Static Factors of Occlusion Flashcards
What are the factors and forces that determine tooth position?
- labiolingual alignment
- mesiodistal alignment
- vertical position
What affects tooth position?
- muscles
- genetics
- habits
What is the intra-arch tooth alignment?
the relationship of the teeth to each other within the dental arch
What is the plane of occlusion?
the plane that curves to fit the occlusal surfaces and incisla edges of all the teeth
What are the characteristics of the plane of occlusion?
- not flat
- concave on mandible
- convex on maxilla
- teeth positioned in the arches at varying degrees of inclination
What is the angulation of the anterior mandibular teeth in the sagittal plane?
labially inclined
- 20 degrees
What is the angulation of the premolar mandibular teeth in the sagittal plane?
mesially inclined
- 6 degrees
What is the angulation of the molar mandibular teeth in the sagittal plane?
mesially inclined
- 10-15 degrees
What is the angulation of the anterior maxillary teeth in the sagittal plane?
- labially inclined
- central incisor the greatest
- 28 degrees
What is the angulation of the premolar maxillary teeth in the sagittal plane?
mesially inclined
- 9 degrees
What is the angulation of the molar maxillary teeth in the sagittal plane?
mesially inclined
- 12 degrees
- crowns of maxillary molars are tilted distally and labially
What is the angulation of the anterior mandibular teeth in the frontal plane?
vertical inclination
- 0 degrees
What is the angulation of the premolar mandibular teeth in the frontal plane?
- 1st premolar: labial inclination (9 degrees)
- 2nd premolar: lingual inclination (9 degrees)
What is the angulation of the molar mandibular teeth in the frontal plane?
lingual inclination
- 20 degrees
What is the angulation of the anterior maxillary teeth in the frontal plane?
- incisors: distal inclination (2-6 degrees)
- canines: mesial inclination (17 degrees)
What is the angulation of the premolar maxillary teeth in the frontal plane?
slight buccal inclincation
- 5 degrees
What is the angulation of the molar maxillary teeth in the frontal plane?
buccal inclination
- 20 degrees
What is the curve of spee?
- antero-posterior curvature of the occlusal plane
- concave in mandible
- convex in maxilla
What is the curve of wilson?
- medio-lateral curvature of the occlusal plane
- concave in mandibe
- convex in maxilla
What is this?
curve of spee
What is this?
curve of Wilson
When posterior teeth are occluded they are loaded…
axially
Why are posterior teeth loaded axially?
designed to take heavy loads and support the occlusal vertical dimension
When anterior teeth are occluded they are not loaded through…
their long axis
Why are anterior teeth not loaded through their long axis?
not designed for loading
What is the occlusal table?
the area defined by the cusp tips and the mesial and distal cups ridges/arms
Occlusal table is _______% of the buccolingual width of the tooth
50-60%
What does the occlusal table facilitate?
axial loading
Whcih inclines are inside the buccal and lingual cusp ridges and which inclines are outside?
inner inclines - inside
outer inclines - outside
What is the inter-arch tooth alignment?
the relationship of the teeth in one arch to those in the other arch
Which arch is longer?
maxillary arch is longer
Which arch is wider?
maxillary arch is wider
What is the bucco-occlusal (BO) line?
an imaginary line drawn through the buccal cusp tips of the mandibular teeth
What is the linguo-occlusal (LO) line?
- imaginary line defined by joining the lingual cusp tips of the maxillary teeth
What is the central fossa (CF) line?
- imaginary line that follows the central grooves and fossa of all the posterior teeth
The _______ line of the mandible occludes in the central fossa (CF) line of the maxilla
bucco-occlusal (BO)
The ______ line of the maxilla occludes in the central fossa (CF) line of the mandible
linguo-occlusal (LO)
What is the opposite of the ideal inter-arch relationship?
crossbite
What line of the maxilla does the CF line occlude with in the mandible during crossbite?
(BO) bucco-occlusal
What line of the mandible does the CF line occlude with in the maxilla during crossbite?
LO linguo-occlusal
What angles class is ideal occlusion from an orthodontic perspective?
class I
What is a class I molar relationship?
- MB cups of the maxillary 1st molar is alinged over the buccal groove of the mandibular 1st molar
- MB cups of the mandibular 1st molar occludes in the embrasure area between the maxillary second premolar and first molar
- ML cups of the maxillary 1st molar occludes in the central fossa area of the mandibular first molar
What is a class II molar relationship?
- MB cups of the maxillary 1st molar is situated over the embrasure between the mandibular 2nd premolar and 1st molar
- MB cups of the mandibular 1st molar occludes in the central fossa of the maxillary 1st molar
- DL cusp of the maxillary 1st molar occludes in the central fossa of the mandibular 1st molar
What is a class III molar relationship?
- MB cups of the maxillary 1st molar is situated over the embrasure between the mandibular 1st and 2nd molar
- DB cusp of the mandibular 1st molar occludes in the embrasure between distal marginal ridge of the maxillary 2nd premolar and mesial marginal ridge of the maxillary 1st molar
- ML cusp of the maxillary 1st molar is situated in the mesial pit of the mandibular second molar
What is the vertical overlap in class I?
2-4 mm
What is the horizontal overlap in class I?
2-4 mm
What are the two divisions of the class II anterior teeth?
D1: great vertical overlap, mandibular teeth contact the gingival third of the maxillary anterior teeth (Deep bite)
D2: maxillary incisors are lingually inclined (lateral overlap the centrals labially)
What are the two types of class III tooth relationships?
- end-to-end relationship
- mandibular anterior teeth are so far forward they overlap maxillary anterior teeth
