Land marks / dental implant courses by Indian dental academy

DENTURE BEARINGDENTURE BEARING
AREAS.AREAS.
INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMY
Leader in continuing Dental EducationLeader in continuing Dental Education
www.indiandentalacademy.com

INTRODUCTION :
MAXILLARY & MANDIBULAR EDENTULOUS FOUNDATIONS:
Knowledge of oral anatomy helps the operator in understanding the
landmarks that serve as positive guides in Prosthodontic procedures
.
DEFNATION:Denture bearing areas or Denture foundation area or Basal
seat —the surface of the oral structures available to support a
denture.(GPT-8)
Denture bearing area- maxilla 24 cm2
& mandible 14 cm2
(Dr WATT
surgeon.)
The impression surface/Fitting surface-
1.stress-bearing/supporting areas.
2.peripheral/limiting areas.

STRESS-BEARING
AREA.
• PRIMAY.
• Hard palate.(max)
• Buccal shelf.(man)
• SECONDARY.
• Rugae.(max).
• Slopes of residual
ridge.(man).

Supporting areas.
• PRIMAY.
• Horizontal portion
of Hard palate.
(max)& Rugae
• Buccal shelf (man)
• SECONDARY.
• Crest of residual
ridge.(max)
• Slopes of residual
ridge.(man)

RETENTIVE FACTORES.

RELIEF AREAS.
• MAXILLA.
• Medial palatal
suture.
• Incisive foramen.
• Sharp boney
projection.
• Rugae – valley.
• MANDIBLE.
• Crest of residual
ridge.
• Sharp boney
projection.
• Mental foramen.
• Genial tubercle.
• Mylohyoid ridge.

Labial frenum:
• Fold of mucous membrane
at the median line.
• Moves with muscles of lip.
• Adequate relief for muscle
activity.
• Proper denture seal.
• Excessive relief weakens
denture base.
Maxillary arch
•A- correct
contour
•B –incorrect
contour.
•C- area
should have
been covered.
Labial notch

Buccal frenum:
 Single or double folds of
mucous membrane.
 Broad and fan shaped.
 Moves with muscles of
cheek during speech and
mastication.
 Adequate relief for muscle
activity-more clearence.
•Maxillary buccal frenum area.
•Denture border contour in buccal
frenum area.
Buccal notch

Labial vestibule
• Labial-buccal frenum.
• Muco-gingival line-
limits upper border.
• Record adequate
depth/width.
• Overextension causes
instability/soreness.
• Proper contouring
gives optimal
esthetics.
•Labial flange

Buccal vestibule
• Buccal frenum to
hamular notch.
• Record adequate
depth/width.
• Improper extension
causes
Buccal flange

Maxillary tuberosity.
• Distal end of
denture must have
Coverage-
stability/retention.
• Gross
enlargement(fibrou
s or bony –surgical
correction.
Area of tuberosity

•Distal to maxillary
tuberosity
•Aids in locating
posterior palatal seal.
•Overextension causes
soreness.
Hamular notch.
Area of hamular notch

PPS-the seal area at the posterior border of a maxillary
removabledentalprosthesis.(GPT-8)
PPS OR POST PALATAL SEAL 0R POST DAM-
The soft tissue along the junction of the hard and soft
palates on which pressure with in the physiologic limits of the
tissues can be applied by a denture to aid in the retention of
the denture. (Winkler)
• VIBERATING LINE-an imaginary line across the posterior part of
the palate marking the division between the movable and
immovable tissues of the soft palate. this can be identified when
the movable tissues are functioning.
• The anterior vibrating line is an imaginary line located at the
junction of the attached tissues overlying the hard palate and
movable tissues of the immediately adjacent soft palate.(valsalva
maneuver –method)
• The posterior vibrating line is an imaginary line at junction of the
aponeurosis of the tensor veli palatini muscle and the muscular
portion of the soft palate.

Vibrating line:
• Junction of movable and
immovable part of soft
palate.
• 2mm ant to fovea palatinae.
• Aids to establish PPS.
• Distal end of denture at
least to vibrating line.
Post palatal seal area.
• From hamular notch to
hamular notch.
• Anterior to vibrating line.
• Aids in retention.
.

SHAPES OF PPS.
• FUNCTION OF PPS.
• ANATOMY OF PPS.
• TECHNIQUES.

Fovea Palatinae.
• Bilateral indentations
near the midline of
palate.
• Formed by coalescence
of several mucous gland
ducts.
• Posterior to junction of
hard and soft palate.
• Aids in determining
vibrating line.

Hard palate
• Support for the
maxillary denture.
• Primary stress
bearing area-
horizontal portion
of hard palate
lateral to midline.
• Secondary stress
bearing area –
rugae.www.indiandentalacademy.com

Alveloar ridge
• .
Alveolar groove

• Elevation of soft
tissue over the incisive
foramen or
nasopalatine canal.
• Location : on or labial
to ridge.
• Impingement –burning
sensation, parasthesia
and pain.
• Relief necessary.
Incisive papilla.
•Incisive fossa

Rugae.
• Irregular shaped
rolls of soft tissue.
• Secondary stress
bearing area.
• Should not be
distorted in the
impression.

• Extends from incisive
papilla to distal end of
hard palate.
• Thin mucosal covering
and non-resilient..
• Relieve adequately to
avoid trauma from
denture base.
Median palatine raphae.
Median palatine groove

Labial frenum.
• Shorter and wider
than the maxillary
frenum.
• Adequate relief for
muscle activity
(mentalis).
• Proper fit around it
maintains seal’.
Mandibular arch.
Labial notch.

Buccal frenum.
• Adequate relief
for muscle
activity.
• Proper denture
seal.
Buccal notch.

Labial vestibule.
• Labial-buccal frenum.
• Muscles attachment
close to the crest of
the ridge- limits the
denture flange
extension.
• Mucolabial fold limits
the depth of the
flange.
• Record adequate
depth and width.
• Proper contouring
gives optimal
esthetics.
Labial flange

Buccal vestibule.
• Buccal frenum-
retromolar pad.
• Record adequate
depth and width.
• Impression is
widest in this area.
Buccal flange

Buccal shelf
• .

Def..Anatomically buccal shelf is defined as the part of the basal
seat located posterior to the buccal frenum.(Boucher 10th
edition).
• The area between the mandibular buccal frenum and the anterior
edges of masseter muscle is known as buccal shelf(b12)
Boundaries:
• Anteriorly-buccal frenum.
• Posteriorly-retromolar pad.
• Medially-crest of the ridge
• Laterally-external oblique ridge.
Width-4-6 mm wide on average mandible.
• 2-3 mm or less in narrow mandible.
• The total widthof the bony foundation in this region becomes
greater as alveolar bone resorption continues.the reason is that
the inferior border of the mandible is great than the width at the
alveolar process.
Clinical implication: upper slopes of the buccal shelf adjacent to the
pad helps to resist the distal dis placement of the denture
because of the diminished available support,a narrow mandible is
usually considered the most difficult to manage.
• Clinically care should be taken to cover the area

• Interpreting the buccal shelf area:While
recording the final impression additonal load is
applied in this area,the trays comes in to direct
cotact with the mucosa.
• Preprosthetic surgery:no
• When the residual ridge becomes flat the
buccinator is often attached to the center of the
ridge.the buccinator muscle can be covered by
the denture in this area because the muscle
fibres run anterioposteriorly parallel to the bone
and the denture does not resist the contracting
forces of the muscles.the inferior part of the
buccinator is attached to the buccal shelf of the
mandible and the contraction of the muscle
doesnot lift the denture.(resorbtion
• Resisted by horizontal fibres of buccinator

Histology: mucous membrane-is more loosely
attached and less keratinised than the mucous
membrane covering the crest of the ridge.
• Submucosa:thicker,fibres of buccinator are
found running horizontally in the submucosa
immediately overlying the bone.
• The mm overlying the buccal shelf may not be
suitable histologically to provide primary support
for the denture as the mm overlying the crest of
the ridge.
• Bone:bs is covered by layer of smooth compact
boneor cortical bone(with it’s haversian
system,the bone is very dense and the trbaculae
are arranged almost at right angles to the jaw
closure) plus the fact that the bucal shelf lies at
right angles to the vertical occlusal
forces,therfore it is more suitable primary stress
bearing area for the lower denture.

• Blood supply—artery supply—buccal
artery,inferior alveolar artery,nerve supply—
buccal nerve ,inferior alveolar nerve,buccal
branch of mandibular nerve.
• Oralucousmembrane thick ness--mucous
membrane-is more loosely attached and less
keratinised than the mucous membrane covering
the crest of the ridge.
• Muscle found in this area—inferior part of the
buccinator,anterior edge of the masseter muscle.

External oblique ridge.
• A bony ridge runs
antero-posteriorly
outside the buccal
shelf.
• Denture border 1-2
mm beyond this ridge.
• Shows as Groove in
impression.

Alveolar ridge
• Residual bone with
mucous membrane.
• Crest to be
relieved.
• Buccal and lingual
slopes are
secondary stress
bearing areas.

RRR-A Term used for the dimnishing quantity and
quality of the residual ridge after teeth are removed.
(GPT-8)
 PATHOLOGY.-A Frequent lay expression for RRR is “my
gums have shrunk.” the basic structural change in the
residual ridge is the reduction in the size of the bone ridge
under the muco periostium.it is primarily a localized loss of
bony structure. maxillary denture area of 4.2in2
. Mandibular
denture area is 2.3in 2
(ratio 1.8;1). .
 1.Main factor in RRR is the cicatrizing mucoperioteum that
is seeking a reduced area, resulting in pressure resoption of
the under lying bone.
 2. the lateral cephalogram has clearly shown the gross
reduction of bone in size and shape that occurs on the
external surface on the labial ,crestal ,and lingual aspects
of the RRR.
• . www.indiandentalacademy.com

 SIX ORDERS OF MANDIBULAR ANTERIOR RESIDUAL RIDGE
FORM:
ORDER 1 PRE EXTRACTION.
ORDER 2 POSTEXTRACTION.
ORDER 3 HIGH,WELL ROUNDED
ORDER 4 KNIFE EDGE (as the resorption continuous from labial
And lingual aspect ,the crest of the residual ridge becomes
increasingly narrow ,ultimately becoming knife edge .)
ORDER 5 LOW WELL ROUNDED
ORDER 6 DEPRESSED.
 The most accurate method for determing ;
Amount of RRR +rate of RRR/over a period of time
 Clinically ,the soft tissue overlying the RR that have undergone
RRR may range from normal to inflamed ,edematous ,ulcerated
,indented or abused tissues.
 Microscopic pathology reveal an evedent of osteoclastic activity on
the external surface of RR.

• FACTORES.1.Anotomic factors-it is postulated that RRR
varies with quality and quantity of the bone i.e RRR is
directly proportional to anatomical factors.
• 2. metabolic factor –it is further postulated that RRR
varies directly with certain systemic or localized bone
resorptive factors and invasively with certain bone
formation factor.
• 3.Mechanical factor-the remodeling of bone is influenced by
force factors. bone that is “used” as by regular physical
activity will tend to strengthen with in certain limits, while
bone that is in “disuse” will tend to be atrophy.
• In considering the force- the amount of force, duration of
the force, direction of force and frequency of force the
area over which force is distributed (force per unit area)
and the damping effect of the underlying tissue all these
should be considered for RRR.

Retromolar pad.
• Triangular soft pad of tissue.
• Posterior end of lower
edentulous ridge.
• Limiting landmark of distal
extension of complete denture
upto ant 2/3 rd of retro molar
pad.
• Determines height and width
of the occlusal table.
• Contents-loose connective
tissue, glandular tissue
,laterallybuccinator,posteriorly
temporalis tendon, medially
superior constrictor and
pterygo mandibular raphe
• gritman carver
Retromolar fossa

Alveolo-Lingual sulcus.
• Between lingual frenum to
retromylohyoid curtain.
• Anterior region-
• Premylohyoid fossa-
premylohyoid eminence in
impression.
• Border of Impression to make
contact with the mucosa of
the floor of the mouth when
tongue touches the upper
incisor.
soreness and instability.
Lingual flange
Premylohyoid
eminence

Middle region.
• From pre-mylohyoid fossa to
the distal end of the
mylohyoid ridge.
• Lingual flange extends below
the level of the mylohyoid
ridge- tongue rests on the
top of flange and aids in
stabilizing the lower denture.
• To record ask the patient to
touch the buccal mucosa on
either side of cheek with tip
of the tongue.

Posterior region.
• The flange
passes into the
retromylohyoid
fossa.
• Proper
recording gives
typical S –form
of the lingual
flange.

Retromylohyoid fossa.
• Distal end of lingual
sulcus.
• Area posterior to
the mylohyoid
muscle.
• Good seal aids in
retention and
stability.
• To record –ask the
patient to protrude
the tongue
Retromylohyoid eminence

BOUNDARRIES OF LATERAL THROAT
FORM.
• Anteriorly –myelohyoid muscle
• Laterally –pear shaped pad
• Posteriolaterally-superior constrictors and
• Posteromedially –palatoglossus
• The posterior limit of the mandibular
denture is determined mainly by the
palatoglossal muscle and by superior
constrictor muscle-this area is called as
retro myelohyoid curtain.

Mylohyoid ridge.
• Attachment for the
mylohyoid muscle.
• Sharp or irregular
covered by the mucous
membrane.
• Trauma from denture
base –relief necessary.

Mylohyoid muscle.
• Floor of the mouth is
formed by mylohyoid
muscle.
• Lies deep to the
sublingual gland in
the anterior region-
does not affect the
border of denture.
• Posterior region –
affects the lingual
border in swallowing
and tongue
movements.

Genial tubercle.
• Area of muscle
attachment (Genioglossus
and Geniohyoid).
• Lies away from the crest
of the ridge.
• Prominent in Resorbed
ridges.
• Adequate relief to be
provided.

Lingual frenum.
• Fold of mucous
membrane.
• Base of tongue to
supragenial
tubercle.
• Registered in
function.
Lingual notch

BIBLIOGRAPHY
1.Text book of complete denture.
-Hartwell 5th
edition.
2.Prosthodontic treatment for edentulous patient.
-Boucher9th
,10th
,12th
edition.
3.Essentials of complete denture prosthodontics
-Winkler 2nd
edition.
4. Impressions for complete denture.
- bernard levin.

CONCLUSION.
• The denture should cover the maximum
surface area as possible within the limits
of health and function of tissues. We the
prosthodontist should have a thorough
knowledge of basal seat and limiting
structure for a successful functioning of
prosthesis and preservation of tissues.

Land marks / dental implant courses by Indian dental academy

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