DONE BY; SANDEEP
RAJA.N,RICHARDSON PATRICK.S
CRI
INTRODUCTION
• THE ANATOMY OF EDENTULOUS RIDGES IN THE
MAXILLA AND MANDIBLE IS VERY IMPORTANT FOR THE
DESIGN OF THE COMPLETE DENTURE
• THE TOTAL AREA OF SUPPORT FROM THE MANDIBLE
IS SIGNIFICANTLY LESS THAN FROM THE MAXILLA.
• THE AVERAGE AVAILABLE DENTURE BEARING AREA FOR
AN EDENTULOUS MANDIBLE IS 14cm2 , WHEREAS FOR
EDENTULOS MAXILLA IT IS 24cm2. THEREFORE THE
MANDIBLE IS LESS CAPABLE OF RESISTING OCCLUSAL
FORCES THAN THE MAXILLA.
• THE CONSISTENCY OF THE MUCOSA AND THE UNDERLYING
BONE IS DIFFERENT IN VARIOUS PARTS OF THE EDENTULOUS
RIDGE
• SOME PARTS OF THE RIDGE ARE CAPABLE OF
WITHSTANDING MORE FORCE THAN OTHER AREARS
LIMITING STRUCTURES
SUPPORTING STRUCTURES
RELIEF AREAS
LABIAL FRENUM
LABIAL VESTIBULE
BUCCAL FRENUM
BUCCAL VESTIBULE
HAMULAR NOTCH
POSTERIOR PALATAL SEAL AREA
FOLD OF MUCOUS
MEMBRANE
NO MUSCLE
NO ACTION OF
ITS OWN
A “V” SHAPED NOTCH
SHOULD BE RECORDED
DURING IMPRESSION
MAKING
LABIAL NOTCH OF THE
LABIAL FLANGE OF THE
DENTURE MUST BE JUST
WIDE ENOUGH AND JUST
DEEP ENOUGH TO
ACCOMMODATE THE
LABIAL FRENUM
IT IS DIVIDED LEFT AND
RIGHT BY THE LABIAL
FRENUM
ORBICULARIS ORIS IS THE
MAIN MUSCLE WHICH
FORMS THE OUTER
SURFACE OF THE LABIAL
VESTIBULE
ORBICULARIS ORIS
MUSCLE HAS ONLY AN
INDIRECT EFFECT ON THE
LABIAL VESTIBULE
BECAUSE ITS FIBERS RUN
IN HORIZONTAL
DIRECTION
DIVIDING LINE BETWEEN
THE LABIAL AND BUCCAL
VESTIBULE.
FRENUM MAY BE SINGLE
OR DOUBLE.
LEVETOR ANGULI ORIS
MUSCLE ATTACHES
BENEATH THE FRENUM.
ORBICULARIS MUSCLE
PULLS THE FRENUM
FORWARD.
BUCCINATOR MUSCLE
PULLS IT BACKWARD.
REQUIRE MORE
CLEARENCE FOR ITS
ACTION
EXTEND FROM BUCCAL
FRENUM TO HAMULAR
NOTCH
BOUNDED LATERALLY BY
THE CHEEKS AND
MEDIALLY BY THE
RIDGE.
SIZE OF THE VESTIBULE
VARIES WITH THE
CNTRACTION OF
BUCCINATOR MUSCLE,
POSITION OF THE
MANDIBLE, AND AMOUNT
OF BONE LOST FROM
MAXILLA.
ADEQUATE DEPTH/WIDTH
SHOULD BE RECORDED
DISTAL LIMIT OF THE
BUCCAL VESTINULE.
SITUATED BETWEEN THE
TUBROSITY AND
HAMULUS OF THE MEDIAL
PTERYGOID BONE.
TENSOR VELI PALATINI
MUSCLE RUNS
HORIZONTALLY
THROUGH THIS NOTCH.
AIDS IN ACHIEVING
POSTERIOR PALATAL
SEAL.
“THE SOFT TISSUE AT OR ALONG THE JUNCTION OF THE HARD
AND SOFT PALATE ON WHICH PRESSURE WITHIN THE
PHYSIOLOGICAL LIMITS OF THE TISSUE S CAN BE APPLIED BY
A DENTURE TO AID IN THE RETENSION OF THE DENTURE”
-GPT.
PARTS:
•POSTPALATAL SEAL
•PTERYGOMAXILLARY SEAL
EXTENSIONS:
•ANTERIORLY- ANTERIOR VIBRATING LINE
•POSTERIORLY- POSTERIOR VIBRATING LINE
•LATERALLY- 3-4 MM ANTERIOLATERAL TO
HAMULAR NOTCH
“THE IMAGINARY LINE ACROSS THE POSTERIOR PART OF
THE PALATE MAKING THE DIVISION BETWEEN THE
MOVABLE AND IMMOVABLE TISSUES OF THE SOFT
PALATE WHICH CAN BE IDENTIFIED WHEN THE
MOVABLE TISSUES ARE MOVING”-GPT
Anterior &Posterior
Vibrating line
PRIMARY STRESS SECONDRY STRESS
BEARING AREA BEARING AREA
HARD
PALATE RESIDUAL
MAXILLARY ALVEOLAR RIDGE
TUBEROSITY
COVERED BY KERATINIZED SQUAMOUS
EPITHELIUM.
ANTERIOLATERALLY, THE SUBMUCOSA
CONTAINS ADIPOSE TISSUE.
POSTEROLATERALLY IT CONTAINS
GLANDULAR TISSUE.
THE HORIZONTAL PORTION OF THE
HARD PALATE PROVIDES THE PRIMARY
STRESS-BEARING AREA
IT IS THE POSTERIOR
CONVEXITY OF THE
MAXILLARY BODY.
THE MEDIAL AND
LATERAL WALLS RESIST
THE HORIZONTAL
AND TORQUING
FORCES WHICH
WOULD MOVE THE
DENTURE BASE IN
LATERAL OR PALATAL
DIRECTION.
THEREFORE MAXILLARY
DENTURE BASE SHOULD
COVER THE TUBEROSITY
AND FILL THE HAMULAR
NOTCHES.
COVERED BY KERATINIZED SRATIFIED
SQUAMOUS EPITHELIUM.
THE SUB MUCOSA IS CHARECTERIZED BY DENSE
COLLAGENOUS FIBERS THAT ARE CONTIGUOUS
WITH LAMINA PROPRIA
CONSIDERED AS A SECONDRY STRESS BEARING
AREA BECAUSE IT IS SUBJECTED TO RESORPTION
TO HORIZONTAL PORTION OF HARD PALATE
INCISIVE PAPILLA
MEDIAN PALATAL RAPHE
FOVEA PALATINE
SITUATED ON A LINE
IMMEDIATELY BEHIND
AND BETWEEN THE
CENTRAL INCISORS
THE INCISIVE FORAMEN IS
LOCATED BENEATH THE
INCISIVE PAPILLA.
LOCATION OF THE INCISIVE
PAPILLA GIVES AN
INDICATION AS TO THE
AMOUNT OF RESORPTION
THAT HAS TAKEN PLACE.
THE NASOPALATINE
NERVES AND VESSELS PASS
THROUGH THE INCISIVE
FORAMEN.
THE SUBMUCOSA IS
EXTREMELY THIN IN THE
REGION OF MEDIAL
PALATAL SUTURE, SO THE
MUCOSAL LAYER IS IN
CLOSE CONTACT WITH THE
UNDERLYING BONE.
FOR THIS REGION, THE SOFT
TISSUE COVERING THE
MEDIAN PALATAL TISSUE IS
NONRESILIENT IN NATURE
& MAY NEED TO BE
RELIEVED.
BILATERAL
INDENTATION NEAR THE
MIDLINE OF PALATE
FORMED BY COALESCENCE
OF SEVERAL MUCOSAL
GLAND DUCT
POSTERIOR TO JUNCTION OF
HARD AND SOFT PALATE
ALWAYS ON SOFT PALATE
LIMITING STRUCTURES
SUPPORTING STRUCTURES
RELIEF AREAS
Labial frenum
Labial vestibule
Buccal frenum
Buccal vestibule
Lingual frenum
Alveolingual sulcus
Retromolar pad
Pterygomandibular raphe
It is a fold of mucous
membrane at the median
line.
It divids the labial
vestibule into left and
right labial vestibule
Recorded as a notch in
the impression made
Frenum contains
fiber of Orbicularis
oris and Mentalis
muscle
Therefore the
frenum is quite
sensitive and active,
and the denture
must be fitted
carefully around it
to maintain a seal
without causing
soreness
The labial vestibule
extend from the
labial frenum to the
buccal frenum
Muscle attachment
close to the crest of
the ridge –limits the
denture flange
extension
The buccal frenum
forms the
dividing line
between the labial
and buccal
vestibule.
It overlies the
depressor anguli oris
muscle.
Fibers of buccinator
muscle attached to
the frenum.
Frenum may be
single or double,
broad U shaped or
sharp V shaped.
It should be relieved
to prevent
displacement of the
denture during
function.
Extend from buccal
frenum to retromolar
pad
The extent of buccal
vestibule is influenced
by the buccinator
muscle,
which extends from the
modiolus anteriorly to
the pterygomandibular
raphe posteriorly
The impression is widest
in this region.
Fold of mucous
membrane.
•Base of tongue to
supragenial tubercle.
The anterior region of
the lingual flange is
called sub-lingual
crescent area
A high frenum is
called as Tongue tie.it
should be corrected
if it affects the
stability of the
denture.
Space between the
residual ridge & tongue .
Extends from lingual
frenum to retromylohyoid
curtain .
3 regions (anterior,
middle & posterior)
The anterior region
extends from the lingual f.
back to where mylohyoid
muscle curves above the
level of the sulcus
(premylohyoid fossa) .
The middle region extends from
premylohyoid fossa to the distal
end of the mylohyoid ridge,
curving medially from the body
of the mandible. This curvature is
caused by the prominance of
mylohyoid ridge & the action of
mylohyoid muscle.
The posterior region: here the
flange passes into the
retromylohyoid fossa &
completes the typical S form of
the correctly shaped lingual
flange.
The retromylohyoid
space lies at the distal
end of the
alveololingual sulcus.
Bounded by
Anterior tonsillar
pillar,posteriorly by
the retromylohyoid
curtain.
Formed
posteriorly by
the superior
constrictor muscle,
Laterally by the
mandible &
pterygomandibular
raphe,
Anteriorly by lingual
tuberosity, and
Inferiorly by the
mylohyoid muscle.
The retromolar pad is a
pear shaped area
containing glandular
tissue, loose areolar
connective tissue,the
lower margin of the
pterygomandibular
raphe,fibers of
buccinator and superior
constrictor, along with
the fibers of temporal
tendon.
The retromolar papilla is a pear shaped area just
anterior to the retromolar pad, it is dense, fibrous
connective tissue.
Buccal shelf area
Residual alveolar ridge
Extend from the buccal
frenum to the anterior
edge of the masseter
muscle.
Boundries :
Medially- crest of the ridge
Laterally- external oblique
ridge.
Distally –retromolar pad
The mucous membrane
covering the buccal
shelf area is loosely
attached, less
keratinized & contains
thick submucosal layer.
Considered as a
primary stress-bearing
area because it is
covered by a layer of
cortical bone, & it lies at
right angles to vertical
occlusal forces
The crest of the
residual alveolar
ridge is covered by
fibrous connective
tissue,
But in many mouths
the underlying
bone is cancellous
and without a good
cortical bony plate
covering it.
The mucous membrane covering the crest of the
residual ridge is covered by keratinized layer
and is attached by its submucosa to the
periosteum of the mandible.
The extent of this attachment varies
considerably. In some people, the submucosa is
loosely attached to the bone over the entire
crest of the residual ridge, and the soft tissue is
quite movable.
In others, the submucosa is firmly attached to
the bone on both the crest and the slopes of the
lower residual ridge.
However, because underlying bone is often
cancellous (bony spicules and nutrient canals),
the crest of the residual ridge may not be
favorable as the primary stress-bearing area for
a lower denture.
Mental foramen
Genial tubercle
Mylohyoid ridge
Mandibular tori.
As resorption takes place,
the mental foramen will
come to lie closer to the
crest of ridge.
In these circumstances, the
mental nerve and blood
vessels may be compressed
by denture base unless relief
is provided.
Pressure on mental nerve
can cause numbness of
lower lip.
The genial tubercle are a
pair of dense
prominences at the
inferior border of the
mandible at the lingual
midline.
They represents the
muscle attachment of
the genioglossus
and geniohyoid
muscle.
They only become
relevant in the denture
when there is
excessive resorption of
the residual ridge.
The mylohyoid ridge is a boney
prominence along the lingual
aspect of the mandible
Soft tissue usually hides the
sharpness of mylohyoid ridge.
Anteriorly, this ridge with
mylohyoid muscle is close to
inferior surface of mandible.
Posteriorly, after resorption, it
often flushes with the residual
ridge.
The mucous
overlying the sharp or irregular
membrane
mylohyoid ridge needs to be
relieved.
Mandibular tori are
lingual bilateral
prominences of
cortical bone in the
premolar area.but they
may extend
posteriorly to the
molar area.
small tori may
only require relief
in the denture.
Large tori reguire
removal before a
denture can be
fabricated
