3/6: Static Factors of Occlusion Flashcards
What are static factors of occlusion?
Characteristics shared by the teeth when they are stationary
What are factors and forces that determine the tooth position?
- labiolingual alignment
- mesiodistal alignment
- vertical position
What things are components of tooth position?
Muscles
- cheeks, lips, and tongue
- neutral zone
Genetic
- size and shape of arch and teeth -> available space
Habits
Interproximal Contacts
Occlusal contacts
What are interproximal contacts?
Maintain tooth position
What is mesial drift?
Alveolar bone and gingival fibers
What do occlusal contacts do?
Maintain tooth position
What is intra-arch tooth alignment?
The relationship of the teeth to each other within the dental arch
What is the ‘plane’ of occlusion?
‘Plane’ that curves to fit the occlusal surfaces and incisal edges of all the teeth
Describe the plane of occlusion
- it is not flat
- teeth positioned in the arches at varying degrees of inclination
Is the mandible concave or convex?
Concave
Is the maxilla concave or convex?
Convex
What is angulation of the teeth determined by?
The long axis of the tooth (crown and root)
What is the angulation of the mandibular anterior teeth?
Labially inclined (20 degrees)
What is the angulation of the mandibular premolars?
Mesially inclined (6 degrees)
What is the angulation of the mandibular molars?
Mesially inclined (10-15 degrees)
What is the angulation of the maxillary anterior teeth?
Labially inclined - central incisor greates (28 degrees)
What is the angulation of the maxillary premolar?
Mesially inclined (9 degrees)
What is the angulation of the maxillary molars?
Mesially inclined (12 degrees)
Crowns of the maxillary molars are tilted distally (and labially)
What is the angulation of the mandibular anterior teeth in the frontal plane?
Vertical inclination (0 degrees)
What is the angulation of the mandibular premolars in the frontal plane?
1st premolar - labial inclination (9 degrees)
2nd premolar - lingual inclination (9 degrees)
What is the angulation of the mandibular molars in the frontal plane?
Lingual inclination (20 degrees)
What is the angulation of the maxillary anterior teeth in the frontal plane?
Incisors - distal inclination (2-6 degrees)
Canines - mesial inclination (17 degrees)
What is the angulation of the mandibular premolars in the frontal plane?
Slight buccal inclination (5 degrees)
What is the angulation of the mandibular molars in the frontal plane?
Buccal inclination (20 degrees)
What is the curve of spee?
Antero-posterior curvature of the occlusal plane
Where is the curve of spee concave and convex?
Concave in mandible, convex in maxilla
What is the curve of wilson?
Medio-lateral curvature of the occlusal plane
Where is the curve of wilson concave and convex?
Concave in the mandible, convex in the maxilla
Where are posterior teeth loaded when they occlude?
Axially
What are posterior teeth designed to take?
Heavy loads, support the occlusal vertical dimension
When anterior teeth occlude, where are they not loaded?
Through their long axis
What are anterior teeth not designed for?
Loading
What is the occlusal table?
The area defined by the cusp tips and the mesial and distal cusp ridges/arms
How much of the width of the tooth is the occlusal table?
50-60% of the buccolingual width of the tooth
What does the occlusal table facilitate?
Axial loading
What is the inner incline of the occlusal table?
Incline inside the buccal and lingual cusp ridges
What is the outer incline of the occlusal table?
Inclines outside the buccal and lingual cusp ridges
What is inter-arch alignment?
The relationship of the teeth in one arch to those in the other arch
What are the types of arch shapes?
U shaped/square/tapering
Symmetricl, smooth in outline
Which arch is wider?
Maxilalry
Which arch is longer?
Maxillary
Max: 128mm long
Mand: 126mm long
What do the buccal cusps of the mandibular posterior teeth and the lingual cusps of maxillary posterior teeth occlude?
With opposing central fossa areas
- to minimize trauma to soft tissue
What are supporting/centric/functional/stamp cusps?
Lingual cusps of maxillary teeth and buccal cusps of mandibular teeth
What are guiding/non-centric/balancing/shearing cusps?
Buccal cusps of maxillary teeth and lingual cusps of mandibular teeth
What is the bucco-occlusal line?
Imaginary line drawn through the buccal cusp tips of the mandibular teeth
What is the linguo-occlusal line?
Imaginary line defined by joining the lingual cusp tips of the maxillary teeth
What is the central fossa line?
Imaginary line that follows the central grooves and fossa of all the posterior teeth
What does the bucco-occlusal line of the mandible occlude?
In the central fossa (CF) line of the maxilla
What does the linguo-occlusal line of the mandible occlude?
In the central fossa (CF) line of the mandible
What is crossbite?
The opposite of the ideal inter-arch relationship
What does the BO line of the maxilla occlude with in crossbite?
CF line of the mandible
What does the LO line of the mandible occlude with in crossbite?
CF line of the maxilla
What is the net effect of arch length discrepancy?
Tooth to tooth vs. tooth to two teeth relationships
Describe the class I molar relationship of the MB cusp of the maxillary first molar
MB cusp of the max first molar is aligned directly over the buccal groove of the mandibular first molar
Describe the class I molar relationship of the MB cusp of the mandibular first molar
MB cusp of the mand first molar occludes in the embrasure area between the maxillary second premolar and first molar
Describe the class I molar relationship of the ML cusp of the maxillary first molar
ML cusp of the maxillary first molar occludes in the central fossa area of the mandibular first molar
Describe the class II molar relationship of the MB cusp of the maxillary first molar
Situated over the embrasure between the mandibular second premolar and first molar
Describe the class II molar relationship of the MB cusp of the mandibular first molar
Occludes in the central fossa of the maxillary first molar
Describe the class II molar relationship of the DL cusp of the maxillary first molar
Occludes in central fossa of the mandibular first molar
Describe the class III molar relationship of the MB cusp of the maxillary first molar
Is situated over the embrasure between the mandibular first and second molar
Describe the class III molar relationship of the DB cusp of the mandibular first molar
Occludes in the embrasure between distal marginal ridge of the maxillary second premolar and the mesial marginal ridge of the maxillary first molar
Describe the class III molar relationship of the ML cusp of the maxillary first molar
Situated in the mesial pit of the mandibular second molar
What is the vertical overlap in a class I?
Distance the maxillary anterior teeth overlap the mandibular anterior teeth in a vertical direction
2-4mm is “normal”
What is the horizontal overlap in a class I?
Distance the maxillary anterior teeth overlap the mandibular teeth when measured in a horizontal direction
2-4mm is “normal”
What is division 1 in class II anterior teeth?
Great vertical overlap, the mandibular teeth contact the gingival third of the maxillary anterior teeth “deep bite”
What is division 2 in class II anterior teeth?
Maxillary incisors are lingually inclined, laterals overlap the centrals labially
What is the class III anterior tooth relationship?
End to end relationship
Mandibular anterior teeth are so far forward overlapping maxillary anterior teeth
