Occlusion: teeth selection and type of occlusal schemes

Question 1

In edentulous pt, how to you decide ideal face height (OVD)?

Answer 1

RECORD REST FACE HEIGHT

measure lower third

dduct 2-3 mm from face height = OVD

Question 2

What do you use to measure face height for OVD?

Answer 2

willis guage

bottom bar press onto bone not just soft tissue

Question 3

what is the only fixed position for a n edentulous pt?

Answer 3

rest face height

Question 4

3 points on a willis gauge?

Answer 4

the position of the fixed arm under the nose

the position of the sliding arm under the chin

the vertical orientation of the gauge

Question 5

free way space?

Answer 5

you want this

difference between teeth at rest and in RCP (closed)

Question 6

how to record bite?

Answer 6

record blocks

record rims should be placed in well-fitting rigid bases

• heat cured acrylic bases –> permanent denture base
• cold-curing acrylic resin
• shellac (cold cured)

Question 7

try in mandibular or maxillary first?

Answer 7

maxillary

Question 8

what happens if the wax try-in the denture is unretentive?

Answer 8

pt might do altered movements to try keep it in place

Question 9

can you just add on to the flanges to extend them?

Answer 9

no - need new impression

Question 10

where can you add or remove wax from?

Answer 10

lip support

incisal level

incisal tooth position

buccal

palatal surfaces

(latter changes to arch width)

Question 11

Can you remove wax to change occlusal plane orientation?

Answer 11

yes on upper block

fox’s plane guide - should be parallel to ala-tragus line

Question 12

when you are happy with the maxillary wax block, what do you do?

Answer 12

mark:

either side of nose

smile line

filtrum - midline

Question 13

What do you adjust the lower block in relation to?

Answer 13

upper block

Question 14

what to think about when trimming the lower wax block?

Answer 14

lip support, buccal and lingual surfaces

care with position of occlusal surfaces in relation to tongue

correct OVD - 2-4 mm between biting and rest position

Question 15

how much free way space is needed?

Answer 15

2-4 mm

Question 16

how to record the jaw relationship after both bite blocks are fitting well?

Answer 16

cut 2 notches is posterior occlusal surface of upper block –> one on each side

place upper record block in opts mouth

apply appropriate adhesive to lower block for bite recording paste being used

apply sufficient bite recording paste to occlusal surfaces of lower block - NOT ONTO ANTERIORS

insert block and guide pt into correct jaw relationship

allow sufficient time for material to set before removing from mouth - NOT A SNAP SET - hold for around 30 seconds

remove blocks carefully - may be sealed together

separate blocks carefully so that dental technician can cast impressions in upper and lower blocks where required

select appropriate anterior and posterior teeth

prescribe for correct articulator

Question 17

how to know the bite blocks are fitting well?

Answer 17

pt needs to be in supine position

check relationship with blocks in pts mouth

ensure that is is as reproducible as possible

record ligamentous (or retruded contact position) if pt has moved to habitual path of closure

ligamentous position is considered the most reproducible

recheck that there is an identified FWS

ensure centre line is appropriate and marked if removed during modifications

Question 18

what is the shade guide used?

Answer 18

DELPHIC V or VITA

Question 19

what type of occlusal schemes are we going to prescribe? (most common)

Answer 19

most common: conventional bilateral balanced occlusion :

• inter-cuspal position = retruded contact position
• ICP on posterior teeth
• working side and balancing side contacts in lateral excursions
• anterior and posterior contact in protrusive excursions

Question 20

why do we have the conventional bilateral balanced occlusion scheme?

Answer 20

mutually protecting

• denture will not be displaced if something is eaten on one side

contacts when pt has lateral and protrusive movement

Question 21

What is lingualized bilaterally balanced occlusion?

Answer 21

• maxillary palatal cusps contacting mandibular central fossae
• different from conventional bilateral balanced occlusion by eliminating the contact between the mandibular buccal cusps and maxillary central fossae

Question 22

How to achieve lingualized bilaterally balanced occlusion?

Answer 22

1 - modify anatomical mandibular posterior teeth or

2 - by applying anatomical maxillary posterior teeth against flat mandibular posterior teeth

Question 23

What is the monoplane occlusion occlusal scheme?

Answer 23

can be establish balanced or nonbalanced occlusion

occlusal contact comprise surfaces rather than points

Question 24

3 types of occlusal scheme you can prescribe?

Answer 24

conventional bilateral balanced occlusion

lingualized bilaterally balanced occlusion

monoplane occlusion occlusal scheme

Question 25

when to prescribe LBBO?

Answer 25

severely resorbed ridge on mandibular arch

ALLOWS - masticatory efficiency and preservation of ICP)

Question 26

factors influencing teeth selection?

Answer 26

previous dentures (if any)

age of pt

size and shape of facial skeleton

colour of complexion

pt choice

pt friend

OK or Hello magazine

old photos - usually school or wedding

Question 27

materials of teeth?

Answer 27

acrylic

composite

porcelain

combination

Question 28

acrylic teeth pros and cons?

Answer 28

highly cross-linked acrylic (improves wear resistance and colour stability)

good appearance and adhesion to denture base

wears quickly

Question 29

composite teeth pros and cons?

Answer 29

harder and longer lasting than acrylic

good aesthetic properties

reduced bond strength to underlying acrylic

can be modified/added

Question 30

porcelain teeth pros and cons?

Answer 30

retention to denture base through mechanical features celled diatoric holes (pins) designed into teeth (can be dislodged)

good appearance but can be noisy, chip with high occlusal forces, extra weight

Question 31

How to decide central incisor width?

Answer 31

using philtrum width

the height of the central incisor should be equal to or greater than the height if the smile line above the incisal edge

high smile should be marked on the wax rim

Question 32

when to use larger central incisor?

Answer 32

high lip line

larger stature

larger face

Question 33

how to find canine position?

Answer 33

using a straight edge aligned with the inner canthus of the eye and the ala of the nose to find the position of the canine

Question 34

how to select teeth shape?

Answer 34

using pt old denture

inverted shape of pts shape

shape of pt upper plate

Question 35

4 types of teeth shape? `

Answer 35

square : complement square set face and strong features

ovoid : create sifter appearance and complement delicate, rounded features

tapering : tapering face

rectangular : long square shaped faces

Question 36

How does position of teeth change with age and how would you consider this in denture design?

Answer 36

attrition of natural teeth:
incisal edge will tend to be flattened

loss of muscular toe of lips and face:
flanges and teeth need to attempt to restore ‘appearance’ (can be difficult)

need to place anterior teeth in correct position:
lip support but if too far anterior –> denture displacement

amount of tooth showing :
at rest and when smiling

Question 37

positioning of posterior teeth?

Answer 37

Question 38

3 compensating curves when positioning teeth?

Answer 38

anterior posterior- curve of spee

laterally- curve of monson

mediolaterl curve- curve of wilson

Question 39

anterior posterior curve?

Answer 39

curve of spee

Question 40

lateral curve?

Answer 40

curve of monson

Question 41

mediolateral curve?

Answer 41

curve of wilson