2. • In order to construct a prosthesis, a dentist requires an
understanding of the foundation, its components, its properties and
its qualities must be analysed to assure support for the proposed
prosthesis.
• Unless a dentist has a thorough knowledge of the anatomy and
physiology of the supporting structures, complete denture become
the product of a craftsman, who employs only knowledge of physics
and mechanics.
• A practitioner of health service to do classified as such, must know
and apply the basic sciences anatomy, physiology and psychology
as well as physics and mechanics.
• The purpose of this discussion is to introduce some aspects of
anatomy and physiology of the masticatory system that clearly have
relevance to complete denture Prosthodontics.
• It is convenient to regard the impression or fitting surface of the
dentures as comprising of two areas.
 A stress bearing or supporting area.
 Peripheral or sealing area
INTRODUCTION

4. TERMS THAT DESCRIBES BONE ANATOMY
PROCESS – general term for any prominence
FOSSA - depression on the surface of the bone
SUTURE – where two bones join
TUBEROSITY – bony prominence,
usually where muscle attaches, i.e. maxillary tuberosity
SUTURE FOSSA
MASTOID PROCESS

5. NOTCH – indentation on the edge of a bone
RIDGE – elongated prominence
FORAMEN - opening
Mental foramen
External oblique ridge
Mandibular notch

6. TWO TYPES OF BONE – COMPACT AND CANCELLOUS
CANCELLOUS BONE (also called spongy bone)
• makes up centre of bones
• Contains bone marrow spaces (called “trabeculation” on radiographs)
• More radiolucent than compact bone

7. COMPACT BONE-
• forms plates that form outside of bones, linings for alveolus, foramina,
etc…
• Is more radiopaque because of its density
Compact bone Cancellous bone

8. The anatomy of the maxilla has two main parts:
BODY(PYRAMIDAL SHAPE)
Anterior surface
Posterior surface
Orbital surface
Nasal surface
PROCESSES
Zygomatic
Frontal
Alveolar
Palatine

9. OTHER FEATURES
• FORAMINA
– infraorbital
– incisive fossa
– greater palatine
– lesser palatine
– posterior alveolar

10. ANTERIOR SURFACE OF MAXILLA
• It is directed forward and lateralward
• Just above those of the incisor teeth is a depression, the incisive fossa
• Lateral to the incisive fossa is another depression, the canine fossa; it is
larger and deeper than the incisive fossa, and is separated from it by a
vertical ridge, the canine eminence, corresponding to the socket of the
canine tooth
• Above the fossa is the infraorbital foramen, the end of the infraorbital
canal; it transmits the infraorbital vessels and nerve.
• Medially, the anterior surface is limited by a deep concavity, the nasal
notch which ends below in a pointed process, which with its fellow of
the opposite side forms the anterior nasal spine.

11. ORBITAL SURFACE

13. POSTERIOR SURFACE
• It is directed backwards and laterally
• It forms anterior wall of the infratemporal fossa
• Anterior and posterior surfaces are seperated by ridge which
leads to the socket of 1st molar tooth
• Near the centre of posterior surface 2 to 3 openings of dental
canal for posterior superior alveolar vessels and nerves
• At the lower end there is a raised maxillary tubrosity which is
rough in the upper part of its medial end for tubercle of the
palatine bone which has the attachment of superficial fibres of
themedial pterigoid muscles
• Above this smooth surface which forms the boundry of the
ptrigopalatine fossa is grooved for the maxillary nerve, this
groove is contineous with the infra orbital groove

14. NASAL SURFACE

15. MAXILLARY SINUS

17. PROCESSES

22. FORAMINA
– infraorbital
– incisive fossa
– greater palatine
– lesser palatine
– posterior alveolar

23. OSTEOLOGY OF MANDIBLE

24. • Largest and strongest bone of the face
• Curved horizontal body; convex forwards
• It has two rami which project upward from posterior end of
the body
• The body is horse shoe shaped
EXTERNAL SURFACE
• Faint ridge: symphisis menti
• Mental protuberance in the triangular area below sympisis
menti
• Mental tubercle on each side of mental protruberance
• Mental foramen between premolar teeth
• Oblique line

25. INTERNAL SURFACE

26. BORDERS

29. ORAL MUCOUS MEMBRANE
The oral mucous membrane, which covers the bone of the maxilla and
mandible, provides support for the complete dentures. The denture comes
in direct contact with the mucous membrane and thus, their features must
be analysed how best the support can be utilized.
The oral mucosa can be divided into three categories depending on
its location in the mouth and its function
They are
1.Masticatory mucosa - which covers the crest of residual ridge, including
residual attached gingiva, firmly adherent to supporting bone. & Secondly
the hard palate
The masticatory mucosa is characterised by well-keratinised layer on its
outermost surface that is subject to changes in thickness depending on
whether dentures are worn and on the clinical acceptability of dentures.
2.Lining mucosa - is generally found to cover the mucous membrane in the
oral cavity that is the firmly attached to periosteum of the bone. It forms the
covering of lips and cheeks, the vestibular spaces, the alveololingual sulcus,
the soft plate, the ventral surface of tongue, and the unattached gingiva
found on slopes of residual ridges. It is devoid of keratinised layer and is
freely movable with the tissues to which it is attached because of its elastic
nature of lamina propria.

30. 3.The specialized mucosa - covers the dorsal surface of tongue. The mucosal
covering is keratinised and includes specialized papillae on upper surface of tongue.
The nature of mucous membrane in different parts of mouth varies
between patients and within the some patient. The keratinised layer
of epithelium (stratum corneum) maybe totally absent in some
instances and extremely thick in others.
The thickness and consistency of submucosa are largely responsible
for support that the soft tissues afford the dentures since in most
instances the submucosa makes up the bulk of mucous membrane.
In a healthy mouth, the submucosa is firmly attached to periosteum
of the underlying bone of RR and will usually successfully withstand
the pressures of dentures. When submucosal layer is thin over the
bone, the soft tissue will be non resilient and small movements of
denture will tend to break retentive seal. When submucosal layer is
loosely attached to periosteum of RR or is inflamed or edematous the
tissues are easily displaceable and stability and support of dentures
are adversely affected.

34. MUCOUS MEMBRANE OVERLYING THE DENTURE BASE AREA
The foundation for dentures (DBA) is made up of
bone covered by mucous membrane i.e.
epithelium ,mucosa and sub mucosa. In the sub
mucosa are the vessels that carry blood to Basal
seat and the nerves that innervate it. The
denture bases rest on the mucous membrane,
which serves as a cushion between the bases
and the supporting bone.
Each type of tissue found in the oral cavity has
its own characteristic ability to resist external
forces. This is important to maintain the health
of the tissues of the basal seat and to the
stability and support of dentures.
The thickness of the soft tissue covering the
bone is different in different parts of the maxillary
basal seat. The nature and relative thickness of
the soft tissues in different parts of the basal
seat determine the amount of support these
tissues can provide for the denture.

35. STRESS BEARING AREAS
The residual ridge and most part of the hard palate are considered the major or
primary stress bearing areas in upper jaw.
The crest of the residual alveolar ridge is covered with a layer of fibrous
connective tissues, which is most favourable for supporting the denture because of its
firmness and position. The artificial teeth placed near the ridge so that leverage will be
minimal.
The configuration of bone of basal seat of maxillary denture varies in
configuration from each patient.
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.

36.  Microscopically the mucous membrane covering the crest of upper residual ridge in
healthy mouth is firmly attached to periosteum of bone of maxillae by connective
tissue of sub mucosa.
 The stratified squamous epithelium is thickly keratinised.
 The sub mucosa is devoid of fat or glandular cells and thus does not become
edentulous but characterised by dense collagenous fibers that are contiguous with
lamina propria.
 The submucosa though relatively thin in comparison to other parts of mouth is still
sufficiently thick to provide adequate resiliency for primary support of the denture.
 The mucous membrane covering the crest is comparable to attached gingiva in
edentulous mouth except submucosal layer in edentulous mouth is usually thicker
than is found in attached gingiva of dentulous mouth
 As mucous membrane extends from crest along the slope of the upper RR to
reflection, it tends to lose its firm attachment to underlying bone, marking the end of
residual attached mucous membrane. The loosely attached mucous membrane in
this region is non-keratinised or slightly keratinized
 Submucosa contains loose CT and elastic fibers. This type of tissue will not
withstand forces of mastication or other stress transmitted through denture base
and firmly attached over ridge crest. Less stress is placed on movable tissue of
slope of ridge during impression making because the impression material is closer
to escape ways (border of impression tray) than material over crest of ridge

37. HISTOLOGY OF RESIDUAL RIDGE CREST
Note: the thick submucosal layer above
compact bone making it the
primary stress bearing area

38. Histology of mucous membrane in
Anterolateral part of palate
Posterolateral part of palate
HISTOLOGY OF MAXILLARY TUBORISITY & HARD PALATE

39. HISTOLOGY OF MIDPALATINE SUTURE AREA
Note: thin submucosal layer
unsuitable for support
of the denture

40. HISTOLOGY OF PERIPHERAL OR SEALING AREAS
Histologically the mucous membrane lining the vestibular space depicts a relatively
thin non-keratinised epithelium. The submucosal layer is thick and contains large
amounts of loose areolar tissue and elastic fibres. The nature of submucosa in
vestibular space makes tissue easily movable. Thus the labial flanges and buccal
flanges of upper impression can easily be over extended or under extended.
The procedures for molding the borders of an impression to allow for
natural muscles activity of lips and checks are important in the development of
properly formed flanges that will be in harmony with the histologic limitation of these
tissues
Note :loose areolar tissue and
elastic fibers permit
relatively large movement
of tissues at the reflection.

41. SUMMARY AND CONCLUSION
Complete dentures are artificial substitute for living tissues teeth and
their supporting structures that have been loss. They must replace the form of
living tissues as nearly as possible and more important they must function in
harmony with the remaining tissues that both surround and support them.
In order to achieve a harmonious co existence between living oral
tissues and the non living substitutes dentures, the dentist must fully recognize
and understand the anatomy and physiology of tissues that support them and
influence the design of CD.
Thus it is up to the dentist to have a basic knowledge of functional
anatomy of the oral tissues which support the CD and utilize thus knowledge to
incorporate various impression techniques that would best record the tissues in
their normal and function state within the physiologic limits of tissues.
Their knowledge has direct clinical implications for dentists and
directly affects their success when they treat edentulous patients.

42. REFERENCES
1. Zarb A.G, Bolender L.G, Rickey C.J, Carlsson G.E “BOUCHER’S Prosthodontic treatmen
for edentulous patients X Edition, XI Edition , C.V Mosby company.
2. Winkler S . Essentials of Complete Denture Prosthodontics, II Edition.
3. Heartwell C M Jr, A O. Rahn Syllabus of Complete Dentures IV Edition.
4. B.D. Chaurasia Human Anatomy B.D. Chaurasia III Edition volume 3.
5. Anderson N.J , Stores R Immediate and Replacement Dentures III Edition.
6. Sharry J.J Complete Denture Prosthodontics N.Y III Edition.
7. A.A Grant Variable denture limiting structure of edentulous mouth
Maxillary border area- Part I JPD 1966; 16; 194
Mandibular border area Part JPD 1966; 16; 204
8. Levin B. Impressions for Complete dentures. Quintessence Pub. Co. Inc 1984.
9. Nairn R.I. Neil D.J. Complete denture prosthetics III Edition

43. 10)Ten Cate’ s Oral Histology – 6th ed
11)Orbans Oral Histology and Embryology –
10th ed