braided cord and twisted cord.
• Selection of the type of retraction cord depends on the clinician’s
• Largest cord which can adequately physically displace the gingiva
• There are a number of chemicals which are used to impregnate the
retraction cord to produce effective haemostasis.
Criteria for selecting appropriate retraction material
• It should effectively displace gingiva and produce haemostasis.
• It should not irreversibly damage the gingiva.
• It should not produce any systemic side effect.
• Chemicals which are commonly used with the retraction cord to
provide adequate displacement of the gingiva are aluminium,
potassium sulphate, aluminium sulphate, aluminium chloride and
• Although epinephrine is commonly used, its potential to produce
systemic side effect has been questioned recently.
• It produces haemostasis and causes local vasoconstriction, resulting
in transitory gingival shrinkage.
• It causes increase in blood pressure and heart rate.
• The amount of epinephrine absorbed depends on the area and time
• Patients on monoamine oxidase inhibitors or tricyclic
• Patients on beta-blockers or cocaine
• Diabetic or cardiovascular patient
• Patients hypersensitive to epinephrine
Technique of using retraction cord
• The operating field is kept dry by using high-vacuum suction and
• Around 5 cm of retraction cord is drawn from the dispenser bottle.
• It is moistened by dipping in 25% of aluminium chloride solution.
• The retraction cord should not be touched with gloves, as latex
inhibits polymerization of elastomeric impression material.
• Cord is looped around the prepared tooth.
• Gently the cord is slipped into the sulcus using a cord-packing
• Cord is first tucked in the mesial side and then moved buccally,
• Cord packer should be inclined towards the area where the cord has
• Cord is left in the mouth for 10 min and then removed slowly (Fig.
• The impression material is injected in dry and clean sulcus area.
• An impression is made of the prepared tooth with a material of
FIGURE 26-2 Position of retraction cord in the sulcus.
Surgical method of gingival retraction
Surgical method of gingival retraction is of two types:
• The aim of this method is limited removal of the epithelial tissue in
the sulcus while creating the chamfer finish line.
• This method is also called gingettage.
• It should always be done on healthy gingival tissues.
• The method was first described by M. Amsterdam in 1954.
• It was developed by F.J. Hansing and R. Ingraham.
• There should be no bleeding on probing.
• Sulcus depth should be less than 3 mm.
• The patient should have adequate keratinized gingiva.
• It is usually done along with cervical margin preparation.
• Torpedo diamond bur is extended into the sulcus up to half of its
depth to remove the epithelium.
• Chamfer finish line is formed along with the removal of the sulcular
• Abundant water spray is used during preparation.
• Cord impregnated with aluminium chloride is placed in the sulcus
for 4–8 min to control haemorrhage.
• It has poor tactile sensation.
• There are chances of injuring the periodontium.
• It is used to enlarge the gingival sulcus by controlled tissue
destruction to facilitate impression making (Fig. 26-3).
• It consists of a high-frequency oscillator or radio transmitter that
uses either vacuum tube or a transistor to deliver a high-frequency
electric current of at least 1 MHz.
• It is also called surgical diathermy.
FIGURE 26-3 Electrosurgical electrode used to enlarge
• Removal of inflamed or irritated tissues proliferating over the
cervical margin to be prepared.
• In situations, where retraction cord use is not feasible.
• Patients with cardiac pacemaker
• Use of topical anaesthetics (e.g. ethyl chloride or other flammable
• It can be done in irritated or inflamed tissues.
• It results in less or no bleeding.
• It is a sensitive technique.
• It is difficult to control lateral heat dissipation in this technique.
• It cannot be done in dry field.
• Foul smell during the procedure may be unpleasant for the patient.
Commonly used electrosurgical electrodes:
• Profound anaesthesia is given before beginning the procedure.
• All the connections are checked and the cutting tip should be
completely seated into the handpiece.
• Cutting electrode is applied onto the tissues with a quick stroke by
• Speed of the electrode should not be more than 7 mm/s in order to
• The tissues should always be kept moist for best results.
• High-volume suction is kept adjacent to the cutting electrode to
ward off any unpleasant odour.
• A plastic-handled mouth mirror and wooden tongue depressor
• The tip of the electrode should be frequently cleaned with alcoholsoaked sponge.
Electrosurgery is commonly employed for gingival sulcus
enlargement, removal of edentulous cuff and crown lengthening
Techniques used for gingival retraction
There are different techniques which are used for gingival retraction.
Retraction cord impregnated with a medicament is common to all
these techniques. Operator’s choice and clinical situation are
important in deciding the type of technique to be used.
Common techniques for gingival retraction are:
• This is the most commonly used method of gingival retraction.
• It is indicated when impression is made of one to three prepared
• Approximate length of the retraction cord is selected depending on
the anatomy of the prepared tooth.
• The retraction cord is moistened with medicament of choice and is
placed on the prepared tooth with the help of cord packer.
• Cord is allowed into the sulcus for around 8–10 min before it is
• Usually, the cord is soaked with water before it is removed.
• Tooth preparation is dried and impression is made with material of
FIGURE 26-4 Single cord technique.
• It is used during impression making of multiple prepared teeth or
when tissue health is compromised.
• Small diameter cord is placed in the sulcus such that the cut ends
meet each other. This cord is left in the sulcus during impression
• Second cord of largest diameter is soaked in haemostatic agent of
choice and placed over the small cord into the sulcus (Fig. 26-5).
• After 8–10 min, the larger cord is removed.
• Prepared tooth is dried and the impression is made with small cord
• After impression making, the small cord is soaked in water and
FIGURE 26-5 Double cord technique.
• Dento-infusor with 20% of ferric sulphate chemical is commonly
used to control the haemorrhage during cervical margin
• The dento-infusor or syringe is effective in extruding the chemical
• When haemorrhage is controlled a knitted retraction cord is soaked
in ferric sulphate solution and placed into the sulcus.
• The cord is left in place for only 1–3 min.
• After this, the cord is removed, sulcus is rinsed with water, the
prepared tooth is dried and the impression is made.
• The time provided for the cord to stay in sulcus may not be
sufficient to allow adequate lateral displacement of the sulcus.
• Also, ferric sulphate may temporarily darken the gingival sulcus for
Recently introduced materials in the form of synthetic polymers are
injected into the undisplaced sulcus. The material expands and
provides displacement and haemostasis. The efficacy of such
Importance of impression making in fixed partial
An accurate impression is of utmost importance for fabricating a
precisely fitting restoration. Most of the restorations in fixed partial
denture are made by indirect method on the cast in the laboratory.
This saves a lot of chairside time and is comfortable for both the
clinician and the patient. As the restoration is fabricated on the
working model, handling of impression material till the time it is
poured with gypsum product is important. Also, use of proper
technique is essential for achieving an accurate impression. There are
a number of impression materials available from which the clinician
has to choose an appropriate material.
Properties of ideal impression
• Should be dimensionally stable
• Should reproduce accurate detail
• Should adequately wet the oral tissues
• Should have sufficient elasticity after cure so as to facilitate multiple
Ideal requirements of impression material
• Should have an excellent shelf life
• Should have pleasant taste, odour and colour
• Should be easy to manipulate requiring less equipment
• Should have sufficient tear strength
• Should permit multiple pour without distortion
• Should have sufficient working, mixing and setting time
• Should be easily removed from the mouth after setting
• Should have adequate flow to record minute details
Various impression techniques used in fixed
There are a number of impression techniques which can be used by
the clinician to make impression for fixed restorations. Selection of a
particular technique depends on factors such as time, accuracy, cost
and clinical acumen of the clinician.
Impression techniques can be classified on the basis of type of
(i) Stock trays/putty wash impression technique
(iii) Dual arch or closed bite or triple tray impression technique
(iv) Segmental impression technique
(v) Post-space impression technique
Stock tray/putty wash impression technique
There are three methods of making a putty wash impression with
• Metal stock trays are rigid and do not distort easily.
• Stock trays are readily available.
• It saves extra cost of fabricating custom trays.
• There is a need for sterilization of trays.
• More impression material is required.
• In this technique, a putty material is used to make a custom tray.
• First, one layer of wax is placed over the primary cast as a spacer,
removing wax from the nonfunctional cusp region which acts as
• Putty impression material is loaded on the stock tray and placed
over the wax spacer on the primary cast.
• This results in a putty custom tray.
• Wax spacer is then removed and the prepared teeth are injected
with light body elastomer and putty custom tray.
• This loaded tray is then used to make complete arch impression.
• This technique is considered to be most acceptable (Fig. 26-6).
FIGURE 26-6 Impression technique in which putty material is
• This is a two-step technique.
• In the first step, preoperative putty impression is made intraorally.
• A plastic sheet is placed over the teeth to be prepared to act as
• After the complete polymerization of putty material, the plastic
sheet is removed and putty material is removed over the teeth to be
• The second step is done after the completion of tooth preparation;
the putty impression is then washed or relined with low-viscosity
FIGURE 26-7 Two-step impression technique.
• It is difficult to control wash impression material in the relieved
• As the impression material flows into the unrelieved areas, it creates
a problem of hydraulic distortion of the putty material as it is seated
• This is a single-step technique, also called squash or simultaneous
• Here, stock tray is loaded with putty material and the low-viscosity
elastomer is injected around the prepared tooth or teeth
• Tray with putty material is placed over the prepared teeth.
• Impression is made once, both the putty and syringed materials
• This approach should not be used, as it is not possible to control the
thickness and bulk of the impression material used.
• It is impossible to control the flow of either material onto the
• Usually, putty material displaces the low-viscosity material and
• Putty material lacks ability to accurately record details of the margin
FIGURE 26-8 Single-step impression technique.
• Impression material used is less in comparison to stock trays.
• Hygienic, as it is custom-made for particular patient.
• Uniformity of thickness of impression material decreases the
• It is time-consuming during fabrication.
• It cannot be used in patients sensitive to monomer.
• When impression is made of distal most tooth in the arch.
• Where arch does not conform to the dimensions of a stock tray.
• This is a single-step technique.
• On the diagnostic cast, two sheets of baseplate wax are adapted over
• After applying tin foil substitute over the cast, acrylic resin special
tray is fabricated with acrylic resin on the diagnostic cast.
• Vents may be given on the tray to allow easy escape of excess
• Tray adhesive is applied over the internal surface of the special tray.
• Medium body elastomer is loaded onto the tray.
• Low-viscosity elastomer is syringed over the prepared teeth.
• Loaded tray is then seated over the teeth to make complete arch
• The impression is removed after it is polymerized and evaluated.
Dual arch or triple tray or closed bite impression
• Less impression material is needed as only one section of the arch is
• Both the arches are recorded simultaneously.
• Teeth are recorded in maximum intercuspation position.
• There may be less chance of gagging.
• It eliminates any mandibular flexure that may occur during
• As the trays are not rigid, distortion of impression may occur.
• Sometimes buccolingual width of the arch is wider than the tray.
• It should be used in patients with existing anterior guidance.
• It should be used in patients who can completely close in maximum
• It should be used for a maximum of two prepared teeth.
• There should be unprepared teeth (vertical stops), both anterior and
posterior to the prepared teeth.
• Patients with rapidly ascending ramus
• Excessive soft tissues posterior to the last molar
• Fit of the tray is evaluated and the patient is instructed to bite the
tray. The occlusion on the opposing arch is checked using Mylar
• Mix a low-viscosity elastomer and load it in a syringe.
• Then high-viscosity elastomer is mixed and loaded onto the tray.
• The syringe material is injected onto the prepared tooth.
• The patient is asked to bite in maximum intercuspation position.
• Once the material is set, the patient is asked to open the mouth
• Impression is then evaluated.
Segmental impression technique
• It is indicated in cases where simultaneous impression is made of
• It is indicated in patients where moisture control is difficult.
• Impression of the arch with multiple prepared teeth is made in
• Individualized custom trays are fabricated for each segment with
acrylic resin over the diagnostic cast.
• All the segmented trays should be able to seat on the cast
• Tray adhesive is applied on each segmented tray on the internal
• Automix polyvinyl siloxane is loaded onto the tray and seated on
• Once the material is set, the tray is not removed and another
segment is loaded and seated over that segment.
• Procedure is repeated till impression of all the segment is made.
• Then an oversized stock tray is used to make a pick up impression
• The completed impression is evaluated and poured.
Post-space impression technique
• Electrosurgical procedure for impression making is contraindicated
• Epinephrine should be avoided in patients suffering from
hypertension or cardiovascular disease, as it increases the heart rate
• Rubber dam should not be used when impression is made with
polyvinyl siloxane, as it inhibits the polymerization of the
• Svedopter is usually used in mandibular arch when the patient is
seated in nearly upright position.
Provisional Restoration—an Excellent
Commonly Used Resin-Based Materials in
Fabricating Provisional Restorations, 387
Techniques Used for Fabrication of Provisional
Commonly Available Prefabricated
Limitations of Provisional Restoration, 392
Provisional restoration refers to a type of restoration that is provided
to maintain the health of the prepared tooth until definitive or
permanent restoration is given. It is fabricated after the tooth
preparation and is cemented in the same appointment.
Provisional restoration is defined as ‘a fixed or removable dental
prosthesis, or maxillofacial prosthesis, designed to enhance aesthetics,
stabilization and/or function for a limited period of time, after which it is to
be replaced by a definitive dental or maxillofacial prosthesis. Such prosthesis
is used to assist in determination of the therapeutic ef ectiveness of a specific
treatment plan or the form and function of the planned definitive prosthesis’.
An ideal restoration should meet certain requirements necessary for
successful treatment. These requirements can be grouped into three
categories, namely, biological, mechanical and aesthetic.
• It should seal and provide insulation to the prepared tooth to avoid
• It should have a good marginal fit to prevent plaque accumulation
• It should have a smooth surface and proper contour to permit easy
• It should not impinge on the gingival tissues and should be
• It should have proper contact with the opposing tooth so as to avoid
• It should have adequate proximal contact with the adjacent teeth so
as to avoid drifting or horizontal movement.
• It should protect the prepared margins of the tooth to prevent
• It should not have overextended or underextended contours to
• It should have appropriate pontic, in order to maintain proper
gingival health and aesthetic contours.
• It should have adequate strength to withstand the functional forces
of chewing without fracturing.
• It should adapt well to the prepared tooth to avoid movement or
• It should remain intact on its removal so that it may be reused.
• It should establish proper occlusal and proximal contacts.
• Anterior provisional restoration should have proper lateral and
• It should satisfy the aesthetic need of the patient, especially in the
• It should be made of biocompatible material which is easily
• It should be translucent and colour compatible with adjacent
Provisional restoration—an excellent diagnostic
Provisional restoration or interim restorations are an excellent
diagnostic tool used in fixed prosthodontics. Provisional restoration
serves as guide to determine whether the planned restoration satisfies
the functional, physiological or aesthetic requirement or not. Once the
diagnostic wax-up is done after completing the mock preparation on
the cast, the provisional restorations are fabricated with appropriate
material. This restoration helps in determining whether the proposed
treatment will satisfy the functional and aesthetic need of the patient
or not. The importance of provisional restoration in diagnosis is
magnified with the increase in complexity of the fixed treatment.
• Determining the changes in centric occlusion and incisal guidance.
• Determining the changes in vertical dimension.
• Determining the changes in occlusal or incisal plane, tooth length or
• Aiding the diagnosis and treatment planning of periodontally
• Aiding the preprosthetic, endodontic and orthodontic procedures.
• Serving as an excellent guide in procedures such as crown
lengthening, ridge augmentation and pontic site preparation.
• Serving as a guide for the laboratory technician to fabricate the
Provisional restoration, therefore, proves to be a valuable diagnostic
tool which provides a blueprint for a predictable, functional and
durable definitive prosthesis.
Commonly used resin-based materials in
fabricating provisional restorations
The most common materials used for fabricating single or multiple
unit provisional restorations are resin-based materials. There are a
number of resin-based materials which are available in the market.
The basic properties of these resins are similar to each other but only
differ in filler composition, type of monomer and method of
The commonly used resin materials for fabricating provisional
• Poly(methyl methacrylate) (PMMA)
• Visible light-cured (VLC) dimethacrylate
Type of Resin Material Advantages Disadvantages
PMMA (poly[methyl methacrylate])Most
commonly used resin for provisional
Polyethyl methacrylate • Can be highly polished
Bis-acryl composite • High modulus of rupture
• Low exothermic heat increase
VLC urethane dimethacrylate • Less polymerization
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