INTRODUCTION
Knowledge of the orofacial anatomy is
necessary for making impressions, recording
jaw relations, adjusting dentures, etc.; infact,
anatomy is involved in nearly every phase of
dentistry.
 It is necessary to review important structures
that are directly related to impression making.
 It is also important to know their function and to
be aware of anatomical variations.
 The mandibular denture poses a great technical
challenge for the dentist and often a significant
management challenge for the patient.

1.) The denture bearing are of mandible 12.25cm and compared to maxilla 22.96
Less capable of resisting occlusal forces
Maxilla22.96cm2
Mandible12.25cm2
2.) Nature of the bone – cancellous and porus
3.) Presence of tongue and its individual size , form, and activity complicates the
impression procedure
CORRELATION OF ANATOMIC LANDMARKS
LANDMARKS IN MOUTH












Labial frenum
Labial vestibule
Buccal frenum
Buccal vestibule
Residual alveolar ridge
Retromolar pad
Pterygomandibular
raphae
Retromylohyoid fossa
Lingual tuberosity
Alveolingual sulcus
Lingual frenum
Buccal shelf
LANDMARKS IN IMPRESSION












Labial notch
Labial flange
Buccal notch
Buccal flange
Alveolar groove
Retromolar fossa
Pterygomandibular notch
Retromylohyoid eminence
Lingual tubercular fossa
Lingual flange
Lingual notch
Buccal flange resting on
buccal shelf
LIMITING
STRUCTURES
1. Labial frenum
2. Labial
vestibule
3. Buccal frenum
4. Buccal
vestibule
5. Lingual
frenum
6. Alveolingual
sulcus
7. Retro molar
pads
8. Pterygomandib
ular raphe
SUPPORTING
STRUCTURES
PRIMARY
STRESS
BEARING
Buccal
shelf
area
SECONDARY
STRESS
BEARING
Crest of
alveolar
ridge
RELIEF
AREAS
1. Genial
tubercle
2. Torus
Mandibularis
3. Mental
foramen
LABIAL FRENUM
Active band
 Extension : labial aspect of residual ridge to
the lip
 Muscle attachment : Orbicularis Oris

•CLINICAL SIGNIFICANCE

During final impression this frenum is
recorded as LABIAL NOTCH

Recorded : lifting the lower lip outward ,
upward and inwards

The denture should be carefully fitted around
to maintain the seal without causing
soreness.
LABIAL VESTIBULE

Extension: runs from the
labial frenum to the buccal
frenum between the residual
alveolar ridge and lip .
. Muscle attachment :
ORBICULARIS MUSCLE and
THE INCISIVE LABI
INFERIORIS (which are fairly close to
the crest ridge)

Active Muscle : MENTALIS
MENTALIS

It originates from mental tubercles and
inserts into the lower lip
CLINICAL SIGNIFICANCE

The extent of the denture
flange is critical

The muscle of the lower lip pull
actively across the denture
border, polished surfaces and
teeth

The borders if made thick the
denture will displace due to
stretching of orbicularis muscle
on the wide opening of mouth
Narrowest in ant.
Labial region
BUCAAL FRENUM
Fibrous Band
 Separates labial and
buccal vestibule

Muscle attachment :
Depressor Anglui Oris
•Clinical significance
the cheek is lifted outward,
upward, inward, backward, and
forward to simulate movement of the
frenum.
MOVEMENTS :
Frenum should be recoded as BUCCAL NOTCH.
BUCCAL
NOTCH
BUCCAL VESTIBULE
EXTENSION:
Anteriorly : Buccal Frenum
Posteriorly : Retromolar pad
 MUSCLE ATTACHMENT :
Anteriorly : Buccinator
Posteriorly : Pterygomandibular Raphe

( their lower fibres gets attached to buccal shelf
area and external oblique ridge )
CLINICAL SIGNIFICANCE
This area remains an
important esthetic
consideration because
when smiling the dark
space BUCCAL CORRIDOR.

Distobuccal border is
governed by masseter
and buccinator muscle .
(when the masseter muscle contracts, it pushes
inward the buccinator muscle = masseter notch )
IMPRESSION IS
WIDEST IN THIS
AREA
MOVEMENTS
 The effect of masseter muscle is
recorded by asking the patient to exert
a closing force while the dentist exerts
a downward pressure on the tray.
 For buccal flange, cheek is moved
outward, upward, and inward.

LINGUAL FRENUM
mucous membrane fold
seen on elevation of the
tongue
 This anterior portion of the
lingual flange is called sublingual crescent area.
CLINICAL SIGNIFICANCE
 Tongue tie .
 The patient is instructed to wipe
his lower lip from side to side
with the tongue tip.

RETROMOLAR PAD AREA


defines the posterior limit.
Triangular soft pad of tissue at distal end
of lower ridge
JACOBSON T.E, KROL A.J A CONTEMPORARY
REVIEW OF THE FACTORS INVOLVED IN THE
COMPLETE DENTURES . PART III: SUPPORT .
J PROSTHET DENT 1983;49(3): 306-313
PEAR SHAPED PAD AREA – keratinized
Residual scar of the third molar
 Not a favorable denture bearing area
Associated with – Buccinator(from buccal
shelf) , Superior Constrictor , Temporalis and
firmly bound Masticatory musosa .
If the denture gets short : more rapid resoption
and poor settling of the denture base is seen
The junction between the pear shaped pad
and the retromolar pad demarcates the
distal border of the properly extended
mandibular Complete Denture
CLINICAL SIGNIFICANCE

Helps in maintaining the occlusal plane by
posterior teeth arrangement .

Teeth should not be placed on the
retromolar pad.

Denture base should extend on posterior
two third over the retromolar pad
PTERYGOMANDIBULAR RAPHE

The pterygo mandibular raphe or ligament
originates from the pterygoid hamulus of
medial pterygoid plate and attaches to distal
end of mylohyoid ridge.
Raphe is a tendinous insertion of two
muscles
 The superior constrictor is inserted
posteromedially
 Buccinator is anterolaterally
inserted

LINGUAL BORDER
Less resistance than labial and buccal
borders
 Over extension easily causes dislodgment
and soreness
 Action of mylohyoid muscle is an important
consideration here

MYLOHYOID MUSCLE

Forms the complete roof of the floor of the
mouth

Extension :
Medially: it combines with the fibres from the
opposite side
Posteriorly: extend till hyoid bone

INFLUENCE ON THE BORDERS.
JACOBSON T.E, KROL A.J A CONTEMPORARY
REVIEW OF THE FACTORS INVOLVED IN THE
COMPLETE DENTURES. PART II: STABILITY
1983;49(3): 165-172
The lingual slope approaches 90 to the
occlusal plane which enables resistance
towards horizontal forces
 When contracted the anterior mylohyoid
muscle tenses the floor and limits the
extension
 Any flange below mylohyoid must extend
incline medially to allow the mylohyoid

EXTENSION OF FLANGE WRT TO MYLOHYOID
MUSCLE
1.) flange below the ridge : direct medially towards the muscle guides the tongue
to rest on it
2.) flange above the ridge : vertical forces might break the seal . Leads to
displacement
3) Flange below the ridge and in the undercut : causes soreness
RETROMYLOHYOID FOSSA
Area beyond mylohyoid
muscle.
 INFLUENCE ON THE
LINGUAL FLANGE.
 S – SHAPED CURVE .
 Boundaries
RETROMYLEHYOID
CURTAIN

RETROMYLOHYOID CURATIN
Posterolateral portion : overlies superior
constrictor muscle
 Posteromedial portion : covers
palatoglossal muscle and lateral surface
of the tongue
 Inferior wall : overlies submandibular
gland

ALVEOLINGUAL SULCUS
Space between residual alveolar ridge and
the tongue
 Extension : Lingual Frenum to
Retromylohyoid Curtain

THE ANTERIOR REGION
Extension :
Lingual frenum to the mylohyoid ridge curves above
the sulcus

A depression is seen premyloid fossa which is
recorded as Premylohyid Eminence in the impression
About the flange
 It should touch the floor of the mouth when asked to
touch the tongue at the anterior ridge
 It gets larger when extends into premylohyoid fossa
THE MIDDLE REGION
Extensions :
from the premylohyoid fossa to the distal end of
the mylohyoid ridge.
About the flange:
 Shallower
 Slope medially
 Can extend below the ridge
 Tongue rests on the flange for stability and
peripheral seal
THE POSTERIOR REGION

The denture flange in this region should turn
laterally towards the ramus of the mandible
to fill up the fossa and complete the typical
S-form of the lingual flange of the lower
denture.
CLINICAL SIGNIFICANCE

Patient is asked to Protrude the tongue out
- this gives the length of the flange
Patient is asked to touch the cheeks with the
tongue
- width Of the flange
Action :
This activates the mylohyoid muscle

Raises the floor of the mouth
And helps in maintaining seal and stability by
recording the borders

Finally, the patient is asked to open wide. If the
tray is too long, a notch will be formed at the
posteromedial border of the retromolar pad,
indicating encroachment of the tray on the
pterygomandibular raphe, and the tray must
be adjusted carefully
BUCCAL SHELF AREA
The area between the buccal frenum and
the anterior border of masseter
Boundaries
 Laterally - external oblique line
 (Medially) internally- the slopes of residual
ridge,
 Anteriorly - buccal frenum
 Posteriorly - retro molar pad.
REASONS THAT MAKES IT PRIMARY
STRESS BEARING
The structure of the bone – compact bone
 The occlusal forces – falls perpendicular

JACOBSON T.E , KROL A.J . A
CONTEMPORARY VIEW OF THE FACTORS
INVOLVED IN COMPLETE DENTURES.
PART III: SUPPORT. J PROSTHET DENT
1983;49(3): 306-313
 Covered by mucosa and sub mucous layer
of glandular connective tissue

Buccinator muscle fiber attaches inferiorly
to buccal shelf

Fibres runs longitudinally anteroposterially
permitting to rest on the muscle without
displacement.
CREST OF ALVEOLAR RIDGE
Secondary Support Area:
a)
b)
c)
d)
Lack of muscle attachment
Presence of cancellous bone
Porosity and roughness
Rapid resorption
MYLOHYOID RIDGE
Runs along lingual
surface of mandible
.
 ANTERIORLY :
attached to
mylohyoid muscle
& lies close to the
inferior border of
mandible.
 POSTERIORLY –
superior surface
Sharpness is hidden by overlying THIN SOFT
of residual ridge
TISSUE

THEREFORE relived
MENTAL FORAMEN
Lies b/w 1st & 2nd premolar region labially.
 Opening for mental nerves & vessels.
 CLINICAL SIGNIFICANCE –
Due to ridge resorption, it may lie close to
crest of the ridge ridge.


Denture Base may exert Pressure over nerves
( if not relieved)
may produce
parasthesia of lower lip
GENIAL TUBERCLE
Pair of bony tubercles found Anteriorly on
lingual side of body of mandible
 Due to resorption,it may become increasingly
prominent making denture usage difficult

TORUS MANDIBULARIS
Abnormal bony prominence usually found
bilaterally & lingually near the 1st & 2nd
premolar midway b/w soft tissues of the
floor of mouth & crest of alveolar ridge .
 Covered by extremely thin mucosa which
is easily traumatized.
 surgical removal

REFERENCES

Bolender Z. Prosthodontic treatment for edentulous patients .12thed. Pg232-251.

Winkler S. Essentials of complete denture prosthodontics. 2nded. Pg134-138.

Heartwell CM. Textbook of Complete Dentures. 5th ed.Pg-221- 247.

Jacobson T.E , Krol A.J . A Contemporary view of the factors involved in
complete dentures. Part II: Stability . J Prosthet Dent 1983;49(3) :165172

Jacobson T.E , Krol A.J . A Contemporary view of the factors involved in
complete dentures. Part III: Support. J Prosthet Dent 1983;49(3): 306313