Overdenture / orthodontic straight wire technique

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

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INTRODUCTION:
Preventive Prosthodontics emphasizes the
importance of any procedure that can delay or
eliminate the future Prosthodontic problems. The
overdenture is a logical method for the Dentist to
use in preventive Prosthodontics. It is further
emphasized that alveolar bone with its overlying
mucosa was never intended to receive the full
force of complete denture. So, what is this
overdenture?

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DEFINITION:
G P T 1999,
1. 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.
2. A prosthesis that covers and is partially
supported by natural teeth, natural tooth roots,
and/or dental implants – called also Overlay
denture, overlay prosthesis, superimposed
prosthesis.

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He artwe ll,
A tooth supported complete denture is a
dental prosthesis that replaces lost or missing
natural dentition and associated structures of the
maxilla and/or mandible and receives partial
support and stability from one or more modified
natural teeth.

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History
The overdenture prosthesis constructed over existing
teeth or tooth structure is not a new concept in a technical
approach to a prosthodontic problem. Its use dates back
over 100 years.
In 1861, Barker reported on the proceedings of the
American Dental convention in New Haven, Connecticut.
Dr. Butler, Dr. Roberts, Dr. Atkinson, Dr. Sutton and Dr.
Hayes participated in a symposium entitled – “Surgical
preparation of the mouth for artificial dentures – should
the roots would enable fabrication of complete dentures
superior to that obtained after extraction of all roots.
Hayes reported the results of fabricating a complete
denture over two roots in the maxillary arches and 12
years later, they were still in place contributing to the
comfort of the patient.www.indiandentalacademy.com

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Since that convention, many more than hundred
journal articles on the retention of roots/teeth to
support a complete denture have appeared.
In 1945, Black of Louisville, Kentucky provided
complete denture for a 14-year old girl with a
congenital absence of the permanent teeth. Four
maxillary and four mandibular teeth were retained
and crowns were fitted to the molars. In 1972, 27
years later the mandibular deciduous molars were
still intact supporting a complete mandibular
overdenture.
During the Second World War, many dentists in
a military service used overdentures in the treatment
of inadequate or mutilated dentitions. Boos reported
such a treatment in the July 1948 issue of the Dental
Digest.

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In 1952, the article by Rehn advocated the
retention of a single front tooth for denture
support.
In 1958, Miller reported that retention of a
few teeth under complete dentures allowed the
weak teeth to regain healthy status. This
foresight was of prime importance in convincing
the profession that the overdenture was a
superior treatment modality. In 1969, Lord and
Teel reported 7 years of successful treatment
with overdentures.

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The Gerber series of root cap attachments was
developed in 1954 and for 20 years, clinically
successful hybrid prosthesis have been fabricated
with the Gerber attachments.
As new materials and products such as plastic
tooth material, soft liners, fluorides were introduced,
the potential for this type of treatment increased
materially. Methods were simplified and at present
overdenture, treatment can be provided at a little
additional cost over the conventional complete
denture.

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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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Studies show that 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.
Studies show that the use of an
overdenture preserves alveolar bone,
especially in the area of the retained teeth. In
this area, resorption occurs very rapidly after
extraction of teeth.

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Fromthe physiologic view point the rationale for
preserving tooth roots are:
1.SENSITIVITY OF ANTERIORTEETH:
Sensory input from the periodontal receptors is one
of the major determinants of masticatory function, and
the roots of the teeth offer more discrete discriminatory
input than does the oral mucosa. Retention of natural
teeth for an overdenture preserves some of the
sensory input from the periodontal receptors, which is
more precise than that able to be obtained from the
oral mucosa.

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Kawamura (1964), Grossman (1964), and
Grossman and associates (1965) agreed that
the sensitivity in the anterior part of the mouth,
particularly the periodontal ligament of the
anterior teeth, tongue tip, and mucosa, was
acute.
There is a greater concentration of sensory
receptors in the anterior part of the mouth
(Kawamura, 1964), and these signals from the
periodontal and mucosal receptors are
important in controlling and determining biting
force.

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2. DIMENSIONAL PERCEPTION:
Dimensional perception is the discrimination
of the different thickness of objects between the
occlusal surfaces of the teeth. Kawamura and
Watanabe (1960) found that patients with natural
dentition could discriminate differences at the 2
mm range better than those with artificial
dentures. These findings emphasized the
importance of conservative procedures and the
importance of the retention of natural teeth.

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3. CANINE RESPONSE:
Kruger and Michel (1962) said that the
canines have more neurons than any other
teeth. So, it acts as very important
proprioceptive organ which can lend support to
the retention for the overdenture.

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4. DIRECTIONAL SENSITIVITY
Jerge (1963, 1965) reported that the receptors
in the periodontal ligament were directionally
sensitive. He said that the receptors are arranged
around a tooth in such a way as to respond to
pressure regardless of the direction from which it is
applied. Directional sensitivity is one of the most
important elements in the interaction of the
masticatory system. It means that the periodontal
receptors have a functional individuality and that the
relationship of the tooth to its periodontal ligament is
highly important from a sensory standpoint.
Therefore, teeth should be retained for use with an
overdenture to preserve the directional sensitivity.www.indiandentalacademy.com

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5. PROPRIOCEPTION ANDSALIVARY
SECRETION:
Kapur and Collister (1970) studied food texture
discrimination and concluded that the periodontal
receptors played an indirect role in the masticatory
salivary reflex by regulating the range and type of
the masticatory stroke. They stated that absence of
the periodontal ligament in denture wearers
appeared to result in impairment of the mechanism
regulating parotid gland stimulation during
mastication.

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6. PERCEPTION OF NONVITAL TEETH:
The majority of natural teeth used to support
overdentures are devitalized and treated
endodontically. Perceptual studies showed that vital
and devitalized teeth had equal sensory input
capabilities (Stewart, 1927; Adler, 1947).
7. PERCEPTION OF TEETH WITH REDUCED
ALVEOLARSUPPORT:
Often teeth selected for use with overdentures may
have lost bone support. These studies showed that
the tooth still had a proprioceptive input capability
even though much of the bone support was lost.www.indiandentalacademy.com

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8. DECREASE OF PERCEPTION IN OLDER
INDIVIDUALS:
There is generalized decrease in
perception as age increases and the use of an
overdenture is an attempt to retain every
possible sensory element at the time the patient
may experience a generalized decrease in the
sensory capacity.

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Advantages of overdentures
Equally effective and superior method of
treatment: In many situations, overdenture gives
better service than alternative methods of treatment,
especially in patients with congenital defects
(oligodontia, microdontia, cleft palate etc.) and for class
III patients with a prognathic jaw not amenable to
surgical an orthodontic treatment.
Simplicity of construction: The procedure used in
constructing overdentures are the same as those for
complete dentures, and the retained teeth or roots
provide stability to the bases during registration of
maxillomandibular records. Also they aid in
determining the correct vertical dimension of occlusion
and in proper tooth placement.www.indiandentalacademy.com

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Ease of maintenance: Repairs,
alterations or refitting of the overdenture can
be done readily in the same manner as with
conventional complete dentures.
Stability: Stability is comparable to that
obtained with fixed or removable partial
dentures and the retention of four
abutments contributes greatly to this
stability.
Retention: Generally retention is excellent
because of the better stability of
overdentures.www.indiandentalacademy.com

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Esthetic excellence: The extensive selection of
artificial denture teeth and the many possible
arrangements for these aids in creating an
esthetic effect.
Open palate possible: The maxillary denture of
many patients can be roofless if necessary,
especially where anterior and posterior teeth are
saved
Reasonable cost: The time required for
creating an overdenture and thus the cost can be
less than for alternative procedures.

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Familiar Procedures: The procedure used are
similar to those used for conventional complete
dentures.
Ease in making measurements: When teeth
are retained for immediate overdentures, the
vertical dimensions of occlusion can be
maintained accurately.
Ideal Occlusion: Esthetically acceptable
occlusion can be provided.
Excellent patient acceptance: This is
attributable to the knowledge that the patient still
has his own teeth.

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Less trauma to the supporting tissues: The hard
tooth surface of the retained teeth supports the
dentures and inhibits resorption of the residual ridge,
which may occur when all the teeth are removed, and
conventional complete dentures provided. Less soft
tissue trauma also occurs.
Stabilization of existing structures: Although
tissues under a long span without tooth support may
resorb, little change occurs at the site of retained
teeth, thus maintaining the vertical dimensions and the
lip support.
Minimal adjustment: Little adjustment is required
due to the stability and support provided to the
overdenture by the retained teeth.www.indiandentalacademy.com

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Possibility of using attachments or soft
liners: This is done when soft tissue or bony
protuberances necessitate considerable relief of
the denture and it is difficult to maintain a seal.
Attachments or soft liners can be used.
Transitional or training dentures: Even
though the patient may loose the retained teeth
or roots or both in a short time the overdenture
is not only stable but also retentive for the
period of use, but is also excellent for
transitional or training in preparation for
receiving a complete denture.www.indiandentalacademy.com

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Conversion to complete denture: The
tissue coverage and border extensions are
usually the same for overdentures as for
complete dentures making it easy to
compensate for the loss of one or all of the
retained teeth. The spaces can be filled in or
the dentures can be relined or rebased.
Reversibility: When making overdentures
over a complete natural dentition, it may be
necessary to alter the existing teeth.
Therefore, the procedure is reversible, and
removal of denture puts the teeth back in their
original states.www.indiandentalacademy.com

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Ease in Cleaning: All surfaces of the
abutment are accessible to cleaning, and the
denture being removable is easier to clean than
a fixed partial denture.
Proprioceptive response: There is more
efficient neuromuscular coordination.
Distribution of forces of mastication: Forces
are distributed more uniformly over the roots
and denture supporting tissues.
Fewer post insertion problems: As
compared a conventional complete dentures.

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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 0r
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. Xerostomia
b. Absence of alveolar residual ridge
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
• Class III Mobility
• Uncorrectable soft tissue and osseous
defects
• Failure to establish sufficient zone of
attached gingiva
• Vertical fracture
• Mechanical perforation of root
• Broken instrument
• Horizontal fracture of root below bony
crestwww.indiandentalacademy.com

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Clinical evaluation
The examination includes: Patient history, Study
casts, clinical examination, and Radiographs. It is
very difficult to make a correct diagnosis to
determine if the overdenture is indicated for the
patient or the problems can be solved by alternative
techniques. This is ascertained by taking a proper
history of the patient’s medical background and past
dental history. The past dental history indicates the
patients experience with previous removable
appliances and his attitude towards the treatment.
Study casts accurately mounted on an articulator
show the occlusal relationship of the teeth and
arches, the vertical spaces between arches and
location of bony undercuts.www.indiandentalacademy.com

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They also help in determining the amount of tooth
reduction required, the types of coping and often the
types of attachments that can be used for particular
condition. Accurate study casts can also be used
for fabrications of interim overdentures when
necessary.
Clinical examination includes examination of the entire
oral cavity. All soft tissues are evaluated and teeth
are evaluated thoroughly. Occlusal relationships are
studied and periodontal and endodontic evaluation
is carried out. Potential abutments are evaluated for
mobility, crown root ratio etc.
Radiographic examination is done to evaluate
presence of pathological conditions, presence of
retained roots, bone loss, root curvatures, root
canals are noted.

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Diagnosis includes: Clinical evaluation and
selection of abutments, abutment location, bone
support, proximal space between abutments,
number of teeth available, masticatory load and
opposing dentition and the type/design of
prosthesis required.

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TREATMENT PLANNING:
The patient who has only few retainable natural
teeth may present difficult treatment questions for the
dentist. Johnston and associates (1965) stated that “a
bridge is indicated whenever there are properly
distributed and healthy teeth to serve as abutments,
provided these have suitable crown-root ratio and that
after radiographic, diagnostic cast and oral
examinations seem capable of sustaining the
additional load. When indicated, fixed partial dentures
are treatment of choice. A few retainable teeth
generally are scattered throughout the arch, and
invariably they are involved periodontally with
unfavorable crown-root ratios, the overdenture option
should be considered.www.indiandentalacademy.com

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The treatment planning include evaluation of all
potential abutments for:
• Periodontal status
• Endodontic status
• Caries management
• Positional considerations
• Economics

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PERIODONTALSTATUS:
It is best to select abutments that are in an
acceptable state of periodontal health but,
often it is necessary to use teeth that are less
than ideal. Abutment should have minimum
mobility, have adequate bone support and be
amenable to any indicated periodontal
treatment. Periodontal pockets, inflammation,
bony defects and poor zone of attached
gingiva must all be eliminated before
commencing the treatment.

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Extreme oral neglect
Periodontal probing

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Periodontal surgery
Splinting done

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A common periodontal requisite with overdenture
abutment teeth is that an adequate zone of
attached gingival is mandatory. This can be
accomplished with periodontal surgery utilizing
either a free gingival graft or apically repositioning
split thickness flap. This results in a band of
attached gingiva adjacent to abutment tooth. It
should be understood that reduction of clinical
crown-root ratio will be favorable in reducing any
existing mobility.

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ENDODONTIC CONSIDERATIONS:
There are mainly two advantages,
• The crown-root ratio can be made more favorable
• The reduction crown provides for an interocclusal
distance more favorable to placing the artificial
tooth in an esthetically acceptable position.

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CARIESMANAGEMENT:
The presence of high caries index and the
situation that will create a caries environment
are the devastating sequalae to improper
overdenture patient selection. An active caries
process can lead to a recurrence of in
unprotected abutment teeth or gingival to coping
margins and this can lead to failure of the
overdenture.

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POSITIONALCONSIDERATIONS:
1. Preference for anterior over posterior teeth
because alveolar ridge of anterior teeth appears to
be more vulnerable to reduction compared to
posterior alveolar ridge.
2. Two teeth in each quadrant presents an ideal
situation in where stress is distributed over a
rectangular area. Two canines and two second
premolars present an ideal situation. The tripod is
next most favorable form for support and stability.
The use of two teeth in each arch or one tooth in
one arch has met with satisfactory results. Morrow
recommends to use isolated teeth as abutments
because they return to healthy state readily and
are easier for the patient to maintain hygiene.

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3. The upper anterior teeth should be retained if
opposed by natural lower anterior teeth to
prevent the destruction of the anterior maxillary
ridge when utilized in a maxillary overdenture.
4. Mandibular cuspids are most often utilized since
they are usually last tooth to fall.
ECONOMICS:
Endodontic treatment, cast copings, attachments and
overdenture itself may workout expensive, so
economics of the patient should be considered.

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Types of overdentures
I. Overdentures for congenital and acquired defects:
Many patients with congenital and acquired defects
cannot be treated successfully with orthodontic or
surgical therapy, nor can they be treated with
conventional procedures – either fixed or removable.
However there has been a high degree of success in
treating these patients with complete dentures over
their existing teeth. The congenital defects most
frequently treated with over dentures are:
Cleft palate
Micordontia
Oligodontia
Cleidocranial dystosis
Class III patients with prognathic mandible.
The acquired defects most frequently treated by this
usually results from accidents, disease or misuse.

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Oligodontia

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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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Advantages:
1. Less expensive
2. Smooth transition
3. Minimal interference with function and appearance
Disadvantages
1.Border extension, esthetics, occlusion, support and
stability of the R.P.D. often are inadequate,
particularly after many years of use, making
satisfactory conversion difficult.
2.Weaker overdenture
3.Therefore, the converted prosthesis is considered as
interim or temporary overdenture, to be replaced
after a suitable transitional period.

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Conversion using patient’s teeth
The patient derives a tremendous psychological
boost by having his teeth removed, but leaving
with them still in his mouth; even through they are
in an overdentures. This is a more economical
method.
Pre op view

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Posterior teeth arranged and
tooth to be retained is
prepared
Resin teeth are hollow
ground

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Hollow ground Canines placed
Stone matrix formed

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Canines are reduced
Incisors are extracted

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1.Denture base ready 2. Stone matrix placed
3. Prepared teeth 4. Teeth joined

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Completed Transitional overdenture

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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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Impression tech no 1
Base plate wax adapted
Resin tray prepared

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Impression with rubber
base imp material
Alginate impression over
the rubber base

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Impression of edentulous area made in modeling plastic

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Impression is examined
Occlusal rims and
base plates

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Occlusal records made

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Casts secured on the articulator

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Replacement teeth are
positioned
Anterior teeth are
arranged

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Canine Prepared

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Resin tooth is hollow ground and placed

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Tooth indexing is done
Alginate impression of cast in flask

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Abutment height is measured on the cast and in the mouth
Tooth colored acrylic resin is sifted in the hollow
tooth

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Overdentures are ready

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Canines prepared and
remaining teeth extracted
Overdentures placed

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Disclosing wax is used
Interferences are reduced

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Tooth colored
autopolymerizing resin is
used for final seating of
the overdenture

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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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Removable partial overdenture fabricated on three
incisor teethwww.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):
The long coping is an excellent restoration,
applicable to many overlay techniques. It may be
used simply to provide stability and retention under
a telescopic overdenture.

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2. Medium Copings (4-6 millimeters for vital and
non-vital teeth):
Medium sized copings may be used with vital teeth
where the pulp has receded or with non vital teeth
having adequate bone support. Medium sized copings
are not generally designed as individual copings for
retention of the overlay prosthesis. They are generally
connected with some type of bar attachment. Or, they
may also be used with auxiliary plunger or pressure
button attachments. They are conical with greater taper
on all surfaces, particularly the facial surface when
used with bar attachments. If used with a plunger
button attachment, the surface engaged by the plunger
is flattened.

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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 nonvital
teeth):
Medium short copings are indicated for non-vital teeth;
where a more favorable crown root ratio is desired than that
possible with medium or long copings. This coping form
(and preparation) is indicated when: it is difficult to obtain
auxiliary retention of the coping on the abutment with a
dowel or parallel pins (the proximal walls of the preparation
should be very closely parallel for maximum frictional fit of
the coping); numerous neighboring abutments are to be
splinted, thus permitting better embrasure formation than
possible with very short copings; used with bar
attachments.

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4. Short Copings (1-2 millimeters for non-vital
teeth):
Short copings are fabricated to conform to the
curvature of the alveolar ridge, with a very low profile.
They are indicated for maximum favorable crown-
root ratio. Such short copings are particularly suited
to various types of stud attachments, but may also be
used effectively with many forms of bar attachments.

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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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ATTACHMENTS FOR OVERDENTURES
The ultimate objective of the prosthetic service is
to return the patient to as near a normal function
as possible. The basic overdenture concept is to
preserve the residual soft and hard tissues.
Mechanical stabilization can be improved by
incorporating the use of attachments and retentive
devices with the basic principles of complete
denture design.

99
BASIC PROSTHETIC DESIGN
It is important to realize that the causes of failure
inherent in the complete denture prosthesis are not
overcome by using attachment fixation. The use of
attachments does not authorize the abandonment of
basic principles. Failures of the hybrid prosthesis
(overdenture with attachment fixation) occur not
because of the attachments but because of
improper attachment selection and failure of the
dentist to develop maximum denture base
extension, atmospheric seal, and, for mandibular
bases, coverage of the retromolar pad.

100
Availability of the proprioceptive elements in the
attachment retained overdenture permits use of
gnathologic procedures and, in some instances,
anterior disclusion of the posterior teeth as well
as the relevant instrumentation desired. Use of
the attachment introduces another factor in basic
prosthetic design, that is, the demand for an
exact attachment prosthesis relationship. For
each type of attachment the demand differs,
depending on the availability or desirability of
resiliency and the overall adaptation of the
denture base over the soft and hard tissues of
the denture bearing area.

101
TOOTH PREPARATION
Tooth preparation varies with the type of support to be
provided. If there is sufficient tooth structure, that is,
3- to 8 mm of clinical crown for lateral stability of the
overdenture, there are several methods of preparation.

102
The coping is waxed to a minimal occlusal
thickness of 1 mm with the exception of the bulk of
the inlay seat.

103
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.

104
TELESCOPE OVERDENTURE:
The telescoped overdenture is an excellent alternative to
routine complete dentures. But what exactly is a telescoped
or coping overdenture? 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.

105
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

106
A Telescopic Overdenture Treatment Procedure:
Following is a case of advanced periodontal
disease and extensive breakdown of the natural
dentition. The teeth were devitalized and restored
with short and long copings to support an
overdenture in the following manner:
1. Examination, diagnosis and treatment plan.
2. Study casts for fabrication of interim
overdentures.
3. Prophylaxis, soft tissue curettage and home
care instructions.

107
Patient with extreme
dental neglect
Abutments are sectioned

108
Preliminary endodontic
therapy was carried out
Abutment tooth are roughly
prepared and hopeless
roots sectioned

109
Hopeless tooth and roots
removed
Periodontal surgeries
carried out, interim
dentures are very
important at this stage
worn for 3 months

110
Tissues have healed and
matured final preparation of
tooth is done now
After healing, the preparations were modified to
receive medium or long copings. Short copings
are to be placed on the two centrals. The other
abutment teeth were prepared to receive long or
medium copings. The overall preparation for the
longer copings was tapering with a rounded
occlusal or incisal.

111
A chamfer, or small shoulder with a beveled
marginal preparation, is prepared. This marginal
preparation is determined primarily by the type of
primary and secondary coping. If the secondary
coping was a crown rather than a hollowed denture
tooth, then the shoulder preparation must be more
substantial. The final preparation of the teeth should
result in a tapered cone shaped abutment rather
than a rounded occlusal or incisal. This preparation
should extend to the gingival sulcus as for a full
crown preparation. Sufficient tooth structure was
removed facially to make room for the coping and
set up of the anterior teeth, thus ensuring a more
esthetic result. The short anterior abutments were
prepared for dowel post retention.www.indiandentalacademy.com

112
Completed castings ready for
cementation. Long copings
for retention and stability and
short copings for support and
stability
Copings cemented
Now an impression was taken of the denture bearing
mucosa and copings to produce a master cast for
fabrication of the overdenture.

113
Master casts articulated
with accurate
interocclusal records
Coping undercuts are
blocked out with plaster

114
A metal framework with
a horseshoe like major
connector was fabricated
on a refractory model
Resin denture teeth
were hollow ground to fit
closely to the copings for
maximum esthetics

115
Completed overdenture
Secondary copings

116
A resin secondary coping of a telescoped
overdenture does have some advantages over a
metal secondary coping particularly where no
auxiliary retentive means are used. It is easier to
adjust the retention by adding autopolymerizing
resin to the previously relieved secondary
coping spaces and relining the coping spaces
directly in the mouth.

117
Relining and/or Rebasing
As the alveolar ridges resorb, the overdenture will begin
to rock and direct damaging lateral stresses to the
abutment teeth. Now the prosthesis must be adjusted for
a better fit by relining or rebasing. This is a simple
procedure and performed similar to any complete denture
relining or rebasing procedure:
1. Hollow out the secondary resin coping to provide
adequate room for the impression material; 2. Paint an
adhesive material on the denture base; 3. Load the tissue
area of the overdenture with an elastic impression
material; 4. Insert the overdenture in position and have
the patient close gently into occlusion as you muscle trim;
5. Now the overdenture is relined or rebased similar to
any complete denture technique and ready for use.

118
ATTACHMENTS:
Bar compared to stud fixation
The splinting of two or more teeth with a bar
produces stability similar to the rigid stud type
attachment when the overdenture is in place. The
question that arises immediately is: if the denture
base is so well developed that the bar serves only
as a fixation device, what is the difference in the
result of splinting obtained in the stud prosthesis
and in the bar prosthesis. Theoretically, there is no
difference, but the stud type allows independent
movement, and, if one tooth is especially weak, the
strong tooth can serve as the fulcrum point for
movement of the weaker tooth in the prosthesis.www.indiandentalacademy.com

119
With bar units and joints, many times the bar
splints in more than one plane. Instead of the
prosthesis moving one tooth, all or none move
under a functional load. With bar fixation, a
stronger and a weaker tooth can be splinted with
the result that the stronger tooth strengthens the
weaker tooth and the weaker tooth weakens the
stronger tooth. In making the overdenture; only the
stud, the bar, and some of the accessory
attachments are of interest.

120
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

121
Accessory
5. Auxiliary attachments
a. Screw units
b. Pawl connectors
c. Bolts
d. Stabilizers/balancers
e. Interlocks
f. Pins/screws
g. Rests

122
The various attachment systems have been organized in a
compendium known as the EM attachment selector, which
presents thirty points of information about each attachment
(Mensor, 1973). This selector and the EM gauge (Matsuo,
1970) provide a simple color code method of choosing
attachments from the mounted diagnostic casts.

123
STUD(PRESSURE BUTTON) ATTACHMENTS:
Most of the stud-type attachments can be considered
to be "snap fasteners" and are the simplest in
concept. They can be resilient or non resilient.

124
RESILIENT STUDS
Resilient attachment systems are selected to perform
a compensatory service and to act as a safety valve
for any overload situation. No two resilient attachment
systems should oppose each other unless the
attachments in the maxillary prosthesis are locked out
of function, for the maxillary prosthesis receives
additional support from the palatal coverage. This
situation arises when two hybrid prostheses oppose
each other or a mandibular appliance opposes the
maxillary denture.

125
When the mandibular appliance opposes a natural
dentition, some provision should be made for
movement so that maximal tissue contact of the
denture base can be achieved under maximal load.
In the well developed denture base with careful
positioning of the attachments, the need for a
resilient system becomes questionable. No attempt
should be made at equilibrating or establishing
permanent records or relining procedures without
locking the resilient attachments out of function,
because the base would move and produce
incorrect markings of the interferences.

126
The retained root with an attachment offers
retention and positional or directional orientation
for the appliance. When there is either inadequate
technique or inability to develop a well fitting
denture base, the resilient attachment gives some
leeway to acceptance of the prosthesis by allowing
more base contact and support during function.
NONRESILIENT STUDS
The nonresilient stud attachments are used when
interocclusal space is limited. They should be used
when the teeth are stable or when the dentist does
not desire movement or potential movement of the
overdenture.www.indiandentalacademy.com

127
When to Use a Resilient Stud?
A resilient attachment permits the tissue to compress
slightly before any load is transmitted to the
abutment. It is usually preferred:
When there are only a few abutments.
When abutments have minimal bone support.
For tissue tooth supported prosthesis.
When functioning opposite natural dentition.
When functioning against a nonresilient appliance (do
not use opposite another resilient appliance).
When multi-directional (stress-broken) action is
desirable.
When there is a minimum denture base.

128
When to use a non Resilient stud Attachment ?
A non resilient attachment will not allow vertical
movement (however it may permit rotational
movement)
When no vertical movement is indicated.
When an all-tooth supported prosthesis is
desired.
When a tooth-tissue supported appliance is
desired.
With strong abutments having maximum bone
support (one-half or more).
When functioning against a resilient prosthesis
When a large, well-fitting denture base is possible.
When there is little interocclusal space
Opposite a complete denture.www.indiandentalacademy.com

129
Some Stud Attachments:
1. Dalla Bona
2. Intrafix
3. Ancrofix
4. Gerber
5. Gmur
6. Rotherman
7. Huser
8. Schubiger
9. Ceka

130
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

131
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.

132
Convenient tools are also
used in the fabrication -
female screwdriver, male
screwdriver, paralleling
mandrel, heating bar, and a
soldering cornal

133
Step-by-Step Technique:
1. All treatments must start with a thorough oral
examination. This examination should include
patient history, visual examination, radiographs
and periodontal probe evaluation. Accurate study
casts mounted on an appropriate articulator are
also helpful.
2. A thorough oral prophylaxis and home care
instructions are completed before any other
treatment is performed.
3. Fabricate an interim overdenture on the diagnostic
casts for insertion after reduction of the clinical
crowns, endodontics, extractions and periodontal
surgery.

134
4. All the teeth are reduced to
one to two mm above the
gingiva
5. Endodontics is performed
6. Partial preparation of the teeth
7. Extraction of hopeless dentition
8. Hollow out recesses in the interim overdenture
9. Now that the teeth have been initially reduced, the
hopeless dentition removed, and the interim
overdenture ready for insertion, periodontal therapy can
be completed in a relaxed manner with relative patient
comfort.

135
10.Insert the interim overdenture with a soft relining material
11.After several weeks of healing, complete endodontics (if
not completed).
12.After tissue healing
and maturation (2-3
months) complete
abutment preparations
for short copings with
post retention.

136
13.Master cast with
removable dies
14.Copings waxed on
individual dies shaped
to conform to the
alveolar ridges. Resin
dowels were used as
dowel patterns

137
15.Position the finished
castings on the cast (lock
them together with Duralay);
invest and solder them to
form a splinted substructure
16.Preliminary intraocclusal
relation records for a trial
set-up of denture teeth. The
anterior teeth are oriented
with a plaster core. This
helps to accurately position
the male attachment on the
copings www.indiandentalacademy.com

138
17.Position the male attachment on the coping. Consider
the following factors when determining the position of the
male posts:
- Is there sufficient vertical space?
- Place the posts over abutments with the
most bone support.
- Position the males slightly lingual. This provides
more room for the anterior denture teeth.
- Utilize abutments in different planes for maximum
retention, stability and support .
- The attachments must be parallel to each other and
to the path of insertion of the overdenture

139
18.Lock the cast on the
surveying table. Loosen the
male sleeves and Place in
the paralleling mandrel.
Find the most
advantageous position for
the posts. Tilt the surveying
table so that the studs will
be aligned to the path of
insertion of the prosthesis.
19.Sticky-wax the male base
to the coping

140
20. Male sleeve is being
removed
21. Male stud sticky
waxed to the coping
with sleeve removed

141
22.Screw the soldering cornal
onto the threaded base. It
acts as an extension arm
for the screw to aid in
soldering
23.Cover half of the
soldering cornal and
coping with soldering
investment.

142
24. Finished copings with
attachments assembled and
soldered, positioned on the
abutments
25.Take an accurate muscle
trimmed master
impression "pulling" the
coping substructure, on
the abutments, to form
the master cast for the
overdenture fabrication

143
26. 3-4 thickness of x - ray
foils are adapted to all
copings for spacing.
27. Block out all undercuts
around the foil spacer
and copings with plaster

144
28.Place a small amount
of Vaseline inside
each female then
snap it (with its
copper shim) onto the
male
29.Paint a thick mix of auto-
polymerizing resin at the
male-female joint. This will
prevent processed denture
acrylic resin from being
forced into the attachment
during denture packing
procedures

145
30.Design the framework
with a major connector for
support and a minor
connector for the acrylic
denture base. Fabricate
and finish
31.Take accurate
occlusal records and
mount the casts on an
appropriate articulator
for the denture setup
and denture is
fabricated

146
32.Females locked inside. All
excess plaster and resin is
removed. Use the female
screwdriver to disassemble
the female, remove the
copper shim and
reassemble. This activates
the attachment making it
resilient.
32.The overdenture is ready for
insertion

147
Cement the copings onto the roots and insert
the overdenture

148
Non-Resilient Gerber
The non-resilient Gerber attachment technique is
similar to that described above but with one
exception. As it is non-resilient, the overdenture
and female rest on the tissues, copings and
male posts in a passive position; no spacing is
necessary. Therefore, do not place spacers over
the copings. (Of course, the non-resilient Gerber
has no copper shim spacer.)

149
Maintenance Consideration
Relining or Rebasing
Alveolar resorption will eventually cause the
denture to rock about the abutments. This rocking
will increase the rate of resorption; abutment
bone support will be continually lost. Such
destructive action may even cause dislodgement
of the copings, breakage of attachments, or even
the splitting of the abutment. The appliances
should be relined or rebased to eliminate these
stressful forces.

150
Remove the internal
parts of the female with the
female screwdriver.
Carefully set aside all
internal parts to be
reassembled later.
Screw the relining
heating tool into the female.
Heat the end of the bar in a
Bunsen burner flame. The
heat transfer will soften the
acrylic around the female,
making it easy to remove
Procedure for relining

151
Grind out several
millimeters of the acrylic
resin within the female
recess. Place the female
attachments (with their
copper shims in place) over
the posts in the mouth.
Place an adhesive on the
tissue side of the overdenture, fill
the prosthesis with an elastic
impression material and take the
impression using a routine
complete denture relining
impression technique. Have the
patient close into occlusion while
the impression material sets.www.indiandentalacademy.com

152
Male relining jig
Insert the special
male relining jigs
(transfer males) into
the females until a
definite snap is felt

153
The set cast, with the overdenture, is
articulated to a special relining jig. The
relining or rebasing procedure is similar
to a conventional denture relining or
rebasing technique. Separate the
articulator and remove the cast from the
overdenture impression. The cast has
the transfer males in the same location
as in the mouth
The cast and attachment management
is handled like the initial fabrication
technique: the spacers are placed over
the stone copings; females (with their
copper shims) are placed on the males;
all undercuts are blocked out with
plaster; the denture teeth are
repositioned on the cast via the relining
jig, and the overdenture is fabricated by
any conventional denture procedurewww.indiandentalacademy.com

154
Advantages of the Gerber attachment
1. It provides adequate retention, stability and
support.
2. Its retention is light and easily adjustable with
springs adjustable and readily replaced.
3. All of its post sleeves are interchangeable and
replaceable, with the exception of the male screw
base.
4. It can be used in conjunction with bars.
5. It can be processed directly into the overdenture
or positioned in the mouth with autopolymerizing
resin. www.indiandentalacademy.com

155
Disadvantages of Gerber attachment
1. It is a complex attachment and maintenance
problems are relatively common. The male sleeve
may become loose. The internal parts of the female
may dislodge when the retaining screw unthreads.
2. Its large vertical dimension makes it impractical
for minimal interocclusal space.
3. It requires an assortment of tools for fabrication
and maintenance.
4. The attachments must be parallel.
5. The Gerber permits very little rotational action, so
torquing of abutment teeth will occur with alveolar
resorption. www.indiandentalacademy.com

156
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.

157
Dalla bona attachments on
two cuspids makes it
excellent overdenture
arrangement
Spherical Bona with
undercut for retention

158
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

159
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.

160
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.

161
Advantages
1. Their overall length varies between 3.3 millimeters
(cylindrical), to 3.7 millimeters (spherical), so it is
suitable for short interocclusal spaces.
2. It provides firm, definite retention.
3. It can be processed into the overdenture in the
laboratory or mounted in the mouth using
autopolymerizing resin.
4. It is less expensive than the Gerber.
5. Parallelism of the spherical Bona is less critical
than that of the cylindrical Bona.

162
Disadvantages
1. The retentive action of the female is very stiff and
difficult to adjust.
2. The collar that retains the female housing in the
prosthesis is too small. Therefore the female may
become loose with normal adjustments and use.
3. The males must be parallel, particularly in the
cylindrical form.
4. There may be some torquing and tipping of the
abutment.

163
Spherical Dalla Bona Treatment
Diagnosis, treatment and management using the
Dalla Bona are very similar to that described for the
Gerber.
Step by step procedure
1. The various clinical steps depend on the existing
conditions. They would normally include
examination, diagnosis, home care, initial
preparation, endodontics, extractions, periodontics,
interim overdentures, final preparations and casts
with removable dies for coping fabrication.

164
Casts with the removable
dies are fitted with the
resin dowel pattern
coping pattern is waxed

165
To improve the soldering
procedure, cut a ditch in the
diaphragm of the coping.
This ditch aids the flow of
solder under the stud base
With the cast on a surveying
table, use a paralleling
mandrel to position the male
studs parallel to each other.
Located slightly lingual. Now
sticky wax them into
position.

166
Add a short strip of round
wax to one side of the
waxed base. This will
produce flame vent holes
within the investment
material. This also aids the
soldering procedure
Preheat in an oven to 1400
degrees F. Flame solder
the male to the coping by
adding solder in the
prepared ditch. The copings
with their soldered
attachments are now
polished and ready for
assembly.

167
The coping substructure
is withdrawn from the
abutments with an
accurate muscle trimmed
impression to become
integral part of the master
cast
The female snapped on to
the stud. The Teflon ring is
positioned firmly on the
base

168
Block out all coping
undercuts with plaster
The casts are articulated on
an appropriate articulator with
accurate occlusal records
for set up of the denture teeth.
The overdenture, with an all-
metal base is processed and
finished for insertion with the
female retained inside the
denture base

169
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.

170
The Rotherman anchorage
has a short solid stud( non
resilient right, resilient left)
and a double armed clasp.
The clasp has bar for
retention within the denture
base
Non resilient left and
resilient right with aluminum
spacer

171
The male features a definite undercut on just one
side of the cylinder. A scribe line on the occlusal
indicates the position of maximum undercut. The
male must be soldered to the coping so that this line
(and the undercut below it) is positioned facially. This
way, the female's clasp arms will reach around from
lingual to engage the undercut and the bar like
retentive lug will fall in the lingual portion of the
denture. There it will not interfere with the tooth setup
and will be locked in thicker resin.
The Rotherman is the easiest of all attachments to
solder, for it comes with solder built into the center of
the male. The technician need only position the male
on the coping and then hold it in a flame until the
solder flows.www.indiandentalacademy.com

172
Ancrofix Attachment
The Ancrofix is similar to the spherical Dalla Bona
with a rounded male post providing the undercut for
retention. Of course, the female is processed within
the overdenture. This attachment consists of a male
base which is soldered to the coping diaphragm, a
removable sleeve knob that provides the undercut;
the female has adjustable lamellae that engage the
male undercut for retention. A Teflon ring covers the
female lamellae similar to the Dalla Bona. This
attachment is 3.2 millimeters in height and can be
used in most instances a rotational action is
desirable. It can be made resilient by removing the
small knob located on top of the male stud and by
spacing the copings.www.indiandentalacademy.com

173
Ancrofix stud
Male stud and female
with Teflon sleeve

174
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.

175
Types of BarAttachments
Bar units
Bar joints

176
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.

177
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.

178
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.

179
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.

180
Typical Dolder bar Treatment:
• Endodontics, extractions and periodontal surgery
were completed prior to starting the operative
process. Tooth preparations were started only after
healing.
Reduce the
endodontically treated
cuspids to one to two
millimeters above the
gingiva.

181
Diamond bur is used to
prepare the abutments with
a bevel or chamfer margin. X
indentation is made.
The copings can be retained with posts, parallel or non-
parallel pins, or a combination of both. As the two cuspids
will be splinted with the bar joint, the posts (used in this
case) must be parallel to each other. The para-post
system was used to prepare these parallel "sized" holes to
receive the impression posts. Enlarge the canal opening
with a number six or eight bur to one half of the bur head
depth. This adds strength to the dowel casting union here.

182
Fabricate a customized
impression tray on the
study cast. Prepare holes
in the tray over the root
preparations. The
impression posts will
pass through these
holes.
Take a muscle trimmed
impression of the teeth
and soft tissue areas.
The previously positioned
impression posts are
withdrawn with the
impression

183
Plastic dowels used as
dowel patterns
Short coping patterns
are waxed to conform
to curvature of the
alveolar ridge

184
The copings are finished, but
are left with a short section of
the sprue on each casting
which will be removed later.
These retained sprue posts
aid in the assembly of the bar
to the copings for soldering
Set up the denture teeth and
check with the patient for
occlusal harmony, vertical
dimension and esthetics

185
Cut the bar to fit between
the copings. The bar
should be positioned
slightly lingual
Connect the bar to the
copings (the short sprue
stubs help here) with
Duralay, or sticky wax.
Invest and solder to the
copings. www.indiandentalacademy.com

186
Retentive shell is cut
and fit over the bar
Shell is modified for better
retention
Method of modification

187
The metal spacer is
positioned over the bar and
the retentive shell is
snapped on the bar
securing the spacer.
Space must also
be provided over
the copings.

188
Block out all undercuts
around the copings with
plaster and cover the
flanges of the retentive
shell
Consequence of
excessive block out

189
With a small brush,
sparingly paint a semidry
mix of auto polymerizing
acrylic resin (such as
Duralay) to cover the end
of the spacer and shell
Framework is constructed
and secured on the cast

190
Use the stone index to
reposition the anterior
teeth and complete the
denture set-up
The denture is waxed,
festooned, flasked,
processed and finished.
The coping bar assembly
is removed but the
retentive shell is retained
within the tissue side of the
denture www.indiandentalacademy.com

191
Cement the
Dolder
bar/coping
assembly into
position. The
overlay denture
is inserted for
use.

192
Overdenture Function
Let us now consider the function of this
overdenture. Freedom for vertical movement,
provided by the auxiliary wire spacer and lead foil
covering the copings during fabrication, allows
approximately 0.5 to 1.0 millimeter of space for
movement during function

193
At rest, the overdenture sits
passively only on the
alveolar tissues. A space is
present between the bar-
coping assembly and the
shell tissue side of the
overdenture. There is
maximum retention now
since the clip engages the
bar undercut
During mastication, the
denture moves vertically.
Now it is supported by both
the alveolar tissues and the
root supported coping bar
substructure.

194
Adjusting Retention:
Retention of the overdenture is easily increased or
decreased by adjusting the flanges of the shell to
provide desirable retention.
Relining/Rebasing Technique
As the alveolar ridge resorbs, the overdenture
settles and rocks on the Dolder bar assembly.
These excessive masticatory loads direct
damaging torquing stresses to the abutments.
When this occurs, the following rebasing procedure
should be followed.

195
1. With a small round bur, carefully remove the acrylic around the
shell, and remove the shell. It will be used later.
2. Remove additional acrylic above the area of the copings and bar
using a straight handpiece with a number eight
bur. This additional space will accommodate the impression material.
3. Dry the denture and paint the tissue areas with an impression
adhesive.
4. Using the elastic impression material of your choice, take an
impression of the tissue bearing areas, copings and Dolder bar. The
patient should close gently into occlusion, as you muscle trim the
impression material. When a large space is present under the bar or
between the copings, it should be blocked out with soft wax or cement
prior to taking the impression. Otherwise, tearing away of the
impression material from these voids, when the impression is
removed, will distort and destroy the accuracy of fit when the
prosthesis is rebased.

196
5. The impression is
poured with model stone.
6. The cast with the
overdenture attached is
mounted in a relining jig.
The teeth are indexed in
the opposing member
and the jig is opened
after the plaster has set.

197
7.The overdenture is
removed from the cast
leaving a reproduction of
the soft tissue, the copings
and Dolder bar.
8. The denture teeth are
removed from the
overdenture and are
positioned in their
appropriate slot in the
plaster index.

198
9. The cast is now treated as if you are fabricating a new
overdenture i. e,
• Place three to four layers of X-ray foil over each
coping as a spacer.
• Place the metal spacer over the mold of the bar.
• Snap the retentive shell into position over the spacer
and plaster bar.
• Using plaster, block out the retentive flanges of the
shell and all undercuts.
• Block the ends of the shell and spacer with resin.
• Reposition the cast on the relining jig; wax the teeth
into position; wax the denture base; festoon, flask,
pack, cure and finish the overdenture as in any
complete denture technique.
• The rebased overdenture is now ready for insertion.www.indiandentalacademy.com

199
The Dolder Bar Unit
The Dolder bar unit is an excellent attachment
when an all tooth supported, non rotational
acting overdenture is desired. This bar design
may be indicated if there are numerous
abutments - especially if they are located in
three planes; i.e. posterior and anterior
abutments.

200
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.

201
Components of the Hader system are (from left to
right).
• Plastic bar pattern (1.8 mm diameter, vertical height
5.7 mm).
• Plastic clips (5 mm long, 3 mm thick, 4 mm high).
• Modeling riders used in processing to create a slot
for the clips.
• Clip seating tool.

202
Hader Bar Technique
• Take an impression of the prepared abutments,
pour a cast and trim the dies as you would any
bar retained overdenture.
• Wax the coping pattern on the dies.
• Cut the bar pattern to fit between the coping
patterns.
• Heat the bar pattern and adapt it to the ridge
curvature.
• Trim the gingival portion of the bar pattern to fit
the alveolar ridge.
• Wax the plastic pattern directly to the coping
patterns for a single casting, or for greater
accuracy, cast separately and solder to the
copings www.indiandentalacademy.com

203
7.The completed
substructure pattern
is sprued, invested,
cast and finished.
8.Seat the
substructure on
the cast for
completion of the
overdenture

204
9. Position modeling
riders on the bar where
clips will attach. These
riders are removed
after the prosthesis is
fabricated, leaving a
preformed seat to
receive the plastic clips
for retention.
10.Using plaster, block
out all undercuts
around copings and
below the round
portion of the bar

205
11.When the overdenture
is finished, remove the
modeling riders with
pliers or a sharp
instrument
12. Use the special
seating tool to
insert the plastic
clip into the slots
formed by the
modeling rider

206
13.The denture is now
ready for use
Metal clips for retention
If a metal rider is
preferred, it should be
incorporated into the
prosthesis when it is
initially fabricated.
Instead of using the
modeling rider,
substitute the metal riderwww.indiandentalacademy.com

207
Advantages of the Hader System
1. The plastic bar pattern is easily adapted to differences in
the surface of the gingival ridge and gingival curvature.
2. The plastic bar pattern simplifies the laboratory technique
by eliminating a soldering step.
3. Plastic riders give adequate retention and are easily
replaced.
4. Its rotational joint action relieves stresses from the
abutment teeth.
The main disadvantage of this system is its plastic rider which
cannot be altered for additional retention. However, the
adjustable metal riders can be used to eliminate this problem.
In addition, there is no provision for developing vertical
function with the overdenture. Commercial retentive clips can
be used with these customized bars.www.indiandentalacademy.com

208
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.

209
SCREWS:
Schubiger Screw Attachment
An excellent screw attachment often used in
overdenture technique is the Schubiger. This
attachment is a very versatile screw-type
system, used with Gerber and bar combinations.

210
Plunger-Type Attachments
Auxiliary retention for an overlay prosthesis is
often desirable and it may be added to various
coping or bar systems. Plunger type units such
as the Ipsoclip, Presso-matic and IC
attachments can add additional retention

211
Review of literature
Paul A. Miller ( 1958) gave special
emphasis on preservation of tissues with
support of artificial teeth. The use of
teeth as support for dentures is aimed at
reducing the load on the osseous
portions of the denture bearing area and
minimize the process of resorption.

212
Dolder E. J. in 1961 advocated the bar joint
denture. The denture is adapted primarily to the
situation with which only a few teeth remain. The
basic construction procedures consist of
(1) Shortening and capping the residual teeth to
render the crown: root length ratio more
favorable and
(2) Splinting the abutments with a straight bar
affixed to the cemented copings which serves, at
the same time, as the bearing shaft for the
complete denture.

213
Robert J. Crum and R. J. Loiselle
(1972) in his review of literature reveal that
discrete sensitivity that exists in the separate
components of masticatory system. It also
demonstrates the necessity for total integration
of each component of the masticatory system
and signals the importance of preserving the
natural teeth.

214
Merrill C. Mensor (1973) advocated the use of
E M attachment selector which consists of 8.5
by 11 inch color coded selector cards. It is
compendium of attachments and connecting
units available through out the world and it
contains 30 points of information for each of
more than 105 different attachment systems,
this is a total of over 3000 points of information.
Each of the cards numbered to correspond with
5 attachment classifications.

215
Joseph T. Quinlivan (1974) said that retention is
a problem for overlay dentures over simple
copings when only two teeth remain. This is
particularly a problem when treating a
mandibular arch, which has a more limited
basal seat area. He advocated RCT of the
abutment teeth; pulp space to be enlarged with
a Gates Glidden drill and finally with a safe
sided para post drill. Then he advocated used
ball and socket type of attachment for
overdenture on the teeth reduced I mm above
the gingiva.

216
Wayne R. frantz (1975) described the
construction of tooth supported dentures where
the natural tooth was utilized and the acrylic
resin for denture base processed directly to the
prepared cast. He said that abutment teeth with
their coping may result in 3-5 mm above the
gingiva which causes undue stress and torque
on the teeth. He advocated natural teeth to be
reduced 1-2 mm above gingiva fill the pulp
chamber with amalgam and give a very high
polish and construct the denture.

217
A. B. Warren and A. A. caputo (1975)
conducted a study to determine and compare
the transfer of forces to the alveolar bone for
five different abutment designs for the tooth
supported dentures and concluded that there
was a direct relationship between the stability
and retention that each design provided and
the amount of stress and torque transferred
to the supporting structures. Attachments that
used parallelism or undercuts for retention
tend to produce the most severe stress
conditions in the supporting alveolus.

218
H H Thayer and A A Caputo (1977) provided the
following guidelines in the selection of specific
designs for overdenture abutments:
1.The Dolder bar, which exhibits more cross-arch
involvement than the Zest anchor, will share the
occlusal load across the arch, between the
abutments and the supporting structures.
2.The posterior edentulous regions will receive some
physiologic stimulation with the Dolder bar, for it
shares more stress here than the Zest anchor.

219
3. The forces on the Dolder bar produce stress
directed more apically than that from the Zest
anchor. Since this force is better tolerated, use
of the Dolder bar may be indicated for a short-
rooted tooth with less supporting bone.
4. The greater stress concentrated around the
abutment teeth by the Zest anchor makes use of
this design in a tooth that is periodontally sound
and has a long root structure well imbedded in
supporting bone seem logical.

220
Merrill C. Mensor (1978) said that when selecting
an attachment it is essential to consider the skill of
the dentist – laboratory teem as well as dexterity of
the patient and to use the easier system that will
still improve stabilization. He advocated the use of
E M gauge and E M attachment selector to reduce
confusion in selection attachments.

221
Robert J. Crum and George E. Rooney (1978)
conducted a 5 year clinical study to determine
the amount of bone loss in the anterior part of
the maxillae and the mandible in two groups of
patients: one group with complete maxillary
dentures and mandibular overdentures and
other group with complete maxillary and
mandibular dentures. The result show that group
–I demonstrated less alveolar bone reduction
than group –II.

222
H. H. Thayer and A. A. Caputo (1979)
concluded that
a) The more retentive tissue bar and extra
coronal attachments produces higher stress
concentrations
b) The Hader bar produced less torquing forces
c) The Ancrofix appeared to share the forces of
occlusion between the abutments and the
posterior edentulous regions.

223
Gary D.Derkson and Michael Macentee ( 1982)
conducted a study to observe the therapeutic
effect of 0.4% stannous fluoride gel on the
periodontium and the tooth structure of
overdenture abutments and they found that
0.4% stannous fluoride gel is an effective agent
in reducing the progress of gingivitis around
overdenture abutments.

224
Conclusion:
To conclude it would not be a repetition to say
that overdenture is a preventive dentistry
concept which has been brought into
Prosthodontics. The alveolar bone and its
overlying mucosa was never intended to
receive the full force of the complete denture.
Even though the technique resembles those of
complete dentures, there are important
differences. The prognosis of the restoration is
likely to be influenced by numerous factors
like:

225
1) Selection of patient
2) Treatment planning
3) Preparation of the mouth
4) Execution of the prosthodontic work
5) Maintenance
Finally it is reasonable to conclude that
retention of the part of the natural dentition
affords the overdenture patient a gain in
neuromuscular performance thereby having
an edge over his edentulous counterpart.

226
References
1. Brewer AA, Morrow RM: Overdentures, ed 2. St
Louis, CV Mosby, 1980.
2. Crum RJ, Rooney GE Jr: Alveolar bone loss in
overdentures: A 5-year study. J Prosthet Dent
1978;40:610-613.
3. DerksonGD, MacEntee MM: Effect of 0.4% stannous
fluoride gel on the gingival health of overdenture
abutments. J Prosthet Dent 1982; 48:23-26.
4. Ettinger RL, Taylor TD, Scandrett FR: Treat-ment
needs of overdenture patients in a longitu-dinal study:
Five-year results. J Prosthet Dent 1984;52:532-537.
5. Mensor MC Jr: Attachment fixation of the overdenture:
Part II. J Prosthet Dent 1978;39:16-20.

227
6. Quinlivan JT: An attachment for overlay dentures. J
Prosthet Dent 1974;32:256-261.
7. Thayer HH, Caputo AA: Occlusal force transmis-sion by
overdenture attachments. J Prosthet Dent 1979;41:266-
271.
8. Thayer HH, Caputo AA: Effects of overdentures upon the
remaining oral structures. J Prosthet Dent 1977;37:374-
381.
9. Winkler .S . Essentials of complete denture
Prosthodontics, second edition,2000, 384-402.
10.Paul A. Millar: complete denture supported by natural
teeth. J Prosthet Dent 1958;8:924.
11.Dolder E. J: The bar joint mandibular dentures. J
Prosthet Dent 1961;11:689.

228
12.Wayne R Frantz: The use of natural teeth in
overdentures. J Prosthet Dent 1975;34:135-140.
13.A B Warren and Caputo: Load transfer to alveolar bone
as influenced by abutment designs for tooth supported
dentures. J Prosthet Dent 1975;33:137.

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