Principles and concepts of designing obturators/ orthodontic seminars

Principles And Concepts OfPrinciples And Concepts Of
Designing Obturators In DentateDesigning Obturators In Dentate
SubjectsSubjects
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

INTRODUCTIONINTRODUCTION
 The presence of a palatal defect can causeThe presence of a palatal defect can cause
functional, aesthetic and social distress forfunctional, aesthetic and social distress for
patients.patients.
 The provision of a suitable prosthesis thatThe provision of a suitable prosthesis that
obturates the defect presents clinical andobturates the defect presents clinical and
technical challenges to the clinician, but intechnical challenges to the clinician, but in
recent times useful progress in the provision ofrecent times useful progress in the provision of
satisfactory obturator appliances has beensatisfactory obturator appliances has been
made.made.

DEFINITIONDEFINITION
The name obturator is derived from the LatinThe name obturator is derived from the Latin
verb “verb “obturare”obturare” which means close or to shut off.which means close or to shut off.
According to the glossary of prosthodonticAccording to the glossary of prosthodontic
terms obturator is defined as prosthesis used toterms obturator is defined as prosthesis used to
close a congenital or an acquired tissue opening,close a congenital or an acquired tissue opening,
primarily of hard palate and or contiguous alveolarprimarily of hard palate and or contiguous alveolar
structures..structures..

HISTORYHISTORY

 Ambroise Pare (1541) : probably the first
person to close a defect.
 In one variation of his device a dry sponge
was attached to the upper surface of the disc.
When the sponge becomes moist by the
secretion it expands and hold the prosthesis in
place.
 In another variation he used turnbuckle type
of mechanism to hold the prosthesis in place.

Pierre Fouchard (1728) :
Father of modern
dentistry contributed
significantly to
maxillofacial prosthetics.
He described two types
of palatal obturators.

 One of the types has a
wings in the shape of
propellers which can be
folded together while
being inserted and
spread out after
insertion with a special
key.

In the other type, the retainingIn the other type, the retaining
feature is in the form of afeature is in the form of a
butterfly wings which arebutterfly wings which are
made to open by a key after themade to open by a key after the
closed wings have beenclosed wings have been
inserted through the palatalinserted through the palatal
perforationperforation.

MATERIALS USED FOR OBTURATORMATERIALS USED FOR OBTURATOR
 Primitive man used stone, wood, gum, cotton, toPrimitive man used stone, wood, gum, cotton, to
obturate the defect.obturate the defect.
 Towards the end of the nineteenth century,Towards the end of the nineteenth century,
vulcanite proved value in prosthodontics andvulcanite proved value in prosthodontics and
maxillofacial prosthetics and replaced most ofmaxillofacial prosthetics and replaced most of
the earlier materials.the earlier materials.
 Gelatin : gelatin glycerin compound (Gelatin : gelatin glycerin compound (byby
Hennig)Hennig) was developed and was widely usedwas developed and was widely used
during and after the first world war.during and after the first world war.

 The most common material used for theThe most common material used for the
fabrication of the intra and extra oral prosthesesfabrication of the intra and extra oral prostheses
are polymeric in nature.are polymeric in nature.
 These includes : vinyl chloride polymer andThese includes : vinyl chloride polymer and
copolymers, acrylic types and silicon rubberscopolymers, acrylic types and silicon rubbers
(heat-vulcanizing and room temperature(heat-vulcanizing and room temperature
vulcanization (RTV) type).vulcanization (RTV) type).

FUNCTIONS OF AN OBTURATORFUNCTIONS OF AN OBTURATOR
The obturator fulfills many functions:The obturator fulfills many functions:
 It can be used to keep the wound or defectiveIt can be used to keep the wound or defective
area clean, and it can enhance the healing ofarea clean, and it can enhance the healing of
traumatic or post surgical defects.traumatic or post surgical defects.
 It can help to reshape or reconstruct the defect.It can help to reshape or reconstruct the defect.
 It also improves or in some instances makesIt also improves or in some instances makes
speech possible.speech possible.
 In important area of esthetics the obturator canIn important area of esthetics the obturator can
be used to correct lip and cheek position.be used to correct lip and cheek position.

 It can benefit the morale of patients withIt can benefit the morale of patients with
maxillary defects.maxillary defects.
 When deglutition and mastication are impaired,When deglutition and mastication are impaired,
it can be used to improve functions.it can be used to improve functions.
 It reduces the flow of exudates into the mouth.It reduces the flow of exudates into the mouth.
 The obturator can be used as a stent to holdThe obturator can be used as a stent to hold
dressing or packs postsurgicallydressing or packs postsurgically.

General principlesGeneral principles
1.1. Need for a rigid major connector.Need for a rigid major connector.
2.2. Guide planes and other components thatGuide planes and other components that
facilitate stability ad bracing.facilitate stability ad bracing.
3.3. A design that maximizes supportA design that maximizes support
4.4. Rests that place supporting forces along theRests that place supporting forces along the
long axis of the abutment tooth.long axis of the abutment tooth.

5. Direct retainers that are passive at rest andDirect retainers that are passive at rest and
provide adequate resistance to dislodgementprovide adequate resistance to dislodgement
without overloading the abutment teeth.without overloading the abutment teeth.
6. Control of occlusal plane that opposes the6. Control of occlusal plane that opposes the
defect, especially when it involves naturaldefect, especially when it involves natural
teeth.teeth.

BASIC OBJECTIVES OF AN OBTURATORBASIC OBJECTIVES OF AN OBTURATOR
 It should be comfortable.It should be comfortable.
 Should restore adequate speech, deglutition,Should restore adequate speech, deglutition,
and masticationand mastication
 Should be acceptable cosmetically.Should be acceptable cosmetically.
 To achieve all these objectives, the obturatorTo achieve all these objectives, the obturator
should have adequate support, retention andshould have adequate support, retention and
stability.stability.

Indications of obturator:Indications of obturator:
 To act as framework over which tissues mayTo act as framework over which tissues may
be shaped by the surgeon.be shaped by the surgeon.
 To serve as temporary prosthesis during theTo serve as temporary prosthesis during the
period of surgical correction.period of surgical correction.
 To restore a patients cosmetic appearanceTo restore a patients cosmetic appearance
rapidly for social contacts.rapidly for social contacts.
 When patients age contraindicates surgery.When patients age contraindicates surgery.

 When local avascular condition of tissuesWhen local avascular condition of tissues
contraindicates surgery.contraindicates surgery.
 Inability of the patient to meet theInability of the patient to meet the
expenses of surgery.expenses of surgery.
 When patient is susceptible to recurrenceWhen patient is susceptible to recurrence
of original lesionof original lesion..

RATIONALERATIONALE
The need for the study of obturator design wasThe need for the study of obturator design was
evident because ofevident because of
(1) The increase in the number of partially(1) The increase in the number of partially
edentulous patients undergoing partial resectionedentulous patients undergoing partial resection
of the maxilla,of the maxilla,
(2) The increase in the life expectancy after(2) The increase in the life expectancy after
surgery, creating a need for definitivesurgery, creating a need for definitive
restorations, andrestorations, and
(3) An ever-increasing percentage of younger(3) An ever-increasing percentage of younger
patients in the maxillary resection patientpatients in the maxillary resection patient
population.population. www.indiandentalacademy.com

CLASSIFICATIONCLASSIFICATION
 To discuss metal framework design forTo discuss metal framework design for
maxillectomy patients in a systematic manner,maxillectomy patients in a systematic manner,
In 1978 the late Dr Mohammed AramanyIn 1978 the late Dr Mohammed Aramany
presented the first published systempresented the first published system
classification of postsurgical maxillary defects.classification of postsurgical maxillary defects.
 The classification is divid-ed into six differentThe classification is divid-ed into six different
groups based on the relationship of the defectgroups based on the relationship of the defect
area to the remaining abutment teeth.area to the remaining abutment teeth.

Classification for partially edentulous maxillectomy dental arches: Class I, Midline
resection. Class II, Unilateral resection. Class III, Central resection. Class I V, Bilateral
anterior-posterior resection. Class V, Posterior resection. Class VI, Anterior resection.

Class IClass I
The resection in thisThe resection in this
group is performed alonggroup is performed along
the midline of the maxilla;the midline of the maxilla;
the teeth are maintained onthe teeth are maintained on
one side of the arch.one side of the arch.
This is the most frequentThis is the most frequent
maxillary defect, and mostmaxillary defect, and most
patients fall into thispatients fall into this
category.category.

Class IIClass II
The defect in thisThe defect in this
group is unilateral,group is unilateral,
retaining the anteriorretaining the anterior
teeth on theteeth on the
contralateral side.contralateral side.

Class IIIClass III
The palatal defect occurs
in the central portion of the
hard palate and may
involve part of the soft
palate.
The surgery does not
involve the remaining
teeth..

Class IVClass IV
The defect crosses the
midline and involves
both sides of the
maxillae.
A few remaining
posterior teeth in a
relatively straight line

Class VClass V
The surgical defect in
this situation is bilateral
and lies posterior to the
remaining abutment teeth.

Class VIClass VI
rare
congenital anomaly/trauma
removes the entire
premaxillae

CONSIDERATON IN OBTURATORCONSIDERATON IN OBTURATOR
PROSTHESIS DESIGNPROSTHESIS DESIGN

SUPPORT:
Support gives the resistance to movement of
the prosthesis towards the tissue.
Support is available from
 Residual maxilla
 Within the defect

I. Residual maxilla support : includes:I. Residual maxilla support : includes:
A. Residual teethA. Residual teeth
1.carious involvement of the remaining teeth1.carious involvement of the remaining teeth
should be treated and their periodontal statusshould be treated and their periodontal status
made optimal.made optimal.
2.Support is also provided by the placement of2.Support is also provided by the placement of
occlusal rests, cingulum rest and incisal rest.occlusal rests, cingulum rest and incisal rest.

B. Alveolar RidgeB. Alveolar Ridge
1.Large, broad and square ridge provide better
support than the small, narrow ridge with a
tapering contour.
2.In patient with a retained premaxillary
segment or a tuberosity, the arch form is
improved and also the support.
3.The healthy well formed edentulous ridge
with extensive sulci will enhance support.

C. Residual Hard PalateC. Residual Hard Palate
1.The palate shelf is located perpendicular to the
direction of the occlusal stress and provides
considerable support during function.
2.The broad, flat palate is more supportive than the
high tapering palate.
3.Large palatal tori and pendulous soft tissues should
be removed because the process will require relief
and this will decrease the support.

IIII WITHIN THE DEFECT SUPPORTWITHIN THE DEFECT SUPPORT
It is necessary to prevent the rotation of theIt is necessary to prevent the rotation of the
prosthesis into the defect.prosthesis into the defect.
a.a. Floor of the OrbitFloor of the Orbit
Use of the floor of the orbit for support shouldUse of the floor of the orbit for support should
be minimal. It cannot be used for support, ifbe minimal. It cannot be used for support, if
orbital floor has been removed then the orbitalorbital floor has been removed then the orbital
contents will move with the movement of thecontents will move with the movement of the
prosthesis.prosthesis.

Drawbacks:
i)If prosthesis is extended up to the orbital
floor it would make insertion through the oral
opening difficult, unless a two piece sectional
prosthesis is used.
ii)Additional weight
iii)Problems of fabrication
iv)Alteration in speech quality due to too
much obturation of the resonating chamber.

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

RETENTIONRETENTION
Retention is the resistance to vertical
displacement of the prosthesis.
Retention is provided by
- Within the residual maxilla
- Within the defect

Residual Maxilla Retention is provided by
a. Teeth
i) If the defect is small and remaining teeth are
stable, intra coronal retainer can be used.
ii) If the defect is large and all teeth are weak,
extra coronal retainers should be used.
b. Alveolar Ridge
A large and broad ridge with flat palate is more
retentive than small ridge with tapering ridge crest
and high tapering palate.

Within the defect RetentionWithin the defect Retention Provided byProvided by
a) Residual soft palatea) Residual soft palate
i) Provides posterior palatal seal and preventi) Provides posterior palatal seal and prevent
ingress of food.ingress of food.
ii)Extension of the obturator prosthesis intoii)Extension of the obturator prosthesis into
the nasopharyngeal side of the soft palatethe nasopharyngeal side of the soft palate
provides retention.provides retention.

b) Residual Hard Palateb) Residual Hard Palate
--Undercuts along the line of palatal resection intoUndercuts along the line of palatal resection into
nasal or paranasal cavity or superolateral wall ofnasal or paranasal cavity or superolateral wall of
defect can increase retention.defect can increase retention.
-Obturator extension into the undercut is best-Obturator extension into the undercut is best
provided by a soft denture base material.provided by a soft denture base material.

c) Lateral Scar Band
For adequate surgical closure, most maxillary
resections are lined with split – thickness skin
graft along the anterior lateral and postero –
lateral walls of defects.
This results in the formation of scar band which
is more prominent in laterally and postero–
laterally as compared to scar band anterior to
premolar region.
These act as good undercuts for retention.

d) Height of lateral
wall

Engaging lateral wall
of defect provides
indirect retention.
 Longer radius
undergoes less vertical
displacement than the
shorter radius.

Quality of retention depends onQuality of retention depends on
 Muscular control.Muscular control.
 Size of surgical cavitySize of surgical cavity
 availability of tissue undercut around the cavityavailability of tissue undercut around the cavity
 Direct and indirect retention provided by anyDirect and indirect retention provided by any
remaining teeth.remaining teeth.

Retentive regions areRetentive regions are
 Fibrous tissue scar bands in the buccal sulcus.Fibrous tissue scar bands in the buccal sulcus.
 Rolled edge of the palatal remnantsRolled edge of the palatal remnants
 Base of the nasal mucosa of the nasal septum.Base of the nasal mucosa of the nasal septum.

Forces on ObturatorsForces on Obturators
These forces can beThese forces can be
 Vertical dislodging forceVertical dislodging force
 Occlusal vertical forceOcclusal vertical force
 Torque or rotational forceTorque or rotational force
 Lateral forceLateral force
 Anterior posterior force.Anterior posterior force.

Dislodging and rotational forcesDislodging and rotational forces
The weight of the nasal extension of the obturatorThe weight of the nasal extension of the obturator
exerts dislodging and rotational forces on abutmentexerts dislodging and rotational forces on abutment
teeth.teeth.
To resist these forcesTo resist these forces
-weight of the obturator be minimal-weight of the obturator be minimal
-direct retention-direct retention
-extending the buccal wall of the nasal-extending the buccal wall of the nasal
extension superiorly.extension superiorly.

Value of the lateral wall height in design ofValue of the lateral wall height in design of
partial denture obturatorpartial denture obturator
 As defect side ofAs defect side of
prosthesis is displaced,prosthesis is displaced,
lateral wall of obturatorlateral wall of obturator
will engage scar band andwill engage scar band and
aid in retaining theaid in retaining the
 Variance in verticalVariance in vertical
displacement which twodisplacement which two
different radius lengthsdifferent radius lengths
produce when arcingproduce when arcing
through a given horizontalthrough a given horizontal
dimension.dimension.

Relation of the scar band to the lateralRelation of the scar band to the lateral
portion of the obturator.portion of the obturator.
 Buccal scar band willBuccal scar band will
develop at height ofdevelop at height of
previous vestibuleprevious vestibule
where buccal mucosawhere buccal mucosa
and skin graft inand skin graft in
surgical defect join.surgical defect join.

Occlusal vertical forcesOcclusal vertical forces
 Activated during mastication and swallowing.Activated during mastication and swallowing.
 Wide distribution of occlusal rests will helpWide distribution of occlusal rests will help
counteract such forcecounteract such force

Lateral forces.Lateral forces.
It can be minimized byIt can be minimized by
 Covering the medial wall of the defect by aCovering the medial wall of the defect by a
palatal flap.palatal flap.
 Proper selection of the occlusal schemeProper selection of the occlusal scheme
 Elimination of premature occlusal contactsElimination of premature occlusal contacts
 Wide distribution of the stabilizing components.Wide distribution of the stabilizing components.

STABILITY:STABILITY:
Stability is the resistance to prosthesisStability is the resistance to prosthesis
displacement by functional forces.displacement by functional forces.
Stability is offered by:Stability is offered by:
i) Residual Maxilla Stabilityi) Residual Maxilla Stability
ii)Within the defect stabilityii)Within the defect stability

Stability of obturatorStability of obturator
 The terminal abutment teeth of the remaining archThe terminal abutment teeth of the remaining arch
determine the fulcrum line .determine the fulcrum line .
 2 lines are drawn from the fulcrum line to the2 lines are drawn from the fulcrum line to the
canine away from the defect,a stable triangle iscanine away from the defect,a stable triangle is
established.established.

 When the defect enlarges and the remaining palateWhen the defect enlarges and the remaining palate
and dental arc decreases, the area within theand dental arc decreases, the area within the
triangle diminishes, as does the stability of thetriangle diminishes, as does the stability of the

Residual Maxilla Stability:-Residual Maxilla Stability:-
 This is done by providing bracing components ofThis is done by providing bracing components of
the prosthesis frame work.the prosthesis frame work.
 Extending bracing interproximally will minimizeExtending bracing interproximally will minimize
rotational as well as anterioposterior movement ofrotational as well as anterioposterior movement of
the prosthesis.the prosthesis.
Within the Defect Stability:-Within the Defect Stability:- is provided byis provided by
 Maximal extension of prosthesis in all lateralMaximal extension of prosthesis in all lateral
directions.directions.

Class I.Class I.
Curved Arch FormCurved Arch Form

Aramany class I tripodal obturatorAramany class I tripodal obturator
design for curved archesdesign for curved arches

Class IClass I
linear arch formlinear arch form

Aramany class I linear obturator designAramany class I linear obturator design

Class IIClass II

Aramany class II obturator design.Aramany class II obturator design.

Class IIIClass III

Aramany class III obturator designAramany class III obturator design

Class IVClass IV

Aramany class IV obturatorAramany class IV obturator

Class VClass V

Aramany class V obturator design templateAramany class V obturator design template

Class VIClass VI

Aramany class VI obturator design templateAramany class VI obturator design template

Swing-lock design considerationsSwing-lock design considerations
 Swing lock framework:Swing lock framework:
GATE clasp – Ackerman in 1955 led to swingGATE clasp – Ackerman in 1955 led to swing
lock design which was introduced by Simmons.lock design which was introduced by Simmons.

Biomechanics of the Swing-lock designBiomechanics of the Swing-lock design::
 Movable labial / buccal bar– hinge at one endMovable labial / buccal bar– hinge at one end
– lock at the other end.– lock at the other end.
 Presence of a adequate vestibule. 4 tooth spanPresence of a adequate vestibule. 4 tooth span
– minimum bar length.– minimum bar length.
 Lock is separated from the nearest abutmentLock is separated from the nearest abutment
tooth by a one tooth space.tooth by a one tooth space.
 To ensure room for the first replacement tooth.To ensure room for the first replacement tooth.

 To allow the bulk of the lock to be within theTo allow the bulk of the lock to be within the
acrylic of denture.acrylic of denture.
 The hinge is placed lateral to but “in-line” withThe hinge is placed lateral to but “in-line” with
the dentition – no further posterior than thethe dentition – no further posterior than the
distal of the first molar.distal of the first molar.
 The lock is usually located on the side of theThe lock is usually located on the side of the
patients dominant hand.patients dominant hand.

Advantages of Swing-lock designAdvantages of Swing-lock design
 More stable than conventional prosthesis.
 Facilitates more complete sharing of the
functional load by all abutment teeth.
 Teeth even with questionable prognosis may
be used in S/L design.

 Used in situations where abutment alignment
incompatibility caused by tilting / rotation
would make conventional clasping difficult.
 Can be used when the absence of key
abutment teeth would make conventional clasp
retention inadequate

Disadvantage
 Can’t be used when the patient exhibits lack ofCan’t be used when the patient exhibits lack of
manual dexterity.manual dexterity.
 Increased need for recall and maintenance overIncreased need for recall and maintenance over
the conventional design.the conventional design.

Class I arch form:Class I arch form:
 Hinge is located nearHinge is located near
the posterior rest.the posterior rest.
 Retention is providedRetention is provided
by vertical struts thatby vertical struts that
contact all teeth incontact all teeth in
0.25mm undercut.0.25mm undercut.

Class II arch form:Class II arch form:
 For ovoid arches –
single Swing-lock
design.
 For tapering arches –
dual Swing-lock
design

Class III arch form :Class III arch form :
 Swing-lock is notSwing-lock is not
recommended unlessrecommended unless
a soft palatala soft palatal
obturator / a palatalobturator / a palatal
lift is also involved alift is also involved a
double Swing-lockdouble Swing-lock
design isdesign is
recommended.recommended.

Class IV arch form:Class IV arch form:
 Swing-lock designSwing-lock design
provides the mostprovides the most
stable and retentivestable and retentive
prosthesisprosthesis

Class V arch form:Class V arch form:
 Dual labial bar concept.

Class VI arch form:Class VI arch form:
Two designs:
 If posterior segment
contain at least 4 tooth
then a “double labial
bar”
 If posterior segment
contain less than 4 tooth
then a “dual labial bar”.

CONCLUSIONCONCLUSION
 Prosthesis design relative to all phases ofProsthesis design relative to all phases of
prosthodontics has been discussed by many authors.prosthodontics has been discussed by many authors.
 The need for support, retention and stability inThe need for support, retention and stability in
designating any prosthesis should be understood if thedesignating any prosthesis should be understood if the
objective of prosthodontic care is to be attained.objective of prosthodontic care is to be attained.
 For the patient with an acquired maxillary defect it isFor the patient with an acquired maxillary defect it is
often necessary to modify, and sometimes violate, someoften necessary to modify, and sometimes violate, some
of the basic principles of prosthesis design because ofof the basic principles of prosthesis design because of
the basic nature of the defect.the basic nature of the defect.

BIBLIOGRAPHYBIBLIOGRAPHY
 Clinical maxillofacial prosthetics –
Thomas D. Taylor
 Maxillofacial rehabilitation – John
Beumer
 Maxillofacial prosthetics – Chalian
 Miller, E. L.: Removable Partial
Prosthodontics. Baltimore, 1972, The
Williams & Wilkins Co

 Aramany, M. A.: Basic principles of
obturator design for partially eden-
tulous patients. Part I: Classification. J
Prosthet Dent 86:559-561, 2001.
 Aramany, M. A.: Basic principles of
obturator design for partially eden-
tulous patients. Part I: Design
principles. J Prosthet Dent 86:562-8,
2001.
 Desjardins, R.: Early rehabilitative
management of the maxillectomy
patients. J Prosthet Dent 38:311, 1977.

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