1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 7

Bone

Periost

Submucosa

Fig. 1.6 The maxilla shows a volumetric shrinkage and maxillary

sinus are separated by only a thin layer of bone from the oral mucosa

The maxilla shows a volumetric shrinkage, maxillary Mucosa

sinus is separated by only a thin layer of bone from the oral
mucosa. The mandibular bone loss is four times more than
the loss in the maxilla. This situation cause collapses in the
face and lips, shrinkage in the mouth and wrinkles starting
from the corners of the lips in elderly patients who do not use
denture (Fig. 1.6).
The harmony of the present denture with the anatomical
structures and the health of the soft tissues informs us in Fig. 1.7 Mucous membrane
advance about the prognosis of the treatment. In addition,
detailed knowledge of the anatomical structures will help to
provide stability, retention, aesthetics and comfort success- density of the submucosa directly support the soft tissues
fully during impression taking. under the prosthesis, and in many cases submucosa forms the
larger part of the mucous membrane. In a healthy mouth,
submucosa adheres to the bone by means of the periosteum
1.1.2  natomical Landmarks in Relation
A and is generally resistant against the pressure of the denture
to Complete Denture (Fig. 1.7). If the submucosa is tight, it resists the pressures; if
it is loose, thin, traumatized and mobile, it will be weak
As an architect tries to get information about the place of the against pressures.
building that will be constructed, a skilled dentist should Oral mucosa is examined in three groups:
evaluate the anatomy of the face and mouth before fabricat-
ing a denture. In this section, anatomical structures in rela- 1. Masticatory mucosa
tion to complete denture will be discussed. 2. Lining mucosa
3. Specialized mucosa
1.1.2.1 Mucous Membrane
Denture base plate is placed over mucous membrane acting Attached gingiva, residual ridge and hard palate are cov-
as a pillow between supportive bone and denture base plate. ered by masticatory mucosa which is covered by a keratin-
Mucous membrane consists of two layers: mucosa and sub- ized layer changing due to the thickness of the outer surface
mucosa layers. Mucosa is formed of an outer layer of strati- (Figs. 1.8 and 1.9). Specialized mucosa covers the dorsal
fied squamous epithelium and an underlying layer of dense surface of the tongue and it is keratinized (Fig. 1.10). Lining
connective tissue (lamina propria). mucosa is lacking in keratinized mucosa. Lips, cheeks, ves-
Submucosa is formed of connective tissue containing fat, tibular spaces, alveololingual sulcus, soft palate and unat-
glands and muscle cells and provides the transition of blood tached gingiva on the slopes of the residual ridge are covered
and nerve cells to support the mucosa. The thickness and by lining mucosa (Fig. 1.11).
8 Y. K. Özkan et al.

Figs. 1.8 and 1.9 Masticatory mucosa on maxilla and mandible

The hard palate keratinized tissue and the median palati-

nal raphe are rather thin and need relief to not cause pressure
from the denture. The horizontal parts of the hard palate are
the primary stress-bearing areas, while the rugae regions cre-
ate an angle with the residual ridge and the secondary stress-
bearing area. The part in the rest of the lingual gingival
margin is called palatal gingival vestige. This region assists
in the position of the posterior teeth during denture
fabrication.
On residual ridges, the mucous membrane is keratinized
tissue and is tightly attached to bone. There are no glands but
there are dense collagen fibers. It is relatively thin but still
sufficient for the prosthetic support. The residual crest is
prone to resorption and is commended a secondary stress-
bearing area. The inclined facial surfaces are loosely
attached, cannot resist the pressures and provide little sup-
Fig. 1.10 Specialized mucosa
port to the denture.

1.1.3  natomical Landmarks in Relation

A
to Mandibular Denture

Anatomical landmarks in relation to mandibular denture are

explained in details in Figs. 1.12, 1.13 and 1.14. The consid-
erations for the mandibular impressions are generally similar
to those of maxillary impressions with a few inceptions. The
basal seat of the mandible is different in size and forms its
maxillary counterpart. The submucosa in some parts of the
mandibular basal seat contains anatomic structures different
from those in the upper jaw. The nature of the supporting
bone on the crest of residual ridge usually differs between
the two jaws. The presence of the tongue complicates the
impression procedures for the lower denture.
The available area of support from an edentulous mandi-
Fig. 1.11 Lining mucosa ble is 14 cm2 while the same for the edentulous maxilla is
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 9

8
6
7 7
4
9

5
3
9

10 10
11 11
2

Fig. 1.12 1: Retromolar pad, 2: buccal shelf, 3: posterior alveolar

ridge, 4: anterior alveolar ridge, 5: lingual frenum, 6: labial frenum, 7:
buccal frenum, 8: labial vestibule, 9: buccal vestibule, 10: masseter
muscle area, 11: lingual vestibule

1
6 4 3
7
2

8 9

Fig. 1.13 Mandibular ridge (lateral view): 1: retromolar pad, 2: buccal

shelf, 3: posterior alveolar ridge, 4: anterior alveolar ridge, 5: lingula
frenum, 6: labial frenum, 7: buccal frenum, 8: labial vestibule, 9: buccal
vestibule

Figs. 1.15 and 1.16 Supporting tissues of the mandibular jaw: 15

1 Buccal shelf and 16 alveolar ridge

6
4 5
3 12

13
11

Fig. 1.14 Mandibular ridge (lingual view): 1: retromolar pad, 3: poste-

rior alveolar ridge, 4: anterior alveolar ridge, 5: lingual frenum, 6: labial
frenum, 11: lingual vestibule, 12: mylohyoid ridge, 13: submandibular
fossa

24 cm2. Supporting tissues of the mandibular jaw are shown

in Figs. 1.15 and 1.16.

1.1.3.1 Crest of the Mandibular Ridge

The crest is covered by the fibrous connective tissue, but in
many mouths the underlying bone is of the cancellous type
without a cortical bony plate covering. The fibrous connec- Fig. 1.17 Mandibular crest
tive tissue is favourable for resisting the externally applied
forces, such as the denture. However, with the underlying
cancellous bone, this advantage is lost (Fig. 1.17).
10 Y. K. Özkan et al.

1.1.3.2 Retromolar Pad (Pear-Shaped Pad) by the temporalis tendon, laterally by the buccinators and
The retromolar pad, as described by Sicher, is described as the medially by the pterygomandibular raphe and the superior
soft elevation of mucosa that lies distal to the third molar constrictor muscle. The retromolar pad is quite important for
(Figs. 1.18 and 1.19a). It contains loose connective tissue with the support and the peripheral seal. The mucosa of the retro-
an aggregation of mucous glands and is bounded posteriorly molar pad is usually attached gingiva. When dried with a

a b

c
d

Fig. 1.18 Retromolar pad. (a) In the mouth, (b) on the impression, (c, d) on the model, and (e) on the denture
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 11

a b

Fig. 1.19 (a) Retromolar pad, (b) the relation between occlusal plane and retromolar pad

Figs. 1.20 and 1.21 Buccal shelf is 4–6 mm in width on an average maxilla

gauze pad and examined, the mucosa is hard, smooth and dull. 1.1.3.3 Buccal Shelf Area
The lower denture should reach the distal side of the retromo- The buccal shelf is the bone area between the extraction sites of
lar pad since it is important for the support and the peripheral the molars and the external oblique line. In other words, the area
seal. The upper border of the retromolar pad or the 2/3 upper between the mandibular buccal frenum and the anterior edge of
part determines the occlusal plane (Fig. 1.19b). Approximately the masseter is known as the buccal shelf. It is bounded medially
2/3 of the retromolar pad should be covered by the denture; on by the crest of the residual ridge, anteriorly by the buccal fre-
the distal 1/3 is a loose tissue covered by salivary glands. Since num, laterally by the external oblique line and distally by the
the retromolar pad is rarely resorbed and decisive for the retromolar pad. The buccal shelf forms the primary support for
occlusal plane, it is an important element design. the mandibular denture as it is made primarily of cortical bone
If the residual ridge is weak and the peripheral seal is dif- and generally lies perpendicular to the occlusal plane. The width
ficult, it will be advantageous to extend the denture as a drop of the buccal shelf area can range from 4 to 6 mm on an average
shape through the distal side of the pear-shaped pad. The drop mandible (Figs. 1.20 and 1.21) to 2–3 mm or less in a narrow
shape is achieved by carving the model 1.5 mm in depth and mandible (Fig. 1.22). The buccal shelf is resistant to resorption
1.5 mm in width. due to the durable cortical bone structure and the stimulation of
12 Y. K. Özkan et al.

OCCLUSAL FORCES

TRANSFER OF
THE FORCES

Fig. 1.22 Buccal shelf area in a narrow mandible Bu

cca
l ra
ph
e

Fig. 1.24 Masticatory forces reach the buccal shelf area with a right
angle

the load-bearing capacity of the buccal flange is great and pro-

vides excellent support against the occlusal forces (Fig. 1.24).
Some of the fibers of the buccinator muscle are under the buccal
flange; the insertion area of this muscle is close to the crest of
the ridge. The attachment of the buccinator muscle lies parallel
to the bone; therefore the denture is not effected by the contrac-
tions of the muscle.

Fig. 1.23 Buccal shelf area

1.1.3.4 Posterior Alveolar Ridge
buccinator muscle attachments (Fig. 1.23). When the alveolar The posterior alveolar ridge is considered the primary
ridge is flat, the buccinator muscle mostly adheres to the crest of area of support. However, when the residual ridge is
the ridge. Since the buccinator muscle is relatively resilient and weak, the buccal shelf plays a major role for support
inactive and the fibers of the muscle lie horizontally, it is cov- (Fig. 1.25).
ered by the denture in this region. The buccal shelf area is a key
factor for the stability of the mandibular dentures due to its large 1.1.3.5 Anterior Alveolar Ridge
support area. Although all the slopes of the alveolar ridges are The anterior alveolar ridge lies between the extraction
essential, buccal shelf area which is large, flat and more resistant sites of canines. This area is prone to resorption under
to occlusal forces is the most important of all the regions. As the forces and should be considered as a secondary support
masticatory forces reach a right angle to the buccal shelf area, area (Fig. 1.26).
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 13

a a

b b

c c

Fig. 1.25 (a–c) Posterior alveolar ridge area in different cases Fig. 1.26 (a–c) Anterior alveolar ridge area in different cases
14 Y. K. Özkan et al.

1.1.3.6 Lingual Frenum sometimes two or more bands and wider frenum can be
Lingual frenum is a formation connecting the floor of the observed (Fig. 1.27). The related area of the mandibular den-
mouth to the alveolar mucosa and is located over the ture is prepared accordingly. The dentist should pay attention
Genioglossus muscle. As the frenum consists of fibrotic con- to this area during taking impression and adjusting the den-
nective tissue, they do not contract and expand as the mus- tures. Labial frenum is mostly single narrow fibrotic band
cles. They attach closely to the crest of the ridge. The lingual but occasionally may consist of two or more bands
frenum is usually composed of a single narrow band, but (Fig. 1.28). On the other hand, lingual flange closure is rather
important for the retention of the denture. Large opening of
the frenum area on the denture will disrupt retention. When
a the lingual frenum is short, the patient cannot move his
tongue anteriorly. In this case, a surgical procedure called
frenectomy can be necessary.

1.1.3.7 Labial Frenum

Labial frenum is a single narrow fibrotic band but occasion-
ally may consist of two or more bands (Fig. 1.29). It is
shorter, larger and less prominent when compared to the

Fig. 1.28 Short lingual frenum and irritation caused by insufficient

reduction

Fig. 1.27 (a–c) Lingual frenum in different structures Fig. 1.29 Labial frenum
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 15

LABIAL FRENUM
a

Fig. 1.30 Widening the labial area on the denture

Fig. 1.31 Buccal frenum

maxillary labial frenum. The activity of this area tends to be

vertical, so the labial notch on the denture should be narrow
(Fig. 1.30).
e
1.1.3.8 Buccal Frenum
Buccal frenum is a single or double, wide or sharp V-shaped
connection starting from the posterior of the canine and lying
anteroposteriorly. It is closely related to the triangularis mus-
cle (Fig. 1.31). Buccal frenum is generally on the level of
first premolar, and it is the tendon attachment of the buccina-
tor muscle. It is a single fibrotic band but occasionally may
consist of two or more bands (Fig. 1.32a–e). The oral activi-
ties in these areas are horizontal as well as vertical (i.e. grin-
ning and puckering), thus needing wider clearance
(Figs. 1.33, 1.34, 1.35, and 1.36). The contour of the denture
should be a little narrow in this area due to the activity of the
depressor anguli oris muscle (Fig. 1.37).
Fig. 1.32 (a–e) Buccal frenum in different positions
1.1.3.9 Labial Vestibule
Labial vestibule is the area between the buccal frenums. If
the frenum is lacking or the locations are different, then it is
the area between the first premolars (Fig. 1.38). The lips extends through the buccal frenum. Labial vestibule area is
should be supported by the artificial teeth and acrylic resin in limited with the connection area of the mobile and immobile
the labial vestibule area. The posterior border of the area mucosa inferiorly, alveolar ridge medially and lip laterally.
16 Y. K. Özkan et al.

d Fig. 1.34 Insufficient reduction on the buccal frenum area

BUCCAL FRENUM

Fig. 1.35 The space prepared on the buccal frenum

Labial space

Buccal space

Fig. 1.32 (continued)

Fig. 1.36 The space prepared on the labial and buccal frenum

Fig. 1.37 Thinly prepared buccal flange border of the denture

Fig. 1.33 Sufficient reduction on the buccal frenum area

1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 17

Fig. 1.38 Labial vestibule area

Fig. 1.40 The muscles in relation to complete dentures

8

İncisive labii inferioris, the mentalis and the orbicularis oris

7
muscles are in that region so the denture should not be thick-
5 6
13 4 ened. The major muscle in this area is the orbicularis oris
muscle. Since the fibers of this muscle lie horizontally, the
borders of the impression should not be extended (Figs. 1.39
and 1.40). Mental muscle originating from the mental tuber-
3 cule unites with the orbicularis muscle in the lower lip. It is
1
a vertical muscle and is very active in some cases. This activ-
2 ity is very important for the border moulding procedures.
12 During taking impression, the lower lip should be slightly
pulled anteriorly. Pulling the lip severely will cause taking
3 the impression inaccurately, short labial flanges and loss of
the hermetic seal due to the narrowing of the area. The for-
9
10 mation of the other muscles effecting the mandibular flange
is also in this region, but they are considerably thin and have
11 minimal effect. The structure of the alveolar ridge is signifi-
cant for the border moulding. If the ridge is normal and fine,
the labial flange should be 1–2 mm (thick flange will inhibit
the lips) (Fig. 1.41). If the ridge is flat, the flanges should be
prepared thicker in order to provide hermetic seal and buccal
support (Fig. 1.42).

Fig. 1.39 The muscles in relation to complete dentures. 1 Buccinator,

2 modiolus, 3 orbicularis oris, 4 levator anguli oris, 5 zygomaticus
major, 6 zygomaticus minor, 7 levator labii superioris, 8 levator labii
superioris alaeque nasi, 9 depressor anguli oris, 10 depressor labii infe-
rioris, 11 mentalis, 12 risorius, 13 masseter
18 Y. K. Özkan et al.

Fig. 1.41 Labial border on a normal ridge

Figs. 1.43 and 1.44 Buccal vestibule area

Fig. 1.42 Labial border on a flat ridge

1.1.3.10 Buccal Vestibule

The width of this area depends on the buccal shelf and the buc-
cinator muscle. It is also known as buccal pouch or buccal
cavity, and the external oblique line which is a bony formation
is situated in this area. The buccal shelf which is also present
in the same area is a flat region and is used as a support area in
severely resorbed alveolar ridges (Figs. 1.43, 1.44, 1.45, and
1.46). In order to provide proper support in the buccal flange
area, the denture should be extended up to the outer border of
the buccal shelf and the external oblique line. This area can be
determined easily with palpation. In the external oblique area,
the denture flange border can be extended only 1–2 mm
(Fig. 1.47). The length of the buccal flange is not that much
critical for the peripheral seal. The force of the cheeks pro- Fig. 1.45 Buccal vestibule area on the model
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 19

1a
2

1b
1

2
1c

5 4
Fig. 1.46 Buccal vestibule area supported by the lips
Fig. 1.48 Major muscles effecting the labial and buccal flanges. 1
Buccinator muscle. a Superior fibers, b middle fibers, c inferior fibers,
2 orbicularis oris muscle, 3 modiolus, 4 depressor anguli oris, 5 mental
muscle

vides the facial seal. In some cases, buccinator muscle can be

active or strained; in this instance the entire buccal shelf can-
not always be covered. Buccinator muscle consists of three
muscles anatomically that have different innervations
(Fig. 1.48). The middle fibers form the most active muscle as
their main function is to control the food bolus during mastica-
Buccinator Muscle tion. The middle fibers unite diagonally in the corner of the
mouth and named as modulus forming the orbicularis oris.
The superior and inferior fibers are rather loose especially in
the beginning area. Buccinator muscle starts from the buccal
edges of the maxillary and mandibular ridges posteriorly and
from the pterygomandibular raphe distally. Therefore, buccal
shelf is completely covered in most instances.

1.1.3.11 The Effect Area of Masseter Muscle

It is the area behind the buccal region through the retromolar
External Oblique Line pad. The effect area of the masseter muscle lies on the lateral
side of the retromolar pad (Fig. 1.49). This is being called as the
“masseter groove”. This large and strong elevator muscle is
located over the buccinator muscle and when the masseter mus-
cle goes into action, it forms a straight line from the floor of the
retromolar pad to the distobuccal area of the denture (Fig. 1.50).
Border moulding should be made accurately in this area; other-
wise excessive length may cause pain. Thus, the denture base
should be narrow through the retromolar pad according to the
anatomy of this area. The masseter m ­ uscle is an elevator mus-
cle and closes the jaw; in such a situation, the denture should
not move. Short flanges will cause the loss of support and sta-
bility of the denture against lateral movements. An active mas-
Fig. 1.47 The relation of buccal vestibule area with buccinator muscle seter muscle will form a concavity on the distobuccal border,
and external oblique line and a less active muscle will end up with a convex border.
20 Y. K. Özkan et al.

1.1.3.12 Mylohyoid Ridge of the mandible. Determining the acuteness and promi-
The mylohyoid ridge is the origin of the mylohyoid muscle. nency of the mylohyoid ridge is important. A prominent
The distal end of the ridge is close to the crest of the alveo- mylohyoid ridge may prevent making a correct lingual
lar ridge while the anterior part is close to the lower border flange and may cause pain during mastication (Figs. 1.51,
1.52, and 1.53).

1.1.3.13 Pterygomandibular Raphe

Pterygomandibular raphe or ligament originates from the
pterygoid hamulus of the medial pterygoid lamina and
adheres to the distal edge of the mylohyoid ridge (Fig. 1.54).
It originates partially from the buccinator muscle laterally
and from superior constructor muscle mediolaterally. This
raphe which has features of a tendon is covered by a mucous
membrane called plica pterygomandibularis.
When the mouth is opened wide, it is stretched and a tense
plica comes out between pterygoid hamulus and the retro-
molar pad. The stretched raphe results in the rising of the
upper parts of the retromolar pad, and this is one of the fac-
tors effecting the stability of the mandibular denture nega-
tively. The pterygomandibular raphe may be very prominent
in some cases, so in the maxillary denture, a small notch can
Fig. 1.49 Masseter muscle effect area be prepared (Fig. 1.55).

Fig. 1.50 The effect of the

masseter muscle on the
distobuccal flange. a Middle
level activity will form a
straight line, b active muscle
will form a concavity, c
inactive muscle will form a
convexity

a b c

Figs. 1.51 and 1.52 The appearance of mylohyoid ridge area in the mouth
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 21

Fig. 1.53 Mylohyoid ridge area

Fig. 1.56 Submandibular fossa

Fig. 1.54 Pterygomandibular raphe

Fig. 1.55 Prominent pterygomandibular raphe attached to the buccal

frenum
Figs. 1.57–1.59 Submandibular fossa located under the mylohyoid
ridge
22 Y. K. Özkan et al.

Figs. 1.57–1.59 (continued) Fig. 1.62 The appearance of lingual vestibule on the model

1.1.3.15 Lingual Vestibule

It is impossible to achieve peripheral seal without an accu-
rate lingual flange. Many dentists are not aware of the sig-
nificance of the peripheral seal. The mandibular denture can
have a retention as much as the maxillary denture by provid-
ing an accurate peripheral seal. Therefore, learning the anat-
omy of the related area in details and using the most suitable
impression technique for the best seal in the lingual flange
area of the denture are required (Figs. 1.60, 1.61, and 1.62).
Figure 1.63 shows the old denture with short flanges and the
new denture with the extended flanges.
The big differences between lingual vestibular view and
the denture flanges emphasize on knowing the oral anatomy
and the necessity of using this information during taking
impression (Figs. 1.64 and 1.65). It can be easily examined
when divided into three areas.

1. Anterior Vestibule
Sublingual crest area or anterior sublingual gland area
(Fig. 1.66)
2. The Middle Vestibule
Mylohyoid area (Fig. 1.67)
3. The Distolingual Vestibule
Lateral throat form or retromylohyoid fossa (Fig. 1.68)
In order to understand the lingual area of the denture, pro-
vide retention and use the accurate impression techniques,
the anatomy of this area should be well-known.

1. Anterior Lingual Vestibule Sublingual Crest Area or

Figs. 1.60 and 1.61 Lingual vestibule area Anterior Sublingual Gland Area
This area extends from the lingual frenum to the mylohy-
1.1.3.14 Submandibular Fossa oid ridge which curves down below the level of sulcus.
Submandibular fossa is a concave area which is located dis- The depression of the premylohyoid fossa can be pal-
tally under the mylohyoid ridge in the mandible (Figs. 1.56, pated here. This area is mainly influenced by the genio-
1.57, 1.58, and 1.59). glossus muscle, lingual frenum and the anterior portion of
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 23

a b

Fig. 1.63 (a) A patient with a flat ridge, (b) old denture, (c) new denture, and (d) two different dentures
24 Y. K. Özkan et al.

7
3

1
2
Fig. 1.66 Anterior vestibule
Fig. 1.64 Anatomical structures effecting the lingual border of man-
dibular denture: 1 genioglossus muscle, 2 mylohyoid muscle, 3 sublin-
gual gland, 4 superior constructor muscle, 5 pterygomandibular raphe,
6 buccinator muscle, 7 palatoglossus muscle

1
13

Fig. 1.67 Middle vestibule

3

4
12 5

11
6
10

9
7
8

Fig. 1.68 Distolingual vestibule

ture over the genial tubercles instead of surgery or reduc-

Fig. 1.65 The cross-section of the mandibula on the distal of the first ing the denture flanges (Fig. 1.73). If the sublingual crest
molar and related structures. 1 Sublingual gland, 2 submandibular area has a flange as thick as possible, it can be a good
channel, 3 lingual nerve, 4 hyoglossus muscle, 5 hypoglossal nerve, 6 barrier for a better peripheral seal (Fig. 1.74). The length
lingual artery, 7 hyoid bone, 8 platysma muscle, 9 digastric muscle, 10
of the flange in this area can be adjusted depending on the
submandibular gland, 11 facial artery, 12 mylohyoid muscle, 13 bucci-
nator muscle tonus and the activity of the genioglossus muscle and the
lingual frenum.
2. Middle or Mylohyoid Vestibule
sublingual glands (Figs. 1.66, 1.69, and 1.70). Lingual Middle vestibule is the largest area and mainly influ-
frenum is superimposed over genioglossus muscle which enced by the mylohyoid muscles and somewhat by the
is small but strong (Figs. 1.71 and 1.72). The function of sublingual glands (Figs. 1.67, 1.75, and 1.76). The mylo-
these muscles is to upraise and move the tongue anteri- hyoid muscle is the largest muscle in the floor of the
orly. Genioglossus muscles are attached to the genial mouth whose principal function occurs during swallow-
tubercles which are small bone protuberances located ing (Figs. 1.77 and 1.78). Its intraoral appearance is mis-
close to the midline of the lower mandibular border. In leading because the membranous attachment makes the
such a case, it will be more favourable to extend the den- muscle appear as if it is horizontal when contracting. In
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 25

Figs. 1.69 and 1.70 Anterior lingual vestibule

Figs. 1.71 and 1.72 Lingual frenum superimposed over genioglossus muscle

a b

Fig. 1.73 (a) Genial tubercule and (b) inclusion of the genial tubercule inside the denture
26 Y. K. Özkan et al.

4-6 mm

Fig. 1.74 Thickening of the borders of the anterior lingual vestibule

Fig. 1.76 The appearance of the middle lingual vestibule on the model

Sublingual
Gland

A: In function

B: In the rest position

Mylohyoid Muscle in function

Hyoid
Bone
Mylohyoid Muscle in rest position
Fig. 1.75 Oral lingual vestibule
Figs. 1.77 and 1.78 The function of mylohyoid muscle

maximum contraction, the fibers are still in a downward eliminated. Many instances have shown that the man-
and forward direction and the denture can be extended dibular dentures do not have peripheral seal due to the
below the muscle attachments along the mylohyoid very short and thin flanges. The length and width of the
ridge. Contracted mylohyoid muscle can elevate the sub- mylohyoid flange is determined by the membranous
lingual glands and therefore lingual vestibule can be attachments of the tongue through the mylohyoid ridge
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 27

Fig. 1.79 The average length of the mylohyoid ridge

Fig. 1.81 The thickness of the mylohyoid edge should be 4–5 mm or
more in patients with flat ridge

III 2
II
I

Fig. 1.82 The classification of lateral throat form, 1 mylohyoid mus-

cle, 2 palatoglossus muscle, 3 superior constructor muscle, 4 pterygo-
mandibular raphe, 5 buccinator muscle

peripheral seal. The width of the flange should be

2–3 mm for a good ridge. If the ridge is flat, it is often
advantageous to make the thickness of the mylohyoid
flange as 4–5 mm or more (Figs. 1.80 and 1.81).
3. Distolingual Vestibule
This area is also called as lateral throat form or retromylo-
hyoid fossa (Figs. 1.82 and 1.83a). This anatomical area is
Fig. 1.80 The appearance of a flat ridge the least understood and the most misformed area. The lat-
eral throat form is bounded anteriorly by the mylohyoid
muscle, laterally by pear-shaped pad, posterolaterally by
and the width of the h­yoglossus muscle. The lingual superior constrictor muscle, posteromedially by palato-
flanges in the mylohyoid areas are formed by the func- glossal muscle and medially by the tongue. The parts of
tional, contracted or elevated positions of the mylohyoid the superior constrictor muscle, the stylopharyngeus, buc-
ridge. When the mylohyoid muscle is in rest position, copharyngeus and glossopharyngeus muscles, are thin and
there will be voids in those flanges. The average mylohy- easily relocated muscles. The so-called “s” curve of the
oid border is approximately 4–6 mm beyond the mylohy- lingual flange of the mandibular denture results from the
oid ridge (Fig. 1.79). Some patients have a lower mouth effect of strong intrinsic and extrinsic tongue muscles and
floor and require more extended flanges to achieve relocates the retromylohyoid borders laterally and through
28 Y. K. Özkan et al.

a a

b b

S curve

Fig. 1.84 Examining the distolingual area with (a) mirror and (b)
finger

the lateral throat form shortens when the tongue is in full

protrusion. By examining the anatomy and observing the
mouth carefully, it is proven that it is impossible to place
any denture material to an area without a sulcular space.
The simplest and most reliable diagnostic procedure is to
determine the depth of this area by using a mirror and a
finger (Fig. 1.84). During this procedure, lateral throat
form which usually has the same length and width with the
S curve
denture flange is determined by slight tongue movements.
Lateral throat form can be examined by dividing into
three different categories (Fig. 1.82).

Class III lateral throat form has minimum length and thick-
Fig. 1.83 (a) Distolingual vestibule and (b) the S curve on the man-
dibular denture ness. The flange usually ends 2–3 mm below the mylohyoid
ridge or sometimes just on the ridge. The thickness should
not be more than 2 mm, or if the flange ends on the mylohy-
the retromylohyoid fossa (Fig. 1.83b). The posterior bor- oid ridge, it can be finished by decreasing the thickness.
der of the mandibular denture is determined mainly by the Class I throat form indicates that the anatomical structures will
palatoglossus muscle and somewhat by weaker superior allow the formation of longer and wider flange so the longest
constructor muscle, and this area is called as posterior ret- flange of the denture is the retromylohyoid flange. The thick-
romylohyoid curtain. There are researches reporting that ness of the flange is usually 2–3 mm, but a thicker border of
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 29

Fig. 1.85 (a, b) Insufficient distolingual area on the denture

4–5 mm can be used for a better seal if the ridge is flat. The
retromylohyoid curtain area (the most distal border) should
be thinner, rounded and smooth and should have 2–3 mm
thickness in order not to affect the palatoglossus muscle.
Class II lateral throat form is about half as long and narrow
as Class I and about twice as long as Class III. Most of the
edentulous mouths have Class I and II lateral throat forms
while Class III form is observed rarely.

There is another important reason for the lingual flanges

extending fully into the lingual sulcus within anatomical and
functional limitations except peripheral seal. These flanges Figs. 1.86–1.88 The appearance of sublingual glands
provide curved surfaces for the tongue which also form the
force vectors keeping the lower denture in place. This area
should be extended posteriorly and inferiorly as much as 1.1.3.16 Sublingual Gland Region
possible. During the impression stage, the patient is asked to Sublingual gland lies over the mylohyoid muscle. They can
swallow and lick his/her lips. If the flanges are short due to be in different sizes and sometimes they seem to be higher
faulty impression or if they are not concave to be adaptable than the alveolar ridge (Figs. 1.86, 1.87, and 1.88). When the
with the tongue, the prosthesis will be unstable during tongue mylohyoid muscles are in function, they elevate the glands in
movements (Fig. 1.85). such a manner that the lingual vestibule disappears. Sublingual
30 Y. K. Özkan et al.

Fig. 1.91 Determining the irritated areas with pressure indicator paste

Fig. 1.89 A large concavity seen on the alginate impression created by

the sublingual gland

Fig. 1.90 Irritated sublingual glands

gland can be observed especially with a runny alginate in the

diagnostic impressions (Fig. 1.89). Despite the appearance
and size, sublingual glands are usually very soft and mobile.
As long as they are not rigid, glands are not taken into consid-
eration during taking impression. If the ­surface of the glands Fig. 1.92 The normal position of the tongue is the position where the
is irritated after the dentures are placed, the areas which are tip of the tongue is placed on the lingual side of mandibular anterior
exposed to excessive pressure are determined with a pressure teeth
indicating paste and trimmed (Figs. 1.90 and 1.91).
sus) that needs careful attention during the construction of
1.1.3.17 Tongue complete dentures. A very active tongue can move a well-
The tongue consists of muscles, fibers and muscular attach- fitting denture. Small or medium size of the tongue is not
ments (The genioglossus, the hyoglossus and the styloglos- usually considerable. Clinically, tongue position can be
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 31

evaluated by asking the patient to open just wide enough peripheral seal does not take place and the retention is
for a small portion of food and observing different posi- prevented.
tions of the tongue. The normal position of the tongue is The retruded position of the tongue which is found in
the position where the tip of the tongue is placed on the 35% of the general population allows an easier ingress of
lingual side of mandibular anterior teeth (Fig. 1.92). food and air underneath the lingual borders with the loss of
In the normal position, the tongue appears relaxed and peripheral seal. It is accompanied by a high mouth floor due
completely fills the lower arch with its tip contacting the lin- to the amount of tension in all the associated muscles. When
gual surfaces of the mandibular teeth (Fig. 1.93). This posi- the tongue is too big, the success of the complete dentures is
tion is the most suitable position to provide lingual peripheral negatively affected. The significance of the position and
seal. In this position, sublingual salivary glands and sur-
rounding tissues come into contact with the sublingual fold
and move to assist the denture flanges in forming the periph-
eral seal. The tongue is positioned backwardly in nearly 35%
of the patients while 65% of them have a normal tongue
position (Figs. 1.94 and 1.95). The retruded position of the
tongue causes the posterior and inferior movement of the
sublingual gland and prevents the seal between the sublin-
gual gland and the mucous membrane in the periphery of the
denture. Unless the tissue-denture flange contact is present,

Fig. 1.94 The position where the tongue is placed backwards

b

Fig. 1.93 (a, b) The normal position of the tongue is the position
where the tip of the tongue is placed on the lingual side of mandibular
anterior teeth
Fig. 1.95 The position where the tongue is placed backwards
32 Y. K. Özkan et al.

Fig. 1.96 Large tongue blocks the movements of the denture Fig. 1.99 Lingual torus

location of the tongue is usually neglected by the dentists

(Figs. 1.96, 1.97, and 1.98). This position can be improved
by giving information about the problem and tongue exer-
cises. Since it is difficult to solve this problem for many
patients with retruded tongue, the following procedure is
succeeded. A small exercise groove of 10 mm length, 2 mm
width and 2 mm depth which is prepared just below the ante-
rior central incisors on mandibular denture will relieve the
patients. The patient is instructed to keep the tongue on the
groove at all times except eating and speaking. The edges of
the groove are rounded in order not to irritate the tongue.
Most patients learn to keep the tongue in correct position in
a few weeks. Then the groove can be filled with autopoly-
merising acrylic resin.

1.1.3.18 Lingual Torus

These are bone protuberances generally observed in premolar
region mostly bilaterally but sometimes unilaterally
(Fig. 1.99). Tori are rarely growing structures that are covered
by a thin mucosa. They may cause pain and irritation by any
movement of the denture base. If torus exists, it is almost
impossible to provide peripheral seal. The patient should be
informed about the results unless surgical intervention is pos-
sible. In such a situation, the first choice is to cover the torus
on the height of contour and form a denture flange as thick as
the tongue allows. The level of the torus may be on the same
level with the ridge in severely resorbed jaws. The pressure
should be relieved in this area without impairing the hermetic
seal of the dentures; otherwise it should be surgically removed.

1.1.3.19 Sublingual Fold

Figs. 1.97 and 1.98 The movements of the tongue cause the denture
It is the area between the lower alveolar ridge and the sublin-
move gual salivary gland. The flanges of the denture extend through
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 33

b
Fig. 1.101 Sublingual fold does not support the impression tray in a
weak fold

Fig. 1.100 (a) Strong sublingual fold and (b) the relation of sublingual
fold with the tray during taking impression

this area. Sublingual fold area can be in different anatomical

forms, and it can be examined in two categories as well
Fig. 1.102 The fit of the denture base flange to the tissues is provided
formed and weak formed (Figs. 1.100 and 1.101). A well- successfully when the salivary glands are located posteriorly
formed sublingual fold area is located between mandibular
anterior ridge and sublingual salivary gland and thus can be
seen clearly. The fit of the denture base flange to the tissues other tissues. When a weak formed sublingual fold area is
is provided successfully when the salivary glands are located present, either sublingual gland tissues are not existing or
posteriorly (Fig. 1.102). they moved posteriorly. Therefore, it is not possible to
Peripheral seal is quite important in this area and should achieve peripheral seal owing to the collapse of the mouth
be absolutely created around the flanges. The level of the floor.
mouth floor in the sublingual fold area depends on the activ-
ity of the genioglossus muscle. 1.1.3.20 Buccal Fat Pad
The genioglossus muscle lies over the geniohyoid and The buccal fat pad is a posteriorly located pad on the cheek
the mylohyoid muscles and plays an important role in the consisting of connective tissues, and it covers the masseteric
constitution of this anatomical area due to its mobility. The notch area of the denture (Figs. 1.103 and 1.104). This tissue
movements of the tongue occurring in the posterior area by contributes to both retention and stability of the denture. If it
the contraction of the genioglossus muscle move the sublin- extends through the denture flange in the masseteric notch
gual gland tissues and remove the posterior border of the area, it helps the retention and stability of the denture
sublingual fold. The mylohyoid muscle doesn’t have an (Fig. 1.105). It indicates the position of the buccal fat pad
effect in this area due to its inferior position related to the during taking impression.
34 Y. K. Özkan et al.

1.1.3.21  ocal Anatomical Factors Effecting

L
the Prognosis of Mandibula
The retention and stability of a denture differ from patient to
patient and depend on both anatomical and physiological
factors. In Tables 1.2 and 1.3, the factors affecting the reten-
tion and stability of the denture are shown, and the degree of
prognosis is numbered.
With increasing age, the density of bone tissue lessens
and the cortical bone gets thinner. Then the denture support
capacity of bone decreases. The atrophy of alveolar ridges is
an occurrence in which the ridges lessen continuously
(Fig. 1.106). It is considered that different anatomical, meta-
bolic or mechanical factors are effective for this process.
Complete atrophy of the mandibular alveolar ridges is
observed in patients who have been using dentures for a long
time. There is no reliable way to decrease the alveolar ridge
atrophy in edentulous patients. However, it is estimated that
improving the metabolic changes and careful denture care
will have a positive effect. The first point that the dentists
should consider is the amount of residual ridge. If there is

Table 1.2 Anatomical prognosis of mandibular complete dentures

according to stability criteria (Halperin et al. Mastering the art of com-
plete dentures, 1988)
Stability criteria
Factors Good prognosis Bad prognosis
Buccal shelf support Flat and large Inclined, narrow and
area concave
Tongue position Normal Backward position
Buccal fat pad In the masseteric Not in the notch
notch of the denture
Tissue tonus Resilient cheek and Firm cheek and lip
Figs. 1.103 and 1.104 Buccal fat pad in the masseteric region, on the lip tissue tissue
ridge Tissue under the Firm, supported by Mobile, thin and
denture connective tissue inelastic
The distance between Sufficient Insufficient, surgery
arches in occlusal contraindicated
vertical height

Table 1.3 Anatomical prognosis of mandibular complete dentures

according to retention criteria (Halperin et al. Mastering the art of com-
plete dentures, 1988)
Retention criteria
Factors Good prognosis Bad prognosis
The structure of the Prominent Non-prominent fold
sublingual fold area
Tongue position Normal (the tip of the Backward position
lower teeth)
Buccal fat pad In the masseteric Not in the notch
notch of the denture
Tissue tonus Resilient cheek and Firm cheek and lip
lip tissue tissue
Tissue under the Firm, prominent Thin, inelastic
Fig. 1.105 Buccal fat pad in the masseteric region, on the impression denture mucosa mucosa
tray The distance between Sufficient Insufficient, surgery
arches in occlusal contraindicated
vertical height
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 35

Fig. 1.106 Severely resorbed mandibular alveolar ridge Fig. 1.108 The supporting areas for the maxillary denture

Incisal Foramen
Median
Maxiller Palatinal
Palatinal Raphe
Process

Palatinal Foramen Nasal Tuberosity

Fig. 1.109 The support of the maxillary denture

Other anatomical factors effecting the prognosis are the

structures of the sublingual fold and the buccal shelf, posi-
tions of the tongue and buccal fat pad and tonus of the tissues
supporting the denture.
Fig. 1.107 The appearance of the maxilla on the model

insufficient amount of bone, it will be very difficult to make 1.1.4  natomical Landmarks in Relation
A
a successful denture. At this point many dentists will decide to Maxillary Denture
that the patient will not be able to use a denture and they will
direct the patient to a prosthodontist. Seventy percent of During making a denture, before placement of the denture
complete denture patients can be successfully treated with- over supportive tissues, it should be considered that the form
out any difficulties. Majority of this 70% group have quite of denture flanges should be compatible with the normal
resorbed mandibula, but they can use their dentures comfort- function of surrounding structures.
ably. It should be taken into consideration that high and reg- Primary stress-bearing areas in the maxilla are hard pal-
ular-shaped alveolar ridges are not always required for ate and posterolateral slopes of residual alveolar ridge, while
denture success. Dental surgeons often perform augmenta- rugae, maxillary tuberosity and relief areas, incisive papilla,
tion and vestibule deepening operations to increase the ridge median palatinal raphe and fovea palatine are the secondary
height. But the height of ridge provided by such an operation stress-bearing areas (Figs. 1.107 and 1.108). The terminal
may not be sufficient for the prognosis of denture. Essentially support for the maxillary denture are the two maxillary bones
resorbed ridges provide more area for tooth arrangement and the palatinal bone. The palatinal processes of the maxilla
without reducing the retention and stability. join at the midline and form the median suture (Fig. 1.109).
36 Y. K. Özkan et al.

The locations of the anatomical landmarks in relation to

maxillary denture are shown in Fig. 1.110.

1.1.4.1 Labial Frenum

Labial frenum is a fibrous connective tissue in the midline
that may consist of two or more bands. There is no muscular
attachment so it does not activate any muscle (Fig. 1.111).
The frenum area on the denture should have sufficient width
and depth without preventing the movements of the lip. The
movements of the lip in this area are essentially vertical; then
the notch on the denture will be usually narrow (Fig. 1.112).

8
6
10
7 11
7
4
4
Fig. 1.112 The space prepared for the labial frenum on the denture
12 12 should be narrow

9 3 3
29
2

1 1

14
5 15 14 5

Fig. 1.110 The anatomical structures in relation to maxillary dentures:

1 tubers, 2 zygomatic process, 3 posterior alveolar ridge, 4 anterior
alveolar ridge, 5 hamular notch, 6 labial frenum, 7 buccal frenum, 8
labial vestibule, 9 buccal vestibule, 10 incisive papilla, 11 midline pala-
tal suture, 12 rugae, 13 torus area in the hard palate, 14 pterygoman-
dibular raphe, 15 fovea palatini

Figs. 1.113 and 1.114 Preparing a large labial space destroys the her-
Fig. 1.111 Labial frenum metic seal
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 37

The excessive lateral movements during border moulding most of the complete denture patients. If the anterior alveolar
will cause a wider labial notch on the denture (Figs. 1.113 ridge is fine, the labial flange should be approximately 2 mm
and 1.114). In such cases, if the patients have short and active or less (Fig. 1.117). Thickening of the flange will eliminate
lips, peripheral seal will be lost. the philtrum, so this will cause a flat lip. If the ridge is flat,
thickening of the flanges is necessary for peripheral seal, and
1.1.4.2 Labial Vestibule it is also important for lip support (Fig. 1.118).
The labial vestibule is the area between the right and left There are three points that should be considered:
frenum, or if the frenum is not present, it is the area between
the right and left premolars (Figs. 1.115 and 1.116). In this 1. The impression should be taken providing sufficient sup-
area, the biggest muscle of the lips, the orbicularis oris, port to the upper lip.
whose fibers lie horizontally exists; therefore border mould- 2. The labial flange of the impression must have sufficient
ing procedure should be performed carefully in order not to height to reflect the mucous membrane of the labial ves-
cause excessive length in the flanges. The primary muscles tibular space.
lifting the lips are the zygomaticus major and the levator 3. There must be no interference on the labial flange during
anguli oris. These muscles are considerably thin and weak in the movement of the lip.

Figs. 1.115 and 1.116 Labial vestibule area

Fig. 1.117 If the alveolar ridge is fine, the labial edge should be 2 mm Fig. 1.118 If the alveolar ridge is flat, thickening of the edges are nec-
or less essary for the hermetic seal and it is also important for the labial
support
38 Y. K. Özkan et al.

Figs. 1.119–1.121 Buccal frenum in different numbers and locations

1.1.4.3 Buccal Frenum 1.1.4.4 Buccal Vestibule

Buccal frenum is the part of a band starting from the maxilla, The buccal vestibule area extends from the buccal frenum to
continuing along the modiolus in the corner of the mouth and the hamular notch and can be examined in two parts as paratu-
reaching the buccal frenum in the mandibula. It may consist ber area and zygomatic arch area (Figs. 1.122 and 1.123). The
of one or two bands in different locations (Figs. 1.119, 1.120, space between the ridge and the cheek creates a suitable buc-
and 1.121). Related muscles are the buccinator, orbicularis cal flange area for the denture. Besides, the size of the buccal
oris and levator anguli oris. Several muscles unite in the cor- vestibule varies according to the contraction of the buccinator
ner of mouth and create a knot called the “modiolus”. muscle, the position of the mandible and the amount of maxil-
The caninus muscle attaches below the buccal frenum lary bone resorption. The distal end of the buccal flange of the
and effects its function. The orbicularis oris muscle pulls denture is adjusted when ramus and the masseter muscle are in
the buccal frenum anteriorly while the buccinator muscle function. The width of the buccal vestibule lessens as the man-
pulls it posteriorly. Buccal frenum move together with three dible moves forward. The width of the distal area of the buccal
muscles. The clearance of the buccal frenum should be more vestibule is lesser as well when the masseter muscle contracts
than the labial frenum because of the related muscles in this during clenching. Buccal vestibule area is mainly affected by
area. Insufficient clearance of the buccal frenum and the the modiolus, buccinator muscle and distally coronoid pro-
thickness of the buccal flange will cause the movement of the cess. The fibers of the ­buccinator muscle are quite loose and
denture when the patient smiles. The flange of the denture lie horizontally in the origin area (buccal alveolar bone through
should be adjusted in full depth and width functionally. Oral the apex of molars) so excessive length can be observed in the
activities in this area are vertical as well as horizontal like the impression. The masseter muscle extends over buccal muscle
mandibular buccal frenum. Due to the frequent activity of and is not as much effective on the maxillary impression as on
buccal frenum and modiolus, the flange thickness of the buc- the mandibular impression. During determining the width of
cal notch should be quite thin (approximately 2 mm). the area, the mouth should be examined separately when it is
1 Anatomical Landmarks and Age-Related Changes in Edentulous Patients 39

Fig. 1.124 Zygomatic arch zone

Fig. 1.125 Paratuber zone

the maxillary origin of the masseter muscle is processus zygo-

maticus, by the contraction of this muscle, buccinator muscle
and the denture flanges lean on this region because the fibers
of the buccinator muscle are attached to mucosa and alveolar
Figs. 1.122 and 1.123 Buccal vestibule zone
ridge on the level of the roots of premolars and molars.

wide open and almost closed. Therefore, the effect of ramus 1.1.4.6 Paratuber Area
should be determined. It is the region behind the zygomatic arch area. In the pos-
terior area, the fibers of the buccinator are attached to tuber
1.1.4.5 Zygomatic Arch Area region, while in the hamular notch area, the fibers are
Zygomatic arch area is the part just behind the buccal frenum attached to pterygoid bone (Fig. 1.125).Tuber area should
which extends through the zygomatic bone superiorly be prepared thick sometimes in order to achieve peripheral
(Fig. 1.124). Zygomatic process (molar) is located in the molar seal. All the labial and buccal flanges can be short because
region and does not require special care unless flat ridge exist. of the labial closure (facial seal). If the patient smiles
If the ridge is flat, zygomatic arch area should not be used as a excessively and air enters under the denture, the seal disap-
stress-bearing area during taking impression as the mucosa is pears. The thickness of the buccal flange in the tuber region
thin, does not flex and requires relief. The denture should be can be 2–3 mm or 3–5 mm. The thickness of the tuber area
trimmed slightly in the related area to prevent pressure. Since depends on the size of the tubers, the relation with the coro-