9th Class Flashcards
Andrews’ Six Keys to normal (optimal) occlusion are a widely quoted set of static
occlusal goals for teeth relationships in the inter-cuspal position:
- Correct inter-arch relationships (Classification).
- Correct crown angulation (Tip).
- Correct crown inclination (Torque).
- No rotations.
- Tight contact points.
- Flat curve of Spee (0.0 - 2.5 mm).
The mesio-buccal cusp of the upper first permanent molar falls where?
within the groove between the mesial and middle cusps of the lower
first permanent molar.
The distal surface of the distal marginal ridge of the upper first
permanent molar contacts and occludes where?
with the mesial surface of
the mesial marginal ridge of the lower second molar.
The mesio-lingual cusp of the upper first molar seats where?
in the central
fossa of the lower first molar.
The premolars enjoy a ________ relationship buccally,
and a ________ relationship lingually.
cusp-embrasure; cusp fossa
Maxillary Canine has a ______ relationship with
Mandibular Canine & 1st Premolar.
cusp-embrasure
T/F: Crown angulation refers to angulation (Tip) of the long axis of the
crown, not to angulation of the long axis of the entire tooth.
True
• Facial axis of the clinical crown (FACC) best viewed from the labial or buccal perspective.
• For all teeth except molars, is located at the mid-developmental ridge that runs
vertically and is the most prominent portion in the central area of the labial or buccal
surface.
• The facial axis of molar crowns is identified by the dominant vertical groove on the
buccal surface.
Crown Angulation (Tip)
Crown Angulation (Tip) A “\_\_ reading" when the gingival portion of the FACC is distal to the incisal portion.
+ reading
Crown Angulation (Tip) A “ \_\_ reading" when the gingival portion of the FACC is mesial to the incisal portion.
- reading
Each normal model had a _____ inclination of the gingival portion of each
crown, It varied with each tooth type, but within each type the tip pattern was
consistent from individual to individual.
distal inclincation
______ is formed by a line which bears 90° to the occlusal plane and FACC. (as viewed from the mesial or distal).
Crown inclination angle
(crown inclination)
A ___ reading is given if the gingival portion of the tangent line of the crown is lingual to the incisal portion.
+ reading
(crown inclination)
A __ reading is recorded when the gingival portion of the tangent line of the crown is labial to the incisal portion.
- reading
ANTERIOR CROWN INCLINATION:
• In upper incisors __ crown inclination.
+ inclination
ANTERIOR CROWN INCLINATION:
• In lower incisors __ crown inclination.
- inclination
Properly inclined ______ crowns contribute to normal overbite and posterior occlusion.
anterior
A ____ crown inclination for each crown from the U canine through the U-
2nd PM.
minus inclincation for upper canine thru upper 2nd PMs
Are the upper molars or pms more negative in terms of crown inclincation?
Molars
A progressively greater _____ crown inclination existed from the lower
canines through the lower 2nd molars.
“minus”
As you move from the lower canine posteriorly in the mandible, how do the crown inclinations change?
Progressive get more (-)
T/F: Teeth should be free of undesirable rotations.
True
Rotated molar, would occupy
____ space than normal, creating a situation unreceptive to normal
occlusion.
More space
T/F: Contact points should be tight (no spaces).
True
There is a natural tendency for the curve of Spee to ____ with time.
deepen
A ____ plane of curve of spee should be a treatment goal.
flat
Lower jaw’s growth downward and forward sometimes is ______ and continues longer than that of the upper jaw.
faster
Lower jaw’s growth downward and forward sometimes is faster and continues longer than that of the upper jaw.
his causes the Lower Anterior teeth to be: (what 4 things happen)
- Forced back and up.
- Crowded lower anterior.
- A deeper overbite.
- Deeper curve of Spee.
The lower teeth need to be ______ mesio-distally compared to the
upper teeth.
smaller
T/F: When the lower teeth are not smaller, it becomes impossible for all
the lower teeth to fit inside the upper arch.
True
•This analysis helps in determining the differences in size between the maxillary and mandibular teeth and ideal relationship within the inter-arch.
•The Analysis or Ratio is a useful measurement tool that determines the relative M-D tooth size of upper and lower teeth.
•This Analysis has been identified for both the entire arch and for the anterior teeth.
➢These ratios were developed because there is generally more variability in the anterior tooth size than posterior tooth size.
Bolton analysis
