Lecture 2: Anatomy & Final Impression

Question 1

List the extra oral landmarks

Answer 1

1. Inter pupillary line 2. Ala-Tragus line (Camper’s Line) 3. Canthus-Tragus line 4. Vermillion Border 5. Philtrum 6. Naso-labial sulcus 7. Naso-labial angle 8. Mento-labial sulcus 9. Modiolus

Question 2

What is the inter pupillary line?

Answer 2

a. Extra-oral landmark b. Imaginary line running between the two pupils of the eye when the patient is looking straight forward c. Prosthetic significance: anterior occlusal plane of the denture’s teeth should be parallel to inter-pupillary line

Question 3

What is the Ala-Tragus line (Camper’s line)?

Answer 3

a. Extra-oral landmark b. Imaginary line running from the inferior border of the Ala of the nose to the superior border of the Tragus of the ear. c. Prosthetic significance: posterior occlusal plane of the denture’s teeth should be parallel to the Ala-Tragus line

Question 4

What is the Canthus-Tragus line?

Answer 4

a. Extra-oral landmark b. Imaginary line running from the outer canthus of the eye to the superior border of the tragus of the ear. c. Prosthetic significance: the position of the Condyl’s hinge axis is 11-13 mm from the Tragus of the ear on this line.

Question 5

What is the vermillion border?

Answer 5

a. Extra-oral landmark b. Transitional epithelium between the mucous membrane of the lip and the skin c. Prosthetic significance: - After extraction it becomes thinner in the upper lip - Complete denture construction will provide labial support with restoration of esthetics

Question 6

What is the philtrum?

Answer 6

a. Extra-oral landmark b. Diamond-shaped area between the center of the upper lip and the base of the nose. c. Prosthetic significance: after extraction of teeth it becomes flattened and can be restored by a complete denture

Question 7

What is the nasio-labial sulcus?

Answer 7

a. Extra-oral landmark b. Depression that extends from the ala of the nose in a downward and lateral direction to the corner of the mouth. c. Prosthetic significance: after extraction of teeth it becomes accentuated and can be restored by complete denture

Question 8

What is the nasio-labial angle?

Answer 8

a. Extra-oral landmark b. Angle between the Columella of the Nose and the Philtrum of lip. Normally is 90 degrees when viewed from the profile. c. Prosthetic significance: After extraction of teeth it becomes more obtuse and can be restored by a complete denture.

Question 9

What is the mento-labial sulcus?

Answer 9

a. Extra-oral landmark b. Horizontal depression that runs between the lower lip and chin. c. Prosthetic significance: Classification: 1 - Angle class [I]: Normal ridge relationship. 2 - Angle class [II]: Retruded mandibular position 3 - Angle class [III]: Protruded maxillo-mandibular relationship

Question 10

What is modiolus?

Answer 10

a. Extra-oral landmark b. Intersection point of the facial expression muscles. Is situated laterally and slightly superiorly to the corner of the mouth. c. Prosthetic significance: - Sunken cheeks appearance and dropped angle observed by loss of maxillary teeth and can be restored by the maxillary complete denture. - Very forceful area which can influence the labial flange thickness of the maxillary

Question 11

What are the two groups of intra-oral structures?

Answer 11

a. Supporting structures b. Limiting structures

Question 12

Define retention.

Answer 12

Resistance to the dislodging forces along the path of placement.

Question 13

Define stability.

Answer 13

Resistance to displacement by functional horizontal or rotational stresses.

Question 14

Define support.

Answer 14

Resistance to the tissue-word forces and provided by the foundation area on which the denture rest.

Question 15

Define primary stress bearing area.

Answer 15

a. Intra-oral structure b. Area under the denture which can withstand stresses and resist tissue words movement. These area should have the following characters: 1) Covered by keratinized mucosa 2) Supported by a compact bone (no change) 3) Horizontal to the masticatory force with no lateral force formation (increase support stability)

Question 16

What are the primary stress bearing area for the maxilla and mandible?

Answer 16

Maxilla: Horizontal part of the hard palate, well formed residual ridge Mandible: Buccal shelf of bone and retro-molar pad area

Question 17

Define secondary stress bearing area.

Answer 17

a. Intra-oral structure b. Area that can withstand stresses, but don’t have all 3 characters of the primary stress bearing area.

Question 18

What are the secondary stress bearing area for the maxilla and mandible?

Answer 18

Maxilla: palatine rugae area (inclined part of the hard palate) Mandible: residual ridge

Question 19

Define relief area.

Answer 19

a. Intra-oral structure b. Any area that causes pain or instability upon pressure on it, these area should be relieved.

Question 20

What are the relief areas for the maxilla and mandible?

Answer 20

Maxilla: median palatine raphe (rocking & pain), incisive papilla (pain) Mandible: knife edge residual ridge, mental foramen, genial tubercles and mylohyoid ridge

Question 21

What is the maxillary residual ridge?

Answer 21

a. Intra-oral structure (maxilla) b. Portion of the alveolar process and its soft tissue coverage that remains after extraction, the highest continuous surface of the ridge is called Crest of the ridge c. Prosthetic significance: primary stress bearing area

Question 22

What are the shapes that the maxillary ridge and palate form?

Answer 22

a. Intra-oral structure. b. “U” shape c. “V” shape d. Flat e. Rounded

Question 23

What is the maxillary tuberosity?

Answer 23

a. Intra-oral structure (maxilla) b. Prominent bulge located just behind the distal end of the maxillary ridge c. Prosthetic significance: 1) well formed tuberosities provide wide coverage with enhancement of support, stability, and retention (primary stress bearing area) 2) large maxillary tuberosity i. relieved over the undercut ii. modify the path of insertion (unilateral enlargement) iii. surgical excision of extremely large tuberosity which interfere with the denture base space

Question 24

What is the incisive papilla?

Answer 24

a. Intra-oral landmark (maxilla) b. Pear-shaped elevation present in the midline behind the 2 central incisors c. Prosthetic significance: 1) landmark for setting of teeth (8-10 mm lingual to the maxillary central incisors) 2) after extraction of teeth it migrates to the crest of the ridge 3) Should be relieved to avoid the burning sensation of the palate (nasopalatine nerve)

Question 25

What is the median palatine raphe?

Answer 25

a. Intra-oral structure (maxilla) b. Mucoperiostium that covers the median palatine suture c. Prosthetic significance: When it is prominent it should be relieved. Lack of relief can cause: 1 - rocking of the denture 2 - tissue ulceration 3 - mid-line denture fracture

Question 26

What is the palatine rougae?

Answer 26

a. Intra-oral structure (maxilla) b. Irregular elevations radiates from the midline of the anterior part of the palate c. Prosthetic significance: - secondary stress bearing area - prevent forward movement of the denture - if it is sensitive or prominent it should be relieved

Question 27

What is the torus palatinus?

Answer 27

a. Intra-oral structure (maxilla) b. Bony prominence usually present at both sides of the midline of the palate c. Prosthetic significance: - It should be: 1 - relieved 2 - surgical removal

Question 28

What is the fovea palatinae?

Answer 28

a. Intra-oral structure (maxilla) b. Two openings of minor salivary glands present in both sides of the midline posterior to junction of hard and soft palate c. Prosthetic significance: determines the posterior extension of the upper denture (2mm posterior to fovea palatinae)

Question 29

What is the horizontal part of the palate?

Answer 29

a. Intra-oral structure (maxilla) b. Made of compact bone and covered by dense keratinized mucosa c. Prosthetic significance: considered one of the primary stress bearing area

Question 30

What is the mandibular residual ridge?

Answer 30

a. Intra-oral structure (mandible) b. Portion of the alveolar process with it’s soft tissue covering the remains after extraction c. Prosthetic significance: 1) Not used as a primary stress bearing area –> covered by movable fibrous connective tissue 2) Doesn’t provide stability or support

Question 31

What muscles intersect at the modiolus?

Answer 31

1. Buccinators* 2. Orbicularis oris* 3. Platysma* 4. Risorius 5. Zygomaticus major* 6. Levator labii superioris 7. Levator anguli oris 8. Depressor anguli oris

Question 32

What is the external oblique ridge?

Answer 32

a. Intra-oral structure (mandible) b. Bony ridge running downward and forward from the Ramus to reach Mental foramen c. Prosthetic significance: complete denture can’t extend over it

Question 33

What is the buccal shelf of bone?

Answer 33

a. Intra-oral structure (mandible) b. Bordered externally by the external oblique line and internally by the slope of the residual ridge. c. Prosthetic significance: primary stress bearing area

Question 34

What is the mental foramen?

Answer 34

a. Intra-oral structure (mandible) b. Located on the buccal surface of the mandible between the roots of 1st and 2nd premolars c. Prosthetic significance: In cases of severe residual ridge resorption, the foramen occupies a more superior position and the denture base must be relieved to prevent nerve compression, numbness, or pain.

Question 35

What is the retromolar pad?

Answer 35

a. Intra-oral structure (mandible) b. Pear-shaped area located distal to the lower 3rd molar c. Prosthetic significance: - Primary stress bearing area - It contains: 1) glandular tissue 2) fibers of pterygomandibular raphe 3) fibers of the buccinator 4) fibers of superior constrictor 5) fibers of the temporal tendon - Made of compact bone - Constant, relatively unchanging structure, used as a landmark to determine the level of the occlusal plane (1/2 to 2/3 of it’s height)

Question 36

What is the torus mandibularis?

Answer 36

a. Intra-oral structure (mandible) b. Bony prominence located at the inner surface of premolar area (unilateral or bilateral) c. Prosthetic significance: - It should be: 1 - Relieved 2 - Surgical removal

Question 37

What is the internal oblique ridge?

Answer 37

a. Intra-oral structure (mandible) b. Irregular bony ridge on the inner surface of the mandible where the mylohyoid muscle attach; it influences the length of the lingual flange. c. Prosthodontic significance: If it is prominent or sharp, relief will be required.

Question 38

What is the genial tubercles?

Answer 38

a. Intra-oral structure (mandible) b. Two bony projections present at the inner surface of mandible at midline on each side of symphesis. c. Prosthodontic significance: - Represent the attachment of geniohyoid and genioglossus muscles. - In severe resorption the genial tubercles will be even higher than the ridge, it should be relieved.

Question 39

Define what an intra-oral limiting structure is.

Answer 39

Border structures that limit the denture periphery.