Selection of artificial teeth

Question 1

how can we determine the width of maxillary anterior teeth?

Answer 1

• 1/3 bizygomatic width using facebow
• from one canine eminence to the other
• from corner of the mouth to the other

Question 2

How many mm of the teeth must be shown at rest?

Answer 2

2mm of the tip

Question 3

How many mm of teeth is shown when the lips are short?

Answer 3

5mm

Question 4

How many mm of teeth is shown when the lips are long?

Answer 4

flushing of lip on teeth takes place

Question 5

As length of lip increases, how much of the tooth is shown?

Answer 5

decrease tooth shown

Question 6

What is the shape of the teeth related to?

Answer 6

shape of the face = shape of the arch = shape of the teeth

Question 7

What teeth are selected for tapered faces?

Answer 7

tapered face = tapered arch = tapered teeth

Question 8

What teeth are selected for square faces?

Answer 8

square face = square arch = square teeth

Question 9

What teeth are selected for ovoid faces?

Answer 9

ovoid face = ovoid arch = ovoid teeth

Question 10

What should the labial surface of the tooth be in harmony with?

Answer 10

facial profile

Question 11

What labial surface should be used if facial profile is flat?

Answer 11

flat labial surface

Question 12

What labial surface should be used if facial profile is curved?

Answer 12

curved labial surface

Question 13

What is the facial features of females and what are the anterior teeth selected according to that?

Answer 13

• facial features are curved
• tapered or ovoid anterior teeth are used

Question 14

What is the facial features of males and what are the anterior teeth selected according to that?

Answer 14

• facial features are square
• square anterior teeth should be used

Question 15

What does the selection of a suitable shade for maxillary anterior teeth depends on?

Answer 15

• patient’s age
• colour of the patient’s eyes and hair
• patient’s general complexion
• patient’s personal approval

Question 16

What is the most important factor when deciding on a suitable shade for maxillary anterior teeth?

Answer 16

patient’s approval

Question 17

What happens to the shade (colour) of teeth as people age?

Answer 17

teeth get darker

Question 18

What is the size of posterior artificial teeth compared to posterior natural teeth

Answer 18

artificial posterior teeth are 40% less than size of natural posterior teeth

Question 19

Why are artificial posterior teeth have a smaller size than natural posterior teeth?

Answer 19

• increases sharpness of teeth
• increases cutting efficiency
• reduces forces applied

Question 20

What are upper posterior teeth parallel to?

Answer 20

ala-tragus line (camper’s line)

Question 21

What happens if lower posterior teeth are arranged buccal to the crest of the ridge?

Answer 21

• tooth is directly above denture base
• when patient eats, it causes denture instability

Question 22

What should the upper anteroposterior dimension be?

Answer 22

8-10mm anterior (infront) of incisive papilla

Question 23

Where should the lower posterior teeth be arranged?

Answer 23

on the crest of the ridge

Question 24

What happens if lower posterior teeth are arranged lingual to the crest of the ridge?

Answer 24

• cramped tongue
• rocking and instability of denture

Question 25

What are the causes of cramped tongue?

Answer 25

- teeth are arranged lingually in relation to the crest of the ridge - teeth arranged above lateral border of the tongue

Question 26

What is the anteroposterior dimension of posterior lower teeth?

Answer 26

teeth arrangement is from canine to befre retromolar pad

Question 27

What happens if teeth are arranged at the retromolar pad?

Answer 27

- retromolar pad is inclined - teeth will be inclined - forces are lateral - instability of denture

Question 28

What is the shape of the lower teeth?

Answer 28

same as upper

Question 29

What happens if upper teeth are arranged on the crest of the ridge?

Answer 29

collapsing of patient's mouth

Question 30

Why should the lateral borders of the tongue be higher than lower occlusal plane?

Answer 30

- avoid cramped tongue - maintain normal masticatory cycle - in coordination of buccinator muscles - stability of lower denture

Question 31

What are the causes of cheek biting?

Answer 31

- low VDO - lower posterior teeth arranged lateral to crest of the ridge

Question 32

What are the forms of posterior teeth?

Answer 32

- anatomic form - modified anatomic form - non-anatomic form or monoplane

Question 33

What is anatomic form?

Answer 33

- cusp angles are 33 degrees - not used for complete dentures as it is very steep - increases lateral forces

Question 34

What is modified anatomic form?

Answer 34

- less cusp angles than anatomic form - 20 degrees - most commonly used for complete dentures - high lateral forces

Question 35

What is non-anatomic form?

Answer 35

- flat occlusal surfaces - used in complete dentures sometimes - decreased lateral forces - not aesthetic - blunt (more chewing)

Question 36

What are the conditions that require non-anatomic form?

Answer 36

- cross bite ridge relationship (class 2 and 3) - cases suffering from TMJ disturbances - cases with advances ridge resorption (flat ridge and short flanges are used so teeth move easily)

Question 37

What are the characteristics of acrylic teeth?

Answer 37

- composition: polymethyl methacrylate - specific gravity is low - resistance to wear and abrasion is low - easy/ /to adjust - resilient - no clicking sound - harmless effect on underlying tissue - used for flat and flabby ridges - chemical union with denture base - affected with direct heat - crazing by organic solvents - aesthetics is less agreeable than porcelain

Question 38

What are the characteristics of porcelain teeth?

Answer 38

- composition: porcelain material - high specific gravity - resist wear and abrasion (preserve V.D.O.) - difficult to adjust - brittle - harmful effect on underlying tissues - used inn well developed ridges - mechanical union with denture base - not affected with direct heat - resist action of organic solvent - aesthetic is more agreeable than acrylic

Question 39

Why is it very recommended to use acrylic teeth?

Answer 39

acts as shock absorber