Obturator final / oral surgery courses

RETENTION OF
OBTURATORS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTS
           Introduction
       Definition
       Intra oral retention of obturators
•        Anatomic retention
•        Mechanical retention
        Temporary retention
        Permanent retention
     Extra oral retention of obturators
     Immediate surgical obturation

     Delayed surgical obturation
     Definitive obturation
•        total maxillectomy defect
•        partial maxillectomy defects
     Obturation of soft palate defects
     Meatal obturator prosthesis

     Snap-on prosthesis
     Resin-bonded components

     ERA attachment for swinglock obturator framework
     Mushroom-shaped resilient retainer
     Obturator overdentures retained by nonrigid attachments
     Implants as retaining elements
     Magnetic retention
     Conclusion
•   References

INTRODUCTION

An obturator (Latin: obturare, to stop up) is a disc or plate, natural or
artificial, which closes an opening.
      Prosthesis used to close a congenital or acquired tissue opening,
      primarily of the hard palate and / or contiguous alveolar structures.
(GPT8)
Post-surgical obturators :
(1) the immediate temporary obturator (also surgical obturator)
(2) the temporary obturator (also treatment or transitional)
(3) the permanent obturator
Retention of obturators
   maximal cooperation between surgeon and prosthodontist is necessary
   to achieve soft and / or hard tissue retention
1. Intraoral   Retention        anatomic
2. Extraoral  Retention        mechanicalwww.indiandentalacademy.comwww.indiandentalacademy.com

Intraoral Retention
Anatomic Retention :
•   hard and soft tissues,
•  the size and location of the defect
•  the outcome of the surgery
•  Anatomic undercut  -the palatal area, cheek,
retromolar, labial, septal, posterior nasal pharyngeal,
or anterior nasal spine areas
•   Large alveolar ridges and high palatal vaults
•  acquired undesirable denture habits.
•  Additional aids -  proper occlusion, proper post dam and
surface adhesion

Mechanical Retention :
Temporary Mechanical Retention
•  a stainless steel wrought wire ( 18)
•  preformed wire clasps incorporated into the acrylic palate or existing denture.
Adams, Arrowhead, Akers, Roach, or Hawley labial wires.
•  Preformed stainless steel bands or crowns
•  Extra soldered lugs or bands with prewelded brackets
•  old denture can be wired.
  retention is internal to the infraorbital or zygoma bones
Permanent Mechanical Retention :
Cast Clasps
• stability, splinting, bilateral bracing, reciprocation and retention
•successfully adapted - well designed, surveyed and fitted castings
•direct retainer
•180 degrees & an undercut or infrabulge area

Various qualities of clasp design influence the degree of retention.

Length -directly proportional to the cube of its length.
Diameter- inversely proportional to the fourth power of the diameter..
Form- tapered /uniform contour.
Material -wrought clasp / cast clasp, the cobalt – chrome alloys
Contour - half - round / round clasp arm
relative to its plane in space
The path of the clasp arm across the tooth surface may affect its load deflection
Depth of undercut employed
Reciprocating Clasp Arm
The lateral component of force
reciprocating support to the tooth on the opposite side
accomplished via a guiding plane with a more rigid clasp arm
remains in continuous contact
Occlusal Rest ; part of the direct retainer is that unit of the partial denture

frame designed specifically to fit within a prepared rest seat in the abutment
It serves several purposes www.indiandentalacademy.comwww.indiandentalacademy.com

Types of Extracoronal Direct Retainers :
Cast Circumferential Clasp (Akers clasp)
•reliability, ease of fabrication, and adaptability
•totally tooth – supported prosthesis and no tilting
leverages ,  modification spaces, opposite to unilateral
edentulous space.
•avoided on abutments adjacent to a free end saddle
replacement.
Cast – wrought Combination Circumferential Clasp.
•in a free end saddle situation.
•more susceptible to distortion
•anterior region
•greater adaptability than many of the cast clasps
T- Bar cast circumferential combination /
Roach- Akers clasp
•Cervical approach
•distobuccal undercut
•Distal extn cases
•Rotation of the base under load

Ring or Ring-around clasp
Uses undercut by circumnavigating the tooth
Lone standing molar abutment-tilted
Prefabricated Precision Attachment
Placed in to cast crown for best mechanical
retention
Cleft lip & cleft palate
Without reciprocal arm
Semiprecision Attachments, Custommade
This attachment -in the wax pattern
mandrel on the parallelometer
reciprocal arm
Snap-on attachment
Preformed precious- metal precision
Baker bar/ Anderson bar
Clasp , precision attachment or
thimble-telescopic crown www.indiandentalacademy.comwww.indiandentalacademy.com

Overlay telescoping crown and thimble-crown
Overlay denture
malposed tooth needed for stability
Major change in VD
& Centric dimension
cleft lip & palate
Magnets
Magnetised metal disc in denture teeth
Magnetised metal rod in ridge &
overlying saddle extn in denture
Nonstabile denture
Hemimaxillectomy/atrophied ridges

Gate type/ Swing lock device
Partial retention for periodontally involved
teeth
Intermaxillary “ George Washington” springs
Auxillary retentive devices
BL- Continuos clasp,valve seal,Faurchard wing
device for clefts ,guide planes,surface
adhesion,denture surface adhesion devices-
porceline & durabone www.indiandentalacademy.comwww.indiandentalacademy.com

Screws ;are made custom parts
Implants
Adhesives;
Large surgical defect,flat palate,
No –undercut AP lateral septal wall,tuberosities,soft
tissue undercut & less saliva
Occlusion. dictated by a healthy mandible and related to the motion sequence
recording from the healthy temporomandibular joint

Extraoral Retention :
Anatomic Retention
  the location and size of the defect, tissue mobility, undercuts, and  weight of the
prosthesis.
Hard tissues act as a base
                          better seal with the use of an adhesive. Ex- bony wall of a defect
Soft tissues
flexibility, mobility, lack of a bony basal support, lower resistance to displacement
when a force is applied, deficiencies as a base for firmly securing the surgical adhesive
during cementation, and the physiologic nature of squamous ectodermal tissues.
Mechanical Retention
Magnets - imbedded in a nasal prosthesis or orbital prosthesis to help secure it to a
maxillary obturator which may be in contact with the above prosthesis.
Snap Buttons and Straps -  large extraoral prosthesis.
Adhesives
aid retention, marginal seal, and border adaptation.
               This secures the prosthesis against accidental dislodgment.
Combination of Anatomic, Mechanical, and Adhesive Retention
Large facial replacements www.indiandentalacademy.comwww.indiandentalacademy.com

Immediate surgical obturation :
dentulous patients -well suited
•   the remaining teeth.
•   perforated at the interproximal extensions.
•   the existing complete or partial prosthesis
    flange reduced and the posterior  teeth removed
    Interim lining materials
•  wire retainers should engage sufficient
             no of teeth


edentulous patients
• wired or pinned to the alveolar
ridge , zygomatic arches or
anterior nasal spine
• minor occlusal discrepancies or
retentive deficiencies
• new application of interim
treatment liner
Delayed surgical obturation
In edentulous patients existing maxillary
prosthesis
•the prosthesis is adjusted
•an intermediate reline material
•the surgical obturator can be utilized to fabricate
the new restoration.
•relined periodically.

Definitive obturation :
•The defect engaged more aggressively for edentulous patients
Treatment concepts :
1. Movement of the prosthesis ;
displaced superiorly with the stress of mastication
    the number and position of teeth
    the size and configuration of the defect.
2. Tissue changes : at least a year - scar contracture and organization
       Movement of the prosthesis.
      obturator portion -acrylic resin ( rebased )

4 . Extension into the defect :
• the nasal septum & ciliated pseudostratified columnar
epithelium
• the lateral margin of the defect
• the skin graft and oral mucosa lining
5 . Teeth :
enhances the prosthetic prognosis.
Every effort to maintain teeth or even roots of teeth
6 . Weight :
Bulky areas
supporting tissues not stressed
hollow and lightweight
top surface –open/closed ? controversy ?www.indiandentalacademy.comwww.indiandentalacademy.com

Edentulous patient with total maxillectomy defects :
the axis of rotation
• most distant portion - greatest motion.
• premaxillary segment -moves posteriorly
• smaller defects• anterior resections- the axis posterior margin
• anterior lip margin -greatest movement.
• the residual palatal structures and by engaging the defect
Remaining palatal structure :
• Arch form- square or ovoid
• palatal shelf remaining
• residual alveolar ridge
• palatal shelf perpendicular to occlusal stress

The defect
• engaging key areas.
• edentulous - considerable movement
the skin graft-mucosal junction
• the scar band –
• undercut superiorly & concavity inferiorly
prominent posterolaterally
flexible but resist dislodging forces
• raw cheek surface -granulate and epithelialize
• appropriate obturator-tissue contact superolaterally.
• nasal surface of the soft palate & the nasal aperture
• vomer removed- undercut superiorly along
the medial margin
- flexible obturator

• Border molding
• Impression – scar band at skin graft –
mucosal juctn
• undercuts along the lateral and
lateral-posterior surfaces -vital
• most -rebasing within the first year
of delivery

Edentulous patients with partial maxillectomy defects :
• access to and use of the defect -impaired.
• Soft silicone materials
Mark A Pigno et al (2001)
obturator with extension into the nasal aperture
• the obturator fully seated
interim soft liner
withdrawn from the nasal aperture space
• stone matrix- recorded the space
acrylic resin - sprinkled into matrix
• an unconventional path of insertion
posteriorly ,anterior-superior
• allow adequate nasal breathing

• significant improvement in retention.
• an unfavourable unilateral maxillectomy defect in which
the nasal aperture space can be engaged to augment retention

Mushroom-shaped resilient retainer - Shogo Minagi et al
(1991)
•highly resilient silicone retainer
• composed- acrylic connector
round resilient wing
•absorb mechanical stresses
• use tissue undercuts effectively
than conventional hollow extension
•Renewability of the retainer
• ability of the nasal soft tissues poor

Dentulous patients with total maxillectomy defects :
prognosis improves with the availability of teeth
Kennedy class II partial denture with an extensive lever arm
Partial denture design
compound path of insertion
ex- lateral and posterior undercuts
inserted, rotated

• Retention -the physiologic limits of the periodontal
ligament
• crown - improved contours for retention, guiding planes,
and occlusal rests.
• anterior retainer and rest -orientation
rotate out of retentive areas posteriorly.
• Compromised abutment – overdenture abutment
• Multiple occlusal rests

Fulcrum line
• rests, size,configuration of defect
• arch form –taper-approximate the fulcrum
square –in line with rest
lingual retentive clasp arms
• prosthesis displaced superiorly-disengage
• greater motion around the fulcrum line
• the angulation of the abutment teeth
• no cross-arch reciprocation
• unilateral removable partial denture
• both buccal and lingual retentive arms
• “cross-tooth” retention and reciprocation
• lateral extn & 2 mm superior to the normal palatal contour.

Dentulous patients with partial maxillectomy defects :
• Kennedy class II partial denture
• the fulcrum line shifts posteriorly
• the distolateral extension -->mechanical advantage
• Indirect retainers - far anteriorly
• total maxillectomy pt - retainer adjacent to the defect
• defect need not be engaged aggressively

Bilateral total maxillectomy defect
• Surgically created undercut
• Silicone/ two piece prosthesis
Leanne M. Sykes et al (2002)
• roof of the patient’s mouth - skin graft
openings into the maxillary sinus
• thin acrylic resin obturator record base
• functional impression material –
extend 6 mm into the 2 oronasal openings
• extensions - in the final prosthesis.
• silicone resilient lining material
replaced with hard acrylic
• neutral zone
• oronasal communications

A new application of a screw-plate for prosthetic reconstruction
after bilateral total maxillectomy ; Juntunen K, Kullaa (1993)
obturator with finger clasps attached
to a classic AO-reconstruction plate
template - the contours of zygomas, buttresses
and the alveolar processes of the maxillae
.Infraorbital rims and bony orbital floors-intact
A preangulated classic AO-reconstruction plate
rigidly fixed to the zygomata
(four 2.7-mm cortical AO-screws)
situated near the zygomaticofrontal sutures.

•fitting the plate into its copy groove at
the inner acrylic base.
• The obturator -3 vertical finger clasps.
small as possible.
•number of screws - 4 on each side
•recent study -AO-THORP system
titanium plate and screw–plate-locking principle
final prosthesis

The hollow box maxillary obturator
Blair FM and Hunter NR (1998)
radical maxillectomy
obturator-lightweight
initially pt assessed for an implant retained
satisfactory conventional prosthesis
need for further surgery for implants

Total soft palate defect
•Partial denture design-long lever arm
•Multiple rests & retainers
•Distal undercuts
•Anterior edentulous areas- Dolder bar connecting 2
crowns(Indirect retainer)
•Thomson dowels
•Hand-crafted bar

Obturation of soft palate posterior border defects
•a wire loop attached to the conventional prosthesis
• soft palate exhibits little or no motion- cast
meshwork as a component of the partial denture
framework.

Meatal obturator prostheses :
• extends superiorly and slightly
posteriorly from the hard palate border
• extensive defects of the soft palate gag
reflex.
• the obturator of choice for edentulous pt
with poor retention
• downward displacement force from the
obturator extension is closer to the
supporting tissues of the parent
prosthesis.

Kiyoshi Shimodaira et al (1994) Obturator prosthesis conforming to
movement of the soft palate:
• soft palate defect and few teeth
• residual alveolar ridge and the soft palate
• extending impression for the nasal side of the soft palate
• obturator segment fabricated- wax on the duplicated cast
• 10 mm and 7 mm long
• placed at the nasal and oral surfaces across
anterior margin of soft palate
• soft silicone material
• Adhesive
• obturator prosthesis with small flexible silicone extensions

Magnetic retention : Kieth f. Thomas
• square samarium cobalt magnet -top surface
• vertical extension to the obturator bung -minimum
• removable acrylic stage.
• right angled - bonded to the silicone prosthesis.
• Magnets -always be gold plated /totally encapsulated in
acrylic.

Snap-on prostheses
marginal defects
• a snap-on removable partial prosthesis
• Multiple abutment teeth
• wax rod extensions
• bar rod is bent & soldered
with splinted crowns(1 or 2mm).
• Additional retentive means
Anterior segmental defect
•Transpalatal splinting
•Clip attachment -centrally

Resin-bonded attachments for maxillary obturator retention:
Yoav Grossmann et al (2004)
•resin-bonded cast-metal units
•designed to serve as guide planes
occlusal and cingulum rest seats
attachments, and splints
•Radical abutment preparation
and unesthetic clasps
•Castable spherical attachment patterns fixed
to the wax patterns at both ends of arch
• framework -intimately contact multiple tooth
•cast in base-metal alloy.
• attachment housing- joined to frame
The housings soldered to the frame
•The attachment plastic components
into the housings
•A closed hollow-bulb obturator (autopolymer)
•retentive buccal clasps avoidedwww.indiandentalacademy.comwww.indiandentalacademy.com

Thomas D Taylor et al (1988) resin-bonded components for
maxillofacial prosthesis construction : A clinical trial.
• 40 components in eight subjects
• cingulum rest seats, retentive undercut,
guide planes, and semiprecision attachments
retained resin-bonded retainer/rest seats
• the seven continued to wear prostheses
• Two - clasp adjustment at recall

•5 (12.5%) had lost adhesion. (etched-metal type and included two
guide planes and two splinted cingulum rests supporting a
semiprecision attachment (three components)
• 35 components have remained in place
used -inadequate access because of limited oral opening
crown preparation extremely difficult or impossiblewww.indiandentalacademy.comwww.indiandentalacademy.com

Principles
• Palatal guide planes -teeth unilaterally
• In bilateral situations- opposing retentive components
reciprocal components and minor connectors - single path
• straight line arch -unfavourable
rotational dislodgment
•short clinical crowns- palatal retention ineffective
curvature of the palatal surface < rotational path
• rotational arc depends occlusogingival placement of
buccal reciprocal element.
• Palatal guide planes parallel to the path of insertion
maximal occlusogingival height
• When indirect retention -across a fulcrum line, guide planes -lesser role

Implants as retaining elements
• Edentulous unilateral cleft lip & palate
• bone deficit
• Iliac bone graft
• Milled metal bar connecting endosseous mplants
• Fixed removable dental osseoprosthesis

• bilateral defect
• extencive Oral-nasal defect
• Implant uncovery stage 2 surgery
2 implants nonintegrated
• Cast metal bar

• Unilateral cleft palate
• Extencive oro palatal nasal defect
• Surgical closure ,no graft
• 6 implants &bilateral metal bars
ant ,inf to antrum
• Fixed removable overdenture with oral pharyngeal obturator

• Max antererior segmental defect
• 6 implants – 2 lateral in to zygoma body
2 tuberosity –pterygoid plate juctn
• Obturator with retentive devices

Thomas Weischer et al (1997) Titanium implants in the zygoma as
retaining elements after hemimaillectomy.
Hemimaxilectomy-extensive resection
obturator supported by periodontally involved teeth.
Malfunctional
5 endosseal implants -residual jaw
resection side of the zygoma
The zygoma implants- contralateral
anchoring
overstraining of retention posts
Extra long abutments capped with an obturator of silicone
. Zygoma implants -“accessory” retention

Meiko Oki (2002) A maxillary lip prosthesis retained by an
obturator with attachments: A clinical report.
•definitive obturator designed with 3 plastic ball attachments
•oriented in a triangular spatial arrangement
•fixed on the waxed denture and polymerized
• Impression around the lip with the obturator
.

1)
•The lip prosthesis -silicone.
•mechanical retention through ball
attachment
• lip prosthesis adapted well to functional
movements

Sectional prosthesis for total maxillectomy patients:
Russell R. Wang (1997)
•2 cm of soft palate remaining
•split thickness skin graft on the lateral wall sinuses
•Bone- inadequate for dental implants
•three-piece magnetically retained sectional obturator
•silicone putty sectional impression
• The light-activated acrylic resin base
• Two Sr-Co magnets -the middle of the defect
of resin base to provide an index for the second part

•Two additional magnets -in the peripheral area of first
•part of the obturator to engage the third segment
•Each segment inserted separately
•Magnets incorporated in denture base
•Adequate retention, stability, and support
•no denture adhesive
•proper midfacial esthetic contour

Antoniou DV et al (1996) Obturator prosthesis retention for edentulous
patients with large palatal defects:
left orbital and bilateral maxillary defects
extraoral retentive element -orbital communication defect
straight key attached to a rectangular extraoral plate
25 mm in length
through the opening in the orbital flap
obturator revised with resin –keyway
all three section inserted

• dislodgement of the key from keyway
• changing from a straight to a curved design
that arched in superior direction
•resisted straight horizontal dislodging motions
• distinctive orbital defect -extraoral retention
Esthetics not a primary concern.

magnetically connected removable sectional denture for a maxillary
defect with severe undercut Hideo Matsumura et al (2000)
• maxillofacial defects , microstomia, trismus,
or severe undercut in denture supporting
• 2-piece sectional RPD
severe undercut conflicted with the
path of insertion and withdrawal
• magnetic retainers -cobalt-samarium magnet
447J1 steel yoke&steel ring
air-abraded with 50 µm alumina
phosphate primer
embedded into the obturator
• obturator extension – connected to
the RPD framework with 4 magnets.
• a shallow retentive groove
• occasional dislodging www.indiandentalacademy.comwww.indiandentalacademy.com

techniques to further stabilize
1) additional retentive form at the edge of the obturator
2) extension of a bar or a connector from the obturator
toward the missing left side area,
3) cross bite arrangement of the right artificial teeth
• mechanochemical retention -retain magnets in the
Denture
• Newest version of magnetic retainer
• This magnetic retention system useful for interrelating and
retaining a sectional prosthesis parts.www.indiandentalacademy.comwww.indiandentalacademy.com

Incorporation of an ERA attachment for obturator framework
design : Elin Sigurgeirsdottis et al (2002)
• swinglock framework designs
• preformed metal hinge and locking precision attachments in a
single casting
• all remaining teeth- primary abutments
-wear of the metal latch assembly
ERA; sterngold, Attleboro
• ERA attachment as the latch
wear at the expense of the nylon
retention male component
interchangeable
• life of the latch assembly,
framework, and prosthesis

Female component aligned arc of closure the bar

Michael MacEntee (1997) Obturator-overdentures retained by
nonrigid attachments.
•Interim dentures : Hawley type of retainer
•supporting teeth - endodontic treatment
cast gold post
•Ceka male attachments - soldered to
cement post and copings

• Denture hollow bulb obturator
• Holes in the denture base
• female attachments placed
• attached to the denture base
• the roots of two teeth with attachments

Conclusion

References :
1. Maxillofacial prostheses, Varoujan A. Chalian
2. Maxillofacial rehabilitation, Beumer.
3. Prosthetic rehabilitation. Keith F. Thomas.
4.Osseointegration in craniofacial reconstruction –
Branemark
5. Dental Clinics of north America – Vol.34,No.2, April
1990.
6. J Prosthet Dent 2002;88:135-8
7. J Prosthetic Dent 1994;71(6):547-51.
8. J Prosthetic Dent 2004;92:229-32.
9. British Dental Journal 1998;184:484-487.
10.Int Oral Maxillofac Implants 1997;12:211-214.

11.J Prosthetic Dent 1996;76:227-9.
13.Clin Oral Impl Res 1993;4:47-50
14.Int J Prosthodont 1991;4:473-476.
20. J Prosthetic Dent 2002;87:477-80.
21. J Prosthetic Dent 2000;84:22-6
22.Prosthetic Dent 2002;88:362-6.

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