This document summarizes important anatomic landmarks of the mandible relevant for denture impressions and prosthetics. It describes landmarks like the labial frenum, buccal frenum, lingual frenum, buccal shelf, retromolar pad, and mylohyoid muscle. The document explains how these structures limit denture borders and notes the clinical significance of properly recording landmarks during impressions. It also outlines supporting structures like the buccal shelf and relief areas like the mental foramen that must be accommodated in a well-fitting mandibular denture.

1. Anatomic Landmarks of Mandible
Presented by
Dr.Khushbu Samani
1st year PG
Department of Prosthodontics,
Crown and Bridge
Presented to:
Dr. Narendra Padiyar
Dr. Pragati Kaurani
Dr. Sudhir Meena
Dr. Devender Pal Singh
Dr. Hemant Sharma
Dr. Ajay Gupta
Dr. Prajakta Barapatre

2. 1. Introduction
2. Mucous membrane
3. Limiting structures
4. Supporting structures
5. Relief areas
6. References
Content

3. Introduction
• Knowledge of the orofacial anatomy is necessary for making
impressions, recording jaw relations, adjusting dentures, etc.
• 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.

4. The mandibular denture poses a great technical challenge for the
dentist and often a significant management challenge for the patient.
1.Mandible is less capable of
resisting occlusal forces
than the maxillae.
2.Presence of tongue and its
individual size, form and
activity complicates the
impression procedure.

5. LANDMARKS IN MOUTH
Labial frenum
Labial vestibule
Buccal frenum
Buccal vestibule
Residual alveolar ridge
Retromolar pad
Pterygomandibular raphae
Retromylohyoid fossa
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 flange
Lingual notch
Buccal flange resting on buccal shelf

6. Mucous Membrane
Based on function
Lining mucosa
● Inner aspects of lip
● Cheeks
● Soft palate
● Floor of mouth
● Ventral aspect of tongue
● Alveolar mucosa
● Vestibule
●Faucial pillars
Masticatory mucosa
● Hard palate
● Gingiva
Specialized mucosa
● Dorsal aspect of
tongue

7. Based on epithelium covering
Keratinized mucosa
● Hard palate, gingiva
● Vermilion border of lip
● Some papillae of tongue
Non keratinized mucosa
● Lining mucosa
● Areas lining dorsal of tongue
●Parts of gingiva

8. Clinical significance
● In denture wearers, the keratinization is reduced
● Stratum corneum of epithelium is thinner- this reduces the resistance of epithelium to trauma.
● Removing the dentures for 6-8 hours everyday can provide rest to the soft tissues.

9. Limiting Structures:
• Labial frenum
• Labial vestibule
• Buccal frenum
• Buccal vestibule
• Lingual frenum
• Alveolingual sulcus
• Retromolar pad
• Pterygomandibular raphe

10. Labial Frenum
• Active frenum
• Influenced by Incisivus and Orbicularis oris muscle

11. Clinical significance
• During impression making, recorded as labial
notch by raising the lip gently-outward, upward
and inward
• The denture should be carefully fitted around to
maintain the seal without causing soreness.
Labial
notch

12. Labial vestibule
• Extension: Runs from the labial frenum to the
buccal frenum between the residual alveolar ridge
and lip
• Mentalis is the active muscle in the region which
originates from mental tubercles and inserts into the
lower lip.

13. Clinical significance
• The muscles of the lower lip pull actively across the denture border
• The borders if made thick will displace due to stretching
of orbicularis oris muscle on the wide opening of mouth
• Hence impressions will be the narrowest in the
anterior labial region

14. Buccal frenum
• Single or more bands
• Separates labial and buccal vestibule
• Muscle attachment:
Depressor Anguli Oris
BUCCAL FRENUM

15. Clinical significance
• Frenum should be recorded as buccal notch by pulling
the cheek up, forward and back.
• Relief for buccal frenum is given in denture to avoid
displacement

16. Buccal vestibule
• Extends from buccal frenum to retromolar pad
• Bounded by the residual alveolar ridge on one side and buccinator
on the other side
• Influenced by buccinator muscle anteriorly and pterygomandibular
raphe posteriorly.

17. • Influenced by buccinator muscle which has its
lower fibers attached to the buccal shelf and
external oblique ridge
• The denture should cover completely the buccal
shelf, despite the fact that it will rest directly on
fibers of buccinator muscle
• Fibers of buccinator muscle run parallel to the base
• Hence its pull when in function is parallel to the
border and not not at right angles
• Thus it is not a dislodging factor.

18. • The buccal flange swings wide into the cheek and is
nearly at right angles to the bitting force.
• The impression is always widest in this region

19. • This space is also influenced by the action of masseter
• When masseter muscle contracts it pushes inward against
the buccinator produces a bulge into the mouth
• Can be recorded only when the masseter contracts-patient
is asked to close his mouth against resistance
• Reproduced as a notch in the denture flange called the
Masseteric notch

20. Distobuccal border
• Distobuccal border, at the end of buccal vestibule,
must converge rapidly to avoid displacement by the
contracting masseter muscle
• Recorded by asking the patient to open wide and the
cheek should be well retracted and moved upward and
inward

21. Distal extension
The distal extension of mandibular denture is limited by:
• Ramus of the mandible
• Buccinator muscle fibers that cross from buccal to the lingual
side as they attach to the Pterygomandibular raphe
• Superior constrictor
• Sharpness of lateral bony boundaries of retromolar fossa
Desirable distal extension: slightly to the lingual of these bony
prominences and includes the pear shaped retromolar pad -
Provides soft tissue border seal

22. Retromolar pad
• Is a triangular soft pad of tissue at the distal end of the lower ridge
• Mucosa- thin, nonkeratinized epithelium, and loose alveolar tissue
• Submucosa- contains glandular tissue, fibers of buccinator and superior
constrictor muscles, pterygomandibular raphe and terminal part of
tendon of temporalis
• Clinical significance:
• Denture base should extend approximately one half to two thirds over
retromolar pad

23. Retromolar pad vs pear shaped pad
● Retromolar pad
● Is posterior to the pear shaped pad
● Mucosa is shiny, soft and not stippled
● Pear shaped pad
● Refers to the area formed by residual scar of
the third molar and the retromolar papilla.
● Mucosa is firm, stippled and has a dull
appearance .

24. Pterygomandibular raphe
• 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 :
1. The superior constrictor is inserted posteromedially
2. Buccinator is inserted anterolaterally

25. Lingual frenum
• Mucous membrane fold seen on elevation of the tongue
• A high lingual frenum is called tongue tie
Clinical significance:
• This anterior portion of the lingual flange is called sub lingual
crescent area
• Enough relief should be provide to avoid displacement with
tongue movements
• Recorded by asking the patient to protrude tongue and move it
side to side
Lingual
frenum
Tongue
tie

26. Lingual border
• Provides less resistance than labial and buccal
borders
• Over extension easily causes dislodgement and
soreness
• Action of mylohyoid muscle is an important factor

27. Mylohyoid muscle
• Forms the floor of the mouth
• Arises from whole length of mylohyoid ridge
• Medially fibers join with the fibers of opposite side
• Posteriorly they join hyoid base
• Muscle lies deep to the sublingual gland and other structures in the anterior region and so does not
affect the border of the denture in this region directly
• Posterior part of the mylohyoid muscle in the region affects the lingual border in swallowing and in
moving the tongue.

28. Clinical significance
• Lingual borders in the mylohyoid areas are formed by contact with mylohyoid muscle in
function
• Lingual flange should slope medially toward the tongue. This sloping helps in three ways:
1. The tongue rests over the flange stabilizing the denture
2. Provides space for raising the floor of the mouth without displacing the denture
3. The peripheral seal is maintained during
function

29. Extension of flange wrt to mylohyoid muscle:
1. Flange below the ridge: directed medially towards tongue and parallel to the muscle - guides
the tongue to rest on it.
2. Flange above the ridge: vertical forces might break the seal, leads to displacement and soreness
3. Flange below the ridge and in the undercut: causes soreness

30. Retromylohyoid fossa
• Lies posterior to the mylohyoid muscle
• The fossa is bounded by retromylohyoid curtain

31. Retromylohyoid curtain relation:
• Posterolateral portion overlies with the superior constrictor
muscle
• Laterally by ramus of mandible and Pterygomandibular
raphe.
• Posteromedial portion covers palatoglossal muscle and
lateral surface of the tongue
• Inferior wall overlies the submandibular gland
Clinical significance:
• Denture border should extend posteriorly to contact the
retromylohyoid curtain when the tip of the tongue is
protruded.
Buccinator
Superior
constrictor

32. Alveolingual sulcus
• Space between the residual ridge and the tongue, extends from the lingual frenum to the
retromylohyoid curtain.
• Part of it is available for lingual flange

33. Anterior region
• Extends from lingual frenum to where the mylohyoid ridge curves above the level of the sulcus.
• A depression- premylohyoid fossa can be palpated
Clinical significance:
• Flange should extend to make contact with the mucous membrane floor of the mouth when the tip
of the tongue touches the upper incisors- it raises the floor of the mouth and establishes the length
of the flange.
Anterior
region

34. Middle region
• Extends from premylohyoid fossa to the distal end of the mylohyoid ridge
• Flange: is shallower
• Slope medially from the body of mandible
• Tongue rests on the flange for stability and peripheral seal
• This region is under the influence of the activity of the mylohyoid muscle.
Middle
region

35. Posterior region
Bounded by:
● Anteriorly- mylohyoid muscle
● Laterally- Pear shaped pad
● Posterolaterally- superior constrictor
● Posteromedially- palatoglossus
● Medially- tongue
• It is no longer influenced by the action of the
mylohyoid muscle
• Flange turns laterally toward the ramus to fill the
retromylohyoid fossa under the influence of tongue
and forms the typical ‘S’ shaped lingual flange.

36. Supporting structures
● Primary stress bearing area
● Areas of edentulous ridge that are at right
angles to occlusal forces
● Do not resorb easily
● Made up of dense cortical bone
● Buccal shelf area
● Secondary stress bearing area
● Areas of edentulous ridge that are greater than
right angles to occlusal forces or are parallel
● Rapid resorption may occur
● Made up spongy cancellous bone
● Crest of residual alveolar ridge

37. Buccal shelf area
• Area between the buccal frenum and the anterior border of masseter
• Is intact cortical plate and tends not to resorb due to stimulation of the attachment of
buccinator muscle.
Boundaries
• Laterally- external oblique ridge
• Medially- slopes of residual ridge
• Anteriorly- buccal frenum
• Posteriorly- retromolar pad

38. Histology
• Mucous membrane loosely attached and less keratinized
• Contains thicker submucosal layer
• Fibers of buccinator muscle found in the submucosa immediately overlying bone

39. Crest of residual ridge
• Mucous membrane of the crest of the residual
ridge when attached securely to the underlying
bone is capable of providing good soft tissue
support for the denture
• Due to resorption, the mandible inclines
outward and becomes progressively wider.The
maxillae resorb upward and inward making it
smaller. This gives the prognathic appearance
in long-term edentulous patients.

40. Relief areas
● Mental foramen
● Genial tubercle
● Torus mandibularis

41. Mental foramen
• Lies b/w 1st and 2nd premolar region labially
• Opening for mental nerves and vessels
• Clinical significance:
• Due to ridge resorption, it may lie close to crest of the ridge
• Denture base may exert pressure on vessels
(If not relieved)
• May produce paresthesia of lower lip

42. 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
Genial
tubercle

43. Torus mandibularis
• Abnormal bony prominence usually found bilaterally and lingually near 1st and 2nd premolar midway
midway b/w soft tissue of the floor of the mouth and crest of alveolar ridge
• Covered by extremely thin mucosa which is easily traumatized
• Clinical significance: it can be difficult to provide relief within the denture for the torus without
breaking the border seal
• Hence usually surgical removal is prescribed

44. References
● Boucher’s prosthodontic treatment for edentulous patients
● Essentials of Complete denture prosthodontics by Sheldon Winkler
● Bernard Levin; complete denture prosthodontics- a manual for clinical procedures
● Syllabus of complete denture by Charles Heartwell
● Orban’s oral histology
● Netter’s head and neck anatomy for dentistry
● Textbook of prosthodontics by Deepak Nallaswamy