Selection of artificial teeth Flashcards
how can we determine the width of maxillary anterior teeth?
- 1/3 bizygomatic width using facebow
- from one canine eminence to the other
- from corner of the mouth to the other
How many mm of the teeth must be shown at rest?
2mm of the tip
How many mm of teeth is shown when the lips are short?
5mm
How many mm of teeth is shown when the lips are long?
flushing of lip on teeth takes place
As length of lip increases, how much of the tooth is shown?
decrease tooth shown
What is the shape of the teeth related to?
shape of the face = shape of the arch = shape of the teeth
What teeth are selected for tapered faces?
tapered face = tapered arch = tapered teeth
What teeth are selected for square faces?
square face = square arch = square teeth
What teeth are selected for ovoid faces?
ovoid face = ovoid arch = ovoid teeth
What should the labial surface of the tooth be in harmony with?
facial profile
What labial surface should be used if facial profile is flat?
flat labial surface
What labial surface should be used if facial profile is curved?
curved labial surface
What is the facial features of females and what are the anterior teeth selected according to that?
- facial features are curved
- tapered or ovoid anterior teeth are used
What is the facial features of males and what are the anterior teeth selected according to that?
- facial features are square
- square anterior teeth should be used
What does the selection of a suitable shade for maxillary anterior teeth depends on?
- patient’s age
- colour of the patient’s eyes and hair
- patient’s general complexion
- patient’s personal approval
What is the most important factor when deciding on a suitable shade for maxillary anterior teeth?
patient’s approval
What happens to the shade (colour) of teeth as people age?
teeth get darker
What is the size of posterior artificial teeth compared to posterior natural teeth
artificial posterior teeth are 40% less than size of natural posterior teeth
Why are artificial posterior teeth have a smaller size than natural posterior teeth?
- increases sharpness of teeth
- increases cutting efficiency
- reduces forces applied
What are upper posterior teeth parallel to?
ala-tragus line (camper’s line)
What happens if lower posterior teeth are arranged buccal to the crest of the ridge?
- tooth is directly above denture base
- when patient eats, it causes denture instability
What should the upper anteroposterior dimension be?
8-10mm anterior (infront) of incisive papilla
Where should the lower posterior teeth be arranged?
on the crest of the ridge
What happens if lower posterior teeth are arranged lingual to the crest of the ridge?
- cramped tongue
- rocking and instability of denture
What are the causes of cramped tongue?
- teeth are arranged lingually in relation to the crest of the ridge
- teeth arranged above lateral border of the tongue
What is the anteroposterior dimension of posterior lower teeth?
teeth arrangement is from canine to befre retromolar pad
What happens if teeth are arranged at the retromolar pad?
- retromolar pad is inclined
- teeth will be inclined
- forces are lateral
- instability of denture
What is the shape of the lower teeth?
same as upper
What happens if upper teeth are arranged on the crest of the ridge?
collapsing of patient’s mouth
Why should the lateral borders of the tongue be higher than lower occlusal plane?
- avoid cramped tongue
- maintain normal masticatory cycle
- in coordination of buccinator muscles
- stability of lower denture
What are the causes of cheek biting?
- low VDO
- lower posterior teeth arranged lateral to crest of the ridge
What are the forms of posterior teeth?
- anatomic form
- modified anatomic form
- non-anatomic form or monoplane
What is anatomic form?
- cusp angles are 33 degrees
- not used for complete dentures as it is very steep
- increases lateral forces
What is modified anatomic form?
- less cusp angles than anatomic form
- 20 degrees
- most commonly used for complete dentures
- high lateral forces
What is non-anatomic form?
- flat occlusal surfaces
- used in complete dentures sometimes
- decreased lateral forces
- not aesthetic
- blunt (more chewing)
What are the conditions that require non-anatomic form?
- 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)
What are the characteristics of acrylic teeth?
- 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
What are the characteristics of porcelain teeth?
- 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
Why is it very recommended to use acrylic teeth?
acts as shock absorber
