Unit C module 1 Flashcards Preview

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Flashcards in Unit C module 1 Deck (49)
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1
Q

What is dental age based on?

A

Developmental age scale, based on 3 things:

Amount of crown or root development of permanent teeth

The degree of root resorption of the primary teeth

Which teeth have erupted

2
Q

What does dental age 6 look like?

A

First appearance of permanent teeth. The first permanent tooth to erupt is the mandibular central incisor but it may occassionally be maxillary first permanent molar. Usually mandibular molar will precede the maxillary molar.

These teeth erupt at similar times.

3
Q

What stage of root development is seen prior to eruption of teeth?

A

Between 2/3rds and 3/4ths of their root development which is typical of root development of all permanent teeth at the time they first appear in the mouth.

4
Q

What happens to primary teeth at the time of permanent tooth eruption?

A

Resorption of primary roots begins about the time permanent root development starts so at age 6 the roots of maxillary primary centrals and laterals and mandibular primary lateral incisor roots.

5
Q

Which teeth erupt at dental age 6?

A

Mandibular central incisors

Mandibular first molars

Maxillary first molars

6
Q

Which teeth exhibit root development and resorption of primary teeth at age 6?

A

Maxillary central incisors

Maxillary and mandibular lateral incisors

7
Q

What happens at dental age 7?

A

In the second stage of eruption of permanent teeth:

The maxillary central incisors

Mandibular lateral incisors

At dental age 7 the maxillary lateral incisor has advanced root formation but has not yet erupted

Root development / resorption of primary roots occurs in the maxillary lateral incisors

8
Q

What occurs at dental age 8?

A

The eruption of the maxillary lateral incisors and the beginning of root formation of canines and premolars and the beginning of root resorption of primary canine and molars.

9
Q

What occurs at dental age 9 - 10?

A

After eruption of the maxillary lateral incisors at age 8 no permanent teeth erupt for 2 - 3 years.

Dental ages 9 - 10 are characterized by presence of permanent central and lateral incisors and permanent first and second molars on both arches.

At dental age 9 root development on premolars is occuring 1/3rd of the root of the mandibular canine and the mandibular 1st premolar are completed. Root development just beginning.

The difference in dental age 9 and 10 would be more resorption in the roots of the parimary canines and molars.

10
Q

What occurs at dental age 11?

A

Dental age 11 is characterized by the beginning of eruption of canines and premolars.

At this time, mandibular canine, mandibular first premolar, and maxillary first premolars but sometimes the canine is ahead

11
Q

What must be present at dental age 11?

A

Mandibular: The canine and first premolar

Maxillary arch: The first premolar. Primary canine and second molar are still present.

12
Q

What happens to the permanent canines at dental age 11?

A

Their root development has approached 2/3rds which indicates time for eruption.

13
Q

What happens at dental age 12?

A

The remaining succedaneous permanent teeth erupt into the mouth.

At dental age 12 the 2nd molars of both arches are near eruption.

14
Q

What does succedaneous mean?

A

Permanent teeth which have a primary predecessor (such as canines and premolars)

15
Q

Are permanent molars considered succedaenous?

A

No, they erupt after the 5s

16
Q

What happens at dental age 13 - 15?

A

More root formation in the maxillar and mandibular canines, second premolars, and second permanent molars.

By dental age 15 the roots of all permanent teeth except the third molars should be complete and third molars should be complete and third molars should be apparent on the radiographs even though they will not have erupted.

17
Q

Which tooth erupts first the first premolar or the canine in the maxillary arch?

A

The first premolar

18
Q

Which tooth erupts with the canine in the maxillary arch?

A

The second premolar.

19
Q

How are premolar and canine eruption rates compared in the mandibular arch?

A

Canine is slightly below the first premolar and both erupt at the same time.

20
Q

At what age to the primary mandibular canines start to exfoliate and have their roots resorbed?

A

At dental age 9

21
Q

How does the position of the maxillary canine change with time?

A

It begins development superiorly and moves downward and somewhat forward towards the position where it will emerge eventually.

22
Q

When does root completion usually take place?

A

Usually 2 years after tooth erupts into the mouth

23
Q

How long do teeth continue erupting after initial growth into the mouth?

A

Usually they continue to grow with the growth of the mandible and maxilla apart. They fill the space in.

24
Q

What are the common eruption variations encountered?

A

Eruption of second molars ahead of premolars in the mandibular arch

Eruption of canines ahead of premolars in the maxillary arch. (Maxillary canines and first premolars can also erupt simultaneously like the mandibular case)

Asymmetries in eruption between the right and the left sides

25
Q

What issue is caused by eruption of second molars before premolars?

A

The dental arch could have trouble accomodating the second premolar and may lead to impaction.

This can be solved using orthodontic appliances to hold molars back and to open up space for second premolars.

26
Q

What are the possible consequences of second molars erupting before premolars?

A

There must be enough mandibular growth to allow for third molar development. It can limit available space.

27
Q

What is the common outcome of maxillary canines and first premolars erupting simultaneously?

A

Maxillary canine is likely to be forced labially. This is because the premolars take up the room designed to accomodate the canine so the canine shifts labially.

28
Q

When should asymmetry between left and ride sides be checked?

A

More than 6 months difference can be clinically significant and should be investigated. Impaction of maxillary canines can often be prevented by timely intervention.

29
Q

What is the ugly ducklling stage of tooth development?

A

Incisor positioning early on during development can create a diastema which later corrects itself

30
Q

How does the diastema of early central incisor eruption during the “ugly duckling” stage correct itself?

A

The diastema in the midline tends to close with time as the lateral incisors erupt. This is further repaired by the eruption of the maxillary incisors.

This is because initially the lateral incisors point more distally and then when maxillary canines erupt this pushes them to follow occlusion more correctly.

31
Q

Do diastemas early in development always close up?

A

If the diastema is greater than 2mm

32
Q

Does the ugly duckling stage of development occur in all children?

A

No, it is common enough to be noted as a variation of the usual pattern of eruption.

33
Q

Where do the permanent tooth buds lie relative to the primary dentition?

A

Lingually and apically

34
Q

What is the problem of having lingual eruption of permanent teeth relative to the primary dentition?

A

A tendency for permanent lateral incisors to erupt lingually to their ideal position in the arch. (Permanent teeth erupt more lingually and move more labially)

35
Q

What other things can further accentuate the lingual deviation of mandibular and maxillary permanent incisors?

A

Severe shortage of space can lead to a tendency for the lateral incisors to be displaced lingually.

36
Q

What does absence of normal primary spacing indicate about permanent teeth?

A

There will be crowding.

37
Q

Where are the primate spaces located?

A

Behind the maxillary lateral incisors and the mandibular canines.

38
Q

How much primary space does each arch have?

A

On the average 28.8mm of space is available in the maxillary incisor segment from lateral incisor to lateral incisor. This is 2.6mm more than that needed to accomodate the primary teeth.

In mandibular incisor segment 22.3mm is available on average and is 1.1mm more than required.

When permanent central incisors erupt they are markedly larger than the primary central incisors.

39
Q

What is incisor liability?

A

The lack of adequate space across the incisors because the permanent incisors are likely to become at least slightly malaligned as they erupt.

40
Q

How is the incisor liability overcome?

A

As the permanent teeth erupt they force the canines distally into the primate spaces in the mandibular arch and the lateral incisors in the maxillary arch.

41
Q

Which arch is the spacing more favourable?

A

The maxillary arch

42
Q

What does eruption of first molar and the incisors do to the arch available spaces?

A

They decrease the available space significantly.

43
Q

What are moorees tables?

A

Table of available spaces as observed by Moorrees and other workers at Harvard.

They referred to the incisor crowding in the mandible as incisor liability.

44
Q

How is mandibular incisor liability overcome?

A

3 different sources:

Distal movement into the primate spaces.

Labial eruption

Increase in the width of the dental arch (transverse growth)

45
Q

At which dental age is eruption of teeth completed?

A

All teeth continue to erupt until age 15 even after they reach the occlusal plane to be consistent with facial growth.

46
Q

At dental age 7, where is the maxillary canine located?

A

The maxillary canines initially are very high above and only slightly distal to the lateral incisors. Their location almost in the floor of the orbit is why they’re sometimes called “eye teeth”.

47
Q

(A) Eruption of the maxillary canine coincident with the maxillary first premolar rarely is a problem because (B) the erupting canine tends to close spaces between the incisors and creates space in that way.

For A and B are they True or false?

A

The first statement is false and the second one true. Early eruption of the canine is likely to create a problem, even though its eruption tends to close spaces between the incisors and some space is gained in that way. Whether or not there’s incisor spacing, if the canine erupts along with the first premolar, before the second primary molar is lost and some additional space becomes available in that area, it’s likely to be displaced facially, and orthodontic treatment will be needed to get it back.

48
Q

How much additional space for the incisors is gained by the normal mechanisms to overcome incisor liability?

A

The normal mechanisms contribute about 3 mm, or half the width of a lower incisor. If more space than that would be needed to obtain incisor alignment, it probably won’t be forthcoming from normal development alone.

49
Q

Dental age 11 is characteried by eruption of:

A

Mandibular canine and all first premolars

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