Anatomy

Anatomy
Wednesday, March 5, 2008
“ ”
Anatomy
If dentures and their supporting
tissues are to coexist for a
reasonable length of time, the
dentist must fully understand
the anatomy of the supporting
and limiting structures
involved, for these are the
foundation of the denturebearing area.
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Anatomy
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Anatomy
“ ”
The amount of biting force an edentulous ridge will tolerate
The denture base must
extend as far as possible
without interfering in the
health or function of the
tissues.
is directly proportional
to the amount of surface area covered
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Anatomy
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Anatomy
Force directed to a large bearing area is more equally
distributed and much less per sq. mm. than the same force
directed against a smaller area.
F
Consequently, if we hope to assist a patient to achieve
maximum biting force and preserve the supporting
structure over a longer period of time,
F
The maximum amount of denture bearing
area must be covered.
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Anatomy
Anatomy
Are all the supporting tissues the same ?
Are all the supporting tissues the
same ?
Macroscopically (Residual Ridges, Palate)
Microscopically
(Mucous Membrane)
NO !
"

Mucosa + Submucosa
"
Too thin =

Too loose, inflamed, or edematous =
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Anatomy
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Anatomy
What defines the maximum amount of bearing area ?
The
LIMITING
- OR PERIPHERAL TISSUES
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Anatomy
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Anatomy
LF
LV
IP
CE
BF
MS
AR
BV
PPB
AT
MT
FP
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ZA
VL
JHSP
PR
HN
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Anatomy
Anatomy
Li
F
A-L S
BV
BF
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Anatomy
Buccal Shelf
Anatomy
LaV
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Anatomy
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LaF
Retromylohyoid
Space - Lateral
Throat Form
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Anatomy
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Anatomy
Anatomy
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Anatomy
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Anatomy
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Anatomy
TEMPORALIS
MUSCLE
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Anatomy
MASSETER
MUSCLE
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Anatomy
Anatomy
Are these tissues all equal
in their capability to
support a denture under
pressure?
(1) Primary stress bearing area,
(2) Relief area
NO !
(3) Peripheral seal area
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Anatomy
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Anatomy
Relief area
Primary stress bearing area
Pressure causes discomfort to the patient
Best to resist vertical forces of occlusion
Pressure causes instability of the denture base
Base of cortical bone
Protected by firmly attached epithelial type tissue
Sufficient thickness to form a cushion against the forces
of occlusion.
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Anatomy
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Anatomy
Stress
Bearing
Peripheral seal area
Soft tissue border areas, which the periphery of the
denture must contact in order for the factors of retention
to be effective.
Ridge Crest
Lateral Hard Palate
The peripheral seal area is divided into two parts:
(1) Resistant peripheral area
Ridge Crest
Buccal Shelf
(2) Nonresistant peripheral area
Retromolar Pads
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Anatomy
Anatomy
Relief
Areas
Resistant Peripheral Areas
Papilla
Zygomatica
Suture
Mylohyoid Ridge
Mental Foramen
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Anatomy
Resistant Peripheral Areas
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Anatomy
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Anatomy
Resistant Peripheral Areas
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Resistant Peripheral Areas
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Anatomy
Resistant Peripheral Areas
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Anatomy
Resistant Peripheral Areas
Anatomy
Maxillary Resistant Peripheral Areas
Hamular Process of the
Medial Pterygoid Plate
Lip
Hamular Process of the
Medial Pterygoid Plate
Lip
Mucosa
Alveolar
Bone
Tuberosity
Hamular Notch
Mucosa
Alveolar
Bone
Tuberosity
Hamular Notch
Pterygomandibular
Raphe
Pterygomandibular
Raphe
Retromolar Pad
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Anatomy
Resistant Peripheral Areas
Anatomy
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Non-Resistant Peripheral Areas
It is imperative that all maxillary denture
bases terminate in this notch.
Bases short of the hamular notch will
end on the thin - nonflexible - tissue
of the tuberosity and will
consequently lack retention.
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Anatomy
Non-Resistant Peripheral Areas
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Anatomy
Non-Resistant Peripheral Areas
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Anatomy
Non-Resistant Peripheral Areas
Anatomy
Alveolar
Process
Hard Palate
Posterior Limit
of Hard Palate
Soft Palate
Lip
Labial
Vestibule
Mucosa
Vibrating Line
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Anatomy
Non-Resistant Peripheral Areas
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Anatomy
Non-Resistant Peripheral Areas
Classifications of Throat Form
CLASS I
6 - 8 mm of soft palate extends beyond the hard
palate before dropping downward or registering
movement when the patient speaks
CLASS II
3 - 4 mm
CLASS III
0 mm
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Anatomy
Non-Resistant Peripheral Areas
CLASS III
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Anatomy
AHH
Non-Resistant Peripheral Areas
CLASS III
AIR
Lip
Vibrating Line
For the Class III throat form where the movement of the soft
palate starts immediately at the posterior border of the hard
palate, problems may be encountered in establishing a good
seal.
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Lip
For the Class III throat form where the movement of the soft
palate starts immediately at the posterior border of the hard
palate, problems may be encountered in establishing a good
seal.
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Anatomy
AHH
Anatomy
Non-Resistant Peripheral Areas
Mandibular Peripheral Areas
Resistant Peripheral Areas
CLASS III
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AIR
Lip
1.Labial frenum
2.Buccal frenum
3.Distobuccal arch
4.Pterygomandibular raphe
5.Retromylohyoid curtain
6.Alveolo-lingual fold
7.Lingual frenum
Nonresistant border areas
8.Labial vestibule
9.Buccal vestibule
For the Class III throat form where the movement of the soft
palate starts immediately at the posterior border of the hard
palate, problems may be encountered in establishing a good
seal.
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Anatomy
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Anatomy
Mandibular Peripheral Areas
3.Distobuccal arch
4.Pterygomandibular raphe
5.Retromylohyoid curtain
Mandibular Peripheral Areas
3.Distobuccal arch
4.Pterygomandibular raphe
5.Retromylohyoid curtain
Posterior Limit of the Lower Denture
The distobuccal arch is under the control of the masseter muscle
which has its origin at the zygomatic arch. It is attached to the
lateral border of the mandibular ramus. Dentures, which are
overextended in this area, interfere with the contraction of the
masseter muscle, which pushes forward against the buccinator
muscle creating discomfort when the patient closes. The
distobuccal arch flange, if properly shaped, will usually run at a
45-degree angle from the mesiobuccal arch to the apex of the
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retromolar pad.
Anatomy
Mandibular Peripheral Areas
3.Distobuccal arch
4.Pterygomandibular raphe
5.Retromylohyoid curtain
Distolingual Extension of the Lower Denture
The retromylohyoid curtain lies lingual and inferior to the retromolar
pad. It is formed by the mucous membrane of the lingual lateral border
of the mandible and is attached to the posterior sides of the tongue. Its
size, shape, and position vary with tongue movements. The curtain
moves upward and backward as the tongue moves upward and
backward in swallowing. It moves upward and forward during
protrusive and lateral movements of the tongue. The amount of
upward and forward movement of the curtain during these protrusive
and lateral movements is referred to as the lateral throat form of the
mandibular denture. If this movement is slight and the angle formed by
the posterior part of the curtain to the retromolar pad is approximately
90 degrees, it is a Class I throat form. Extreme forward movement of
the curtain resulting in an angle of 45 degrees or less in Class III throat
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form and in between the two is Class II throat from
The pterygomandibular raphe forms the attachment
of the superior constrictor to the buccinator muscle.
It runs from the posterior border of the hamular
notch downward to the apex of the retromolar pad.
The raphe stretches when the mouth is opened,
pulling the distal edge of the pad upward. Dentures
should not extend beyond this line of movement.
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Anatomy
Mandibular Peripheral Areas
3.Distobuccal arch
4.Pterygomandibular raphe
5.Retromylohyoid curtain
The amount of posterior lingual extension of the base is controlled by the
movement of this curtain. Overextension of the denture flange results in
the patient complaining of a sore throat or unseating of the denture.
Underextension handicaps the tongue in controlling the lower denture
and allows ingress of food under the denture. This tissue offers very little
resistance to pressure so the operator must be careful not to create a
false undercut by displacing it when making the impression.
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Anatomy
MEDIAL PTERYGOID
Mandibular Peripheral Areas
MASSETER
SUPERIOR
CONSTRICTOR
PTERYGOMANDIBULAR
RAPHE
B
U
C
C
I
N
A
T
O
R
Palatoglossus
Superior
Constrictor
Mylohyoid
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Anatomy
Anatomy
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Anatomy
Mandibular Peripheral Areas
Mandibular Peripheral Areas
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Anatomy
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Anatomy
Mandibular Peripheral Areas
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A
Mandibular Peripheral Areas
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A
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Anatomy
3.Distobuccal arch
4.Pterygomandibular raphe
5.Retromylohyoid curtain
6.Alveolo-lingual fold
The mylohyoid muscle originates at the mylohyoid ridge.
Its fibers pass downward and inward and are inserted
posteriorly to the hyoid bone - and anteriorly, with its
neighbor, form the opposite side at the median raphe.
Lingual Extension of the Denture
The alveololingual fold is formed by the mucous
membrane's attachment to the lingual side of the mandible
laterally and its attachment to the lateral borders of the
tongue lingually. Because of this attachment, the fold is
elevated when the tongue is protruded or when the tongue
is moved laterally. Supporting the mucous membrane and
forming the floor of the mouth is the mylohyoid muscle
posteriorly and the sublingual gland anteriorly.
Anatomy
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Anatomy
The mylohyoid muscle originates at the mylohyoid ridge.
Its fibers pass downward and inward and are inserted
posteriorly to the hyoid bone - and anteriorly, with its
neighbor, form the opposite side at the median raphe.
Denture Base
Mylohyoid
Buccinator
Mandible
3rd Molar Region
1st Molar Region
Anatomy
Premolar Region
Canine Region
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Anatomy
The mylohyoid muscle, along with the mucous membrane can
easily be displaced by pressure. Overextended bases in this lingual
area will cause the denture to either lift out of position or result in a
denture injury.
For this reason it is necessary that an accurate non‑pressure
impression be obtained of the functional range of the fold.
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Anatomy
Anatomy
Below the sublingual gland are the mylohyoid muscles, and when
this muscle raise upon swallowing it forces the gland and the floor
of the mouth upward. Therefore, this is a resistant border area,
and extension of the base is limited to the functional position of
these tissues.
Below the sublingual gland are the mylohyoid muscles, and when
this muscle raise upon swallowing it forces the gland and the floor
of the mouth upward. Therefore, this is a resistant border area,
and extension of the base is limited to the functional position of
these tissues.
Vibrating Line
Hard Palate
Soft Palate
Bolus
ESOPHAGUS
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Forms  & A should be completed by the
end of today’s lab session and placed in the
white envelope designated for each bench. 76
What’s our job?
Impressioning
Thanks
March 3 & 5, 2008
Take a little break and head to
lab.
5910 LAB
This week’s GOALS:
Maxillary and mandibular casts
mounted on your Hanau H-2
articulator
&
Minimum of one pair of
baseplates with occlusion rims.
The faculty will be out on the floor
after we have a short meeting.
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For next week March 10 & 12
5910 LAB
GOALS:
Set maxillary and
mandibular denture
teeth with a
lingualized occlusal
scheme.
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