Occlusion 3

Question 1

what are the forces that determine tooth position?

Answer 1

the alignment of the dentition in the arches occurs due to multidirectional forces acting on teeth during and after eruption where as they erupt they are directed into position and opposing forces are in equilibrium

Question 2

what is labial to the teeth and what forces do they provide?

Answer 2

lips and cheeks
light but constantly lingually directed forces

Question 3

what forces does the tongue provide?

Answer 3

provides labially and buccally directed forces to the lingual surfaces of the teeth

Question 4

what is neutral space?

Answer 4

the position where labio-lingual and bucco-lingual forces are in equilibrium

Question 5

what does the proximal contact between adjacent teeth help maintain? What can constant vertical movements and mastication do?

Answer 5

teeth in normal arch alignment
overtime the proximal areas of the teeth wear and this can cause mesial drifting

Question 6

what does occlusal contacts prevent and what could happen if a tooth is lost?

Answer 6

prevent extrusion or supereruption

if a tooth is lost, the distal tooth most likely will move mesially and the unopposed tooth will most likely erupt

Question 7

what is the buccocclusal (B-O) line?

Answer 7

imaginary line extending through all the buccal cusp tips of the mandibular posterior teeth revealing the general arch form

Question 8

what is the linguocclusal (L-O) line?

Answer 8

in the maxillary arch an imaginary line extends through the lingual cusps of the maxillary posterior teeth to reveal the general arch form

Question 9

what is the central fossa (C-F) line?

Answer 9

an imaginary line drawn through the developmental grooves of the maxillary and mandibular posterior teeth

Question 10

which lines of the dental arch align with each other ?

Answer 10

the maxillary lingual occlusal line (L-O) and the mandibular central fossa line in maximum intercuspation

the mandibular buccal occlusal line (B-O) aligns with the maxillary central fossa line in maximum intercuspation

Question 11

what are supporting cusps and which ones are they?

Answer 11

cusps of teeth that contact in and support maximal intercuspal position

they are usually the facial cusps of mandibular posterior teeth and the maxillary palatal cusps

Question 12

what are the non-supporting cusps?

Answer 12

usually overlap the opposing teeth (lack of this overlap causes biting of cheek or tongue)

maxillary buccal cusps and mandibular lingual cusps

Question 13

what is vertical alignment?

Answer 13

the teeth are not positioned straight up and down
the mandibular posterior teeth have a tendency to tip their crowns lingually and their roots laterally

Question 14

what inclination do the maxillary posterior teeth have?

Answer 14

the crown has a slight buccal inclination
the root has a slight mesial inclination

Question 15

from a lateral view what inclination do all the teeth show? what is a possible exception?

Answer 15

slight mesial inclination
maxillary third molars

Question 16

what alignment do the anterior teeth have?

Answer 16

slight labial protrusion and their crowns seem to incline laterally

Question 17

when the jaw is closed what touches together?

Answer 17

the occlusal surfaces of the maxillary teeth touch the occlusal surfaces of the mandibular teeth

Question 18

when does occlusal contact occur? and what areas will the contact be ?

Answer 18

when the centric cusps contact the opposing central fossa line

the cusps typically contact in one or two areas being the central fossa areas or the marginal ridge and embrasure areas

Question 19

what is cusp fossa occlusion?

Answer 19

the stamp cusp of one tooth occludes in a single fossa of a single opponent where the upper stamp cusps fit into all the fossae of the lower teeth while the lower stamp cusps fir into all the upper fossae except the distal ones of bicuspids

Question 20

what is cusp embrasure occlusion?

Answer 20

occlusion between the upper and lower teeth where each tooth occludes with the opposing tooth

Question 21

what are the advantages of cusp-fossa relation?

Answer 21

• forces are directed along the long axis of the tooth
• there is greater stability to entire arch of teeth and less of a tendency towards tooth movement
  -less chance of food impactions between embrasure

Question 22

in normal interarch tooth relationship each tooth occludes with two opposing teeth except ……?

Answer 22

mandibular central incisor
maxillary third molar

(only occlude with one tooth)

Question 23

what is the significance of interarch tooth relationship?

Answer 23

• helps distribute occlusal forces to several teeth
• helps maintain arch integrity even when a tooth is lost

Question 24

what is a crossbite?

Answer 24

if one or more teeth in the mandibular arch are located facial to their maxillary counterparts

Question 25

what is a premature contact area? What teeth does it occur with? What can this effect?

Answer 25

when the jaw closes all teeth should touch at the same time and if one tooth touches more than another it becomes an interference and bears more weight

occurs with both posterior and anterior teeth

causes the haw to deflect before allowing the other teeth to touch which can affect the muscles of mastication, the TMJ and the offending tooth

Question 26

look at slides 30 to 41 for tooth contacts

Answer 26

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