By: Dr. Ahmed Rabah

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The knowledge of oral anatomy and physiology will help the

operator and provides enough landmarks to act as positive guide

during denture construction.

This subject can be discussed under:

I. Extra-oral landmarks of prosthetic importance.

II. Intra-oral landmarks of prosthetic importance:

In the maxilla.

In the mandible.

III. Border structures that limit the periphery of the denture:

In the maxilla.

In the mandible.

IV. Anatomy and physiology of the T.M.J.

Landmark Description Significance

Angle’s class II Angle’s calss I Angle’s class III

Inter-pupillary line

1. In the maxilla (supporting structures)

2. In the mandible (supporting structures)

Landmark Description Significance →

→

Complete denture limiting structures

1. Labial frenum

2. Labial vestibule

3. Buccal frenum

4. Buccal vestibule

5. Coronoid bulge

6. Residual alveolar ridge

7. Maxillary tuberosity

8. Hamular notch

9. Posterior palatal seal region

10.Foveae palatinae

11.Median palatine raphe

12.Incisive papilla

13.Rugae area

Landmark Description Significance

1. Maxillary labial frenum

Is a fold of mucous membrane extending from mucosa of the lip and attached near the crest of the ridge.

It produces the maxillary labial notch in the denture border.

2. Maxillary labial vestibule (labial sulcus)

It is the part of the oral vestibule that lies between the maxillary ridge and the lips. It extends from the maxillary labial frenum on both sides of the midline.

It is occupied by the labial flange of the denture. The denture flange in this area is in relation to orbecularis oris and incisivus labii superioris muscles which determine the length and thickness of the labial flange.

3. Buccal frenum It is a fold of mucous membrane that varies in size, number and position. It overlies the canninus muscle

It produces the maxillary buccal notch in the impression or the denture to facilitate functional movement.

4. Buccal mucous membrane reflection area (buccal vestibule)

It is the reflection of mucous membrane from the cheek to the alveolar ridge distal to the buccal frenum. The denture border in this area is in relation to buccinator muscle which limits the height and thickness of the denture border.

It represents the maxillary buccal flange of the denture.

5. Pterygo-maxillary notch (hamular notch)

It is a narrow cleft between the maxillary tuberosity and the peterygoid hamulus and filled with connective tissue.

6. Soft palate - It is the posterior border of the upper denture. - It has two parts (immovable part and movable part). - The area of the posterior palatal seal should be located at the junction between these two parts. It is called “vibrating line” or “Ah line”.

- It determines the posterior extension of the denture. - the posterior palatal seal is responsible for the posterior retention of the denture.

Landmark Description Significance

1. Mandibular labial frenum

Is a fold of mucous membrane (contains no muscles) and extending from mucosa of the lip to the mucosa of the alveolar process at the mid line.

It produces the mandibular labial notch in the denture border.

2. Mandibular labial vestibule (labial sulcus)

It is the reflection of the mucosa of the lower lip to the mucosa of the alveolar process.

It is occupied by the labial flange of the denture. The denture flange in this area is in relation to orbecularis oris and incisivus labii inferioris muscles which determine the length and thickness of the labial flange.

3. Buccal frenum - It is a fold of mucous membrane in the premolar area attaching the lip to the alveolar ridge. - It overlies the triangularis muscle.

It produces the mandibular buccal notch in the impression or the denture to facilitate functional movement.

4. Buccal mucous membrane reflection area (buccal vestibule)

- It is the refelction of the mucosa of the cheek to the mucosa of the alveolar process - It is in relation with the buccinator muscle. The buccal flange should rest on the attachment of the buccinator muscle.

It represents the mandibular buccal flange of the denture.

5. masseter muscle influencing area

It is the disto buccal corner of the mandibular denture which is in relation to the masster muscle

Buccal flange must converge in a medial direction to avoid displacement due to contraction of the masseter muscle

6. Reteromolar pad and anterior border of the ramus

- It is a mass of tissue at the distal end of the ridge containing glands, the pterygomandibular raphe fibers of the buccinator muscle and the temporal tendon.

- The denture must cover it.

7. Lingual frenum It is a fold of mucous membrane extending along the floor of the mouth to the under surface of the tongue in the midline.

It produces a lingual notch in the impression or the denture.

Muscles of Mastication

Temporalis Muscle Origin: Temporal fossa Insertion: Coronoid process and anterior border of ramus Function: 1. Elevates and retracts mandible 2. Clenches teeth

Masseter muscle Origin: Superficial portion: anterior 2/3 of lower border of zygomatic arch Deep portion: medial surface of zygomatic arch Insertion: Lateral surface of ramus, coronoid process, and angle of mandible Function: - Elevates mandible. - Clenches teeth

Medial pterygoid muscle • Origin: Medial surface of lateral pterygoid plate • Insertion: Posterior and lower part of medial surface of ramus, angle of mandible • Function: •Elevates, protrudes and latero-trudes the mandible. •Clenches teeth

Lateral pterygoid muscle • Origin: •Superior head: infratemporal surface of greater wing of sphenoid bone •Inferior head: lateral surface of lateral pterygoid plate • Insertion: Anterior portion of condylar neck and articular disc • Function: •Protrudes and laterotrudes the mandible. Pulls articular disc forward