Download - ACKNOWLEDGEMENT dr shabeel pn
ACKNOWLEDGEMENT dr shabeel pn 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 ANATOMICALLANDMARKS FACIALMUSCLES
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 ZYGOMATICUSMAJOR LEVATORANGULIORIS RISORIUS
DEPRESSORANGULIORIS MUSCLEORIGINATINGFROMTHEMODIOLUS
ORBICULARISORIS SPINTUREMUSCLEOFTHEORALFISSURE DIALATOR MUSCLES OF
THE MOUTH
LEVATORLABII SUPERIORES LEVATORANGULIORIS ZYGIOMATICUSMAJOR
ZYGOMATICUSMINOR DEPRESSORLABIIINFERIORIS DEPRESSORANGULIORIS
RISORIUS PALATE MUSCLES OF PALATE LEVATOR VELI PALATINI TENSOR VELI
PALATINI
PALATOGLOSSUS PALATOPHARYNGEUS MUSCULUSUVULAE TENSOR VELI PALATINI
SUPERIOR ATACHMENT
Scaphoid fossa of medial pterygoid plate Spine of sphenoid bone
Cartilage of pharyngo tympanic tube INFERIORATACHMENT 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
INFERIORATTACHMENT 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
LABIALFRENUM BUCCALFRENUM LABIAL VESTIBULE BUCCALVESTIBULE
HAMULARNOTCH 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
SIGNIFICANCE
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 frenumthrough itwithout
manipulation of the lip. BUCCDAL FRENUM RELATION WITH FACIAL
MUSCLES SIGNIFICANCE
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 RELATIONWITHFACIALMUSCLES 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 SIGNIFICANCE
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 thebuccal frenum in the buccal notch LABIAL VESTIBULE
RELATION WTH FACIAL MUSCLES
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 RELATIONWTHFACIALMUSCLES
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
BUCCALVESTIBULE 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 HAMULARNOTCH 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 VIBRATINGLINE 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
FOVEAPALATINAE (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) FINALIMPRESSION 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 IDEALREQUIREMENTS 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
FABRICATIONOFCUSTOMTRAYHANDLE 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
Available in 3 viscosities
MODEOFSUPPLY Base and catalyst in paste form Available in 3
viscosities Light body Medium body Heavy body COMPOSITION BASE
PASTE ACCELERATOR PASTE Alkyl aromatic sulphonate
Polyether polymer Colloidal silica (filler) Glycoether/Phthalate
(plasticizer) ACCELERATORPASTE Alkyl aromatic sulphonate (cross
linkingagent) Colloidal silica (filler) Glycoether/Pthalate
(plasticizer) SETTINGREACTION 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
sulphonateester 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
BRANDNAMES 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 extend2 mm
posterior to the vibrating line Vibrating line can be demonstrated
by 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 toproper 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 highmodulus of elasticity Absorbs
water Leaches components Corrections cannot be made Expensive
FINALPROCEDURES 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.