maxillofacial

2. RETENTION IN
MAXILLO FACIAL
PROSTHESIS
Presented by
Dr R Padmini Rani
P.G Trainee
Department of prosthodontics
KIDS

3. Contents
• Introduction
• Intraoral consideration
• Extra oral consideration
• Conclusion
• References

4. INTRODUCTION AND DEFINATION
• Maxillofacial prosthetics is a branch of prosthodontics in dentistry.
Main aim is to restore the function and esthetics of an individual.
• Its also approves a psychological state of a patient after a trauma or
surgery
• MAXILLOFACIAL PROSTHETICS -The art and science of anatomic,
functional, or cosmetic reconstruction by means of nonliving
substitutes of those regions in the maxilla, mandible, and face that
are missing or defective because of surgical intervention, trauma,
pathology, or developmental or congenital malformations.- GPT 9

5. TYPES OF MFP
• Extraoral-
• Intraoral - Mostly functional- mandible
Maxilla
Mostly cosmetic- nose
orbit
Ear

6. • Maxillofacial prosthesis is retained through various methods for their
retention and support.
• Each retentive mechanism is having its own advantage and
disadvantage.
• The various retentive aids available are 1) adhesive, 2) skin tapes/
straps/ suture material/ toupee tapes, 3) spectacle frames, 4) soft
tissue or bony undercuts, anatomic projections using them as
mechanical interlocks and 5) implants.
• These retentive aids are selected based on the various factors such as
the extent of prosthesis, availability of bone, patient’s dexterity,
location, amount of hard and soft tissue available and compliance and
prognosisof the patient.

7. RETENTION
INTRAORAL EXTRAORAL
ANATOMIC MECHANICAL
ANATOMIC MECHANICAL
TEMPORARY
S.S wire PERMANENT
Clasps
Preformed bands/crowns
Clasps
Precision attachments
Overlay, swing lock
Adhesives
Magnets
implants
Eyeglasses
Magnets
Buttons
Adhesives
Implants etc

8. INTRAORAL RETENTION
MECHANICALANATOMIC
TEMPORARY PERMANENT

9. Intraoral retention ( anatomic)
Include use of
Hard tissue soft tissue
• Residual maxillary retention- alveolar ridge and teeth
• Within the defect retention- residual soft palate, hard
palate,anterior nasal aperture,lateral scar band

10. Residual maxilla retention
• Utilization of the physical properties
• Ridge size and shape
• The palatal contour
• premaxillary segment or the tuberosity

11. Within-the defect-retention
• Large defects contribute intrinsically to the retention of the obturator
prosthesis .
• There are intrinsic areas within and around the defect that can
provide retention like
• The residual soft palate
• The residual hard palate
• The anterior nasal aperture
• The lateral scar band

12. Residual soft palate
• Extension of the obturator prosthesis on to the nasopharyngeal side
of the soft palate will provide retention

13. Residual hard palate
• Depending on the of the line of palatal resection
• Undercut along this line into the nasal or paranasal cavity.
• Engagement of the medial wall of the defect can increase retention.

14. Anterior nasal aperture
• This can be entered unilaterally or bilaterally.

15. Lateral scar band
• The skin superior to the junction tends to stretch creating an area
above the scar band that can be engaged by the obturator prosthesis.
• This minimizes vertical displacement of the prosthesis

16. • Retention is like a castle held together by proper Support and
Stability. If any one fails the whole castle comes crumbling down

17. SUPPORT
• It is the resistance to movement of a prosthesis toward the tissue.
• The support available from the residual maxilla and from within the defect
• 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 structure that provides a firm base like
• the floor of the orbit,
• the bony structures of the Pterygoid plate,
• the anterior surface of the temporal bone
• The nasal septum

18. STABILITY
• It is the resistance to prosthesis displacement by functional forces.
• Residual maxilla stability: If natural teeth remain, the bracing
components of the prosthesis framework can be used to minimize
movement in all 3 directions.
• In edentulous patients, maximal extension into the mucobuccal fold
Within-the defect stability: Maximal extension of the prosthesis in all
lateral directions must be provided.
• Maximum contact possible with the medial line of resection, the
anterior and lateral walls of the defect, the pterygoid plates, and the
residual soft palate must be established.

19. Occlusion
• The most important aspect of stability is occlusion.
• Maximal distribution of the occlusal force in centric and eccentric jaw
positions is imperative to minimize the movement of the prosthesis
and the resultant forces to individual structures.
• The patient with an acquired maxillary defect should not masticate
over the defect.

20. Review of literature (Prosthodontic principles in the framework design of
maxillary obturator prostheses
Gregory R. Parr, DDS,a Greggory E. Tharp, DMD,b and Arthur O. Rahn, DDSc )
• The Aramany classification system of postsurgical maxillectomy
defects is a useful tool for teaching and developing obturator
framework designs and enhancing communication among
prosthodontists.
• This article describes a series of Aramany-obturator design templates
and discusses the relevant considerations for each.
• In all situations, a quadrilateral or tripodal design is favored over a
linear design because this allows a more favorable leverage design
application that will aid in the support, stabilization, and retention of
the prosthesis. (J Prosthet Dent 2005;93:405-11.)

25. MECHANICAL RETENTION (intraoral)
Temporary Permanent

26. Temporary mechanical retention
• Stainless steel wrought wire of 18 gauge size .
• some preformed wire clasps can be readily incorporated to acrylic
plate of prosthesis.
• Preformed stainless steel wire clasps include Adams , arrowhead ,
Akers or Hawley labial wire

27. Permanent mechanical retention
• Cast clasp other forms
• Circumferential clasp
• Cast wrought clasp
• Combination clasp
• Roach Akers clasp
• Ring clasp

29. CAST CLASP
• The clasp extends into an undercut of the supporting tooth in order
to gain retention.
• The most common method for retaining a prosthesis is the use of cast
metal clasps. There are many different types of cast metal clasps e.g.
cast circumferential clasp, ring clasp and I- Bar clasp .

30. Permanent mechanical retention
clasp other forms
Attachments
Adhesives
Magnets
implants
Swing lock device
Spring Screws
Suction

31. Attachments
• Precision attachment can be described as a retainer used in fixed and
removable partial denture construction consisting of a metal
receptacle and a closely fitting part, the former is usually contained
within the normal or expanded contours of the crown of the
abutment tooth, and the latter is attached to a pontic or to the
denture frame work.

32. PREFABRICATED PRECISION ATTACHMENTS
• Attachments can be placed into cast crowns for the best esthetic and
mechanical retention.
• Most useful in rehabilitating cleft lip and cleft palate cases .
• They are prefabricated machined components with precisely
manufactured metal to metal parts with close tolerance.

33. SEMIPRECISION ATTACHMENTS, CUSTOM MADE
Semiprecision attachments -“Laboratory fabricated rigid metalic
extension (patrix) of a fixed or removable dental prosthesis that fits
into a slot type key way (matrix) in a cast restoration allowing some
movement between the component”. – GPT 9
Semiprecision rest – intracoronal rest seat and resilient lingual arm.
Gillete (1923) : The first semiprecision attachment
This attachments are formed in the wax pattern, using a specially
shaped mandrel mounted on the parallelometer .

34. AUXILLARY ATTACHEMENT
Screw units Bolts Frictional devices Hinged flanges
Lack of adjustment potential renders intracoronal frictional attachment unsuitable for
removable prosthesis, as repeated insertion and removal will cause the attachment to
wear.
Auxiliary retentive features are incorporated in some attachments in an effort to
provide more retention for a given frictional area
They serve these situations
• Allows planning which will enable the clinician to remove the prostheses for repair or
conversion.
• Overcome alignment problems which arise when abutments converge, making it
impossible to prepare them so that they can be mutually withdrawn when
constructing fixed partial dentures.
• Replace the loss of soft tissue in anterior fixed partial dentures. Supplements
retention on bars and telescopic crowns.

36. STUD ATTACHEMENTS
• E.g. Dalla bona , Rotherman
 Advantages
• Easy to adjust
• Less leverage
Disadvantages
• Cannot be use with limited space

37. BAR ATTACHMENT
E.g. Dolder and header
 Indication
• Bone loss around abutment
Advantages
• Rigid splinting and
• cross arch stabilization
Disadvantages
• Difficult to maintain oral hygiene

38. SNAP-ON ATTACHMENT
• It is a preformed precious- metal precision piece designed to retain
and to stabilize a prosthesis.
• A Baker bar or Anderson bar is the rod connecting two abutment
crowns, and the clip engages this rod.

39. BAKER SNAP-ON ATTACHMENTS
SOLDERED TO THE CAST FRAMEWORK
CROSS-ARCH SPLINTING USING 11-
GAUGE BAR SNAP-ON ATTACHMENT

40. OVERDENTURES
• Improved retention may be obtained by one of the several
attachment devices or by lining the overdenture with one of the
resilient denture liners to utilize available tooth undercuts.

41. OVERLAY (TELESCOPING) CROWN AND THIMBLE
CROWN
• This type is used when an overlay denture is planned or an extremely
malposed tooth is needed for stability.
• It is also indicated when a major change in the vertical or centric
dimension occur , as in cleft lip-cleft palate, and prognathic mandibles

42. SWING-LOCK ATTACHMENTS
• Swing-lock partial denture design using long flexible arm to engage
anterior and posterior abutment teeth.
• The swing-lock design should not be used at all unless splinting of the
posterior teeth is first accomplished.

43. MAGNETS
• Small steel magnets are embedded beneath the molar and premolar
teeth of upper and lower dentures and arranged with similar poles
opposite each other.
• At least two magnets are required for the lower denture and four
magnets for the upper denture.
• This effective method of retention may be useful in cases of hemi-
maxillectomy, or extremely atrophied ridges. The use of magnets in
two piece prosthesis is advocated.

44. • Matsamura et al (2000)
described fabrication procedure
of a removable sectional denture
connected by a cobalt-samarium
magnetic retention system for a
patient with severe maxillary
defect

45. USING OF SPRINGS
• The opposing arch can be used to assist in the retention of the
maxillary prosthesis by attaching a spiral spring to the prosthesis in
the premolar region.
• These spiral springs are made of coiled stainless steel or gold-
plated base metal and have their ends attached to swivels in the
premolar areas on both sides of upper and lower dentures.

46. • Nylon springs of continental origin are available and have the
advantage of being thin and not collecting food .
• Their life is limited to about six months, and the method of their
attachment to the denture, which is a nylon ball and socket joint, is
not very efficient. If this were improved they would be very
satisfactory.
•

47. • The disadvantages of nylon springs are:
• 1-The constant pressure may cause excessive alveolar absorption
• 2-The mucous membrane may not tolerate the constant pressure.
• 3-The inner surfaces of the cheeks may become sore from frictional
contact with the springs.
• 4-Lateral movements are extremely restricted.
• 5-Collecting foods and become unhygienic.

48. ADHESIVES

49. • These materials improve fit, comfort and retention of the prosthesis
by producing a high viscous layer between the denture and its
supporting tissues.
• This material is necessary to aid retention in the following cases:
• a- Large surgical wound.
• b- Flat palate.
• c- Nonexistent maxillary tuberosities.
• d- Missing of soft tissue undercuts in the area of surgery.
• e- Diminished salivary flow due to pre-and postredication therapy.
• f- loss immediate upper denture due to alveolar absorption

51. • The requirements of adhesives are
• 1. Highly adherent;
2. Nontoxic—that is, nonirritating to the tissues;
3. Elastic at the point of contact to the skin;
4. Non injurious to the prosthesis;
5. Highly durable;
6. Easily cleansed from the surface of the prosthesis as well as from
the soft tissue involved.

52. • Disadvantages
• 1-It gives a temporary
retention .
2-It has an unpleasant feel
when pressed out from
beneath the denture.
• 3-It is of little use for retaining
lower dentures.
4-Its constant use may cause
constipation.
• The troubles with adhesive
• Difficult to clean
• They collect dirt and are unhygienic
• Unreliable (swimming, sweating or greasy skin)
• Awkward to position correctly
• The application of the adhesive may be messy
and time- consuming.
• The edges of the prosthesis must often be
thickened or reinforced with fabric to resist
tearing that may occur as the adhesive is
cleaned from the prosthesis on a daily basis.
• The adhesive may cause skin irritation,

53. Technique to remove adhesive
• Adhesive remover -Adhesive remover are used to remove adhesive
from the skin .e.g. plastic remover , acetone
• Cotton bud is socked in remover and apply slowly under and around
the fitting surface of the prosthesis.

54. IMPLANTS IN THE INTACT SIDE
• Improved retention may be obtained by one of the several
attachment which can be used with the implants.

55. EXTRAORAL RETENTION
MECHANICALANATOMIC

56. Anatomic retention
The dynamic extra-oral retention depends on many factors.
These factors are related to
• the size and location of the defect,
• tissue mobility,
• undercuts and
• the weight of the prosthetic material.

57. • The hard tissue act as a base and provide a better seal of the
prosthesis with the use of adhesive.
• Examples would be any bony wall of a defect with which part of the
prosthetic device will come in contact or a cartilaginous remnant of
the ear.
• Soft tissues prove to be more troublesome because of their flexibility,
mobility, lack of bony nasal support, lower resistance to displacement
when a force is applied, deficiencies as a base for firmly securing the
surgical adhesive during cementation.

58. • SM Parel discussed a method to use anatomic under cuts in
conjunction with flexible conformer in the defective space as a
mechanical retentive feature in an orbital prosthesis

59. Mechanical retention
• Current mechanical means for
retention of facial prostheses include:
1. Eyeglass:
Parr GR5 proposed a possible means
of retaining a nasal prosthesis by
utilizing newly designed eyeglass
frames for the patients who has had
the bridge of the nose surgically
removed. The eyeglass frame should
be opaque in color rather than
translucent to prevent retention
marks from becoming visible.

60. 2.Magnets
• Magnets in maxillofacial Prosthesis have been used for decades to
reconstruct large defect .
• Federick(1975) rehabilitated a patient with large orofacial defect
using a 2-component obturator that was locked to each other with
the help of magnets.
• Tsutsui H et al found Samarium – Cobalt magnet to be remarkably
superior in magnetic properties to other kinds of magnets and stated
cobalt-samarium is not chemically harmful.
• Angelini E et al (1991) investigated the corrosion resistance of the
palladium – cobalt ferromagnetic alloy (constituent of the keeper
cemented on the abutment teeth) coupled with the samarium –
cobalt magnets embedded in the removable part of the prosthesis,
strong corrosive attacks were not observed.

61. • Grant GT et al (2001) described a procedure for the fabrication of an
extraoral prosthesis with an acrylic resin substructure that retains a
magnet sealed from the environment by a polyurethane liner .
• Yoshida K et al (2008) treated two female patients with orbital defects
after malignant tumor resection using custom-made retentive
components of an individual magnet for an Epitec System orbital
prosthesis.

63. 3.Acrylic buttons and retentive clips:
• Acrylic buttons – retained facial prostheses usually have an acrylic
substructure that fits into the defect and one or more mushroom –
shaped acrylic projections (buttons) attached to the substructure.
• The final prosthesis is fabricated so that it will snap over the
mushroom buttons for retention.
• Retentive clips are metallic or plastic clips that snap over the bar used
as a superstructure connected to the implants. Retentive clips have
more retentive ability in terms of breakaway retentive force than
magnets.

64. 4. Implants
• Intraoral implants to retain dentures and other prosthetic
replacements for missing teeth has led to use of implants to retain
extra oral structures.
• Jacobsson et al (1988) reported nearly 83% success rate for implants
placed in irradiated bone sites
• Seals RR jr et al described fabrication and support for facial
prostheses by using osseointegrated implants.
• Wolfaardt JF et al mentioning the demerits of adhesives proposed
placement of two implants with the bar designed to minimize
torquing on the implants and to facilitate hygiene.

65. Indication
• Extra oral implants are used for retaining eye
, ear and nose maxillofacial prosthesis .
• Patient with cartilaginous or peripheral tissue
or thick layer of skin
Contraindication
• Poor immune defense
• Use of steroids
• Neoplasm as a result of chemotherapy
• Uncontrolled endocrinopathy
Relative contraindication
• Diabetes mellitus
• Irradiated bone or ongoing
radiotherapy
• Inflammation of implant site

66. Retention system in extra oral implant
• Osseointegration implants in craniofacial reconstruction improves
prostheses retention , stability , comfort and safety for a patient .

67. Bar clip attachment
• Most commonly used
• metallic bar clip system present expensive laboratorial procedure
Advantages
• Good load distribution on the implants.


68. Disadvantages
• risk of damaging the bar during construction of prosthesis
( JPD 1996 vol 76 page 603)

69. Magnet systems
• Consists of a magnet cap that is threaded
onto the abutment and a magnet is placed
onto the tissue surface of the prosthesis.
Indicated
• When abutment are not parallel
• In orbital and auricular prosthesis with or
without bar clip system
• Swallow defects with insufficient space for
a bar and clip attachment .

70. Advantages
• Ease of removing and inserting
• Makes the wearing and daily care beneficial
• Easy hygiene control
• Reduce probability of infection

71. Ball attachment system
• Three implants creating a tripod
• Provide satisfactory retention and stability
• Indication
• Shallow defects as they occupy less space
behind the prosthesis .
• Advantages of ball system
• Induces less stress to implant • Absence of bar optimizes more
hygiene • Provides freedom of movement
• Disadvantages
• Wear of the rubber ring

72. Slant lock system
• Based on active engagement
• System provides security to patient because the prosthesis keeps in
position until the system is unlocked .
•
• Disadvantages - Silicone tear

74. Implant for orbital prosthesis
• Superior , lateral , and inferior rims are
possible site for implant .
• 3 to 4mm implants are needed.
• Scherer UJ et al (1995) described a
new implant position site using
autogenous iliac bone graft and placed
the implant in axial direction in the
middle of the orbit.

75. • For the large defect it is best to connect the abutment with a bar .
( JPD 1993 70 329-332)

76. Auricular defect • McCartnay J (1991) described an
auricular prosthesis in which
osseointegrated implants were
placed in the temporal bone and
used a screw retained magnetic
alloy casting to retain an acrylic
resin magnet keeper, to which
silicone ear prosthesis was
attached.
• Dib LL et al (2007) satisfactorily
placed a porous surfaced
extraoral implant into bone
transplanted from the iliac crest
for auricular prosthesis.

77. • Bar can be extended 10 to15mm
• Two retention system are used gold alloy
bar , and magnets
• In gold bar system 2mm gold cylinder is
attached to the abutment .
• Retention clip system incorporated into
prosthesis providing attachment to the
bar .
• Excellent retention for the prosthesis .
• However it may limit the access for
performing hygiene procedures , require
extension of the base of the prosthesis to
cover the bar .

78. • Second retention technique is use of magnets .
• Magnets are connected to abutment.
• 6mm diameter and 2mm thickness .
• The bar structure must be designed to contain housings to hold
magnets
• Corresponding magnets are placed within the silicone prosthesis .
• Alternative technique employed only the use of magnets
• This technique employs a magnet keeper that connects directly to the
abutment thus elimination the need for a retaining bar

79. Nasal defects
• Implant can be placed in maxillary or frontal bone
• 4mm implants are required
• Positioned in each lateral rounded nasal eminence
• The prosthesis is completed before the placement of implant .
• Position of the abutments and the retentive elements do not
compromise the contours of the prosthesis
• Bowden JR et al described two patients in whom zygomaticus
implants had been used to aid in salvaging prosthetic reconstruction
of the nose after rhinectomy

80. • Split thickness graft is needed .
• The septal cartilage must be reduced surgically
• Provide room for the prosthesis to engage the lateral walls of the
defect
• Increase stability of prosthesis

81. Implant design for maxillectomy defect
Potential Implant Sites
• Residual premaxillary segment
• Residual posterior alveolar ridge -Sinus lift and graft
• Maxillary tuberosity
• Zygoma -Normal side/ Defect side

83. Implant design for midfacial defect
• Midfacial defects often result from ablative procedures used to
control malignancies of nasal & maxillary structures.
• As the size of defect increases, complexity of prosthetic rehabilitation
increases.
• Jenson DT et al (1992): - Described available sites for the implant
placement in the midfacial region
• Suggested craniofacial site classification for the osseointegrated
implants – alpha, beta & delta sites
Zygoma, anterior maxilla and mandible are the alpha sites
in craniofacial region.
Periorbital but also in the
temporal, zygomatic, and anterior
nasal fossa locations.
Buttress, pyriform, zygomatic arch, medial orbit,
temporal and frontal bones, and zygomatico frontal
process.

85. Advantages of implants
• Aesthetic is better
• Implant simplify the cleaning procedures
• Life of prosthesis is long
• Implant retained prosthesis have provided the opportunity to
participate in routine activities .
• Provide ability to function in society with confidence

86. CONCLUSION
• Maxillofacial prosthesis is difficult to retain, and clinician should
employ creative ways to enhance retention.
• Combination of different methods can maximize retention, and
overcome disadvantages with the other method.
• Careful selection of the patient, and customization of retention
techniques considering esthetic, functional, social, and economic
factors is important for a successful outcome.
• Also more research is needed in the areas of prosthetic materials,
adhesives, and techniques to accomplish success.
• Bottom line is technology is nothing without human imagination.

87. THANK YOU

88. References
• Beumer J, Curtis TA ,Firtell DN Maxillofacial Rehabilitation
• HAROLD PRISKEL, Precision attachment in prosthodontics
• Gurjar, Rajesh & Kumar, Sunil & Rao, Harikesh & Sharma, Alok & Bhansali,
Sumit. (2011). Retentive Aids in Maxillofacial Prosthodontics -A Review.
• Chandran R (2017) Maxillofacial Implants... A Revolu on in Reten on of
Maxillofacial Prosthesis. J Ora Med Vol.1 No.1:7
• M.V. Cobein, N.P. Coto, O. Crivello Junior, J.B.D. Lemos, L.M. Vieira, M.L.
Pimentel, H.J. Byrne, R.B. Dias, Retention systems for extraoral maxillofacial
prosthetic implants: a critical review, British Journal of Oral and Maxillofacial
Surgery, Volume 55, Issue 8,2017,
• Sema Murat, Gurbuz Ayhan, Isayev Abulfaz, Dokmez Bahadir, Cetin Unsun.
Enhanced retention of a maxillofacial prosthetic obturator using precision
attachments: Two case reports. Eur J Dent. 2012;6(2):212–217.