Final anatomic landmarks/ online orthodontic courses

INDIAN DENTAL ACADEMY
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CONTENTS-CONTENTS-
 IntroductionIntroduction
 DefinitionDefinition
 Supporting structuresSupporting structures
1. Bone1. Bone
2.Mucous membrane2.Mucous membrane
 Peripheral or limiting structuresPeripheral or limiting structures

 Anatomy of limiting structures in maxillaryAnatomy of limiting structures in maxillary
regionregion
 Anatomy of supporting structures inAnatomy of supporting structures in
maxillary regionmaxillary region
 Anatomy of limiting structures inAnatomy of limiting structures in
mandibular regionmandibular region
 ConclusionConclusion
 ReferencesReferences

INTRODUCTION-INTRODUCTION-
If dentures and their supporting tissuesIf dentures and their supporting tissues
are to coexist for a reasonable length of time,are to coexist for a reasonable length of time,
the prosthodontist must fully understand thethe prosthodontist must fully understand the
macroscopic and microscopic anatomy ofmacroscopic and microscopic anatomy of
edentulous mouth of the patient.edentulous mouth of the patient.

 Anatomic landmark-Anatomic landmark-
““ a recognizable anatomic structurea recognizable anatomic structure
used as a point of reference.”used as a point of reference.”
GPT-8GPT-8
 In both maxilla and mandible anatomicIn both maxilla and mandible anatomic
landmarks has been divided in-landmarks has been divided in-
-supporting structures-supporting structures
-peripheral or limiting structures-peripheral or limiting structures

Supporting structuresSupporting structures
 Def-Def-
““Those areas of maxillary andThose areas of maxillary and
mandibular edentulous ridges that aremandibular edentulous ridges that are
considered best suited to carry theconsidered best suited to carry the
forces of mastication when denturesforces of mastication when dentures
are in function.” (GPT-8)are in function.” (GPT-8)

 Maxillary and mandibular denturesMaxillary and mandibular dentures
transfer occlusal loads to these so calledtransfer occlusal loads to these so called
supporting structures .supporting structures .
 The ultimate support for a denture isThe ultimate support for a denture is
provided by the underlying bone which isprovided by the underlying bone which is
covered by mucous membrane. Support iscovered by mucous membrane. Support is
provided by maxillae and palatine boneprovided by maxillae and palatine bone
in case of maxillary denture. Forin case of maxillary denture. For
mandibular denture support is providedmandibular denture support is provided
by mandible.by mandible.

 In both maxilla and mandible type of boneIn both maxilla and mandible type of bone
and mucous membrane overlying it, differsand mucous membrane overlying it, differs
from area to area.from area to area.
 Each type of tissue found in oral cavityEach type of tissue found in oral cavity
has its own characteristic ability to resisthas its own characteristic ability to resist
external forces depending on its natureexternal forces depending on its nature
and histological makeup i.e type of boneand histological makeup i.e type of bone
and mucous membrane.and mucous membrane.
 Stress bearing and relief areasStress bearing and relief areas

Hard tissues-Hard tissues-
 The requirement of ideal support is theThe requirement of ideal support is the
presence of tissues that are relativelypresence of tissues that are relatively
resistant to remodeling and resorptiveresistant to remodeling and resorptive
changes.changes.
 Minimizing the pressures in thoseMinimizing the pressures in those
regions, which are most susceptible toregions, which are most susceptible to
resorption and directing the forcesresorption and directing the forces
towards those regions, which are relativelytowards those regions, which are relatively
resistant to resorption can help to maintainresistant to resorption can help to maintain
healthy residual ridges.healthy residual ridges.

 2 types of bones are seen2 types of bones are seen
-compact or cortical bone-compact or cortical bone
-cancellous or trabecular bone-cancellous or trabecular bone

Difference in ridge resorption inDifference in ridge resorption in
compact and cancellous bone-compact and cancellous bone-
 It has been suggested that bone resorptionIt has been suggested that bone resorption
at any site is a chemotactic phenomenon,at any site is a chemotactic phenomenon,
that is it is initiated by release of somethat is it is initiated by release of some
soluble factors that attract circulatingsoluble factors that attract circulating
monocytes to the target site. Osteoclasts,monocytes to the target site. Osteoclasts,
the cells responsible for bone resorption arethe cells responsible for bone resorption are
nothing but modified monocytes.nothing but modified monocytes.
 Degree of mineralization is less inDegree of mineralization is less in
cancellous bone, so effects of resorptioncancellous bone, so effects of resorption
are more pronounced in cancellous bone.are more pronounced in cancellous bone.

Oral Mucous MembraneOral Mucous Membrane --
The bone of upper and lower edentulousThe bone of upper and lower edentulous
jaws, and the oral cavity is lined with a softjaws, and the oral cavity is lined with a soft
tissue that is known as ‘mucous membrane’.tissue that is known as ‘mucous membrane’.
Denture bases rest on the mucousDenture bases rest on the mucous
membrane, which serve as a cushion betweenmembrane, which serve as a cushion between
denture base and supporting bone.denture base and supporting bone.
The mucous membrane composed of :-The mucous membrane composed of :-
(i) Mucosa(i) Mucosa
(ii) Sub mucosa(ii) Sub mucosa

1)1) MucosaMucosa: -: -
Mucosa is formed by stratifiedMucosa is formed by stratified
squamous epithelium cells.squamous epithelium cells.
There is subjacent narrow layer ofThere is subjacent narrow layer of
connecting tissue to the mucosa, knownconnecting tissue to the mucosa, known
asas laminalamina propriapropria..

2)2) Sub mucosaSub mucosa:: --
Sub mucosa is formed by connective tissue.Sub mucosa is formed by connective tissue.
Connective tissue varies in character fromConnective tissue varies in character from
dense to loose alveolar tissue and also variesdense to loose alveolar tissue and also varies
considerably in thickness.considerably in thickness.
It may contain glandular, fat or muscle cells.It may contain glandular, fat or muscle cells.
Submucosa transmit the blood and nerveSubmucosa transmit the blood and nerve
supply to the mucosa.supply to the mucosa.
Sub mucosa attaches mucosa to theSub mucosa attaches mucosa to the
periosteal covering of the bone.periosteal covering of the bone.

 Some parts of the masticatorySome parts of the masticatory
mucosa are without a distinct submucousmucosa are without a distinct submucous
layer, yet dense connective tissue of thelayer, yet dense connective tissue of the
lamina propria firmly binds the mucosa tolamina propria firmly binds the mucosa to
underlying periosteum. Although not asunderlying periosteum. Although not as
effective in providing resiliency, thiseffective in providing resiliency, this
connective tissue layer serves as aconnective tissue layer serves as a
protective base for the mucosa.protective base for the mucosa.

Classification of oral mucosa-Classification of oral mucosa-
Depending on its location in mouth, oralDepending on its location in mouth, oral
mucosa classified into three categories –mucosa classified into three categories –
Oral mucous membrane
Masticatory Lining Specialized

Limiting structures-Limiting structures-
 The functional anatomy of mouth determines theThe functional anatomy of mouth determines the
extent of the basal surface of denture.extent of the basal surface of denture.
 The denture base should include the maximumThe denture base should include the maximum
surface possible within the limits of the health andsurface possible within the limits of the health and
function of the tissues it covers and contacts i.e itfunction of the tissues it covers and contacts i.e it
should cover all the available basal seat tissuesshould cover all the available basal seat tissues
without interfering in action of any of the structureswithout interfering in action of any of the structures
that contact or surround it.that contact or surround it.
 The anatomy in consideration is anatomy inThe anatomy in consideration is anatomy in
function rather than descriptive anatomy.function rather than descriptive anatomy.www.indiandentalacademy.comwww.indiandentalacademy.com

 Term ‘Border area’ refers to the mucosal surfaceTerm ‘Border area’ refers to the mucosal surface
area which contacts the denture borders andarea which contacts the denture borders and
surrounds the spaces which are occupied bysurrounds the spaces which are occupied by
denture flanges.denture flanges.
 Border molding procedures are used to recordBorder molding procedures are used to record
limiting structures properly. There are 2 mainlimiting structures properly. There are 2 main
objectives of border molding in recording theobjectives of border molding in recording the
limiting structures-limiting structures-
1. to establish correct flange length and1. to establish correct flange length and
border thicknessborder thickness
2. to achieve retention through border seal.2. to achieve retention through border seal.

LIMITING STRUCTURES INLIMITING STRUCTURES IN
MAXILLARY REGIONMAXILLARY REGION

 Labial frenumLabial frenum
 Labial vestibuleLabial vestibule
 Buccal frenumBuccal frenum
 Buccal vestibuleBuccal vestibule
 Hamular notchHamular notch
 Vibrating linesVibrating lines
 Fovea palatinaeFovea palatinae

1. Labial frenum1. Labial frenum
 Term frenum or frenulum refers to aTerm frenum or frenulum refers to a
connecting fold of mucous membraneconnecting fold of mucous membrane
serving to support or retain a part.serving to support or retain a part.
 labial frenum, is a fold of mucouslabial frenum, is a fold of mucous
membrane extends from the labial mucousmembrane extends from the labial mucous
membrane reflection area to or towardsmembrane reflection area to or towards
the slop or crest of residual ridge at thethe slop or crest of residual ridge at the
median line.median line.

 It divides the labial vestibule intoIt divides the labial vestibule into
approximately equal but asymmetrical leftapproximately equal but asymmetrical left
and right labial vestibule.and right labial vestibule.
 It starts superiorly in a fan shape andIt starts superiorly in a fan shape and
converges as it descends to its terminalconverges as it descends to its terminal
attachment on the labial side of the ridge.attachment on the labial side of the ridge.
 It contains no muscle and has no actionIt contains no muscle and has no action
of its own.of its own.

 The action of the lip inThe action of the lip in
this area is mainlythis area is mainly
vertical so the labialvertical so the labial
notch in maxillarynotch in maxillary
denture must be justdenture must be just
wide and deep enoughwide and deep enough
to allow the frenum toto allow the frenum to
pass through it.pass through it.
 The denture bordersThe denture borders
should not only be cutshould not only be cut
lower but also havelower but also have
less thickness adjacentless thickness adjacent
to labial notch.to labial notch.

House classifiedHouse classified
frenal attachment infrenal attachment in
3 classes-3 classes-
 class1- high inclass1- high in
maxilla or low inmaxilla or low in
mandible withmandible with
respect to crest ofrespect to crest of
ridge.ridge.

 class 2- mediumclass 2- medium

 class 3- freniclass 3- freni
encroach onencroach on
the crest ofthe crest of
the ridge andthe ridge and
may interferemay interfere
with denturewith denture
seal, mightseal, might
requirerequire
surgicalsurgical
correction.correction.

Vertical incisiveVertical incisive
pads-pads-
 When lip is raisedWhen lip is raised
and pulledand pulled
horizontally forward,horizontally forward,
a pad ofa pad of
submucosal softsubmucosal soft
tissue in the shapetissue in the shape
of vertical column isof vertical column is
sometimessometimes
observed on eachobserved on each
side of maxillaryside of maxillary
labial frenum, arelabial frenum, are
known as verticalknown as vertical
incisive pads.incisive pads. www.indiandentalacademy.comwww.indiandentalacademy.com

 These are attachments of the superiorThese are attachments of the superior
incisive muscles, which course up fromincisive muscles, which course up from
their attachments.their attachments.
 The basal surface of labial flange of theThe basal surface of labial flange of the
denture should be relieved to allow fordenture should be relieved to allow for
these attachments.these attachments.

Anterior nasal spine-Anterior nasal spine-
 It is not a limiting structure under normal
circumstances, but in instances of severe
ridge resorption, the anterior labial border
of denture should be relieved to avoid
impingement upon the mucosa overlying
the anterior nasal spine, which frequently
becomes a prominent, knife edged,
limiting structure.

Labial vestibuleLabial vestibule
 The portion of the oralThe portion of the oral
cavity that is boundedcavity that is bounded
on one side by theon one side by the
teeth , gingiva andteeth , gingiva and
alveolar ridge (oralveolar ridge (or
residual ridge) and onresidual ridge) and on
the other by the lipsthe other by the lips
anterior to the buccalanterior to the buccal
frenum.frenum.
GPT-8GPT-8
•The labial vestibule is divided into a left and rightThe labial vestibule is divided into a left and right
labial vestibule by the labial frenum.labial vestibule by the labial frenum.

Three objectives which are apparentThree objectives which are apparent
in the labial vestibular region are-in the labial vestibular region are-
1.1. The thickness of the labial flange of the finalThe thickness of the labial flange of the final
impression must be developed according to theimpression must be developed according to the
amount of bone that has been lost from theamount of bone that has been lost from the
labial side of the ridge.labial side of the ridge.
2.2. The labial flange of the impression must haveThe labial flange of the impression must have
sufficient height to reach the reflecting mucoussufficient height to reach the reflecting mucous
membrane of the vestibular space, but shouldmembrane of the vestibular space, but should
not over extend it.not over extend it.
3.3. There must be no interference of the labialThere must be no interference of the labial
flange with action of the lip in function.flange with action of the lip in function.

 The main muscle of theThe main muscle of the
lip, which forms the outerlip, which forms the outer
surface of the labialsurface of the labial
vestibule, is the orbicularisvestibule, is the orbicularis
oris.oris.
 It’s tone depends onIt’s tone depends on
the support it receives fromthe support it receives from
the labial flange and thethe labial flange and the
position of the teeth.position of the teeth.
 Because the fibers runBecause the fibers run
in a horizontal direction, thein a horizontal direction, the
orbicularis oris has only anorbicularis oris has only an
indirect effect on the extentindirect effect on the extent
of an impression and henceof an impression and hence
on the denture base.on the denture base.

Buccal frenumBuccal frenum
 Buccal frenum is aBuccal frenum is a
fold of mucousfold of mucous
membrane, extendsmembrane, extends
from the buccalfrom the buccal
mucous membranemucous membrane
reflection area to orreflection area to or
towards the slop ortowards the slop or
crest of residualcrest of residual
ridge.ridge.
• The buccal frenum forms the dividing line betweenThe buccal frenum forms the dividing line between
the labial and buccal vestibulesthe labial and buccal vestibules..

 It is sometimesIt is sometimes
a single fold ofa single fold of
mucousmucous
membrane,membrane,
sometimessometimes
double, and indouble, and in
some mouth,some mouth,
broad and fanbroad and fan
shaped.shaped.

Three muscles are attached in this regionThree muscles are attached in this region
1.1. The levator anguli oris (caninus) muscle attachesThe levator anguli oris (caninus) muscle attaches
beneath the frenum and affects it’s position.beneath the frenum and affects it’s position.
2.2. The buccinator pulls it backward.The buccinator pulls it backward.
3.3. Orbicularis oris pulls it forward.Orbicularis oris pulls it forward.
However Sicher states categorically thatHowever Sicher states categorically that
muscles are never found in these folds, whichmuscles are never found in these folds, which
contain a variable amount of loose connectivecontain a variable amount of loose connective
tissue between two layers of mucous membrane.tissue between two layers of mucous membrane.

 Because of muscle attachments, itBecause of muscle attachments, it
requires more clearance for its action( inrequires more clearance for its action( in
both horizontal and vertical direction) thanboth horizontal and vertical direction) than
the labial frenum does.the labial frenum does.
 Inadequate provision for the buccalInadequate provision for the buccal
frenum or excess thickness of the flangefrenum or excess thickness of the flange
distal to the buccal notch can causedistal to the buccal notch can cause
dislodgement of the denture when thedislodgement of the denture when the
cheeks are moved posteriorly as in broadcheeks are moved posteriorly as in broad
smile.smile.

 It records in the
impression as a
buccal notch
which is
properly
relieved and
molded.
• It should be cresentric in form, rather thanIt should be cresentric in form, rather than
‘V’ shaped.‘V’ shaped.

Buccal vestibuleBuccal vestibule
 ItIt is defined asis defined as ““the portion of oral cavitythe portion of oral cavity
that is bounded on one side by the teeth,that is bounded on one side by the teeth,
gingiva and alveolar ridge (residualgingiva and alveolar ridge (residual
alveolar ridge) and on the lateral side byalveolar ridge) and on the lateral side by
the cheek posterior to the buccal frenula”.the cheek posterior to the buccal frenula”.
GPT-8GPT-8

 The buccalThe buccal
vestibule liesvestibule lies
opposite theopposite the
tuberositytuberosity
and extendsand extends
from thefrom the
buccalbuccal
frenum to thefrenum to the
hamularhamular
notch.notch.

The size of the buccal vestibule varies withThe size of the buccal vestibule varies with
 contraction of the buccinator muscle,contraction of the buccinator muscle,
 the position of the mandible, andthe position of the mandible, and
 the amount of bone lost from the maxilla.the amount of bone lost from the maxilla.

 The extent of the buccal vestibule can beThe extent of the buccal vestibule can be
deceiving because the coronoid processdeceiving because the coronoid process
obscures it when the mouth is openedobscures it when the mouth is opened
wide. Therefore it should be examinedwide. Therefore it should be examined
with the mouth as nearly closed aswith the mouth as nearly closed as
possible.possible.
 This space usually is higher than anyThis space usually is higher than any
other part of the border.other part of the border.

 The size and shape of the distal end ofThe size and shape of the distal end of
the buccal flange of the denture mustthe buccal flange of the denture must
be adjusted according to the ramusbe adjusted according to the ramus
and the coronoid process of theand the coronoid process of the
mandible.mandible.

 Coronomaxillary SpaceCoronomaxillary Space --
(J.Prosthet.Dent 1987:57; 186-190.(J.Prosthet.Dent 1987:57; 186-190.
N.S.Arbree, A.A.Yurkstas, and J.H.Kronman.)N.S.Arbree, A.A.Yurkstas, and J.H.Kronman.)
 Definition:- The coronomaxillary space is thatDefinition:- The coronomaxillary space is that
anatomic region that lies medial to the coronoidanatomic region that lies medial to the coronoid
process and lateral to the maxillary tuberosity.process and lateral to the maxillary tuberosity.

 Terms used to identify the coronomaxillaryTerms used to identify the coronomaxillary
space,are :-space,are :-
 1- Buccal space or vestibule,1- Buccal space or vestibule,
2- Buccal pocket,2- Buccal pocket,
3-3- Tuberosity sulcusTuberosity sulcus
4- Distobuccal angle of the vestibule,4- Distobuccal angle of the vestibule,
5- Buccal sulcus,5- Buccal sulcus,
6- Buccal pouch,6- Buccal pouch,
7- Buccal mucous membrane reflection7- Buccal mucous membrane reflection
region,region,
8- Postmalar area,8- Postmalar area,
9-9- Retrozygomatic spaceRetrozygomatic space..

Clinical ImplicationsClinical Implications:-:-

To get the maximum retentive qualities of theTo get the maximum retentive qualities of the
prosthesis, each patient should be evaluated forprosthesis, each patient should be evaluated for
variation in the coronomaxillary space size duringvariation in the coronomaxillary space size during
mandibular opening, as the size of the space ismandibular opening, as the size of the space is
primarily influenced by the action of the coronoidprimarily influenced by the action of the coronoid
process.process.

 In someIn some
patients coronoidpatients coronoid
process appearsprocess appears
to flare laterallyto flare laterally
at its height. Forat its height. For
these patientsthese patients
space oftenspace often
remain same orremain same or
becomes widerbecomes wider
during opening ofduring opening of
the mouth.the mouth.

 The coronoidThe coronoid
Process may beProcess may be
relatively straight orrelatively straight or
constricting medially .constricting medially .
For these patientsFor these patients
opening of theopening of the
mandible can resultmandible can result
in narrowing of thein narrowing of the
space.space.

 If the space narrowsIf the space narrows
during opening, anyduring opening, any
horizontal overextensionhorizontal overextension
into the space wouldinto the space would
result in denture baseresult in denture base
contact and loss ofcontact and loss of
retention.retention.
 In this region borderIn this region border
molding proceduremolding procedure
should include openingshould include opening
and closing, togetherand closing, together
with protrusion, andwith protrusion, and
lateral movements oflateral movements of
the jaw.the jaw.

 If coronomaxillaryIf coronomaxillary
space broadens orspace broadens or
remains of same size onremains of same size on
opening, the functionalopening, the functional
filling of this space withfilling of this space with
the denture flangethe denture flange
becomes important.becomes important.
border molding should notborder molding should not
be done with open wide,be done with open wide,
protrude, or any lateralprotrude, or any lateral
movements.movements.
•Here a gentle molding of the region is done byHere a gentle molding of the region is done by
pulling the cheek out, down and inwards.pulling the cheek out, down and inwards.

Microscopic features of labial andMicroscopic features of labial and
Buccal vestibuleBuccal vestibule --
- The mucous membrane lining of vestibule isThe mucous membrane lining of vestibule is
relatively thin.relatively thin.
- The submucosal layer is thick and containsThe submucosal layer is thick and contains
large amount of loose areolar tissue and elastic fiber.large amount of loose areolar tissue and elastic fiber.
- The mucosa of the vestibular space isThe mucosa of the vestibular space is
classified as lining mucosa.classified as lining mucosa.
- Mucosa is devoid of keratinized layer and isMucosa is devoid of keratinized layer and is
freely movable with the tissue to which it is attachedfreely movable with the tissue to which it is attached
because of the elastic nature of the lamina propria.because of the elastic nature of the lamina propria.

Hamular notchHamular notch

Hamular notch is aHamular notch is a
displaceable area,displaceable area,
about 2mm wideabout 2mm wide
between thebetween the
tuberosity of thetuberosity of the
maxilla and themaxilla and the
hamular process ofhamular process of
the medial pterygoidthe medial pterygoid
plateplate..
Also called as pterygomaxillary notchAlso called as pterygomaxillary notch

Clinical SignificanceClinical Significance --
 This notch is used as a boundary of the posteriorThis notch is used as a boundary of the posterior
border of the maxillary denture, back of theborder of the maxillary denture, back of the
tuberosity.tuberosity.
 The impression should not end on the tuberosity,The impression should not end on the tuberosity,
otherwise it will result in nonretentive dentureotherwise it will result in nonretentive denture
because peripheral seal is not possible inbecause peripheral seal is not possible in
nonresilient area of tuberosity.nonresilient area of tuberosity.
 The tissue in the centre of the deep part of theThe tissue in the centre of the deep part of the
hamular notch, can be safely displaced by thehamular notch, can be safely displaced by the
posterior palatal border of the denture to help inposterior palatal border of the denture to help in
achieving a seal in this region called asachieving a seal in this region called as pterygo-pterygo-
maxillary seal.maxillary seal.

 The tip of the pterygoid hamulus is 2-3 mmThe tip of the pterygoid hamulus is 2-3 mm
posteromedial to the distal limit of maxillaryposteromedial to the distal limit of maxillary
residual ridge. However it may be located on theresidual ridge. However it may be located on the
line with crest of ridge or sometimes even lateralline with crest of ridge or sometimes even lateral
to this line.to this line.
 This variation is significant in that it affects theThis variation is significant in that it affects the
length and the direction of pterygomaxillary seallength and the direction of pterygomaxillary seal
so it becomes very important to determine theso it becomes very important to determine the
location of hamulus by palpation.location of hamulus by palpation.

 PterygomaxillaryPterygomaxillary
seal occupiesseal occupies
the entire widththe entire width
of hamularof hamular
notch. The sealnotch. The seal
begins atbegins at
pterygomaxillarypterygomaxillary
notch andnotch and
usually extendsusually extends
5-7 mm5-7 mm
anteromedially.anteromedially.

 Also overextensions at the hamularAlso overextensions at the hamular
notches will not be tolerated because ofnotches will not be tolerated because of
pressure on the pterygoid hamulus andpressure on the pterygoid hamulus and
interference with the pterygomandibularinterference with the pterygomandibular
raphe.raphe.
 Special care should be taken in theSpecial care should be taken in the
grossly resorbed alveolar ridge, wheregrossly resorbed alveolar ridge, where
hamular notch disappears and raphehamular notch disappears and raphe
becomes more prominent.becomes more prominent.

 When the mouth isWhen the mouth is
opened wide, theopened wide, the
pterygomandibularpterygomandibular
raphe is pulledraphe is pulled
forward. If the dentureforward. If the denture
extends too far intoextends too far into
the hamular notch,the hamular notch,
the mucousthe mucous
membrane coveringmembrane covering
the raphe will bethe raphe will be
traumatizedtraumatized

Review of LiteratureReview of Literature --
Aust.Dent.J.1981:26;218-21.Aust.Dent.J.1981:26;218-21.
B.C.W.BarkerB.C.W.Barker, After dissection of, After dissection of
cadaver heads and observation ,he gavecadaver heads and observation ,he gave
a note i.e. Little or no movements occursa note i.e. Little or no movements occurs
in the mucosa here. Dissection ofin the mucosa here. Dissection of
submucosal structure related to the notchsubmucosal structure related to the notch
showed variation in arrangements andshowed variation in arrangements and
form which did not conform entirely withform which did not conform entirely with
textbook descriptions.textbook descriptions.

PterygomandibularPterygomandibular
RapheRaphe --
 PterygomandibularPterygomandibular
raphe or ligament originatesraphe or ligament originates
from the pterygoid hamulusfrom the pterygoid hamulus
of the medial pterygoidof the medial pterygoid
lamina and attaches to thelamina and attaches to the
distal end of the mylohyoiddistal end of the mylohyoid
ridge.ridge.
 It is partly, origin ofIt is partly, origin of
buccinator muscle laterallybuccinator muscle laterally
and superior constrictorand superior constrictor
muscle medially.muscle medially.

Palatine fovea region-Palatine fovea region-
 The fovea palatinae are indentationsThe fovea palatinae are indentations
near the midline of the palate in posteriornear the midline of the palate in posterior
region formed by coalescence of severalregion formed by coalescence of several
mucous membrane ducts.mucous membrane ducts.
 They are very prominent in someThey are very prominent in some
individuals, whereas in others they areindividuals, whereas in others they are
barely visible or may be absent.barely visible or may be absent.

Usually theUsually the
posteriorposterior
vibrating line isvibrating line is
found ,2 mmfound ,2 mm
anterior to theanterior to the
foveae palatine,foveae palatine,
but they can bebut they can be
found on orfound on or
anterior to theanterior to the
vibrating line.vibrating line.

Review of LiteratureReview of Literature
((1) J Prosthet Dent: 1975; 33,504-510.1) J Prosthet Dent: 1975; 33,504-510.
T.L.LyeT.L.Lye conducted clinical, radiographicconducted clinical, radiographic
and histological studies of fovea palatine andand histological studies of fovea palatine and
concluded that, fovea palatine were positionedconcluded that, fovea palatine were positioned
1 .31 mm in front of the vibrating line in 70% of1 .31 mm in front of the vibrating line in 70% of
the cases.the cases.
Histologically, complex nerve endingsHistologically, complex nerve endings
were found just anterior to the fovea andwere found just anterior to the fovea and
spreading to the soft palate.spreading to the soft palate.

Dental.J.1983:28; 166-70.Dental.J.1983:28; 166-70.
 A clinical study was conducted byA clinical study was conducted by S.B.KengS.B.Keng andand ROWROW
A.MA.M.,on edentulous patients to determine the distance of the.,on edentulous patients to determine the distance of the
vibrating line to the fovea palatine. The results indicated thatvibrating line to the fovea palatine. The results indicated that
the vibrating line is located 2.62 mm. (mean of 160 subjects)the vibrating line is located 2.62 mm. (mean of 160 subjects)
anterior to the fovea palatine.anterior to the fovea palatine.
 There was a significant correlation between the distances ofThere was a significant correlation between the distances of
vibrating line to the fovea for different type of soft palatevibrating line to the fovea for different type of soft palate
contour. Soft palate with deep slope (class III) has thecontour. Soft palate with deep slope (class III) has the
vibrating line at or just in front of the fovea, while class IIvibrating line at or just in front of the fovea, while class II
medium contour was 2.3 m.m. anterior to fovea, and class Imedium contour was 2.3 m.m. anterior to fovea, and class I
flat contour of the soft palate line located approximately 4flat contour of the soft palate line located approximately 4
m.m. anterior to the fovea palatine.m.m. anterior to the fovea palatine.

Fovea palatini and posterior borderFovea palatini and posterior border
of dentureof denture
 According to Boucher as fovea palatini are close toAccording to Boucher as fovea palatini are close to
vibrating line and always in soft tissues, whichvibrating line and always in soft tissues, which
makes them an ideal guide for location of posteriormakes them an ideal guide for location of posterior
border of denture.border of denture.
 According to Winkler fovea palatini should be usedAccording to Winkler fovea palatini should be used
only as guidelines to the placement of posterioronly as guidelines to the placement of posterior
palatal seal. The dentist who observes the foveapalatal seal. The dentist who observes the fovea
and utilizes these anatomic landmarks as posteriorand utilizes these anatomic landmarks as posterior
extent of denture base can deprive his patients ofextent of denture base can deprive his patients of
several millimeters up to a centimeter or more ofseveral millimeters up to a centimeter or more of
tissue coverage depending on the palataltissue coverage depending on the palatal
configuration.configuration.


AnteriorAnterior
vibrating line-vibrating line-
 Anterior vibrating lineAnterior vibrating line
is an imaginary lineis an imaginary line
located at the junctionlocated at the junction
of the attachedof the attached
tissues overlying thetissues overlying the
hard palate and thehard palate and the
movable tissues ofmovable tissues of
the immediatelythe immediately
adjacent soft palate.adjacent soft palate.
Vibrating lines of palate-Vibrating lines of palate-

 This can be located either by valsulvaThis can be located either by valsulva
maneuver or by instructing patient to saymaneuver or by instructing patient to say
“ah” with short vigorous bursts.“ah” with short vigorous bursts.
 Due to projection of posterior nasal spineDue to projection of posterior nasal spine
anterior vibrating line is not a straight lineanterior vibrating line is not a straight line
between hamular processes.between hamular processes.
 At the midline it usually passes about 2 mmAt the midline it usually passes about 2 mm
in front of the fovea palatinae.in front of the fovea palatinae.

 Posterior vibrating line is an imaginary line at thePosterior vibrating line is an imaginary line at the
junction of the aponeurosis of tensor veli palatinijunction of the aponeurosis of tensor veli palatini
muscle and the muscular portion of the softmuscle and the muscular portion of the soft
palate.palate.
 It represents the demarcation between that partIt represents the demarcation between that part
of the soft palate that has limited or shallowof the soft palate that has limited or shallow
movement during function and the remainder ofmovement during function and the remainder of
soft palate that is markedly displaced duringsoft palate that is markedly displaced during
function.function.
 Posterior vibrating line is visualized byPosterior vibrating line is visualized by
instructing the patient to say “ah” in a normalinstructing the patient to say “ah” in a normal
unexaggerated fashion.unexaggerated fashion.

• The distal end of the upper denture must extend at
least to vibrating lines. In most instances the denture
should end 1-2 mm posterior to vibrating lines.
 Direction of the vibrating line usually varies accordingDirection of the vibrating line usually varies according
to the shape of palate ; the higher the vault , the moreto the shape of palate ; the higher the vault , the more
abrupt and forward the vibrating line. In a mouth withabrupt and forward the vibrating line. In a mouth with
flat vault , the vibrating line is usually farther posteriorflat vault , the vibrating line is usually farther posterior
and has a good curvature, affording a broader PPSA.and has a good curvature, affording a broader PPSA.
 TheThe M.M.HouseM.M.House classification is customarily used toclassification is customarily used to
designate the shape of the soft palate and itdesignate the shape of the soft palate and it
describes the amount of posterior tissue that willdescribes the amount of posterior tissue that will
accept the posterior palatal seal –accept the posterior palatal seal –

Class IClass I – More than 5mm of– More than 5mm of
movable tissue available formovable tissue available for
post damming .post damming .
 ideal for retention.ideal for retention.
Class IIClass II – 1-5 mm of movable– 1-5 mm of movable
tissue available for posttissue available for post
damming.damming.
 retention is usually possible.retention is usually possible.
Class IIIClass III – Less than 1 mm– Less than 1 mm
movable tissue available formovable tissue available for
post damming.post damming.
 Retention is usually poor.Retention is usually poor.

1. Irving R. Hardy and Krishan K. Kapur.
Posterior border seal –Its rationale and
importance J Prosthet Dent.1958;8;386-397
• Due to the relative instability of the denture
base materials generally used, we have to take
added precaution of scoring the cast at the deepest
point of the posterior palatal seal to counteract the
warpage of the denture.
• If this bead causes any irritation when the
denture is worn, it can be buffed off very easily, and
it may make the difference between excellent and
merely passable retention.

2.2. J prosthet.Dent.1971;25,470-488.J prosthet.Dent.1971;25,470-488.
Sidney I. Silverman-Sidney I. Silverman-
 He did a study on 500 patients whoHe did a study on 500 patients who
required complete denture. The clinicalrequired complete denture. The clinical
findings were evaluated during speechfindings were evaluated during speech
swallowing and respiratory posture.swallowing and respiratory posture.
 Silverman concluded that completeSilverman concluded that complete
maxillary denture can be extended for anmaxillary denture can be extended for an
average of 8.2 mm. dorsally to the vibrating line.average of 8.2 mm. dorsally to the vibrating line.
 The extension varies from 4 to 12 mm.The extension varies from 4 to 12 mm.

3.3. J.Prosthet.Dent1973:23:484-93.J.Prosthet.Dent1973:23:484-93.
William E. AvantWilliam E. Avant did this study to do comparisondid this study to do comparison
of different type of palatal seal in relation ofof different type of palatal seal in relation of
complete denture retention.complete denture retention.
 Conclusions of this study were –Conclusions of this study were –
1.1. A posterior palatal seal is necessary forA posterior palatal seal is necessary for
optimum retention of maxillary completeoptimum retention of maxillary complete
dentures.dentures.
2.2. Each type of posterior palatal seal tested inEach type of posterior palatal seal tested in
this study increased retention effectively.this study increased retention effectively.
3.3. No one type of posterior palatal seal thatNo one type of posterior palatal seal that
was tested ,proved to be superior than other.was tested ,proved to be superior than other.

44) J.Prothet .dent.1975:34; 605-13.) J.Prothet .dent.1975:34; 605-13.
H.NikoukariH.Nikoukari did a study at school of dentistry, Mashad,did a study at school of dentistry, Mashad,
Iran.Iran.
This study was designed to measure the dimension andThis study was designed to measure the dimension and
displacement pattern of the posterior palatal seal in differentdisplacement pattern of the posterior palatal seal in different
palatal shapes .The effect of different materials on thepalatal shapes .The effect of different materials on the
displacement of tissue in the posterior palatal area were alsodisplacement of tissue in the posterior palatal area were also
evaluated .evaluated .
 It was concluded that the best posterior palatal seal can beIt was concluded that the best posterior palatal seal can be
achieved by using green modeling compound or korecta waxachieved by using green modeling compound or korecta wax
no 4 .no 4 .
 For establishing the posterior palatal seal area ,the posteriorFor establishing the posterior palatal seal area ,the posterior
border should only be scraped on the cast for betterborder should only be scraped on the cast for better
adaptation.adaptation.
 No apparent changes of tissue displacement were found inNo apparent changes of tissue displacement were found in
different palatal shapes. However width of the posterior palataldifferent palatal shapes. However width of the posterior palatal
seal area in flat palate was greater than deep and mediumseal area in flat palate was greater than deep and medium
palate.palate.

5.5.Journal of prosthetic dentistry 2003;12 :265-270Journal of prosthetic dentistry 2003;12 :265-270
Behnoush RashediBehnoush Rashedi andand Vicki KVicki K PetropoulosPetropoulos, conducted a, conducted a
survey of U.S. dental schools in 2001 ,to determine thesurvey of U.S. dental schools in 2001 ,to determine the
concepts, techniques used for establishing the post palatalconcepts, techniques used for establishing the post palatal
seal Results from this survey show thatseal Results from this survey show that
 Combinations of clinical methods were most frequentlyCombinations of clinical methods were most frequently
taught for locating the vibrating line.taught for locating the vibrating line.
 The phonation of the “ah” sound was the most popularThe phonation of the “ah” sound was the most popular
single method taught for locating the vibrating line.single method taught for locating the vibrating line.
 Most dental schools (87.5%) teach students to carveMost dental schools (87.5%) teach students to carve
the posterior palatal seal on maxillary master cast.the posterior palatal seal on maxillary master cast.
 Most dental school (93.9%) take the compressibility ofMost dental school (93.9%) take the compressibility of
the palatal tissue into consideration when carving the depth ofthe palatal tissue into consideration when carving the depth of
posterior palatal seal in maxillary master cast.posterior palatal seal in maxillary master cast.

ANATOMIC LANDMARKSANATOMIC LANDMARKS
OF ORAL CAVITY ANDOF ORAL CAVITY AND
THEIR SIGNIFICANCE INTHEIR SIGNIFICANCE IN
COMPLETE DENTURECOMPLETE DENTURE
PATIENTSPATIENTS
DR. PRASOONDR. PRASOON
SHUKLASHUKLA

 IntroductionIntroduction
 DefinitionDefinition
 Supporting structuresSupporting structures
1. Bone1. Bone
2.Mucous membrane2.Mucous membrane
 Peripheral or limiting structuresPeripheral or limiting structures

 ConclusionConclusion
 ReferencesReferences

Anatomy of supportingAnatomy of supporting
structuresstructures in maxillaryin maxillary
region-region-

 The foundation for dentures is madeThe foundation for dentures is made
up of bone of the hard palate and residualup of bone of the hard palate and residual
ridge, covered by mucous membrane. Theridge, covered by mucous membrane. The
denture base rests on the mucousdenture base rests on the mucous
membrane, which serves as a cushionmembrane, which serves as a cushion
between the base and the supportingbetween the base and the supporting
bone.bone.

Residual alveolar ridge-Residual alveolar ridge-
DefinitionDefinition (According to GPT-8) –(According to GPT-8) –
““The portion of the alveolar ridge and itsThe portion of the alveolar ridge and its
soft tissue covering ,which remainssoft tissue covering ,which remains
following the removal of teeth.”following the removal of teeth.”
 The socket that surrounds the rootThe socket that surrounds the root
of each natural tooth is called alveolusof each natural tooth is called alveolus
and the bony ridge that supports the teethand the bony ridge that supports the teeth
is the alveolar ridge.is the alveolar ridge.

 When the naturalWhen the natural
teeth are removed, theteeth are removed, the
alveoli begin to fill upalveoli begin to fill up
with the new bone. Atwith the new bone. At
the same time bonethe same time bone
around the margins ofaround the margins of
tooth sockets begin totooth sockets begin to
shrink away.shrink away.
 This shrinkage orThis shrinkage or
resorption is rapid atresorption is rapid at
first six weeks of toothfirst six weeks of tooth
removal, and itremoval, and it
continues at acontinues at a
reduced rate throughout the life and is responsiblereduced rate throughout the life and is responsible
for the formation of RAR.for the formation of RAR.

The alveolar ridges vary greatly in size,The alveolar ridges vary greatly in size,
shape and their ultimate form. This isshape and their ultimate form. This is
dependent on the following factorsdependent on the following factors --
 Variation in bone size and its degreeVariation in bone size and its degree
of calcification in individuals.of calcification in individuals.
 Teeth show wide individual variationTeeth show wide individual variation
in size. Large teeth are supported by bulkyin size. Large teeth are supported by bulky
ridges and smaller teeth by narrow ones.ridges and smaller teeth by narrow ones.
 The amount of bone lost prior to theThe amount of bone lost prior to the
extraction of teeth.extraction of teeth.
 The amount of alveolar process removedThe amount of alveolar process removed
during extraction of teeth.during extraction of teeth.

 Rate and degree of resorption: - During theRate and degree of resorption: - During the
first six weeks after the extraction of teeth, thefirst six weeks after the extraction of teeth, the
rate of resorption is rapid, thereafter it continuesrate of resorption is rapid, thereafter it continues
throughout the life at an ever decreasing pace.throughout the life at an ever decreasing pace.
 The effect of previous denture: - ill fittingThe effect of previous denture: - ill fitting
denture, or dentures with occluding naturaldenture, or dentures with occluding natural
teeth, may cause rapid resorption of the alveolarteeth, may cause rapid resorption of the alveolar
process in the areas where they causeprocess in the areas where they cause
excessive pressure or lateral stresses.excessive pressure or lateral stresses.
 The relative length of the time for whichThe relative length of the time for which
different parts of the jaw has been edentulous.different parts of the jaw has been edentulous.
 Person’s general health.Person’s general health.

 According to size RAR can be-According to size RAR can be-
-large-large
-medium-medium
-small-small

large medium
small

 According to shape RAR can be-According to shape RAR can be-
- smooth- smooth
- irregular- irregular
- knife edge- knife edge
- flat- flat

IrregularSmooth
Knife-edgeFlat

Types of Alveolar ridges, palateTypes of Alveolar ridges, palate
formation and their significanceformation and their significance
Alveolar Ridge
shape
‘square to gently
rounded
Flat Palate
With
small ridge
’tapering or
V’ Shaped

square to gently
rounded
This is mostThis is most
favorable kind offavorable kind of
ridge because –ridge because –
 The centre ofThe centre of
the palate presentsthe palate presents
an almost flatan almost flat
horizontal area andhorizontal area and
this will aid inthis will aid in
retention.retention.
 The roomyThe roomy
sulcus allows for thesulcus allows for the
development of gooddevelopment of good
peripheral seal.peripheral seal.
Flat surface
 The well developed ridges resist lateral and anteroposteriorThe well developed ridges resist lateral and anteroposterior
movement of the denture.movement of the denture.

tapering or V’
Shaped
• It is usuallyIt is usually
associated with thickassociated with thick
bulky ridges. This isbulky ridges. This is
an unfavorablean unfavorable
formation.formation.
The forces ofThe forces of
adhesion andadhesion and
cohesion are not atcohesion are not at
right angles toright angles to
surface whensurface when
counteracting thecounteracting the
normal displacingnormal displacing
forces of gravity.forces of gravity.
V’ shaped

(iii) Flat palate with small(iii) Flat palate with small
ridgesridges
This is anThis is an
unfavorable formationunfavorable formation
because –because –
– The illThe ill
developed ridges dodeveloped ridges do
not resist lateral andnot resist lateral and
anterior-posterioranterior-posterior
movement of themovement of the
denture.denture.
– Shallow SulcusShallow Sulcus
do not form a gooddo not form a good
Peripheral seal.Peripheral seal.
Shallow Flat Palate

 UnsupportedUnsupported
alveolar soft tissuesalveolar soft tissues
are frequently foundare frequently found
in the edentulousin the edentulous
anterior maxillaanterior maxilla
which has beenwhich has been
opposed by anopposed by an
island of naturalisland of natural
anterior teeth with ananterior teeth with an
edentulous posterioredentulous posterior
mandible.mandible.
 During masticationDuring mastication
the upper denturethe upper denture
‘see-saws’ leading to‘see-saws’ leading to
disproportionatedisproportionate
resorption.resorption.

 Soft tissues areSoft tissues are
compressiblecompressible
and the dentureand the denture
developsdevelops
increasingincreasing
instability.instability.
 Excessive softExcessive soft
tissue needstissue needs
surgicalsurgical
removal.removal.

Microscopic features of residual ridgesMicroscopic features of residual ridges
 The mucous membrane isThe mucous membrane is
attached to theattached to the
periosteum of the bone byperiosteum of the bone by
the connective tissue ofthe connective tissue of
the sub mucosa.the sub mucosa.
 The stratified squamousThe stratified squamous
epithelium is thicklyepithelium is thickly
keratinized.keratinized.
 The sub mucosa isThe sub mucosa is
devoid of fat or glandulardevoid of fat or glandular
cells and it iscells and it is
characterized by densecharacterized by dense
collegenous fibers that are contiguous with laminacollegenous fibers that are contiguous with lamina
propriapropria.. www.indiandentalacademy.comwww.indiandentalacademy.com

 The outer surface of
bone in the region of
crest of RAR (most
coronal portion of
ridge) is usually
compact in nature.
This compact bone in
combination with
tightly attached
keratinized mucous
membrane makes
crest of RAR
histologically best
able to provide primary
support for the
denture.

RAR- a primary stress bearingRAR- a primary stress bearing
areaarea ??????
 According to Prosthodontic Treatment forAccording to Prosthodontic Treatment for
Edentulous Patients by Zarb and Bolender-Edentulous Patients by Zarb and Bolender-
““the bone in this region is subject tothe bone in this region is subject to
resorption, which limits it’s potential forresorption, which limits it’s potential for
support, unlike the palate, which is resistantsupport, unlike the palate, which is resistant
to resorption. Because of this, ridge crestto resorption. Because of this, ridge crest
should be looked on as a secondaryshould be looked on as a secondary
supporting area.”supporting area.”

 TheyThey
ConsiderConsider
““horizontalhorizontal
portion ofportion of
hard palatehard palate
lateral tolateral to
midline” asmidline” as
primaryprimary
supportingsupporting
area forarea for
denture.denture.

 In a patientIn a patient
where tooth werewhere tooth were
extracted longextracted long
time backtime back
(years), ridge(years), ridge
becomesbecomes
smaller and crestsmaller and crest
of ridge in manyof ridge in many
cases iscases is
completelycompletely
devoid of smoothdevoid of smooth
cortical bonycortical bony
surface.surface.

Horizontal part of palate lateral to midline shouldHorizontal part of palate lateral to midline should
definitely be considered a primary stress bearing areadefinitely be considered a primary stress bearing area
in these patients.in these patients. www.indiandentalacademy.comwww.indiandentalacademy.com

Palatal region-Palatal region-
Rugae area-Rugae area-
 Rugae are the raised area of dense connectiveRugae are the raised area of dense connective
tissue radiating from the median suture in thetissue radiating from the median suture in the
anterior one third of the palate.anterior one third of the palate.
 Consists of series of ridges in the anterior part ofConsists of series of ridges in the anterior part of
the hard palatethe hard palate
 Mucosa is keratinized and the submucosa isMucosa is keratinized and the submucosa is
fibrousfibrous
 In the area of the rugae, the palate is set at anIn the area of the rugae, the palate is set at an
angle to the residual ridge and is rather thinlyangle to the residual ridge and is rather thinly
covered by soft tissue.covered by soft tissue.

 This area contributes to the stress-bearingThis area contributes to the stress-bearing
role as well as to retention although in arole as well as to retention although in a
secondary capacity.secondary capacity.
 It resists forward movement of denture.It resists forward movement of denture.
 It should be recorded without pressure, if itIt should be recorded without pressure, if it
distorts while making impression it can rebounddistorts while making impression it can rebound
and unseat the denture.and unseat the denture.
 These folds of the mucosa play an importantThese folds of the mucosa play an important
role in speech so dentures should reproduce thisrole in speech so dentures should reproduce this
contour making it very comfortable for thecontour making it very comfortable for the
patient.patient.

Mid palatine raphe-Mid palatine raphe-
 This presents as slightlyThis presents as slightly
elevated bony ridge alongelevated bony ridge along
the midline of hard palate.the midline of hard palate.
 Adequate relief should beAdequate relief should be
provided in this area as-provided in this area as-
- mucosa covering the- mucosa covering the
raphe is extremely thin andraphe is extremely thin and
is traumatized easily.is traumatized easily.
-mucosa is less resilient-mucosa is less resilient
than that covering the ridgesthan that covering the ridges
so it can act as fulcrumso it can act as fulcrum
along which denture rocksalong which denture rocks
when vertical forces arewhen vertical forces are
applied.applied. www.indiandentalacademy.comwww.indiandentalacademy.com

 This areaThis area
provides primaryprovides primary
support tosupport to
denture as itdenture as it
offers maximumoffers maximum
resistance toresistance to
resorption.resorption.
Horizontal portion of hard palate lateral toHorizontal portion of hard palate lateral to
midline-midline-

Lateral surface of hard palateLateral surface of hard palate
It isIt is divided individed in
 anterolateral part containinganterolateral part containing
adipose tissue in submucosaadipose tissue in submucosa
 posterolateral part containingposterolateral part containing
glandular tissue.glandular tissue.
Both of these areas are displaceable theyBoth of these areas are displaceable they
do not provide significant support to thedo not provide significant support to the
denture but this region should be covereddenture but this region should be covered
to provide retention.to provide retention.

Anteriolateral View Posteriolateral View

 These areas should be recorded inThese areas should be recorded in
resting conditionresting condition because when they arebecause when they are
displaced in the final impression, they tenddisplaced in the final impression, they tend
to return to natural form within theto return to natural form within the
completed denture base, and creating ancompleted denture base, and creating an
unseating force on the denture or causingunseating force on the denture or causing
soreness in the patients mouth. Forsoreness in the patients mouth. For
recording these tissue in undistorted form,recording these tissue in undistorted form,
proper relief should be given in the finalproper relief should be given in the final
impression tray.impression tray.

Incisive papilla-Incisive papilla-
 This coversThis covers
the incisivethe incisive
foramen andforamen and
is located inis located in
the midlinethe midline
immediatelyimmediately
behind andbehind and
betweenbetween
centralcentral
incisors.incisors.

ProsthodonticProsthodontic
significances:significances:
 It lies nearer toIt lies nearer to
the crest of thethe crest of the
ridge as resorptionridge as resorption
progresses. Thusprogresses. Thus
the location of thethe location of the
incisive papillaincisive papilla
gives an indicationgives an indication
as to the amount ofas to the amount of
resorption that hasresorption that has
taken place.taken place.


 Incisive papillaIncisive papilla
acts as a guide foracts as a guide for
antero-posteriorantero-posterior
positioning of thepositioning of the
teeth, theteeth, the
labial surfaces oflabial surfaces of
the centralthe central
incisors areincisors are
usually 8-10 mmusually 8-10 mm
in front of thein front of the
papilla.papilla.

 IncisiveIncisive
papilla is usedpapilla is used
to locate theto locate the
midline of themidline of the
dental arch.dental arch.

The nasopalatine nerves and blood vessels passThe nasopalatine nerves and blood vessels pass
through the foramen, and care should be taken thatthrough the foramen, and care should be taken that
the denture base does not impinge on them.the denture base does not impinge on them.www.indiandentalacademy.comwww.indiandentalacademy.com

1. 1. Harold R. Ortman, and Ding H. TsaoHarold R. Ortman, and Ding H. Tsao
:Relationship of the incisive papilla to:Relationship of the incisive papilla to
the maxillary central incisors. Jthe maxillary central incisors. J
Prosthet Dent 1979;42; 492-496Prosthet Dent 1979;42; 492-496
 A study on 38 maxillary casts found that theA study on 38 maxillary casts found that the
average distance between the most anterioraverage distance between the most anterior
point of maxillary central incisors and mostpoint of maxillary central incisors and most
posterior point of the incisive papilla was 12.454posterior point of the incisive papilla was 12.454
mm .mm .

2.J.prosthet.Dent 1981:45;592-97.2.J.prosthet.Dent 1981:45;592-97.
F.MovroskoufisF.Movroskoufis andand
G.M.RetechieG.M.Retechie did a study atdid a study at
dental school London ,UK.dental school London ,UK.
An investigation of 64 angleAn investigation of 64 angle
skeletal class I dental studentsskeletal class I dental students
showed that the incisive papillashowed that the incisive papilla
provides a stable anatomicprovides a stable anatomic
landmark for arranging the labiallandmark for arranging the labial
surface of the central incisorssurface of the central incisors
labial surface is 10.2mmlabial surface is 10.2mm
anterior to the posterior border ofanterior to the posterior border of
the papilla.the papilla.

3) Journal Indian Dent.Asso.1984:56;425-28.3) Journal Indian Dent.Asso.1984:56;425-28.
Kharat D.U. and Madan R.S. carried out a study onKharat D.U. and Madan R.S. carried out a study on
200 subjects (108 men,98 women) of different age group200 subjects (108 men,98 women) of different age group
ranging 20-65 years ,to determine the distances fromranging 20-65 years ,to determine the distances from
incisal edge of the maxillary central incisor to theincisal edge of the maxillary central incisor to the
papilla.papilla.
 The findings of the study showed that the meanThe findings of the study showed that the mean
distance of maxillary incisal edge to the incisive papilladistance of maxillary incisal edge to the incisive papilla
was 8.16was 8.16 ++ 1.26 mm for men and 7.411.26 mm for men and 7.41 ++ 0.98 mm for0.98 mm for
women.women.
 Conclusion of their study was, the distance fromConclusion of their study was, the distance from
maxillary incisal edge to the incisal papilla in dentulousmaxillary incisal edge to the incisal papilla in dentulous
men is more than the women and this distance remainsmen is more than the women and this distance remains
constant throughout the life.constant throughout the life.

((4) J.Prosthet.Dent.4) J.Prosthet.Dent.
1987:57;712-141987:57;712-14
A.M.H.graveA.M.H.grave andand
P.J.BeckerP.J.Becker compared thecompared the
position of incisive papilla,position of incisive papilla,
in between the two groupsin between the two groups
in their study. The firstin their study. The first
group consisted of existinggroup consisted of existing
complete upper dentures ofcomplete upper dentures of
67 patients(34 men,3367 patients(34 men,33
women). And anotherwomen). And another
group consisted of castgroup consisted of cast
obtained from the 60 youngobtained from the 60 young
adults.adults.

 The results of the study suggests that theThe results of the study suggests that the
labial surface of the maxillary incisorslabial surface of the maxillary incisors
should be 12-13 mm from the posteriorshould be 12-13 mm from the posterior
border of the incisive papilla. Theseborder of the incisive papilla. These
measurements was significantly smaller inmeasurements was significantly smaller in
the sample of dentures examined , whichthe sample of dentures examined , which
suggests a tendency for anterior teeth to besuggests a tendency for anterior teeth to be
placed too far posteriorly in artificial denture.placed too far posteriorly in artificial denture.

(5) J.prosthet.Dent.
1989:61;51-53. H.F.
Grove and L.Cristensen
did a study on 58 subjects
to determine the
orthographic distances
from the posterior of the
incisive papilla to the line
intersecting the distal
contact point of the
maxillary canine.
In 92% of subjects the posterior point of incisive papilla
was approximately 3mm anterior to the line between
the distal points of the canines. Neither gender, age,
nor maxillary arch form affected this distance.www.indiandentalacademy.comwww.indiandentalacademy.com

6.G.C.K. Lau and R.F.K.Clark: the6.G.C.K. Lau and R.F.K.Clark: the
relationship of the incisive papilla to therelationship of the incisive papilla to the
maxillary central incisors and caninemaxillary central incisors and canine
teeth in southern Chinese. Prosthetteeth in southern Chinese. Prosthet
Dent 1993; 70; 86-93Dent 1993; 70; 86-93
                distance of central incisor to the midpoint ofdistance of central incisor to the midpoint of
the incisive papilla - 9.17mmthe incisive papilla - 9.17mm
              distance of central incisor to the posteriordistance of central incisor to the posterior
point of the incisive papilla -12.71mmpoint of the incisive papilla -12.71mm


 Relationship of canine to the incisive papilla.Relationship of canine to the incisive papilla.
The intercanine lines in 57.3% passedThe intercanine lines in 57.3% passed
through the middle third , in 12.25% passedthrough the middle third , in 12.25% passed
through the anterior third and in 32.7% of all thethrough the anterior third and in 32.7% of all the
subjects passed through the posterior third ofsubjects passed through the posterior third of
incisive papilla.incisive papilla.
 All the similar above measurements wereAll the similar above measurements were
also made in Angle’s class1, class 2 and class 3also made in Angle’s class1, class 2 and class 3
jaws. The differences among these were foundjaws. The differences among these were found
statistically insignificant.statistically insignificant.
 Results showed that there is little differenceResults showed that there is little difference
between various ethnic groups.between various ethnic groups.

 Also calledAlso called
malar process ismalar process is
located oppositelocated opposite
the first molarthe first molar
region and isregion and is
commonly seencommonly seen
in mouth that hasin mouth that has
been edentulousbeen edentulous
for long.for long.
Zygomatic process-Zygomatic process-

 SomeSome
denturesdentures
require reliefrequire relief
over the areaover the area
to aid into aid in
retention andretention and
to preventto prevent
soreness ofsoreness of
underlyingunderlying
structures.structures.

Maxillary tuberosity-Maxillary tuberosity-
 MaxillaryMaxillary
representsrepresents
most distalmost distal
portion ofportion of
maxillarymaxillary
alveolaralveolar
ridge.ridge.

 The tuberosityThe tuberosity
region oftenregion often
hangs abnormallyhangs abnormally
low whenlow when
maxillary posteriormaxillary posterior
teeth are retainedteeth are retained
after mandibularafter mandibular
molars are lostmolars are lost
and not replaced,and not replaced,
the max. teeththe max. teeth
extrude bringingextrude bringing
the tuberosity withthe tuberosity with
them.them.
 Often the low hanging tuberosity prevents properOften the low hanging tuberosity prevents proper
location of occlusal plane.location of occlusal plane.www.indiandentalacademy.comwww.indiandentalacademy.com

 Most oftenMost often
enlargements areenlargements are
only fibrous inonly fibrous in
nature.nature.
 In either caseIn either case
invasion ofinvasion of
interalveolarinteralveolar
space in thespace in the
tuberosity areatuberosity area
may prevent themay prevent the
posteriorposterior
extension ofextension of
denture .denture .

Review of literature-Review of literature-
1.JADA vol. 103, Dec 1981,1.JADA vol. 103, Dec 1981,
894. Ryle A. Bell, and894. Ryle A. Bell, and
Richardson.Richardson.
2.Quintessence international2.Quintessence international
1987 :18;465. Sherif E,1987 :18;465. Sherif E,
John unger and Carl StoneJohn unger and Carl Stone
 They have presentedThey have presented
techniques of non surgicaltechniques of non surgical
managemant ofmanagemant of
overhanging tuberosities foroverhanging tuberosities for
CD patients.CD patients.
 Overhanging tuberosities in these cases reduced
intermaxillary space to less than 3 mm. This space did
not allow for the adeqate thickness of U and L acrylic
denture bases. www.indiandentalacademy.comwww.indiandentalacademy.com

 Before the recordBefore the record
bases werebases were
constructed, theconstructed, the
tuberosities weretuberosities were
outlined on the cast.outlined on the cast.
In these areasIn these areas
either type-3 goldeither type-3 gold
alloy or co-cr alloyalloy or co-cr alloy
was used aswas used as
denture basedenture base
material in place ofmaterial in place of
acrylic resin.acrylic resin.

3.J.Prosthet.Dent.3.J.Prosthet.Dent.
2004;92:128-31.2004;92:128-31.
Leonard Garth LoweLeonard Garth Lowe
presented a clinical reportpresented a clinical report
for the non surgicalfor the non surgical
management ofmanagement of bilateralbilateral
undercut in tuberosityundercut in tuberosity
region. They maderegion. They made
decision to incorporatedecision to incorporate
flexible flanges in theflexible flanges in the
undercuts using resilientundercuts using resilient
silicon lining materialsilicon lining material toto
allow adequate height andallow adequate height and
thickness of the denturethickness of the denture
flangeflange..

Sharp spiny processes-Sharp spiny processes-
 There are sharp spiny processes onThere are sharp spiny processes on
max. and palatal bone that are normallymax. and palatal bone that are normally
deeply covered by soft tissues but indeeply covered by soft tissues but in
patients with considerable RAR resorptionpatients with considerable RAR resorption
these processes irritate soft tissues .these processes irritate soft tissues .
 Canal leading from a posterior palatineCanal leading from a posterior palatine
foramen often has a sharp overhangingforamen often has a sharp overhanging
edge that may irritate palatal mucosa.edge that may irritate palatal mucosa.

Torus palatinus-Torus palatinus-
 Seen as a hard bony enlargement that occursSeen as a hard bony enlargement that occurs
in midline of the roof of mouth is called torusin midline of the roof of mouth is called torus
palatinus.palatinus.
 Seen in nearly 20% of populationSeen in nearly 20% of population
 2 types2 types
-almost entirely soft tissue, loose and flabby-almost entirely soft tissue, loose and flabby
- thin layer of mucosal tissue covering the bone- thin layer of mucosal tissue covering the bone
 Dentures require relief over this area to aidDentures require relief over this area to aid
retention and prevent soreness of the underlyingretention and prevent soreness of the underlying
tissues.tissues.

 A smoothA smooth
rounded smallrounded small
torus does nottorus does not
normally createnormally create
much problemmuch problem
as dentureas denture
plate may beplate may be
cut away tocut away to
avoid tori oravoid tori or
can becan be
extended overextended over
it with properit with proper
relief.relief.

 A large,A large,
irregular, lobbedirregular, lobbed
tori should betori should be
treatedtreated
surgically assurgically as
cutting away thecutting away the
denture platedenture plate
significantlysignificantly
reduces denturereduces denture
retention andretention and
also leads toalso leads to
excessive ridgeexcessive ridge
resorptionresorption..

Mandibular anatomicMandibular anatomic
landmarkslandmarks

Limiting structures-Limiting structures-
Labial frenum-Labial frenum-
• Is a fold of
mucous membrane
at the median line.
• It divides the labial
vestibule into left and
right labial vestibule.

 The mandibular labialThe mandibular labial
frenum contains afrenum contains a
band of fibrousband of fibrous
connective tissue thatconnective tissue that
helps to attach thehelps to attach the
orbicularis orisorbicularis oris
muscle.muscle.
 Therefore the frenumTherefore the frenum
is quite sensitive andis quite sensitive and
active, and theactive, and the
denture must bedenture must be
fitted carefully aroundfitted carefully around
it to maintain a sealit to maintain a seal
without causingwithout causing
soreness.soreness.

Labial vestibule-Labial vestibule-
 The labial
vestibule is divided
into left and right
labial vestibule by
the labial frenum.
• The mucous
membrane lining
the labial vestibule
is relatively thin
and is classified as
lining mucosa. www.indiandentalacademy.comwww.indiandentalacademy.com

 The muscles of the lowerThe muscles of the lower
lip pull actively across thelip pull actively across the
denture border, polisheddenture border, polished
surfaces, and teeth.surfaces, and teeth.
 When the patient’sWhen the patient’s
mouth opens wide, themouth opens wide, the
orbicularis oris muscleorbicularis oris muscle
becomes stretched,becomes stretched,
narrowing the sulcus.narrowing the sulcus.
 This would displace theThis would displace the
mandibular denture if themandibular denture if the
flange is unnecessarilyflange is unnecessarily
thick. Mandibular denturesthick. Mandibular dentures
and, hence, impressionsand, hence, impressions
will always be narrowest inwill always be narrowest in
the anterior labial region.the anterior labial region.www.indiandentalacademy.comwww.indiandentalacademy.com


The extent ofThe extent of
denture flange in thisdenture flange in this
region often is limitedregion often is limited
because of thebecause of the
muscles that aremuscles that are
inserted close to theinserted close to the
crest of ridge. Thecrest of ridge. The
mentalis muscle ismentalis muscle is
particularly active inparticularly active in
this region.this region.
Mentalis muscle
Origin – crest of ridge, Insertion –
chin
Action – raises the lower lip

 The tone of theThe tone of the
skin lower lipskin lower lip
and orbicularis orisand orbicularis oris
depends on thedepends on the
thickness of thethickness of the
flange and positionflange and position
of the teeth.of the teeth.

John L. ShannanJohn L. Shannan. The mentalis muscle in. The mentalis muscle in
relation to edentulous mandibles.relation to edentulous mandibles.
J Prosthet Dent.1972;27;477-484J Prosthet Dent.1972;27;477-484
 A study by dissecting 50 frozen cadavers,A study by dissecting 50 frozen cadavers,
the following observations were established.the following observations were established.
 The thinner the mandible in a superior-The thinner the mandible in a superior-
inferior direction, the nearer the origin of theinferior direction, the nearer the origin of the
mentalis muscle will be to crest of the residualmentalis muscle will be to crest of the residual
ridge.ridge.
 The origin of the mentalis muscle isThe origin of the mentalis muscle is
covered by the tissue (basal) surface of thecovered by the tissue (basal) surface of the
lower denture and that the mentalis muscle canlower denture and that the mentalis muscle can
complicate the development of the lower labialcomplicate the development of the lower labial
flange of lower complete dentures.flange of lower complete dentures.

 Space should be made in the labial flangeSpace should be made in the labial flange
of lower individualized impression trays toof lower individualized impression trays to
accommodate the mentalis muscle before theaccommodate the mentalis muscle before the
final impression is made.final impression is made.
 Each patient should be instructed toEach patient should be instructed to
elevate his chin and protrude his chin andelevate his chin and protrude his chin and
lower lip, as in pouting, during the primarylower lip, as in pouting, during the primary
impression-making procedures.impression-making procedures.
 The lower lip should not be mechanicallyThe lower lip should not be mechanically
elevated by the dentist, because this procedureelevated by the dentist, because this procedure
will not produce the same alteration in thewill not produce the same alteration in the
impression as the mentalis muscle will underimpression as the mentalis muscle will under
its own actionits own action

 Buccal frenum-Buccal frenum-
• The buccal frenum
forms the dividing line
between the labial
and buccal vestibule.
 Frenum may be
single or double,
broad U shaped or
sharp V shaped.

 Is an active frenum as
the fibres of the
triangularis, zygomaticus
and caninus muscles
converge here to form a
strong but movable base
from which the orbicularis
oris and buccinator may
operate as antogonists.
 It should be relieved to
prevent displacement of
the denture during
function.

Buccal vestibule-Buccal vestibule-
 The buccal vestibule extends posteriorly from
the buccal frenum to the outside back corner of the
retromolar pad.
 The buccal flange, which starts immediately
posterior to the buccal frenum, swings wide into the
cheek and is nearly at right angles to the biting force
 The impression is widest in this region.

 The extent ofThe extent of
buccal vestibule isbuccal vestibule is
influenced by theinfluenced by the
buccinator muscle,buccinator muscle,
which extends fromwhich extends from
the modiolusthe modiolus
anteriorly to theanteriorly to the
pterygomandibularpterygomandibular
raphe posteriorly andraphe posteriorly and
has its lower fibereshas its lower fiberes
attatched to theattatched to the
buccal shelf andbuccal shelf and
external obliqueexternal oblique
ridge.ridge.

 Extension ofExtension of
distobuccal border atdistobuccal border at
the end of buccalthe end of buccal
vestibule is influencedvestibule is influenced
by masseter muscleby masseter muscle
activity.activity.
 When the masseterWhen the masseter
contracts, it’s anteriorcontracts, it’s anterior
fibres alters the shapefibres alters the shape
and size of theand size of the
distobuccal end ofdistobuccal end of
lower buccal vestibulelower buccal vestibule
by pushing inwardby pushing inward
against the buccinatoragainst the buccinator
muscle and suctorialmuscle and suctorial
pad of fat.pad of fat. www.indiandentalacademy.comwww.indiandentalacademy.com

 Action of masseterAction of masseter
depends upon –depends upon –
1.1. origin of masseterorigin of masseter
on zygomatic archon zygomatic arch
 The distobuccalThe distobuccal
borders of mandibularborders of mandibular
denture must convergedenture must converge
rapidly to avoidrapidly to avoid
displacement bydisplacement by
contracting forces.contracting forces.
2.2. relative size of masseterrelative size of masseter
3.3. shape of the mandibleshape of the mandiblewww.indiandentalacademy.comwww.indiandentalacademy.com

Distal extension-Distal extension-
 The distal extension ofThe distal extension of
denture of denture isdenture of denture is
limited bylimited by
1.1. the ramus of mandiblethe ramus of mandible
2.2. by the buccinator muscleby the buccinator muscle
fibers and pterygo-fibers and pterygo-
mandibular raphemandibular raphe
3.3. superior constrictorsuperior constrictor
musclemuscle
4.4. lateral bony boundaries of retromolar fossaelateral bony boundaries of retromolar fossae
which are formed by continuation of intrenal andwhich are formed by continuation of intrenal and
external oblique ridgeexternal oblique ridge www.indiandentalacademy.comwww.indiandentalacademy.com

 Overextension of denture in thisOverextension of denture in this
region compresses these structuresregion compresses these structures
leading to soreness and compromisedleading to soreness and compromised
function of buccinator.function of buccinator.
 Desirable distal extension isDesirable distal extension is
slightly to these bony prominencesslightly to these bony prominences
and also includes retromolar pad areaand also includes retromolar pad area
to provide a soft tissue seal.to provide a soft tissue seal.

Retromolar pad-Retromolar pad-
 This is a triangular soft pad of tissues at the distalThis is a triangular soft pad of tissues at the distal
end of lower ridge.end of lower ridge.
Definition – “a mass
of tissue comprised of
non-keratinized
mucosa located
posterior to retromolar
papilla and overlying
loose glandular
connective tissue”.
GPT-8
 This freely movable area should be differentiated
from pear shaped pad.

 Pear shaped
pad- this is the
most distal
extension of
attached
keratinized mucosa
overlying the
mandibular ridge
crest formed by the
scarring pattern
after extraction of
most posterior
molar.

 The glandularThe glandular
retromolar padretromolar pad
is basically anis basically an
mandibularmandibular
extension ofextension of
palatal glandularpalatal glandular
mass.mass.

 Its mucosa isIts mucosa is
composed of a thin,composed of a thin,
nonkeratinizednonkeratinized
epithelium, and inepithelium, and in
addition to loose alveolaraddition to loose alveolar
tissue, its submucosatissue, its submucosa
containscontains
1.1. glandular tissue,glandular tissue,
2.2. fibers of the buccinatorfibers of the buccinator
and superior constrictorand superior constrictor
muscles,muscles,
3.3. the pterygomandibularthe pterygomandibular
raphe, andraphe, and
4.4. terminal part of theterminal part of the
tendon of the temporalistendon of the temporalis

 The action of these muscles limitsThe action of these muscles limits
the extent of the denture and preventsthe extent of the denture and prevents
placement of extra pressure on theplacement of extra pressure on the
distal part of the retromolar pad duringdistal part of the retromolar pad during
impression procedures, because ofimpression procedures, because of
this, the denture base should extendthis, the denture base should extend
approximately one half to two thirdsapproximately one half to two thirds
over the retromolar pad.over the retromolar pad.

Alveolingual sulcus-Alveolingual sulcus-
 This is the space between residualThis is the space between residual
ridge and tongue. It extends fromridge and tongue. It extends from
lingual frenum to retromylohyoidlingual frenum to retromylohyoid
curtain.curtain.
 Border is considered in followingBorder is considered in following
regions-regions-
- anterior region- anterior region
-middle region-middle region
-posterior region-posterior region

Anterior region-Anterior region-
 Extends fromExtends from
lingual frenum to thelingual frenum to the
point where mylohyoidpoint where mylohyoid
ridge curves aboveridge curves above
the level of sulcus.the level of sulcus.
 Here in this region aHere in this region a
depression, thedepression, the
premylohyoid fossaepremylohyoid fossae
can be palpated andcan be palpated and
correspondingcorresponding
eminenceeminence
premylohyoidpremylohyoid
eminence can be seeneminence can be seen
on impression.on impression.

 Anterior alveolingual sulcus of bothAnterior alveolingual sulcus of both
the sides together is called sublingualthe sides together is called sublingual
crescent space.crescent space.

Ligual frenum-Ligual frenum-
 It is a mucosal foldIt is a mucosal fold
which originates at thewhich originates at the
midline of undermidline of under
surface of the tonguesurface of the tongue
and often terminatesand often terminates
at the sublingualat the sublingual
salivary caruncles.salivary caruncles.
 In other instances, itIn other instances, it
crosses and bisectscrosses and bisects
the sublingualthe sublingual
crescent space andcrescent space and
attaches onto theattaches onto the
lingual aspect oflingual aspect of
mandibular ridge.mandibular ridge.

 Just beneath theJust beneath the
lingual frenumlingual frenum
genioglossus musclegenioglossus muscle
is found whichis found which
originates fromoriginates from
superior genialsuperior genial
tubercles.tubercles.
 It is a powerful andIt is a powerful and
active but fortunatelyactive but fortunately
narrow muscle.narrow muscle.
Anterior fibers of thisAnterior fibers of this
muscle when tensedmuscle when tensed
raises up from floorraises up from floor
of mouth and impingeof mouth and impinge
on lower dentureon lower denture
base.base.

Sublingual
folds –
 formed by
the superior
surface of the
sublingual
glands and
the ducts of the
submandibular
glands.

Middle region-Middle region-
 This region extends fromThis region extends from
premylohyod fosa to the distal end ofpremylohyod fosa to the distal end of
mylohyoid ridge.mylohyoid ridge.

 Mylohyoid muscleMylohyoid muscle
originates from wholeoriginates from whole
length of mylohyoidlength of mylohyoid
ridge. Mylohyoid ridgeridge. Mylohyoid ridge
runs obliquelyruns obliquely
downwards anddownwards and
forwards from belowforwards from below
the 3the 3rdrd
molar region tomolar region to
the median line belowthe median line below
genial tubercles but itgenial tubercles but it
is sharp and distinct inis sharp and distinct in
molar region andmolar region and
becomes almostbecomes almost
indiscernible anteriorly.indiscernible anteriorly.

 It is thin butIt is thin but
wide musclewide muscle
forming muscularforming muscular
floor of mouth.floor of mouth.
 Anteriorly fibresAnteriorly fibres
of mucle on eachof mucle on each
side join eachside join each
other mediallyother medially
and posteriorlyand posteriorly
they continue tothey continue to
hyoid bone to behyoid bone to be
inserted there.inserted there.
 Till premolar region muscle lies deep toTill premolar region muscle lies deep to
sublingual salivary gland, so does not effect denturesublingual salivary gland, so does not effect denture
borders except indirectly.borders except indirectly.www.indiandentalacademy.comwww.indiandentalacademy.com

 As we pass distally and reach molarAs we pass distally and reach molar
region mylohyoid ridge and attachedregion mylohyoid ridge and attached
muscle becomes quite superficial,muscle becomes quite superficial,
effect of mylohyoid muscle on lingualeffect of mylohyoid muscle on lingual
flange of denture is more pronouncedflange of denture is more pronounced
in this region than anterior region.in this region than anterior region.
 During swallowing mylohyoid muscleDuring swallowing mylohyoid muscle
contracts raising floor of mouth.contracts raising floor of mouth.

 In relaxed state mylohyoidIn relaxed state mylohyoid
muscle is a thin sheet ofmuscle is a thin sheet of
muscle and does not resistmuscle and does not resist
impresssion material so it isimpresssion material so it is
very easy to carry impressionvery easy to carry impression
material into the undercutmaterial into the undercut
below mylohyoid ridge. Thisbelow mylohyoid ridge. This
overextension can not beoverextension can not be
tolerated by tissues in function.tolerated by tissues in function.
 Lingual flange should beLingual flange should be
made to slope towards themade to slope towards the
tongue, parallel to mylohyoidtongue, parallel to mylohyoid
muscle when it is contracted,muscle when it is contracted,
well beyond the palpablewell beyond the palpable
portion of mylohyoid ridge butportion of mylohyoid ridge but
not in the undercut.not in the undercut.

 When middle ofWhen middle of
lingual flange is made tolingual flange is made to
slope towards theslope towards the
tongue, it can extendtongue, it can extend
below the level ofbelow the level of
mylohyoid ridge. Thismylohyoid ridge. This
way tongue rests on theway tongue rests on the
top of flange and aids intop of flange and aids in
stabilizing it. In additionstabilizing it. In addition
this slope providesthis slope provides
space for floor of mouthspace for floor of mouth
to be raised duringto be raised during
function withoutfunction without
displacing the denture.displacing the denture.

 When the mylohyoid muscle is relaxedWhen the mylohyoid muscle is relaxed
there is space between the flange and floorthere is space between the flange and floor
of mouth but contact is reestablished whenof mouth but contact is reestablished when
the floor of mouth is raised.the floor of mouth is raised.
 If lingual border stops above theIf lingual border stops above the
mylohyoid ridge, border seal can not bemylohyoid ridge, border seal can not be
achieved and also vertical forces will causeachieved and also vertical forces will cause
soreness at the mylohyoid ridge.soreness at the mylohyoid ridge.

Posterior region-Posterior region-
 Here the flangeHere the flange
passes intopasses into
retromylohyoid space.retromylohyoid space.
This is pouch shapedThis is pouch shaped
area is posterior toarea is posterior to
mylohyoid musclemylohyoid muscle
attachment.attachment.
 Term retromylohyoidTerm retromylohyoid
space was given byspace was given by
Edward and BoucherEdward and Boucher
in 1942.in 1942.

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