Republic of Iraq

Ministry of Higher Education

& Scientific Research
University of Baghdad
College of Dentistry
________________________

Copy denture
An undergraduate project submitted to the Council of College of
Dentistry at the University of Baghdad in partial fulfilment of the
requirements for B.D.S degree.

___________________________
By:
Aya Mohammed Abdullah
_______________
Supervised by :

Lecturer Dr.Ghazwan Adnan Alkinani

B.D.S., M.Sc., Ph.D. Prosthodontics

2021 A.D 1442 A.H

 Dedication
________

My Father
My Mother soul
My Grandfather
My Uncles
My brothers

They shared all my good & bad moments. They

supported me a lot & finally thanks to those who
were by my side, to my first hero, my father

Aya
 Acknowledgment
First of all, praise is to all mighty ALLAH, for the
wisdom he bestowed upon me, the strength, the
peace of my mine and good health in every step of
my journey. May peace and salutation be given to
the prophet Muhammad, the last prophet who is
the idol for all of us.
My thanks to Prof. Dr. Raghad Alhashimi, the dean
of college of dentistry, university of Baghdad and
to Pro. Dr. Ghasan Abdulhamed Altaai, the head of
department of prosthodontics.
My gratitude to all the members of the scientific
committee of the prosthodontics department, for
high ethics and all the help.
Finally, I would like to express my deep
appreciation and gratitude to my research
supervisor Dr.Ghazwan Adnan Alkinani for his
unlimited cooperation and support to write this
research and for all the help
List of Content
Introduction

The treatment for patients with complete dentures has challenges to the
skills of the dentist, since one concern is the clinical and technical aspect
of denture fabrication; the other is the general physical health, local oral
factors and psychological well being of the patient. These latter factors
can be as important as the clinical and technical treatment aspects in
the potential success of treatment. Therefore the need for fabricating
copy denture is a must to reduce the challenges mentioned (Soo and
Cheng 2014).

Copy denture is not a single technique, but a variety of techniques

designed to replicate complete dentures (Soo and Cheng 2014). A
range of techniques both clinical and laboratory exist which vary in
their ability to “copy” a prosthesis. These techniques allow favourable
features from an existing denture to be copied (for example, the shape
of the polished surfaces) while also allowing for alterations to less
favourable features (for example, worn occlusal surfaces). Therefore, it
is important to identify patients who may have difficulty adapting or are
unwilling to learn new skills, in these cases, existing dentures are
extremely valuable for diagnosis and treatment planning (Vohra and
Habib, 2013). Copy dentures enhance neuromuscular adaptation to
new dentures, reduce patient-clinician chair side time, reduce
laboratory steps, require fewer patient visits, make jaw relation
registration simple, provide technical staff with more guidance to tooth
position and moulds, allows for copying esthetics and are cost effective
(Vohra and Habiba, 2013), (Özkan et al., 2018), (Ablonski et al.,
2018).
Moreover, adapting to new dentures can be challenging for patients
especially for those with long serving dentures (Ablonski et al., 2018).
It has been suggested that older patients may experience difficulties in
adapting to new dentures due to a reduced capacity for learning new
muscle activity patterns. Since a new prosthesis requires the
development of a new learning sequence and the willingness to be
persistent, simultaneously, evidence suggests that utilising ‘copy’ or
‘replica’ techniques may help older patients adapt more easily to new
dentures (Vohra and Habiba, 2013), (Ablonski et al., 2018).

Most existing dentures, whether or not they have been worn

successfully, provide extremely valuable information for all stages of
treatment. These patients will benefit from treatment that makes
minimal change from the old to new dentures, such as the use of the
Copy (duplicate) Denture technique because it makes an easier
transition to the new prosthesis.

Patient satisfaction with new complete dentures has a strong

relationship with the quality of new dentures and also the residual
mandibular alveolar ridge, the satisfaction level is higher to the patients
with replacement complete dentures fabricated by copy denture
technique as compared to replacement complete dentures fabricated by
conventional technique (Syed and Azad, 2009).
Aim of the study :

Investigation the copy denture technique and determine the techniques

that were used over the years and the development of these techniques
according to the advanced technologies.
 Chapter One

Review of literature
1.1 Historical background:

The advancement of technology and the need to comfort the patients led to
the development of several techniques of copy denture over the years.
(Adam, 1958) found a means for constructing a duplicate denture. (Shaw,
1962) made a technique of copy dentures for immediate denture using
acrylic resin teeth. In the 1970s many dentists and technologists developed
many techniques of copy dentures (Wagner, 1970), (Azarmehr, 1974),
(Wilson and Anderson, 1975), (Boos and Carpenter, 1976).
Krug in 1984 described the Ceramic flask technique for duplicating
acomplete denture “this technique describes a simple, one-visit, inexpensive
procedure with which an existing complete maxillary or mandibular
denture,therefore the resulting duplicate denture is not a spare prosthesis for
the patient, but serves the dentist as a valuable adjunct in subsequent
treatment procedures at chairside and in the laboratory”. (Lindquist et al.,
1997) described Denture duplication technique with alternative materials,
using addition silicon instead of condensation-curing silicones or
irreversible hydrocolloids materials; the average time required for this
duplication technique is approximately 45 minutes “The duplicate denture
can now be processed at a convenient time because the impression materials
have long-term dimensional stability”.
A modification in the above technique was given by (Nassif J and
Jumbelic R., 1984). The change was in the fabrication of the teeth before
going ahead with the flasking procedure. Soo and Cheng in 2014 have
also discussed a technique wherein they used selective pressure technique
and zinc oxide eugenol impression paste to make secondary impressions in
clear acrylic copies of existing dentures of the patient. Yet, there are more
modern techniques as well which had an impact on the fabrication of the
copy denture.
1.2 Definition:

The copy technique (or copy dentures) refers to duplication of an

existing denture(s) with or without modification of the existing denture.
They are a faster alternative to a remake of complete–complete acrylic
dentures. The purpose of the copy technique is to reproduce as closely
as possible the polished surface shape of the old dentures in the new
dentures (Özkan et al 2018).

1.3 Aims of Duplicating Denture Fabrication:

● Obtaining the right maxillomandibular relations by the correction of
the occlusion.

● Minimizing adaptation problems by producing a new denture that, as

far as possible, resembles the old one (The shape of the base, the form of
the palatal vault, the transfer of teeth regarding axial inclination, shape,
form and arrangement are all important.)

● Uniting some stages of the production process and fabricating the

denture within a few clinical visits (Özkan et al 2018).

1.4 indications:

1.4.1 Situations where copy dentures are advisable:

● Correct position of teeth in the neutral zone or correct zone of

adaptation and the polished surfaces are satisfactory.

● Loss of retention in otherwise favourable dentures requiring

replacement.
● Wear of the occlusal surfaces.

● Replacement of immediate dentures.

● Spare set of dentures(Özkan et al 2018).

1.4.2 dentures:
Typical dental history that would suggest an indication for copy

● Elderly patients presenting with satisfactory complete dentures.

● Worn occlusal surfaces, indicating long-term acceptability.

● Deterioration of dentures base materials.

● Patient requests a“spare set“ of dentures.

● Patients with a history of denture problems make controlled

modifications to copy previously most successful dentures (Özkan et al
2018).

1.5 Contraindication:
Any serious defects of the denture prosthesis.. So careful evaluation
of hard and soft tissues and the prosthesis is done before duplication
(Özkan et al 2018).

1.6 Advantages and disadvantages:

Copy denture technique has benefits and problems for both dentist
and technician as the following:
 Table (1.1): Advantages and disadvantages (Özkan et al 2018).

Advantages Disadvantages

No alteration or mutilation of The copy technique itself (some

existing dentures. dentists have never been taught
this technique as undergraduates)

No period for patients without Attempting the impossible, by

their dentures. using the copy denture technique
in a patient for whom it is clearly
not indicated.

Three clinical stages. Some flasks are very expensive.

Simple duplication procedure, Hard to find a laboratory that is

less time than conventional comfortable with the technique
impressions. and the cost charged by the
laboratory.

No individual trays or record Not all patients are suitable for this
blocks are required. denture construction.

Infrequent re-articulation of Inadequate information on the

teeth for try-in necessary. prescription.

Elimination of repolishing after Crucial assessment of existing

border adjustments. dentures.
No thickening of palate in the
finished dentures, as occurs in
some reline procedures.
Only two laboratory stages.

1.7 Materials used in copy denture fabrication

Several materials used during the fabrication, and these materials

will be discussed as the following:

1.7.1 Mould Materials

Different materials were used for the preparation of mould for

duplicating dentures. In the early years, plaster and stone were used as
a mould material, however the conventional flasking technique of
ordinary denture was used. Later; other methods were used with cold
cure acrylic resin in flexible hydrocolloid moulds. (Wagner A, 1970)
used both reversible and irreversible hydrocolloids for the preparation
of the mould. Reversible and irreversible hydrocolloid were used such
as shellac base; alginate by (Wilson LG, Anderson GA, 1975), (Boos
RH and Carpenter HO, 1976), (Nassif J and Jumbelic R, 1984). Also,
Silicon was used by (Manoli and Griffin 1969).

1.7.2 Containers of the mould materials

Various containers were used; ordinary flasks when heat cure

acrylic was used, cup flask or perforated tray for holding alginate or
flexible mould material, interlocking bowels especially designed for
duplication were also used, or special container which has tapered sides
outwards from the base to the top with opened base and top to facilitate
easy removal of hydrocolloid material, modified denture
flask,disposable plastic tray were also used.

1.7.3 Denture base material

Heat cure acrylic denture base was the material of choice for
denture base of duplicate denture, Later on, evolution of flexible mould
materials lead to the use of cold cure acrylic denture base, Pourable
resin which is a type of cold cure resin was also used with hydrocolloid
mould material, but with high residual monomer content with inferior
mechanical properties and possibility of distortion, in spite of short time
of denture removal of denture from the flask, with less effort and less
finishing.

1.8 Techniques for fabrication the copy denture

1.8.1 Techniques during the 20s century:
There are numerous techniques or methods that are used in
fabrication of copy denture, and the majority of these techniques are
similar except in the use of mould containers and materials. There were
two main techniques that were used during the 20th century which are:
auto-polymerization acrylic resin and heat cure acrylic resin.

1.8.1.1 Modified flask method using silicone impression

material
Manoli and Griffin in 1969 explained a modified flask method
using silicone impression material for denture duplication. Silicone
rubber was painted on the tissue surface of the denture and reinforced
with dental stone. The denture with the silicone rubber lining and stone
cast was invested in the lower half of a flask. A uniform layer of silicone
rubber approximately 3-4mm thick was applied to the polished surfaces
of the denture and to the teeth. The upper half of the flask was placed in
position on the lower half and the flask was filled with plaster. After half
an hour, the denture was removed from the flask and the teeth of the
same shade and mold were placed. The mold was filled with a “pour-in”
type of autopolymerizing resin and the flask was closed and held under
pressure until the resin set. The duplicate denture was removed,
trimmed and polished.
1.8.1.2 Pour resin flask method
Boos and Carpenter in 1974 designed a special flask to be used
with reversible hydrocolloid for making the mold. Tooth
shade-autopolymerizing resin was painted into the tooth indentations
with a brush and pour type of autopolymerizing resin was used to form
the duplicate denture in the mold. The disadvantages involved were the
requirement of a special flask and the equipment and formation of voids
in the denture.

1.8.1.3 Cup flask method

Wagner in 1970 described a method of duplicating complete
dentures by using cold-curing acrylic resin tray material in hydrocolloid
molds and a cup as a flask. Which then (Singer, 1975) has modified the
method by introducing a particularly convenient zipper technique that
uses dental floss to section an alginate irreversible hydrocolloid mold
poured in a 12-ounce ceramic cup. Pour type of resin and tooth colored
autopolymerizing resins were used to fabricate the duplicate dentures.

1.8.1.4 Modified flask method

Brewer and Morrow in 1975 in their technique modified the
denture flask by removing a rectangular section from the upper part to
provide access for the sprues. Sprues made of utility wax with a
diameter of 15 mm were attached to the lingual surface of the heels of
mandibular dentures and to the palatal surface of the tuberosity region
of maxillary dentures. After mixing and placing the alginate into the
fitting surface of the denture and setting of the alginate. The upper part
of the flask was placed in position, and the wax sprues were adapted to
seal the rectangular opening. Alginate was mixed and poured into the
flask.
slowly. After the alginate had set, the flask was opened, and the denture
and sprues were removed. Autopolymerizing tooth-colored resin of the
proper shade was added to the teeth indentations by the sprinkle-on or
paint-on method. Pour-type resin was mixed and poured into one sprue
until the resin filled the mold and extruded through the other sprue. The
denture was cured at 20 psi for 30 minutes (Brewer et al., 1980).
(Nassif J and Jumbelic R., 1984) have modified the above technique,
the change was in the fabrication of the teeth before going ahead with
the flasking procedure.

1.8.1.5 The soap container method

In this method of denture duplication the original denture borders
are modified with green stick compound. It is then submerged in
alginate in the soap container, denture invested in the lower part of the
container. A second pour of alginate to complete the investment. The
soap container should be pressed from sides to avoid its distortion. Two
halves are then opened and the sprue holes are cut with a sharp knife.
The halves are then re-assembled and can be held together with elastic
bands. Self-cure resin is being poured down one of the holes with light
vibrations, while air escapes from the other. Place the container with
the sprue holes upright in a pressure pot that contains water at 110 F
and process the resin under 15-30 psi pressure for 30 minutes. The
waxed or auto-polymerized duplicate dentures are then recovered from
the moulds. The wax teeth on one of the dentures are then replaced
with the identical mould of the resin teeth. (Nassif and Jumbelic,
1984).

1.8.1.6 Two tray method.

Cooper and Watkinson in 1976 introduced a technique in which
they used two impression trays along with the impression material and
the sprued
denture to be duplicated to create a mold. This technique was later
modified by Lindquist in 1997 where he used a layer of putty
consistency polyvinyl siloxane impression material and also lined the
tissue surface of the denture with light bodied polyvinyl siloxane
impression material to create a mold space (Lindquist et al., 1997).

1.8.1.7 Flask method

Azarmehr P & Azarmehr HY in 1970 used two identical flasks with
interchangeable sections for denture duplication. By using two identical
flasks: A, upper section of original flask; B, lower section of original flask:
a, upper section of duplicating flask; and b, lower section of duplicating
Flask then the identical flasks were interchangeable.

1.8.1.8 A technique by Izharul Haque Ansari

Izharul Haque Ansari in 1994 used a technique where it required
no special equipment or material for duplicating the old dentures to
make replica dentures. Used plaster as investing material lined by putty
soft material with wire loops inserted as retention for wax denture as
they mounted on articulators and teeth replaced with acrylic resin teeth,
tried in mouth and processed in the usual way.

1.8.1.9 A technique by Lindquist TJ and Ettinger RL

Lindquist TJ and Ettinger RL in 1999 used additional silicon instead of
condensation silicon because additional silicon is more accurate,
dimensionally stable, can be used several times without loss of accuracy
and can capture the necessary details even with over denture
abutments, finally it is easy to use and requires no special equipment.
1.8.2 Modern Techniques
Some of the demand for sophisticated treatment has come from
media coverage, especially the electronic media. Rapidly advancing IT
developments will supersede current technologies, but all must be
developed with a conscious demand for evidence-based care

1.8.2.1 Duplication procedure for complete denture by

CAD/CAM
Computer-aided design (CAD) computer aided manufacturing (CAM)
technologies have been applied in the field of prosthodontic since the
1980 (Inokoshi et al., 2012).
Kawahata et al., in 1997 in their study, used the method where
shapes of the complete dentures of an edentulous patient were
measured using non-contact type shape measurement system and
morphological data at the interval of 0.25mm were obtained in the
X-axis and Y-axis directions, measurements were performed from the
occlusal surface and mucosal surface sides based on the 3-dimensional
morphological data, cutter patches for cutting were generated, the 3
steps method consisting of rough cutting, finish cutting and partial
finish cutting was used for duplicating the dentures, the modeling wax
was cut using a computerized numerical control (CNC) processor and
ball-end mills with diameter of 6mm and 1mm.Although further
improvements are needed in the measurements and cutting in acute
slope areas, the duplication of complete denture appears to be possible
using CAD-CAM system.
CAD/CAM has gained in importance to meet various demands for the
different dental disciplines (Wesemann et al., 2017). It was also
estimated that direct digitalization with intraoral scanners is
demonstrated to be a suitable alternative, although it requires more
chairside time and does not result in a
higher level of accuracy than an indirect workflow with desktop
scanners (Wesemann et al., 2017). In the CAD/CAM technique the
maxillary and definitive mandibular impressions and the occlusal rims
were prepared for scanning with scan spray in the laboratory, then
scanning was performed with an optical 3D scanner. The files from the
laser-scanned maxillary and definitive mandibular impressions and
connected occlusal rims will be translated into stereolithography (STL)
files then the denture will be virtually designed using 3D viewing
software as shown in figures below (Janeva et al., 2017).
 Figure (1.2): Preview of virtually designed dentures (Janeva et al., 2017).

1.8.2.2 Sectional mold technique

Mohamed TJ and Faraj SA in 2001 used a sectional mold and
dental stone to invest the denture, and heat-activated acrylic resin is
used to duplicate both the denture teeth and base. This technique allows
the fabrication of a duplicate denture by using the superior properties
of heat activated acrylic resin. The only disadvantage of this technique is
the risk of fracture of the master cast when undercuts are present. Given
this risk, the technique is preferable for situations in which there are no
undercuts.

1.8.2.3 A Duplication Method Using “Appropriatech”

Owen in 2006 used Appropriatech (appropriate technology) saving
cost and time by using box tray and alginate to take impression of the
polished

surface, putty material for the fitted surface, paper clips as retention
mean for plaster support, wax sprue added, and a mix of modeling wax
and 10 % sticky wax are mixed and poured into the mould, The 2 halves
of mould are separated to reveal a wax replica of the denture, every
other tooth is replaced to help maintain arch form and tooth position,
final impression of the new denture is made with ZnOx inside the trial
base. The technique is cost effective with only 3 visits, but the final
impression with wax intermediate dentures of weak point as a high
percent of distortion can occur while taking impression and vertical
dimension verification.

1.8.2.4 3D printed copy denture

Andrew et al., in 2017 stated that “3D printed copy denture
templates reproduced the original polished surfaces and occlusion with
greater precision than either of the conventional techniques” based on
the study conducted to investigate and compare the accuracy of
traditional copy denture techniques with the relatively new technology
of scanning and 3D printing a copy denture template and concluded that
3D printed copy denture templates reproduced the original denture
with significantly greater trueness and precision, regardless of which
error metric was used. Andrew made six copies of a single upper
complete denture that were reproduced by the three methods (two
conventional and one digital) under investigation. The first method used
a traditional ‘copy denture technique’ including the use of impression
trays to provide support for the material. The second method used
unsupported impression material. In both conventional methods,
impressions of the polished surface of the denture were recorded using
a laboratory silicone putty which is condensation-cured. The maximum
error was significantly lower with 3D printing, than with the traditional
copy technique as shown in figure(1.3).

Using the typical colour maps of the errors produced by each method of
denture template production are shown in figures(1.4, 1.5, 1.6). visual
comparisons of the colour maps showed distinctive distributions of
error within the different groups. Both CT and CNT templates showed
errors on polished surfaces, most noticeably in the palate. Yet, 3D
printed copy denture templates reproduced the original polished
surfaces and occlusion with greater precision than either of the
conventional techniques
.
Figure (1.3): overview of the methods for creating traditional and 3D printed,
copy denture templates (Andrew et al., 2017).
 Figure (1.4): Typical reproduction errors for conventional copy denture technique
without a supporting impression tray (Andrew et al., 2017).

Figure (1.5): Typical reproduction errors for conventional copy denture technique
with a supporting impression tray (Andrew et al., 2017).
Figure (1.6): Typical reproduction errors for 3D printed copy templates.
(Andrew et al., 2017)

The use of a general-purpose handheld optical scanner and a 3D printer

in duplicating complete dentures has been proven to be effective
(Kurahashi et al 2017). In this research, they introduced a clinical
procedure for fabricating duplicate complete dentures using a
general-purpose handheld optical scanner and a 3-dimensional (3D)
printer in the dental clinic setting. Before the image capturing, the
denture was coated with siccarol powder to facilitate the scanning, then
A handheld optical scanner was equipped at the focal point of the
denture to digitize the surface topography of the denture. Then after
scanning, the 3D data was integrated on the computer and the 3D
denture form was constructed using the specific software. This
procedure has the advantages of wasting less material, employing less
human power, decreasing treatment time at the chair side, lowering the
rates of contamination, and being applicable readily fabricated at the
time of the treatment visit.
Figure (1.7): (a) Layout of denture and scanning devices for digitalization (white
arrow: rotary table, and black arrow: handheld optical scanner), (b) setting of lower
denture, (c) setting of upper denture powdered with siccarol (Kurahashi et al
2017).

Figure (1.8): 3D images of the upper and lower complete dentures

(Kurahashi et al 2017).
Figure (1.9): Computer-aided modification of the denture form on the monitor
(Kurahashi et al 2017).

The difference from the conventional methods here is that the

conventional fabrication procedure of duplicating a denture has a series
of technical steps: impression, moldmade, injection of denture material,
and re-contouring and polishing according to a lost wax technique. The
new method consists of just two steps: digital impression of the existing
denture by using a handheld optical scanner, and fabrication of
duplicating PLA denture using a 3D printer.

Takeda in 2019 stated that Digitally duplicated dentures were

predictably and efficiently produced by using the replication technique
with 3D scanning and printing and the application of this technique may
reduce both clinical and laboratory time based on an accurate diagnosis
of the problem and an understanding of the advantages and limitations
of this technique. During the study, Takeda used Milled monolithic
prepolymerized PMMA acrylic resin possesses higher mechanical
strength that is not subject to polymerization shrinkage which would
negatively affect denture base adaptation and accurate tooth position
and another advantage of this material was to have fewer porosities and
surface roughness, these improvements translate clinically to stronger
dentures, with reduced potential to harbor microorganisms and the
resulting oral infections (Srinivasan et al., 2018), (Steinmassl et al.,
2018), (Takeda et al., 2020), . It was estimated as well that digital
fabrication has advantages inherent to its digital nature, including
efficiency, decreased dimensional inaccuracy, and an STL file that can be
modified to alter the denture and used for future treatment. However,
the disadvantage of this technique is that it’s costy.

1.9 Comparison of Patients Satisfaction with copy denture

technique versus the conventional technique Many people requesting
new complete dentures will have worn dentures (often the same set)
successfully for many years.’ Patients generally expect new dentures to
fit, function and look better than their existing dentures. When
replacement dentures become necessary, it is helpful if the new
prostheses require as little adaptation as possible to the existing skills.
This is generally considered to be particularly important for the older
patients in whom not only many skills have been developed over a long
period, but also the ability to relearn may be diminished (Syed and
Azad, 2009). When this study was conducted, it was obvious that the
patients satisfaction level is higher with the replacement complete
dentures fabricated by copy denture technique as compared to
replacement complete dentures fabricated by conventional technique
that because copy denture technique presents savings in clinical time,
offsetting an increase in material costs, and no penalty in laboratory
expenses. Copy denture technique does provide a reduction in
discomfort during treatment, and during adaptation to the completed
appliances. According to oral health impact, there was little difference in
the outcomes of new dentures made by either the copying or
conventional techniques on the OHIP based on a study by (Scott et al.,
2006). However, in the copy denture group, there was a significant
improvement of the OHIP score in relation to embarrassment.
Current dentures:
The upper and lower dentures were stable, retentive and
well-supported. With both dentures in situ the appearance, centre line
and occlusal vertical dimension (OVD) were acceptable as shown in
figure (1.11). The occlusal plane and incisal level were satisfactory.
There was a partial fracture in the midline of the upper denture
palatally as shown in figure (1.12).

Diagnosis:
The following diagnoses were made:

1- Fractured upper denture and stained lower denture.

2- Poor occlusal scheme not ideal for removable complete prostheses.

a b
Figure(1.10): (a and b)-represent the upper and lower arches U-shaped
with well-formed minimally resorbed ridges showing signs of scalloping
where the natural teeth were present. The ridges were firm and the
mucosa healthy (c)– represent edentulous ridges at approximate final
vertical opening (Soo and Cheng, 2014).

(1.11)
 (1.12)

Figure (1.11 and 1.12): Current dentures in ICP and Current upper denture
showing fracture palatal to upper centrals respectively (Soo and Cheng, 2014).

C. Treatment plan:
The treatment plan is outlined below:
1. Repair existing upper denture to be kept as a spare.
2. Construct new upper and lower dentures using copy technique to
replicate tooth position and polished surfaces, but allow for minor
improvements to mould, shade and arrangement.
3. Take wash impressions to improve accuracy of fit surface with ZnOE
using open mouth technique. 4. Ensure balanced occlusion and
articulation at the same OVD.
D. Treatment:
● Make clear acrylic copies of existing dentures in laboratory silicone.
Heavy bodied silicone is rigid enough to be used without additional
support as shown in figure (1.13). However, if extra rigidity is required
then two large stock trays for each denture can be used to contain and
support the impression material.

● Take wash impression, after reduction of any undercuts, with ZnOE

using open mouth technique as shown in figures (1.14 and 1.15). The
acrylic copies are effectively used as close-fitting special trays. They
must have the undercuts removed prior to the wash. A fluid wash
impression material is used to ensure a thin impression which will not
significantly increase the OVD and also capture the denture bearing area
accurately. Pressure relief holes in the palatal vault will aid escape of
material, reduce pressure build up and ensure a thin impression. An
open mouth technique is clinically easier to perform than a closed
mouth technique the advantage of which it is thought will minimise
changes in the OVD.

● Take jaw registration as shown in figure (1.16) at the same visit as

step two. Maintain the same OVD. Silicone jaw registration material to
be used. The acrylic copies serve a double purpose as the registration
block as well as special tray. If the OVD has increased then it will have to
be reduced with an acrylic bur and balanced occlusal contact developed.
The choice of jaw registration material is up to the clinician.

● Facebow record and mounting on semi-adjustable articulator in

order to make sure that jaw registration material will allow separation
of the dentures. Silicone will allow this to be done cleanly and easily.

● Tooth-try in wax to verify tooth position and OVD. Tooth mould and
shade information can be taken from the existing dentures, however,
the patient may have his preferences accordingly to take into
consideration.
● Finish in pink veined high impact acrylic and delivery of dentures.

Figure (1.13) : clear acrylic copies were made for

both upper and lower jaw (Soo and Cheng, 2014).

Figure (1.14): ZnOE Figure (1.15):ZnOE

wash in upper jaw wash in lower jaw
(Soo and Cheng, 2014).
Chapter Two
Discussion
● Many techniques have been reviewed and found for fabrication of
the copy denture over the years. There were different materials used
while the fabrication, specially the materials used in the mould
preparation, containers of the mould and denture base preparation.

● While selecting one of the methods or techniques used to duplicate a

denture, it is important to consider the intended use of the copy denture,
the degree of accuracy required, and the materials and time available to
the clinician.

● Further investigation is required into understanding the distribution

of errors produced from the rapid prototyping process and how these
errors will affect clinical management of a patient.

● Further investigation is required to realize the digital use in copy

denture more and find if there will be any error or advancement to
make.

● There are huge advantages of the digital use in copy denture

fabrication, which include wasting less material, employing less human
power, decreasing treatment time at the chair side, lowering the rates of
contamination, and being readily fabricated at the time of the treatment
visit.

● This technology eliminates the need to take physical impressions for

copy dentures. As the price and convenience of accurate chairside
scanners reduces, it is anticipated the technique will slowly infiltrate
primary care dental practices.

● Any serious defects of the denture prosthesis. So careful evaluation

of hard and soft tissues and the prosthesis is done before duplication.

● Duplicate dentures are greatly appreciated by patients who fear the

embarrassment of being without their denture.
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