Occlusion 3 Flashcards
what are the forces that determine tooth position?
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
what is labial to the teeth and what forces do they provide?
lips and cheeks
light but constantly lingually directed forces
what forces does the tongue provide?
provides labially and buccally directed forces to the lingual surfaces of the teeth
what is neutral space?
the position where labio-lingual and bucco-lingual forces are in equilibrium
what does the proximal contact between adjacent teeth help maintain? What can constant vertical movements and mastication do?
teeth in normal arch alignment
overtime the proximal areas of the teeth wear and this can cause mesial drifting
what does occlusal contacts prevent and what could happen if a tooth is lost?
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
what is the buccocclusal (B-O) line?
imaginary line extending through all the buccal cusp tips of the mandibular posterior teeth revealing the general arch form
what is the linguocclusal (L-O) line?
in the maxillary arch an imaginary line extends through the lingual cusps of the maxillary posterior teeth to reveal the general arch form
what is the central fossa (C-F) line?
an imaginary line drawn through the developmental grooves of the maxillary and mandibular posterior teeth
which lines of the dental arch align with each other ?
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
what are supporting cusps and which ones are they?
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
what are the non-supporting cusps?
usually overlap the opposing teeth (lack of this overlap causes biting of cheek or tongue)
maxillary buccal cusps and mandibular lingual cusps
what is vertical alignment?
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
what inclination do the maxillary posterior teeth have?
the crown has a slight buccal inclination
the root has a slight mesial inclination
from a lateral view what inclination do all the teeth show? what is a possible exception?
slight mesial inclination
maxillary third molars
what alignment do the anterior teeth have?
slight labial protrusion and their crowns seem to incline laterally
when the jaw is closed what touches together?
the occlusal surfaces of the maxillary teeth touch the occlusal surfaces of the mandibular teeth
when does occlusal contact occur? and what areas will the contact be ?
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
what is cusp fossa occlusion?
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
what is cusp embrasure occlusion?
occlusion between the upper and lower teeth where each tooth occludes with the opposing tooth
what are the advantages of cusp-fossa relation?
- 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
in normal interarch tooth relationship each tooth occludes with two opposing teeth except ……?
mandibular central incisor
maxillary third molar
(only occlude with one tooth)
what is the significance of interarch tooth relationship?
- helps distribute occlusal forces to several teeth
- helps maintain arch integrity even when a tooth is lost
what is a crossbite?
if one or more teeth in the mandibular arch are located facial to their maxillary counterparts
what is a premature contact area? What teeth does it occur with? What can this effect?
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
look at slides 30 to 41 for tooth contacts
**
