Edentulous Mandible - Overlay Dentures

11. Edentulous Mandible
Overlay Dentures

John Beumer III DDS, MS
Hiroaki Okabe CDT
Division of Advanced Prosthodontics, Biomaterials and Hospital
Dentistry, UCLA
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Table of Contents
v  Conventional dentures vs implant retained dentures.
v  Which patients benefit from implant retention
v  Patient satisfaction: Conventional dentures vs implant retained dentures
v  Treatment choices
v  Clinical outcomes studies
v  Fixed vs removable
v  Issues of concern
v  Tissue bar designs
v  Hader
v  Hader – ERA
v  “O” Rings and similar type attachments
v  Advantages vs disadvantages
v  Prosthodontic procedures
v  Hader bars Prosthodontic procedures
v  Impressions
v  Maxillo-mandibular records and try in
v  Tissue bar design and fabrication
v  Delivery sequence
v  Implant supported tissue bars
v  The 4 implant assisted tissue bar

Problems with mandibular dentures
v  Lack of stability, lack of retention, poor support and poor
neuromuscular control make it difficult for many patients to
efficiently manipulate the food bolus along with the lower
denture sufficiently well to masticate at levels consistent with
their expectations.

v Implants can overcome these problems in many patients
v However implants may not be necessary and may not improve
the overall level of function if the patients present with favorable
mandibular denture bearing surfaces.

Edentulous Mandible-Overlay Dentures
Conventional dentures vs implant retained
overlay dentures.
v  Which patients will most likely be capable of
functioning effectively with conventional
dentures?
v  Which patients stand to benefit from implant
retention?
v  Does the addition of implants improve the
mastication efficiency of patients using
complete upper and lower dentures?

Characteristics of favorable denture bearing surfaces
Floor of Mouth Posture and Tongue Position

v Floor of mouth posture and tongue position (depth of retromylohyoid space) affect
stability and retention
v Broad – rounded alveolus covered with attached keratinized mucosa enhance support
v Patients with favorable floor of mouth contours and anterior tongue position as seen
above permits development of a longer lingual flange.
v Result: Improved stability and retention of the mandibular denture
v Such patients have a good prognosis for effective use of conventional dentures

Characteristics of favorable denture bearing surfaces

v  Patients presenting with a favorable floor of mouth contour, and anterior tongue
position and a reasonable zone of attached keratinized mucosa available to
engage for support as seen in these patients are excellent candidates for
conventional complete dentures.
v  In such patients significant lingual flange extensions can be developed facilitating
stability and retention. With coverage of the retromolar pad, proper extensions
onto the buccal shelf and good adaptation with attached keratinized mucosa of the
alveolus, sufficient support will be provided.
v  Implant retention will most probably not enhance the functionality of such patients
as compared to conventional complete dentures.

Characteristics of unfavorable denture bearing surfaces
Patients with unfavorable floor of mouth posture and tongue position (a, b).
The tip of the tongue has lost its definition and is retruded and the floor of
mouth is elevated.

a b

Result:
v Length of the lingual flange of the denture will be limited, compromising
stability, retention and the ability of the patient to control the lower
denture and compromising the prognosis for conventional complete
dentures.
v Such patients will benefit the most from implant retained overlay dentures.

Which patients benefit from implant retention?
Patients with unfavorable floor of mouth contours and
retruded tongue position

v  In such patients retention and stability is provided by the
implants.
v  Support anteriorly is provided by the implants
v  Support posteriorly is provided by engagement of the
retromolar pad and buccal shelf (dotted line)

v This patient presented with a retruded tongue position, unfavorable floor of
mouth contours but a wide zone of keratinized attached mucosa on the
alveolus. Support is excellent but stability and retention will not be ideal
because the length of the lingual flange will be relatively short.

v Such patients will probably derive functional benefit from implant retention.
v The implant will enhance support but the primary benefit is improved stability and
retention,
v In addition maintenance of healthy peri-implant soft tissues will be relatively easy
because of the wide zone of keratinized attached mucosa.

Unfavorable floor of mouth contours lacking keratinized
attached mucosa
Patient (a) presented with retruded tongue position, unfavorable floor of mouth contours
and a very narrow zone of keratinized attached mucosa on the alveolus.

a b

Such patients would stand to gain significant functional improvement with the
addition of implants to retain and stabilize the lower denture. However with so little
attached keratinized tissue remaining, widening the zone of keratinized attached
tissue with a palatal graft should be considered in such patients (b).

Neuromuscular Control
Some patients have the ability to manipulate their lower
denture and control the food bolus simultaneously, regardless
of the quality of the design and construction of the denture or
the quality of the denture bearing surfaces.

The opposite is also true and those with poor neuromuscular
control will benefit from implant retention. Such patients can
focus their attention exclusively on manipulation of the food
bolus since the denture is effectively retained and positioned
with the implants.

Conventional Dentures: Pt. Satisfaction
Most patients are satisfied with their dentures in spite
of the difficulties referred to in the previous slides.

Dissatisfied
7.7 %

Moderately
Satisfied Fully Satisfied
25.6 % 66.7 %

Berg E (1998); Smedley TC et al
(1989); Kapur KK et al (1997)

Expectations met = Pt. satisfaction

Conventional Dentures: Masticatory Performance
Effect of Improvements in Fit or New Dentures
v  Improvements in chewing function were perceived by
most pts. despite the lack of improvement in masticatory
performance. Denture wearers may perceive chewing ability
in terms of chewing comfort rather than the ability to
comminute food, an objective measure of chewing
performance.
Garrett et al. 1996

v  Results indicate that dentists cannot rely on asking denture
wearers about chewing problems and clinical responses with
respect to oral conditions and denture quality for predicting
patient’s , masticatory abilities. Masticatory ability is
determined by many factors.
Slagter et al. 1992

Conventional Dentures: Pt. Satisfaction
" Outcome from the pt’s point of view is only in part related to
technical aspects of the treatment modality
Vervoorn 1988, Van Waas 1990

" The technical denture quality accounts for less than half of
the total success
Miller, 1960; Devan, 1963

" Denture satisfaction is influenced by various factors,
including denture quality, the denture bearing area available,
the quality of dentist-patient interaction, previous denture
experience and the patient’s personality & psychologic well
being. Berg, 1991

Treatment choices
Implant Supported Implant Assisted Fixed Edentulous Bridge

Evidence Based Dentistry

v  Are
mandibular dentures retained with dental implants
the ‘best‘ treatment for the edentulous patient (better
than conventional dentures)?

v  Functional
(objective) and perceptual (subjective)
outcomes of treatments
v  Conventional dentures
v  Implant assisted overlay dentures
v  Implant supported overlay dentures
v  Fixed implant supported prostheses

A Randomized Clinical Trial Comparing
Implant Overdentures and Conventional
Dentures in Diabetic Patients

Investigators
Krishan Kapur, D.M.D.(PI) Neal Garrett, PhD(Co-PI)
Eleni Roumanas, D.D.S. Michael Hamada, D.D.S.
Earl Freymiller, M.D., D.D.S. Tom Han, D.D.S.
Weng Kee Wong, Ph.D. Seymour Levin, M.D.
Randy Diener, D.D.S. Tenglang Chen, D.D.S.
John Beumer, D.D.S

UCLA School of Dentistry and West LA VA Medical Center
Supported by NIDR Grant 1RO1DE0985 and VA Medical Research

Purpose
v  To determine whether a two implant mandibular overdenture
(IOD) is an effective treatment alternative to a conventional
complete denture (CD) in diabetic edentulous patients
treated with insulin and/or dietary therapy.

Two implants
•  Hader Bar
•  2 clips
•  Experienced denture wearers (15 yrs)
•  Good ridge height (20 mm)

Purpose
v  To determine whether a two implant mandibular overdenture
(IOD) is an effective treatment alternative to a conventional
complete denture (CD) in diabetic edentulous patients
treated with insulin and/or dietary therapy.

Treatment effectiveness was based on improvements in
treatment success rates, masticatory efficiency, food selection
patterns, dietary intake, patient satisfaction, and cost of initial and
maintenance care.

Conclusions

v Theimplant-overdenture in this patient population
and does not greatly improve treatment success,
dietary intake or masticatory function, compared to
conventional dentures.

v More
than 84% of the patients were fully or
moderately satisfied and experienced little or no
discomfort with conventional dentures.

Conclusions

v It is important to not that the patients selected for this study
were excellent candidates for successful outcomes with
It is important to note
conventional complete dentures.
v They were experienced denture wearers and did not present
with advanced resorption of the mandible
v In the following studies not that the patients selected
demonstrated more severe resorption of the mandibular body.
It is therefore not surprising that the outcomes with the implant
retained overlay dentures were more favorable.

Implant Assisted Overdentures
vs.
Conventional dentures
"  95 pts., balanced allocation method, including a control group

Inclusion criteria
l  Severely resorbed mandible (<15 mm)
l  Persistent problems in wearing a conventional
denture (>90% of patients dissatisfied at entry)
Results
l  Increasedsatisfaction with IOD (2 implant overdenture)
l  Improved masticatory performance with IOD
Geertman et al, 1994, 1996

Patient Selection and Treatment Planning
Treatment Options Implant assisted
" Fixed Edentulous Bridge overlay denture
" Overlay Denture
" Implant Supported
" Implant Assisted

Fixed edentulous bridge
Implant supported overlay denture (Fixed hybrid prosthesis)

Which is the best option from a functional perspective?

Implant Assisted Overdentures vs
Implant Supported Overdentures
"  95 pts., balanced allocation method, including a control
group

Results
" The differences with respect to satisfaction, complaints &
subjective chewing ability were not significant.

" No significant difference in chewing ability were noted
between the implant assisted and implant supported
groups Geertman et al, 1994, 1996

Within-subject Comparison Of Mandibular Long-bar and
Hybrid Implant-supported Prostheses: Evaluation Of
Masticatory Function. Tang et al. J Dent Res 1999
Study Subjects:
16 Edent. pts. received CD/IOD(2 implants)
and CD/LBOD(4 implants
Longitudinal design
Within-subject crossover (2 mo.)

Outcome Measures:
Masticatory time (carrot, cheese, bread, apple,
sausage)
Patient based perceptions – ease of chewing
Results:
Masticatory time not different between
prostheses (all foods)
Conclusion: No change in function with increased implant support, but some
perceptual changes are reported

Within-subject Comparisons of Implant-supported
Mandibular Prostheses: Choice of Prostheses
Feine et al. J Dent Res 1994
Study Subjects:
15 edent. patients receive Fixed Bridge and LBOD
(4-5 implants)
Within-subject crossover (2 mo.)

Outcome Measures:
Masticatory time
Masticatory movements, EMG
Patient based perceptions – ease of chewing,
ease of cleaning

Results:
v  Mastication time- LBOD no less efficient than Fixed
prosthesis
v  Pts. find fixed bridge better at chewing harder foods
v  No difference in general satisfaction between the two
types of prostheses
v  Eight pts. chose fixed (stability) and seven chose
removable prosthesis (ease of cleaning)

Summary of Clinical Outcome Data

v  The primary factor in impaired mastication is tooth loss, which will continue
to be a problem and require prosthetic restoration for the immediate future

v  Neither conventional, implant-assisted or implant-supported mandibular
dentures restore masticatory function to dentate levels.

v  There are only limited advantages of one treatment over the other for the
general population.

v  Little well-controlled evidence exist to support a functional benefit of
increased implant support.

Indications for Implant Supported
Overlay Denture

v  Replacement for fixed as patients age and dexterity make it
difficult to properly manipulate hygiene aids
v  Patients with exposure of the inferior alveolar nerve

Fixed vs Removable
Dictated by:
v Estheticdemands
v Psychological demands
v Need for hygiene access
v Oralcompliance
v Quality of the soft tissues

v Cost

Fixed vs Removable
Esthetics
Some patients require the presence of a properly
contoured and extended denture flange in order to
establish proper lip contours.

Fixed vs Removable
Need for hygiene access
" Quality of soft tissues surrounding the implants

When implants emerge through poorly keratinized
unattached mucosa removable overlay dentures are
recommended because oral hygiene access is easier.

Fixed vs Removable
Amount of Keratinized Attached Mucosa

v  Both these patients have little or no attached keratinized
mucosa
v Oral hygiene procedures are much easier to perform when the
implants are surrounded by keratinized attached mucosa.
v Creating a zone of attached keratinized tissues anteriorly would
be beneficial regardless of whether the patient chose fixed
or removable

Fixed vs Removable

v  This
patient presented with ample residual keratinized
attached mucosa. Note that almost both of these
implants have well formed gingival cuffs. If the patient
is capable and willing to properly use the hygiene aids,
fixed also would have been a suitable choice.

Fixed vs Removable

v  These implants emerge through poorly keratinized unattached mucosa.
Previously the patient had been fitted with a fixed edentulous bridge.
Hygiene measures were difficult to perform because of tissue sensitivity.
A removable overlay denture was eventually fabricated. The enhanced
hygiene access allowed by tissue bars design permitted the patient to
maintain healthy peri-implant soft tissues.

Fixed vs Removable
Oral Compliance

v  It is difficult to manipulate the hygiene aids used in patients
with fixed edentulous bridges. If the patient has impaired vision
or impaired motor skills, removable overlay dentures are
recommended.

Fixed vs Removable
Oral Hygiene

v  Oral hygiene must be maintained meticulously. Otherwise
chronic peri-implant gingival infections develop which can
result in considerable morbidity and may even lead to loss of
the implants.

Hypertrophy of peri-implant tissues

Secondary to a combination of:
v  Plague
v  Poor quality peri-implant tissues

Implants in the Edentulous Mandible
Issues of concern
l  Severe resorption
•  Buccal-lingual dimension most important. Less than 5-6 mm requires
bone augmentation
" Lack of attached keratinized tissue
•  Hygiene compromised when the implants are surrounded by poorly
keratinized unattached mucosa
•  Palatal grafts are favored over skin grafts
" Lack of interocclusal space
•  Limits design choices
•  Compromises prosthodontic procedures
•  Commonly encountered when a patient still retains residual dentition in
either the maxilla or mandible
•  Seen in some recently edentulated patients

Severe Resorption
Anatomic Limitations
Severely resorbed mandibular body
a)Vertical height – less than 7 mm
b)Buccal lingual dimension - less
than 5 mm

Mandibles that are smaller than the above are at risk for
fracture during or immediately after implant placement
and should be augmented with a bone graft.

Severe Resorption
The mandible fractured through the left posterior
implant site two weeks following implant placement.

It was reduced and repaired as
shown and healing progressed
normally. An implant assisted
overlay denture was later
fabricated and used successfully
by the patient.

Severe Resorption
Mandibular fractures
v  The use of 5mm diameter implant
was a poor choice for this patient
v  Nothing was to be gained from the
use of a wide diameter implant in
a patient scheduled to receive an
implant assisted overlay denture
v  The appropriate choice would
have been an implant 3.75 mm in
diameter
This patient illustrates the consequences of
poor communication between the surgeon
and the referring dentist and a lack of
understanding of by the surgeon of the
primary means of support provided implant
assisted overlay dentures.

Lack of Keratinized Attached Tissue
l  Palatal grafts are preferred over skin grafts
l  They are best performed at second stage implant
surgery

Lack of Keratinized Attached Tissue
A palatal graft was used to establish a zone of keratinized
attached tissue around these implants. The procedure was
performed at the time of implant uncovering. A surgical stent,
secured to the implants with gold screws, held the graft in
position during the healing period.

Lack of interocclusal space
"  Recently edentulated patients
"  Patients to be fitted with an immediate denture followed by an implant
supported fixed edentulous bridge
"  Patients with supereruption of anterior teeth prior to extraction

v Note the supereruption of the mandibular teeth.
v When these teeth are removed an aggressive alveolectomy needs to be
performed prior to placement of implants.
v Implants should be placed combatable with the plane of occlusion.

Cost Advantage
The most bang for the buck
for edentulous patients is
obtained with a two implant
assisted overlay denture. The
edentulous maxilla is restored
with a conventional complete
denture.

Advantages:
a)  Predictability – Implant
failure rates for this
application are virtually
zero
b)  Patient acceptance is very
favorable
c)  Cost effective
d)  Simplicity

Tissue Bar Design
We favor two implants splinted together with a “Hader” bar,
with the bar aligned parallel to the axis of rotation. The denture
rotates around the bar when the patient generates a posterior
occlusal load. With this design the implant loss rates after
loading are virtually zero.

The anterior, or incisal forces are borne by the implants while
the posterior occlusal loads or born by the primary denture
support areas (retromolar pad and the buccal shelf).

Tissue Bar Design
Hader bar design
In cross section the “Hader” bar is a complete circle and
permits the denture to rotate around it.
Hader clip rotates
Clip around the bar
housing

Plastic burnout pattern
for the Hader bar

This is an implant assisted type tissue bar design. When posterior occlusal forces are
applied, the denture rotates around the bar. As a result the posterior occlusal forces
are supported by the buccal shelf and retromolar pad. The anterior forces are
supported by the tissue bar. Hence support is shared between the implants and the
denture bearing surfaces. The bar provides retention and stability for the denture.

Implant position – Hader Bar Design

v  In most patients there are five implant positions available in
the anterior mandible anterior to the mental foramen
v  We prefer to place implants in the cuspid positions or between
the cuspid and the 1st premolar so that the bar can be
configured parallel to the axis of rotation with little or no
cantilever extension.

These implants are too posterior and too far apart. Since the
denture is only connected to the bar via the clips no clinical
advantage is gained.

The tissue bar fabricated will have
an excessive anterior cantilever.
The excessive cantilever
predisposes to mechanical failures
(screw fractures and implant
fractures).

Implant position
These implants are in ideal position

The implants are wide enough apart to accept two
Hader clips and an anterior cantilever is not
necessary to fit the tissue bar within the contours of
the denture.

Implant position and angulation
v  These implants are in ideal position. They are at least 20 mm apart but
are far enough anteriorly minimize the anterior cantilever.
v  They exit through the crest of the ridge.
v  Implants must not emerge through the mobile tissues of the floor of the
mouth. The tissue mobility at this site is such that the peri-implant tissues
will be in a perpetual state of irritation.
v  Angulation is less important unless “O” ring or similar type attachments
are employed for retention

Implant position
These implants are a bit too close together even
though room is available for the use two Hader clips.

The wider the Hader segment of the bar, the
better the stability of the denture. Ideally, the
Hader segment should be at least 14 mm.

These implants are too close together. Room
is available for only one Hader clip.

Stability of the overlay denture was not ideal
and retention was also suboptimal

Soft tissue problems following 2nd stage
surgery: Solutions:
Peri-implant tissues excessively thick lacking
keratinized mucosa
"  Repeat submucosal resection
"  Free palatal grafts can be used to replace poorly keratinized tissue with
keratinized mucosa
Graft

1 week postop

1 month postop

Other designs
Hader - ERA

v  This design is implant assisted but the addition of ERA
attachments to the posterior extension of the bar will improve
retention.
v  Risk:
v  If followup is not maintained and the denture bottoms out on the ERA
attachments cantilever forces are introduced which could lead to
mechanical failures

Other designs
Hader - ERA
Implant fracture cause:
Functional load exceeds load bearing capacity leading to implant
fracture

Other designs – Unsplinted Implants
v Locators
v Single tooth ERA
v  Retention is good with these two attachments but individual
implants may be exposed to lateral torquing forces. In patients
with poor support the risk of implant overload becomes greater
particularly with the locator type.
v  In addition, if the implants are not parallel to one another as in
these patients, excessive wear as a consequence of insertion
and removal will lead to excessive wear and the attachments.

Other designs –Unsplinted Implants
•  Locators
•  Single tooth ERA
v  Retention is good with these attachments but individual
implants may be exposed to lateral torquing forces. In patients
with poor support the risk of implant overload becomes greater.
v  When occlusal forces are applied unilaterally these forces are
concentrated around the implant on that side.
v  This phenomenon increases the risk of implant overload as
seen in this photo-elastic study assessing locator attachments.

Other designs – “O” Rings
Advantages
"  Favorable stress distribution patterns minimize the risk of
implant loss secondary to implant overload
"  Simple
"  Less costly than a tissue bar

Note: Implants must parallel to one another

Other designs – “O” Rings
Disadvantages
v  Less retention and stability
v  Implants must be parallel or constant insertion and removal results
in rapid wear of the ring
v  Higher profile than tissue bars with UCLA abutment may prevent
proper positioning of the lower anterior teeth
v  Misaligned implants difficult to overcome
v  More maintenance required (Walton, 2003)

Prosthodontic Procedures
“O” ring retained overlay dentures


The dentures are
completed and delivered
in the usual manner.

Delivery and Post-Insertion Care
v  Pressure indicating paste
v  Disclosing wax
v  Clinical remount
v  24 and 48 hour followup
v  Leave dentures out at night
v  Educate the patient

Clinical Remount

Surgical Stents
v The implants must be parallel to one another so it
is imperative that the surgeon use a surgical
template (drill guide) while inserting the implants.

v The mandibular denture is
duplicated and altered as shown to
create the surgical template.
Courtesy Dr. S. Esposito

Impressions
A reline impression can be used to secure the
female portion of the “O” ring to the denture base.

Retentive Anchor
Analog

Final Rubber Base Impression with Laboratory
Retentive Anchor Analogs Positioned in Impression.

Completed Denture

v Relined Denture deflasked with analogs and acrylic flash still
present.
v Completed Denture with the female portion imbedded within
the denture base.

Tissue Bars

Preliminary Impressions
Preliminary impressions are made with transfer type copings
and stock trays.

After the impression is made abutment analogues or fixture analogues,
as appropriate, are connected to the transfer impression copings and
positioned in the impression.

Impressions
v  Transfer type (closed tray)
v  Border
molded impression with corrected
impression made with silicone impression
material.
v  Imbedded type ( open tray)
v  Impression copings are linked permitting the
use of a corrected impression made with
polysulfide.

Imbedded type ( open tray)
Impression copings are linked permitting the use
of a corrected impression made with polysulfide.

Impression copings are secured to
the fixture analogues imbedded in
the preliminary cast


The impression copings are linked together with floss and
Duralay*.


The copings, undercuts and relief
areas are blocked out with wax.


The master impression tray is
completed in the usual manner. The
guide pins must project 1-2 mm
above the level of the tray.

Master Impression
Linked imbedded type impression copings
The impression tray is border molded in the usual fashion, and
the linkedpick up impression copings are screwed onto the
fixtures and the impression is corrected in the usual manner

Completed border molded impression

Master Impression
Linked imbedded type impression copings
A light body polysulfide
impression material can be used
to refine the border molded
impression when linked
imbedded type copings are used.

Appropriate analogues arenow
secured to the pickup type
impression copings that are
imbedded in the master
impression. The impression is
boxed and poured in the usual
fashion.

Impressions

v  When transfer copings for master impressions they must
be inspected carefully to ensure they of imperfections.
v  When transfer copings are used the corrected
impression must made with silicone. Polysulfide is
insufficiently accurate if transfer coping are used.

Pouring the Master Cast

v A separating medium is applied to the
silicone impression to prevent the
Gingitech from adhering to the
impression material.
v The joint between the fixture analogue
and the Impression coping is covered
completely with the Gingitek material.
v The impression is then boxed and
poured with improved dental stone.

Master Cast
The master cast.
The land of the cast
is slightly wider than
normal.

Why?

"   A silicone template with the denture teeth imbedded within
the template will need to be fabricated and this is supported
by the land of the cast .

Record Bases

v  Secure healing abutments of lengths
found in the patient to the master cast.
v  Block out undercuts around the healing
abutments and master cast as needed.
v  Fabricate the record base and wax rims
in the usual manner.
v  The record bases will positively engage
the healing abutments in the patient
helping to stabilize the record base
during the making of the centric relation
records.

Facebow Transfer Record

Make the facebow record and secure the maxillary
cast to the articulator.

Maxillo-mandibular records

Make the centric relation
record and mount the
record on the articulator
in the usual manner

Try-in Appointment
l  Verify the vertical dimension of
occlusion
l  Prove centric relation
l  Make protrusive record and transfer
to the articulator
l  Address the esthetic concerns of
the patient

Occlusal forms
Lingualized with Nonanatomic with
bilateral balance balancing ramps

Selection based on the usual criteria
v  Coordination of the patient
v  Bony contours of the ridges
v  Denture history
v  Jaw relations

Try-in appointment
Prove centric
relation record

With the record in
position the
condyles should be
locked in their
fossae.

Try–in Appointment
The protrusive record is made and transferred to the
articulator.

The condylar inclination is
established and recorded
in the patient’s chart.

Fabricating the Tissue Bar
A silicone template is made using a silicone puddy

Only the anterior teeth
need be recorded in
the silicone template.


The anterior teeth are removed from the record base
and attached to the silicone template. A small amount
of sticky wax will help connect the denture teeth to the
template.

In this example
the tissue bar will
be fabricated with
the use of the
Ucla abutment.

Begin by attaching the Ucla abutment to a fixture analogue with a
long guide pin (screw). Apply a thin layer of Duralay to the Ucla
abutment and extend it 2-4 mm onto the guide pin.

Secure the Ucla abutments to the
fixture analogues in the master cast
with an abutment screw.

The silicone template can be repositioned as
necessary when developing the wax pattern
for the tissue bar.

v  The cast is surveyed and a proper path of insertion is
selected
v  The plastic pattern is attached to a specially designed
instrument that in turn is attached to the surveyor.
v  The plastic pattern can then be secured to the Duralay so
as to be compatible with the chosen path of insertion

v  A plastic burnout Hader bar
pattern is cut and shaped to fit
between the two implants
v  The bar should be positioned
beneath the denture teeth so as
. not to displace them or alter the
contours of the denture base

Design of the Tissue Bar
v  The tissue bar is designed to be implant assisted
v  As such the denture should rotate freely around the
bar when posterior occlusal forces are delivered
v  To idealize this rotation the bar should be oriented
perpendicular to the midline and parallel to the plane
of occlusion
v  There should be space beneath the bar and the
tissue to ensure appropriate hygiene access
v  If
the bar touches the tissue bar bacterial plagues will form
on the undersurface of the bar which will irritate the tissue
and ultimately lead to hypertrophy of these tissues
v  The
portion directly associated with the implants
may need to be tapered anteriorly to allow for
placement of denture teeth

Configuration of the bar
"  Parallel to the plane of occlusion
"  Perpendicular to the midline
"  There should be ample space beneath the bar to provide for proper
hygiene access

Occlusal
plane

Midline

The left implant is slightly more posterior than desired

However the configuration of the bar remains the same
"  Parallel to the plane of occlusion
"  Perpendicular to the midline
"  There should be ample space beneath the bar to provide for
proper hygiene access

The left anterior implant is more labial than desired

The basic configuration of the bar remains the same
v Parallel to the plane of occlusion
v Perpendicular to the midline
v There should be ample space beneath the bar to provide for proper
hygiene access

However, the tissue bar portion over the left implant is tapered
to accommodate the positioning of the denture teeth.

Fabrication of the Tissue Bar
Tissue bars must be parallel to the plane of
occlusion and perpendicular to the midline.

Note how the labial portion of the bar is tapered over the left
implant bar. This allows for proper positioning of denture teeth.

Fabrication of the Tissue Bar
Completed tissue bar.

Note the hygiene access beneath the bar.

Processing
l  Prior
to processing the clip housings are
secured to the bar and the rest of the bar
is blocked out with plaster or stone.

Completed dentures-Delivery Sequence

v  Ensure that the denture rotates
properly around the tissue bar
as designed
v  Connect the tissue bar to the
implants
v  Two stage tightening procedure –
At delivery and 1-2 weeks later
v  Pip denture bases
v  Use disclosing wax to verify
border extensions
v  Clinical remount and refine the
occlusion

Delivery Sequence
Check to ensure the bar fits properly within
the denture base

Make sure the bar rotates freely within the retentive clips.
This ensures that the overly denture will indeed be implant
assisted rather than implant supported.

Delivery Sequence
Pressure Indicating Paste (PIP)

Using pressure indicating paste (PIP) to eliminate areas of
excessive tissue displacement or undercut areas that may be
traumatized during insertion and removal of the denture.
The most critical undercuts relative to the path of insertion in an
implant retained denture are generally located anteriorly.

Delivery Sequence
Pressure Indicating Paste (PIP)

The mylohyoid area is always an area of
concern and must be carefully adjusted.

Delivery Sequence
Disclosing wax is used to check the length, thickness
and contour of the denture border

This border slightly This border is of
overextended and proper length but
a little thick excessively thick

Clinical Remount

Using remount casts and
a facebow transfer
record, mount the upper
cast, obtain and new
centric relation record and
mount the lower cast.

Clinical Remount
These are anatomic posterior denture teeth

Equilibrate in centric

Clinical Remount
These are anatomic posterior denture teeth

Equilibrate in
working, balancing
and protrusive.

Patient instructions
v Leave dentures out at night
v Hygiene of the tissue bar and the dentures
v Follow every 4-6 months

v  Clips need to changed about every 6-12 months
v  Denture teeth wear out 7-10 years
v  Tissue bars wear out 12-15 years.

Indications for Implant Supported
Overlay Denture

v  Replacement for fixed as patients age and experience
difficulty manipulating hygiene aids
v  Patients with exposure of the inferior alveolar nerve

Implant Supported Overlay Dentures
Biomechanical requirements
Minimum of 4 implants
Minimum of 1 cm of Anterior Poster A-P) spread

Design Considerations
v  The tissue bar requires more bulk between the implants
because of the increased forces delivered.
v  Hygiene access between the implants and beneath the bar
is required
v  We prefer Hader attachments because of their low profile

v  Bite force of patients with implant supported prostheses is
greater
v  Therefore it may be advisable to provide metal reinforcement
particularly if interocclusal space is compromised


The bars must be designed to have good hygiene
access between the implants and no portion of the
bar may touch the underlying tissue.


Completed overlay dentures inserted.


v Anatomic posterior teeth
v Bilateral balanced occlusion

The 4 implant assisted overlay denture
v  Four implants splinted together
with a implant assisted overlay
denture.
v  In this design the “Hader”
segment anteriorly serves as the
axis of rotation. The resilient
“ERA” attachments posteriorly
allow the prosthesis to rotate
around the Hader segment when
posterior occlusal forces are
applied.

v This approach is generally not recommended
v No significant gains from the perspective of mastication
v We only recommend this approach when the implant sites are dramatically
compromised. For example: Patients treated with cancero-cidal levels
of radiation.

Coming soon
v Implant Biomechanics and Treatment
Planning in partially Edentulous Patients
v Abutment selection in partially edentulous
patients
v Early and Immediate loading

v  Visitffofr.org for hundreds of additional lectures
on Complete Dentures, Implant Dentistry,
Removable Partial Dentures, Esthetic Dentistry
and Maxillofacial Prosthetics.
v  The lectures are free.
v  Our objective is to create the best and most
comprehensive online programs of instruction in
Prosthodontics

Edentulous Mandible - Overlay Dentures

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