOR A prosthesis that is made several weeks or

months following the surgical resection of a portion of one or both maxillae. It frequently includes replacement of teeth in the defect area.

SURGICAL OBTURATOR A temporary prosthesis used to restore the

continuity of the hard palate immediately after surgery or traumatic loss of a portion or all of the hard palate and/or contiguous alveolar structures (gingival tissue, teeth)

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The obturator fulfills many The obturator fulfills many functionsfunctions..

1.1. It can serve in lieu of a Levin tube for feeding purposes. It can serve in lieu of a Levin tube for feeding purposes.

2.2. It can be used to keep the wound or defective area cleanIt can be used to keep the wound or defective area clean

3.3. It can enhance the healing of traumatic or postsurgical It can enhance the healing of traumatic or postsurgical defects.defects.

4.4. It can help to reshape and reconstruct the palatal contour It can help to reshape and reconstruct the palatal contour and/or soft palate.and/or soft palate.

5.5. It also improves speech or, in some instances, makes It also improves speech or, in some instances, makes speech possible.speech possible.

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6.6. In the important area of esthetics, the obturator can be In the important area of esthetics, the obturator can be used to correct lip and cheek position.used to correct lip and cheek position.

7.7. It can benefit the morale of patients with maxillary It can benefit the morale of patients with maxillary defects. defects.

8.8. When deglutition and mastication are impaired, it can When deglutition and mastication are impaired, it can be used to improve function. be used to improve function.

9.9. It reduces the flow of exudates into the mouth. It reduces the flow of exudates into the mouth.

10.10. The obturator can be used a a stent to hold dressings The obturator can be used a a stent to hold dressings or packs postsurgically in maxillary resections.or packs postsurgically in maxillary resections.

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The The Aramany classificationAramany classification system of system of postsurgical maxillectomy defectspostsurgical maxillectomy defects is a is a useful tool for teaching and developing useful tool for teaching and developing obturatorobturator framework designsframework designs and and enhancing communication among enhancing communication among prosthodontists. prosthodontists.

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This article describes a series of Aramany-This article describes a series of Aramany-obturator obturator design templatesdesign templates and discusses and discusses the relevant considerations for each. In all the relevant considerations for each. In all situations, a situations, a quadrilateral or tripodal quadrilateral or tripodal designdesign is favored over a is favored over a linear designlinear design because this allows a more favorable because this allows a more favorable leverage design application that will aid in leverage design application that will aid in the the supportsupport, , stabilizationstabilization, and , and retentionretention of of the prosthesis.the prosthesis.

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IIn n 19781978 the late the late Dr.Mohammed AramanyDr.Mohammed Aramany presented the first published system of presented the first published system of classificationclassification of of postsurgical maxillary postsurgical maxillary defectsdefects. .

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He divided all defects into He divided all defects into 6 categories6 categories based on the based on the relationship of the defect to relationship of the defect to the remaining teeth and the frequency of the remaining teeth and the frequency of occurrence of the defectoccurrence of the defect..

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Dr Aramany recognized that, in addition to Dr Aramany recognized that, in addition to being communication tool, a classification being communication tool, a classification that grouped particular combinations of that grouped particular combinations of teeth and surgical defects had teeth and surgical defects had relevance relevance to the eventual design of a maxillary to the eventual design of a maxillary obturator prosthesis framework. obturator prosthesis framework.

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The classification could be used to develop The classification could be used to develop a series of basic obturator designs a series of basic obturator designs (templates) that have proven (templates) that have proven clinically clinically successfulsuccessful and and scientifically acceptable in scientifically acceptable in particular situationsparticular situations. .

These templates could then be applied to These templates could then be applied to other dental arches of similar classification other dental arches of similar classification or logically modified when slightly different or logically modified when slightly different situations presented. situations presented.

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He also recognized that although the He also recognized that although the framework designs varied greatly with framework designs varied greatly with each group, the design each group, the design objectives were objectives were always the samealways the same. .

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Design and Design and leverageleverage were to he used to were to he used to allocate, distribute, neutralize, or control allocate, distribute, neutralize, or control the anticipated functional forces so that the anticipated functional forces so that each supporting, stabilizing, or retaining each supporting, stabilizing, or retaining element of the oral cavity could be used element of the oral cavity could be used with with maximum effectivenessmaximum effectiveness without being without being stressed beyond its physiologic limits. stressed beyond its physiologic limits.

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Preservation of the remaining teethPreservation of the remaining teeth, which , which is critical for support, stabilization, and is critical for support, stabilization, and retention of the prosthesis, is a retention of the prosthesis, is a primary primary goalgoal in all classes. in all classes.

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GENERAL COMMENTS

The general principles of removable partial The general principles of removable partial denture (RPD) design apply to obturator denture (RPD) design apply to obturator prosthesis design as well. prosthesis design as well.

RelevantRelevant among these are: among these are:

(1) The need for a rigid (1) The need for a rigid major connectormajor connector

(2) (2) Guide planesGuide planes and other components that and other components that facilitate stability and bracingfacilitate stability and bracing

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(3) A design that maximizes (3) A design that maximizes supportsupport

(4) Rests that place supporting (4) Rests that place supporting forces along the forces along the long axislong axis of the abutment tooth of the abutment tooth

(5) (5) Direct retainersDirect retainers that are passive at rest and that are passive at rest and provide adequate resistance to dislodgment provide adequate resistance to dislodgment without overloading the abutment teeth without overloading the abutment teeth

(6) (6) Control of the occlusal planeControl of the occlusal plane that opposes the that opposes the defect, especially when it involves natural teeth.defect, especially when it involves natural teeth.

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In addition, In addition, many unique considerationsmany unique considerations involved involved in the design are provided by the in the design are provided by the nature of the nature of the problem and the treatment requiredproblem and the treatment required. .

Among these are:Among these are: (1) The (1) The location and sizelocation and size of the defect, especially of the defect, especially

as it relates to the remaining teethas it relates to the remaining teeth

(2) The importance of the (2) The importance of the abutment toothabutment tooth adjacent adjacent to the defect, which is critical to the support and to the defect, which is critical to the support and retention of the obturator prosthesisretention of the obturator prosthesis

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(3) The usefulness of the (3) The usefulness of the lateral scar bandlateral scar band, , which flexes to allow insertion of the which flexes to allow insertion of the prosthesis but tends to resist its prosthesis but tends to resist its displacementdisplacement

(4) The use of the (4) The use of the surveyor surveyor to examine the to examine the defect for the purpose of locating and defect for the purpose of locating and preserving useful undercuts or eliminating preserving useful undercuts or eliminating undesirable undercuts.undesirable undercuts.

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Forces that are important in designing an obturator prosthesis framework have been discussed by Aramany.

Briefly, these are:

Vertical downward forces, because of gravity

Vertical upward (occlusal) forces

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Rotational forces (which are multidirectional around constantly changing fulcrum lines)

Anteroposterior forces, because of occlusal prematurities.

The bony margin of the surgical defect often The bony margin of the surgical defect often becomes an important fulcrum when the becomes an important fulcrum when the obturator is fully seated and loaded.obturator is fully seated and loaded.

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The The prognosisprognosis of the obturator will improve with of the obturator will improve with

(1) The (1) The size size (amount remaining after surgery) and (amount remaining after surgery) and curvature of the archcurvature of the arch

(2) The (2) The qualityquality of the tissue covering the ridge and of the tissue covering the ridge and lining the defectlining the defect

(3) An (3) An abutment alignmentabutment alignment that is that is curvedcurved instead of instead of linearlinear

(4) The (4) The availability of teethavailability of teeth on the defect side for on the defect side for support and retention.support and retention.

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Many designs require full coverage of the remaining palate for maximum support.

In all in stances, the gingival margins should be relieved when they are crossed by the major connector to avoid impingement during function. The uncovering of the gingival margins in such a design should be discouraged because it is not a replacement for good oral hygiene and is probably not necessary for tissue stimulation if good hygiene is practiced.

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The class 1 category represents the The class 1 category represents the classic classic maxillary resectionmaxillary resection defect where the hard defect where the hard palate, alveolar, ridge, and dentition are palate, alveolar, ridge, and dentition are removed to the midline. This unilateral removed to the midline. This unilateral

defect is the one defect is the one most commonlymost commonly seen in seen in the maxillofacial rehabilitative practice. the maxillofacial rehabilitative practice.

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Aramany made several recommendations Aramany made several recommendations regarding the framework design for this regarding the framework design for this class, proposing a class, proposing a linear designlinear design if the if the remaining anterior teeth were notremaining anterior teeth were not to be to be used for support or retentionused for support or retention and and a tripodal a tripodal design if the anterior teeth were useddesign if the anterior teeth were used..

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Support Support is provided and shared by the

remaining natural teeth, the palate, and any structures in the defect that may be contacted for this purpose. The goal is to

ensure that the functional load is distributed as equally as possible to each of these structures via a rigid major connector.

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The natural teeth are aided in this action The natural teeth are aided in this action when the support regions of the palate and when the support regions of the palate and the defect are loaded to their maximum, the defect are loaded to their maximum, without physiologic over load. without physiologic over load.

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A A broad square or ovoid palatal formbroad square or ovoid palatal form aids aids providing a greater tissue-bearing surface to providing a greater tissue-bearing surface to resist forces (such as may be supplied by an resist forces (such as may be supplied by an occlusal load) and a greater potential for occlusal load) and a greater potential for tripodization to improve leverage.tripodization to improve leverage.

A A tapering archtapering arch is less of an aid. is less of an aid.

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Rests are placed on the most anterior abutment Rests are placed on the most anterior abutment (closest to the defect) and the mesio-occlusal (closest to the defect) and the mesio-occlusal surface of the most distal abutment tooth when surface of the most distal abutment tooth when alignment & occlusion will permit. The mesio-alignment & occlusion will permit. The mesio-occlusal posterior rest, most often located occlusal posterior rest, most often located between adjacent posterior teeth, is between adjacent posterior teeth, is accompanied by a rest on the disto-occlusal accompanied by a rest on the disto-occlusal surface of the more anterior adjacent tooth. surface of the more anterior adjacent tooth.

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This addition rest will This addition rest will prevent wedgingprevent wedging and and separation of two adjacent teeth and will separation of two adjacent teeth and will decrease the possibility of periodontal damage decrease the possibility of periodontal damage from food impaction.from food impaction.

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The completed obturator often requires a The completed obturator often requires a compound path of insertion as undercuts compound path of insertion as undercuts and support within the defect will be and support within the defect will be negotiated before the teeth are engaged. negotiated before the teeth are engaged. Guide planesGuide planes will assist in the precise will assist in the precise placement of the prosthesis once the teeth placement of the prosthesis once the teeth have been contactedhave been contacted

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They will also They will also ensureensure more predictable more predictable retention and add a greater degree of retention and add a greater degree of stability to the prosthesis. Guide planes on stability to the prosthesis. Guide planes on the anterior abutment should be kept to a the anterior abutment should be kept to a minimum vertical height (1 to 2mm) to limit minimum vertical height (1 to 2mm) to limit torque on the abutment teeth and should torque on the abutment teeth and should be physiologically adjusted. be physiologically adjusted.

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This is This is important important since movement can be expected since movement can be expected during function because of the extensive lever arm during function because of the extensive lever arm provided by the defect and the dual nature of the provided by the defect and the dual nature of the support system. This consideration becomes more support system. This consideration becomes more important as the curvature of arch decreases and the important as the curvature of arch decreases and the potential mechanical advantage of the indirect potential mechanical advantage of the indirect retainer is decreased. retainer is decreased.

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In this instant, it is especially important touse the palatal surfaces posterior teethfor additional bracing and stability

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An indirect retainer is usually located perpendicular to the fulcrum line (which connects the most anterior and most posterior rests) & as forward as possible. This is usually a canine or first premolar.

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Strategically placed indirect retainers allow Strategically placed indirect retainers allow maximum use of leverage to resist movement of the maximum use of leverage to resist movement of the prosthesis in a downward direction by the pull of prosthesis in a downward direction by the pull of gravity acting on the defect side.gravity acting on the defect side.

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RetentionRetentionRetention is supplied by direct retainer Retention is supplied by direct retainer designs that allow maximum protection of designs that allow maximum protection of the abutment teeth during functional the abutment teeth during functional movements. On the anterior abutment, a movements. On the anterior abutment, a 19- or 20-gauge wrought wire clasp of the 19- or 20-gauge wrought wire clasp of the “I-bar” design is often used to engage a “I-bar” design is often used to engage a 0.25-mm undercut on the midlabial surface 0.25-mm undercut on the midlabial surface of this abutment. of this abutment.

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Additional protection is afforded to this Additional protection is afforded to this tooth by splinting it to 1 or 2 adjacent teeth tooth by splinting it to 1 or 2 adjacent teeth with full crowns when possible or acid- with full crowns when possible or acid- etch composite resin techniques when etch composite resin techniques when crowns are not possible. crowns are not possible.

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Other possibilities include a variety of Other possibilities include a variety of cast cast clasp assembliesclasp assemblies located on the height of located on the height of contour for frictional retention only.contour for frictional retention only.

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The posterior retainer is most often a cast The posterior retainer is most often a cast circumferential clasp using 0.25 mm circumferential clasp using 0.25 mm undercut on the buccal surface. The undercut on the buccal surface. The placement of posterior clasps facing in placement of posterior clasps facing in both an anterior and posterior direction will both an anterior and posterior direction will aid in retaining both the anterior and aid in retaining both the anterior and posterior portions of the prosthesis.posterior portions of the prosthesis.

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The linear design is used for the class I The linear design is used for the class I defect when there are no anterior teeth defect when there are no anterior teeth present or when one does not desire to present or when one does not desire to use the anterior teeth. The remaining use the anterior teeth. The remaining posterior teeth are usually in a posterior teeth are usually in a relatively relatively straight line.straight line.

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SupportIn the linear design, support is provided by the remaining posterior teeth and the palatal tissues. The palate becomes more important in the linear design because the use of leverage to resist vertical dislodging forces is decreased.

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RetentionRetention

Retention is usually provided by the Retention is usually provided by the combined use of buccal premolar combined use of buccal premolar retention and lingual molar retention.retention and lingual molar retention.

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Class II includes arches in which the Class II includes arches in which the premaxilla and the premaxillarv dentition premaxilla and the premaxillarv dentition on the contralateral side is maintained. A on the contralateral side is maintained. A single, unilateral defect is located posterior single, unilateral defect is located posterior to the remaining teeth. to the remaining teeth.

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This arch is This arch is similar to a Kennedy class IIsimilar to a Kennedy class II in that a bilateral, tripodal design can in that a bilateral, tripodal design can always be used. Presurgical consultation always be used. Presurgical consultation with the surgeon is an important aspect of with the surgeon is an important aspect of care. care.

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Surgeons should be informed of the Surgeons should be informed of the improved prosthetic prognosis when a improved prosthetic prognosis when a class I situation can be converted to a class I situation can be converted to a class II situation by carefully planned class II situation by carefully planned surgery, assuming that tumor removal is surgery, assuming that tumor removal is not compromised.not compromised.

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SupportSupportSupport is similar to that in class I and is Support is similar to that in class I and is provided by rests (located on the abutment provided by rests (located on the abutment nearest to the defect and farthest from the nearest to the defect and farthest from the defect) as well as the palate. defect) as well as the palate.

Support and stability are maximized by Support and stability are maximized by generating the largest tripodal design possible generating the largest tripodal design possible and again will be aided by a and again will be aided by a square or ovoid square or ovoid palatal formpalatal form. . Double restsDouble rests are used between are used between adjacent posterior teeth.adjacent posterior teeth.

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Guide-plane locationGuide-plane location and size is similar to and size is similar to the class I situation with full use of the the class I situation with full use of the palatal surfaces of the posterior teeth.palatal surfaces of the posterior teeth.

An An indirect retainerindirect retainer located opposite the located opposite the fulcrum line and as forward as possible fulcrum line and as forward as possible usually is located on the usually is located on the canine or first canine or first premolarpremolar and completes the tripodal design. and completes the tripodal design.

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RetentionRetentionRetention is provided in a fashion similar to Retention is provided in a fashion similar to that in the class I design. The that in the class I design. The abutment abutment tooth located tooth located closest closest to the defect is to the defect is critical critical for retentionfor retention and should be engaged with a and should be engaged with a direct retainer design that resists downward direct retainer design that resists downward displacement but tends to rotate, disengage, displacement but tends to rotate, disengage, or flex when upward forces are applied. or flex when upward forces are applied.

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A cast circumferential clasp or an I-bar clasp A cast circumferential clasp or an I-bar clasp is frequently used in a 0.25 mm undercut is frequently used in a 0.25 mm undercut when the retentive terminus can be located when the retentive terminus can be located on the fulcrum line. A 19-gauge wrought wire on the fulcrum line. A 19-gauge wrought wire clasp in a 0.5 mm or less mesiofacial clasp in a 0.5 mm or less mesiofacial undercut is also a frequent choice. Additional undercut is also a frequent choice. Additional protection can be provided for this tooth by protection can be provided for this tooth by splinting it to the one or two teeth adjacent to splinting it to the one or two teeth adjacent to it.it.

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The The posterior retainerposterior retainer is most frequently a is most frequently a cast circumferential claspcast circumferential clasp using a 0.25-mm using a 0.25-mm distobuccal undercut. The placement of distobuccal undercut. The placement of posterior clasp assemblies facing in both posterior clasp assemblies facing in both an anterior and posterior direction will aid an anterior and posterior direction will aid in retaining both the anterior and posterior in retaining both the anterior and posterior portions of the prosthesis. portions of the prosthesis.

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The anterior facing clasp will also serve to The anterior facing clasp will also serve to aid any additional clasps placed opposite aid any additional clasps placed opposite the fulcrum line from the defect. The the fulcrum line from the defect. The caninecanine is frequently the location of the is frequently the location of the indirect retainer and also serves as an indirect retainer and also serves as an additional (but optional) retentive site, additional (but optional) retentive site, engaged with a 19-gauge wrought wire engaged with a 19-gauge wrought wire clasp in a 0.25-mm undercut. clasp in a 0.25-mm undercut.

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The canine is important in resisting The canine is important in resisting occlusally directed forces and will receive occlusally directed forces and will receive severe stress. If an severe stress. If an additional claspadditional clasp is is required on the canine, it should be a required on the canine, it should be a more more flexible flexible clasp in less than the normal clasp in less than the normal amount of undercut or a less flexible clasp amount of undercut or a less flexible clasp on the height of contour so that on the height of contour so that frictional frictional retention will be supplied.retention will be supplied.

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A combination of buccal and palatal retention isA combination of buccal and palatal retention isalmost never indicated for this classification foralmost never indicated for this classification forseveral reasons.several reasons. Among these are :Among these are :

(1)(1) Additional bracingAdditional bracing and and cross-arch stabilizationcross-arch stabilization will will be be lostlost when lingual retention is engaged. when lingual retention is engaged.

(2) (2) Increased rotation will be notedIncreased rotation will be noted with an actual with an actual decrease in retention because to the short length decrease in retention because to the short length and shallow gingivally located curvature of the and shallow gingivally located curvature of the palatal surfaces of the molar teeth and palatal surfaces of the molar teeth and disengagement of the lingual undercut on slight disengagement of the lingual undercut on slight displacement; and displacement; and

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3) The location of lingual retentive clasps often results in a major connector that has multiplesmall regions that trap food or irritate thetongue.

Occlusion on the defect side is important because the occlusally directed forces can be destructive. Occlusal schemes with fewer, smaller teeth, located further toward the anterior and devoid of premature or deflective contacts is desirable.

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Class III involves a midline defect of the hard Class III involves a midline defect of the hard palate and may include a variable portion of palate and may include a variable portion of the soft palate as well. The dentition is usually the soft palate as well. The dentition is usually preserved, making this obturator prosthesis preserved, making this obturator prosthesis design simple and effective. The classification design simple and effective. The classification and design closely resemble the and design closely resemble the Kennedy Kennedy class III RPD design.class III RPD design.

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SupportSupport

Support is supplied by the remaining Support is supplied by the remaining natural teethnatural teeth via via widely separated and widely separated and bilaterally located restsbilaterally located rests. The canines and . The canines and molars are usually selected to generate molars are usually selected to generate the largest quadrilateral shape possible the largest quadrilateral shape possible while avoiding alignment and occlusion while avoiding alignment and occlusion and hygiene problems, and providing good and hygiene problems, and providing good esthetics. esthetics.

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Little or no support is expected from the Little or no support is expected from the palate or the defect. Bilateral symmetry of palate or the defect. Bilateral symmetry of the major connector design and avoidance of the major connector design and avoidance of the rugae area is desirable when possible.the rugae area is desirable when possible.

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Guide planes are usually Guide planes are usually shortshort because they because they are located on the palatal surfaces of the are located on the palatal surfaces of the posterior teeth. The proximal surfaces may posterior teeth. The proximal surfaces may be liberally used if edentulous spaces are be liberally used if edentulous spaces are present. Very little movement of the present. Very little movement of the prosthesis should occur in function; prosthesis should occur in function; therefore, these guide planes may be long therefore, these guide planes may be long and physiologic adjustment should not be and physiologic adjustment should not be necessary.necessary.

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Indirect retentionIndirect retention is not required because is not required because each terminus is supported by a each terminus is supported by a direct direct retainerretainer; therefore, rotation around a ; therefore, rotation around a common fulcrum should not occur.common fulcrum should not occur.

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RetentionRetentionRetention is often provided with Retention is often provided with cast cast retainersretainers using using 0.25-mm undercuts0.25-mm undercuts on the on the facial surfaces of the teeth. These may be facial surfaces of the teeth. These may be circumferential retainerscircumferential retainers, , I-barsI-bars, or , or modified modified T-barsT-bars, depending on the location of the , depending on the location of the retentive sites, the esthetic requirements, retentive sites, the esthetic requirements, and the presence of tissue undercuts. and the presence of tissue undercuts.

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Combination-type retainers can be used to Combination-type retainers can be used to an esthetic advantage because they can an esthetic advantage because they can engage a deeper undercutengage a deeper undercut (0.5 mm) and (0.5 mm) and may thus be placed in a may thus be placed in a less conspicuous less conspicuous regionregion..

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Aramany class IV obturator is a linear design because of presence of only posterior Aramany class IV obturator is a linear design because of presence of only posterior teeth in a straight line. Retention is problematic. Combination of buccal and lingual teeth in a straight line. Retention is problematic. Combination of buccal and lingual retention may be necessary if useful retention cannot be found within defect.retention may be necessary if useful retention cannot be found within defect.

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Class IV situations Class IV situations involveinvolve the surgical the surgical removal of the entire premaxillae, leaving removal of the entire premaxillae, leaving a a bilateral defect anteriorlybilateral defect anteriorly and and a lateral a lateral defect posteriorlydefect posteriorly. There are often a few . There are often a few remaining posterior teeth located in a remaining posterior teeth located in a relatively straight line, creating a unilateral relatively straight line, creating a unilateral linear design problem where leverage linear design problem where leverage cannot be used to an effective degree.cannot be used to an effective degree.

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SupportSupport

Support is usually provided by Support is usually provided by restsrests located located centrally on all of the remaining teeth. centrally on all of the remaining teeth. Channel rests or multiple mesio-occlusal and Channel rests or multiple mesio-occlusal and disto-occlusal results are often designed. disto-occlusal results are often designed. The The defectdefect should also be engaged to use, should also be engaged to use, as much as possible, any sites within the as much as possible, any sites within the defect that may be contacted. defect that may be contacted.

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These are the midline of the palatal incision, These are the midline of the palatal incision, when palatal mucosa has been preserved to when palatal mucosa has been preserved to cover this region, the floor of the orbit, the cover this region, the floor of the orbit, the bony pterygoid plates, and the anterior surface bony pterygoid plates, and the anterior surface of the temporal bone. If these regions are of the temporal bone. If these regions are covered by respiratory mucosa from the nasal covered by respiratory mucosa from the nasal cavity, little added support can be achieved.cavity, little added support can be achieved.

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RetentionRetention

Retention in this classification is Retention in this classification is problematicproblematic. Often a mixture of . Often a mixture of buccal buccal retentionretention on the premolars and on the premolars and palatal palatal retentionretention on the molars is used in a fashion on the molars is used in a fashion similar to the class I linear design. similar to the class I linear design.

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This leads often to the same problems This leads often to the same problems discussed in discussed in class IIclass II situations when a situations when a combination of buccal and palatal combination of buccal and palatal retention is used: retention is used: loss of bracing arid loss of bracing arid stabilizationstabilization, , increased rotationincreased rotation, and , and the the creation of small irritating spacescreation of small irritating spaces in the in the major connector design.major connector design.

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Retentive sites should be located on the Retentive sites should be located on the facial surfaces of the remaining teeth and facial surfaces of the remaining teeth and the lateral wall of the surgical defect via the lateral wall of the surgical defect via the the superiolateral extensionsuperiolateral extension of the of the obturator section in the engagement of the obturator section in the engagement of the lateral scar band. lateral scar band. Reduced posterior Reduced posterior occlusionocclusion (size and number of teeth) is (size and number of teeth) is also a useful suggestion. also a useful suggestion.

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If no If no lateral scar bandlateral scar band exists, because a exists, because a split-thickness skin graft was not placed or split-thickness skin graft was not placed or because one could not be maintained, the because one could not be maintained, the prosthodontist may have prosthodontist may have no choiceno choice but to but to use a combination of buccal and palatal use a combination of buccal and palatal retention.retention.

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This situation involves a This situation involves a bilateral posterior bilateral posterior surgical defectsurgical defect located posterior to the located posterior to the remaining teeth. Many or all of the teeth remaining teeth. Many or all of the teeth are present anterior to the defect. Labial are present anterior to the defect. Labial stabilization and the use of splinting, stabilization and the use of splinting, especially of the terminal abutments, is especially of the terminal abutments, is desirable.desirable.

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SupportSupport

Support is provided by rests located on the Support is provided by rests located on the mesio-occlusalmesio-occlusal surface of the most posterior surface of the most posterior abutment. These rests define the abutment. These rests define the fulcrum linefulcrum line around which most of the expected movement around which most of the expected movement will occur. If adjacent teeth are involved, double will occur. If adjacent teeth are involved, double rests are used for reasons outlined earlier. rests are used for reasons outlined earlier. StabilizationStabilization and and bracingbracing is provided by broad is provided by broad palatal coverage and contact with the palatal palatal coverage and contact with the palatal surfaces of the remaining teeth.surfaces of the remaining teeth.

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Indirect retention is provided by rests Indirect retention is provided by rests located as far forward of the located as far forward of the fulcrum fulcrum lineline as possible. This usually places as possible. This usually places them on the them on the central incisorscentral incisors, which , which often presents an occlusal problem often presents an occlusal problem that may require that may require minor occlusal minor occlusal equilibrationequilibration. .

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The location of the indirect retainer essentially converts the design to an efficient large tripod that uses leverage to resist downward displacement of the prosthesis. Positive rest seats are a critical necessity to eliminate the strong labial force generated by the downward movement of the prosthesis.

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RetentionRetentionThe I-bar retainer is ideally suited for this The I-bar retainer is ideally suited for this situation. Located in a situation. Located in a 0.25-mm 0.25-mm midbuccal midbuccal undercut very close to the undercut very close to the fulcrum linefulcrum line, it , it provides for resistance to dislodgment and provides for resistance to dislodgment and rotates in function. When the remaining soft rotates in function. When the remaining soft palate is scarred and relatively immobile it can palate is scarred and relatively immobile it can also be used to provide added retention fur the also be used to provide added retention fur the posterior portion of the prosthesis.posterior portion of the prosthesis.

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A swing-lock type of prosthesis is a design A swing-lock type of prosthesis is a design possibility in this situation, especially if the possibility in this situation, especially if the patient can tolerate splinting of all of the patient can tolerate splinting of all of the remaining teeth.remaining teeth.

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The class VI defect is a The class VI defect is a rare surgical rare surgical creationcreation. Most of ten it results from a . Most of ten it results from a congenital anomaly or trauma such as an congenital anomaly or trauma such as an automobile accidentautomobile accident or a or a self-inflicted woundself-inflicted wound that removes the entire premaxillae (and may that removes the entire premaxillae (and may include a portion of one or both of the include a portion of one or both of the maxillae), leaving a single bilateral defect maxillae), leaving a single bilateral defect located anterior to the remaining teeth. located anterior to the remaining teeth.

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Surgical defectsSurgical defects of this nature are usually of this nature are usually smallsmall. . Nonsurgical Nonsurgical defects are usually defects are usually largelarge and difficult to manage. and difficult to manage.

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SupportSupport

Support is provided by rests located on the Support is provided by rests located on the disto occlusal surfaces of the most anterior disto occlusal surfaces of the most anterior abutment teeth. Double rests are used abutment teeth. Double rests are used when adjacent posterior teeth are involved. when adjacent posterior teeth are involved. Greater stability is provided by placing Greater stability is provided by placing additional rests as far posteriorly as additional rests as far posteriorly as possible. possible.

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The most posterior rests, similar to the The most posterior rests, similar to the Kennedy class IV situation, may be Kennedy class IV situation, may be considered indirect retainers, resisting the considered indirect retainers, resisting the vertical downward displacement of the vertical downward displacement of the anterior segment of the prosthesis. In anterior segment of the prosthesis. In extremely large class VI situations, indirect extremely large class VI situations, indirect retention may not be possible.retention may not be possible.

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The remaining natural teeth provide all of the The remaining natural teeth provide all of the support, with little support derived from the defect.support, with little support derived from the defect.

Guide planes are usually located on the Guide planes are usually located on the proximal stir- faces adjacent to the defect and proximal stir- faces adjacent to the defect and should be kept to minimal length should be kept to minimal length (1 to 2 mm)(1 to 2 mm) to to avoid avoid traumatrauma to the abutment teeth during to the abutment teeth during expected movements of the prosthesis.expected movements of the prosthesis.

Splinting with a cross-arch tissue bar is also Splinting with a cross-arch tissue bar is also a possibility.a possibility.

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RetentionRetentionRetention is most often provided simply Retention is most often provided simply with cast retainers using with cast retainers using 0.25 mm0.25 mm of facial of facial undercut. The I-bar located on the anterior undercut. The I-bar located on the anterior abutment in a midfacial undercut close to abutment in a midfacial undercut close to the fulcrum line can function effectively. the fulcrum line can function effectively.

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Combination retainers may also be used Combination retainers may also be used on the anterior abutments for on the anterior abutments for esthetic esthetic reasons or when protection of the anterior reasons or when protection of the anterior abutments is a consideration.abutments is a consideration.

Effective accessory retention can also Effective accessory retention can also be achieved by extending the prosthesis be achieved by extending the prosthesis anteriorly into the anteriorly into the nasal aperturenasal aperture. Cosmetic . Cosmetic support of the nose and upper lip is also support of the nose and upper lip is also possible when adequate retention is present.possible when adequate retention is present.

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SUMMARY AND CONCLUSIONSUMMARY AND CONCLUSION

The Aramany classification system The Aramany classification system of postsurgical maxillary defects is a useful tool of postsurgical maxillary defects is a useful tool for teaching and developing framework designs for teaching and developing framework designs for obturator prostheses and for enhancing for obturator prostheses and for enhancing communication among prosthodontists.communication among prosthodontists.

A series of obturator prosthesis design A series of obturator prosthesis design templates and the relevant considerations for templates and the relevant considerations for each has been discussed. each has been discussed.

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In all situations, a In all situations, a quadrilateral quadrilateral or or tripodaltripodal design is favored over a linear design is favored over a linear design because this allows a more design because this allows a more favorable application of leverage design favorable application of leverage design for the support, stabilization, and retention for the support, stabilization, and retention of the prosthesis.of the prosthesis.

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The templates provided should he The templates provided should he considered basic types that can be applied considered basic types that can be applied in similar situations or logically modified by in similar situations or logically modified by using the design principles presented using the design principles presented when the situation warrants. when the situation warrants.

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Some of these situations may be medical Some of these situations may be medical necessity, the presence of modification necessity, the presence of modification spaces, periodontal considerations, spaces, periodontal considerations, opposing occlusion, location of hard or soft opposing occlusion, location of hard or soft tissue undercuts, contingency planning, or tissue undercuts, contingency planning, or the desire to simplify the design.the desire to simplify the design.

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Although some dentists may disagree with Although some dentists may disagree with the various facets of the templates the various facets of the templates presented, there is value for the student, presented, there is value for the student, teacher, or practitioner in the development teacher, or practitioner in the development of a systematic analysis of the design of of a systematic analysis of the design of maxillary obturator prostheses.maxillary obturator prostheses.

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REFERENCESREFERENCES1.1. Aramany MA. Basic principles of obturator Aramany MA. Basic principles of obturator

design for partially edentulous patients. Part I: design for partially edentulous patients. Part I: classification. J Prosthet Dent 1978;40: 554-7.classification. J Prosthet Dent 1978;40: 554-7.

2. 2. Rahn AO, Goldman BC, Parr CR. Rahn AO, Goldman BC, Parr CR. Prosthodontic principles in the surgical Prosthodontic principles in the surgical planning for maxillary and mandibular planning for maxillary and mandibular resection patients. J Prosthet Dent resection patients. J Prosthet Dent 1979;42:429-33.1979;42:429-33.

3.3. Brown KE. Peripheral considerations in Brown KE. Peripheral considerations in improving obturator retention. J Prosthet Dent improving obturator retention. J Prosthet Dent 1968;20: 176-80.1968;20: 176-80.

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4. Beumer J, Curtis TA, .Firtell DN. maxillofacial 4. Beumer J, Curtis TA, .Firtell DN. maxillofacial rehabilitation. St. Louis Mosby; 1979. p. 188-243.rehabilitation. St. Louis Mosby; 1979. p. 188-243.

5, Aramanv MA. Basic principles of obturator design 5, Aramanv MA. Basic principles of obturator design for partially edentulous patients. Part II: design for partially edentulous patients. Part II: design principles. J Prosthet Dent 1978;40:656-62.principles. J Prosthet Dent 1978;40:656-62.

6. Firtell DN, Grisius RI. Retention of obturator 6. Firtell DN, Grisius RI. Retention of obturator removable partial dentures: a comparison of removable partial dentures: a comparison of buccal and lingual retention. J Prosthet Dent buccal and lingual retention. J Prosthet Dent 1980;43:212-7.1980;43:212-7.

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7. Desjardins RP. Obturator prosthesis design for 7. Desjardins RP. Obturator prosthesis design for acquired maxillary defects. acquired maxillary defects. J Prosthet Dent J Prosthet Dent 1978;39:424-32.1978;39:424-32.

8. Fiebiger GE, Rahn AO, Lundquist DO, Moise 8. Fiebiger GE, Rahn AO, Lundquist DO, Moise PK. PK. Movement abutments by removable partial Movement abutments by removable partial denture frameworks with a hemimaxillectomy denture frameworks with a hemimaxillectomy obturator. J Prosthet Dent 1975,34:555-60.obturator. J Prosthet Dent 1975,34:555-60.

9. Stewart KL, Rudd KD, Kuebker WA. Clinical 9. Stewart KL, Rudd KD, Kuebker WA. Clinical removable partial prosthodontics. St. Louis: removable partial prosthodontics. St. Louis: Mosby; 1983. p. 663.Mosby; 1983. p. 663.

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