ANATOMICAL LANDMARKS RELATED TO COMPLETE DENTURES1.ppt

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1. ANATOMICAL LANDMARKS ANATOMICAL LANDMARKS
OF MAXILLA AND MANDIBLEOF MAXILLA AND MANDIBLE

2. Introduction Introduction

Complete dentures are artificial substitutes for Complete dentures are artificial substitutes for
living tissues that have been lost. living tissues that have been lost.

Function in harmony with the remaining tissues Function in harmony with the remaining tissues
that both support and surround them. that both support and surround them.

The dentist must fully understand both the The dentist must fully understand both the
macroscopic and microscopic anatomy of the macroscopic and microscopic anatomy of the
supporting and limiting structures of the dentures. supporting and limiting structures of the dentures.

3. 
Determines: -Determines: -

The selective placement of forces &The selective placement of forces &

The form of the denture borders that will be in The form of the denture borders that will be in
harmony.harmony.
The foundation for dentures is called the The foundation for dentures is called the basalbasal
seatseat, and it is made up of bone that is covered by, and it is made up of bone that is covered by
mucous membrane.mucous membrane.

4. Maxillary Edentulous Arch

5. 
Residual alveolar ridgeResidual alveolar ridge: the bony process that : the bony process that
remains after teeth have been lost and includes remains after teeth have been lost and includes
the mucous membranes that covers the bone. the mucous membranes that covers the bone.


The posterior residual ridge is considered to be The posterior residual ridge is considered to be
the primary stress bearing area in the upper jaw. the primary stress bearing area in the upper jaw.

It can carry maximum stress without discomfort It can carry maximum stress without discomfort
and least likely to resorb under pressure.and least likely to resorb under pressure.

6. 
The mucous membrane - firmly The mucous membrane - firmly
attached to the periosteum. attached to the periosteum.

Thickly keratinized Thickly keratinized

The thick sub-mucosal The thick sub-mucosal
layer provide adequate layer provide adequate
resiliency.resiliency.

The outer surface of the bone The outer surface of the bone
is compactis compact
Bone
Periosteum
Submucosa
Mucosa

7. 
Anterior alveolar ridge:Anterior alveolar ridge: secondary area of support secondary area of support
as the anterior ridge seems to be more susceptible to as the anterior ridge seems to be more susceptible to
resorption. resorption.

Slopes of the ridgesSlopes of the ridges: as the mucous membrane : as the mucous membrane
extend from the crest, it tends to lose its firm extend from the crest, it tends to lose its firm
attachment. attachment.

8. Rugae area
•Raised areas of dense
connective tissue
radiating from the midline in
the anterior one third of the
palate.
•The rugae are often compressed or distorted from an
ill-fitting denture and should be allow to return to their
normal form prior to impression making.

9. 
Rugae area is considered to be the secondary Rugae area is considered to be the secondary
stress bearing area, since it can resist the forward stress bearing area, since it can resist the forward
movement of the denture. movement of the denture.

They are irregularly shaped rolls of soft tissues They are irregularly shaped rolls of soft tissues
and serve no function.and serve no function.

The rugae area should be faithfully reproduced The rugae area should be faithfully reproduced
on the tissue side of the denture, but not on the tissue side of the denture, but not
necessarily on the palatal surface. necessarily on the palatal surface.

10. Incisive Papilla
•Large central papilla of the rugae.
•It is a pad of fibrous connective tissues overlying the
bony exit of the nasopalatine blood vessels and
nerves.
•It should not be displaced or compressed during
impression making.

11. Midline Palatine Suture
•The junctions of the palatine processes of the
maxillae.
•Often raised and covered with a thin layer of mucosa,
so some relief for this area may be necessary.
Mid palatal suture

12. •The soft tissues covering is non – resilient than the
tissues covering the residual ridges.
Compact bone
Submucosa
Mucosa

13. Fovea Palatini (Palatine fovea region)
These are two small indentations that are on
each side of the midline, usually on the distal
end of the hard palate.
Formed by a coalescence of several mucous
gland ducts.

14. Tuberosity area
•The maxillary tuberosities are the distal aspects of the
posterior ridges.
•The tuberosity region often hangs abnormally low

15. Torus palatinus
•It is the hard, bony areas
•Found in the centre of the palate.
•Classified into:
class I - absent or minimal
class II - moderate size
class III - large

16. Shape of the hard palate
•Cross section is either flat, rounded, ‘U’-shaped, or V-
shaped.
•A flat palate resists vertical displacement but is easily
displaced by lateral or torquing forces.
•The rounded and U-shaped palate has the best
resistance to vertical and lateral forces.

17. •The V-shaped palate is the most difficult because any
vertical or torquing movement tends to break the seal
•A patient with a V-shaped palate usually has class III
throat form, which flexes at the junction of the hard and
soft palate, making it difficult to place an adequate
posterior palatal seal.

18. Labial frenum
•It is a fold of mucous membrane, single, double,
triple cord, or a fan shaped.
•It contains no muscle and has no action of its own.
•It divides the maxillary labial vestibules into two
approx. equal but asymmetrical parts.

19. 
A pad of sub-mucosal soft tissue in the shape of a vertical A pad of sub-mucosal soft tissue in the shape of a vertical
column is observed on each side of the maxillary labial column is observed on each side of the maxillary labial
frenum. frenum.

These are attachments of the superior incisive muscles. These are attachments of the superior incisive muscles.

20. Labial frenum :
•The surface of the labial flange of the impression
tray should be relieved to allow for these
attachments.
•Should be wide enough and deep enough to
allow the frenum to pass.

21. Maxillary labial vestibule
•Extends between the right and left buccal frenums.
•Major muscle is the orbicularis oris, fibers are
horizontal, so careful border molding is necessary

22. Buccal frenum :
•Consist of one or more bands
•May be totally absent or may be in an entirely different
location.
•Creates a buccal notch, which is always wider than the
labial notch.

23. •The levator anguli oris (caninus) muscle attaches
beneath and affects its position.
•The orbicularis oris muscles pulls the frenum forward
•The buccinator muscle pulls it backward.
•The buccal frenum helps in the formation of the distal
slope of the maxillary labial denture border.

24. Buccal vestibule
•The buccal vestibule is opposite the tuberosity and
extends from the buccal frenum to the hamular or
pterygomaxillary notch.
•This space is between the ridge & the cheek and is
available for the buccal flange of the maxillary denture.

25. •It is influenced mainly by the modiolus and buccinator
muscles
•The buccinator fibres are horizontal and are relatively
flaccid in the area of origin, so it is easy to over extend
the impression.

26. 
The part of the denture base which fills this space is The part of the denture base which fills this space is
termed the termed the Retrozygomatic EminenceRetrozygomatic Eminence. .

The highest segment of this eminence is limited by The highest segment of this eminence is limited by
the lining mucosa which overlies the buccinator the lining mucosa which overlies the buccinator
muscles. muscles.

27. Hamular Notch (Pterygomaxillary notch)
•It is a displaceable area, about 2 mm wide
between the tuberosity of the maxilla and the
hamulus of the medial pterygoid plate.

28. Hamular Notch (Pterygomaxillary notch)
•This is accomplished by using a mouth mirror
or ‘T’ burnisher so that the edge drops into a
definite depression.

29. Posterior palatal seal area
•The soft tissues along the junction of the hard and soft
palates on which pressure within the physiologic limits
of the tissues can be applied by a denture to aid in the
retention of the denture.
•Divided into two separate but confluent areas; based
on anatomic boundaries.

30. Posterior palatal seal area
•Post palatal seal extends medially from one tuberosity
to the other.
•Pterygomaxillary seal, laterally extends through the
pterygomaxillary notch continuing for 3 – 4 mm
anterolaterally approximating the mucogingival
junction.

31. Anterior vibrating line
•It is an imaginary line located at the junction of the
attached tissues overlying the hard palate and the
movable tissues of the immediately adjacent soft
palate.
•Not the anatomic junction

32. Posterior Vibrating Line
•It is an imaginary line at the junction of the aponeurosis
of the tensor veli palatini muscle and the muscular
portion of the soft palate.
•It represents the line of demarcation

33. Mandibular Edentulous Arch

34. Crest of residual ridge
•The crest of the residual alveolar ridge is covered
by fibrous connective tissue
•The underlying bone is cancellous and without a
good cortical bony plate covering it.
•The fibrous connective tissue is favorable.
•The mandibular ridge is seldom favorable or ideal,
and it is frequently knife-edged, flabby or flat.
Inverted U Inverted U Inverted W Thin inverted V Undercut
parallel walls short with flat crest tall

35. Labial Border
•Labial frenum: contains a band of fibrous
connective tissue that helps to attach the orbicularis
oris.
•It is usually a single narrow band but may consist of
two or more bands.
•The activity of this area tends to be vertical, so the
labial notch in the denture should be narrow.

36. •Mandibular denture should be wide back of the
buccal frenum and narrow in the anterior labial
region.
•Frenum is usually shorter and often wider than the
maxillary labial frenum.
•Mandibular labial vestibule extends from right
buccal frenum to the left.

37. •There is presence of two soft elevations, one on
each side of the frenum.
•These pads mark the origin of the mentalis muscle,
the fibers of which insert into the skin overlying the
point of the chin and into the lower lip.

38. •The degree of nervous tension, present in an individual
can often be judged by the activity of the mentalis
muscle.
•It is the mentalis muscle, not the labial frenum, which is
capable of displacing a mandibular denture.

39. •Another major muscle is orbicularis oris. Its fibers are
mainly horizontal, so careful not to over extend the
impression in this area.

40. Buccal Frenum
•It may be single, two or more bands. The oral activities
in this area are horizontal as well as vertical i.e.
movements such as puckering, grinning etc, so wider
clearance is usually needed.
•The contour of the denture will be a little narrower in
this area due to the activity of the depressor anguli oris
muscle.

41. Buccal vestibule
•Extends for the buccal frenum posteriorly to the
retromolar pad and from the crest of the ridge to the
cheek.
•The buccal vestibule width and length are mainly
dependent on the buccal shelf and the buccinator
muscle.
•The buccal shelf has been identified as the surface of
the mandible that lies between the residual ridge crest
and the external oblique ridge.

42. •It is considered to be the primary stress bearing area of
the lower jaw.
•It is at right angle to the direction of vertical occlusal
force.
•It is covered by a layer of compact bone.
•Buccinator fibers are located under the buccal flange.
•The length of the buccal flange is not critical for
peripheral seal because the drape of the cheek
provides a facial seal.

43. External oblique ridge
•It represents the lateral limit of the mandibular body.
•It is a supporting rather than a limiting structure.
•The denture base must cover and extend beyond the
oblique ridge in order to end in the fatty and loose
connective tissue, which overlies the attachment of the
buccinator muscle.

44. •When the masseter muscle contracts, it alters the
shape and size of the distobuccal end.
•It pushes inward against the buccinator muscle and
pad of the cheek.
•An active masseter muscle with create a concavity in
the outline of the distobuccal border.
•Moderate activity will create a straight line.
•An inactive muscle will create convexity.

45. Lingual border anatomyLingual border anatomy
The lingual extension on mandibular impressions has The lingual extension on mandibular impressions has
been the most abused and misunderstood border region been the most abused and misunderstood border region
in complete dentures. in complete dentures.
An acceptable lingual border will result in a stable An acceptable lingual border will result in a stable
denture and can be secured with a proper understanding denture and can be secured with a proper understanding
of the anatomy and function of the floor of the mouth. of the anatomy and function of the floor of the mouth.

46. The lingual vestibule can be considered in three The lingual vestibule can be considered in three
regions. regions.

Anterior vestibule, the sublingual crescent area, Anterior vestibule, the sublingual crescent area,
premylohyoid. premylohyoid.

Middle vestibule, the alveololingual sulcus, Middle vestibule, the alveololingual sulcus,
mylohyoid area. mylohyoid area.

Distolingual vestibule, lateral throat form or Distolingual vestibule, lateral throat form or
retromylohyoid fossa. retromylohyoid fossa.

47. Anterior lingual vestibule (sublingual Anterior lingual vestibule (sublingual
crescent area or anterior sublingual fold or crescent area or anterior sublingual fold or
premylohyoid)premylohyoid)

Lingual crescent extension may be defined as the Lingual crescent extension may be defined as the
portion of the sublingual flange of the mandibular portion of the sublingual flange of the mandibular
denture that covers the anterior region of the floor of denture that covers the anterior region of the floor of
the mouth. the mouth.

It starts at the alveolar ridge crest and ends at the soft It starts at the alveolar ridge crest and ends at the soft
displacement tissue at the base of the tongue that is not displacement tissue at the base of the tongue that is not
directly supported by bone.directly supported by bone.

48. Lingual frenum
•It is either cordliker or fan-shaped and requires functional
freedom.
•It contains two sublingual caruncles of wharton’s duct
located on either side of the midline.

49. •The genioglossus muscles are attached to the genial
tubercles, which are small protuberances of bone near
the midline of the lower border of the mandible.
•Mandibular denture should be made to extend over the
genial tubercles in order to achieve better peripheral
seal.
Genial tubercle

50. 
When flange is develop in this manner, the border When flange is develop in this manner, the border
of the lingual flange has a typical ‘S’ shaped when of the lingual flange has a typical ‘S’ shaped when
viewed from the impression surface. viewed from the impression surface.

52. Thank youThank you