Development of the Primary Dentition

Question 1

Sequence of Calcification of Primary Teeth

Answer 1

A,D,B,C,E / 14-18 weeks in utero

How much calcified @ birth?
a - 60/80%
d - 60%
b - 33%
c - cusps united, occlusal calcified
e - cusps, united, occlusal not calcified

Question 2

Sequence of Eruption of Primary teeth

Answer 2

A,B,D,C,E
girls faster than boys
6 mo variation = normal
no significant left/ right dif.

Question 3

Sequence and Timing of Eruption of Primary Teeth

Answer 3

Max, Mand

a - 10 mo, 8 mo
b - 11 mo, 13 mo
c - 19 mo, 20 mo
d - 16 mo, 16 mo
e - 29 mo, 27 mo

Question 4

Positioning of Primary Teeth

Answer 4

Primary anterior teeth are labial to developing permanent teeth

Permanent ant teeth erupt in a lingual to labial direction

Question 5

Occlusion of the Primary Second Molar

Answer 5

Look at distal aspect of the 2nd molar

Flush terminal plane
Mesial step
Disto step
Mesio step

*distal aspect of send primary molar

**Maxillary teeth fit 1/2 step distal to the mandibular teeth in the buccal segment

Question 6

Flush Terminal Plane

Answer 6

Class I type of occlusion

yield end to end permanent molars

Question 7

Late mesial shift

Answer 7

FTP primary molar, molar moves into leeway space, Class I

MB cusp into buccal groove of mand 1st molar

Question 8

Mesial Step

Answer 8

Mand move more mesial than distal - Class I

Question 9

Disto Step

Answer 9

Permanent molar into Class II occlusion

Question 10

Mesio Step

Answer 10

“exaggerated mesial step”
pseudo-class III
Class III resultant
MB cusp of primary max molar on the DB cusp of 1st man molar

Question 11

Primary cuspid occlusion

Answer 11

**Look at long axis of the max cuspid

Neutro cuspid (Class I) "zipper"
Disto cuspid (Class II)
Mesio cuspid (Class III)

Question 12

The ideal primary occlusion

Answer 12

ovoid arches, good interdental or primary spacing, flush terminal plane or mesial strep molars, neutro cuspids

Question 13

Arch Length Prediction from Alignment of Primary Teeth

Answer 13

Prim Alignment/ Perm Outcome

\+Crowding/ Probable ext
\+No spacing/ possible ext
\+Fair spacing/ mild-mod crowd
\+Good spacing/ no-mild crowd
\+Excess spacing/ no crowding/excess

Question 14

What is normal for ant radiographs in primary dentition

Answer 14

Maxillary Anterior
Should be able to outline 4 max incisors
Central and laterals will overlap
At <4, perm centrals are positioned more nasally than lateral incisors
At about 4.5, perm centrals are even w/ max lateral incisors then surpass laterals and erupt b4 laterals
On average, perm tooth has 3/4 root development when it pierces the gingival margin

Question 15

Supernumerary Teeth

Answer 15

found most frequently in max incisor region (mesiodens) and occasionally in premolar area

2-3% supernumerary teeth, m more common

Management: Don’t extract too early or late
if facing down, track,

Question 16

Symmetry

Answer 16

Reasonable symmetrical in eruption of teeth (mirror).
Determine why asymmetry exists

Possible supernumerary blocking

Question 17

Number issues

Answer 17

missing lateral incisors: missing lateral incisor

Question 18

Ankylosis of Primary Molars

Answer 18

anatomical fusion of alveolar bone w/ cementum
can occur any time during eruption, either before or after the tooth erupts into the oral cavity

Epidemiology:
common: 1% blacks, 4% whites
familial pattern
higher prevalence w/ absent premolars

Diagnosis:
Appearance - out of occlusion
No mobility - even w/ advanced resorption
Hollow sound when tapped
perhaps seen on radiograph

Suspicious of congenitally missing permanent teeth

Question 19

How does Ankylosis occur

Answer 19

most severe cases are youngest
In early development, bicuspid is formed lateral to the bicuspid
Primary tooth is ankylosed and permanent successor does not migrate to normal position