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Slide 1
Restoration of acquired defects of hard palate in dentate
patients Part II Hemant Jivnani JR II
Slide 2
Brief anatomy of the maxilla, the palate and the maxillary
sinus
Slide 3
Slide 4
Slide 5
How are Scars and scar contractures different?
Slide 6
Slide 7
Surgical considerations
Slide 8
Maxillectomy Several different subtypes of maxillectomy have
been described and due to the use of many terms like radical,
total, subtotal, limited, partial, medial, extended maxillectomies;
there has been a confusion regarding the nomenclature.
Maxillectomies can be classified according to spiro et al. based on
the number of walls as Limited: one wall Subtotal: at least two
walls including the palate Total : resection of the entire
maxilla
Slide 9
Slide 10
Browns classification
Slide 11
Surgeon should be advised the following considerations.
Slide 12
Line the reflected cheek flap with a split-thickness skin
graft
Slide 13
If the wound is allowed to epithelialize spontaneously, it
results in formation of poorly keratinized epithelium or
respiratory epithelium which can not be utilized to obtain support,
retention or stability for the obturator. While lining the defect
with skin graft provides a highly keratinized surface that can be
used to obtain support and retention for the obturator prosthesis
on the defect side.
Slide 14
Provide superior and lateral access to the defect
Slide 15
To remove the entire soft palate if less than one-third of the
posterior aspect of the soft palate is to remain post surgically.
(unless the patient is edentulous)
Slide 16
Imbibing the residual fibers of the levator veli palatini
muscle within the lateral wall of the pharynx can enhance the
residual velopharyngeal mechanism and an obturator can aid it to
achieve velopharyngeal closure during swallowing along with a
decreased hypernasality in speech.
Slide 17
Retain Premaxillary Segment
Slide 18
Save some of the palatal mucosa normally included in the
resection and use it to cover cut medial bone margin of the palatal
bones. Palatal incision Bony cut
Slide 19
CONSIDERATON IN OBTURATOR PROSTHESIS DESIGN
Slide 20
The need for support, retention and stability in designating
any prosthesis should be understood if the objective of
prosthodontic care are to be attained. For the patient with an
acquired maxillary defect it is often necessary to modify, and
sometimes violate, some of the basic principles of prosthesis
design because of the basic nature of the defect. The remaining
structure are most often unilateral, thus encouraging movement of
the prosthesis with associated stress directed to these remaining
structures.
Slide 21
The frequent location of unilateral remaining structures
suggests that the obturator portion of the prosthesis, in addition
to the residual structures, must contribute significantly to the
support, retention, and stability of the prosthesis to satisfy the
basic prosthodontic objectives.
Slide 22
Support is the resistance to movement of a prosthesis toward
the tissue. The support available from the residual maxilla and
from within the defect both must be considered. Residual maxilla
support In the residual maxilla the primary areas available for
support are the residual teeth, the alveolar ridge and the residual
hard palate. SUPPORT
Slide 23
A. Residual teeth Carious involvement of the remaining teeth
should be treated and their periodontal status made optimal.
Support is also provided by the placement of occlusal rests,
cingulum rest and incisal rest. Maximum effort should be directed
toward saving as many teeth as possible without compromising the
tumor resection protocol.
Slide 24
Within-the-defect support Positive support within the defect to
prevent rotation of the prosthesis into it must be considered. This
support can be achieved by contact of the prosthesis with any
anatomic structures that provides a firm base. In most acquired
maxillary defects the floor of the orbit, the bony structures of
the pterygoid plate, and the anterior surface of the temporal bone
near the infratemporal fossa are considered for positive
support.
Slide 25
a. Floor of the Orbit Use of the floor of the orbit for support
should be minimal. It cannot be used for support, if orbital floor
has been removed then the orbital contents will move with the
movement of the prosthesis. Drawbacks: 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.
Additional weight Problems of fabrication Alteration in speech
quality due to too much obturation of the resonating chamber.
Slide 26
b. Pterygoid Plate or Temporal Bone Positive contact of the
prosthesis with this bony structure can be relatively extensive and
adequate to tripod the support for an obturator prosthesis.
Slide 27
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.
Slide 28
Retention is the resistance to vertical displacement of the
prosthesis. Retention is provided by A. Within the residual maxilla
B. Within the defect A. Residual Maxilla Retention-is provided by
teeth in a dentate patient. 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. RETENTION
Slide 29
i) If the defect is small and remaining teeth are stable, intra
coronal retainer can be used. ii) If the defect is large and some
or all teeth are weak, extra coronal retainers should be used.
Slide 30
B. Within the defect retention Retention of an obturator
prosthesis cannot be totally and adequately provided by the
residual maxillary structures in either the edentulous or the
dentulous patient unless the defect in exceptionally small. Large
defects that approach the extent of the hemimaxillectomy must
contribute intrinsically to the retention of the obturator
prosthesis if the objectives of prosthesis design and prosthodontic
care are to be achieved.
Slide 31
If the obturator extension itself could minimize the vertical
displacement of the prosthesis, less stress would be generated to
the residual maxillary structures. The following structures should
be considered for retention within the defect. a) Residual soft
palate b) Residual hard palate c) Anterior nasal aperture d)
Lateral scar band e) Height of lateral wall
Slide 32
a) Residual soft palate Provides posterior palatal seal and
minimizes passage of food and liquid above the prosthesis.
Extension of the obturator prosthesis onto the nasopharyngeal side
of the soft palate provides retention.
Slide 33
B) Residual Hard Palate Under cuts along the line of palatal
resection into, nasal or para nasal cavity or medial wall of defect
can increase retention. Obturator extension into the undercut is
best provided by a soft denture base material. The extension
shouldnt contact the nasal septum or the turbinates
Slide 34
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.
Slide 35
D) Height of lateral wall Engaging lateral wall of defect
provides indirect retention. Longer radius undergoes less vertical
displacement than the shorter radius.
Slide 36
STABILITY Stability is the resistance to prosthesis
displacement by functional forces. Because function tends to move
an obturator prosthesis, the principles of obturator design that
minimize rotation around the horizontal plane and minimize movement
within the horizontal plane itself must be considered. Rotation of
the prosthesis around the horizontal plane is that rotation seen
around the fulcrum line. Many aspects of obturator design are
important to both retention and stability.
Slide 37
Movement of the prosthesis within the horizontal plane can be
anteroposterior, mediolateral, rotational, or a combination of any
or all of these directions. As with retention and support specific
areas of the residual maxilla, as well as the defect itself, must
be considered in minimizing the extent of these potential
movements. Residual maxilla If natural teeth remain, the bracing
components of the prosthesis framework can be used to minimize
movement in all three directions.
Slide 38
It is advantageous to provide maximal bracing and to extend
this bracing interproximally when possible to minimize rotational
as well as anteroposterior movement of the prosthesis.
Slide 39
Within the defect stability The defect itself must be
considered to enhance the stability of an obturator prosthesis.
Maximal extension of the prosthesis in all lateral directions must
be provided. Special emphasis must be placed on maximal contact
with the medial line of resection, the anterior and lateral walls
of the defect, the pterygoid plates, and the residual soft palate.
Contact of the obturator portion of the prosthesis with these
structures minimizes anteroposterior, mediolateral and rotational
movement of the prosthesis.
Slide 40
Occlusion Occlusion is a very important aspect for stability of
the prosthesis. an unstable prosthesis is the result if the
occlusal relationship fails to maintain intimate contact of the
prosthesis with the supporting and the retentive structures. To
minimize the movement of the prosthesis, maximum distribution of
occlusal forces is essential. Mastication over the defect should be
avoided.
Slide 41
Purpose of the prosthetic dentition on defect side: Esthetic
display Lip support Prevent opposing dentition from super- erupting
Occlusal scheme Centric only contact on the defect side is
preferred. Lateral interferences should be removed.
Slide 42
General considerations concerning the bulb design A bulb is not
necessary Small to average size defect Surgical or immediate
temporary prosthesis Need of hollow To aid in speech resonance
Light weight
Slide 43
It should not be high as to cause the eye to move during
mastication It should be closed superiorly always It should not be
large as to interfere with insertion if the mouth opening is
restricted.
Slide 44
Principles of framework design for obturator prosthesis
Slide 45
General requirements of the framework design for obturator
prosthesis, similar to that of a conventional removable partial
denture A rigid major connector. Guide planes and other components
that facilitate stability and bracing Rests that place supporting
forces along the long axis of the abutment tooth
Slide 46
Direct retainers that are passive at rest and provide adequate
resistance to dislodgment without overloading the abutment teeth
Control of the occlusal plane that opposes the defect, especially
when it involves natural teeth.
Slide 47
Unique considerations of the obturator framework The location
and size of the defect, especially as it relates to the remaining
teeth. The importance of the abutment tooth adjacent to the defect,
which is critical to the support and retention of the obturator
prosthesis. The usefulness of the lateral scar band, which flexes
to allow insertion of the prosthesis but tends to resist its
displacement and The use of the surveyor to examine the defect for
the purpose of locating and preserving useful undercuts or
eliminating undesirable undercuts.
Slide 48
Class 1- curved arch from Tripodal design is recommended if the
anterior teeth are to be used for support or retention Linear
design is recommended if the anterior teeth are not to be used for
support or retention. Support Support for the prosthesis can be
derived from: the remaining teeth, the residual palate, and the
structures in the defect that may be contacted.
Slide 49
Rests: on most anterior and the mesiocclusal surface of the
most distal abutment tooth when alignment and occlusion will
permit. The mesiocclusal posterior rest, most often located between
adjacent posterior teeth, is accompanied by a rest on the
distoocclusal surface of the more anterior adjacent tooth. Since
the prosthesis will first contact the undercuts and the other
support areas, during insertion and the teeth will be engaged
later, the prosthesis needs a compound path of insertion.
Slide 50
Guide planes will assist in the precise placement of the
prosthesis once the teeth have been contacted. They will also
ensure more predictable retention and add a greater degree of
stability to the prosthesis. Guide planes on the anterior abutment
should be kept to a minimum vertical height (1 to 2 mm) to limit
torque on the abutment teeth and should be physiologically
adjusted. This is important since movement can be expected during
function because of the extensive lever arm provided by the defect
and the dual nature of the support system.
Slide 51
An indirect retainer is usually located perpendicular to the
fulcrum line (which connects the most anterior and most posterior
rests) and as far forward as possible. This is usually a canine or
first premolar.
Slide 52
Retention Retention is supplied by direct retainer designs that
allow maximum protection of the abutment teeth during functional
movements. On the anterior abutment, a 19- or 20-gauge wrought wire
clasp of the I-bar design is often used to engage a 0.25-mm
undercut on the midlabial surface of this abutment.
Slide 53
CLASS I. LINEAR ARCH FORM 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. Retention Retention is usually provided by the combined
use of buccal premolar retention and lingual molar retention.
Slide 54
Class II This type of resection is favored prosthodontically
and should therefore be advised to the surgeon
Slide 55
Support- perpendicular to the fulcrum line rest is placed
Stability from palatal surfaces of abutments Retention from buccal
surfaces of the abutment teeth
Slide 56
Class III The design is based on quadrilateral configurations.
Support is widely distributed on both premolars and molars.
Retention is derived from the buccal surfaces and stabilization
from the palatal surfaces.
Slide 57
Class IV The design is linear Support on the center of all
remaining teeth. Retention -palatal on the premolars; buccal on the
molars. Stability - mesially on the premolars. palatally on the
molars.
Slide 58
Class V Tripodal configuration Splinting of at least two
terminal abutment teeth on each side is suggested. I bar clasps are
placed bilaterally on the palatal surfaces. Stabilization and
support are located on the buccal surface of the most distal
teeth.
Slide 59
Class VI 2 anterior teeth are splinted bilaterally and
connected by a transverse splint bar. A clip attachment may be used
without an elaborate partial framework. If the defect is large, or
the remaining teeth are in less than optimal condition, a
quadrilateral configuration design is followed.
Slide 60
Procedures for restoration of maxillectomy defects in a
dentulous oral cavity Impressions Impression for RPD framework
Altered cast Impression of the defect
Slide 61
Impression for RPD framework A stock tray is used. Periphery
wax is used to extend the tray into the defect and onto the soft
palate. The completed impression records the contours of residual
tissues, the dentition, and the defect. Undercuts on the medial
side of the defect should be blocked out. Otherwise the residual
palatal contours will be distorted upon removal of the tray.
Slide 62
Master cast is surveyed. The framework design is delineated on
the master cast and the framework is cast.
Slide 63
The framework is then tried in the mouth. Silicone disclosing
materials can be used to evaluate the intimacy of contact of the
framework to the tissues and to identify the pressure areas; and
necessary adjustment of the framework can be done.
Chloroform/halothane and rogue can also be used for the same
purpose, silicone being expensive. The framework should exhibit
satisfactory frictional fit to the teeth.
Slide 64
Altered cast impression Fabrication of an occlusal stop on the
oral side of the tray is recommended.
Slide 65
Border molding Use of low fusing compound for border molding
the defect. Anterior region is border molded first to stabilize the
denture base.
Slide 66
Movements Mandible: Wide opening Lateral Head Right to left
movement with neck in normal position Right to left movment with
neck flexed Right to left movment with neck extended
Swallowing
Slide 67
Incremental build up of the border moulding material can cause
unseating of the metallic framework leading to errors in
orientation of the defect to the residual maxilla, which can be
avoided by fabrcation of an occlusal stop on the impression tray
that records the defect and asking the patient to close on the stop
everytime the framework is inserted.
Slide 68
Wash impression The compound is cut back 1-2 mm to create space
for the wash material and thermoplastic wax is used to make a wash
impression and record the defect in functional position.
Slide 69
The impression is placed in the mouth and border molded.
Slide 70
Boxing and pouring of the altered cast
Slide 71
Slide 72
Centric relation records The occlusal indices made during the
altered cast impression can serve for mounting of the cast or
centric relation records can also be obtained By conventional
method
Slide 73
After mounting on a suitable articulator, teeth setting is done
keeping esthetics and the occlusal guidelines presented earlier, in
mind. The trial prosthesis is then tried in mouth and necessary
adjustments done. The quality of obturation is checked during the
try in stage by having the patient swallow water, and speech is
evaluated by having the patient pronounce m and b. Palatograms can
be used to improve the palatal contour to aid in speech.
Slide 74
Occlusion is achieved on the defect side, keeping in mind the
points discussed earlier. The prosthesis is processed in heat
polymerized acrylic resin. Finishing and polishing is done in the
usual fashion.
Slide 75
Conclusion The love our face is next only to the love of our
life and thus the mutilated cry for help As a prosthodontist our
aim should be to render the best service possible to the patient in
regard to the restoration and continuity of the defect to its most
natural form Basic knowledge of the technique, materials is the
basic requirements for any rehabilitation procedure
Slide 76
Which is not a surgical enhancement procedure for a
maxillectomy patient 1. Maintaining more contra lateral
premaxillary area 2. Maintaining the anterior alveolus and the
floor of the nose 3. Placement of a skin graft over denuded
surfaces 4. Resection of the inferior turbinate when the hard
palate is resected but the tumor does not involve the nasal
cavity
Slide 77
Treatment following resection of hard palate does not involve
1. Allowing the sinus walls to become load bearing 2. The palatal
bone screw can be placed through the acrylic resin baseplate in the
midpalate and secured to the middle turbinate 3. Avoid placing a
bone screw in the irradiated palate 4. Bone screws, sutures and
packing can be removed without sedation
Slide 78
Which of the following is false 1. Nasal reflux and hypernasal
speech is caused by continues fibrosis in the tissues bordering the
prosthesis 2. Improvement in swallowing and speech can be tested by
m and s sounds 3. Relining of the prosthesis will not alter
hypernasal speech when the soft palate is short in an
antero-posterior direction 4. Pharyngeal obturator extension can be
arbitarily shaped to extend into the pharyngeal opening over the
soft palate
Slide 79
Which is false when hypernasal speech occurs 1. Disclosure of
the bulb with tissue conditioning material often reveals that the
surface is inadequate 2. The prosthesis is adequately closed at the
periphery 3. Patients soft palate closure mechanism is not
functional 4. Patients pharyngeal closure mechanism is not
functional
Slide 80
Which of the following classification system does not involve
dental criteria for maxillectomy 1. Aramany, 1978 2. Okay, 2001 3.
Brown, 2000 4. Rodriguez, 2007