Complete denture theory and practice 2011.

COMPLETE DENTURE
THEORYAND PRACTICE
Mostafa Fayad
Lecturer of Removable Prosthodontic
Faculty Of Dental Medicine
Al-Azhar University
Cairo- Egypt
2011
2nded

COMPLETE DENTURE THEORY AND PRACTICE
Dr.mostafa.fayad@gmail.com
Table of contents
Subjects
1 introduction
2 Anatomy and Physiology in Complete Denture
3 diagnosis
4 Impression Trays and techniques
5 Relief Areas and post dam
6 Record Base and occlusion rim
7 JAW RELATION
8 Occlusion & articulators
9 SELECTION , arrangement of artificial teeth and WAXING-UP
10 try in
11 Processing Dentures
12 Denture insertion
13 Complaints
14 SEQUALAE OF WEARING CD
15 PREPARATION OF THE MOUTH
16 Management of Problematic patients
17 FAILURE OF C. D
18 Nausea & gagging
19 SINGLE COMPLETE DENTURE
20 Combination syndrome
21 TEETH supported OVERDENTURE
22 Implant Overdentures
23 Geriatric Edentulous Patient
24 Duplication
25 Relining and rebasing
26 Repair
27 Biomechanics
28 Neutral Zone
29 Esthetics in Complete Denture
30 phonetics in Complete Denture
31 masticatory function
32
33

COMPLETE DENTURE THEORY AND PRACTICE Introduction to CD 1
Dr.mostafa.fayad@gmail.com 1
Introduction
Prosthetics : It is the art and science of designing, supplying and fitting artificial replacement for
missing part of the human body.
Prosthesis : Is the artificial appliance which replaces a lost part of the human body.
Prosthodontics: It is a branch of dental science which deals with replacement of missing teeth
and associated structures by using artificial devices to restore function and esthetics.
Prosthodontics
1- Fixed prosthodontics.
2- Removable prosthodontics : a- complete denture b- partial denture
3- Maxillofacial prosthodontics.
Removable Prosthodontics is the art and science of replacement of missing teeth and oral
tissues with a prosthesis designed to be removed by the wearer. It includes removable complete
and removable partial prosthodontics.
Dentulous : A condition in which natural teeth are present in the mouth.
Edentulous : A condition in which all natural teeth are lost.
Partially Edentulous : A condition in which some of the natural teeth are lost.
Retention is a quality inherent in a prosthesis acting to resist dislodging forces along the path
of placement.
Stability is the quality of prosthesis to be firm, steady, or constant, to resist displacement by
functional horizontal or rotational forces.
Support is the quality of prosthesis to resist vertical tissue ward force.
Supporting area is the foundation area on which a dental prosthesis rests.
Complete Denture Prosthodontics : It involves the replacement of the lost natural dentition and
associated structure of the maxilla and mandible for patients who have lost all their natural teeth.
Objectives of Complete Denture Prosthodontics
1- Restoration of the masticatory function.
2- Restoration of the normal appearance.
3- Correction of speech defects resulting from loss of natural teeth.
4- Preservation of the alveolar bone and tempromandibular joints.
5- Satisfaction and comfort of the patient .

Denture surfaces
Complete denture consists of denture base that rest on the supporting structure and to
which an artificial teeth attached to it.
It has three surfaces:
1-Fitting surface, (intaglio surfaces, impression surface) determined by the impression.
2-Polished surface; includes the facial (labial and buccal) and lingual and palatal
surfaces.
3-Occlusal surface that makes contact with the opposing denture.
Denture borders: The margin of the denture base at the junction of the polished and
impression surface.
Denture flanges
The vertical extension of the denture base that extends from the cervix of the teeth to the
borders of the denture flanges; they are named according to location into:
Labial flange; the portion of flange that occupies the labial vestibule.
Buccal flange; the portion of flange that occupies the buccal vestibule.
Lingual flange; the portion of mandibular denture flange that occupies the alveololingual
sulcus.

The differences between natural teeth and artificial teeth
Natural Teeth Artificial Teeth
Type of support
The teeth are supported by periodontal tissue
which gives support, positional adjustment of
teeth and proprioceptive response.
Area of support in both jaws
About 90 cm square.
Amount of masticatory forces
From 5 - 17.5 pounds.
Effect of masticatory forces
The masticatory forces are transmitted to the
bone in the form of tension through the
periodontal ligament. This tension is well
accepted by the alveolar bone and may even
service as stimulus for alveolar bone remolding
Effect of pressure on teeth
Each tooth receives individual pressure and
moves independently.
Effect of non-vertical components of forces
Well tolerated.
Incising forces
Not affect posterior teeth.
Proprioceptive response
The proprioceptive mechanism act as a useful
alarm protecting both the supporting structures
of the tooth and the substance of the crown
from the effects of excessively vigorous
masticatory movements.
All teeth are on bases and supported by mucosa
which is not created to be covered.
About 35 cm square of edentulous mouth.
About 10- 15% of its value in natural dentition.
The force is not directed to the entire alveolar
bone but is applied only on its surface in the
form of compression. This compression has
limited tolerance by the bone and may cause
alveolar bone resorption.
Teeth move as a unit on a base.
Cause trauma to the supporting tissue and
reduce stability to the denture.
Cause tipping of the denture base specially if
the teeth are not balanced articulated.
By the loss of natural teeth there is no
proprioceptive mechanism.

Steps of Complete Denture Construction
Clinical Steps Laboratory Steps
1-History taking and examination of the
mouth.
-Preparing the mouth for dentures.
2-Taking of preliminary impressions
(in stock trays)
5-Taking of final impressions (in special
trays) and determining of the posterior
palatal seal.
8-Recording of jaws relations, face bow
transfer and selection of teeth.
11-Trying in the waxed denture.
15-Registration of new centric relation and
face bow transfer for clinical remount
(if needed).
17-Delivery of the finished denture and
instruction for their use.
18-Review of the denture (inspection and
aftercare).
3-Casting of the preliminary impression (using
plaster of paris).
4-Construction of special trays.
6-Boxing in and casting of the final impression
(using dental stone).
7-Construction of occlusion record blocks.
9-Mounting of the casts with the record blocks
on the articulator.
10-Setting-up of the teeth and waxing-up.
12-Processing of the denture (flasking, wax
elimination, packing, curing and
deflasking).
13-Laboratory remounting of the denture and
correction of occlusion by selective
grinding.
14-Finishing and polishing.
16-Remount of the denture on articulator for
adjustment of occlusion (if needed).

Classification System for Complete Edentulism
 The American College of Prosthodontists has developed a classification system for
complete edentulism based on diagnostic findings. These guidelines may help
practitioners determine appropriate treatments for their patients. Four categories are
defined, ranging from Class I to Class IV, with Class I representing an uncomplicated
clinical situation and a Class IV patient representing the most complex and higher-risk
situation.
 Each class is differentiated by specific diagnostic criteria. This system is designed for use
by dental professionals who are involved in the diagnosis of patients requiring treatment
for complete edentulism.
Potential benefits of the system include:
1)better patient care,
2) improved professional communication,
3) more appropriate insurance reimbursement,
4) a better screening tool to assist dental school admission clinics, and
5)standardized criteria for outcomes assessment.
Diagnostic Criteria
The diagnostic criteria used in the classification system are.
1. Bone height--mandibular
2. Maxillomandibular relationship
3. Residual ridge morphology maxilla
4. Muscle attachments
Bone Height: Mandible only
 The results of a radiographic survey of residual bone height measurement are affected by
the variation in the radiographic techniques and magnification of panoramic machines of
different manufacturers.
 To minimize variability in radiographic techniques, the measurement should be made on
the radiograph at that portion of the mandible of the least vertical height.

A measurement is made and the patientis classified as follows:
 Type I (most favorable): residual bone height of 21mm or greater measured at the least
verticalheight of the mandible
 Type II: residual bone height of 16 to 20 mmmeasured at the least vertical height of the
mandible
 Type III: residual alveolar bone height of 11 to 15mm measured at the least vertical
height of the mandible
 Type IV: residual vertical bone height of 10 mm or less measured at the least vertical
height of the mandible
The continued decrease in bone volume affects:
1) denture-bearing area;
2) Tissues remaining for reconstruction;
3) Facial muscle support/attachment;
4) Total facial height; and
5) Ridge morphology.
Residual Ridge Morphology: Maxilla Only
Residual ridge morphology is the most objective criterion for the maxilla, because measurement
of the maxillary residual bone height by radiography is not reliable.
Type A (most favorable)
 Anterior labial and posterior buccal vestibular depth that resists vertical and horizontal
movement of the denture base.
 Palatal morphology resists vertical and horizontal movement of the denture base.
 Sufficient tuberosity definition to resist vertical and horizontal movement of the denture
base.
 Hamular notch is well defined to establish the posterior extension of the denture base.
 Absence of tori or exostoses.

Type B
 Loss of posterior buccal vestibule.
 Palatal vault morphology resists vertical and horizontal movement ofthe denture base.
 Tuberosity and hamular notch are poorly defined, compromising delineation of the
posterior extension of the denture base.
 Maxillary palatal tori and/or lateral exostoses are rounded and do not affect the posterior
extension of the denture base.
Type C
 Loss of anterior labial vestibule.
 Palatal vault morphology offers minimal resistance to vertical and horizontal movement
of the denture base.
 Maxillary palatal tori and/or lateral exostoses with bony undercuts that do not affect the
posterior extension of the denture base.
 Hyperplasic, mobile anterior ridge offers minimum support and stability).-of the denture
base.
 Reduction of the post malar space by the coronoid process during mandibular opening
and/or excursive movements.
Type D
 Loss of anterior labial and posterior buccal vestibules.
 Palatal vault morphology does not resist vertical or horizontal movement of the denture
base.
 Maxillary palatal tori and/or lateral exostoses (rounded or undercut) that intcrfere with
the posterior border of the denture.
 Hyperplasic, redundant anterior ridge.
 Prominent anterior nasal spine.

Muscle Attachments: Mandible only
The effects of muscle attachment and location are most important to the function of a mandibular
denture .these characteristics are difficult to quantify.
Type A (most favorable)
 Attached mucosal base without undue muscular impingement during normal
function in all regions.
Type B
 Attached mucosal base in all regions exccpt labial vestibule
 Mentalis muscle attachment near crest of alveolar ridge.
Type C
 Attached mucosal base in all regions except antcrior buccal and lingual vestibules
(canine to canine).
 Genioglossus and mentalis muscle attachments near crest of alveolar ridge.
Type D
 Attached mucosal basc only in the posterior lingual region.
 Mucosal base in all other regions is detached.
Type E No attached mucosa in any region.
Maxillomandibular Relationship
It characterizes the position of the artificial teeth in relation to the residual ridge and/or to
opposing dentition. Examine the patient and assign a class as follows:
 Class I (most favorable): Maxillomandibular relation allows tooth position that
has normal articulation with the teeth supported by the residual ridge.
 Class II: Maxillomandibular relation requires tooth position outside the normal
ridge relation to attain esthetics, phonetics, and articulation (eg, anterior or
posterior tooth position is not supported by the residual ridge; anterior vertical
and/or horizontal overlap exceeds the principles of fully balanced articulation).
 Class III: Maxillomandibular relation requires tooth position outside the normal
ridge relation to attain esthetics, phonetics, and articulation (ie crossbitc-anterior
or posterior tooth position is not supported by the residual ridge).

Factors Influencing the Outcome of Prosthetic Treatment
The successful outcome of prosthetic treatment depends upon
(1) The dentist – who makes a diagnosis, prepares a treatment plan and undertakes the
clinical work.
(2) The dental technician – who constructs the various items which culminate in the
finished dentures.
(3) The patient – who is faced with coming to terms with the loss of all the natural teeth
and then of having to adapt to the dentures and accept their limitations.
The patient’s contribution
The patient must:
• Be able to come to terms with the loss of the natural teeth and their artificial
replacement
• Become accustomed to the sensation of the dentures, a process known as habituation
• Learn to control the dentures
• Accept and hopefully appreciate the new appearance.
Psychological effects of tooth loss
 In an investigation of patients receiving prosthetic treatment, most having lost their
remaining natural teeth several years previously and seeking replacement dentures, 45%
admitted to having found it difficult to accept the loss (Davis et al. 2000).
 Many of those who had difficulties took longer than a year to get over the loss, and more
than a third had still not accepted it by that time.
 They expressed feelings of sadness, anger and depression and many felt that these last
extractions had made them feel prematurely old and lost a part of themselves.
 There was loss of confidence, a restriction in choice of food and a lowered enjoyment of
that food. Relationships with others were affected and many patients avoided looking at
themselves without their dentures in place.

Habituation
 Habituation has been defined as: ‘A gradual diminution of responses to continued or
repeated stimuli’.
 When new dentures are placed in the mouth, they stimulate mechanoreceptors in the oral
mucosa. Impulses arising from these receptors, which record touch and pressure, are
transmitted to the sensory cortex with the result that the patient can ‘feel’ the dentures.
 For the first-time denture wearer this bombardment of the sensory nervous system almost
inevitably results in pronounced salivation which, fortunately, only lasts for a few hours.
The continuing stimulation of these receptors does not result in a corresponding
continuous stream of impulses. The receptors adapt to this stimulation and as a
consequence the patient begins to lose conscious awareness of the new shapes in the
mouth.
Control of the dentures
 The patient’s ability to control dentures involves a learning process that, initially, is a
conscious endeavour.
 The learning process has come to the rescue. As a result of repetition, new reflex arcs
have been set up in the central nervous system and the conscious effort has been replaced
by a subconscious behaviour pattern.
The patient’s perception of appearance
 Because a pleasing appearance is a subjective evaluation, there is obviously room for the
dentist and patient to have differing opinions. However, open disagreement does not
predispose to successful treatment and so it is vitally important that the dentist should
take careful notice of a patient’s views on appearance.

Factors predicting treatment outcome
• Age of the patient:
- In general, as patients grow older, it takes longer for them to adapt
successfully to new dentures
• Quality of care provided and previous complete denture experience
- In cases where examination of the mouth indicates that the prognosis for
dentures is poor, it is essential for the dentist to warn the patient in advance of
the difficulties and to describe the steps that will be taken to minimize them.
• The patient’s expectations and attitude towards dentures
- a patient’s attitude to dentures can be a useful predictor of satisfaction or
dissatisfaction.
• Opinion of a third party
- Negative comments from friends and relationscan cause disappointment
and rejection of the prostheses, while positive comments can promote
cheerful acceptance of the treatment.
• General health.
- Significant impairment of general bodily or mental health may affect the
learning process adversely, with the result that the patient becomes
discouraged because of major difficulties in mastering new dentures.

Transition from the Natural to the Artificial Dentition
Methods of transition
The various methods of making the transition from natural to artificial dentition may be
considered under the following headings.
 Transitional partial dentures
Transitional partial dentures restore existing edentulous areas. They may be worn for a
short period of time before the remaining natural teeth are extracted and the dentures are
converted accordingly.
 Overdentures
Overdentures are fitted over retained roots and derive some of their support from that
coverage. Special attachments may be fi xed to the root faces to provide mechanical
retention for the denture. If, in due course, the roots have to be extracted, the overdenture
can be converted into a complete denture.
 Immediate dentures
Immediate dentures are constructed before the extraction of the natural teeth and are
inserted immediately after removal of those teeth.
 Clearance of remaining natural teeth before making dentures
This approach differs from all those mentioned previously in that, after the extractions,
time is allowed for initial healing and alveolar bone resorption to occur before providing
complete dentures.
It is common practice for a period of several months to be allowed for healing and initial
alveolar modelling. This delay before taking impressions will produce more stable
supporting areas for the dentures, although resorption will continue indefinitely but at a
slower rate.

Disadvantages:
• Loss of masticatory function and appearance during the healing period.
• The undesirable mental and physical effects on a patient.
• Tongue and cheeks may invade the future denture space, making adaptation to
subsequent dentures more difficult.
• Difficulty in assessing vertical and horizontal jaw relationships when
constructing new dentures.
• The difficulty in restoring appearance if all information on the natural dentition
has been lost.
Factors influencing the decision of remaining teeth extraction:
1. The condition of the teeth and supporting tissues
Useful teeth can be retained if:
• It is feasible to undertake appropriate treatment to eliminate any disease present
• If there is confidence in the patient’s ability to maintain good oral health.
The presence of gross caries or advanced periodontal disease, coupled with no patient response
to oral hygiene instruction, makes the decision of whether or not to extract the teeth a simple one
2. The position of the teeth
a)Natural teeth opposing an edentulous ridge
The natural teeth generate high occlusal loads on of the denture, which may result in:
• Rapid destruction of the denture-bearing bone
• The production of a flabby ridge
• Complaints of a loose denture
• A deteriorating appearance as the denture sinks into the tissues
• Fracture of the denture base.

Only in extreme cases should the dentist consider trying to reduce the occlusal loads by
extracting sound teeth in the opposing arch.
b)Over-eruption of the teeth
 Extraction of over-erupted teeth may be required because they:
• Excessively reduce the vertical space available for the opposing prosthesis
• Have a poor appearance.
 endodontic therapy followed by decoronation of over-erupted teeth
3. Age and health of the patient
 It is true that early extractions may reduce problems of adaptation to dentures, but this
advantage must be balanced against the immediate probability of reduced oral function
and comfort in a patient who may be happy with a few remaining natural teeth and,
perhaps, a partial denture.
 One view that is regularly propounded is that every effort should be made to retain
useful, strategic teeth which may either help to stabilize a partial denture or which may
be converted into overdenture abutments.
4. The patient’s wishes
The following two scenarios occur occasionally and might cause the dentist some difficulty:
(1) Hopeless teeth that the patient wants to retain.
The dentist should carefully explain to the patient about the condition of the teeth and the
possible harmful consequences of retaining them.
(2) Sound, useful teeth that the patient wants extracted.
The dentist explains to the patient the nature of the clinical situation and to emphasise the
harm that unnecessary extraction of the remaining teeth would cause. If the patient still
need tooth extraction , the appropriate action by the dentist is most likely to withdraw
from the case, as to extract the teeth without clinical justification would be unethical.

COMPLETE DENTURE THEORY AND PRACTICE Anatomy and Physiology 2
Anatomy and Physiology In Relation to
Complete Denture Construction
Effect of tooth loss
Anatomy
 Anatomical Landmarks of Prosthetic Interest
 Musculuture
 Oral Mucosa
 Salivary glands
Physiology
 Physiology of bone
 Physiology of muscles
 Physiology of mucous membrane
Histology

Tooth Extraction
Extraction of teeth may be indicated upon several lines of thought including:
Extensive caries,
Development problems i.e. hypoplastic enamel,
Periodontally compromised teeth with severe mobility and/or furcation involvement.
Such teeth have poor prognosis and the clinician may convey this unto the patient and offer
possible treatment alternatives that may include extraction.
Prior to delving into the concept of immediate dentures, one must understand what tooth
extraction entails. The dentist must understand possible sequelae, time taken for bone healing
and possible consequences. Below describes the pathological processes that take upon an
immediate precedent once extraction occurs.
Extraction of teeth emulates processes similar to fracture healing. The
large cavitation formed where the tooth used to be required a large amount
of epithelial migration, collagen deposition, contraction and remodeling
during healing; thus, due to the nature of the cavitation bone healing at the
socket undergoes secondary intention.
Immediately following injury, bleeding occurs from torn vessels with subsequent formation
of a haematoma with presenting accumulating granular leukocytes. Tissue damage signals an
acute inflammatory response insinuating five cardinal. Connective tissue changes that
accompany the inflammatory response cause a loosening of the periosteal attachment to the
bone; the haematoma attains a fusiform shape.
Two to three days later, macrophages invade the clot to remove fibrin, red cells,
inflammatory exudates and debris. Bone fragments undergo necrosis and are attacked by the
infiltrating macrophages. Post-demolition, ingrowth of capillary loops and mesenchymals
cells occurs; these cells have osteogenic potential contributing to the haematoma. Migration
of epithelium occurs at the bony crest and eventually migrates until it becomes level with the
adjacent gingiva.
Following one week post-extraction, young fibrous tissue has penetrated most of the
socket; the proliferating epithelium may be tenous with possible complete coverage. There
may be initial signs of osteogenesis on parts of the socket wall and trabecular bone.
After two to three weeks, the invading cellular infiltrate has reduced but continued
vascularity with development of new fibrous tissue and woven bone. Furthermore,

osteoclastic activity occurs on the alveolar crests, labial plate and young bone in the base of
the socket; connective tissue beneath the surface epithelial layers matures.
After several months, the woven bone still undergoes remodeling while the overlying oral
mucosa has fully developed; the alveolar crests are being reabsorbed via osteoclasts.
Complete replacement by lamellar bone occurs after two to three years.
Effect of tooth loss
When natural teeth are present the occlusal forces are absorbed by the hydrodynamic
effect of the periodontal ligament. This complete mechanism is related to the maintenance of
integrity of the alveolar process. But the loss of teeth deprives these processes of the stimulus.
Under dentures all forces are transmitted to surface of the alveolar process as pressure.
Control of excessive pressure is an important consideration in CD construction.
After loss of Teeth
 Alveolar bone resorbed
 The orbicularis oris muscle loses its support
 The amount of vermillion border shown on the
upper lip is reduced
 The philtrum becomes flattened.
 The Nasolabial Sulcus becomes more prominent
with aging due to loss of teeth and loss of vertical
dimension.
 The mandible become closure to the nose .
 Lack of support of the facial muscles
 The shape and size of the alveolar ridges change when the natural teeth are
removed. The alveoli become mere holes in the jawbone and begin to fill up with
new bone, but at the same time the bone around the margins of the tooth sockets
begin to shrink away. This shrinkage, or resorption, is rapid at first, but it
continues at a resorbed rate throughout life.
 The maxilla resorbs upward and inward while the mandible resorb downward and
out word so many patient appear pragmatic.

Maxilla
 The shape and size of the alveolar ridges change when natural teeth are removed.
 The alveoli become mere holes in the jawbone and begin to fill up with new bone, but at
the same time the bone around the margins of the tooth sockets begins to shrink away.
 This shrinkage or resorption is rapid at first, but continues at a reduced rate throughout
life.
 The resorption of the alveolar process causes the foundation of the maxillary denture to
become smaller and otherwise change shape. If the denture is made soon after teeth are
removed, the apparent foundation may be large, but it also may be tender to pressure.
This is the result of in complete healing and a lack of cortical bone over the crest of the
residual alveolar ridge.
 If teeth have been out for many years, the residual ridge may become quite small and the
crest of the ridge may lack smooth cortical bony surface under the mucosa.
 There may be large nutrient canals and sharp bony spicules. These conditions limit the
amount of pressure that can be applied on the denture without creating pain.
Mandible:
 When teeth are removed the bony foundation offer mandibular denture becomes shorter
vertically and narrower buccolingually.
 The bony crest of residual ridge becomes narrower and sharper. Often sharp bony
spicules remain and cause tenderness when pressure is applied by denture.
 The total width of bony foundation becomes greater in the molar region as resorption
continues; the reason being the width of inferior border of mandible from side to side is
greater than width of alveolar process from side to side.
 Shrinkage of alveolar process in anterior region moves RR lingually first. Then as
resorption continues the foundation moves progressively further forward. Bone loss
continues on the mandible below level of alveolar process.
 With resorption of alveolar process occlusal contours of RR often develop that make
them curved from a low level anteriorly to a high level posteriorly causing severe
problems in denture stability.
 The total area of support from the mandible is significantly less than from maxillae. The
available denture bearing area for edentulous mandible is 14cm2 whereas for edentulous
maxillae its 24cm2. This means that mandible is less capable of resisting occlusal forces

than the maxilla are and extra care must be taken if available support is to be used to
advantage.
 The rate of resorption in the mandible is much higher (4X) than in the maxilla
The Dentition Function Curve
0
20
40
60
80
100
120
5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Age
Function(%age)
Dentate Partially dentate Edentulous
A model
for
understanding
dental
function
over time
The Dentition Function Curve
Ideal maxillary ridge:
• Abundant keratinized attached tissue
• Square arch
• Palate U-shaped in cross-section
• Moderate palatal vault
• Absence of undercuts
• High frenum attachments
• Well-defined hamular notches
Ideal mandibular ridge:
• Well defined retromolar pad
• Blunt mylohyoid ridge
• Deep retromylohyoid space
• Low frenum attachments
• Absence of undercuts
• Abundant attached keratinized
mucosa
• Adequate alveolar height

A classification of jaw form following tooth loss
Zarb classified the edentulous anterior jawbone into shape (quantity) and quality.
Quantity, Shape (types A though E) reflects a range of resorptive patterns relative to the
demarcation of the alveolar and basal jawbone.
A: most of the alveolar ridge is present.
B: Moderate alveolar ridge resorption has occurred.
C: Only basal bone remains.
D: Some resorption of the basal bone has taken place
E: Extreme resorption of the basal bone has taken place
Quality (types 1 through 4) reflects a range of cortical and cancellous patterns:
1. Almost the entire jaw is comprised of homogenous compact bone.
2. A thick layer of compact bone surrounds a core of dens trabecular bone.
3. A thin layer of cortical bone surrounds a core of dense trabecular bone.
4. A thin layer of cortical bone surrounds a core of low density trabecular bone.
Both parameters have been employed frequently in planning oral implant treatment.

Alveolar Ridge preservation
Residual ridge is the portion of the residual bone and its soft tissue covering that remains
after the removal of teeth
 One of the most important objectives of prosthodontic restoration is the
preservation of the supporting structures rather than the restoration of the missing
parts.
 The success or failure of a removable complete denture is dependent on many
factors, which include the condition of the alveolar ridge ,health of oral mucosa and
amount of the masticatory force of the opposing dental arch.
Causes of Alveolar Ridge resorption see flat ridge

Alveolar ridge maintenance
1) Periodontal diseases prevention
2) Conservation of remaining teeth. Retention of residual tooth roots in key locations
3) Root submergence
4) A traumatic extraction
5) Alveolar ridge maintenance (ARM) deals with the placement of osteo promotive
materials at extraction sites in an attempt to maintain the physiologic and anatomic
integrity
6) The impression should allow the fabrication of denture base that will provide the best
distribution of physical forces by accurate impression
7) Role of vertical dimension
- High vertical dimension will increase stress on residual ridge leading to ridge
resorption
- Jaw relation technique
- Occlusal plane
8) The occlusal table play an important role in ridge preservation
9) Role of occlusal surface morphology
- anatomical teeth cause more stresses on the ridge
- Semi anatomical teeth cause less stresses on the ridge
- flat teeth cause the least stresses on the ridge
10) Role of selected teeth material
- Acrylic teeth less stresses
- porcelain teeth more stresses
11) Premature contacts need to clinical remounting to decrease stress on the alveolar ridge
12) Balanced occlusion - Different Occlusal schemes
13) Denture base material and Well adapted and properly extended dentures base
14) over denture to slow down or prevent the resorption of residual ridge
15) role of implant in ridge preservation
16) Alveolar Ridge Augmentation
17) alveolar ridge augmentation using autogenous bone grafts from the iliac crest
18) Vertical Ridge Augmentation Using Alveolar Distraction Osteogenesis

Anatomical Landmarks of Prosthetic Interest
These are anatomical guides that help in denture construction. These landmarks are either bony
landmarks or soft tissue landmarks.
a- BONY LANDMARKS :
 Some bony landmarks are difficult to palpate, while others are easily palpated and
identified.
 The bony landmarks have the advantage of their being fixed in place.
 The measurement produced by bony landmarks can be duplicated with more
accuracy than measurements between soft tissue landmarks .
b- SOFT TISSUE LANDMARKS
 Easily identified
 Have the disadvantage of changing their relation according to their mobility
[ I ] Extra-oral Landmarks Of Prosthetic Importance
Landmark Description Significance
1- Inter-pupillary line - Imaginary line running between the
two pupils of the eye when the pt. is
looking straight forward.
- Establishing the anterior Occlusal
plane of the artificial teeth of the
denture.
2- Ala-tragus line
(Camper's line)
- Imaginary line running from the
Inferior border of the ala of the nose
to the superior border of the tragus of
the ear.
- Establishing the posterior occlusal
plane of the artificial teeth of the
denture.
3- Canthus-tragus line - Imaginary line running from the
outer canthus of the eye to the
superior border of the tragus of the
ear.
- Locating the position of the
condyles.

4- Naso-labial sulcus - Depression that extends from the ala
of the nose in a downward and lateral
direction to the corner of the mouth.
The sulcus becomes more prominent
with aging and due to loss of teeth
and vertical dimension. It can be
modified by proper degree of jaw
separation and tooth positioning.
Plumpers (thick denture flanges)
improve the condition but it may
interfere with muscular activity.
5- Vermillion border - The transitional epithelium between
the mucous membrane of the lip and
the skin.
The amount of vermillion border
shown on the lips depends on
1-The bulk of the orbicularis oris
muscle.
2- The amount of the labial alveolar
bone.
3-The alignment of the anterior teeth.
After loss of teeth, the amount of
vermillion border shown on the
upper lip is reduced. The condition
can be corrected by thickening of the
labial flange of the denture and
proper positioning of the anterior
teeth.
6- Mento-labial sulcus - Depression runs horizontally
between the lower lip and chin.
Its curvature indicates the character
of the maxillo-mandibular
relationship and the degree of over-
closure.
 Class 1 normal ridge
relationship: The sulcus
shows a gentle curvature
with obtuse angle
 Angle class II (retruded
mandibular relation): The
sulcus forms an acute angle
 Angle class III (protruded
mandibular relationship):
sulcus forms an angle of
almost 180
7- Philtrum - It is a diamond shaped depression at
the center of the upper lip and base of
the nose.
After loss of teeth, the philtrum
becomes flattened. This condition
can be improved by construction of
proper denture with an appropriate
arch-form and tooth alignment .

8- Modiolus - The point of meeting of buccinator
and other facial muscles distal to the
angle of the mouth. The modiolus is
held in position by the arch-form of
the maxillary teeth.
With the loss of teeth the modiolus
drops. The appearance can be
improved by proper positioning of
the maxillary teeth.
Narrowing of the lower denture base
related to the modiolus is usually
necessary to avoid displacement
9- Angle of the mouth
(commissure of the lips)
- Point of meeting between the upper
and lower lip.
- (Angular Chilitis): Inflammation
and ulceration as a result of:
1- Prolonged edentulism.
2- ↓ vertical dimension of complete
denture.
3- Vitamin B deficiency.
10- The Angle of the
Mouth and the Outer
Canthus of the Eye
The distance from the outer canthus
of the eye to the angle of the mouth
was used by Wills to determine the
vertical dimension of the edentulous
patient at rest by making the distance
from the base of the nose to the
lower edge of mandible equal to it.
A, The Philtrum, naso-labial sulcus, commissure of the lips& mento-labial sulcus.
B, Modiolus and Orbicularis Oris muscle.

The muscles contributing to the modiolus (dotted circle)

[ II ] Intra-oral landmark of prosthetic importance
The denture base must extend as far as possible without interfering in the health or
function of the tissues. The amount of biting force an edentulous ridge will tolerate is directly
proportional to the amount of surface area covered
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. Consequently, if we hope to assist a patient
to achieve maximum biting force and preserve the supporting structure over a longer period of time, The
maximum amount of denture bearing area must be covered.
The denture foundation can be divided into:
 Denture bearing/stress bearing areas. (denture foundation area) it is the surfaces of the
oral structures available to support a denture. or the tissues (teeth and/or residual ridges)
that serve as the foundation for removable partial or complete dentures.
 Peripheral limiting or sealing areas
Anatomic Landmarks of the Denture Bearing Area (supporting structures):
In the Maxilla In the Mandible
1-The residual ridge and hard palate
2- The incisive papilla
3- The palatine rugae
4-Median palatine raphe
5- Maxillary tuberosity
6- Torus palatinus
7- Fovea palatinae
8- Incisive fossae
9- Canine eminence
10- Buttress of the zygomatic bone
11- Palatal gingival vestige
1- Residual alveolar ridge
2- Retromolar pad
- 3- Internal oblique ridge
(mylohyoid ridge).
- 4- External oblique ridge
- 5- Buccal shelf of bone
- 6- Mental foraman
- 7- Genial tubercles
- 8- Torus mandibularis

Anatomic Landmarks that Limit the Periphery of the Denture (limiting structures):
In Relation to Maxillary Denture In Relation to Mandibular Denture
1- Labial frenum
2- Labial vestibule
3- Buccal frenum
4- Buccal vestibule
5- Pterygo maxillary notch (Hammular
notch)
6- Vibrating line.
1- Labial frenum
2- Labial vestibule
3- Buccal frenum
4- Buccal vestibule
5-Masseter muscle influencing area
6-Retromolar pad and inferior border of the
ramus
7- Pterygomandibular raphe
8- Plato glossal arch
9- Lingual pouch
10-Mylohyoid muscle influencing area
11- Lingual frenum
ANATOMY OF MAXILLARY DENTURE FOUNDATION
The maxillary denture is supported by two maxillae and the palatine bones. The palatine
processes of the maxillae are joined together at the midline in the median suture
The two palatine processes of the maxillae and the palatine bone form the foundation of the hard
palate and provide considerable support for dentures.
There are two maxillae, each consisting of a central body and three processes.
(a) The frontal process of the maxillae is directed upwards. It articulates anteriorly with
the nasal bone, posteriorly with the lacrimal bone and superiorly with the frontal bone.
(b) Zygomatic process of maxilla is short but stout and articulates with the zygomatic
bone.
(c) The alveolar process of maxilla bears sockets for teeth. The alveolar process arises
from lower surface of the maxilla. It consists of two parallel plates of cortical bone
buccolingual or labiolingual, which unite behind the last molar tooth to form the alveolar
tubercle. When teeth are present the cortical plates are connected by inter alveolar or
interdental septa.

Zygomatic process or malar process which is located opposite first molar region is one of
the hard areas found in mouths that have been edentulous for a long time. Some dentures
requires relief over this area to aid in retention and prevent soreness of underlying tissues.
The crest of the residual alveolar ridge
 covered with a layer of fibrous connective tissues,
 Most favorable for supporting the denture because of its firmness and position.
 The residual ridge and most part of the hard palate are considered the major or primary
stress bearing areas in upper jaw.
 The resorption of residual ridge limits its ability to support unlike the palate which is
resistant to resorption, so the residual ridge may be considered as secondary supporting
area. (ZARB)
Factors that influence the form and size of supporting bone of basal seat include.
(1) Its original size and consistency.
(2) The patient’s general health and resistance.
(3) Forces developed by surrounding musculature.
(4) Severity and location of periodontal disease.
(5) Forces accruing from wearing of dental restorations.
(6) Surgery at the time of removal of teeth.
(7) The relative length of time the different parts of jaws have been edentulous.
Hard palate
 It is a partition between oral and nasal cavities.
 Its anterior two thirds are formed by palatine process of maxillae and its posterior
1/3 by horizontal plates of palatine bone.
 The center of the palate may be very hard because the layer of soft tissue covering
the bone in the region of median palatal suture is extremely thin.
 The soft tissue covering the hard palate varies considerably in consistency and
thickness in different locations even though the epithelium is keratinised
throughout. Antero laterally the submucosa of hard palate contains adipose tissue
and posterolaterally it contains glandular tissue. The tissues should be recorded in
a resting condition, because when they are displaced in the final impression, they

tend to return to normal form within completed denture base creating an unseating
force on denture base or causing soreness in patients mouth. Proper relief of final
impression trays aids in recording these tissue in an undistorted form. In addition
the secretions from the palatal glands can be an important factors in selection of
final impression material.
 The glandular region of either side of the mid line in the posterior part of the
hard palate should be covered by the denture so it can aid in retention, but it
should not provide significant support for the denture because of the relatively
higher resiliency at this site. The mucous glands in this region are relatively thick
and they cover the blood vessels and nerves coursing forward in the palate from
greater palatine foramen. These vessels and nerves anastomose with vessels and
nerves passing through the nasopalatine canal and into the region of basal seat of
incisive papilla.
Incisive papilla
 It covers the incisive foramen and is located on the line immediately behind and
between the central incisions.
 Its position varies with different patients. It is located on the centre of ridge after
resorption has occurred in mouths that have been edentulous for long time.
 The location of incisive papilla gives an indication as to the amount of resorption
of residual ridge and thus is an aid in determining vertical dimension and proper
position teeth.
Incisive foramen (Nasoplatine foramen)
 The Nasoplatine nerves and blood vessels in submucosa exit the palate at right angles to
the margins of this bony fossa or foramen. Therefore even though the foramen is covered
with protective pad of fibrous CT called incisive papilla, the denture base should be
relieved over this area. Failure to relieve the denture base will result in pressure on the
nerves and blood vessels with resultant decrease in blood supply to anterior part of palate
and nerve irritation with accompanying burning symptoms.
 The location of incisive foramen gives an indication as to the amount of resorption of the
Residual ridge. It comes nearer to crest of the ridge as resorption progresses. thus aid in
determining the vertical dimension and the proper position of maxillary anterior teeth.

Palatine rugae
 The rugae in the anterior part of the hard palate are irregularly shaped rolls of soft tissue.
 They should not be distorted in an impression technique since rebounding tissue tends to
unseat the dentures.
 This area contributes to stress bearing role as well as retention, though in secondary
capacity.
Median palatine suture (mid palatal suture)
 The two horizontal palatine processes of the maxillary bone fuse in the midline to form
the mid palatal suture.
 The submucosa in this region is extremely thin and non resilient little or no stress can be
placed in this region during find impression making or the completed denture lest the
denture tend to rock over the center of palate when vertical forces are applied to the teeth.
In addition this part of mouth is highly sensitive and excess pressure can create
excruciating pain.
 Proper relief in the impression tray or completed denture is essential for accommodating
this nature of tissue.
Posterior nasal spine, greater/lesser palatine nerves and vessels
 The posterior border of the horizontal plates of the palatine bones unites in midline to
form the sharp posterior nasal spine. The posterior margins of the hard palate serve as the
anterior attachment for aponeurosis of soft palate.
 On each side of the hard palate the greater palatine foramen is located medial to the
third molar at the junction of the maxilla and horizontal plate of palatine bone. A groove
extends anteriorly from the foramen and contains the anterior (greater) palatine nerve and
blood vessels. Because the nerve and blood vessels course though a groove, rarely must
the denture base over the area be relieved.
In some instance bony spines are located near the greater palatine foramen. If these bony
projection present problems, the denture base should be relieved over these areas, or the
spines should be surgically removed.

Tuberosity region
 The tuberosity region often hangs abnormally low because the maxillary posterior teeth
are retained after the mandibular molars have been lost and not replaced, the maxillary
teeth extrude bringing the process with them often the low lying tuberosity is complicated
by excess fibrous connective tissue.
 This excess soft tissue can prevent proper location of occlusal plane if not removed. In
addition rough and irregular bone can be irritated by denture base.
Palatine fovea
 They are ductal openings into which ducts of other palatal mucosal glands drain. They
serve no function. According to Lye the fovea palatine are located on average of 1.31mm
anterior to anterior vibrating line.
Sharp spiny process
 There are sharp spiny processes on the maxillary and palatine bone, usually they have no
problem with complete denture but with resorption they can irritate the soft tissue lies
between them and denture base.
ANATOMY OF PERIPHERAL OR SEALING AREAS
The functional anatomy of the mouth determines the extent of basal surface of a denture.
The denture base should include the maximum surface possible within the limits of health
and function of the tissues it covers and contacts.
Labial frenum
 The lip movement near the maxillary labial frenum is
vertical and thus the notch becomes long and narrow.
If the frenum is pulled too far laterally during border
molding, the notch will become too wide and the
peripheral seal will be lost.
In some cases depressions are recorded beside the labial frenum notch due to muscle
band consisting of the origins of the nasal septal depressor muscle and the orbicularis
oris. In these cases the denture must be adequately relieved as not to disturb the function
of these muscles.

Labial vestibule
In region of labial vestibule, three objectives of an impression should be fulfilled.
 The impression must supply sufficient support to the upper lip to restore the relaxed
contour (for appearance) of the lip. The thickness of labial flange must be developed
according to amount of bone that has been lost from labial side of ridge.
 Secondly the labial flange of impression must have sufficient height to reach the
reflecting mucous membrane of the labial vestibular space without distorting it.
 Thirdly there must be no interference of labial flange with action of lip in function.
Buccal frenum
 The muscle movements around the buccal frenum are both vertical
and horizontal thus a wider notch should be formed compared with
the labial frenum. It will become a V-shaped notch.
 Generally the frenum runs obliquely and posteriorly therefore its
anterior movement should be recorded by pursing the lips such as when whistling during
border molding.
Buccal vestibule
 The size of the buccal vestibule varies with the contraction of the buccinator, the
position of the mandible and the amount of bone lost from the maxilla.
 The thickness of the distal end of buccal flange of denture must be adjusted to
accommodate the ramus and coronoid process and the masseter as
they function. When mandible moves forwards or to the opposite
side the width of buccal vestibule is reduced. When masseter
contracts under heavy closing pressure it also reduces the size of
space available for distal end of buccal flange.
 If border molding in the buccal space is inadequate, the denture will lose its seal because
of the ingress of air under the denture base when the buccal vestibule is opened during
situations in which the patient laughs and opens the mouth widely.
 In the rare case when it is hard to determine the width of the vestibule and thus the width
of the denture border due to severe alveolar ridge resorption, the appropriate width of the
vestibule can be estimated by using the remnants of the lingual gingival margin as a
guide. [HAYAKAWA]

– The buccolingual breadth of the dentate alveolar ridge (the horizontal breadth of
the alveolar process from the lingual gingival margin to the maximal projection of
the buccal surface of the ridge) is remarkably constant for every tooth position. So
the remnants of the lingual gingival margin can be located in the edentulous
mouth, the cheek position can also deduced by using it as a landmark.
– For example , the average measurement of the buccolingual breadth BLB in the
dentate molar region is 10-12 mm, However, after extraction of the teeth, the
remnant move outward 3-4 mm from the position in the dentate mouth, so the
width of the vestibule should be estimated by deducting this value from the mean
buccolingual breadth of dentate patient. [See Palatal gingival vestige]
Pterygoid process
 It projects downwards from the greater wing and body of sphenoid behind the
third molar tooth. Inferiorly it divides into medial and lateral pterygoid plates,
which are fused anteriorly but separated posteriorly by the v-shaped pterygoid
fossa.
 The fused anterior borders of the two plates articulate medially with the plate of
palatine bone and are separated laterally from the posterior surface of the body of
maxilla by pterygomaxillary fissure.
 The medial pterygoid plate is directed backwards. It has medial and lateral
surfaces and a free posterior border. The upper end of this border divides to

enclose a triangular depression called scapoid fossa. Medial to this fossa there is a
small pterygoid tubercle, which projects into the foramen lacerum. It hides from
view the posterior opening of the pterygoid canal. The lower end of the posterior
border is prolonged downwards and laterally to form the pterygoid hamulus.
 The lateral pterygoid plate is directed backwards and laterally. It has medial and
lateral surfaces and a free posterior border. The lateral surface forms medial wall
of infra-temporal fossa. The medial surface gives origin to muscles. The posterior
border sometimes has a projection called pterygo spinous process, which projects
towards the spine of sphenoid.
Pterygo maxillary (hamular) notch
 The pterygoid hamulus is a thin, curved process at the terminal end of medial
pterygoid plate of sphenoid bone. The exact position of hamular process is located
2-4 mm posteromedial to distal limit of maxillary residual ridge
 Although the pterygoid hamulus does not help in support of dentures, the area
between the maxillary tuberosity of maxilla and the hamulus is critical to design
of maxillary denture. It is used as a boundary of the posterior border of maxillary
denture back of tuberosity.
 The posterior palatal seal must be placed through the centre of the deep part of
hamular notch since no muscle or ligament is present at a level to prevent the
placement of extra pressure. The submucosa of mucous membrane is thick and
made up of loose areolar tissue.
 Additional pressures also can be placed on this tissue at the centre of the notch to
complete the posterior palatal seal.
Posterior palatal seal
 It is divided into two separate but confluent areas based on anatomic boundaries.
The posterior palatal seal extends medially from one tuberosity to another.
Laterally the pterygo maxillary seal extends through the pterygo maxillary notch
continuing for 3-4mm antero laterally approximating the mucogingival junction.
 The pterygo maxillary seal occupies the entire width of pterygo maxillary notch,
which is defined as band o loose CT lying between the pterygoid hamulus of
sphenoid bone and distal portion of maxillary tuberosity.

The notch is covered by pterygo mandibular fold, which extends from posterior aspect of
tuberosity posterior-inferiorly to insert into retromolar pad. This fold of tissue can influence the
posterior border seal if the mouth is in a wide-open position during final impression procedure.
Vibrating lines
 The PPS lies between the anterior and posterior vibrating lines.
 It is 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
 It should be described as area not line
 The anterior vibrating line located at the junction of attached tissues overlying
the hard palate and movable tissues of the immediately adjacent soft palate. This
should not be confused with anatomic junction of hard and soft palate.
It can be located by patient performing Valsalva Maneuver or instructing patient
to say Ah in short vigorous bursts. This places the soft palate inferiorly at its
junction with hard palate.
Due to projection of posterior nasal spine the anterior vibrating line is not a
straight line between the hammular processes. The anterior vibrating line is
always on soft palatal tissues. As soft palate extends posteriorly the action of
palatal muscles become more exaggerated.
 The posterior vibrating line is an imaginary line at the junction of aponeurosis
of tensor veli palatini muscle and muscular portion of soft palate.
It represents the demarcation between that part of soft palate has limited or
shallow movement during function and the remainder of soft palate that is
markedly displaced during functional movements.
It can be visualized by instructing patient to say Ah in normal unexaggerated
fashion. The posterior vibrating line marks the most distal extension of denture
base. The vibrating line is located and marked using an indelible pencil or marker,
and the impression tray is trimmed to this line
The distal end of the denture : should extend at least to vibrating line and in some instances it
may extend 1 to 2 mm posterior to vibrating line .[ ZARB] Should cover the tuberosity and
extend to hamular notch.

Techniques used in locating the vibrating line.
1- The clinician will often visualize the position of this line by having the patient say
"Ahh" and noting that the soft palatal tissues will usually lift while the hard palatal tissues
remain immobile. When the patient says "ah" the oft palate rises up and returns to its original
position when the patient relaxed
2- The Valsalva maneuver in which the patient is asked attempt to blow air through their
nose while the nostrils are gently pinched closed. While gently holding the tongue down with
a mouth mirror, the clinician will often easily visualize the line because the soft palate will
drop dramatically at the vibrating line using this technique. Blowing out through the nose
while closing the nostril causes a downward expansion of the soft palate
3- Other features indicating the position of this line may include a rather sharp color
change between the hard and soft palatal tissues at the vibrating line
4- Presence of the fovea near the line. According to Lye the fovea palatine are located on
average of 1.31mm anterior to anterior vibrating line.
5- Lastly, and often the easiest to visualize, may be the rather significant angular change
between the rather flat hard palate and the moderately to severely sloping soft palate. This
junction indicates the vibrating line.
A = "clinical" junction of hard and soft palates.
B=ah-line ,
C=fovea palatinae ,
D: anatomical junction of hard and soft palates.
 The hard palate possesses a portion made up of a 4-5 mm thickness of submucosa which
contain muscle insertions a well as glandular tissue. Even though the hard palate is
supported by bone, it is affected by the Levator and tensor muscles of the velum palatini
and so it is considered to be movable.

 Clinically, from only inspection and palpation, it is difficult to
determine whether the palate is supported by bone or not. So, the term,
"clinical' hard and soft palates, should be advocated
In the posterior part of the submucosa of the palate, the palatine glands
extend anteriorly from the soft palate to the first molar region taking the
shape of a mountain on either side of the midline.
The thickness is 4-6 mm in the soft palate and 2-3 mm even in the anterior part on the
hard palate. Thus there is no need to be anxious regarding how far the posterior border can be
extended. If the border is placed only on these palatine glands which possess a cushioning
effect, this would be adequate for retention, even if it is placed slightly anteriorly. A little
more extension may not lead to much better retention. If it is overdone the situation will be
worse than that of under extension and will lead to a gag reflex and irritation of the movable
mucosa. Therefore it is recommended that the posterior border is determined by carefully
avoiding the portion moving around the vibrating line whilst saying "ah".
Some clinicians might extend the posterior border posteriorly so as to cover the foveae
palatinae by considering the anatomical junction of the two palates, but this concept is not re-
commended. [HAYAKAWA]
Classification of soft palate
Based on angle that soft palate makes with hard palate. The more acute the angle, the
more muscle activity that will be necessary to achieve velopharyngeal closure (closing
nasopharynx).
The more the soft palate is markedly displaced in function, the less that can be covered
by denture base.
The more resorbed the edentulous ridge, more difficult in determining the soft palatal
configuration.

A – Broad PPS
B - Medium width PPS
C – Narrow PPS
Class I
Horizontal.
Minimal muscular activity.
Allows wide PPS but not very deep.
Since more tissue surface is covered it yields more retentive denture base.
Class III
The most acute contour.
Marked elevation of the musculature to create velopharyngeal closure.
Usually seen in conjunction with high v-shaped palatal vault.
Small area for posterior seal.
Deeper than class I
Class II
Designates those palatal contours that lie some where between class I and class III.
ANATOMY OF MANDIBULAR DENTURE FOUNDATION
The mandible is the movable membrane of the stomatognathic system. The body of
mandible is horse-shoe shaped. The distal portion of each site continuous upwards and
backward into the mandibular ramus.
The ramus divides superiorly into the condylar process and coronoid process. The
condyle (head) is the articular surface of the condylar process.
The connection of condyle with ramus is the slightly constricted mandibular neck.
Superior to the neck, the condyle is bent anteriorly so that the articular surface faces upward and
forward.
The coronoid process is a triangular bony projection that varies in size and shape. The
convex anterior border of coronoid process continues in to anterior border of ramus.
When the mandible is protruded the anterior border of ramus extends towards the
alveolar tuberosity, which is medial to ramus. If the distobuccal flange of denture is too thick, it
will cause discomfort when mandible is protruded and may dislodge denture during lateral
excursions.

The total area of support from the mandible is significantly less than from maxillae. The
available denture bearing area for edentulous mandible is 14cm2 whereas for edentulous
maxillae its 24cm2. This means that mandible is less capable of resisting occlusal forces than the
maxilla are and extra care must be taken if available support is to be used to advantage.
Crest of residual ridge
 The underlying bone of crest of RR is cancellous made up of spongy trabeculae.
Therefore crest of lower RR may not be favourable as primary stress bearing area for
lower denture.
 Proper relief to be provided for crest of lower ridge during making final impression.
Retro molar region and pad
 The distal end of mandibular denture region is bounded by the
anterior border of ramus, thus including the retro molar pad
posteriorly, which defines the posterior limit.
 The retro molar which is triangular soft pad of tissue at distal end of
lower ridge must be covered by denture to perfect the seal.
 It contains some glandular tissue, some fibers of temporalis tendon, fibers of superior
pharyngeal constrictor enter it from lingual and pterygo mandibular raphe enters the pad
at its supero posterior inside corner. The action of these limits the denture during
impression procedures.
 The posterior half of the retromolar pad is filled with resilient glandular tissues. The
peripheral seal of the denture can be obtained when the denture border is placed on this
tissue. The distal end of the denture should be placed at a point 213 of the way up the
retromolar pad .
 As the ternporalis muscle fibers attach to the distal portion of the retromolar pad,
stimulation from this muscle prevents the pad from resorption. So, the retromolar pad is
also used as a landmark for orientation of the occlusal plane. Therefore the retromolar
pad must be included in the impression. [HAYAKAWA]
 Retromolar pappilea is small pear shape area just anterior to the retromolar bad it is
dense fibrois connective tissue. [HEARTWELL]

Mylohyoid ridge
 If the denture border is short of the mylohyoid ridge, it will dig into
the residual ridge and cause pain. The border is shortened to remove
this pain, but shortly after, the shortened border again impinges upon
the residual ridge. This repetition will make the denture into a cord-
like and has poorer retention and stability.
 Border molding of the mylohyoid ridge area should be performed to
cover the ridge 4-6 mm beyond it. At the insertion appointment the
impression surface of the denture on the mylohyoid ridge is relieved so
that pain during mastication will be diminished.
 In addition, when the lingual denture border is extended properly as
mentioned above, the lingual polished surface can be shaped into a
concave form(the concave shelf) which is important [or the retention and
stability of the denture]
 When making an impression of this region, some think that the movement
of the mylohyoid muscle would be recorded by moving the tip of longue toward the
opposite side, However, tongue movement is due to the action of the genioglosus muscle,
The mylohyoid muscle contracts during swallowing.
 The patient is instructed to slightly touch the corner of the mouth with
the tongue. A exaggerated tongue movements during impression making
will be the cause of under extended borders, excessive movements
should be avoided. If the tongue is protruded over the dental arch, the
lingual sulcus will become shallow and an extremely shortened border will be obtained.
During ordinary function like mastication the tongue is not protruded outside dental arch
 The impression should be made to cover 4-6' mm beyond the mylohyoid ridge. This is
the length of the denture border in the mylohyoid ridge area. [HAYAKAWA]
The outline of the denture base can be determined easily and automatically by using these
indexes. It is just necessary to connect the index lines, namely lines placed 1 mm beyond
the external oblique ridge, 23 of the way from the anterior border of the retromolar pad
and 4 to 6 mm below the mylohyoid ridge. [HAYAKAWA]

Lingual tuberosity
 It is an irregular bony prominence on distal end of mylohyoid line.
 When this area is excessively prominent or rough it may present an undesirable undercut
requiring surgical intervention.
External oblique ridge (line)
 It is a ridge of dense bone extending from just above the mental foreman in a superior
and distal direction to become continuous with anterior border of ramus.
 In most individuals the external oblique ridge is the anatomic guide for lateral
termination of buccal flange of mandibular denture.
Buccal shelf area
 The area between the buccal frenum and the anterior edge of the masseter muscle. The
buccal shelf may be very wide and is at right angles to vertical occlusal forces, providing
excellent resistance to such forces.
 Some buccinator fibers are located under the buccal flange because the mandibular
attachment of this muscle is close to crest of ridge in molar region. The inferior part of
buccinator is attached to buccal shelf of mandible and thus contraction of muscles does
lift the lower denture.
Mental foremen
 It is located on the lateral surface of body of mandible between the first and second
bicuspids about halfway between the lower border of mandible and the alveolar crest.
 If the loss of RR is extensive, the foramen occupies a more superior position and denture
base must be relieved over the foramen to keep the denture base from irritating the
mental neurovascular bundle failing which the pressure exerted will cause numbness of
lower lip.
Mental spines (Genial tubercles)
 They are situated on lingual aspect of mandibular body in midline slightly above the
body. These bony elevations are often divided into a superior and an inferior section and
sometimes into right and left prominences.

 When loss of RR is extensive these spines are more superior position than crest of
existing ridge, requiring surgically intervention.
 The denture flange covering the genial tubercles may be widely
eliminated in many dentures for fear that the tubercle would be
irritated by settling of the denture due to occlusal forces.
However, if the denture border ends on the hard tissues, no
peripheral seal will be possible. The denture border must be
extended over the genial tubercles (and proper relief is done) in favor of improving the
peripheral seal.
Lingual ledge
 On side of genial eminence, a sharp bony ridge or crest which projects horizontally
toward the tongue and then falls off abruptly maybe palpated. This is a frequent source of
annoyance to denture. The ledge is a crescent shaped prominence located bilaterally
between genial tubercle and anterior end of mylohyoid ridge, which maybe continuous. It
exists in normal mandible as a slightly curved elevation but becomes more and more
prominent as the resorptive process reduces mandibular ridge and body.
 In mouths containing moderately resorbed RR, the lingual ledge maybe palpated for
below the level of the floor of the mouth and is not involved in denture impressions
unless the impression tray is over - extended. Where slightly resorbed the high
mandibular ridges are present, the ledge is not palpable. The presence of soreness of
lesions in this region explains the denture border impinging on the thin overlying mucosa,
thus not covering the lingual ledge completely.
Labial frenum
 Usually a single narrow band but may consist of two or more band. The activity of this
area tends to be vertical so the labial notch in denture should be narrow.
 The mandibular labial frenum is usually shorter and often wider than maxillary labial
frenum.
Labial sulcus
 The part of denture extending from labial frenum to buccal frenum is labial flange or
labial sulcus in edentulous mouth.

 This flange is limited in extension because the fibers of orbicularis oris and incisive labi
inferioris are fairly close to ridge crest. Muscles fibres are mainly horizontal. Mentalis
muscle originates from mental tubercles and inserts into lower lip (orb oris). It is a
vertical muscle and may be very active in some patients.
 The orbicularis oris is the major muscle in this region. as its
muscle fiber run horizontally, care must be taken not to
overextend the impression border in cases with weak muscle
tension in this region.
 The mentalis muscle is one of the muscles constituting the lower
lip. Its muscle fibers are vertical and the origin attaches high on
the mandibular alveolar process therefore the labial vestibule becomes narrow when this
muscle contract .
 However, if the lip is pulled too much as a result of being over conscious about this
contraction during border molding, the vestibule will become too shallow because the
attachment of the muscle is higher than the base of the labial vestibule
 Excessive activity in this area results in short flange which may not provided seal for
finished dentures.
 In patient exhibiting strong muscle tension of these muscles
in this region, this causes the lower up to fall inward and the
impression border becomes thin and short. As a result, the
completed denture might have an insufficient peripheral seal.
In general, the instruction is given to bite the operator's
fingers which are placed between the tray and the maxillary ridge. A the masticatory
muscles become tense and the lower lip becomes loose as a reflex, the impression is then
made in this situation
 When ridge is fair to good the labial borders should be thin (1-2mm) since thicker border
will distort the lips. When ridge is flat a thicker border is needed for lip and checks
support and to provide better seal.
 In general a thicker border creates better seal than thin border. Wider borders tend to
create favourable inclined plane and reduce the potential of losing peripheral seal.

Thicker border should be used with discretion, since they may cause discomfort poor
esthetics or interference with normal muscle movements.
Buccal frenum
 It is usually in the area of first premolar. It may be a single band but often two or more
bands.
 The oral cavities in this are horizontal as well as vertical (i.e. movements such as
puckering, grinning etc) so wider clearance is usually needed.
 The contour of denture will be little narrower in this area due to activity of depressor
anguli oris muscle.
Buccal vestibule
 Extends from buccal frenum posteriorly to outside back corner of retromolar pad and
from crest of RAR to cheek.
 The buccinator in cheek extends from modiolus (ant) to pterygomandibular raphe (post).
Labial and buccal borders are not as critical for borders seal because they shape of the
lips and checks create a facial seal. That is why it is possible to have a denture with open or short
flange (often used for immediate dentures) and still have good retention.
Masseter region
 Pain may occur on the buccal side of the retromolar
pad region during mastication even though the de-
nture is properly designed. This is due to the
masseter muscle, a strong elevator, which is lateral
to the retromolar pad and covers the buccinator
muscle.
 When the masseter muscle contracts, its
enlargement presses the denture border with the cramped buccinator muscle. As the
denture occludes it cannot move during function of the elevators. When the distobuccal
border of the denture base is extended into the functioning area of the masseter muscle,
the mucosa will be pressed against the denture base leading to pain.

 to avoid such a situation, the movement of the masseter muscle is recorded in the
impression by creating its reactive contraction through pushing the tray during the border
molding procedure. The tension of the masseter muscle will make a concavity in the
distobuccal outline of the impression. Another way is to reduce the over lengthened
border through observing the redness or displacement of the denture after insertion of
the new denture made by connecting the index line.
 An active masseter muscle will create a concavity in the outline of distobuccal border.
 The distobuccal border of mandibular impression encounters
the action of masseter to a greater or lesser degree depending on
the shape of the mandible and the origin of muscle.
 If ramus of mandible has a perpendicular surface and origin of
muscle on zygomatic arch is medial ward; the muscle pulls
more directly across the distobuccal denture border, therefore it forces buccinator and
tissues inward, reducing the space in this region. If the opposite is true, greater retention
is allowed on distobuccal portion of mandibular impression.
 The relative size of masseter will influence its action on the buccinator; a masseter that is
of smaller diameter will have less influence (perhaps none) on the border.
Distal extension of mandibular impression
 The distal extent of mandibular impression is limited by the ramus of mandible, the
buccinator fibers that cross from the buccal to lingual as they attach to the pterygo
mandibular raphe and the superior constrictor and sharpness of lateral bony borders of
retro molar fossa (formed by continuation of external and internal oblique ridges
ascending the ramus).
 If the impression extends on to the ramus, the buccinator and the adjacent tissues will be
compressed between hard denture border and the sharp external oblique ridge, which will
not only cause soreness but also limit the function of buccinator, which is a part of the
kinetic chain of swallowing.
 The desirable distal extension is slightly lingual of these bony prominences and includes
 the pear-shaped retro molar pad which forms a splendid soft tissue seal.

Pterygomandibular raphe
 The pterygo mandibular raphe or ligament originates from the pterygoid hamulus of
medial pterygoid plate and attaches to distal end of pterygoid ridge.
 It is partly the origin of buccinator muscle laterally and the superior constrictor muscle
medially.
 It is quite prominent in some patients and may even require and notch like clearance in
maxilla denture. A simple wide-open digital and visual inspection will usually determine
whether clearance is required or not.
 If extreme opening is allowed in making the impression the pterygo mandibular ligament
make a notch distal to alveolar tubercle
Alveololingual sulcus
It is the space between the residual ridge and tongue. It extends posteriorly from lingual
frenum to retromylohyoid curtain. Part of it is available for the lingual flange of denture.
The alveololingual sulcus can be considered in 3 regions
1. The anterior region (Premylohyoid fossa)
 This extends from lingual frenum to where the mylohyoid ridge curves down below the
level of sulcus.
 This fossa results from the concavity of mandible joining the convexity of mylohyoid
ridge.
 Lingual border of impression in anterior region show make definite contact with mucous
membrane of mouth when tip of tongue touches upper incisors.
Anterior lingual flange area
The border of the impression in this area is mainly influenced by the lingual frenum and
the genioglossus muscle. The genioglossus muscle and the Lingual frenum which lie over the
muscle move actively and are easily traumatized therefore their movement and tension must
be recorded exactly during border molding. Thus the patient must be instructed to make
appropriate tongue movements in order to record the exact depth and width of the notch
made by the lingual frenum.

To provide adequate clearance in this area the patient is instructed to make some overactive
movement such a licking the Lower lip , by moving the tip of the tongue from side to side.
Inadequate clearance may result in pain or inflammation. Tongue movement is never
requested during, impression making. However this is the only area where functional
movement of the tongue is necessary.
Lingual frenum
 Fibrous band of tissue that overlies the centre of genioglossus muscle. It is usually a
narrow single band of tissue but may be broad and exist as two or more frenums.
 It is rather shallow, sensitive and resistant. It should be registered in function because at
rest the height of its attachment is deceptive. In function it comes quite close to crest of
ridge although at rest it is much lower.
 It originates at midline from under surface of tongue and often terminates at the
sublingual (salivary) caruncles. In other instances it crosses and bisects the sublingual
crescent space and attaches to lingual aspect of mandibular ridge. Often it fans out to find
a broad insertion in alveolar mucosa.
 This structure should be palpated for tension during tray adjustment procedure. Careful
clearance is needed in the denture because the lingual frenum is attached to tongue and
inadequate clearance may result in pain or displacement of denture.
 They may be attached or near the crest of ridge. The lingual frenum maybe very short or
tongue-tie the patient can hardly protrude the tongue. Accessory frenums may occur in
almost any area of vestibule.
 It is influenced by genioglossus muscle and some what by anterior portions of sublingual
glands. The action of these muscles may raise and protrude the tongue.
 Frenums are basically fibrous connective tissue. They do not contract or expand like
muscles but rather are ligaments. They are accessory limiting structures for tongue, lips,
and muscles of cheek.

2. The middle region
 The part of alveololingual sulcus extends from premylohyoid fossa to distal end of
mylohyoid ridge curving medially from the body of mandible.
 When mylohyoid muscle and tongue are relaxed, the muscle drapes back under
mylohyoid ridge.
 If the lingual flange slopes towards the tongue, the tongue can rest on top of flange and
aid in stability of lower denture on RR it also prevents displacing the denture during
tongue movements and swallowing thus maintaining the seal.
 The length and width of mylohyoid flange is determined by membranes attachment of
tongue to mylohyoid ridge and width of hyoglossus muscle and can only be determined
by skilful border molding and impression.
 The lingual borders in mylohyoid areas are formed by contact with mylohyoid muscles in
a functional but not extreme contracted or elevated position.
 As Blanchard pointed out these borders leave a space when mylohyoid muscles are at
rest. The average mylohyoid border is 4-6mm below mylohyoid ridge fair-good ridge-
width 2-3mm flat-ridge 4-5mm.
Sub mandibular fossa
 It is a concave area in mandible that is inferior and distal to mylohyoid ridge. It is a bony
landmark and has little significance in impression making except it is necessary to be
aware of configuration.
SUBLINGUAL GLAND AREA
 The relationship of sublingual gland to lingual border is
controversial and confusing.
 They are located above mylohyoid muscle. They vary in
size and sometimes appear immense, that they seem higher
than RR. The position of gland is elevated when mylohyoid
muscles are in function (during swallowing) and they
appear to eliminate the lingual vestibules unless quite firm, which is rare, the sublingual
glands can be virtually disregarded during impression making.

 Similar to impression making in the mylohyoid ridge area the patient is never instructed
to perform any movements of the tongue, but asked only to relax the tongue comfortably.
The mouth is nearly closed and the tongue lies on the floor of the mouth completely. This
is the impression position of the tongue.
 Tongue movements ate made by pressing the anterior portion
of the tongue with the forefinger. Such an amount of tongue
movement is recommended for those who want to make
tongue movement.
 Through border molding, the depth of the Lingual vestibule
is recorded in this situation and this will in turn be used as the length of the lingual flange
in the sublingual gland area, so that the lingual border seal can be established effectively.
 The lower denture will not be lifted up, even though the
sublingual gland is raised, as the upper and lower teeth are
in contact when swallowing.
 On the other hand, the sublingual gland serves as a cushion
due to its soft and resilient nature and therefore it will
neither lift the denture nor will it covering mucosa be traumatized by the denture.
 If the denture border is made short to relieve the raised
sublingual gland a space will occur between the denture
border and the mucosa when the mylohyoid muscle is at
rest and thus the peripheral seal will be lost.
3. The posterior region (Retromylohyoid fossa/space)
 The space distal to the mylohyoid muscle is referred to as the
retromylohyoid fossa. It lies at the distal end of the alveolingual sulcus and
extends from end of mylohyoid ridge to retromylohyoid curtain
 It is bounded medially by anterior tonsillar pillar. posteriory by
retromylohyoid curtain and superior constrictor, laterally by mandible .
Anteriorly by lingual tuberosity. inferiorly by mylohyoid muscle .
[HEARTWILL]

 It is bounded by the mylohyoid muscle anteriorly the retromolar pad laterally, the
superior constrictor muscle posterolaterally, the palatoglossus muscle posteromedially
and the tongue medially. [HAYAWAKA]
 At this time, the posterior limit of the lingual border is defined by the palatoglossus
muscle[A] and the Lingual slip of the superior constrictor muscle[B]. This is called the
retromylohyoid curtain
 The retromylohyoid curtain is formed posteriorly by superior pharyngeal constrictor. The
action of the muscle and the tongue determine the posterior extent of lingual flange.
In the retromylohyoid fossa the lingual flange not affected by mylohyoid muscle so the
flange can turn laterally toward the ramus to fill the fossa and complete the typical S form of
correctly shaped lingual flanges. ZARB
 Pouch shaped retromylohyoid space is lined completely with loosely attached mucosa.
There are no supporting structures here since the medial surface of mandibular body
slope obliquely outward from mylohyoid ridge to mandibular border forming
submandibular fossa.
 Distal to mylohyoid muscle the space dips toward and outward to permit formation of
retromylohyoid eminence of mandibular denture. However denture flange should not
completely fill this area. it is necessary that the lining mucosa maintain continuous
contact with basal surface of flange which should not inhibit the tongue movement. The
external surface of retromylohyoid eminence is in continuous contact with lateral and
ventral surface of tongue, which limits flange thickness in accordance
with size and functional movements.
 During border molding, the border in this area is pushed into the
retromylohyoid fossa by the strong intrinsic and extrinsic tongue
muscles, it will show the so-called S-curve as viewed from the impression surface
Lateral throat form/ Distolingual vestibule/ Retromylohyoid fossa
 This anatomical area is probably least understood and frequently mismanaged. It is
bounded by :
Anteriorly - by mylohyoid muscle Laterally - pear shaped pad
Postero-laterally - superior constrictor muscle
Postero-medially - palatoglossus muscle and Medially – tongue

 The so called s- curve of mandibular denture as viewed from lingual results from the
stronger intrinsic and extrinsic tongue muscles which usually place the retromylohyoid
borders more laterally towards retromylohyoid fossa, as they appose weaker superior
constrictor muscle.
 The posterior limit of mandibular denture is determined by palatoglossus muscle and
somewhat by weaker superior constrictor muscle. This area is called Retromylohyoid
curtain.
Classification of lateral throat form
Neil described that the denture could have three possible lengths, depending on tonicity, activity
and anatomic attachments of the adjacent structures.
Class III
minimum length and thickness
Border 2-3 mm below mylohyoid ridge or sometimes at the ridge
Thickness no more than approx- 2mm
Knife-edge border if border terminates at mylohyoid ridge
Class I
Wide and long and wide flange.
Thickness varies
The Retromylohyoid curtain area (most distal border )should be thinner
Class II
it is half as long and narrow as class I and twice as long as class III
Most edentulous mouths have class I and class II lateral throat from class III is rare.
Besides border seal, another important reason for extending the lingual flanges into lingual
vestibules as for possible within their anatomical and functional limits. These flanges present
favourable inclined planes to the tongue resulting in vectors of force that helps maintain the
mandibular denture in place.
Lingual flange affected
 Distal extent - glossopalatine arch formed by glossopalatine and lingual extension of
superior constrictor.
 Medially - influenced by mylohyoid muscle attached to mylohyoid ridge.

 The buccal surface of flange rests on soft tissue and not on mucous membrane in contact
with bone.
 The mucolingual fold (the line of flexure of mucous membrane as it passes from tongue
to floor of mouth) is extremely flexible and mobile because of the type of tissue and due
to mobility of entire floor of mouth.
 The anterior part of lingual flange over sublingual gland is shallow because of mobility of
tissues that are controlled indirectly by mylohyoid muscle. The mylohyoid muscle in this
region extends nearly to inferior border of mandible and yet the glandular and other
tissues move above it. The combination of typical arch form of lingual side is projection
of mylohyoid ridge toward the tongue and existence of a retro mylohyoid fossa at distal
end of alveololingual sulcus causes the border of lingual flange to assume its typical s-
shape when viewed from impression surface.
 The mucous membrane lining the vestibular spaces and alveololingual sulcus is thin non-
keratinised epithelium. The submucosa is formed of loosely arranged CT fibres mixed
with elastic fibres. Thus the mucous membrane is freely movable. Anteriorly the
submucosa of mucous membrane lining the alveololingual sulcus contains components of
sublingual gland and is attached to genioglossus muscle. In molar region, the submucosa
attaches to mylohyoid muscles and the mucous membrane of retromylohyoid curtain is
attached by its submucosa to superior constrictor. Posterior to superior constrictor, which
runs in horizontal direction is medial pterygoid muscle running in vertical direction.
FLAT MANDIBULAR RIDGES
 On the labial surface of anterior region of the mandible several muscles are close to the
crest of ridge especially in badly resorbed ridges. This proximity accounts for the short
flanges necessary in this region. The muscles should not be impinged on since their
action is nearly at right angles to the flange. Many edentulous mandibles are extremely
flat because of loss of cortical bone.
 The surface is weakened and changes in form by the more rapid resorption of cancellous
portion of mandible. The denture-bearing surface often becomes concave, allowing the
attaching structures, especially on lingual side of ridge to fall over the ridge surface. Such
conditions require displacement of these tissues by the impression, which will gradually
establish a suitable bearing surface. The crest of greatly resorbed ridges is often at the

level of mental foramina and the nerves and blood vessels are easily compressed unless
the area is palpated and relieved on impression.
Insufficient space b/w maxillary tuberosity and mandible
 The maxillary sinus enlarges throughout life, if it is not restricted naturally by presence of
teeth or dentures.
 The angle of mandible becomes more obtuse by early loss of posterior teeth with
retention of anterior teeth. This destroys the necessary counterbalance against muscle pull
at angle of mandible. Such straightening of mandible reduces the maxilla mandibular
space in posterior region and creating lack of space for teeth and denture bas causing
denture failures.

ANATOMIC LANDMARKS OF THE MAXILLA
A] The Denture Bearing Area (Supporting Structures)
1- Residual ridge - The portion of the alveolar
process it's soft tissue
covering that remains after
extraction.
- It covers by a dense connective
tissue fibers so, it can be act as a
1ry
stress bearing area.
vault of the palate The vault of the palate has
different forms according to the
pattern of development of the
maxillary processes. The palatal
arch may be V-shaped, U-
shaped or flat.
The moderately high U-shaped
vault is the more common and is
more desirable for denture
stability.
2- Incisive papilla - Pear-shaped elevation present
in the midline behind the 2
centrals.
- After extraction of teeth it
migrates to the crest of the ridge.
- It should be relieved to avoid the
burning sensation of the palate.
3- Palatine rugae area - It is irregular elevations
radiates from the midline of the
anterior part of the palate.
- 2ry
stress bearing area.
- Prevent forward movement of
the denture.
- If it is sensitive or prominent it
should be relived.
4- Median palatine raphe - The mucoperiostium that
covers the median palatine
suture.
- When it is prominent it should
be relieved.
- Lack of relief cause:
1- rocking of the denture due to
bone resorption.
2- Tissue ulceration.
3- Mid-line denture fracture.
5- Maxillary tuberosity - Bony prominence located
posterior to the upper 3rd
molar.
- Aid in support, retention and
stability of the complete denture.
- When it is large:
1- Relieved.
2- Modify the path of insertion.
(unilateral enlargement).
3- Surgical removal.

6- Torus palatinus - Bony prominence present at
both sides of the midline of the
palate.
- present in 20% of the
population.
- It should be:
1- Relieved.
2- Surgical removal.
- Fovea palatinae
10-
- Two openings of minor
salivary glands present in both
sides of the midline posterior to
junction of hard and soft palate.
- It determines the posterior
extension of the upper complete
denture to be 2mm posterior to it.
8- Incisive fossa It is a slight depression in the
labial surface of the maxilla
opposite the region previously
occupied by the root of upper
lateral incisor.
9-Canine eminence It is found in the labial surface
of the maxilla. It is a rounded
bulge at the corner of the mouth
opposite the region previously
occupied by the root of the
maxillary canine.
10-Buttress (root) of the
zygomatic bone
It is formed by the lower portion
of the zygomatic process of the
maxilla which flares upward
and outward from the area
above the first molar
This area provides excellent
resistance to vertical forces as it’s
almost at right angles to the
occlusal forces.
- avoid vertical over-extension
in the first molar region, as
mucosal injury may result from a
sandwiching of the soft tissues
between the denture border and
the zygomatic process of the
maxilla.
With resorption the denture may
require relief over it
Palatal gingival vestige It is the remains of the palatal
gingivae. After tooth extraction
the position of the vestige
remains relatively constant, the
same as the incisive papilla
This can be a very helpful pointer
for posterior tooth positioning
during complete denture
construction. See buccal vestibule

B] Border structures that limit the periphery of maxillary denture
Maxillary labial frenum It is a fibrous band covered by
mucous membrane that extends
from the labial aspect of the residual
alveolar ridge to the lip. It may be
single or multiple and may be
narrow or broad.
It contains no muscle so it can be
surgically exiseced if it attach near
the crest of the ridge.
A labial notch must be
provided in the midline of the
denture border opposite to the
frenum. This notch prevents
ulceration of the frenum or
displacement of the denture.
A shallow bead can be formed
in the denture base around the
notch to help perfect the seal.
Labial vestibule The labial vestibule extends in both
sides between the labial frenum and
the buccal frenum.
The labial flange of the
maxillary denture occupies the
space bounded by the residual
alveolar ridge, and the lip.
The major muscle in this area
is orbicularis oris.
Buccal frenum It is a fold or folds of mucous
membrane extend from the buccal
mucous membrane reflection
towards the slope or crest of the
residual ridge. They vary in size,
number and position.
Associated muscles are:
Buccinator
Orbicularis oris
Levator anguli oris
It requires more clearance in
the denture flange for its
action. Inadequate provision
for the buccal frenum or
excess thickness of the flange
distal to the buccal notch can
cause dislodgment of the
denture.
Buccal vestibule It extends from the buccal frenum to
the hamular notch.
It houses the buccal flange of
the denture between the ridge
and the cheek.
the distal end of the buccal
flange of the demure must be
adjusted to accommodate the
coronoid process of the
mandible
Pterygomaxillary (hamular)
notch
It is a depression lies between the
pterygoid hamulous posteriorly and
the maxillary tuberosity anteriorly
It is a displaceable area about 2mm
wide
It is used as a boundary of the
posterior border of the
maxillary denture. The tissue
in this notch is easily
compressed and the post dam
line of the upper denture
should be carried into this
region to ensure an adequate
peripheral seal.
Bases short of the hamular
notch will end on the thin -
nonflexible – tissue of the
tuberosity and will
consequently lack retention.

Vibrating line of the palate The vibrating line is an imaginary
line drawn across the posterior part
of the palate that marks the
beginning of motion in the soft
palate when the patient says ah.
may also be identified by “Valsalva
maneuver ” by asking the patient to
close his nose using his fingers and
asking him to blow gently through
the nose .
It extends from one
pterygomaxillary notch to the other
notch on other side
A, Diagram of the upper arch.
B, Diagram of the lateral surface of the maxilla.

Complete denture theory and practice 2011.

Complete denture theory and practice 2011.

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Complete denture theory and practice 2011.