Maxillofacial Prosthetics Classification and Design

Maxillofacial prostheticsMaxillofacial prosthetics is the art andis the art and
science of anatomic, functional, orscience of anatomic, functional, or
cosmetic reconstruction by means of noncosmetic reconstruction by means of non
living substitutes of those regions in theliving substitutes of those regions in the
maxilla, mandible, and face that aremaxilla, mandible, and face that are
missing or defective because of surgicalmissing or defective because of surgical
intervention, trauma, pathology, orintervention, trauma, pathology, or
developmental or congenital malformation.developmental or congenital malformation.
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

Objectives of Maxillofacial Prosthetics:
The most importantThe most important objectivesobjectives of maxillofacialof maxillofacial
prosthetics and rehabilitation include:prosthetics and rehabilitation include:
1.1. RRestoration of esthetics or cosmetic appearanceestoration 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.

Types of Maxillofacial Deformities
CONGENITALCONGENITAL
Cleft palateCleft palate
Cleft lipCleft lip
Facial cleftFacial cleft
Missing earMissing ear
PrognathismPrognathism
ACQUIREDACQUIRED
AccidentsAccidents
SurgerySurgery
PathologyPathology
DEVELOPMENTALDEVELOPMENTAL
PrognathismPrognathism
RetrognathismRetrognathism

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

Obturators
AnAn obturatorobturator ((LatinLatin:: obturareobturare,, to stop upto stop up) is a disc) is a disc
or plate, natural or artificial, which closes anor plate, natural or artificial, which closes an
opening.opening.
A prosthesis used to close a congenital orA prosthesis used to close a congenital or
acquired tissue opening, primarily of the hardacquired tissue opening, primarily of the hard
palate and/or contiguous structures.-palate and/or contiguous structures.-GPT-8GPT-8

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)

The obturator fulfills manyThe 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 postsurgicalIt can enhance the healing of traumatic or postsurgical
defects.defects.
4.4. It can help to reshape and reconstruct the palatal contourIt 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, makesIt also improves speech or, in some instances, makes
speech possible.speech possible.

6.6. In the important area of esthetics, the obturator can beIn 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 maxillaryIt can benefit the morale of patients with maxillary
defects.defects.
8.8. When deglutition and mastication are impaired, it canWhen 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 dressingsThe obturator can be used a a stent to hold dressings
or packs postsurgically in maxillary resections.or packs postsurgically in maxillary resections.

TheThe Aramany classificationAramany classification system ofsystem of
postsurgical maxillectomy defectspostsurgical maxillectomy defects is ais a
useful tool for teaching and developinguseful tool for teaching and developing
obturatorobturator framework designsframework designs andand
enhancing communication amongenhancing communication among
prosthodontists.prosthodontists.

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

IInn 19781978 the latethe late Dr.Mohammed AramanyDr.Mohammed Aramany
presented the first published system ofpresented the first published system of
classificationclassification ofof postsurgical maxillarypostsurgical maxillary
defectsdefects..

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

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

The classification could be used to developThe classification could be used to develop
a series of basic obturator designsa series of basic obturator designs
(templates) that have proven(templates) that have proven clinicallyclinically
successfulsuccessful andand scientifically acceptable inscientifically acceptable in
particular situationsparticular situations..
These templates could then be applied toThese templates could then be applied to
other dental arches of similar classificationother dental arches of similar classification
or logically modified when slightly differentor logically modified when slightly different
situations presented.situations presented.

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

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

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

GENERAL COMMENTS
The general principles of removable partialThe general principles of removable partial
denture (RPD) design apply to obturatordenture (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 thatand other components that
facilitate stability and bracingfacilitate stability and bracing

(3) A design that maximizes(3) A design that maximizes supportsupport
(4) Rests that place supporting(4) Rests that place supporting forces along theforces along the
long axislong axis of the abutment toothof the abutment tooth
(5)(5) Direct retainersDirect retainers that are passive at rest andthat are passive at rest and
provide adequate resistance to dislodgmentprovide adequate resistance to dislodgment
without overloading the abutment teethwithout overloading the abutment teeth
(6)(6) Control of the occlusal planeControl of the occlusal plane that opposes thethat opposes the
defect, especially when it involves natural teeth.defect, especially when it involves natural teeth.

In addition,In addition, many unique considerationsmany unique considerations involvedinvolved
in the design are provided by thein the design are provided by the nature of thenature 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, especiallyof 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 adjacentadjacent
to the defect, which is critical to the support andto the defect, which is critical to the support and
retention of the obturator prosthesisretention of the obturator prosthesis

(3) The usefulness of the(3) The usefulness of the lateral scar bandlateral scar band,,
which flexes to allow insertion of thewhich flexes to allow insertion of the
prosthesis but tends to resist itsprosthesis but tends to resist its
displacementdisplacement
(4) The use of the(4) The use of the surveyorsurveyor to examine theto examine the
defect for the purpose of locating anddefect for the purpose of locating and
preserving useful undercuts or eliminatingpreserving useful undercuts or eliminating
undesirable undercuts.undesirable undercuts.

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

Rotational forces (which are multidirectional
around constantly changing fulcrum lines)
Anteroposterior forces, because of occlusal
prematurities.
The bony margin of the surgical defect oftenThe bony margin of the surgical defect often
becomes an important fulcrum when thebecomes an important fulcrum when the
obturator is fully seated and loaded.obturator is fully seated and loaded.

TheThe prognosisprognosis of the obturator will improve withof the obturator will improve with
(1) The(1) The sizesize (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 andof the tissue covering the ridge and
lining the defectlining the defect
(3) An(3) An abutment alignmentabutment alignment that isthat is curvedcurved instead ofinstead of
linearlinear
(4) The(4) The availability of teethavailability of teeth on the defect side foron the defect side for
support and retention.support and retention.

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.

The class 1 category represents theThe class 1 category represents the classicclassic
maxillary resectionmaxillary resection defect where the harddefect where the hard
palate, alveolar, ridge, and dentition arepalate, alveolar, ridge, and dentition are
removed to the midline. This unilateralremoved to the midline. This unilateral
defect is the onedefect is the one most commonlymost commonly seen inseen in
the maxillofacial rehabilitative practice.the maxillofacial rehabilitative practice.

Aramany made several recommendationsAramany made several recommendations
regarding the framework design for thisregarding the framework design for this
class, proposing aclass, proposing a linear designlinear design if theif the
remaining anterior teeth were notremaining anterior teeth were not to beto be
used for support or retentionused for support or retention andand aa
tripodal design if the anterior teeth weretripodal design if the anterior teeth were
usedused..

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.

The natural teeth are aided in this actionThe natural teeth are aided in this action
when the support regions of the palate andwhen 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.

AA broad square or ovoid palatal formbroad square or ovoid palatal form aidsaids
providing a greater tissue-bearing surface toproviding a greater tissue-bearing surface to
resist forces (such as may be supplied by anresist forces (such as may be supplied by an
occlusal load) and a greater potential forocclusal load) and a greater potential for
tripodization to improve leverage.tripodization to improve leverage.
AA tapering archtapering arch is less of an aid.is less of an aid.

Rests are placed on the most anterior abutmentRests 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 whensurface of the most distal abutment tooth when
alignment & occlusion will permit. The mesio-alignment & occlusion will permit. The mesio-
occlusal posterior rest, most often locatedocclusal posterior rest, most often located
between adjacent posterior teeth, isbetween adjacent posterior teeth, is
accompanied by a rest on the disto-occlusalaccompanied by a rest on the disto-occlusal
surface of the more anterior adjacent tooth.surface of the more anterior adjacent tooth.

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

The completed obturator often requires aThe completed obturator often requires a
compound path of insertion as undercutscompound path of insertion as undercuts
and support within the defect will beand 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 precisewill assist in the precise
placement of the prosthesis once the teethplacement of the prosthesis once the teeth
have been contactedhave been contacted

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

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

In this instant, it is especially important to
use the palatal surfaces posterior teeth
for additional bracing and stability

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.

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

RetentionRetention
Retention is supplied by direct retainerRetention is supplied by direct retainer
designs that allow maximum protection ofdesigns that allow maximum protection of
the abutment teeth during functionalthe abutment teeth during functional
movements. On the anterior abutment, amovements. On the anterior abutment, a
19- or 20-gauge wrought wire clasp of the19- 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 surface0.25-mm undercut on the midlabial surface
of this abutment.of this abutment.

Additional protection is afforded to thisAdditional protection is afforded to this
tooth by splinting it to 1 or 2 adjacent teethtooth 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 whenetch composite resin techniques when
crowns are not possible.crowns are not possible.

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

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

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

Support
In 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.

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

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

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

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

SupportSupport
Support is similar to that in class I and isSupport is similar to that in class I and is
provided by rests (located on the abutmentprovided by rests (located on the abutment
nearest to the defect and farthest from thenearest to the defect and farthest from the
defect) as well as the palate.defect) as well as the palate.
Support and stability are maximized bySupport and stability are maximized by
generating the largest tripodal design possiblegenerating the largest tripodal design possible
and again will be aided by aand again will be aided by a square or ovoidsquare or ovoid
palatal formpalatal form.. Double restsDouble rests are used betweenare used between
adjacent posterior teeth.adjacent posterior teeth.

Guide-plane locationGuide-plane location and size is similar toand size is similar to
the class I situation with full use of thethe class I situation with full use of the
palatal surfaces of the posterior teeth.palatal surfaces of the posterior teeth.
AnAn indirect retainerindirect retainer located opposite thelocated opposite the
fulcrum line and as forward as possiblefulcrum line and as forward as possible
usually is located on theusually is located on the canine or firstcanine or first
premolarpremolar and completes the tripodal design.and completes the tripodal design.

RetentionRetention
Retention is provided in a fashion similar toRetention is provided in a fashion similar to
that in the class I design. Thethat in the class I design. The abutmentabutment
tooth locatedtooth located closestclosest to the defect isto the defect is criticalcritical
for retentionfor retention and should be engaged with aand should be engaged with a
direct retainer design that resists downwarddirect 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.

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

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

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

The canine is important in resistingThe canine is important in resisting
occlusally directed forces and will receiveocclusally directed forces and will receive
severe stress. If ansevere stress. If an additional claspadditional clasp isis
required on the canine, it should be arequired on the canine, it should be a
moremore flexibleflexible clasp in less than the normalclasp in less than the normal
amount of undercut or a less flexible claspamount of undercut or a less flexible clasp
on the height of contour so thaton the height of contour so that frictionalfrictional
retention will be supplied.retention will be supplied.

A combination of buccal and palatal retention isA combination of buccal and palatal retention is
almost never indicated for this classification foralmost never indicated for this classification for
several reasons.several reasons.
Among these are :Among these are :
(1)(1) Additional bracingAdditional bracing andand cross-arch stabilizationcross-arch stabilization willwill
bebe lostlost when lingual retention is engaged.when lingual retention is engaged.
(2)(2) Increased rotation will be notedIncreased rotation will be noted with an actualwith an actual
decrease in retention because to the short lengthdecrease in retention because to the short length
and shallow gingivally located curvature of theand shallow gingivally located curvature of the
palatal surfaces of the molar teeth andpalatal surfaces of the molar teeth and
disengagement of the lingual undercut on slightdisengagement of the lingual undercut on slight
displacement; anddisplacement; and

3) The location of lingual retentive clasps often
results in a major connector that has multiple
small regions that trap food or irritate the
tongue.
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.

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

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

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

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

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

RetentionRetention
Retention is often provided withRetention is often provided with castcast
retainersretainers usingusing 0.25-mm undercuts0.25-mm undercuts on theon the
facial surfaces of the teeth. These may befacial surfaces of the teeth. These may be
circumferential retainerscircumferential retainers,, I-barsI-bars, or, or
modified T-barsmodified T-bars, depending on the location, depending on the location
of the retentive sites, the estheticof the retentive sites, the esthetic
requirements, and the presence of tissuerequirements, and the presence of tissue
undercuts.undercuts.

Combination-type retainers can be used toCombination-type retainers can be used to
an esthetic advantage because they canan 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 amay thus be placed in a less conspicuousless conspicuous
regionregion..

Aramany class IV obturator is a linear design because of presence of only posteriorAramany 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 lingualteeth 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.

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

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

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

RetentionRetention
Retention in this classification isRetention in this classification is
problematicproblematic. Often a mixture of. Often a mixture of buccalbuccal
retentionretention on the premolars andon the premolars and palatalpalatal
retentionretention on the molars is used in a fashionon the molars is used in a fashion
similar to the class I linear design.similar to the class I linear design.

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

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

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

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

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

Indirect retention is provided by restsIndirect retention is provided by rests
located as far forward of thelocated as far forward of the fulcrumfulcrum
lineline as possible. This usually placesas possible. This usually places
them on thethem on the central incisorscentral incisors, which, which
often presents an occlusal problemoften presents an occlusal problem
that may requirethat may require minor occlusalminor occlusal
equilibrationequilibration..

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.

RetentionRetention
The I-bar retainer is ideally suited for thisThe I-bar retainer is ideally suited for this
situation. Located in asituation. Located in a 0.25-mm0.25-mm midbuccalmidbuccal
undercut very close to theundercut very close to the fulcrum linefulcrum line, it, it
provides for resistance to dislodgment andprovides for resistance to dislodgment and
rotates in function. When the remaining softrotates in function. When the remaining soft
palate is scarred and relatively immobile it canpalate is scarred and relatively immobile it can
also be used to provide added retention fur thealso be used to provide added retention fur the
posterior portion of the prosthesis.posterior portion of the prosthesis.

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

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

Surgical defectsSurgical defects of this nature are usuallyof this nature are usually
smallsmall.. NonsurgicalNonsurgical defects are usuallydefects are usually
largelarge and difficult to manage.and difficult to manage.

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

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

The remaining natural teeth provide all of theThe 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 theGuide planes are usually located on the
proximal stir- faces adjacent to the defect andproximal stir- faces adjacent to the defect and
should be kept to minimal lengthshould be kept to minimal length (1 to 2 mm)(1 to 2 mm) toto
avoidavoid traumatrauma to the abutment teeth duringto the abutment teeth during
expected movements of the prosthesis.expected movements of the prosthesis.
Splinting with a cross-arch tissue bar is also aSplinting with a cross-arch tissue bar is also a
possibility.possibility.

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

Combination retainers may also be usedCombination retainers may also be used
on the anterior abutments foron the anterior abutments for estheticesthetic
reasons or when protection of the anteriorreasons or when protection of the anterior
abutments is a consideration.abutments is a consideration.
Effective accessory retention can also beEffective accessory retention can also be
achieved by extending the prosthesisachieved by extending the prosthesis
anteriorly into theanteriorly into the nasal aperturenasal aperture. Cosmetic. Cosmetic
support of the nose and upper lip is alsosupport of the nose and upper lip is also
possible when adequate retention is present.possible when adequate retention is present.

SUMMARY AND CONCLUSIONSUMMARY AND CONCLUSION
The Aramany classification system ofThe Aramany classification system of
postsurgical maxillary defects is a useful tool forpostsurgical maxillary defects is a useful tool for
teaching and developing framework designs forteaching and developing framework designs for
obturator prostheses and for enhancingobturator prostheses and for enhancing
communication among prosthodontists.communication among prosthodontists.
A series of obturator prosthesis designA series of obturator prosthesis design
templates and the relevant considerations fortemplates and the relevant considerations for
each has been discussed.each has been discussed.

In all situations, aIn all situations, a quadrilateralquadrilateral oror
tripodaltripodal design is favored over a lineardesign is favored over a linear
design because this allows a moredesign because this allows a more
favorable application of leverage designfavorable application of leverage design
for the support, stabilization, and retentionfor the support, stabilization, and retention
of the prosthesis.of the prosthesis.

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

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

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

REFERENCESREFERENCES
1.1. Aramany MA. Basic principles of obturatorAramany 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 surgicalProsthodontic principles in the surgical
planning for maxillary and mandibularplanning for maxillary and mandibular
resection patients. J Prosthet Dentresection patients. J Prosthet Dent
1979;42:429-33.1979;42:429-33.
3.3. Brown KE. Peripheral considerations inBrown KE. Peripheral considerations in
improving obturator retention. J Prosthet Dentimproving obturator retention. J Prosthet Dent
1968;20: 176-80.1968;20: 176-80.

4. Beumer J, Curtis TA, .Firtell DN. maxillofacial4. 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 design5, Aramanv MA. Basic principles of obturator design
for partially edentulous patients. Part II: designfor 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 obturator6. Firtell DN, Grisius RI. Retention of obturator
removable partial dentures: a comparison ofremovable partial dentures: a comparison of
buccal and lingual retention. J Prosthet Dentbuccal and lingual retention. J Prosthet Dent
1980;43:212-7.1980;43:212-7.

7. Desjardins RP. Obturator prosthesis design for7. Desjardins RP. Obturator prosthesis design for
acquired maxillary defects. J Prosthet Dentacquired maxillary defects. J Prosthet Dent
1978;39:424-32.1978;39:424-32.
8. Fiebiger GE, Rahn AO, Lundquist DO, Moise8. Fiebiger GE, Rahn AO, Lundquist DO, Moise
PK. Movement abutments by removable partialPK. Movement abutments by removable partial
denture frameworks with a hemimaxillectomydenture 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. Clinical9. 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.

Maxillofacial Prosthetics Classification and Design

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (20)

Destaque

Destaque (6)

Semelhante a Maxillofacial Prosthetics Classification and Design

Semelhante a Maxillofacial Prosthetics Classification and Design (20)

Mais de Indian dental academy

Mais de Indian dental academy (20)

Último

Último (20)

Maxillofacial Prosthetics Classification and Design