OCCLUSION BLOCKS

Question 1

occlusion block is composed of :

Answer 1

-trial denture base ( base material which accurately fits cast)

-occlusion rim (arch shaped material occupying space of patients previous dentition

Question 2

uses of occlusion blocks :

Answer 2

1.) record jaw (centric and eccentric) relation
2.) support lip structure
3.) orientation of occlusal plane
4.) providing matrix for arranging teeth
5.) selecting size and position of artificial teeth by aid of midline , highlip line , canine line

Question 3

markings that help in selecting size and position of artificial teeth in occlusion blocks:

Answer 3

1.) midline
2.) high lip line
3.)canine line

Question 4

trial denture base should be minimum thickness that allows for rigidity

Question 5

examples of temporary trial denture bases

Answer 5

-shellec (thin plastic sheet, easily breaks )

-self cure and light cure acrylic resin (self cure can cause allergic reaction with excess monomer and light cure is susceptible to shrinkage )

-vacuum formed vinyl( difficult to trim and requires expensive equipment )

-baseplate wax (liable to deformation )

-swaged tin

Question 6

examples of permanent trial denture bases ?

Answer 6

1.) metallic ( gold alloys and cobalt chromium alloys)

2.) non metallic : heat cured acrylic resin ( no shrinkage )

Question 7

advantages of heat cured resin denture base :

Answer 7

1.) strong and rigid
2.) requires minimum finishing and polishing
3.) minimum dimensional changes during processing

Question 8

disadvantages of heat cured resin denture base:

Answer 8

1.) time consming
2.) warpage due to 2nd processing attached to teeth

Question 9

warpage of heat cured denture base during 2nd processing when attaching to acrylic teeth can be avoided by using ____

Answer 9

self curing acrylic resin

Question 10

advantages of metal bases:

Answer 10

-no warpage , high strength and accuracy , less deformation in function

-hygienic (less tissue changes under base), easily kept clean

-good thermal conductivity

Question 11

disadvantages of metal bases:

Answer 11

expensive
difficult relining (adding new layer)
time consuming

Question 12

uses of trial denture base:

Answer 12

1,) carries occlusion rim where jaw relation will be recorded

2.) carries artificial teeth to help the try in stage

3.) checks the accuracy of the final impression

Question 13

most common material used for occlusal rim:

Answer 13

wax

Question 14

disadvantages of using wax for occlusion rim:

Answer 14

liable to distortion

inaccurate results in patients with heavy biting force

Question 15

material other than wax used for occlusion rim :

Answer 15

modeling plastic / molding compound

Question 16

disadvantages of using modeling compound for occlusion rim :

Answer 16

-takes longer time for trimming and adjustments

-residual pigments can be transferred from compound to final denture (brown)

Question 17

maxillary rim measurments for
-anterior height:
-anterior width:
-posterior height :
-posterior width :

Answer 17

anterior height : 20-22mm
width:6-8mm

posterior height((shorter): 16-18mm
width(wider): 8-10mm

-wax is centralized over crest of ridge
-slightly labial inclination of the labial contour

Question 18

mandibular rim measurements for posterior height :

Answer 18

2/3 way up the retromolar pad , if it was higher or lower then the patent might accidently bite huis tongue or the denture may be displaced

-no labial inclination

Question 19

the vertical relation of the jaw includes:

Answer 19

-resting vertical dimension
-occlusal vertical dimention (under force)
-interocclusal rest space( freeway space)( difference between them) usually 2-4mm

Question 20

horizontal jaw relations of the jaw:

Answer 20

-centric relation ( mandible is at middle of maxilla)

-maxmial inter-cuspal position (occlusion )

-eccentric relation (protrusion , left and right)

Question 21

2 points from which vertical dimension is taken :

Answer 21

-above mouth at tip of nose

• below ,maximum convexity at chin

Question 22

what are some short term variables that may affect resting vertical dimension measurements ?

Answer 22

• head position ( if head is positioned resting on its back then it will increase)

-respiration

stress (muscle contraction causes measurment to be less)

Question 23

long term variables affecting resting vertical dimension measurement

Answer 23

-loss of proprioceptors( nerves in periodontium giving the patient spatial awareness in his mouth )—> measurment decrease

-old age –> measuurment decrease slightly

Question 24

low vertical dimensions will result in :

Answer 24

• cheek and tongue biting (lower arch will end before the 2/3rd mark on retromolar buccal pad

-loss of biting force

• inharmonious facial proportions

-angular cheilitis (caused by pooling of saliva)

-TMJ disorder

Question 25

high vertical dimentions will result in :

Answer 25

-difficulty in swallowing and speaking

-loss of biting power

-clicking of teeth

-inharmonious facial proportions

-seperated lips when face is at rest

-pain under basal seat, ulceration and inflamation under denture base

TMJ is also affected

Question 26

what is meant by centric relation ?

Answer 26

• position at which mandible is most retracted while NOT being under strain, resting in its socket

Question 27

centric relation is maintained by :

Answer 27

ligaments

Question 28

what is centric occlusion ?

Answer 28

relation between upper and lower teeth when jaw is in centric relation ( doesn’t have to be maximum intercuspation as that is mostly not happening when centric occlusion is taking place )