ACKNOWLEDGEMENT
We express our deep and sincere
gratitude to whom who has
been our inspiration for this
presentation.
DEFINITION
• Border molding is the shaping of an impression material by the
manipulation or action of tissues adjacent to the borders of an
impression tray
OBJECTIVE
• To determine the contour, height and width of the borders of
the complete denture
ANATOMICAL LANDMARKS
Limiting structures:• Labial frenum
• Labial vestibule
• Buccal frenum
• Buccal vestibule
• Vibrating line
CUSTOM TRAY FABRICATION
•
Preliminary impression is taken using stock trays
•
Primary cast is obtained with this impression
•
Wax spacer used, if required
•
Custom tray is fabricated (stepped handle for
maxillary arch)
MATERIALS USED FOR BORDER
MOLDING
• GREEN STICK COMPOUND
• ELASTOMERIC IMPRESSION MATERIALS
(POLYETHER)
BORDER MOLDING TECHNIQUE
• GREEN STICK COMPOUND - SECTION WISE
TECHNIQUE
• POLY ETHER - SINGLE STEP TECHNIQUE
FINAL PROCEDURES
• FINAL ADJUSTMENTS OF REFINED TRAY
• PERFORATION OF THE TRAY
ANATOMICAL LANDMARKS
FACIAL MUSCLES
ORBICULARIS ORIS – Oral Sphincter
ORIGIN
•Medial maxilla and mandible
•Deep surface of perioral skin
•Angle of mouth (modiolus)
INSERTION
•Mucous membrane of lip
ACTION
•Contraction of the muscle protrudes lip or resists distension
BUCCINATOR - Cheek muscle
ORIGIN
• Alveolar process of maxilla and mandible
• Pterygomandibular raphae
INSERTION
• Angle of mouth (Modiolus)
• Orbicularis oris
ACTION
• Presses cheek against molar teeth with tongue
• Helps to keep food material between occlusal surface and out of the oral
vestibule
• Resists distension (while blowing)
LEVATOR ANGULI ORIS
ORIGIN
• Infraorbital maxilla (Canine Fossa)
INSERTION
• Angle of mouth (Modiolus)
ACTION
• Dilator of mouth
• Elevate labial commissure - Bilaterally while smiling
Unilaterally while sneering
MUSCLES WITH ATTACHMENT TO THE
MODIOLUS
• BUCCINATOR
• ZYGOMATICUS MAJOR
• LEVATOR ANGULI ORIS
• RISORIUS
• DEPRESSOR ANGULI ORIS
MUSCLE ORIGINATING FROM THE MODIOLUS
ORBICULARIS ORIS
SPINTURE MUSCLE OF THE ORAL FISSURE
ORBICULARIS ORIS
DIALATOR MUSCLES OF THE MOUTH
• LEVATOR LABII SUPERIORES
• LEVATOR ANGULI ORIS
• ZYGIOMATICUS MAJOR
• ZYGOMATICUS MINOR
• DEPRESSOR LABII INFERIORIS
• DEPRESSOR ANGULI ORIS
• RISORIUS
PALATE
MUSCLES OF PALATE
• LEVATOR VELI PALATINI
• TENSOR VELI PALATINI
• PALATOGLOSSUS
• PALATOPHARYNGEUS
• MUSCULUS UVULAE
TENSOR VELI PALATINI
SUPERIOR ATACHMENT
• Scaphoid fossa of medial pterygoid plate
• Spine of sphenoid bone
• Cartilage of pharyngo tympanic tube
INFERIOR ATACHMENT
• Palatine aponeurosis
ACTION
• Tenses soft palate
• Opens mouth of pharyngotympanic tube during swallowing and
yarning
LEVATOR VELI PALATINI
SUPERIOR ATTACHMENT
• Cartilage of pharyngotympanic tube
• Petrous temporal bone
INFERIOR ATTACHMENT
• Palatine aponeurosis
ACTION
• Elevates soft palate during swallowing and yarning
PALATOGLOSSUS
SUPERIOR ATTACHMENT
• Palatine aponeurosis
INFERIOR ATTACHMENT
• Side of tongue
ACTION
• Elevates posterior part of tongue and draws soft palate into tongue
PALATOPHARYNGEUS
SUPERIOR ATTACHMENT
• Hard palate and palatine aponeurosis
INFERIOR ATTACHMENT
• Lateral wall of pharynx
ACTION
• Tenses soft palate and pulls walls of pharynx superiorly, anteriorly
and medially during swallowing
MUSCULUS UVULAE
SUPERIOR ATTACHMENT
• Posterior nasal spine and palatine aponeurosis
INFERIOR ATTACHMENT
• Mucosa of uvula
ACTION
• Shortens uvula and pulls it superiorly
LIMITING STRUCTURES OF
EDENTULOUS MAXILLARY ARCH
• LABIAL FRENUM
• BUCCAL FRENUM
• LABIAL VESTIBULE
• BUCCAL VESTIBULE
• HAMULAR NOTCH
• VIBRATING LINE
LABIAL FRENUM
•It is a fold of mucous membrane at the
median line.
•It starts superiorly in a fan shape and
converges as it descends to its terminal
attachment on the labial side of the ridge.
•It contains no muscles and has no action
of its own.
LABIAL NOTCH
• Corresponding area of labial frenum on the final impression
SIGNIFICANCE
• The labial notch of the labial flange of denture must be wide and deep
enough to allow the frenum through it without manipulation of the lip.
BUCCDAL FRENUM
• It forms the dividing line between labial
vestibule and buccal vestibule
• It is formed by mucous membrane
• Can be a single fold, double fold and
even fan shaped
RELATION WITH FACIAL
MUSCLES
• Levator Anguli Oris muscle attaches
beneath the frenum
• Orbicularis oris pulls the frenum
forward
• Buccinator pulls the frenum backward
SIGNIFICANCE
• It requires more clearance in the denture
base for its movements than the labial
frenum
BUCCAL NOTCH
• It is the impression made by the buccal frenum on the impression
• It should be wide and deep enough to permit the movements of the buccal
frenum
SIGNIFICANCE
• While making impression, lips should be moved forward and backward by
the dentist to allow the free movement of the buccal frenum in the buccal
notch
LABIAL VESTIBULE
• Labial vestibule is divided into left and
right labial vestibule by the labial frenum
• Mucosa is thin and NONKERATINIZED
• Submucosa is thick and contains large
amount of areolar tissue and elastic fibers
• Lamina propria is elastic in nature
RELATION WTH FACIAL
MUSCLES
• Orbicularis oris is the main muscle which
forms the outer surface of the labial
vestibule
• The fibers of this muscle runs horizontally
through the lips to anastamose with the
muscles of the Buccinator
BUCCAL VESTIBULE
• It is the space distal to the buccal frenum
till the hamular notch
• It is bound externally by the cheek and
internally by the residual ridge
• Mucous membrane covering is similar to
labial vestibule
The size of the vestibule varies with
• contraction of the Buccinator M.
• position of the mandible
• amount of bone lost by resorption from the
maxilla
HAMULAR NOTCH
• Region between the tuberosity of the
maxilla and the hamulus of the medial
pterygoid plate
SIGNIFICANCE
• Posterior palatal seal is placed through the
centre of the deepest part of hamular notch
• Forms the posterior boundary for the
denture base
• If the posterior border extend further in this
region, the denture base will compress the
pterygoid hamulus and obstruct the action
of the pterygomandibular raphae
VIBRATING LINE
• It is the imaginary line drawn across the palate that marks the beginning of
motion of the soft palate when patient is asked to exhale through his/her
nose with the nostrils closed
• Extends from one hamular notch to the other
• Lies distal to the junction of the hard and soft palate – lies always on the
soft palate
• At the midline, it passes about 2mm in front of the FOVEA PALATINAE
(indentations near the midline of the palate formed by a coalescence of
several mucous gland ducts)
• It is not a well defined line – but an area
• Submucosa in this region contains glandular tissue
SIGNIFICANCE
• It is an ideal guide for locating the posterior palatal seat area (the distal
palatal termination of the denture) during BORDER MOLDING
• The distal end of the maxillary denture should extend at least to the
vibrating line (in most cases 1 to 2 mm posterior to the vibrating line)
FINAL IMPRESSION
• After the primary impression is taken and a cast made from it,
the procedure for final impression begins
• A carefully made special tray is trimmed at the corners and
border molding is done followed by a wash impression and
pouring in the cast completes the procedure. In a nutshell, final
impression involves special tray preparation and wash
impression
MATERIALS
• Metallic Oxide Impression Paste
(Ex. ZOE Impression Paste)
• Elastomeric Impression Materials
ZINC OXIDE EUGENOL
IMPRESSION PASTE
INDICATIONS
• These pastes are rigid when set and can be used only when
there is no bony undercuts
• Used in a close fitting tray and so the overall bulk of
impression is kept to a minimum. This is useful where the
denture bearing area is reduced due to bone resorption
CONTRAINDICATIONS
• Not used in patients with dry mouths because the paste tends
to adhere to the oral mucous membrane
• When the patient is intolerant to Eugenol as it can cause a
burning sensation in some individuals
ELASTOMERIC IMPRESSION MATERIALS
• These materials are used in spaced custom trays to avoid
displacement the border tissues
• A less viscous consistency/body of the irreversible
hydrocolloid is used for making final impression compared
with that used for preliminary impression.
CUSTOM TRAY FABRICATION
DEFINITION
• A special tray is defined as a custom made
device prepared for a particular patient which is
used top carry, confine and control an
impression material while making an
impression.
FUNCTION
• To provide better retention of denture
• To take secondary or wash impression
IDEAL REQUIREMENTS
• Should be rigid, well adapted and dimensionally stable on primary cast
• Should be easy to manipulate and remove
• Should not flow or warp
• Should not react with impression material
• Should be free of voids or projections
• Should be at least 2 mm thick in the palatal area for adequate rigidity
• Should be smooth lest it injures the soft tissue inside the mouth
• Should be trimmable with bur
• Should be simple, taking minimum amount of time and should be prepared
at a reasonable cost
• Should have 2 mm relief near the sulcus so that the green stick compound
can be used to do border molding
• Should retain its shape while loading of impression
• Should have contrasting colour to make its margins prominent when placed
in mouth
CONDITIONING THE PRIMARY CAST
• Primary impression has
overextended borders therefore
special tray should be 2 to 4 mm
short of the sulcus
• A line is drawn across the
posterior border connecting the 2
hamular notches (this line is
parallel to fovea palatinus)
• A line is drawn outlining the
muco-buccal fold above the
frenum attachments
• All trays should be checked of
displacement in the mouth
ADAPTING THE WAX SPACER
• Base plate wax, 1 mm thick
approximately is placed on the cast
within the outline border to provide
space in the tray for the final
impression material
• Spacer should be cut out in 2 to 4
places so that the special tray touches
the ridge in these areas. This is done
to stabilize the tray during
impression making.
• The posterior palatal seal area on the
cast is not covered with the wax
spacer therefore the completed
custom tray will contact the mucous
membrane across the posterior
palatal border
APPLICATION OF SEPARATING MEDIUM
• To prevent special tray from binding to the cast
FABRICATION OF CUSTOM TRAY HANDLE
• The custom tray should be 2 to 3 mm thick,
with a stepped handle in the anterior region
of the tray to facilitate removal from the
mouth
• The step should be of sufficient height to
avoid distortion of the upper lip when the
tray is in the mouth
TRIMMING THE CUSTOM TRAY
IDEAL REQUIREMENTS OF MATERIALS
USED FOR BORDER MOLDING
• It should have a sufficient body to allow to remain positioned on the
borders during loading of the tray
• Allow some pre shaping of the form of the borders without adhering to the
finger
• Have a setting time of 3 to 5 minutes
• Retain adequate flow while tray is seated in the mouth
• Allow finger placement of the material into the deficient parts after tray is
seated
• Should not cause excessive displacement of the vestibule
• Readily trimmed and shaped so excess material can be removed and
borders are shaped before final impression is made
GREEN STICK IMPRESSION COMPOUND
• Rigid impression Material
MANIPULATION
• On heating above fusion temperature over a
flame, the material becomes ready for border
molding
• Over heating is avoided as it can volatilize
the plasticizer
• Tempering is done using a water bath which
reduces the temperature to tolerable limits
• The compound becomes rigid at oral
temperature
POLYETHER ELASTOMERIC IMPRESSION
MATERIAL
• Introduced in Germany in late 1960
• It is a polyether based polymer
MODE OF SUPPLY
• Base and catalyst in paste form
Available in 3 viscosities –
• Light body
• Medium body
• Heavy body
COMPOSITION
BASE PASTE
ACCELERATOR PASTE
• Polyether polymer
• Alkyl aromatic sulphonate
(cross linking agent)
• Colloidal silica (filler)
• Colloidal silica (filler)
• Glycoether/Phthalate
(plasticizer)
• Glycoether/Pthalate (plasticizer)
SETTING REACTION
• It is cured by a polymerization reaction between Aziridine rings at the end
of the branched polyether molecule
• The main chain is a copolymer of ethylene oxide and THF
• Cross linking is by initiator called aromatic sulphonate ester with alkyl
group
• The reaction is exothermic
PROPERTIES
• Working time – 3 minutes
• Setting time – 6 minutes
• No byproduct is formed during reaction
• Shelf life – more than 2 years
BRAND NAMES
• Impregum F
• Permadyne
• Polyjel
PROCEDURE FOR BORDER MOLDING
• This is a stepwise procedure which ensures an optimal
peripheral seal
• Firstly, special tray is checked in the patient's mouth for
its adaptability, extension and checked for irregularities
if any that may hurt soft tissue while taking impression
•
Posterior palatal border - tray should include both
hamular notch and extend 2 mm posterior to the
vibrating line
•
Vibrating line can be demonstrated by
1.
2.
When patient says "ah"
When patient's nostril closed and asked to exhale
through nose during which soft palate will flex at
junction
• Posterior border of tray marked with a marker, tray then
place in mouth and patient asked to say "ah"
• Tray removed and mark is transferred into the mouth
which is compared with vibrating line and hamular notch
STEPS IN BORDER MOLDING
• Procedure in which portions of the periphery of the tray
are refined individually
• Greenstick compound is softened over flame and added
along the labial vestibule initially
• Material is tempered before placing intra-orally
• Tray introduced into mouth with lip first elevated, then
extended outward, downward and inward
• Massage the upper lip in lateral motion
• Patient instructed to pucker
• Material is then softened and then placed over buccal
vestibule and tempered
• Tray is seated in oral cavity stabilizing with finger
• At the buccal frenum, cheek is elevated, pulled outward,
downward, inward and moved backward and forward to
simulate movement of frenum
• Posteriorly, buccal flange border molded by extending
cheek outward, downward and inward followed by wide
opening of mouth and side to side movement of
mandible
• Patient asked to pucker for
activation of Buccinator
• Greenstick is flamed, traced along
border from buccal to hamular
notch area across midline to
corresponding area on opposite
side
• Next the posterior palatal area is
recorded to complete an effective
peripheral seal during which
patient is asked to say "ah"
• After border molding, molded section is immersed in
cold water
• Evaluate the retention and stability of the border molded
tray
BORDER MOLDING USING POLYETHER
IMPRESSION MATERIAL
•
Placement of adhesive on the border of
the tray
•
Cutting away the wax spacer from the
border to allow space for the impression
material.
•
Placement of polyether material along the
borders
•
Composition is in such a way that
sufficient working time is to be provided
•
Material is pre shaped to proper contours
•
Placement of tray in the mouth
•
Lips retracted to avoid scraping
of material from the borders
•
If insufficient material is present,
transferring of excess material
from the adjacent site
BORDER MOLDING IN THE ANTERIOR REGION
• Lip elevated and extended out, downward and inward
IN THE BUCCAL FRENUM
• Cheek is elevated and pulled outward, downward and inward and move
backward and forward to stimulate the movement of frenum
POSTERIORLY • Buccal flange is border molded by extending the cheek outward, downward
and inward
• Patient asked to open wide and move mandible side to side
• When impression material is set tray removed from the mouth
• Contour should be rounded and over extensions are readily detected as the
tray will protrude through the polyether material
GREEN STICK COMPOIND
ADVANTAGES
•Corrections can be made
•Less expensive
•Less technique sensitive
•No imbibition and synerisis
DISADVANTAGES
•Poor surface detail
•Time consuming procedure
•More number of tray insertions
•Discomfort to the patient
POLYETHER ELASTOMERIC IMPRESSION
MATERIAL
ADVANTAGES
• Fast setting
• Good stability
• Can delay pouring
• No need for heating the material
• Procedure is completed in one step
• No byproducts are formed during setting
• Shelf life of 2 years
DISADVANTAGE
• Bitter taste
• Stiff – high modulus of elasticity
• Absorbs water
• Leaches components
• Corrections cannot be made
• Expensive
FINAL PROCEDURES
• After border molding, the tray should be
prepared before making the secondary
impression
• Space should be created for final
impression material
• If necessary, the thickness of the border
should be adjusted
• Material that extend into the undercut is
reduced
• Finally, a small amount of material is
removed from those parts of the border
that have not already been adjusted
• Approximately 0.5 mm is removed from the
inner, outer and top surface of the border
• Stick impression compound is adjusted with
a scalpel
• polyether adjusted with a scalpel or a bur
• The material over the posterior area is not
adjusted
• Finally, holes can be placed in the palate of
the impression tray with a medium sized
round bur
• Then the adhesive material is applied
• The objective is to avoid recording denture bearing tissues in a displaced or
distorted position
• A number of materials are available for making the final impression and it
includes metallic oxide impression paste, polyether and silicone impression
materials and irreversible hydrocolloids.