This document discusses anatomical landmarks that are important for making impressions for complete dentures. It describes landmarks in the maxilla like the hard palate, rugae, maxillary tuberosity, incisive papilla, and fovea palatine which provide support or need relief. Limiting structures like the labial and buccal frenums are also outlined. For the mandible, supporting areas include the buccal shelf and residual ridge while the mylohyoid ridge and mental foramen require relief. The principles of impression making and objectives of obtaining retention, stability and support are reviewed. Techniques for primary impressions using compound or alginate are demonstrated.

1. ANATOMICAL
LANDMARKS AND
PRIMARY IMPRESSION
DR ASWITHA G
1ST YEAR PG
DEPT OF PROSTHODONTICS
1

2. ANATOMICAL LANDMARK
• It is defined as a recognizable anatomic structure used as a point of reference
(GPT -9)
2

3. ANATOMIC LANDMARKS OF
MAXILLA
3
SUPPORTING STRUCTURES
• Hard palate – Rugae
• Residual alveolar ridge – maxillary
tuberosity
LIMITING STRUCTURES
• Labial frenum
• Labial vestibule
• Buccal frenum
• Buccal vestibule
• Hamular notch
• Fovea palatine
• Posterior palatal seal area
RELIEF AREAS
• Midpalatine suture
• Incisive papilla
• Torus palatinus
STRESS BEARING AREAS
• Primary – Horizontal slopes of hard
palate lateral to median sutures
• Secondary – Crest of residual
alveolar ridge, Rugae, Maxillary
tuberosity

4. LIMITING STRUCTURES
These are the structures which determine & confine the extent of
the denture
GPT-9
4

5. LABIAL
FRENUM
• Single band of fibrous connective tissue
• Consist of two or more fibrous bands
• No muscle attachment
5
Significance
• On activation creates the labial
notch in the denture base

6. LABIAL VESTIBULE
• Extends between the right and left buccal frenums
• Major muscle of the lip – Orbicularis oris
6
Significance
Fibers of Orbicularis oris run horizontally
Easy to overextend the impression
Careful border molding necessary

7. BUCCAL FRENUM
• Composed of one or more bands of fibrous connective tissue
• The frenum along with its associated muscles of expression creates the buccal notch
Muscles associated
• Buccinator
• Levator anguli oris
• Zygomaticus major
7
Significance
Due to frequent activity of the frenum and
its associated muscles the border molding
thickness of the buccal notch should be
fairly thin about 2mm

8. BUCCAL VESTIBULE
Extends from buccal frenum to hamular notch
This space is usually higher than any other part of the denture border
Structures influencing buccal vestibule
Buccinator
Masseter
Coronoid process
8

9. It is a displaceable area about 2mm wide
Situated between tuberosity of maxilla and hamulus of the pterygoid plate
HAMULAR NOTCH
Instrument used
Identified by means of T burnisher
9
Significance
 Determines the distal end of denture
 Ending the impression on the tuberosity will
result in a non retentive denture due to lack of
peripheral seal
 Overextending the impression distal to notch
will usually cause extreme discomfort due to
interference with ascending ramus of mandible

10. POSTERIOR PALATAL SEAL
AREA
It is defined as the soft tissue area at or beyond the junction of the hard
and soft palates on which pressure within the physiological limit can be
applied by a complete denture to aid in its retention
(GPT – 9)
10
Significance
Reduces the tendency for gag reflex
Aids in retention by maintaining constant contact with soft palate
 Compensates for polymerisation shrinkage
 Prevents food accumulation
 Reduces patient discomfort

11. M.M.HOUSE CLASSIFICATION
Describes the amount of posterior tissue that will accept the posterior palatal seal
Class I – more than 5mm of movable tissue available for post-damming; retention is usually good
Class II – 1-5mm of movable tissue available for post-damming good retention is usually possible
Class III – less than 1mm movable tissue available for post-damming; retention is usually poor
11

12. METHODS TO RECORD POSTERIOR PALATAL SEAL
• Conventional approach using ’T’ burnisher
• Fluid wax technique
• Arbitrary scrapping of the master cast
12

13. VIBRATING LINE
It is defined as an imaginary line across the posterior part of the palatal marking the divisions
between the movable and immovable tissues of the soft palate (GPT – 9)
Extends from one hamular notch to other
Passes 2mm in front of fovea palatina
13
Significance
Distal end of the denture should terminate 1 to 2 mm
posterior to the vibrating line

14. SUPPORTING
STRUCTURES
It is defined as the surfaces of oral structures that resists force, strains or pressures brought on them
during function
GPT – 9
14

15. HARD PALATE
The primary stress bearing area in the maxilla
Classification – In cross section
Flat
Rounded
U – shaped
V – shaped
15
• Flat palate - Resists vertical displacement but it is easily displaced
by lateral or torquing forces
• Rounded & U shaped palate - Has the best resistance to vertical
and lateral forces
• V shaped palate - Has got the least prognosis since any vertical or
torquing movements tends to break the seal easily

16. RESIDUAL ALVEOLAR
RIDGE
Crest of the residual alveolar ridge - important area of support
This bone is subjected to resorption which limits its
potential for support , unlike the palate which is resistant to
resorption
Considered as secondary stress bearing area
16
Factors influencing architecture of residual alveolar ridge
• Persons general health
• Forces developed by the surrounding musculature
• Severity of periodontal disease
• Forces acquiring from wearing of dental prosthesis
• Time length of edentulous span

17. RUGAE
Raised areas of dense connective tissue radiating from the
midline in the anterior one-third of the palate
17
Significance
Acts as secondary stress bearing area
Often compressed or distorted from an ill fitting
denture & should be allowed to return to their
normal form prior to impression making

18. MAXILLARY
TUBEROSITY
Most distal portion of the alveolar ridge
Significance
Important area of support as they are
least likely to resorb
Lateral reduction often required because
the coronoid process of the mandible is in
close contact during opening and lateral
jaw movements which may lead to an
inadequate space for a correctly extended
buccal flange
18

19. RELIEF AREAS
These areas resorb under constant load or contain fragile structures
Denture should be designed such that the masticatory load is not concentrated in these
areas
19

20. INCISIVE PAPILLA
A pad of fibrous connective tissue overlying the bony exit of the
nasopalatine blood vessels and nerves
20
Significance
• Should not be displaced or compressed while
impression making
• Pressure in this area can cause pain, parasthesia, burning
sensation
• Acts as a point of reference in the placement of canine in
denture fabrication

21. MID PALATINE SUTURE
It is the junction of the palatine process of maxilla which are often raised & covered with a thin
layer of mucosa
Most sensitive part of the palate
Hence relieving this area is
necessary
21

22. FOVEA PALATINA
• These are two small indentations fond on the distal end of the
hard palate
• Formed by coalesence of several mucous ducts
22
Significance
• Acts as a landmark for determining the posterior border
of denture
• Denture can extend 1-2mm beyond fovea

23. LABIAL FRENUM
• Usually a single narrow band but may consist two or more
bands
• Shorter and wider than maxillary labial frenum
23
Significance
The activity of this area tends to be vertical , so the labial
notch in the denture should be narrow

24. ANATOMIC LANDMARKS OF
MANDIBLE
24
SUPPORTING STRUCTURES
• Buccal shelf area
• Residual alveolar ridge
LIMITING STRUCTURES
• Labial frenum
• Labial vestibule
• Buccal frenum
• Buccal vestibule – Masseteric
notch
• Retromolar pad
• Alveolingual sulcus –
Retromylohyoid space
RELIEF AREAS
• Crest of residual alveolar ridge
• Mylohyoid ridge
• Mental foramen
• Genial tubercles
• Torus mandibularis
STRESS BEARING AREAS
• Primary – Buccal shelf area
• Secondary – Labial and lingual
slopes of the residual ridge

25. LABIAL VESTIBULE
It is the sulcus between the frenum's
The major muscle in this area
Orbicularis oris
Mentalis
25
Significance
The fibers of Orbicularis oris are horizontal, careful border
molding done it avoid overextension of denture
 Mentalis muscle due to its excessive activity results in short
flange which may not provide a real seal for the finished
denture
Labial and buccal borders are not as critical for border seal
because the drape of lips & cheeks create a facial seal

26. BUCCAL FRENUM
• It may be a single band or often two or more bands
• Usually in the area of first premolar
26
Significance
Oral activities in this area are horizontal as well as vertical
so wider clearance is usually needed

27. BUCCAL
VESTIBULE
• Extends posteriorly from buccal frenum to the outside back
corner of the retromolar pad
• The impression is always widest in this region since the buccal
flange swings wide into the cheeks
27
 Influenced by buccinator muscle
 Buccal flange may extend upto the external oblique
ridge
 The denture should cover the buccal shelf area
completely
 Distobuccal border at the end of buccal vestibule must
converge rapidly to avoid displacement by the contracting
masseter muscle

28. LINGUAL FRENUM
• A fibrous band of soft tissue that overlies the center of the
genioglossus muscle
• Anteriorly attached to the tongue
28
Significance
Inadequate clearance may lead to pain and dislodgement
of the denture

29. ALVEOLOLINGUAL SULCUS
• Space between the residual alveolar ridge and the tongue
• Extends from the lingual frenum to the retromylohyoid curtain
29
Divided into three parts
• Anterior region or The Sub Lingual Crescent area
• Middle region or The Mylohyoid area
• Posterior region or Retromylohyoid fossa

30. ANTERIOR LINGUAL VESTIBULE
 Extends from lingual frenum to premylohyoid fossa
 Mainly influenced by genioglossus and lingual frenum
 Lingual border of the impression should contact the mucous membrane
of the floor of the mouth when the tip of the tongue touches the upper
incisors
 Lingual flange should be shorter anteriorly than posteriorly
30

31. MYLOHYOID AREA
 Extends from premyohyoid fossa to the distal end of the mylohyoid ridge
 Mainly influenced by mylohyoid muscle
 Lingual flange should slope toward tongue
Aids in stabilizing the denture as the tongue rests over it
 Provides space for raising the floor of the mouth without displacing the
denture
 Peripheral seal is maintained
during function
31

32. RETROMYLOHYOID FOSSA
 The flange passes into the retromylohyoid fossa
 Since it is not acted upon by the mylohyoid in the retromylohyoid
fossa it turns laterally toward the ramus to fill the fossa & complete
the typical ‘S’ form of lingual flange
32

33. NEIL’S LATERAL THROAT FORM
Described that the lingual flange could have three possible
lengths depending on the anatomic attachments of the adjacent
structures
Class I – anatomical structures can accommodate a long and wide
flange
Class II – half as long and narrow as class i
Class III – has a minimum length and thickness
33

34. RETROMOLAR PAD
A triangular soft pad of tissue at the distal end of the lower ridge
Significance
Posterior seal of mandibular denture
34

35. DISTAL BORDRES
The distal border of the denture is limited by
• Ramus of the mandible
• Buccinator muscle
• Internal and external oblique ridge
Significance
Overextension at this border causes soreness & also limits of buccinator muscle
35

36. BUCCAL SHELF AREA
• Primary area of support of mandibular denture
• It is between the mandibular buccal frenum & anterior edge of
masseter muscle
It is bounded
Medially – crest of alveolar ridge
Laterally – external oblique ridge
Distally – retromolar pad
36
Significance
Bone of the buccal shelf is covered by a layer of
cortical bone & also it lies at right angles to the vertical
occlusal forces , makes it most suitable primary stress
bearing area

37. RESIDUAL ALVEOLAR
RIDGE
Anterior alveolar ridge tends to resorb & hence it is considered
as secondary stress bearing area
Posterior alveolar ridge can also be considered a primary stress
bearing area , however often the ridge is poor and the buccal shelf
must assume the major role
37

38. MYLOHYOID RIDGE
The distal end of the ridge is close to the crest of the ridge & anterior aspect close to the lower border
of mandible
Significance:
• A prominent sharp ridge interfere with the
development of correct lingual flange &
cause pain especially during mastication
•Proper relief should be given
38

39. MENTAL FORAMEN
 As resorption occurs mental foramen will come to lie closer
to the crest of residual ridge
 Unless relief is provided the nerves and blood vessels will
get compressed
39

40. GENIAL TUBERCLE
• They lie away from the crest of ridge
• Due to resorption they also become increasingly prominent
& hence relief is essential to avoid complications
40

41. IMPRESSIONS FOR COMPLETE
DENTURE
41

42. DEFINITIONS
IMPRESSION – A negative likeness or copy in reverse of the surface of an object, an imprint of the
teeth and adjacent structures for use in dentistry (GPT 9)
42

43. PRINCIPLES OF IMPRESSION MAKING
43
1. Tissues must be healthy, before impression making
2. Proper space must be provided for selected impression material
3. Tray and impression material should be dimensionally stable
4. For correct positioning of tray, a guiding mechanism should be provided
5. Impression should be adequately extended to include the entire basal seat area as dictated by
limiting and supporting structures
6. A border moulding must be performed in harmony with anatomical and physiological
limitations of the oral structures
7. Impression must be removed without damage to the oral structures
8. The tissue surface of impression and intaglio surface of the denture must be coincide

44. OBJECTIVES OF IMPRESSION MAKING
44
1. Retention
2. Stability
3. Support
4. Preservation of residual structures
5. Aesthetics

45. OPERATOR POSITION FOR MAXILLARY
IMPRESSION
CORRECT INCORRECT
45

46. OPERATOR POSITION FOR MANDIBULAR IMPRESSION
CORRECT INCORRECT
46

47. TECHNIQUES
• Open mouth technique
• Mucocompressive
• Mucostatic
• Selective pressure
• Closed mouth technique
47

48. PRIMARY IMPRESSION
• It records the useful anatomy of the edentulous mouth so that a model can be cast on
which an accurately fitting special tray can be made.
Materials used:
Alginate
Impression compound
48

49. • IMPRESSION IN COMPOUND TRAY
3. Compound placed in the tray.
1. Modelling compund. 2. Softenend in water bath
and kneaded.
TECHIQUE FOR PRIMARY IMPRESSION
49

50. 5. Should cover mylohyoid ridge and
external oblique ridge.
4. Molded with fingers to ridge form.
6. Gently warmed over a flame. 7. Before insertion, tempering in
warm water bath.
50

51. 9. Patient instructed for Tongue
movements and to purse lips.
8. Tray should be gently seated.
11. Any short areas can be
remolded.
10. Impression should cover all
denture bearing area.
51

52. • PRIMARY IMPRESSION IN ALGINATE
4. Tray should be adjusted by
bending .
1.Selection of stock tray. 2. Position borders at hamular notches.
3. Lift the tray anteriorly, 3-5 mm
space for impression material.
52

53. 5. Border of ray should be short of
tissue reflection.
6. Adequate clearance in frenal
areas.
7. Tray should be
smoothened.
53

54. 10. Tissue stop in central portion of
tray.
8. Deficient borders corrected by adding
utility wax.
9. Tray extension in buccal space
and tissue side of posterior border.
54

55. 11. Location of hamular notches. 12. Mark the vibrating line.
13. Some alginate to be placed in
vestibule.
14. Alginate to be placed in deepest
part of palate.
55

56. 15. Tray to be rotated into the mouth and
seated first at the back of the mouth. 16. Upper lip elevated.
17. Tray is held in the mouth.
18. Labial and buccal borders to be
molded.
56

57. 19. Completed maxillary primary Impression with rounded
and molded peripheries.
57

58. • MANDIBULAR ALGINATE IMPRESSION
3 . Tray should cover retromolar pad
and rest against external oblique
ridge.
1. Metal edentulous tray
2. Retromolar pad should be
identified
58

59. 4. Bending and cutting the tray for adjustment.
5. Adding utility was to
extend lingual border.
59

60. 7. Patient told to do tongue movements.
6. Patient told to raise the tongue and
tray is rotated in the mouth.
8. Gently mold the labial and buccal areas.
60

61. • Completed Mandibular Primary Impression
61

62. CLOSED MOUTH TECHNIQUES
• The denture has more accurate fit during mastication.
• Impression material coated at bases of the blocks and patient told
to close in retruded contact position.
• Patient given small amount of water to rinse. This captures the
normal movements of the surrounding musculature.
Material :
• thin zinc oxide eugenol,
• light body silicone.
62

63. CLOSED MOUTH TECHNIQUE
Drawbacks
• Maxillary Disto buccal space is not recorded in function.
• Viscous impression material can lead to increase in vertical
dimension.
Advantages
• Discrepancies in the jaw relations, resulting from points of
premature contact of the rims are eliminated.
• Masseter muscle can be recorded in function.
63

64. MUCO-COMPRESSIVE TECHNIQUE
• The impression material must be capable of viscous flow as it is
extruded under pressure from between the tray and the tissue
surface
Materials used
• Impression compound
• High viscosity silicones
• Stiff zinc oxide eugenol
64

65. MUCOSTATIC TECHNIQUE
• Use a very fluid impression material, and use minimal pressure while it sets.
• Minimal pressure technique
• By Page
• Eg. Impression plaster, Alginate
65

66. SELECTIVE PRESSURE TECHNIQUE
• It is a combination of extension for maximum coverage within tissue
tolerance with light pressure or intimate contact with the movable,
loosely attached tissues in the vestibules.
• The impression is refined with a minimum of pressure.
• By Boucher
66

67. • Impressions For Complete Dentures , Bernard Levin
• Essentials Of Complete Denture Prosthodontics , Second Edition ,Winkler
• Textbook Of Complete Denture Prosthodontics, Boucher
• Significance Of Anatomical Landmarks In Complete Dentures, Jpd ,1964,vol :14
• Reliability Of The Fovea For Determining The Posterior Border Of The Maxillary Denture,
Jpd,1980 ,Vol :43
• Analysis Of The Posterior Palatal Forms Related To Complete Dentures, Jpd ,1982 ,Vol:47
• Location And Preparation Of Posterior Palatal Seal ,Jpd ,1983 ,Vol :49
• Relationship Of The Maxillary Canine To Incisive Papilla , Grove ,Jpd , 1989 ,Vol: 61.
• Frequency And Locations Of Traumatic Ulcerations Following Placement Of Complete Dentures,
Kivovics, Ijp ,Aug 2007
• Significance Of Fovea In Complete Dentures, Lye , JPD , 1975 ,VOL :33
• Variable Denture Limiting Structures Of The Edentulous Mouth ,Jpd , 1966 ,Vol : 16
• A Comparison of The Retention Of The Retention Of The Complete Denture Bases Having Different
Types Of Posterior Palatal Seal, Avant , JPD , 1973 ,VOL :29
67
REFERENCES