Development of Occlusion

Question 1

more prominent groove on the gum pads dividing the primary canine and primary first molar

Answer 1

lateral sulcus

Question 2

Primary dentition begins with ? and ends with?

Answer 2

begins with the eruption of the first primary tooth, ends with the eruption of the first permanent tooth

Question 3

relationship of the distal surface of primary second molars

Answer 3

terminal plane

Question 4

Where is the primate space?

Answer 4

Maxilla- btw primary lateral incisor and primary canine
Mandible- btw primary canine and primary 1st molar

Question 5

difference in combined mesiodistal width of primary canine, primary 1st molar, and primary 2nd molar and their subsequent underlying teeth (canine, first and second PM)

Answer 5

leeway space

Question 6

space between primary incisors, necessary to prevent crowding of permanent teeth due to increased size

Answer 6

interdental space

Question 7

difference in size between primary and permanent incisors

Answer 7

incisor liability

Question 8

Mixed dentition begins with ? and ends with?

Answer 8

begins with eruption of the first primary tooth, ends with exfoliation of the last primary tooth

Question 9

Incisors tend to erupt _________. Why? Exception?

Answer 9

Incisors tend to erupt lingually due to permanent tooth buds developing lingual and apical to primary teeth. Maxillary central incisors are the exception, because they are pushed labially by the tongue as they erupt and can erupt laterally.

Question 10

How does the terminal plane relationship of primary second molars guide the position of the first permanent molars?

Answer 10

Mesial step- 90% class I, 10% class III
Distal step- nearly 100% class II
Flush terminal plane- end to end molar relationship most often (will eventually become class I or II, but all are possible)

Question 11

early vs late mesial shift

Answer 11

Early- permanent first molars erupt (~6 years) and close the primate space by shifting mesially

Late- eruption of permanent second molars close leeway space ~12 years and pushes first permanent molars mesially

Question 12

Is there usually more mesial shift in the maxilla or mandible?

Answer 12

mandible

Question 13

normal width of the original diastema in primary teeth

Answer 13

<2mm

Question 14

normal overbite, overjet, and molar relationship in permanent dentition

Answer 14

10-20% overbite
1-3mm overjet
Class I occlusion

Question 15

curvature of arch in the sagittal plane

Answer 15

Curve of Spee

Question 16

curvature of arch in the frontal plane

Answer 16

Curve of Wilson

Question 17

What happens to arch LENGTH during the transition from mixed to permanent dentition? Perimeter? Intercanine width? Intermolar width?

Answer 17

Arch length decreases
Arch perimeter slightly increases in upper arch and significantly decreases in lower arch
Intercanine width increases
Intermolar width increases