Occlusion Flashcards
Define Occlusion
relationship of mandibular teeth when they come in contact with the
maxillary teeth
Ideal occlusion
harmonious static and dynamic relationship of teeth and jaw,
all teeth in the maxillary arch are in contact with all teeth of the mandibular arch.
- Maxillary teeth slightly overlap the mandibular teeth on the facial surface
- Lingual cusps of the maxillary teeth rest in the fossae of the mandibular teeth, and the buccal cusps of the mandibular teeth rest in the fossae of the maxillary teeth
Define Malocclusion
deviation from the ideal, abnormal occlusion
Define Skeletal Classification
relationship of the bone of the maxilla to the bone of the
mandible
Types of occlusion classifications
A. Class I - “normal” or “ideal” relationship of the maxilla to the mandible, mesognathic or orthognathic profile
B. Class II - mandible is retruded, pushed back, mandible has a distal relationship to the maxilla, retrognathic profile
C. Class III - mandible is protruded, pushed forward, mandible has a mesial relationship to the maxilla, prognathic profile
Define Dental Classification
relationship of the teeth of the mandibular to the teeth of the
maxilla, particularly 1st molars, and canines
Bilateral / Unilateral
on both sides / on one side of the mouth
Occlusion classifications can be bilateral or unilateral
E. H. Angle’s Classification Class 1
- Class I - neutrocclusion, ideal relationship
- Molar relationship: mesiobuccal cusp of permanent maxillary 1st molar is directly in line with the mesiobuccal groove of the mandibular 1st molar
- Canine relationship: permanent maxillary canine fits into the facial embrasure between the mandibular canine and 1st premolar
E. H. Angle’s Classification Class 2
- Class II - distocclusion
- Molar Relationship: Mesiobuccal Cusp of Permanent Maxillary 1st molar is anterior to the mesiobuccal groove of the mandibular 1stmolar by at least the width of a premolar.
- Canine relationship - permanent maxillary canine is anterior to
facial embrasure of mandibular canine and 1st premolar by at least the width of a premolar - Less than the width of a premolar is a tendency to Class II
Division I
Maxillary central incisors are slightly protruded
Division II
maxillary central incisors are retruded, inclined lingually, laterals
often slightly overlap central incisors have the appearance of
being overlapped on the central incisors
Clinical findings that may be present in Class II
- Overjet
- Severe/deep overbite
- Crowded maxillary anterior teeth
E. H. Angle’s Classification Class 3
- mesiocclusion
- Molar relationship - mesiobuccal cusp of the permanent maxillary 1st molar is distal to the mesiobuccal groove of the mandibular 1st molar by at least the width of a premolar
- Canine relationship - permanent maxillary canine is distal to the facial embrasure of the mandibular canine and 1st premolar by at least the width of a premolar
- Less than the width of a premolar is a tendency to Class III
Clinical findings that may be present with Class III occlusion
- Anterior crossbite
- Edge to edge
- Mandibular incisors crowding
- Mandibular incisors that are lingually tipped
Factors influencing occlusion
A. Arrangement of teeth in the arch
B. Relation of the mandibular arch to the maxillary arch
C. Relation of the mandible to the maxilla
D. Temporomandibular Joint (TMJ) and its parts
E. Muscles, nerves, ligaments, and soft tissues that affect the position of the mandible
Abnormalities that may be detrimental to dental health
- Maligned teeth
- Biting and bruxing habits
- Tongue thrusts
- Deflective tooth contacts
- Balancing side interferences
- Improperly designed restorations
Malocclusion
occurs when groups of teeth within the arch are not aligned to fit
into ideal arch form, do not form a level plane, or when individual teeth are not aligned to fit ideal arch form
Labioversion, labial version
tooth is out of alignment to the labial or
buccal compared to the arch, or other teeth
Buccoversion, buccal version
refers to posterior tooth
LInguoversion, lingual version
tooth is out of alignment to the lingual
compared to the arch or other teeth
Torsoversion
teeth are rotated
Supraeruption, extrusion
tooth that is over erupted, abnormally long
relative to the rest of the occlusal surfaces
Infraocclusion, infraversion
tooth is abnormally short relative to the
rest of the occlusal plane
Crossbite
Mandibular teeth not within the confines of the maxillary
teeth
- Anterior - maxillary incisors or canines re lingual to mandibular incisors or canine
- Posterior - maxillary posterior teeth are more lingual to mandibular
teeth, maxillary lingual cusps are not in the fossae of the mandibular
teeth
Edge to edge
incisal edge of maxillary anterior teeth occlude with the
incisal edge of the mandibular teeth
End to end
posterior teeth occlude cusp to cusp
Open bit
mandibular teeth do not touch maxillary teeth, no vertical
overlap
- can be caused by thumb sucking
- can be caused by tongue thrusting
Overjet - horizontal
overlap, amount of facial horizontal overlap
between the maxillary anterior teeth to the mandibular teeth
Normal overjet is 2-3 mm, measured with a probe
Overbite - vertical
overlap, extension of the incisal edges of the maxillary
anterior teeth below the incisal edges of the
mandibular anterior teeth in a vertical direction
Normal/slight overbite
Overlap occurs within the incisal 1/3 of
mandibular anterior teeth
Moderate overbite
overlap occurs in the middle 1/3 of mandibular
anterior teeth
Severe overbite/deep overbite
Overlap into the cervical 1/3 of
mandibular anterior teeth
- Could see bite marks in the palate with severe
Vertical dimension
a vertical measurement between anatomic or arbitrary
points on the upper or lower face
Resting Vertical dimension
at rest, with lips together, teeth should be 1-
2mm apart
Centric occlusion
relation of maxillary and mandibular occlusal surfaces
when teeth in maximum contact, or intercuspation (fitting together of the surfaces of the opposing teeth
Centric relation
relation of upper and lower jaw, when the head of the condyle
is in the most posterior-superior position in the glenoid (mandibular) fossa, jaw is back as far as it can go this can be seen when swallowing
Functional (dynamic) occlusion
refers to the tooth contacts, while the
mandible is in action
Intercuspation
buccal cusps of the mandibular teeth are interlocked between
buccal and lingual cusps of maxillary teeth
Mesial drift
Erupted teeth drift toward the midline
Vertical alignment of teeth
Teeth are not vertically straight up and down
- Mandibular teeth tip lingually
- Maxillary teeth tip buccally
- Anterior teeth tip slightly forward
Lateral excursion
mandible moves to the right and left
Working side
side toward which the mandible moves, maxillary and
mandibular cusps touch
Balancing side
non-functional side, teeth do not contact
Canine guidance or rise
mandible canine opens the bite by gliding
down the lingual surface of the maxillary canine
Group function
premolars occlude during lateral excursion, premolars
should only assist, canines take the brunt of the occlusion
Protrusion
mandible moves forward
Only the 4 anterior touch, but may include the canines. Posteriors have no contact
Open contacts
sites where interproximal space exists because proximal crests
do not meet
Reasons for open contacts
- Developmental disturbances
- Missing teeth
- Oral habits
- Dental disease
- Overdeveloped frena
- Faulty dentistry
Diastema
space between two adjacent teeth in the same arch that is not the
result of missing teeth, most commonly seen between central incisors
Curve of Wilson
transverse occlusal curve, side to side, mandibular teeth
concave, since mandibular teeth tilt lingually
Curve of Spee
from the lateral view, usually from the buccal aspects when
teeth are in centric occlusion cusp tips of posterior teeth conform to a fairly even curve in and anterior to posterior direction, mandibular teeth curve is concave, maxillary curve is convex
Occlusal Trauma
periodontal injury is caused by repeated occlusal forces which
are excessive
Types of Occlusal Trauma
- Primary occlusal trauma - excessive force with normal bone support
- Secondary occlusal trauma - excessive force with bone loss and
inadequate bone support
*NOTE - occlusal trauma causes periodontal disease only in the presence of bacteria
Causes of occlusal trauma
- Premature contact
- Only a few teeth in contact - which produces unequal pressure
- Initial contacts on inclined planes of cusps, which produce unequal
pressure - Heavy forces in lateral or horizontal direction
- Increased frequency, intensity or duration of contacts such as bruxism, clenching
Clinical Findings of Occlusal Trauma
- Tooth mobility
- Fremitus - vibration
- Tooth sensitivity
- Wear facets
- Open contacts
- TMJ disorders
Radiographic findings of occlusal trauma
- Widened periodontal ligament (PDL)
- Thickened lamina dura - thin covering of alveolar bone seen
radiographically - Angular/vertical bone loss
- Root resorption
- Furcation involvement
