Guide to Overdentures

OVERDENTURES
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
1www.indiandentalacademy.com

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DEFINITION:
Overdenture is defined as a removable partial
denture or a complete denture that covers and rests
on one or more remaining natural teeth, the roots of
natural teeth, and/or dental implants.

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RATIONALE OF OVERDENTURES:
Retention of any tooth for an overdenture preserves
a portion of one of the major sensory inputs i.e.
input from the periodontal propioceptors, which
contain information about the magnitude and
direction of the occlusal forces as well as about the
size and consistency of the food bolus. This along
with the input of other receptors in the mouth,
muscles, TMJ contribute to the overall response.
The periodontal receptors input are also protective
against occlusal overloading. Extraction of all teeth
results in total loss of all input from periodontal
ligament receptors; where as use of an overdenture
preserves the sensory input.www.indiandentalacademy.com

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The natural anterior teeth give more discreet
sensory input, but posterior teeth should also
be retained for overdentures whenever feasible
even though their sensory input is lesser.
It is also known that the retention of teeth
for overdentures provide better sensory feed
back regarding masticatory performance.
The use of an overdenture preserves
alveolar bone, especially in the area of the
retained teeth.

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Advantages of overdentures
Equally effective and superior method of
treatment
Simplicity of construction
Ease of maintenance
Stability
Retention
Esthetic excellence
Open palate possible
Reasonable cost
Familiar Procedures
Ease in making measurements
Ideal Occlusion
Excellent patient acceptance

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Less trauma to the supporting tissues
Stabilization of existing structures
Minimal adjustment
Possibility of using attachments or soft liners
Transitional or training dentures
Conversion to complete denture
Reversibility
Ease in Cleaning
Proprioceptive response
Distribution of forces of mastication
Fewer post insertion problems

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Disadvantages of overdentures
The overdenture treatment is more expensive
than conventional denture treatment due to the
endodontic therapy usually required and the
subsequent restoration of the teeth with alloys or
gold copings. Frequently teeth to be retained
also need periodontal therapy.
The overdenture is bulkier than the fixed or
removable partial dentures.
Many patients do not like any removable
appliance and therefore may prefer a fixed partial
denture. www.indiandentalacademy.com

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If the patient does not keep the retained roots or
teeth and the overdenture clean, caries and
periodontal disease may progress.
Maintenance problems:
Copings may become loose
Attachment wear, loss and breakage
Alveolar ridge resorption
 Overdenture breakage
 Oral hygiene problems

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Indications:
Younger the patient greater the indication
In situations where retention is difficult to
obtain
a. Absence of alveolar residual ridge
b. Xerostomia
c. Loss of maxilla or partial loss of
mandible
d. Congenital deformity (i.e. Cleft palate)
For patients with poor prognosis for complete
dentures
a. High palatal vault and ridge slope
b. Poorly defined sublingual fold space
c. In class III tongue patients
d. Knife edge ridge

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When pronounced vertical overlap is required to
produce the desired esthetic result.
Unilateral overdenture can be given to provide
good function and esthetics when a large
amount bone and soft tissues have been lost on
one side of the arch
Patient with badly worn out teeth.
When complete denture will be opposed by
retained mandibular anterior teeth preventing
combination syndrome.

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Contraindications:
Uncooperative: Under motivated patients
Psychologically some patient cannot accept
removable prosthesis
Mentally and physically compromised
When patient cannot economically afford

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Contraindications for Endodontically involved teeth
Contraindications for periodontally involved teeth
• Uncorrectable soft tissue and osseous
defects
• Failure to establish sufficient zone of
attached gingiva
• Class III Mobility
• Vertical fracture
• Mechanical perforation of root
• Broken instrument
• Horizontal fracture of root below bony
crestwww.indiandentalacademy.com

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Oligodontia
Types of over dentures
I. Overdentures for congenital and acquired
defects:

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Class III Patient with missing teeth

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Patient with eroded teeth

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II. Transitional overdentures:
A Transitional or interim overdenture is made
from an existing removable partial denture, the
patients own teeth or from both. Frequently, the
entire procedure can be done while the patient
waits, or part of it can be done before the
extraction visit. The objective is to do the most
for the patients with the least of trauma.

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III. Immediateoverdentures
An immediate overdenture is an overdenture
constructed for insertion immediately after the removal
of natural teeth. It may be used as an interim
prosthesis. The immediate overdenture enables a
dentist to use a simplified construction technique that
allows flexibility in planning treatments as requirements
change. Many times with good oral hygiene and
regular professional supervision an immediate
overdenture may have a long life. Sometimes, it can
be a prognostic aid before a more comprehensive
overdenture procedure. If prognosis is poor and
response to treatment is poor and immediate denture
can be converted into a serviceable complete denture.

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IV. Remote overdentures
A remote overdenture is an overdenture other
than transitional or immediate. It is usually
constructed for insertion at sometime remote
from the removal of hopeless natural teeth.
The remote overdenture usually placed on well
healed ridges usually after a period of
satisfactory experience with an interim
overdenture which may be transitional or
immediate. Although remote overdentures can
be entirely constructed of resin, metal bases
are frequently used.

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Metal base overdentures:
A metal base overdenture is complete denture
with a cast metal base that is supported and
stabilized by selected natural teeth with contours
that are modified for the purpose by preparation
and placement of copings.

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Metal base Overdenture

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V. Removable partial denture:
A superior removable partial overdenture can
be made for may patients by reducing some
of the remaining teeth coronally so that the
prosthesis can be fabricated over them.
Tooth preparation Removable partial
overdenturewww.indiandentalacademy.com

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VI. Implant overdentures
A wide variety of implant types and procedures have
been used with an overdenture as the means of a
final restoration. The osseointergrated approach of
implants with its use of titanium metal and rather
sophisticated techniques of placement has proven to
be viable and worthy procedure. Although it is used
mostly with fixed type of prosthesis, on occasion
single fixtures are placed on each side of the midline
and an overdenture is fabricated over fixture.

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DOWEL DESIGNS
There are mainly 5 categories:
1. Customized cast dowels
2. Prefabricated resin patterns
3. Prefabricated metal dowels
4. Threaded dowels
5. Dowel systems

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1.CUSTOMIZEDCAST DOWELS
When a dowel and coping are waxed together and
cast as a unit the discrepancy is the same as when
making an inlay and crown in the same casting. If
the expansion for the coping were sufficient, the
dowel would be oversized, the coping could not
seat, and the dowel could fracture the root during
either try-in or cementation because of the wedge
effect and the hydrostatic pressure of the cement.
This factor can be reduced by preparing cement
-release groove down the long axis of the dowel. If
the dowel were undersized, the coping would seat
properly, but the dowel would be retained by
cement only.www.indiandentalacademy.com

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2. PREFABRICATEDRESIN PATTERNS
The prefabricated dowel patterns are provided
with a matched set of burs for preparing the
dowel space. The cross sectional strength of a
pattern dowel is considerably less than that of a
prefabricated metal dowel of the same size, for
the metal dowels are drawn from a high fusing
alloy, different than that used for the copings, and
do not have the potential porosity and fracture of
a cast dowel.

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3.PREFABRICATEDMETAL DOWELS
The prefabricated metal dowels have a big
advantage over the two previous systems because of
the exact fit and high metallurgic strength in the cross
sectional area; they require minimal enlargement of
the canal space and strengthen the tooth rather than
weaken it. The prefabricated metal dowels have
matched sets of burs for exact fit of the preparation.
The dowels are machined from high-fusing wrought
metal that is specially alloyed for dowel usage. Most
of these dowels have cement release grooves, which
avoid the possible risk of incomplete seating or root
fracture during cementation.

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4.THREADEDDOWELS
Threaded dowels provide mechanical fixation in
addition to cementation. The VK and Kurer
systems offer excellent retention with the
threading.
5.DOWEL SYSTEMS
Schenker step pivot (European). V K and Kurer system

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CLASSIFICATION OF OVERDENTURES
Heartwell:
I . Noncoping
II. Coping
III.Attachments
I. NONCOPING OVERDENTURES:
Selected abutments are reduced to a coronal
height of 2 to 3 mm and then contoured to a
convex or dome shaped surface. Most teeth
require endodontic therapy followed by amalgam
or composite restoration.

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II.COPING OVERDENTURES:
Coping Types
A coping fitted to a prepared abutment is called a
primary coping. The sleeve, or coping, that fits
over this primary coping is referred to as a
secondary coping.
There are four basic types of primary copings:
1. Long copings (6-8 mm).
2. Medium copings (4-6mm).
3. Medium-short copings (2-4 mm).
4. Short copings (1-2 mm).

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1. Long Copings (6-8 millimeters for vital teeth):

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2. Medium Copings (4-6 millimeters for vital and
non-vital teeth):

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Abutment preparations
for medium copings
Medium copings

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With bar attachments To engage plunger
Studs cantilevered

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3. Medium short copings (2-4 mm for nonvita
teeth):

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4. Short Copings (1-2 millimeters for non-vital
teeth):

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III. Overdenture with Attachments:
The attachments essentially increase the crown-
root ratio and then torque. Or apply horizontal or
vertical dislodging forces to the root abutments.
Here, low caries index, proper home care,
periodontal health and inter ridge distance are
absolutely necessary.

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TELESCOPE CROWNS:
The telescope crown is a prosthodontic retainer for a
fixed or removable prosthesis and usually consists of the
conical preparations with a like casting and a secondary
telescope casting that is embedded in a prosthesis or is
an abutment or crown itself. It is a system used to
stabilize an overdenture where 4 mm or more of clinical
crown is available. The advantage of the telescope
crown or telescope preparation over the standard
overdenture is the increased stabilization and retention of
the denture while using remaining vital or nonvital teeth
without dowels or screws.

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TELESCOPE OVERDENTURE:
The telescoped overdenture is an excellent alternative to
routine complete dentures. As the name implies, a
telescoped overdenture fits over natural teeth with that
portion of the overdenture fitting like a sleeve. These
supporting abutments may simply be endodontically treated
teeth reduced slightly, shaped, smoothed, polished and left
in this manner to support this denture; or, these roots or
teeth may be restored with metal copings. The size of
these primary copings, the copings on the teeth, may be
medium or long. They may be designed only to provide
support, or to provide support and retention.

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Advantages:
1. Conserve the alveolar ridge
2. Provide support and often retention
3. Retains some natural proprioception
4. Emotionally accept the overdenture
5. Easy modification possible
6. Auxiliary retention devices can be added
7. Easy to master
8. Less expensive than attachment fixation
overdentures
Disadvantages:
1. Retention is fixed, and not variable
2. Retention must be modified frequently
3. The overdenture is bulky and less esthetic
4. Expensive than a conventional complete denturewww.indiandentalacademy.com

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ATTACHMENTS CAN BE CLASSIFIED
ACCORDING TOSHAPE, DESIGN, AND
PRIMARY AREA OF USE AS FOLLOWS:
(Mensor)
Coronal
1. Intracoronal attachments
2. Extracoronal attachments
Radicular
3. Telescope stud attachments (pressure
buttons)
4. Bar attachments
a. Joints
b. Units www.indiandentalacademy.com

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Accessory
5. Auxiliary attachments
a. Screw units
b. Pawl connectors
c. Bolts
d. Stabilizers/balancers
e. Interlocks
f. Pins/screws
g. Rests

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The GerberAttachment
The Gerber stud system is a versatile stud attachment
used routinely. It consists of a male post soldered to
the coping and a retentive female secured within the
denture base of the overlay prostheses. The Gerber
attachment is furnished in two different types - a
resilient and non-resilient form.
Resilient Gerber Non resilient Gerberwww.indiandentalacademy.com

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The male post consists of two
parts - a threaded base,
which is soldered to the
diaphragm of a coping, and a
removable sleeve with a
retentive undercut
The resilient female consists of
a housing, coiled spring, C-
spring, a retention sleeve and
lock screw. The non-resilient
female has a female housing, C
spring and a screw cap and no
copper shim and coil spring.

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Dalla Bona Attachment
The Dalla Bona is a simple stud attachment making an
excellent overdenture attachment available in a
resilient or nonresilient series. It is useful when there is
minimal vertical space and where rotation, resilience
and retention are desired. It consists of a single piece
male stud soldered to the coping and a single unit
female processed within the denture. It is available in
two types:
1.Cylindrical
2.Spherical
One form even has an internal coiled spring much like
the resilient Gerber. This spring helps control vertical
movement. The Dalla Bona series is an excellent
attachment.

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Dalla bona attachments on
two cuspids makes it
excellent overdenture
arrangement
Spherical Bona with
undercut for retention

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Male is a solid stud, female
is a single component with
retentive lamellae. A clear
Teflon ring covers the
female lamellae
Restored roots with
copings and spherical
bonas

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Cylindrical Dalla Bona
The cylindrical male post has parallel walls
without an undercut. The female lamella fits
snugly over the male posts, providing frictional
retention. A PVC ring fits around the female
lamellae. This aids in fabrication, and permits
the lamellae to flex. The cylindrical Dalla Bona
must be parallel; therefore, the male posts
must be assembled using a paralleling
mandrel and surveyor.

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Spherical Dalla Bona
The spherical Dalla Bona is similar to the
cylindrical, but the male post is spherical. This
sphere provides a retentive undercut which is
engaged by the retentive lamellae of the
female. If a spacer is used during fabrication,
this attachment will be resilient; without the
spacer, it will be nonresilient.

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The Rotherman Attachment
The Rotherman is another excellent stud attachment.
The Rotherman consists of a solid stud (that is soldered to
the coping) and a clasp like female (that is mounted in the
overdenture. Like many stud attachments, it is available in
both resilient and nonresilient designs. The resilient form
has a taller male and is supplied with special spacers.
The Rotherman is particularly applicable where
interocclusal space is limited, as the nonresilient design
has a vertical dimension of just 1.1 millimeter and the
resilient just 1.7 millimeter.

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BAR ATTACHMENTS
As the name suggests, bar attachments consist of a
metal bar that splints two or more abutments and a
companion mechanism processed within the tissue
area of the overdenture. This mechanism snaps on
the bar to retain the prosthesis.
Bar attachments are available commercially in a
wide variety of forms or they can easily be "custom"
fabricated.

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Types of BarAttachments
Bar units
Bar joints

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The Bar Unit
This bar has parallel walls providing rigid fixation
with frictional retention. It can be used for
retention with long, medium or short copings, but
only when the appliance is to be an all tooth
supported appliance (i.e. where no stressbroken
or rotational action is indicated). It is never used
when a bar joint is indicated (when rotational or
vertical action is necessary); however, a bar joint
can be used whenever a bar unit is indicated.

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The Bar Joint
The action of this attachment provides rotational or
vertical movement. In other words, it is a stress
broken attachment. It has a rounded or semi
rounded contour so the retention clip and prosthesis
can rotate slightly during mastication.

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The Dolder Bar
An ideal bar attachment is the Dolder bar. It is well
designed for splinting two or more abutments to
provide support, stability and retention for the
overdenture.
This bar attachment is manufactured in two forms
a bar joint and a bar unit. It is also available in two
different diameters and lengths.

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Dolder bar joint
The pear shaped bar joint is designed to provide vertical and
rotational action so it is indicated where a stress-broken,
resilient attachment is desired. It can also be used as a bar
unit for an all tooth supported prosthesis by fabricating the
overdenture without planned vertical movement.
Dolder bar unit
The bar unit is in the form of
an inverted U with parallel
walls. It does not permit
rotational or vertical
movement; therefore it only
provides retention and
support, but maximizes the
masticatory load on the
abutments.

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The Hader Bar System
The Hader system is an excellent bar attachment.
Similar to the customized bar, the Hader system
consists of a plastic bar pattern with gingival
extension and small plastic clips that are
processed into the overdenture. This system has
some advantages over others; the plastic bar
pattern's gingival extension can be trimmed to
conform to the ridge. In addition, worn clips can be
easily replaced at chair side using a special
seating tool.

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AUXILLARY ATTACHMENTS
In addition to bars and studs, other attachment
systems are applicable for overdenture
prostheses. These auxiliary attachments may be
in the form of screws or spring loaded plunger
attachments.

www.indiandentalacademy.com 59

Guide to Overdentures

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Guide to Overdentures