intra oral mandibular landmarks

Intra Oral Landmarks

Supporting Structures

Limiting Structures

( The Mandible )

Supporting Structures

1. Residual Alveolar Ridge

2. External Oblique Ridge

3. Buccal Shelf Area

4. Retromolar Pad

5. Genial Tubricle

6. Torus Mandibularis

7. Intrnal Oblique Ridge

8. Mental Foramen

1) Residual Alveolar Ridge

The portion of Alveolar Process , and it’s soft tissue covering that remains after the teeth Extraction and the alveolar process has disappeared .

Clinical Significance

1. The highest Portion of the ridge is called Crest of the ridge ( 2ry Stress-Bearing Area) .

2. The crest is covered By Fibrous C.T with Keratinized Layer , and bone type isCancellous Bone.

3. Sometimes , the crest of the ridge being sharp ( Knife edge ) so the denture should be relived opposite it .

4. The slopes of the residual ridge Both ( Buccal & Lingual ) have compact Bone , and can contribute to

resist the horizontal forces .

2) External Oblique Ridge

Bony ridge running downward and forward from ramus to reach mental foramen.

Significance

It’s a limiting structure , the lower denture must covered but not extend beyond it To avoid the displacment by Powerful musculature in this Area

3) Buccal Shelf Area

Bony Area extends between the External oblique ridge and the Alveolar Ridge .

Significance

It Is a 1ry Stress - Bearing Area

1. Bone Type Compact Bone.2. Tissue covering the Area Keratinized tissue. 3. Direction of force on it Perpendicular to the

structure.4. The denture at that Area not relieved.

What is the 2ry stress Bearing area of Mand. !?

What about the 1ry stress bearing Area For maxilla !?

4) Retromolar Pad

Pear-shaped Area , Located distal to the lower 3rd molar .

Clinical Significance

1. Shock Absorbent.

2. Determined the Level of the Occlusal plane must not be higher than its vertical height.

3. Must be covered by denture To Avoid its move backward.

4. Give Retention not support.

5) Genial Tubercle Two bony projections(one

superior and one inferior)at the posterior surface of symphesismenti on the medial surface of mandible.

Muscles attached:-Genioglossusmuscle to superior genial tubercle and geniohyoid muscle to inferior genial tubercle .

clinical significance On bone resorption genial tubercles become close to residual ridge , so they should be relieved .

6) Torus mandibularis

bony projection either unilateral or bilateral at premolar region (between lower4 and lower5) on the medial surface of mandible.

clinical significance

1. if small and not prominent should be relieved

2. if prominent and bulge should be surgically removed

7) mylohyoid line(internal oblique ridge)

start below third molar and extend forward and downward to incisor region below genial tubercles.

Muscles attached: mylohyoidMuscle attached to whole lenght and superior constrictor to posterior end.

clinical significanceshould be covered by denture if sharp should be surgically removed.

8) mental foramen

located on lateral surface of mandible between roots of lower premolars .

mental nerves and vessels pass through it .

clinical significance should be relieved because if it not relieved this cause numbness of lower lip

Limiting Structures1. Buccal Frenum

2. Buccal Vestibule

3. Labial Frenum

4. Labial Vestibule

5. Lingual Frenum

6. Lingual Vestibule

7. Sublingual Glands

8. Lingual Pouch

9. Platoglossal Arch

10.Masseter muscle influencing area

1) Buccal frenum

Thin band of tissue extends from alveolar ridge to cheecks

Form support to cheecks

Clinical SignificanceMust be reliefed by formation of (V) notch on the buccal flange of the denture to avoid ulceration and bad retention of the denture

2) Buccal vestibule

It is the mucous membrane reflection that extends from buccalfrenum posteriorly to the outside back corner of the retromolar pad.

The size of buccal vestibule varies with :1. The contraction of buccinator muscle2. The amount of bone lost from the

mandible

Clinical significance

1. It houses the buccal flang of the mandibulardenture

2. it determines the length of the flang of the denture.

3. When it properly filled with the denture flang,It is greatly enhances the stability and the retention.

3) labial frenum

It is a Fibrous band Covered by mucous memberane that helps to attached the orbicularisoris ( Muscle of the Lip ) to the Labial aspect of the alveolar Ridge.

Clinical SignificanceMust be reliefed by formation of (V) notch on the labial flange of the denture to avoid ulceration and bad retention of the denture

4) labial vestibule

It extends between labial and buccal frenum.

it is divided into right and left by the labial frenum.

Clinical significance

1. IT houses the mandibular labial flang

2. the orbicularis oris muscle has a direct effect on the labial vestibule because its fibers run in horizontal direction with the labial vestibule so , the Labial flang is limited in the extensions and the thickness by the fibers of orbicularis oris muscle and also by incisivuslabi muscle.

5) Lingual Frenum

The thin Fibrous strip of tissue that runs vertically from the floor of the mouth to the undersurface of the tongue

It tends to limit the movement of the tongue

in some people, it is so short that it actually interferes with speaking.

Ankyloglossia , also known as tongue-tie, is a congenital anomaly characterised by an abnormally short lingual frenulum when severe, the tip of the tongue cannot be protruded beyond the lower incisor teeth

Clinical Significance

A notch should be provided in the lingual Flange To avoid displacement of the Lower Denture .

6) the lingual vestibule

it extends from lingual side of the retromolar pad to the lingual frenum

It is divided into :

1. Anterior vestibule (also called sublingual crescent area)

2. Middle vestibule (also called mylohyoid vestibule)

3. Distolingual vestibule (also called retromylohyoidfossa )

Clinical Significance It houses the lingual flang of the denture.

7)Sublingual salivary glands

They lie anterior to the submandibular gland inferior to the tongue.

beneaththemucous membrane of the floor of the mouth.

They are palpated on the floor of the mouth posterior to each mandibular canine.

Clinical Significance

The Forward part of the lingual Flange Area Should be shallow to accommodate the sublingual Salivary gland and to Avoid the irritation of the mucous membrane , which is the least keratinized and the most sensetive.

8) lingual pouch

It is the area pounded:

1. Posteriorly by : the palate glossus arch muscle.

2. Anteriorly by : the mylohyoid muscle.

3. Medially by :the tongue.

4. Laterally by : the medial aspect of the mandible.

Clinical significance

1.The distal extensions of the lingual flang lies in the lingual pouch

2.The flang extends downward covering the mylohyoid ridge to fill the alveolingual sulcus.

9) Masseter muscle influencing area

It is located in the distobuccal corner of the mandible.

Clinical significancsThe posterior extension of inferior buccal part of the denture space is determined by the action of massetermuscle. so,Thedistobuccal corner of the mandibular denture should be converge rapidly to avoid displacement due to the contraction pressure of the masseter muscle.

10)The palatoglossal arch(glossopalatine arch, anterior pillar of fauces)

on either side runs downward, lateral(to the side), and forward to the side of the base of the tongue

it is formed by the projection of the glossopalatine muscle with its coveringmucous membrane

the border between the mouth and the pharynx.

Clinical Significance

The posterior border of the denture must not pass this arch as it will lead to tonsillitis , inflammation in fauces and sore throat by pressure on this muscle

Before & After …

Made By …

Hesham Sayed

Ahmed Mohsen

Mohamed Essam

Mohamed Abo Ghadier

Mohamed fawzy